glib inlined into SameTime

git-svn-id: http://svn.miranda-ng.org/main/trunk@8685 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

1 files changed, 4663 insertions, 0 deletions

diff --git a/protocols/Sametime/src/glib/gvariant.c b/protocols/Sametime/src/glib/gvariant.c
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+++ b/protocols/Sametime/src/glib/gvariant.c
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+/*
+ * Copyright © 2007, 2008 Ryan Lortie
+ * Copyright © 2010 Codethink Limited
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Ryan Lortie <desrt@desrt.ca>
+ */
+
+/* Prologue {{{1 */
+
+#include "config.h"
+
+#include <glib/gvariant-serialiser.h>
+#include "gvariant-internal.h"
+#include <glib/gvariant-core.h>
+#include <glib/gtestutils.h>
+#include <glib/gstrfuncs.h>
+#include <glib/ghash.h>
+#include <glib/gmem.h>
+
+#include <string.h>
+
+
+/**
+ * SECTION: gvariant
+ * @title: GVariant
+ * @short_description: strongly typed value datatype
+ * @see_also: GVariantType
+ *
+ * #GVariant is a variant datatype; it stores a value along with
+ * information about the type of that value.  The range of possible
+ * values is determined by the type.  The type system used by #GVariant
+ * is #GVariantType.
+ *
+ * #GVariant instances always have a type and a value (which are given
+ * at construction time).  The type and value of a #GVariant instance
+ * can never change other than by the #GVariant itself being
+ * destroyed.  A #GVariant can not contain a pointer.
+ *
+ * #GVariant is reference counted using g_variant_ref() and
+ * g_variant_unref().  #GVariant also has floating reference counts --
+ * see g_variant_ref_sink().
+ *
+ * #GVariant is completely threadsafe.  A #GVariant instance can be
+ * concurrently accessed in any way from any number of threads without
+ * problems.
+ *
+ * #GVariant is heavily optimised for dealing with data in serialised
+ * form.  It works particularly well with data located in memory-mapped
+ * files.  It can perform nearly all deserialisation operations in a
+ * small constant time, usually touching only a single memory page.
+ * Serialised #GVariant data can also be sent over the network.
+ *
+ * #GVariant is largely compatible with DBus.  Almost all types of
+ * #GVariant instances can be sent over DBus.  See #GVariantType for
+ * exceptions.
+ *
+ * For convenience to C programmers, #GVariant features powerful
+ * varargs-based value construction and destruction.  This feature is
+ * designed to be embedded in other libraries.
+ *
+ * There is a Python-inspired text language for describing #GVariant
+ * values.  #GVariant includes a printer for this language and a parser
+ * with type inferencing.
+ *
+ * <refsect2>
+ *  <title>Memory Use</title>
+ *  <para>
+ *   #GVariant tries to be quite efficient with respect to memory use.
+ *   This section gives a rough idea of how much memory is used by the
+ *   current implementation.  The information here is subject to change
+ *   in the future.
+ *  </para>
+ *  <para>
+ *   The memory allocated by #GVariant can be grouped into 4 broad
+ *   purposes: memory for serialised data, memory for the type
+ *   information cache, buffer management memory and memory for the
+ *   #GVariant structure itself.
+ *  </para>
+ *  <refsect3>
+ *   <title>Serialised Data Memory</title>
+ *   <para>
+ *    This is the memory that is used for storing GVariant data in
+ *    serialised form.  This is what would be sent over the network or
+ *    what would end up on disk.
+ *   </para>
+ *   <para>
+ *    The amount of memory required to store a boolean is 1 byte.  16,
+ *    32 and 64 bit integers and double precision floating point numbers
+ *    use their "natural" size.  Strings (including object path and
+ *    signature strings) are stored with a nul terminator, and as such
+ *    use the length of the string plus 1 byte.
+ *   </para>
+ *   <para>
+ *    Maybe types use no space at all to represent the null value and
+ *    use the same amount of space (sometimes plus one byte) as the
+ *    equivalent non-maybe-typed value to represent the non-null case.
+ *   </para>
+ *   <para>
+ *    Arrays use the amount of space required to store each of their
+ *    members, concatenated.  Additionally, if the items stored in an
+ *    array are not of a fixed-size (ie: strings, other arrays, etc)
+ *    then an additional framing offset is stored for each item.  The
+ *    size of this offset is either 1, 2 or 4 bytes depending on the
+ *    overall size of the container.  Additionally, extra padding bytes
+ *    are added as required for alignment of child values.
+ *   </para>
+ *   <para>
+ *    Tuples (including dictionary entries) use the amount of space
+ *    required to store each of their members, concatenated, plus one
+ *    framing offset (as per arrays) for each non-fixed-sized item in
+ *    the tuple, except for the last one.  Additionally, extra padding
+ *    bytes are added as required for alignment of child values.
+ *   </para>
+ *   <para>
+ *    Variants use the same amount of space as the item inside of the
+ *    variant, plus 1 byte, plus the length of the type string for the
+ *    item inside the variant.
+ *   </para>
+ *   <para>
+ *    As an example, consider a dictionary mapping strings to variants.
+ *    In the case that the dictionary is empty, 0 bytes are required for
+ *    the serialisation.
+ *   </para>
+ *   <para>
+ *    If we add an item "width" that maps to the int32 value of 500 then
+ *    we will use 4 byte to store the int32 (so 6 for the variant
+ *    containing it) and 6 bytes for the string.  The variant must be
+ *    aligned to 8 after the 6 bytes of the string, so that's 2 extra
+ *    bytes.  6 (string) + 2 (padding) + 6 (variant) is 14 bytes used
+ *    for the dictionary entry.  An additional 1 byte is added to the
+ *    array as a framing offset making a total of 15 bytes.
+ *   </para>
+ *   <para>
+ *    If we add another entry, "title" that maps to a nullable string
+ *    that happens to have a value of null, then we use 0 bytes for the
+ *    null value (and 3 bytes for the variant to contain it along with
+ *    its type string) plus 6 bytes for the string.  Again, we need 2
+ *    padding bytes.  That makes a total of 6 + 2 + 3 = 11 bytes.
+ *   </para>
+ *   <para>
+ *    We now require extra padding between the two items in the array.
+ *    After the 14 bytes of the first item, that's 2 bytes required.  We
+ *    now require 2 framing offsets for an extra two bytes.  14 + 2 + 11
+ *    + 2 = 29 bytes to encode the entire two-item dictionary.
+ *   </para>
+ *  </refsect3>
+ *  <refsect3>
+ *   <title>Type Information Cache</title>
+ *   <para>
+ *    For each GVariant type that currently exists in the program a type
+ *    information structure is kept in the type information cache.  The
+ *    type information structure is required for rapid deserialisation.
+ *   </para>
+ *   <para>
+ *    Continuing with the above example, if a #GVariant exists with the
+ *    type "a{sv}" then a type information struct will exist for
+ *    "a{sv}", "{sv}", "s", and "v".  Multiple uses of the same type
+ *    will share the same type information.  Additionally, all
+ *    single-digit types are stored in read-only static memory and do
+ *    not contribute to the writable memory footprint of a program using
+ *    #GVariant.
+ *   </para>
+ *   <para>
+ *    Aside from the type information structures stored in read-only
+ *    memory, there are two forms of type information.  One is used for
+ *    container types where there is a single element type: arrays and
+ *    maybe types.  The other is used for container types where there
+ *    are multiple element types: tuples and dictionary entries.
+ *   </para>
+ *   <para>
+ *    Array type info structures are 6 * sizeof (void *), plus the
+ *    memory required to store the type string itself.  This means that
+ *    on 32bit systems, the cache entry for "a{sv}" would require 30
+ *    bytes of memory (plus malloc overhead).
+ *   </para>
+ *   <para>
+ *    Tuple type info structures are 6 * sizeof (void *), plus 4 *
+ *    sizeof (void *) for each item in the tuple, plus the memory
+ *    required to store the type string itself.  A 2-item tuple, for
+ *    example, would have a type information structure that consumed
+ *    writable memory in the size of 14 * sizeof (void *) (plus type
+ *    string)  This means that on 32bit systems, the cache entry for
+ *    "{sv}" would require 61 bytes of memory (plus malloc overhead).
+ *   </para>
+ *   <para>
+ *    This means that in total, for our "a{sv}" example, 91 bytes of
+ *    type information would be allocated.
+ *   </para>
+ *   <para>
+ *    The type information cache, additionally, uses a #GHashTable to
+ *    store and lookup the cached items and stores a pointer to this
+ *    hash table in static storage.  The hash table is freed when there
+ *    are zero items in the type cache.
+ *   </para>
+ *   <para>
+ *    Although these sizes may seem large it is important to remember
+ *    that a program will probably only have a very small number of
+ *    different types of values in it and that only one type information
+ *    structure is required for many different values of the same type.
+ *   </para>
+ *  </refsect3>
+ *  <refsect3>
+ *   <title>Buffer Management Memory</title>
+ *   <para>
+ *    #GVariant uses an internal buffer management structure to deal
+ *    with the various different possible sources of serialised data
+ *    that it uses.  The buffer is responsible for ensuring that the
+ *    correct call is made when the data is no longer in use by
+ *    #GVariant.  This may involve a g_free() or a g_slice_free() or
+ *    even g_mapped_file_unref().
+ *   </para>
+ *   <para>
+ *    One buffer management structure is used for each chunk of
+ *    serialised data.  The size of the buffer management structure is 4
+ *    * (void *).  On 32bit systems, that's 16 bytes.
+ *   </para>
+ *  </refsect3>
+ *  <refsect3>
+ *   <title>GVariant structure</title>
+ *   <para>
+ *    The size of a #GVariant structure is 6 * (void *).  On 32 bit
+ *    systems, that's 24 bytes.
+ *   </para>
+ *   <para>
+ *    #GVariant structures only exist if they are explicitly created
+ *    with API calls.  For example, if a #GVariant is constructed out of
+ *    serialised data for the example given above (with the dictionary)
+ *    then although there are 9 individual values that comprise the
+ *    entire dictionary (two keys, two values, two variants containing
+ *    the values, two dictionary entries, plus the dictionary itself),
+ *    only 1 #GVariant instance exists -- the one refering to the
+ *    dictionary.
+ *   </para>
+ *   <para>
+ *    If calls are made to start accessing the other values then
+ *    #GVariant instances will exist for those values only for as long
+ *    as they are in use (ie: until you call g_variant_unref()).  The
+ *    type information is shared.  The serialised data and the buffer
+ *    management structure for that serialised data is shared by the
+ *    child.
+ *   </para>
+ *  </refsect3>
+ *  <refsect3>
+ *   <title>Summary</title>
+ *   <para>
+ *    To put the entire example together, for our dictionary mapping
+ *    strings to variants (with two entries, as given above), we are
+ *    using 91 bytes of memory for type information, 29 byes of memory
+ *    for the serialised data, 16 bytes for buffer management and 24
+ *    bytes for the #GVariant instance, or a total of 160 bytes, plus
+ *    malloc overhead.  If we were to use g_variant_get_child_value() to
+ *    access the two dictionary entries, we would use an additional 48
+ *    bytes.  If we were to have other dictionaries of the same type, we
+ *    would use more memory for the serialised data and buffer
+ *    management for those dictionaries, but the type information would
+ *    be shared.
+ *   </para>
+ *  </refsect3>
+ * </refsect2>
+ */
+
+/* definition of GVariant structure is in gvariant-core.c */
+
+/* this is a g_return_val_if_fail() for making
+ * sure a (GVariant *) has the required type.
+ */
+#define TYPE_CHECK(value, TYPE, val) \
+  if G_UNLIKELY (!g_variant_is_of_type (value, TYPE)) {           \
+    g_return_if_fail_warning (G_LOG_DOMAIN, G_STRFUNC,            \
+                              "g_variant_is_of_type (" #value     \
+                              ", " #TYPE ")");                    \
+    return val;                                                   \
+  }
+
+/* Numeric Type Constructor/Getters {{{1 */
+/* < private >
+ * g_variant_new_from_trusted:
+ * @type: the #GVariantType
+ * @data: the data to use
+ * @size: the size of @data
+ * @returns: a new floating #GVariant
+ *
+ * Constructs a new trusted #GVariant instance from the provided data.
+ * This is used to implement g_variant_new_* for all the basic types.
+ */
+static GVariant *
+g_variant_new_from_trusted (const GVariantType *type,
+                            gconstpointer       data,
+                            gsize               size)
+{
+  GVariant *value;
+  GBuffer *buffer;
+
+  buffer = g_buffer_new_from_data (data, size);
+  value = g_variant_new_from_buffer (type, buffer, TRUE);
+  g_buffer_unref (buffer);
+
+  return value;
+}
+
+/**
+ * g_variant_new_boolean:
+ * @boolean: a #gboolean value
+ * @returns: a floating reference to a new boolean #GVariant instance
+ *
+ * Creates a new boolean #GVariant instance -- either %TRUE or %FALSE.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_boolean (gboolean value)
+{
+  guchar v = value;
+
+  return g_variant_new_from_trusted (G_VARIANT_TYPE_BOOLEAN, &v, 1);
+}
+
+/**
+ * g_variant_get_boolean:
+ * @value: a boolean #GVariant instance
+ * @returns: %TRUE or %FALSE
+ *
+ * Returns the boolean value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_BOOLEAN.
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_get_boolean (GVariant *value)
+{
+  const guchar *data;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_BOOLEAN, FALSE);
+
+  data = g_variant_get_data (value);
+
+  return data != NULL ? *data != 0 : FALSE;
+}
+
+/* the constructors and accessors for byte, int{16,32,64}, handles and
+ * doubles all look pretty much exactly the same, so we reduce
+ * copy/pasting here.
+ */
+#define NUMERIC_TYPE(TYPE, type, ctype) \
+  GVariant *g_variant_new_##type (ctype value) {                \
+    return g_variant_new_from_trusted (G_VARIANT_TYPE_##TYPE,   \
+                                       &value, sizeof value);   \
+  }                                                             \
+  ctype g_variant_get_##type (GVariant *value) {                \
+    const ctype *data;                                          \
+    TYPE_CHECK (value, G_VARIANT_TYPE_ ## TYPE, 0);             \
+    data = g_variant_get_data (value);                          \
+    return data != NULL ? *data : 0;                            \
+  }
+
+
+/**
+ * g_variant_new_byte:
+ * @byte: a #guint8 value
+ * @returns: a floating reference to a new byte #GVariant instance
+ *
+ * Creates a new byte #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_byte:
+ * @value: a byte #GVariant instance
+ * @returns: a #guchar
+ *
+ * Returns the byte value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_BYTE.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (BYTE, byte, guchar)
+
+/**
+ * g_variant_new_int16:
+ * @int16: a #gint16 value
+ * @returns: a floating reference to a new int16 #GVariant instance
+ *
+ * Creates a new int16 #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_int16:
+ * @value: a int16 #GVariant instance
+ * @returns: a #gint16
+ *
+ * Returns the 16-bit signed integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_INT16.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (INT16, int16, gint16)
+
+/**
+ * g_variant_new_uint16:
+ * @uint16: a #guint16 value
+ * @returns: a floating reference to a new uint16 #GVariant instance
+ *
+ * Creates a new uint16 #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_uint16:
+ * @value: a uint16 #GVariant instance
+ * @returns: a #guint16
+ *
+ * Returns the 16-bit unsigned integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_UINT16.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (UINT16, uint16, guint16)
+
+/**
+ * g_variant_new_int32:
+ * @int32: a #gint32 value
+ * @returns: a floating reference to a new int32 #GVariant instance
+ *
+ * Creates a new int32 #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_int32:
+ * @value: a int32 #GVariant instance
+ * @returns: a #gint32
+ *
+ * Returns the 32-bit signed integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_INT32.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (INT32, int32, gint32)
+
+/**
+ * g_variant_new_uint32:
+ * @uint32: a #guint32 value
+ * @returns: a floating reference to a new uint32 #GVariant instance
+ *
+ * Creates a new uint32 #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_uint32:
+ * @value: a uint32 #GVariant instance
+ * @returns: a #guint32
+ *
+ * Returns the 32-bit unsigned integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_UINT32.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (UINT32, uint32, guint32)
+
+/**
+ * g_variant_new_int64:
+ * @int64: a #gint64 value
+ * @returns: a floating reference to a new int64 #GVariant instance
+ *
+ * Creates a new int64 #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_int64:
+ * @value: a int64 #GVariant instance
+ * @returns: a #gint64
+ *
+ * Returns the 64-bit signed integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_INT64.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (INT64, int64, gint64)
+
+/**
+ * g_variant_new_uint64:
+ * @uint64: a #guint64 value
+ * @returns: a floating reference to a new uint64 #GVariant instance
+ *
+ * Creates a new uint64 #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_uint64:
+ * @value: a uint64 #GVariant instance
+ * @returns: a #guint64
+ *
+ * Returns the 64-bit unsigned integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_UINT64.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (UINT64, uint64, guint64)
+
+/**
+ * g_variant_new_handle:
+ * @handle: a #gint32 value
+ * @returns: a floating reference to a new handle #GVariant instance
+ *
+ * Creates a new handle #GVariant instance.
+ *
+ * By convention, handles are indexes into an array of file descriptors
+ * that are sent alongside a DBus message.  If you're not interacting
+ * with DBus, you probably don't need them.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_handle:
+ * @value: a handle #GVariant instance
+ * @returns: a #gint32
+ *
+ * Returns the 32-bit signed integer value of @value.
+ *
+ * It is an error to call this function with a @value of any type other
+ * than %G_VARIANT_TYPE_HANDLE.
+ *
+ * By convention, handles are indexes into an array of file descriptors
+ * that are sent alongside a DBus message.  If you're not interacting
+ * with DBus, you probably don't need them.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (HANDLE, handle, gint32)
+
+/**
+ * g_variant_new_double:
+ * @floating: a #gdouble floating point value
+ * @returns: a floating reference to a new double #GVariant instance
+ *
+ * Creates a new double #GVariant instance.
+ *
+ * Since: 2.24
+ **/
+/**
+ * g_variant_get_double:
+ * @value: a double #GVariant instance
+ * @returns: a #gdouble
+ *
+ * Returns the double precision floating point value of @value.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than %G_VARIANT_TYPE_DOUBLE.
+ *
+ * Since: 2.24
+ **/
+NUMERIC_TYPE (DOUBLE, double, gdouble)
+
+/* Container type Constructor / Deconstructors {{{1 */
+/**
+ * g_variant_new_maybe:
+ * @child_type: (allow-none): the #GVariantType of the child, or %NULL
+ * @child: (allow-none): the child value, or %NULL
+ * @returns: a floating reference to a new #GVariant maybe instance
+ *
+ * Depending on if @child is %NULL, either wraps @child inside of a
+ * maybe container or creates a Nothing instance for the given @type.
+ *
+ * At least one of @child_type and @child must be non-%NULL.
+ * If @child_type is non-%NULL then it must be a definite type.
+ * If they are both non-%NULL then @child_type must be the type
+ * of @child.
+ *
+ * If @child is a floating reference (see g_variant_ref_sink()), the new
+ * instance takes ownership of @child.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_maybe (const GVariantType *child_type,
+                     GVariant           *child)
+{
+  GVariantType *maybe_type;
+  GVariant *value;
+
+  g_return_val_if_fail (child_type == NULL || g_variant_type_is_definite
+                        (child_type), 0);
+  g_return_val_if_fail (child_type != NULL || child != NULL, NULL);
+  g_return_val_if_fail (child_type == NULL || child == NULL ||
+                        g_variant_is_of_type (child, child_type),
+                        NULL);
+
+  if (child_type == NULL)
+    child_type = g_variant_get_type (child);
+
+  maybe_type = g_variant_type_new_maybe (child_type);
+
+  if (child != NULL)
+    {
+      GVariant **children;
+      gboolean trusted;
+
+      children = g_new (GVariant *, 1);
+      children[0] = g_variant_ref_sink (child);
+      trusted = g_variant_is_trusted (children[0]);
+
+      value = g_variant_new_from_children (maybe_type, children, 1, trusted);
+    }
+  else
+    value = g_variant_new_from_children (maybe_type, NULL, 0, TRUE);
+
+  g_variant_type_free (maybe_type);
+
+  return value;
+}
+
+/**
+ * g_variant_get_maybe:
+ * @value: a maybe-typed value
+ * @returns: (allow-none): the contents of @value, or %NULL
+ *
+ * Given a maybe-typed #GVariant instance, extract its value.  If the
+ * value is Nothing, then this function returns %NULL.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_get_maybe (GVariant *value)
+{
+  TYPE_CHECK (value, G_VARIANT_TYPE_MAYBE, NULL);
+
+  if (g_variant_n_children (value))
+    return g_variant_get_child_value (value, 0);
+
+  return NULL;
+}
+
+/**
+ * g_variant_new_variant:
+ * @value: a #GVariance instance
+ * @returns: a floating reference to a new variant #GVariant instance
+ *
+ * Boxes @value.  The result is a #GVariant instance representing a
+ * variant containing the original value.
+ *
+ * If @child is a floating reference (see g_variant_ref_sink()), the new
+ * instance takes ownership of @child.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_variant (GVariant *value)
+{
+  g_return_val_if_fail (value != NULL, NULL);
+
+  g_variant_ref_sink (value);
+
+  return g_variant_new_from_children (G_VARIANT_TYPE_VARIANT,
+                                      g_memdup (&value, sizeof value),
+                                      1, g_variant_is_trusted (value));
+}
+
+/**
+ * g_variant_get_variant:
+ * @value: a variant #GVariance instance
+ * @returns: the item contained in the variant
+ *
+ * Unboxes @value.  The result is the #GVariant instance that was
+ * contained in @value.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_get_variant (GVariant *value)
+{
+  TYPE_CHECK (value, G_VARIANT_TYPE_VARIANT, NULL);
+
+  return g_variant_get_child_value (value, 0);
+}
+
+/**
+ * g_variant_new_array:
+ * @child_type: (allow-none): the element type of the new array
+ * @children: (allow-none) (array length=n_children): an array of
+ *            #GVariant pointers, the children
+ * @n_children: the length of @children
+ * @returns: a floating reference to a new #GVariant array
+ *
+ * Creates a new #GVariant array from @children.
+ *
+ * @child_type must be non-%NULL if @n_children is zero.  Otherwise, the
+ * child type is determined by inspecting the first element of the
+ * @children array.  If @child_type is non-%NULL then it must be a
+ * definite type.
+ *
+ * The items of the array are taken from the @children array.  No entry
+ * in the @children array may be %NULL.
+ *
+ * All items in the array must have the same type, which must be the
+ * same as @child_type, if given.
+ *
+ * If the @children are floating references (see g_variant_ref_sink()), the
+ * new instance takes ownership of them as if via g_variant_ref_sink().
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_array (const GVariantType *child_type,
+                     GVariant * const   *children,
+                     gsize               n_children)
+{
+  GVariantType *array_type;
+  GVariant **my_children;
+  gboolean trusted;
+  GVariant *value;
+  gsize i;
+
+  g_return_val_if_fail (n_children > 0 || child_type != NULL, NULL);
+  g_return_val_if_fail (n_children == 0 || children != NULL, NULL);
+  g_return_val_if_fail (child_type == NULL ||
+                        g_variant_type_is_definite (child_type), NULL);
+
+  my_children = g_new (GVariant *, n_children);
+  trusted = TRUE;
+
+  if (child_type == NULL)
+    child_type = g_variant_get_type (children[0]);
+  array_type = g_variant_type_new_array (child_type);
+
+  for (i = 0; i < n_children; i++)
+    {
+      TYPE_CHECK (children[i], child_type, NULL);
+      my_children[i] = g_variant_ref_sink (children[i]);
+      trusted &= g_variant_is_trusted (children[i]);
+    }
+
+  value = g_variant_new_from_children (array_type, my_children,
+                                       n_children, trusted);
+  g_variant_type_free (array_type);
+
+  return value;
+}
+
+/*< private >
+ * g_variant_make_tuple_type:
+ * @children: (array length=n_children): an array of GVariant *
+ * @n_children: the length of @children
+ *
+ * Return the type of a tuple containing @children as its items.
+ **/
+static GVariantType *
+g_variant_make_tuple_type (GVariant * const *children,
+                           gsize             n_children)
+{
+  const GVariantType **types;
+  GVariantType *type;
+  gsize i;
+
+  types = g_new (const GVariantType *, n_children);
+
+  for (i = 0; i < n_children; i++)
+    types[i] = g_variant_get_type (children[i]);
+
+  type = g_variant_type_new_tuple (types, n_children);
+  g_free (types);
+
+  return type;
+}
+
+/**
+ * g_variant_new_tuple:
+ * @children: (array length=n_children): the items to make the tuple out of
+ * @n_children: the length of @children
+ * @returns: a floating reference to a new #GVariant tuple
+ *
+ * Creates a new tuple #GVariant out of the items in @children.  The
+ * type is determined from the types of @children.  No entry in the
+ * @children array may be %NULL.
+ *
+ * If @n_children is 0 then the unit tuple is constructed.
+ *
+ * If the @children are floating references (see g_variant_ref_sink()), the
+ * new instance takes ownership of them as if via g_variant_ref_sink().
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_tuple (GVariant * const *children,
+                     gsize             n_children)
+{
+  GVariantType *tuple_type;
+  GVariant **my_children;
+  gboolean trusted;
+  GVariant *value;
+  gsize i;
+
+  g_return_val_if_fail (n_children == 0 || children != NULL, NULL);
+
+  my_children = g_new (GVariant *, n_children);
+  trusted = TRUE;
+
+  for (i = 0; i < n_children; i++)
+    {
+      my_children[i] = g_variant_ref_sink (children[i]);
+      trusted &= g_variant_is_trusted (children[i]);
+    }
+
+  tuple_type = g_variant_make_tuple_type (children, n_children);
+  value = g_variant_new_from_children (tuple_type, my_children,
+                                       n_children, trusted);
+  g_variant_type_free (tuple_type);
+
+  return value;
+}
+
+/*< private >
+ * g_variant_make_dict_entry_type:
+ * @key: a #GVariant, the key
+ * @val: a #GVariant, the value
+ *
+ * Return the type of a dictionary entry containing @key and @val as its
+ * children.
+ **/
+static GVariantType *
+g_variant_make_dict_entry_type (GVariant *key,
+                                GVariant *val)
+{
+  return g_variant_type_new_dict_entry (g_variant_get_type (key),
+                                        g_variant_get_type (val));
+}
+
+/**
+ * g_variant_new_dict_entry:
+ * @key: a basic #GVariant, the key
+ * @value: a #GVariant, the value
+ * @returns: a floating reference to a new dictionary entry #GVariant
+ *
+ * Creates a new dictionary entry #GVariant.  @key and @value must be
+ * non-%NULL.
+ *
+ * @key must be a value of a basic type (ie: not a container).
+ *
+ * If the @key or @value are floating references (see g_variant_ref_sink()),
+ * the new instance takes ownership of them as if via g_variant_ref_sink().
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_dict_entry (GVariant *key,
+                          GVariant *value)
+{
+  GVariantType *dict_type;
+  GVariant **children;
+  gboolean trusted;
+
+  g_return_val_if_fail (key != NULL && value != NULL, NULL);
+  g_return_val_if_fail (!g_variant_is_container (key), NULL);
+
+  children = g_new (GVariant *, 2);
+  children[0] = g_variant_ref_sink (key);
+  children[1] = g_variant_ref_sink (value);
+  trusted = g_variant_is_trusted (key) && g_variant_is_trusted (value);
+
+  dict_type = g_variant_make_dict_entry_type (key, value);
+  value = g_variant_new_from_children (dict_type, children, 2, trusted);
+  g_variant_type_free (dict_type);
+
+  return value;
+}
+
+/**
+ * g_variant_get_fixed_array:
+ * @value: a #GVariant array with fixed-sized elements
+ * @n_elements: a pointer to the location to store the number of items
+ * @element_size: the size of each element
+ * @returns: (array length=n_elements): a pointer to the fixed array
+ *
+ * Provides access to the serialised data for an array of fixed-sized
+ * items.
+ *
+ * @value must be an array with fixed-sized elements.  Numeric types are
+ * fixed-size as are tuples containing only other fixed-sized types.
+ *
+ * @element_size must be the size of a single element in the array.  For
+ * example, if calling this function for an array of 32 bit integers,
+ * you might say <code>sizeof (gint32)</code>.  This value isn't used
+ * except for the purpose of a double-check that the form of the
+ * seralised data matches the caller's expectation.
+ *
+ * @n_elements, which must be non-%NULL is set equal to the number of
+ * items in the array.
+ *
+ * Since: 2.24
+ **/
+gconstpointer
+g_variant_get_fixed_array (GVariant *value,
+                           gsize    *n_elements,
+                           gsize     element_size)
+{
+  GVariantTypeInfo *array_info;
+  gsize array_element_size;
+  gconstpointer data;
+  gsize size;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_ARRAY, NULL);
+
+  g_return_val_if_fail (n_elements != NULL, NULL);
+  g_return_val_if_fail (element_size > 0, NULL);
+
+  array_info = g_variant_get_type_info (value);
+  g_variant_type_info_query_element (array_info, NULL, &array_element_size);
+
+  g_return_val_if_fail (array_element_size, NULL);
+
+  if G_UNLIKELY (array_element_size != element_size)
+    {
+      if (array_element_size)
+        g_critical ("g_variant_get_fixed_array: assertion "
+                    "`g_variant_array_has_fixed_size (value, element_size)' "
+                    "failed: array size %"G_GSIZE_FORMAT" does not match "
+                    "given element_size %"G_GSIZE_FORMAT".",
+                    array_element_size, element_size);
+      else
+        g_critical ("g_variant_get_fixed_array: assertion "
+                    "`g_variant_array_has_fixed_size (value, element_size)' "
+                    "failed: array does not have fixed size.");
+    }
+
+  data = g_variant_get_data (value);
+  size = g_variant_get_size (value);
+
+  if (size % element_size)
+    *n_elements = 0;
+  else
+    *n_elements = size / element_size;
+
+  if (*n_elements)
+    return data;
+
+  return NULL;
+}
+
+/* String type constructor/getters/validation {{{1 */
+/**
+ * g_variant_new_string:
+ * @string: a normal utf8 nul-terminated string
+ * @returns: a floating reference to a new string #GVariant instance
+ *
+ * Creates a string #GVariant with the contents of @string.
+ *
+ * @string must be valid utf8.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_string (const gchar *string)
+{
+  g_return_val_if_fail (string != NULL, NULL);
+  g_return_val_if_fail (g_utf8_validate (string, -1, NULL), NULL);
+
+  return g_variant_new_from_trusted (G_VARIANT_TYPE_STRING,
+                                     string, strlen (string) + 1);
+}
+
+/**
+ * g_variant_new_object_path:
+ * @object_path: a normal C nul-terminated string
+ * @returns: a floating reference to a new object path #GVariant instance
+ *
+ * Creates a DBus object path #GVariant with the contents of @string.
+ * @string must be a valid DBus object path.  Use
+ * g_variant_is_object_path() if you're not sure.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_object_path (const gchar *object_path)
+{
+  g_return_val_if_fail (g_variant_is_object_path (object_path), NULL);
+
+  return g_variant_new_from_trusted (G_VARIANT_TYPE_OBJECT_PATH,
+                                     object_path, strlen (object_path) + 1);
+}
+
+/**
+ * g_variant_is_object_path:
+ * @string: a normal C nul-terminated string
+ * @returns: %TRUE if @string is a DBus object path
+ *
+ * Determines if a given string is a valid DBus object path.  You
+ * should ensure that a string is a valid DBus object path before
+ * passing it to g_variant_new_object_path().
+ *
+ * A valid object path starts with '/' followed by zero or more
+ * sequences of characters separated by '/' characters.  Each sequence
+ * must contain only the characters "[A-Z][a-z][0-9]_".  No sequence
+ * (including the one following the final '/' character) may be empty.
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_is_object_path (const gchar *string)
+{
+  g_return_val_if_fail (string != NULL, FALSE);
+
+  return g_variant_serialiser_is_object_path (string, strlen (string) + 1);
+}
+
+/**
+ * g_variant_new_signature:
+ * @signature: a normal C nul-terminated string
+ * @returns: a floating reference to a new signature #GVariant instance
+ *
+ * Creates a DBus type signature #GVariant with the contents of
+ * @string.  @string must be a valid DBus type signature.  Use
+ * g_variant_is_signature() if you're not sure.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_signature (const gchar *signature)
+{
+  g_return_val_if_fail (g_variant_is_signature (signature), NULL);
+
+  return g_variant_new_from_trusted (G_VARIANT_TYPE_SIGNATURE,
+                                     signature, strlen (signature) + 1);
+}
+
+/**
+ * g_variant_is_signature:
+ * @string: a normal C nul-terminated string
+ * @returns: %TRUE if @string is a DBus type signature
+ *
+ * Determines if a given string is a valid DBus type signature.  You
+ * should ensure that a string is a valid DBus type signature before
+ * passing it to g_variant_new_signature().
+ *
+ * DBus type signatures consist of zero or more definite #GVariantType
+ * strings in sequence.
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_is_signature (const gchar *string)
+{
+  g_return_val_if_fail (string != NULL, FALSE);
+
+  return g_variant_serialiser_is_signature (string, strlen (string) + 1);
+}
+
+/**
+ * g_variant_get_string:
+ * @value: a string #GVariant instance
+ * @length: (allow-none) (default NULL) (out): a pointer to a #gsize,
+ *          to store the length
+ * @returns: the constant string, utf8 encoded
+ *
+ * Returns the string value of a #GVariant instance with a string
+ * type.  This includes the types %G_VARIANT_TYPE_STRING,
+ * %G_VARIANT_TYPE_OBJECT_PATH and %G_VARIANT_TYPE_SIGNATURE.
+ *
+ * The string will always be utf8 encoded.
+ *
+ * If @length is non-%NULL then the length of the string (in bytes) is
+ * returned there.  For trusted values, this information is already
+ * known.  For untrusted values, a strlen() will be performed.
+ *
+ * It is an error to call this function with a @value of any type
+ * other than those three.
+ *
+ * The return value remains valid as long as @value exists.
+ *
+ * Since: 2.24
+ **/
+const gchar *
+g_variant_get_string (GVariant *value,
+                      gsize    *length)
+{
+  gconstpointer data;
+  gsize size;
+
+  g_return_val_if_fail (value != NULL, NULL);
+  g_return_val_if_fail (
+    g_variant_is_of_type (value, G_VARIANT_TYPE_STRING) ||
+    g_variant_is_of_type (value, G_VARIANT_TYPE_OBJECT_PATH) ||
+    g_variant_is_of_type (value, G_VARIANT_TYPE_SIGNATURE), NULL);
+
+  data = g_variant_get_data (value);
+  size = g_variant_get_size (value);
+
+  if (!g_variant_is_trusted (value))
+    {
+      switch (g_variant_classify (value))
+        {
+        case G_VARIANT_CLASS_STRING:
+          if (g_variant_serialiser_is_string (data, size))
+            break;
+
+          data = "";
+          size = 1;
+          break;
+
+        case G_VARIANT_CLASS_OBJECT_PATH:
+          if (g_variant_serialiser_is_object_path (data, size))
+            break;
+
+          data = "/";
+          size = 2;
+          break;
+
+        case G_VARIANT_CLASS_SIGNATURE:
+          if (g_variant_serialiser_is_signature (data, size))
+            break;
+
+          data = "";
+          size = 1;
+          break;
+
+        default:
+          g_assert_not_reached ();
+        }
+    }
+
+  if (length)
+    *length = size - 1;
+
+  return data;
+}
+
+/**
+ * g_variant_dup_string:
+ * @value: a string #GVariant instance
+ * @length: a pointer to a #gsize, to store the length
+ * @returns: a newly allocated string, utf8 encoded
+ *
+ * Similar to g_variant_get_string() except that instead of returning
+ * a constant string, the string is duplicated.
+ *
+ * The string will always be utf8 encoded.
+ *
+ * The return value must be freed using g_free().
+ *
+ * Since: 2.24
+ **/
+gchar *
+g_variant_dup_string (GVariant *value,
+                      gsize    *length)
+{
+  return g_strdup (g_variant_get_string (value, length));
+}
+
+/**
+ * g_variant_new_strv:
+ * @strv: (array length=length) (element-type utf8): an array of strings
+ * @length: the length of @strv, or -1
+ * @returns: a new floating #GVariant instance
+ *
+ * Constructs an array of strings #GVariant from the given array of
+ * strings.
+ *
+ * If @length is -1 then @strv is %NULL-terminated.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_strv (const gchar * const *strv,
+                    gssize               length)
+{
+  GVariant **strings;
+  gsize i;
+
+  g_return_val_if_fail (length == 0 || strv != NULL, NULL);
+
+  if (length < 0)
+    length = g_strv_length ((gchar **) strv);
+
+  strings = g_new (GVariant *, length);
+  for (i = 0; i < length; i++)
+    strings[i] = g_variant_ref_sink (g_variant_new_string (strv[i]));
+
+  return g_variant_new_from_children (G_VARIANT_TYPE_STRING_ARRAY,
+                                      strings, length, TRUE);
+}
+
+/**
+ * g_variant_get_strv:
+ * @value: an array of strings #GVariant
+ * @length: (allow-none): the length of the result, or %NULL
+ * @returns: (array length=length) (transfer container): an array of constant
+ * strings
+ *
+ * Gets the contents of an array of strings #GVariant.  This call
+ * makes a shallow copy; the return result should be released with
+ * g_free(), but the individual strings must not be modified.
+ *
+ * If @length is non-%NULL then the number of elements in the result
+ * is stored there.  In any case, the resulting array will be
+ * %NULL-terminated.
+ *
+ * For an empty array, @length will be set to 0 and a pointer to a
+ * %NULL pointer will be returned.
+ *
+ * Since: 2.24
+ **/
+const gchar **
+g_variant_get_strv (GVariant *value,
+                    gsize    *length)
+{
+  const gchar **strv;
+  gsize n;
+  gsize i;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_STRING_ARRAY, NULL);
+
+  g_variant_get_data (value);
+  n = g_variant_n_children (value);
+  strv = g_new (const gchar *, n + 1);
+
+  for (i = 0; i < n; i++)
+    {
+      GVariant *string;
+
+      string = g_variant_get_child_value (value, i);
+      strv[i] = g_variant_get_string (string, NULL);
+      g_variant_unref (string);
+    }
+  strv[i] = NULL;
+
+  if (length)
+    *length = n;
+
+  return strv;
+}
+
+/**
+ * g_variant_dup_strv:
+ * @value: an array of strings #GVariant
+ * @length: (allow-none): the length of the result, or %NULL
+ * @returns: (array length=length): an array of strings
+ *
+ * Gets the contents of an array of strings #GVariant.  This call
+ * makes a deep copy; the return result should be released with
+ * g_strfreev().
+ *
+ * If @length is non-%NULL then the number of elements in the result
+ * is stored there.  In any case, the resulting array will be
+ * %NULL-terminated.
+ *
+ * For an empty array, @length will be set to 0 and a pointer to a
+ * %NULL pointer will be returned.
+ *
+ * Since: 2.24
+ **/
+gchar **
+g_variant_dup_strv (GVariant *value,
+                    gsize    *length)
+{
+  gchar **strv;
+  gsize n;
+  gsize i;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_STRING_ARRAY, NULL);
+
+  n = g_variant_n_children (value);
+  strv = g_new (gchar *, n + 1);
+
+  for (i = 0; i < n; i++)
+    {
+      GVariant *string;
+
+      string = g_variant_get_child_value (value, i);
+      strv[i] = g_variant_dup_string (string, NULL);
+      g_variant_unref (string);
+    }
+  strv[i] = NULL;
+
+  if (length)
+    *length = n;
+
+  return strv;
+}
+
+/**
+ * g_variant_new_bytestring:
+ * @string: a normal nul-terminated string in no particular encoding
+ * @returns: a floating reference to a new bytestring #GVariant instance
+ *
+ * Creates an array-of-bytes #GVariant with the contents of @string.
+ * This function is just like g_variant_new_string() except that the
+ * string need not be valid utf8.
+ *
+ * The nul terminator character at the end of the string is stored in
+ * the array.
+ *
+ * Since: 2.26
+ **/
+GVariant *
+g_variant_new_bytestring (const gchar *string)
+{
+  g_return_val_if_fail (string != NULL, NULL);
+
+  return g_variant_new_from_trusted (G_VARIANT_TYPE_BYTESTRING,
+                                     string, strlen (string) + 1);
+}
+
+/**
+ * g_variant_get_bytestring:
+ * @value: an array-of-bytes #GVariant instance
+ * @returns: the constant string
+ *
+ * Returns the string value of a #GVariant instance with an
+ * array-of-bytes type.  The string has no particular encoding.
+ *
+ * If the array does not end with a nul terminator character, the empty
+ * string is returned.  For this reason, you can always trust that a
+ * non-%NULL nul-terminated string will be returned by this function.
+ *
+ * If the array contains a nul terminator character somewhere other than
+ * the last byte then the returned string is the string, up to the first
+ * such nul character.
+ *
+ * It is an error to call this function with a @value that is not an
+ * array of bytes.
+ *
+ * The return value remains valid as long as @value exists.
+ *
+ * Since: 2.26
+ **/
+const gchar *
+g_variant_get_bytestring (GVariant *value)
+{
+  const gchar *string;
+  gsize size;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_BYTESTRING, NULL);
+
+  /* Won't be NULL since this is an array type */
+  string = g_variant_get_data (value);
+  size = g_variant_get_size (value);
+
+  if (size && string[size - 1] == '\0')
+    return string;
+  else
+    return "";
+}
+
+/**
+ * g_variant_dup_bytestring:
+ * @value: an array-of-bytes #GVariant instance
+ * @length: (allow-none) (default NULL): a pointer to a #gsize, to store
+ *          the length (not including the nul terminator)
+ * @returns: a newly allocated string
+ *
+ * Similar to g_variant_get_bytestring() except that instead of
+ * returning a constant string, the string is duplicated.
+ *
+ * The return value must be freed using g_free().
+ *
+ * Since: 2.26
+ **/
+gchar *
+g_variant_dup_bytestring (GVariant *value,
+                          gsize    *length)
+{
+  const gchar *original = g_variant_get_bytestring (value);
+  gsize size;
+
+  /* don't crash in case get_bytestring() had an assert failure */
+  if (original == NULL)
+    return NULL;
+
+  size = strlen (original);
+
+  if (length)
+    *length = size;
+
+  return g_memdup (original, size + 1);
+}
+
+/**
+ * g_variant_new_bytestring_array:
+ * @strv: (array length=length): an array of strings
+ * @length: the length of @strv, or -1
+ * @returns: a new floating #GVariant instance
+ *
+ * Constructs an array of bytestring #GVariant from the given array of
+ * strings.
+ *
+ * If @length is -1 then @strv is %NULL-terminated.
+ *
+ * Since: 2.26
+ **/
+GVariant *
+g_variant_new_bytestring_array (const gchar * const *strv,
+                                gssize               length)
+{
+  GVariant **strings;
+  gsize i;
+
+  g_return_val_if_fail (length == 0 || strv != NULL, NULL);
+
+  if (length < 0)
+    length = g_strv_length ((gchar **) strv);
+
+  strings = g_new (GVariant *, length);
+  for (i = 0; i < length; i++)
+    strings[i] = g_variant_ref_sink (g_variant_new_bytestring (strv[i]));
+
+  return g_variant_new_from_children (G_VARIANT_TYPE_BYTESTRING_ARRAY,
+                                      strings, length, TRUE);
+}
+
+/**
+ * g_variant_get_bytestring_array:
+ * @value: an array of array of bytes #GVariant ('aay')
+ * @length: (allow-none): the length of the result, or %NULL
+ * @returns: (array length=length): an array of constant strings
+ *
+ * Gets the contents of an array of array of bytes #GVariant.  This call
+ * makes a shallow copy; the return result should be released with
+ * g_free(), but the individual strings must not be modified.
+ *
+ * If @length is non-%NULL then the number of elements in the result is
+ * stored there.  In any case, the resulting array will be
+ * %NULL-terminated.
+ *
+ * For an empty array, @length will be set to 0 and a pointer to a
+ * %NULL pointer will be returned.
+ *
+ * Since: 2.26
+ **/
+const gchar **
+g_variant_get_bytestring_array (GVariant *value,
+                                gsize    *length)
+{
+  const gchar **strv;
+  gsize n;
+  gsize i;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_BYTESTRING_ARRAY, NULL);
+
+  g_variant_get_data (value);
+  n = g_variant_n_children (value);
+  strv = g_new (const gchar *, n + 1);
+
+  for (i = 0; i < n; i++)
+    {
+      GVariant *string;
+
+      string = g_variant_get_child_value (value, i);
+      strv[i] = g_variant_get_bytestring (string);
+      g_variant_unref (string);
+    }
+  strv[i] = NULL;
+
+  if (length)
+    *length = n;
+
+  return strv;
+}
+
+/**
+ * g_variant_dup_bytestring_array:
+ * @value: an array of array of bytes #GVariant ('aay')
+ * @length: (allow-none): the length of the result, or %NULL
+ * @returns: (array length=length): an array of strings
+ *
+ * Gets the contents of an array of array of bytes #GVariant.  This call
+ * makes a deep copy; the return result should be released with
+ * g_strfreev().
+ *
+ * If @length is non-%NULL then the number of elements in the result is
+ * stored there.  In any case, the resulting array will be
+ * %NULL-terminated.
+ *
+ * For an empty array, @length will be set to 0 and a pointer to a
+ * %NULL pointer will be returned.
+ *
+ * Since: 2.26
+ **/
+gchar **
+g_variant_dup_bytestring_array (GVariant *value,
+                                gsize    *length)
+{
+  gchar **strv;
+  gsize n;
+  gsize i;
+
+  TYPE_CHECK (value, G_VARIANT_TYPE_BYTESTRING_ARRAY, NULL);
+
+  g_variant_get_data (value);
+  n = g_variant_n_children (value);
+  strv = g_new (gchar *, n + 1);
+
+  for (i = 0; i < n; i++)
+    {
+      GVariant *string;
+
+      string = g_variant_get_child_value (value, i);
+      strv[i] = g_variant_dup_bytestring (string, NULL);
+      g_variant_unref (string);
+    }
+  strv[i] = NULL;
+
+  if (length)
+    *length = n;
+
+  return strv;
+}
+
+/* Type checking and querying {{{1 */
+/**
+ * g_variant_get_type:
+ * @value: a #GVariant
+ * @returns: a #GVariantType
+ *
+ * Determines the type of @value.
+ *
+ * The return value is valid for the lifetime of @value and must not
+ * be freed.
+ *
+ * Since: 2.24
+ **/
+const GVariantType *
+g_variant_get_type (GVariant *value)
+{
+  GVariantTypeInfo *type_info;
+
+  g_return_val_if_fail (value != NULL, NULL);
+
+  type_info = g_variant_get_type_info (value);
+
+  return (GVariantType *) g_variant_type_info_get_type_string (type_info);
+}
+
+/**
+ * g_variant_get_type_string:
+ * @value: a #GVariant
+ * @returns: the type string for the type of @value
+ *
+ * Returns the type string of @value.  Unlike the result of calling
+ * g_variant_type_peek_string(), this string is nul-terminated.  This
+ * string belongs to #GVariant and must not be freed.
+ *
+ * Since: 2.24
+ **/
+const gchar *
+g_variant_get_type_string (GVariant *value)
+{
+  GVariantTypeInfo *type_info;
+
+  g_return_val_if_fail (value != NULL, NULL);
+
+  type_info = g_variant_get_type_info (value);
+
+  return g_variant_type_info_get_type_string (type_info);
+}
+
+/**
+ * g_variant_is_of_type:
+ * @value: a #GVariant instance
+ * @type: a #GVariantType
+ * @returns: %TRUE if the type of @value matches @type
+ *
+ * Checks if a value has a type matching the provided type.
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_is_of_type (GVariant           *value,
+                      const GVariantType *type)
+{
+  return g_variant_type_is_subtype_of (g_variant_get_type (value), type);
+}
+
+/**
+ * g_variant_is_container:
+ * @value: a #GVariant instance
+ * @returns: %TRUE if @value is a container
+ *
+ * Checks if @value is a container.
+ */
+gboolean
+g_variant_is_container (GVariant *value)
+{
+  return g_variant_type_is_container (g_variant_get_type (value));
+}
+
+
+/**
+ * g_variant_classify:
+ * @value: a #GVariant
+ * @returns: the #GVariantClass of @value
+ *
+ * Classifies @value according to its top-level type.
+ *
+ * Since: 2.24
+ **/
+/**
+ * GVariantClass:
+ * @G_VARIANT_CLASS_BOOLEAN: The #GVariant is a boolean.
+ * @G_VARIANT_CLASS_BYTE: The #GVariant is a byte.
+ * @G_VARIANT_CLASS_INT16: The #GVariant is a signed 16 bit integer.
+ * @G_VARIANT_CLASS_UINT16: The #GVariant is an unsigned 16 bit integer.
+ * @G_VARIANT_CLASS_INT32: The #GVariant is a signed 32 bit integer.
+ * @G_VARIANT_CLASS_UINT32: The #GVariant is an unsigned 32 bit integer.
+ * @G_VARIANT_CLASS_INT64: The #GVariant is a signed 64 bit integer.
+ * @G_VARIANT_CLASS_UINT64: The #GVariant is an unsigned 64 bit integer.
+ * @G_VARIANT_CLASS_HANDLE: The #GVariant is a file handle index.
+ * @G_VARIANT_CLASS_DOUBLE: The #GVariant is a double precision floating 
+ *                          point value.
+ * @G_VARIANT_CLASS_STRING: The #GVariant is a normal string.
+ * @G_VARIANT_CLASS_OBJECT_PATH: The #GVariant is a DBus object path 
+ *                               string.
+ * @G_VARIANT_CLASS_SIGNATURE: The #GVariant is a DBus signature string.
+ * @G_VARIANT_CLASS_VARIANT: The #GVariant is a variant.
+ * @G_VARIANT_CLASS_MAYBE: The #GVariant is a maybe-typed value.
+ * @G_VARIANT_CLASS_ARRAY: The #GVariant is an array.
+ * @G_VARIANT_CLASS_TUPLE: The #GVariant is a tuple.
+ * @G_VARIANT_CLASS_DICT_ENTRY: The #GVariant is a dictionary entry.
+ *
+ * The range of possible top-level types of #GVariant instances.
+ *
+ * Since: 2.24
+ **/
+GVariantClass
+g_variant_classify (GVariant *value)
+{
+  g_return_val_if_fail (value != NULL, 0);
+
+  return *g_variant_get_type_string (value);
+}
+
+/* Pretty printer {{{1 */
+/**
+ * g_variant_print_string:
+ * @value: a #GVariant
+ * @string: (allow-none) (default NULL): a #GString, or %NULL
+ * @type_annotate: %TRUE if type information should be included in
+ *                 the output
+ * @returns: a #GString containing the string
+ *
+ * Behaves as g_variant_print(), but operates on a #GString.
+ *
+ * If @string is non-%NULL then it is appended to and returned.  Else,
+ * a new empty #GString is allocated and it is returned.
+ *
+ * Since: 2.24
+ **/
+GString *
+g_variant_print_string (GVariant *value,
+                        GString  *string,
+                        gboolean  type_annotate)
+{
+  if G_UNLIKELY (string == NULL)
+    string = g_string_new (NULL);
+
+  switch (g_variant_classify (value))
+    {
+    case G_VARIANT_CLASS_MAYBE:
+      if (type_annotate)
+        g_string_append_printf (string, "@%s ",
+                                g_variant_get_type_string (value));
+
+      if (g_variant_n_children (value))
+        {
+          gchar *printed_child;
+          GVariant *element;
+
+          /* Nested maybes:
+           *
+           * Consider the case of the type "mmi".  In this case we could
+           * write "just just 4", but "4" alone is totally unambiguous,
+           * so we try to drop "just" where possible.
+           *
+           * We have to be careful not to always drop "just", though,
+           * since "nothing" needs to be distinguishable from "just
+           * nothing".  The case where we need to ensure we keep the
+           * "just" is actually exactly the case where we have a nested
+           * Nothing.
+           *
+           * Instead of searching for that nested Nothing, we just print
+           * the contained value into a separate string and see if we
+           * end up with "nothing" at the end of it.  If so, we need to
+           * add "just" at our level.
+           */
+          element = g_variant_get_child_value (value, 0);
+          printed_child = g_variant_print (element, FALSE);
+          g_variant_unref (element);
+
+          if (g_str_has_suffix (printed_child, "nothing"))
+            g_string_append (string, "just ");
+          g_string_append (string, printed_child);
+          g_free (printed_child);
+        }
+      else
+        g_string_append (string, "nothing");
+
+      break;
+
+    case G_VARIANT_CLASS_ARRAY:
+      /* it's an array so the first character of the type string is 'a'
+       *
+       * if the first two characters are 'ay' then it's a bytestring.
+       * under certain conditions we print those as strings.
+       */
+      if (g_variant_get_type_string (value)[1] == 'y')
+        {
+          const gchar *str;
+          gsize size;
+          gsize i;
+
+          /* first determine if it is a byte string.
+           * that's when there's a single nul character: at the end.
+           */
+          str = g_variant_get_data (value);
+          size = g_variant_get_size (value);
+
+          for (i = 0; i < size; i++)
+            if (str[i] == '\0')
+              break;
+
+          /* first nul byte is the last byte -> it's a byte string. */
+          if (i == size - 1)
+            {
+              gchar *escaped = g_strescape (str, NULL);
+
+              /* use double quotes only if a ' is in the string */
+              if (strchr (str, '\''))
+                g_string_append_printf (string, "b\"%s\"", escaped);
+              else
+                g_string_append_printf (string, "b'%s'", escaped);
+
+              g_free (escaped);
+              break;
+            }
+
+          else
+            /* fall through and handle normally... */;
+        }
+
+      /*
+       * if the first two characters are 'a{' then it's an array of
+       * dictionary entries (ie: a dictionary) so we print that
+       * differently.
+       */
+      if (g_variant_get_type_string (value)[1] == '{')
+        /* dictionary */
+        {
+          const gchar *comma = "";
+          gsize n, i;
+
+          if ((n = g_variant_n_children (value)) == 0)
+            {
+              if (type_annotate)
+                g_string_append_printf (string, "@%s ",
+                                        g_variant_get_type_string (value));
+              g_string_append (string, "{}");
+              break;
+            }
+
+          g_string_append_c (string, '{');
+          for (i = 0; i < n; i++)
+            {
+              GVariant *entry, *key, *val;
+
+              g_string_append (string, comma);
+              comma = ", ";
+
+              entry = g_variant_get_child_value (value, i);
+              key = g_variant_get_child_value (entry, 0);
+              val = g_variant_get_child_value (entry, 1);
+              g_variant_unref (entry);
+
+              g_variant_print_string (key, string, type_annotate);
+              g_variant_unref (key);
+              g_string_append (string, ": ");
+              g_variant_print_string (val, string, type_annotate);
+              g_variant_unref (val);
+              type_annotate = FALSE;
+            }
+          g_string_append_c (string, '}');
+        }
+      else
+        /* normal (non-dictionary) array */
+        {
+          const gchar *comma = "";
+          gsize n, i;
+
+          if ((n = g_variant_n_children (value)) == 0)
+            {
+              if (type_annotate)
+                g_string_append_printf (string, "@%s ",
+                                        g_variant_get_type_string (value));
+              g_string_append (string, "[]");
+              break;
+            }
+
+          g_string_append_c (string, '[');
+          for (i = 0; i < n; i++)
+            {
+              GVariant *element;
+
+              g_string_append (string, comma);
+              comma = ", ";
+
+              element = g_variant_get_child_value (value, i);
+
+              g_variant_print_string (element, string, type_annotate);
+              g_variant_unref (element);
+              type_annotate = FALSE;
+            }
+          g_string_append_c (string, ']');
+        }
+
+      break;
+
+    case G_VARIANT_CLASS_TUPLE:
+      {
+        gsize n, i;
+
+        n = g_variant_n_children (value);
+
+        g_string_append_c (string, '(');
+        for (i = 0; i < n; i++)
+          {
+            GVariant *element;
+
+            element = g_variant_get_child_value (value, i);
+            g_variant_print_string (element, string, type_annotate);
+            g_string_append (string, ", ");
+            g_variant_unref (element);
+          }
+
+        /* for >1 item:  remove final ", "
+         * for 1 item:   remove final " ", but leave the ","
+         * for 0 items:  there is only "(", so remove nothing
+         */
+        g_string_truncate (string, string->len - (n > 0) - (n > 1));
+        g_string_append_c (string, ')');
+      }
+      break;
+
+    case G_VARIANT_CLASS_DICT_ENTRY:
+      {
+        GVariant *element;
+
+        g_string_append_c (string, '{');
+
+        element = g_variant_get_child_value (value, 0);
+        g_variant_print_string (element, string, type_annotate);
+        g_variant_unref (element);
+
+        g_string_append (string, ", ");
+
+        element = g_variant_get_child_value (value, 1);
+        g_variant_print_string (element, string, type_annotate);
+        g_variant_unref (element);
+
+        g_string_append_c (string, '}');
+      }
+      break;
+
+    case G_VARIANT_CLASS_VARIANT:
+      {
+        GVariant *child = g_variant_get_variant (value);
+
+        /* Always annotate types in nested variants, because they are
+         * (by nature) of variable type.
+         */
+        g_string_append_c (string, '<');
+        g_variant_print_string (child, string, TRUE);
+        g_string_append_c (string, '>');
+
+        g_variant_unref (child);
+      }
+      break;
+
+    case G_VARIANT_CLASS_BOOLEAN:
+      if (g_variant_get_boolean (value))
+        g_string_append (string, "true");
+      else
+        g_string_append (string, "false");
+      break;
+
+    case G_VARIANT_CLASS_STRING:
+      {
+        const gchar *str = g_variant_get_string (value, NULL);
+        gunichar quote = strchr (str, '\'') ? '"' : '\'';
+
+        g_string_append_c (string, quote);
+
+        while (*str)
+          {
+            gunichar c = g_utf8_get_char (str);
+
+            if (c == quote || c == '\\')
+              g_string_append_c (string, '\\');
+
+            if (g_unichar_isprint (c))
+              g_string_append_unichar (string, c);
+
+            else
+              {
+                g_string_append_c (string, '\\');
+                if (c < 0x10000)
+                  switch (c)
+                    {
+                    case '\a':
+                      g_string_append_c (string, 'a');
+                      break;
+
+                    case '\b':
+                      g_string_append_c (string, 'b');
+                      break;
+
+                    case '\f':
+                      g_string_append_c (string, 'f');
+                      break;
+
+                    case '\n':
+                      g_string_append_c (string, 'n');
+                      break;
+
+                    case '\r':
+                      g_string_append_c (string, 'r');
+                      break;
+
+                    case '\t':
+                      g_string_append_c (string, 't');
+                      break;
+
+                    case '\v':
+                      g_string_append_c (string, 'v');
+                      break;
+
+                    default:
+                      g_string_append_printf (string, "u%04x", c);
+                      break;
+                    }
+                 else
+                   g_string_append_printf (string, "U%08x", c);
+              }
+
+            str = g_utf8_next_char (str);
+          }
+
+        g_string_append_c (string, quote);
+      }
+      break;
+
+    case G_VARIANT_CLASS_BYTE:
+      if (type_annotate)
+        g_string_append (string, "byte ");
+      g_string_append_printf (string, "0x%02x",
+                              g_variant_get_byte (value));
+      break;
+
+    case G_VARIANT_CLASS_INT16:
+      if (type_annotate)
+        g_string_append (string, "int16 ");
+      g_string_append_printf (string, "%"G_GINT16_FORMAT,
+                              g_variant_get_int16 (value));
+      break;
+
+    case G_VARIANT_CLASS_UINT16:
+      if (type_annotate)
+        g_string_append (string, "uint16 ");
+      g_string_append_printf (string, "%"G_GUINT16_FORMAT,
+                              g_variant_get_uint16 (value));
+      break;
+
+    case G_VARIANT_CLASS_INT32:
+      /* Never annotate this type because it is the default for numbers
+       * (and this is a *pretty* printer)
+       */
+      g_string_append_printf (string, "%"G_GINT32_FORMAT,
+                              g_variant_get_int32 (value));
+      break;
+
+    case G_VARIANT_CLASS_HANDLE:
+      if (type_annotate)
+        g_string_append (string, "handle ");
+      g_string_append_printf (string, "%"G_GINT32_FORMAT,
+                              g_variant_get_handle (value));
+      break;
+
+    case G_VARIANT_CLASS_UINT32:
+      if (type_annotate)
+        g_string_append (string, "uint32 ");
+      g_string_append_printf (string, "%"G_GUINT32_FORMAT,
+                              g_variant_get_uint32 (value));
+      break;
+
+    case G_VARIANT_CLASS_INT64:
+      if (type_annotate)
+        g_string_append (string, "int64 ");
+      g_string_append_printf (string, "%"G_GINT64_FORMAT,
+                              g_variant_get_int64 (value));
+      break;
+
+    case G_VARIANT_CLASS_UINT64:
+      if (type_annotate)
+        g_string_append (string, "uint64 ");
+      g_string_append_printf (string, "%"G_GUINT64_FORMAT,
+                              g_variant_get_uint64 (value));
+      break;
+
+    case G_VARIANT_CLASS_DOUBLE:
+      {
+        gchar buffer[100];
+        gint i;
+
+        g_ascii_dtostr (buffer, sizeof buffer, g_variant_get_double (value));
+
+        for (i = 0; buffer[i]; i++)
+          if (buffer[i] == '.' || buffer[i] == 'e' ||
+              buffer[i] == 'n' || buffer[i] == 'N')
+            break;
+
+        /* if there is no '.' or 'e' in the float then add one */
+        if (buffer[i] == '\0')
+          {
+            buffer[i++] = '.';
+            buffer[i++] = '0';
+            buffer[i++] = '\0';
+          }
+
+        g_string_append (string, buffer);
+      }
+      break;
+
+    case G_VARIANT_CLASS_OBJECT_PATH:
+      if (type_annotate)
+        g_string_append (string, "objectpath ");
+      g_string_append_printf (string, "\'%s\'",
+                              g_variant_get_string (value, NULL));
+      break;
+
+    case G_VARIANT_CLASS_SIGNATURE:
+      if (type_annotate)
+        g_string_append (string, "signature ");
+      g_string_append_printf (string, "\'%s\'",
+                              g_variant_get_string (value, NULL));
+      break;
+
+    default:
+      g_assert_not_reached ();
+  }
+
+  return string;
+}
+
+/**
+ * g_variant_print:
+ * @value: a #GVariant
+ * @type_annotate: %TRUE if type information should be included in
+ *                 the output
+ * @returns: a newly-allocated string holding the result.
+ *
+ * Pretty-prints @value in the format understood by g_variant_parse().
+ *
+ * If @type_annotate is %TRUE, then type information is included in
+ * the output.
+ */
+gchar *
+g_variant_print (GVariant *value,
+                 gboolean  type_annotate)
+{
+  return g_string_free (g_variant_print_string (value, NULL, type_annotate),
+                        FALSE);
+};
+
+/* Hash, Equal, Compare {{{1 */
+/**
+ * g_variant_hash:
+ * @value: (type GVariant): a basic #GVariant value as a #gconstpointer
+ * @returns: a hash value corresponding to @value
+ *
+ * Generates a hash value for a #GVariant instance.
+ *
+ * The output of this function is guaranteed to be the same for a given
+ * value only per-process.  It may change between different processor
+ * architectures or even different versions of GLib.  Do not use this
+ * function as a basis for building protocols or file formats.
+ *
+ * The type of @value is #gconstpointer only to allow use of this
+ * function with #GHashTable.  @value must be a #GVariant.
+ *
+ * Since: 2.24
+ **/
+guint
+g_variant_hash (gconstpointer value_)
+{
+  GVariant *value = (GVariant *) value_;
+
+  switch (g_variant_classify (value))
+    {
+    case G_VARIANT_CLASS_STRING:
+    case G_VARIANT_CLASS_OBJECT_PATH:
+    case G_VARIANT_CLASS_SIGNATURE:
+      return g_str_hash (g_variant_get_string (value, NULL));
+
+    case G_VARIANT_CLASS_BOOLEAN:
+      /* this is a very odd thing to hash... */
+      return g_variant_get_boolean (value);
+
+    case G_VARIANT_CLASS_BYTE:
+      return g_variant_get_byte (value);
+
+    case G_VARIANT_CLASS_INT16:
+    case G_VARIANT_CLASS_UINT16:
+      {
+        const guint16 *ptr;
+
+        ptr = g_variant_get_data (value);
+
+        if (ptr)
+          return *ptr;
+        else
+          return 0;
+      }
+
+    case G_VARIANT_CLASS_INT32:
+    case G_VARIANT_CLASS_UINT32:
+    case G_VARIANT_CLASS_HANDLE:
+      {
+        const guint *ptr;
+
+        ptr = g_variant_get_data (value);
+
+        if (ptr)
+          return *ptr;
+        else
+          return 0;
+      }
+
+    case G_VARIANT_CLASS_INT64:
+    case G_VARIANT_CLASS_UINT64:
+    case G_VARIANT_CLASS_DOUBLE:
+      /* need a separate case for these guys because otherwise
+       * performance could be quite bad on big endian systems
+       */
+      {
+        const guint *ptr;
+
+        ptr = g_variant_get_data (value);
+
+        if (ptr)
+          return ptr[0] + ptr[1];
+        else
+          return 0;
+      }
+
+    default:
+      g_return_val_if_fail (!g_variant_is_container (value), 0);
+      g_assert_not_reached ();
+    }
+}
+
+/**
+ * g_variant_equal:
+ * @one: (type GVariant): a #GVariant instance
+ * @two: (type GVariant): a #GVariant instance
+ * @returns: %TRUE if @one and @two are equal
+ *
+ * Checks if @one and @two have the same type and value.
+ *
+ * The types of @one and @two are #gconstpointer only to allow use of
+ * this function with #GHashTable.  They must each be a #GVariant.
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_equal (gconstpointer one,
+                 gconstpointer two)
+{
+  gboolean equal;
+
+  g_return_val_if_fail (one != NULL && two != NULL, FALSE);
+
+  if (g_variant_get_type_info ((GVariant *) one) !=
+      g_variant_get_type_info ((GVariant *) two))
+    return FALSE;
+
+  /* if both values are trusted to be in their canonical serialised form
+   * then a simple memcmp() of their serialised data will answer the
+   * question.
+   *
+   * if not, then this might generate a false negative (since it is
+   * possible for two different byte sequences to represent the same
+   * value).  for now we solve this by pretty-printing both values and
+   * comparing the result.
+   */
+  if (g_variant_is_trusted ((GVariant *) one) &&
+      g_variant_is_trusted ((GVariant *) two))
+    {
+      gconstpointer data_one, data_two;
+      gsize size_one, size_two;
+
+      size_one = g_variant_get_size ((GVariant *) one);
+      size_two = g_variant_get_size ((GVariant *) two);
+
+      if (size_one != size_two)
+        return FALSE;
+
+      data_one = g_variant_get_data ((GVariant *) one);
+      data_two = g_variant_get_data ((GVariant *) two);
+
+      equal = memcmp (data_one, data_two, size_one) == 0;
+    }
+  else
+    {
+      gchar *strone, *strtwo;
+
+      strone = g_variant_print ((GVariant *) one, FALSE);
+      strtwo = g_variant_print ((GVariant *) two, FALSE);
+      equal = strcmp (strone, strtwo) == 0;
+      g_free (strone);
+      g_free (strtwo);
+    }
+
+  return equal;
+}
+
+/**
+ * g_variant_compare:
+ * @one: (type GVariant): a basic-typed #GVariant instance
+ * @two: (type GVariant): a #GVariant instance of the same type
+ * @returns: negative value if a &lt; b;
+ *           zero if a = b;
+ *           positive value if a &gt; b.
+ *
+ * Compares @one and @two.
+ *
+ * The types of @one and @two are #gconstpointer only to allow use of
+ * this function with #GTree, #GPtrArray, etc.  They must each be a
+ * #GVariant.
+ *
+ * Comparison is only defined for basic types (ie: booleans, numbers,
+ * strings).  For booleans, %FALSE is less than %TRUE.  Numbers are
+ * ordered in the usual way.  Strings are in ASCII lexographical order.
+ *
+ * It is a programmer error to attempt to compare container values or
+ * two values that have types that are not exactly equal.  For example,
+ * you can not compare a 32-bit signed integer with a 32-bit unsigned
+ * integer.  Also note that this function is not particularly
+ * well-behaved when it comes to comparison of doubles; in particular,
+ * the handling of incomparable values (ie: NaN) is undefined.
+ *
+ * If you only require an equality comparison, g_variant_equal() is more
+ * general.
+ *
+ * Since: 2.26
+ **/
+gint
+g_variant_compare (gconstpointer one,
+                   gconstpointer two)
+{
+  GVariant *a = (GVariant *) one;
+  GVariant *b = (GVariant *) two;
+
+  g_return_val_if_fail (g_variant_classify (a) == g_variant_classify (b), 0);
+
+  switch (g_variant_classify (a))
+    {
+    case G_VARIANT_CLASS_BYTE:
+      return ((gint) g_variant_get_byte (a)) -
+             ((gint) g_variant_get_byte (b));
+
+    case G_VARIANT_CLASS_INT16:
+      return ((gint) g_variant_get_int16 (a)) -
+             ((gint) g_variant_get_int16 (b));
+
+    case G_VARIANT_CLASS_UINT16:
+      return ((gint) g_variant_get_uint16 (a)) -
+             ((gint) g_variant_get_uint16 (b));
+
+    case G_VARIANT_CLASS_INT32:
+      {
+        gint32 a_val = g_variant_get_int32 (a);
+        gint32 b_val = g_variant_get_int32 (b);
+
+        return (a_val == b_val) ? 0 : (a_val > b_val) ? 1 : -1;
+      }
+
+    case G_VARIANT_CLASS_UINT32:
+      {
+        guint32 a_val = g_variant_get_uint32 (a);
+        guint32 b_val = g_variant_get_uint32 (b);
+
+        return (a_val == b_val) ? 0 : (a_val > b_val) ? 1 : -1;
+      }
+
+    case G_VARIANT_CLASS_INT64:
+      {
+        gint64 a_val = g_variant_get_int64 (a);
+        gint64 b_val = g_variant_get_int64 (b);
+
+        return (a_val == b_val) ? 0 : (a_val > b_val) ? 1 : -1;
+      }
+
+    case G_VARIANT_CLASS_UINT64:
+      {
+        guint64 a_val = g_variant_get_int32 (a);
+        guint64 b_val = g_variant_get_int32 (b);
+
+        return (a_val == b_val) ? 0 : (a_val > b_val) ? 1 : -1;
+      }
+
+    case G_VARIANT_CLASS_DOUBLE:
+      {
+        gdouble a_val = g_variant_get_double (a);
+        gdouble b_val = g_variant_get_double (b);
+
+        return (a_val == b_val) ? 0 : (a_val > b_val) ? 1 : -1;
+      }
+
+    case G_VARIANT_CLASS_STRING:
+    case G_VARIANT_CLASS_OBJECT_PATH:
+    case G_VARIANT_CLASS_SIGNATURE:
+      return strcmp (g_variant_get_string (a, NULL),
+                     g_variant_get_string (b, NULL));
+
+    default:
+      g_return_val_if_fail (!g_variant_is_container (a), 0);
+      g_assert_not_reached ();
+    }
+}
+
+/* GVariantIter {{{1 */
+/**
+ * GVariantIter:
+ *
+ * #GVariantIter is an opaque data structure and can only be accessed
+ * using the following functions.
+ **/
+struct stack_iter
+{
+  GVariant *value;
+  gssize n, i;
+
+  const gchar *loop_format;
+
+  gsize padding[3];
+  gsize magic;
+};
+
+G_STATIC_ASSERT (sizeof (struct stack_iter) <= sizeof (GVariantIter));
+
+struct heap_iter
+{
+  struct stack_iter iter;
+
+  GVariant *value_ref;
+  gsize magic;
+};
+
+#define GVSI(i)                 ((struct stack_iter *) (i))
+#define GVHI(i)                 ((struct heap_iter *) (i))
+#define GVSI_MAGIC              ((gsize) 3579507750u)
+#define GVHI_MAGIC              ((gsize) 1450270775u)
+#define is_valid_iter(i)        (i != NULL && \
+                                 GVSI(i)->magic == GVSI_MAGIC)
+#define is_valid_heap_iter(i)   (GVHI(i)->magic == GVHI_MAGIC && \
+                                 is_valid_iter(i))
+
+/**
+ * g_variant_iter_new:
+ * @value: a container #GVariant
+ * @returns: a new heap-allocated #GVariantIter
+ *
+ * Creates a heap-allocated #GVariantIter for iterating over the items
+ * in @value.
+ *
+ * Use g_variant_iter_free() to free the return value when you no longer
+ * need it.
+ *
+ * A reference is taken to @value and will be released only when
+ * g_variant_iter_free() is called.
+ *
+ * Since: 2.24
+ **/
+GVariantIter *
+g_variant_iter_new (GVariant *value)
+{
+  GVariantIter *iter;
+
+  iter = (GVariantIter *) g_slice_new (struct heap_iter);
+  GVHI(iter)->value_ref = g_variant_ref (value);
+  GVHI(iter)->magic = GVHI_MAGIC;
+
+  g_variant_iter_init (iter, value);
+
+  return iter;
+}
+
+/**
+ * g_variant_iter_init:
+ * @iter: a pointer to a #GVariantIter
+ * @value: a container #GVariant
+ * @returns: the number of items in @value
+ *
+ * Initialises (without allocating) a #GVariantIter.  @iter may be
+ * completely uninitialised prior to this call; its old value is
+ * ignored.
+ *
+ * The iterator remains valid for as long as @value exists, and need not
+ * be freed in any way.
+ *
+ * Since: 2.24
+ **/
+gsize
+g_variant_iter_init (GVariantIter *iter,
+                     GVariant     *value)
+{
+  GVSI(iter)->magic = GVSI_MAGIC;
+  GVSI(iter)->value = value;
+  GVSI(iter)->n = g_variant_n_children (value);
+  GVSI(iter)->i = -1;
+  GVSI(iter)->loop_format = NULL;
+
+  return GVSI(iter)->n;
+}
+
+/**
+ * g_variant_iter_copy:
+ * @iter: a #GVariantIter
+ * @returns: a new heap-allocated #GVariantIter
+ *
+ * Creates a new heap-allocated #GVariantIter to iterate over the
+ * container that was being iterated over by @iter.  Iteration begins on
+ * the new iterator from the current position of the old iterator but
+ * the two copies are independent past that point.
+ *
+ * Use g_variant_iter_free() to free the return value when you no longer
+ * need it.
+ *
+ * A reference is taken to the container that @iter is iterating over
+ * and will be releated only when g_variant_iter_free() is called.
+ *
+ * Since: 2.24
+ **/
+GVariantIter *
+g_variant_iter_copy (GVariantIter *iter)
+{
+  GVariantIter *copy;
+
+  g_return_val_if_fail (is_valid_iter (iter), 0);
+
+  copy = g_variant_iter_new (GVSI(iter)->value);
+  GVSI(copy)->i = GVSI(iter)->i;
+
+  return copy;
+}
+
+/**
+ * g_variant_iter_n_children:
+ * @iter: a #GVariantIter
+ * @returns: the number of children in the container
+ *
+ * Queries the number of child items in the container that we are
+ * iterating over.  This is the total number of items -- not the number
+ * of items remaining.
+ *
+ * This function might be useful for preallocation of arrays.
+ *
+ * Since: 2.24
+ **/
+gsize
+g_variant_iter_n_children (GVariantIter *iter)
+{
+  g_return_val_if_fail (is_valid_iter (iter), 0);
+
+  return GVSI(iter)->n;
+}
+
+/**
+ * g_variant_iter_free:
+ * @iter: a heap-allocated #GVariantIter
+ *
+ * Frees a heap-allocated #GVariantIter.  Only call this function on
+ * iterators that were returned by g_variant_iter_new() or
+ * g_variant_iter_copy().
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_iter_free (GVariantIter *iter)
+{
+  g_return_if_fail (is_valid_heap_iter (iter));
+
+  g_variant_unref (GVHI(iter)->value_ref);
+  GVHI(iter)->magic = 0;
+
+  g_slice_free (struct heap_iter, GVHI(iter));
+}
+
+/**
+ * g_variant_iter_next_value:
+ * @iter: a #GVariantIter
+ * @returns: (allow-none): a #GVariant, or %NULL
+ *
+ * Gets the next item in the container.  If no more items remain then
+ * %NULL is returned.
+ *
+ * Use g_variant_unref() to drop your reference on the return value when
+ * you no longer need it.
+ *
+ * <example>
+ *  <title>Iterating with g_variant_iter_next_value()</title>
+ *  <programlisting>
+ *   /<!-- -->* recursively iterate a container *<!-- -->/
+ *   void
+ *   iterate_container_recursive (GVariant *container)
+ *   {
+ *     GVariantIter iter;
+ *     GVariant *child;
+ *
+ *     g_variant_iter_init (&iter, dictionary);
+ *     while ((child = g_variant_iter_next_value (&iter)))
+ *       {
+ *         g_print ("type '%s'\n", g_variant_get_type_string (child));
+ *
+ *         if (g_variant_is_container (child))
+ *           iterate_container_recursive (child);
+ *
+ *         g_variant_unref (child);
+ *       }
+ *   }
+ * </programlisting>
+ * </example>
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_iter_next_value (GVariantIter *iter)
+{
+  g_return_val_if_fail (is_valid_iter (iter), FALSE);
+
+  if G_UNLIKELY (GVSI(iter)->i >= GVSI(iter)->n)
+    {
+      g_critical ("g_variant_iter_next_value: must not be called again "
+                  "after NULL has already been returned.");
+      return NULL;
+    }
+
+  GVSI(iter)->i++;
+
+  if (GVSI(iter)->i < GVSI(iter)->n)
+    return g_variant_get_child_value (GVSI(iter)->value, GVSI(iter)->i);
+
+  return NULL;
+}
+
+/* GVariantBuilder {{{1 */
+/**
+ * GVariantBuilder:
+ *
+ * A utility type for constructing container-type #GVariant instances.
+ *
+ * This is an opaque structure and may only be accessed using the
+ * following functions.
+ *
+ * #GVariantBuilder is not threadsafe in any way.  Do not attempt to
+ * access it from more than one thread.
+ **/
+
+struct stack_builder
+{
+  GVariantBuilder *parent;
+  GVariantType *type;
+
+  /* type constraint explicitly specified by 'type'.
+   * for tuple types, this moves along as we add more items.
+   */
+  const GVariantType *expected_type;
+
+  /* type constraint implied by previous array item.
+   */
+  const GVariantType *prev_item_type;
+
+  /* constraints on the number of children.  max = -1 for unlimited. */
+  gsize min_items;
+  gsize max_items;
+
+  /* dynamically-growing pointer array */
+  GVariant **children;
+  gsize allocated_children;
+  gsize offset;
+
+  /* set to '1' if all items in the container will have the same type
+   * (ie: maybe, array, variant) '0' if not (ie: tuple, dict entry)
+   */
+  guint uniform_item_types : 1;
+
+  /* set to '1' initially and changed to '0' if an untrusted value is
+   * added
+   */
+  guint trusted : 1;
+
+  gsize magic;
+};
+
+G_STATIC_ASSERT (sizeof (struct stack_builder) <= sizeof (GVariantBuilder));
+
+struct heap_builder
+{
+  GVariantBuilder builder;
+  gsize magic;
+
+  gint ref_count;
+};
+
+#define GVSB(b)                  ((struct stack_builder *) (b))
+#define GVHB(b)                  ((struct heap_builder *) (b))
+#define GVSB_MAGIC               ((gsize) 1033660112u)
+#define GVHB_MAGIC               ((gsize) 3087242682u)
+#define is_valid_builder(b)      (b != NULL && \
+                                  GVSB(b)->magic == GVSB_MAGIC)
+#define is_valid_heap_builder(b) (GVHB(b)->magic == GVHB_MAGIC)
+
+/**
+ * g_variant_builder_new:
+ * @type: a container type
+ * @returns: a #GVariantBuilder
+ *
+ * Allocates and initialises a new #GVariantBuilder.
+ *
+ * You should call g_variant_builder_unref() on the return value when it
+ * is no longer needed.  The memory will not be automatically freed by
+ * any other call.
+ *
+ * In most cases it is easier to place a #GVariantBuilder directly on
+ * the stack of the calling function and initialise it with
+ * g_variant_builder_init().
+ *
+ * Since: 2.24
+ **/
+GVariantBuilder *
+g_variant_builder_new (const GVariantType *type)
+{
+  GVariantBuilder *builder;
+
+  builder = (GVariantBuilder *) g_slice_new (struct heap_builder);
+  g_variant_builder_init (builder, type);
+  GVHB(builder)->magic = GVHB_MAGIC;
+  GVHB(builder)->ref_count = 1;
+
+  return builder;
+}
+
+/**
+ * g_variant_builder_unref:
+ * @builder: a #GVariantBuilder allocated by g_variant_builder_new()
+ *
+ * Decreases the reference count on @builder.
+ *
+ * In the event that there are no more references, releases all memory
+ * associated with the #GVariantBuilder.
+ *
+ * Don't call this on stack-allocated #GVariantBuilder instances or bad
+ * things will happen.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_unref (GVariantBuilder *builder)
+{
+  g_return_if_fail (is_valid_heap_builder (builder));
+
+  if (--GVHB(builder)->ref_count)
+    return;
+
+  g_variant_builder_clear (builder);
+  GVHB(builder)->magic = 0;
+
+  g_slice_free (struct heap_builder, GVHB(builder));
+}
+
+/**
+ * g_variant_builder_ref:
+ * @builder: a #GVariantBuilder allocated by g_variant_builder_new()
+ * @returns: a new reference to @builder
+ *
+ * Increases the reference count on @builder.
+ *
+ * Don't call this on stack-allocated #GVariantBuilder instances or bad
+ * things will happen.
+ *
+ * Since: 2.24
+ **/
+GVariantBuilder *
+g_variant_builder_ref (GVariantBuilder *builder)
+{
+  g_return_val_if_fail (is_valid_heap_builder (builder), NULL);
+
+  GVHB(builder)->ref_count++;
+
+  return builder;
+}
+
+/**
+ * g_variant_builder_clear:
+ * @builder: a #GVariantBuilder
+ *
+ * Releases all memory associated with a #GVariantBuilder without
+ * freeing the #GVariantBuilder structure itself.
+ *
+ * It typically only makes sense to do this on a stack-allocated
+ * #GVariantBuilder if you want to abort building the value part-way
+ * through.  This function need not be called if you call
+ * g_variant_builder_end() and it also doesn't need to be called on
+ * builders allocated with g_variant_builder_new (see
+ * g_variant_builder_free() for that).
+ *
+ * This function leaves the #GVariantBuilder structure set to all-zeros.
+ * It is valid to call this function on either an initialised
+ * #GVariantBuilder or one that is set to all-zeros but it is not valid
+ * to call this function on uninitialised memory.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_clear (GVariantBuilder *builder)
+{
+  gsize i;
+
+  if (GVSB(builder)->magic == 0)
+    /* all-zeros case */
+    return;
+
+  g_return_if_fail (is_valid_builder (builder));
+
+  g_variant_type_free (GVSB(builder)->type);
+
+  for (i = 0; i < GVSB(builder)->offset; i++)
+    g_variant_unref (GVSB(builder)->children[i]);
+
+  g_free (GVSB(builder)->children);
+
+  if (GVSB(builder)->parent)
+    {
+      g_variant_builder_clear (GVSB(builder)->parent);
+      g_slice_free (GVariantBuilder, GVSB(builder)->parent);
+    }
+
+  memset (builder, 0, sizeof (GVariantBuilder));
+}
+
+/**
+ * g_variant_builder_init:
+ * @builder: a #GVariantBuilder
+ * @type: a container type
+ *
+ * Initialises a #GVariantBuilder structure.
+ *
+ * @type must be non-%NULL.  It specifies the type of container to
+ * construct.  It can be an indefinite type such as
+ * %G_VARIANT_TYPE_ARRAY or a definite type such as "as" or "(ii)".
+ * Maybe, array, tuple, dictionary entry and variant-typed values may be
+ * constructed.
+ *
+ * After the builder is initialised, values are added using
+ * g_variant_builder_add_value() or g_variant_builder_add().
+ *
+ * After all the child values are added, g_variant_builder_end() frees
+ * the memory associated with the builder and returns the #GVariant that
+ * was created.
+ *
+ * This function completely ignores the previous contents of @builder.
+ * On one hand this means that it is valid to pass in completely
+ * uninitialised memory.  On the other hand, this means that if you are
+ * initialising over top of an existing #GVariantBuilder you need to
+ * first call g_variant_builder_clear() in order to avoid leaking
+ * memory.
+ *
+ * You must not call g_variant_builder_ref() or
+ * g_variant_builder_unref() on a #GVariantBuilder that was initialised
+ * with this function.  If you ever pass a reference to a
+ * #GVariantBuilder outside of the control of your own code then you
+ * should assume that the person receiving that reference may try to use
+ * reference counting; you should use g_variant_builder_new() instead of
+ * this function.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_init (GVariantBuilder    *builder,
+                        const GVariantType *type)
+{
+  g_return_if_fail (type != NULL);
+  g_return_if_fail (g_variant_type_is_container (type));
+
+  memset (builder, 0, sizeof (GVariantBuilder));
+
+  GVSB(builder)->type = g_variant_type_copy (type);
+  GVSB(builder)->magic = GVSB_MAGIC;
+  GVSB(builder)->trusted = TRUE;
+
+  switch (*(const gchar *) type)
+    {
+    case G_VARIANT_CLASS_VARIANT:
+      GVSB(builder)->uniform_item_types = TRUE;
+      GVSB(builder)->allocated_children = 1;
+      GVSB(builder)->expected_type = NULL;
+      GVSB(builder)->min_items = 1;
+      GVSB(builder)->max_items = 1;
+      break;
+
+    case G_VARIANT_CLASS_ARRAY:
+      GVSB(builder)->uniform_item_types = TRUE;
+      GVSB(builder)->allocated_children = 8;
+      GVSB(builder)->expected_type =
+        g_variant_type_element (GVSB(builder)->type);
+      GVSB(builder)->min_items = 0;
+      GVSB(builder)->max_items = -1;
+      break;
+
+    case G_VARIANT_CLASS_MAYBE:
+      GVSB(builder)->uniform_item_types = TRUE;
+      GVSB(builder)->allocated_children = 1;
+      GVSB(builder)->expected_type =
+        g_variant_type_element (GVSB(builder)->type);
+      GVSB(builder)->min_items = 0;
+      GVSB(builder)->max_items = 1;
+      break;
+
+    case G_VARIANT_CLASS_DICT_ENTRY:
+      GVSB(builder)->uniform_item_types = FALSE;
+      GVSB(builder)->allocated_children = 2;
+      GVSB(builder)->expected_type =
+        g_variant_type_key (GVSB(builder)->type);
+      GVSB(builder)->min_items = 2;
+      GVSB(builder)->max_items = 2;
+      break;
+
+    case 'r': /* G_VARIANT_TYPE_TUPLE was given */
+      GVSB(builder)->uniform_item_types = FALSE;
+      GVSB(builder)->allocated_children = 8;
+      GVSB(builder)->expected_type = NULL;
+      GVSB(builder)->min_items = 0;
+      GVSB(builder)->max_items = -1;
+      break;
+
+    case G_VARIANT_CLASS_TUPLE: /* a definite tuple type was given */
+      GVSB(builder)->allocated_children = g_variant_type_n_items (type);
+      GVSB(builder)->expected_type =
+        g_variant_type_first (GVSB(builder)->type);
+      GVSB(builder)->min_items = GVSB(builder)->allocated_children;
+      GVSB(builder)->max_items = GVSB(builder)->allocated_children;
+      GVSB(builder)->uniform_item_types = FALSE;
+      break;
+
+    default:
+      g_assert_not_reached ();
+   }
+
+  GVSB(builder)->children = g_new (GVariant *,
+                                   GVSB(builder)->allocated_children);
+}
+
+static void
+g_variant_builder_make_room (struct stack_builder *builder)
+{
+  if (builder->offset == builder->allocated_children)
+    {
+      builder->allocated_children *= 2;
+      builder->children = g_renew (GVariant *, builder->children,
+                                   builder->allocated_children);
+    }
+}
+
+/**
+ * g_variant_builder_add_value:
+ * @builder: a #GVariantBuilder
+ * @value: a #GVariant
+ *
+ * Adds @value to @builder.
+ *
+ * It is an error to call this function in any way that would create an
+ * inconsistent value to be constructed.  Some examples of this are
+ * putting different types of items into an array, putting the wrong
+ * types or number of items in a tuple, putting more than one value into
+ * a variant, etc.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_add_value (GVariantBuilder *builder,
+                             GVariant        *value)
+{
+  g_return_if_fail (is_valid_builder (builder));
+  g_return_if_fail (GVSB(builder)->offset < GVSB(builder)->max_items);
+  g_return_if_fail (!GVSB(builder)->expected_type ||
+                    g_variant_is_of_type (value,
+                                          GVSB(builder)->expected_type));
+  g_return_if_fail (!GVSB(builder)->prev_item_type ||
+                    g_variant_is_of_type (value,
+                                          GVSB(builder)->prev_item_type));
+
+  GVSB(builder)->trusted &= g_variant_is_trusted (value);
+
+  if (!GVSB(builder)->uniform_item_types)
+    {
+      /* advance our expected type pointers */
+      if (GVSB(builder)->expected_type)
+        GVSB(builder)->expected_type =
+          g_variant_type_next (GVSB(builder)->expected_type);
+
+      if (GVSB(builder)->prev_item_type)
+        GVSB(builder)->prev_item_type =
+          g_variant_type_next (GVSB(builder)->prev_item_type);
+    }
+  else
+    GVSB(builder)->prev_item_type = g_variant_get_type (value);
+
+  g_variant_builder_make_room (GVSB(builder));
+
+  GVSB(builder)->children[GVSB(builder)->offset++] =
+    g_variant_ref_sink (value);
+}
+
+/**
+ * g_variant_builder_open:
+ * @builder: a #GVariantBuilder
+ * @type: a #GVariantType
+ *
+ * Opens a subcontainer inside the given @builder.  When done adding
+ * items to the subcontainer, g_variant_builder_close() must be called.
+ *
+ * It is an error to call this function in any way that would cause an
+ * inconsistent value to be constructed (ie: adding too many values or
+ * a value of an incorrect type).
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_open (GVariantBuilder    *builder,
+                        const GVariantType *type)
+{
+  GVariantBuilder *parent;
+
+  g_return_if_fail (is_valid_builder (builder));
+  g_return_if_fail (GVSB(builder)->offset < GVSB(builder)->max_items);
+  g_return_if_fail (!GVSB(builder)->expected_type ||
+                    g_variant_type_is_subtype_of (type,
+                                                  GVSB(builder)->expected_type));
+  g_return_if_fail (!GVSB(builder)->prev_item_type ||
+                    g_variant_type_is_subtype_of (GVSB(builder)->prev_item_type,
+                                                  type));
+
+  parent = g_slice_dup (GVariantBuilder, builder);
+  g_variant_builder_init (builder, type);
+  GVSB(builder)->parent = parent;
+
+  /* push the prev_item_type down into the subcontainer */
+  if (GVSB(parent)->prev_item_type)
+    {
+      if (!GVSB(builder)->uniform_item_types)
+        /* tuples and dict entries */
+        GVSB(builder)->prev_item_type =
+          g_variant_type_first (GVSB(parent)->prev_item_type);
+
+      else if (!g_variant_type_is_variant (GVSB(builder)->type))
+        /* maybes and arrays */
+        GVSB(builder)->prev_item_type =
+          g_variant_type_element (GVSB(parent)->prev_item_type);
+    }
+}
+
+/**
+ * g_variant_builder_close:
+ * @builder: a #GVariantBuilder
+ *
+ * Closes the subcontainer inside the given @builder that was opened by
+ * the most recent call to g_variant_builder_open().
+ *
+ * It is an error to call this function in any way that would create an
+ * inconsistent value to be constructed (ie: too few values added to the
+ * subcontainer).
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_close (GVariantBuilder *builder)
+{
+  GVariantBuilder *parent;
+
+  g_return_if_fail (is_valid_builder (builder));
+  g_return_if_fail (GVSB(builder)->parent != NULL);
+
+  parent = GVSB(builder)->parent;
+  GVSB(builder)->parent = NULL;
+
+  g_variant_builder_add_value (parent, g_variant_builder_end (builder));
+  *builder = *parent;
+
+  g_slice_free (GVariantBuilder, parent);
+}
+
+/*< private >
+ * g_variant_make_maybe_type:
+ * @element: a #GVariant
+ *
+ * Return the type of a maybe containing @element.
+ */
+static GVariantType *
+g_variant_make_maybe_type (GVariant *element)
+{
+  return g_variant_type_new_maybe (g_variant_get_type (element));
+}
+
+/*< private >
+ * g_variant_make_array_type:
+ * @element: a #GVariant
+ *
+ * Return the type of an array containing @element.
+ */
+static GVariantType *
+g_variant_make_array_type (GVariant *element)
+{
+  return g_variant_type_new_array (g_variant_get_type (element));
+}
+
+/**
+ * g_variant_builder_end:
+ * @builder: a #GVariantBuilder
+ * @returns: (transfer none): a new, floating, #GVariant
+ *
+ * Ends the builder process and returns the constructed value.
+ *
+ * It is not permissible to use @builder in any way after this call
+ * except for reference counting operations (in the case of a
+ * heap-allocated #GVariantBuilder) or by reinitialising it with
+ * g_variant_builder_init() (in the case of stack-allocated).
+ *
+ * It is an error to call this function in any way that would create an
+ * inconsistent value to be constructed (ie: insufficient number of
+ * items added to a container with a specific number of children
+ * required).  It is also an error to call this function if the builder
+ * was created with an indefinite array or maybe type and no children
+ * have been added; in this case it is impossible to infer the type of
+ * the empty array.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_builder_end (GVariantBuilder *builder)
+{
+  GVariantType *my_type;
+  GVariant *value;
+
+  g_return_val_if_fail (is_valid_builder (builder), NULL);
+  g_return_val_if_fail (GVSB(builder)->offset >= GVSB(builder)->min_items,
+                        NULL);
+  g_return_val_if_fail (!GVSB(builder)->uniform_item_types ||
+                        GVSB(builder)->prev_item_type != NULL ||
+                        g_variant_type_is_definite (GVSB(builder)->type),
+                        NULL);
+
+  if (g_variant_type_is_definite (GVSB(builder)->type))
+    my_type = g_variant_type_copy (GVSB(builder)->type);
+
+  else if (g_variant_type_is_maybe (GVSB(builder)->type))
+    my_type = g_variant_make_maybe_type (GVSB(builder)->children[0]);
+
+  else if (g_variant_type_is_array (GVSB(builder)->type))
+    my_type = g_variant_make_array_type (GVSB(builder)->children[0]);
+
+  else if (g_variant_type_is_tuple (GVSB(builder)->type))
+    my_type = g_variant_make_tuple_type (GVSB(builder)->children,
+                                         GVSB(builder)->offset);
+
+  else if (g_variant_type_is_dict_entry (GVSB(builder)->type))
+    my_type = g_variant_make_dict_entry_type (GVSB(builder)->children[0],
+                                              GVSB(builder)->children[1]);
+  else
+    g_assert_not_reached ();
+
+  value = g_variant_new_from_children (my_type,
+                                       g_renew (GVariant *,
+                                                GVSB(builder)->children,
+                                                GVSB(builder)->offset),
+                                       GVSB(builder)->offset,
+                                       GVSB(builder)->trusted);
+  GVSB(builder)->children = NULL;
+  GVSB(builder)->offset = 0;
+
+  g_variant_builder_clear (builder);
+  g_variant_type_free (my_type);
+
+  return value;
+}
+
+/* Format strings {{{1 */
+/*< private >
+ * g_variant_format_string_scan:
+ * @string: a string that may be prefixed with a format string
+ * @limit: (allow-none) (default NULL): a pointer to the end of @string,
+ *         or %NULL
+ * @endptr: (allow-none) (default NULL): location to store the end pointer,
+ *          or %NULL
+ * @returns: %TRUE if there was a valid format string
+ *
+ * Checks the string pointed to by @string for starting with a properly
+ * formed #GVariant varargs format string.  If no valid format string is
+ * found then %FALSE is returned.
+ *
+ * If @string does start with a valid format string then %TRUE is
+ * returned.  If @endptr is non-%NULL then it is updated to point to the
+ * first character after the format string.
+ *
+ * If @limit is non-%NULL then @limit (and any charater after it) will
+ * not be accessed and the effect is otherwise equivalent to if the
+ * character at @limit were nul.
+ *
+ * See the section on <link linkend='gvariant-format-strings'>GVariant
+ * Format Strings</link>.
+ *
+ * Since: 2.24
+ */
+gboolean
+g_variant_format_string_scan (const gchar  *string,
+                              const gchar  *limit,
+                              const gchar **endptr)
+{
+#define next_char() (string == limit ? '\0' : *string++)
+#define peek_char() (string == limit ? '\0' : *string)
+  char c;
+
+  switch (next_char())
+    {
+    case 'b': case 'y': case 'n': case 'q': case 'i': case 'u':
+    case 'x': case 't': case 'h': case 'd': case 's': case 'o':
+    case 'g': case 'v': case '*': case '?': case 'r':
+      break;
+
+    case 'm':
+      return g_variant_format_string_scan (string, limit, endptr);
+
+    case 'a':
+    case '@':
+      return g_variant_type_string_scan (string, limit, endptr);
+
+    case '(':
+      while (peek_char() != ')')
+        if (!g_variant_format_string_scan (string, limit, &string))
+          return FALSE;
+
+      next_char(); /* consume ')' */
+      break;
+
+    case '{':
+      c = next_char();
+
+      if (c == '&')
+        {
+          c = next_char ();
+
+          if (c != 's' && c != 'o' && c != 'g')
+            return FALSE;
+        }
+      else
+        {
+          if (c == '@')
+            c = next_char ();
+
+          /* ISO/IEC 9899:1999 (C99) §7.21.5.2:
+           *    The terminating null character is considered to be
+           *    part of the string.
+           */
+          if (c != '\0' && strchr ("bynqiuxthdsog?", c) == NULL)
+            return FALSE;
+        }
+
+      if (!g_variant_format_string_scan (string, limit, &string))
+        return FALSE;
+
+      if (next_char() != '}')
+        return FALSE;
+
+      break;
+
+    case '^':
+      if ((c = next_char()) == 'a')
+        {
+          if ((c = next_char()) == '&')
+            {
+              if ((c = next_char()) == 'a')
+                {
+                  if ((c = next_char()) == 'y')
+                    break;      /* '^a&ay' */
+                }
+
+              else if (c == 's')
+                break;          /* '^a&s' */
+            }
+
+          else if (c == 'a')
+            {
+              if ((c = next_char()) == 'y')
+                break;          /* '^aay' */
+            }
+
+          else if (c == 's')
+            break;              /* '^as' */
+
+          else if (c == 'y')
+            break;              /* '^ay' */
+        }
+      else if (c == '&')
+        {
+          if ((c = next_char()) == 'a')
+            {
+              if ((c = next_char()) == 'y')
+                break;          /* '^&ay' */
+            }
+        }
+
+      return FALSE;
+
+    case '&':
+      c = next_char();
+
+      if (c != 's' && c != 'o' && c != 'g')
+        return FALSE;
+
+      break;
+
+    default:
+      return FALSE;
+    }
+
+  if (endptr != NULL)
+    *endptr = string;
+
+#undef next_char
+#undef peek_char
+
+  return TRUE;
+}
+
+/*< private >
+ * g_variant_format_string_scan_type:
+ * @string: a string that may be prefixed with a format string
+ * @limit: (allow-none) (default NULL): a pointer to the end of @string,
+ *         or %NULL
+ * @endptr: (allow-none) (default NULL): location to store the end pointer,
+ *          or %NULL
+ * @returns: (allow-none): a #GVariantType if there was a valid format string
+ *
+ * If @string starts with a valid format string then this function will
+ * return the type that the format string corresponds to.  Otherwise
+ * this function returns %NULL.
+ *
+ * Use g_variant_type_free() to free the return value when you no longer
+ * need it.
+ *
+ * This function is otherwise exactly like
+ * g_variant_format_string_scan().
+ *
+ * Since: 2.24
+ */
+GVariantType *
+g_variant_format_string_scan_type (const gchar  *string,
+                                   const gchar  *limit,
+                                   const gchar **endptr)
+{
+  const gchar *my_end;
+  gchar *dest;
+  gchar *new;
+
+  if (endptr == NULL)
+    endptr = &my_end;
+
+  if (!g_variant_format_string_scan (string, limit, endptr))
+    return NULL;
+
+  dest = new = g_malloc (*endptr - string + 1);
+  while (string != *endptr)
+    {
+      if (*string != '@' && *string != '&' && *string != '^')
+        *dest++ = *string;
+      string++;
+    }
+  *dest = '\0';
+
+  return (GVariantType *) G_VARIANT_TYPE (new);
+}
+
+static gboolean
+valid_format_string (const gchar *format_string,
+                     gboolean     single,
+                     GVariant    *value)
+{
+  const gchar *endptr;
+  GVariantType *type;
+
+  type = g_variant_format_string_scan_type (format_string, NULL, &endptr);
+
+  if G_UNLIKELY (type == NULL || (single && *endptr != '\0'))
+    {
+      if (single)
+        g_critical ("`%s' is not a valid GVariant format string",
+                    format_string);
+      else
+        g_critical ("`%s' does not have a valid GVariant format "
+                    "string as a prefix", format_string);
+
+      if (type != NULL)
+        g_variant_type_free (type);
+
+      return FALSE;
+    }
+
+  if G_UNLIKELY (value && !g_variant_is_of_type (value, type))
+    {
+      gchar *fragment;
+      gchar *typestr;
+
+      fragment = g_strndup (format_string, endptr - format_string);
+      typestr = g_variant_type_dup_string (type);
+
+      g_critical ("the GVariant format string `%s' has a type of "
+                  "`%s' but the given value has a type of `%s'",
+                  fragment, typestr, g_variant_get_type_string (value));
+
+      g_variant_type_free (type);
+
+      return FALSE;
+    }
+
+  g_variant_type_free (type);
+
+  return TRUE;
+}
+
+/* Variable Arguments {{{1 */
+/* We consider 2 main classes of format strings:
+ *
+ *   - recursive format strings
+ *      these are ones that result in recursion and the collection of
+ *      possibly more than one argument.  Maybe types, tuples,
+ *      dictionary entries.
+ *
+ *   - leaf format string
+ *      these result in the collection of a single argument.
+ *
+ * Leaf format strings are further subdivided into two categories:
+ *
+ *   - single non-null pointer ("nnp")
+ *      these either collect or return a single non-null pointer.
+ *
+ *   - other
+ *      these collect or return something else (bool, number, etc).
+ *
+ * Based on the above, the varargs handling code is split into 4 main parts:
+ *
+ *   - nnp handling code
+ *   - leaf handling code (which may invoke nnp code)
+ *   - generic handling code (may be recursive, may invoke leaf code)
+ *   - user-facing API (which invokes the generic code)
+ *
+ * Each section implements some of the following functions:
+ *
+ *   - skip:
+ *      collect the arguments for the format string as if
+ *      g_variant_new() had been called, but do nothing with them.  used
+ *      for skipping over arguments when constructing a Nothing maybe
+ *      type.
+ *
+ *   - new:
+ *      create a GVariant *
+ *
+ *   - get:
+ *      unpack a GVariant *
+ *
+ *   - free (nnp only):
+ *      free a previously allocated item
+ */
+
+static gboolean
+g_variant_format_string_is_leaf (const gchar *str)
+{
+  return str[0] != 'm' && str[0] != '(' && str[0] != '{';
+}
+
+static gboolean
+g_variant_format_string_is_nnp (const gchar *str)
+{
+  return str[0] == 'a' || str[0] == 's' || str[0] == 'o' || str[0] == 'g' ||
+         str[0] == '^' || str[0] == '@' || str[0] == '*' || str[0] == '?' ||
+         str[0] == 'r' || str[0] == 'v' || str[0] == '&';
+}
+
+/* Single non-null pointer ("nnp") {{{2 */
+static void
+g_variant_valist_free_nnp (const gchar *str,
+                           gpointer     ptr)
+{
+  switch (*str)
+    {
+    case 'a':
+      g_variant_iter_free (ptr);
+      break;
+
+    case '^':
+      if (str[2] != '&')        /* '^as' */
+        g_strfreev (ptr);
+      else                      /* '^a&s' */
+        g_free (ptr);
+      break;
+
+    case 's':
+    case 'o':
+    case 'g':
+      g_free (ptr);
+      break;
+
+    case '@':
+    case '*':
+    case '?':
+    case 'v':
+      g_variant_unref (ptr);
+      break;
+
+    case '&':
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static gchar
+g_variant_scan_convenience (const gchar **str,
+                            gboolean     *constant,
+                            guint        *arrays)
+{
+  *constant = FALSE;
+  *arrays = 0;
+
+  for (;;)
+    {
+      char c = *(*str)++;
+
+      if (c == '&')
+        *constant = TRUE;
+
+      else if (c == 'a')
+        (*arrays)++;
+
+      else
+        return c;
+    }
+}
+
+static GVariant *
+g_variant_valist_new_nnp (const gchar **str,
+                          gpointer      ptr)
+{
+  if (**str == '&')
+    (*str)++;
+
+  switch (*(*str)++)
+    {
+    case 'a':
+      {
+        const GVariantType *type;
+        GVariant *value;
+
+        value = g_variant_builder_end (ptr);
+        type = g_variant_get_type (value);
+
+        if G_UNLIKELY (!g_variant_type_is_array (type))
+          g_error ("g_variant_new: expected array GVariantBuilder but "
+                   "the built value has type `%s'",
+                   g_variant_get_type_string (value));
+
+        type = g_variant_type_element (type);
+
+        if G_UNLIKELY (!g_variant_type_is_subtype_of (type, (GVariantType *) *str))
+          g_error ("g_variant_new: expected GVariantBuilder array element "
+                   "type `%s' but the built value has element type `%s'",
+                   g_variant_type_dup_string ((GVariantType *) *str),
+                   g_variant_get_type_string (value) + 1);
+
+        g_variant_type_string_scan (*str, NULL, str);
+
+        return value;
+      }
+
+    case 's':
+      return g_variant_new_string (ptr);
+
+    case 'o':
+      return g_variant_new_object_path (ptr);
+
+    case 'g':
+      return g_variant_new_signature (ptr);
+
+    case '^':
+      {
+        gboolean constant;
+        guint arrays;
+
+        if (g_variant_scan_convenience (str, &constant, &arrays) == 's')
+          return g_variant_new_strv (ptr, -1);
+
+        if (arrays > 1)
+          return g_variant_new_bytestring_array (ptr, -1);
+
+        return g_variant_new_bytestring (ptr);
+      }
+
+    case '@':
+      if G_UNLIKELY (!g_variant_is_of_type (ptr, (GVariantType *) *str))
+        g_error ("g_variant_new: expected GVariant of type `%s' but "
+                 "received value has type `%s'",
+                 g_variant_type_dup_string ((GVariantType *) *str),
+                 g_variant_get_type_string (ptr));
+
+      g_variant_type_string_scan (*str, NULL, str);
+
+      return ptr;
+
+    case '*':
+      return ptr;
+
+    case '?':
+      if G_UNLIKELY (!g_variant_type_is_basic (g_variant_get_type (ptr)))
+        g_error ("g_variant_new: format string `?' expects basic-typed "
+                 "GVariant, but received value has type `%s'",
+                 g_variant_get_type_string (ptr));
+
+      return ptr;
+
+    case 'r':
+      if G_UNLIKELY (!g_variant_type_is_tuple (g_variant_get_type (ptr)))
+        g_error ("g_variant_new: format string `r` expects tuple-typed "
+                 "GVariant, but received value has type `%s'",
+                 g_variant_get_type_string (ptr));
+
+      return ptr;
+
+    case 'v':
+      return g_variant_new_variant (ptr);
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static gpointer
+g_variant_valist_get_nnp (const gchar **str,
+                          GVariant     *value)
+{
+  switch (*(*str)++)
+    {
+    case 'a':
+      g_variant_type_string_scan (*str, NULL, str);
+      return g_variant_iter_new (value);
+
+    case '&':
+      (*str)++;
+      return (gchar *) g_variant_get_string (value, NULL);
+
+    case 's':
+    case 'o':
+    case 'g':
+      return g_variant_dup_string (value, NULL);
+
+    case '^':
+      {
+        gboolean constant;
+        guint arrays;
+
+        if (g_variant_scan_convenience (str, &constant, &arrays) == 's')
+          {
+            if (constant)
+              return g_variant_get_strv (value, NULL);
+            else
+              return g_variant_dup_strv (value, NULL);
+          }
+
+        else if (arrays > 1)
+          {
+            if (constant)
+              return g_variant_get_bytestring_array (value, NULL);
+            else
+              return g_variant_dup_bytestring_array (value, NULL);
+          }
+
+        else
+          {
+            if (constant)
+              return (gchar *) g_variant_get_bytestring (value);
+            else
+              return g_variant_dup_bytestring (value, NULL);
+          }
+      }
+
+    case '@':
+      g_variant_type_string_scan (*str, NULL, str);
+      /* fall through */
+
+    case '*':
+    case '?':
+    case 'r':
+      return g_variant_ref (value);
+
+    case 'v':
+      return g_variant_get_variant (value);
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+/* Leaves {{{2 */
+static void
+g_variant_valist_skip_leaf (const gchar **str,
+                            va_list      *app)
+{
+  if (g_variant_format_string_is_nnp (*str))
+    {
+      g_variant_format_string_scan (*str, NULL, str);
+      va_arg (*app, gpointer);
+      return;
+    }
+
+  switch (*(*str)++)
+    {
+    case 'b':
+    case 'y':
+    case 'n':
+    case 'q':
+    case 'i':
+    case 'u':
+    case 'h':
+      va_arg (*app, int);
+      return;
+
+    case 'x':
+    case 't':
+      va_arg (*app, guint64);
+      return;
+
+    case 'd':
+      va_arg (*app, gdouble);
+      return;
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static GVariant *
+g_variant_valist_new_leaf (const gchar **str,
+                           va_list      *app)
+{
+  if (g_variant_format_string_is_nnp (*str))
+    return g_variant_valist_new_nnp (str, va_arg (*app, gpointer));
+
+  switch (*(*str)++)
+    {
+    case 'b':
+      return g_variant_new_boolean (va_arg (*app, gboolean));
+
+    case 'y':
+      return g_variant_new_byte (va_arg (*app, guint));
+
+    case 'n':
+      return g_variant_new_int16 (va_arg (*app, gint));
+
+    case 'q':
+      return g_variant_new_uint16 (va_arg (*app, guint));
+
+    case 'i':
+      return g_variant_new_int32 (va_arg (*app, gint));
+
+    case 'u':
+      return g_variant_new_uint32 (va_arg (*app, guint));
+
+    case 'x':
+      return g_variant_new_int64 (va_arg (*app, gint64));
+
+    case 't':
+      return g_variant_new_uint64 (va_arg (*app, guint64));
+
+    case 'h':
+      return g_variant_new_handle (va_arg (*app, gint));
+
+    case 'd':
+      return g_variant_new_double (va_arg (*app, gdouble));
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+/* The code below assumes this */
+G_STATIC_ASSERT (sizeof (gboolean) == sizeof (guint32));
+G_STATIC_ASSERT (sizeof (gdouble) == sizeof (guint64));
+
+static void
+g_variant_valist_get_leaf (const gchar **str,
+                           GVariant     *value,
+                           gboolean      free,
+                           va_list      *app)
+{
+  gpointer ptr = va_arg (*app, gpointer);
+
+  if (ptr == NULL)
+    {
+      g_variant_format_string_scan (*str, NULL, str);
+      return;
+    }
+
+  if (g_variant_format_string_is_nnp (*str))
+    {
+      gpointer *nnp = (gpointer *) ptr;
+
+      if (free && *nnp != NULL)
+        g_variant_valist_free_nnp (*str, *nnp);
+
+      *nnp = NULL;
+
+      if (value != NULL)
+        *nnp = g_variant_valist_get_nnp (str, value);
+      else
+        g_variant_format_string_scan (*str, NULL, str);
+
+      return;
+    }
+
+  if (value != NULL)
+    {
+      switch (*(*str)++)
+        {
+        case 'b':
+          *(gboolean *) ptr = g_variant_get_boolean (value);
+          return;
+
+        case 'y':
+          *(guchar *) ptr = g_variant_get_byte (value);
+          return;
+
+        case 'n':
+          *(gint16 *) ptr = g_variant_get_int16 (value);
+          return;
+
+        case 'q':
+          *(guint16 *) ptr = g_variant_get_uint16 (value);
+          return;
+
+        case 'i':
+          *(gint32 *) ptr = g_variant_get_int32 (value);
+          return;
+
+        case 'u':
+          *(guint32 *) ptr = g_variant_get_uint32 (value);
+          return;
+
+        case 'x':
+          *(gint64 *) ptr = g_variant_get_int64 (value);
+          return;
+
+        case 't':
+          *(guint64 *) ptr = g_variant_get_uint64 (value);
+          return;
+
+        case 'h':
+          *(gint32 *) ptr = g_variant_get_handle (value);
+          return;
+
+        case 'd':
+          *(gdouble *) ptr = g_variant_get_double (value);
+          return;
+        }
+    }
+  else
+    {
+      switch (*(*str)++)
+        {
+        case 'y':
+          *(guchar *) ptr = 0;
+          return;
+
+        case 'n':
+        case 'q':
+          *(guint16 *) ptr = 0;
+          return;
+
+        case 'i':
+        case 'u':
+        case 'h':
+        case 'b':
+          *(guint32 *) ptr = 0;
+          return;
+
+        case 'x':
+        case 't':
+        case 'd':
+          *(guint64 *) ptr = 0;
+          return;
+        }
+    }
+
+  g_assert_not_reached ();
+}
+
+/* Generic (recursive) {{{2 */
+static void
+g_variant_valist_skip (const gchar **str,
+                       va_list      *app)
+{
+  if (g_variant_format_string_is_leaf (*str))
+    g_variant_valist_skip_leaf (str, app);
+
+  else if (**str == 'm') /* maybe */
+    {
+      (*str)++;
+
+      if (!g_variant_format_string_is_nnp (*str))
+        va_arg (*app, gboolean);
+
+      g_variant_valist_skip (str, app);
+    }
+  else /* tuple, dictionary entry */
+    {
+      g_assert (**str == '(' || **str == '{');
+      (*str)++;
+      while (**str != ')' && **str != '}')
+        g_variant_valist_skip (str, app);
+      (*str)++;
+    }
+}
+
+static GVariant *
+g_variant_valist_new (const gchar **str,
+                      va_list      *app)
+{
+  if (g_variant_format_string_is_leaf (*str))
+    return g_variant_valist_new_leaf (str, app);
+
+  if (**str == 'm') /* maybe */
+    {
+      GVariantType *type = NULL;
+      GVariant *value = NULL;
+
+      (*str)++;
+
+      if (g_variant_format_string_is_nnp (*str))
+        {
+          gpointer nnp = va_arg (*app, gpointer);
+
+          if (nnp != NULL)
+            value = g_variant_valist_new_nnp (str, nnp);
+          else
+            type = g_variant_format_string_scan_type (*str, NULL, str);
+        }
+      else
+        {
+          gboolean just = va_arg (*app, gboolean);
+
+          if (just)
+            value = g_variant_valist_new (str, app);
+          else
+            {
+              type = g_variant_format_string_scan_type (*str, NULL, NULL);
+              g_variant_valist_skip (str, app);
+            }
+        }
+
+      value = g_variant_new_maybe (type, value);
+
+      if (type != NULL)
+        g_variant_type_free (type);
+
+      return value;
+    }
+  else /* tuple, dictionary entry */
+    {
+      GVariantBuilder b;
+
+      if (**str == '(')
+        g_variant_builder_init (&b, G_VARIANT_TYPE_TUPLE);
+      else
+        {
+          g_assert (**str == '{');
+          g_variant_builder_init (&b, G_VARIANT_TYPE_DICT_ENTRY);
+        }
+
+      (*str)++; /* '(' */
+      while (**str != ')' && **str != '}')
+        g_variant_builder_add_value (&b, g_variant_valist_new (str, app));
+      (*str)++; /* ')' */
+
+      return g_variant_builder_end (&b);
+    }
+}
+
+static void
+g_variant_valist_get (const gchar **str,
+                      GVariant     *value,
+                      gboolean      free,
+                      va_list      *app)
+{
+  if (g_variant_format_string_is_leaf (*str))
+    g_variant_valist_get_leaf (str, value, free, app);
+
+  else if (**str == 'm')
+    {
+      (*str)++;
+
+      if (value != NULL)
+        value = g_variant_get_maybe (value);
+
+      if (!g_variant_format_string_is_nnp (*str))
+        {
+          gboolean *ptr = va_arg (*app, gboolean *);
+
+          if (ptr != NULL)
+            *ptr = value != NULL;
+        }
+
+      g_variant_valist_get (str, value, free, app);
+
+      if (value != NULL)
+        g_variant_unref (value);
+    }
+
+  else /* tuple, dictionary entry */
+    {
+      gint index = 0;
+
+      g_assert (**str == '(' || **str == '{');
+
+      (*str)++;
+      while (**str != ')' && **str != '}')
+        {
+          if (value != NULL)
+            {
+              GVariant *child = g_variant_get_child_value (value, index++);
+              g_variant_valist_get (str, child, free, app);
+              g_variant_unref (child);
+            }
+          else
+            g_variant_valist_get (str, NULL, free, app);
+        }
+      (*str)++;
+    }
+}
+
+/* User-facing API {{{2 */
+/**
+ * g_variant_new:
+ * @format_string: a #GVariant format string
+ * @...: arguments, as per @format_string
+ * @returns: a new floating #GVariant instance
+ *
+ * Creates a new #GVariant instance.
+ *
+ * Think of this function as an analogue to g_strdup_printf().
+ *
+ * The type of the created instance and the arguments that are
+ * expected by this function are determined by @format_string.  See the
+ * section on <link linkend='gvariant-format-strings'>GVariant Format
+ * Strings</link>.  Please note that the syntax of the format string is
+ * very likely to be extended in the future.
+ *
+ * The first character of the format string must not be '*' '?' '@' or
+ * 'r'; in essence, a new #GVariant must always be constructed by this
+ * function (and not merely passed through it unmodified).
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new (const gchar *format_string,
+               ...)
+{
+  GVariant *value;
+  va_list ap;
+
+  g_return_val_if_fail (valid_format_string (format_string, TRUE, NULL) &&
+                        format_string[0] != '?' && format_string[0] != '@' &&
+                        format_string[0] != '*' && format_string[0] != 'r',
+                        NULL);
+
+  va_start (ap, format_string);
+  value = g_variant_new_va (format_string, NULL, &ap);
+  va_end (ap);
+
+  return value;
+}
+
+/**
+ * g_variant_new_va:
+ * @format_string: a string that is prefixed with a format string
+ * @endptr: (allow-none) (default NULL): location to store the end pointer,
+ *          or %NULL
+ * @app: a pointer to a #va_list
+ * @returns: a new, usually floating, #GVariant
+ *
+ * This function is intended to be used by libraries based on
+ * #GVariant that want to provide g_variant_new()-like functionality
+ * to their users.
+ *
+ * The API is more general than g_variant_new() to allow a wider range
+ * of possible uses.
+ *
+ * @format_string must still point to a valid format string, but it only
+ * needs to be nul-terminated if @endptr is %NULL.  If @endptr is
+ * non-%NULL then it is updated to point to the first character past the
+ * end of the format string.
+ *
+ * @app is a pointer to a #va_list.  The arguments, according to
+ * @format_string, are collected from this #va_list and the list is left
+ * pointing to the argument following the last.
+ *
+ * These two generalisations allow mixing of multiple calls to
+ * g_variant_new_va() and g_variant_get_va() within a single actual
+ * varargs call by the user.
+ *
+ * The return value will be floating if it was a newly created GVariant
+ * instance (for example, if the format string was "(ii)").  In the case
+ * that the format_string was '*', '?', 'r', or a format starting with
+ * '@' then the collected #GVariant pointer will be returned unmodified,
+ * without adding any additional references.
+ *
+ * In order to behave correctly in all cases it is necessary for the
+ * calling function to g_variant_ref_sink() the return result before
+ * returning control to the user that originally provided the pointer.
+ * At this point, the caller will have their own full reference to the
+ * result.  This can also be done by adding the result to a container,
+ * or by passing it to another g_variant_new() call.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_va (const gchar  *format_string,
+                  const gchar **endptr,
+                  va_list      *app)
+{
+  GVariant *value;
+
+  g_return_val_if_fail (valid_format_string (format_string, !endptr, NULL),
+                        NULL);
+  g_return_val_if_fail (app != NULL, NULL);
+
+  value = g_variant_valist_new (&format_string, app);
+
+  if (endptr != NULL)
+    *endptr = format_string;
+
+  return value;
+}
+
+/**
+ * g_variant_get:
+ * @value: a #GVariant instance
+ * @format_string: a #GVariant format string
+ * @...: arguments, as per @format_string
+ *
+ * Deconstructs a #GVariant instance.
+ *
+ * Think of this function as an analogue to scanf().
+ *
+ * The arguments that are expected by this function are entirely
+ * determined by @format_string.  @format_string also restricts the
+ * permissible types of @value.  It is an error to give a value with
+ * an incompatible type.  See the section on <link
+ * linkend='gvariant-format-strings'>GVariant Format Strings</link>.
+ * Please note that the syntax of the format string is very likely to be
+ * extended in the future.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_get (GVariant    *value,
+               const gchar *format_string,
+               ...)
+{
+  va_list ap;
+
+  g_return_if_fail (valid_format_string (format_string, TRUE, value));
+
+  /* if any direct-pointer-access formats are in use, flatten first */
+  if (strchr (format_string, '&'))
+    g_variant_get_data (value);
+
+  va_start (ap, format_string);
+  g_variant_get_va (value, format_string, NULL, &ap);
+  va_end (ap);
+}
+
+/**
+ * g_variant_get_va:
+ * @value: a #GVariant
+ * @format_string: a string that is prefixed with a format string
+ * @endptr: (allow-none) (default NULL): location to store the end pointer,
+ *          or %NULL
+ * @app: a pointer to a #va_list
+ *
+ * This function is intended to be used by libraries based on #GVariant
+ * that want to provide g_variant_get()-like functionality to their
+ * users.
+ *
+ * The API is more general than g_variant_get() to allow a wider range
+ * of possible uses.
+ *
+ * @format_string must still point to a valid format string, but it only
+ * need to be nul-terminated if @endptr is %NULL.  If @endptr is
+ * non-%NULL then it is updated to point to the first character past the
+ * end of the format string.
+ *
+ * @app is a pointer to a #va_list.  The arguments, according to
+ * @format_string, are collected from this #va_list and the list is left
+ * pointing to the argument following the last.
+ *
+ * These two generalisations allow mixing of multiple calls to
+ * g_variant_new_va() and g_variant_get_va() within a single actual
+ * varargs call by the user.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_get_va (GVariant     *value,
+                  const gchar  *format_string,
+                  const gchar **endptr,
+                  va_list      *app)
+{
+  g_return_if_fail (valid_format_string (format_string, !endptr, value));
+  g_return_if_fail (value != NULL);
+  g_return_if_fail (app != NULL);
+
+  /* if any direct-pointer-access formats are in use, flatten first */
+  if (strchr (format_string, '&'))
+    g_variant_get_data (value);
+
+  g_variant_valist_get (&format_string, value, FALSE, app);
+
+  if (endptr != NULL)
+    *endptr = format_string;
+}
+
+/* Varargs-enabled Utility Functions {{{1 */
+
+/**
+ * g_variant_builder_add:
+ * @builder: a #GVariantBuilder
+ * @format_string: a #GVariant varargs format string
+ * @...: arguments, as per @format_string
+ *
+ * Adds to a #GVariantBuilder.
+ *
+ * This call is a convenience wrapper that is exactly equivalent to
+ * calling g_variant_new() followed by g_variant_builder_add_value().
+ *
+ * This function might be used as follows:
+ *
+ * <programlisting>
+ * GVariant *
+ * make_pointless_dictionary (void)
+ * {
+ *   GVariantBuilder *builder;
+ *   int i;
+ *
+ *   builder = g_variant_builder_new (G_VARIANT_TYPE_ARRAY);
+ *   for (i = 0; i < 16; i++)
+ *     {
+ *       gchar buf[3];
+ *
+ *       sprintf (buf, "%d", i);
+ *       g_variant_builder_add (builder, "{is}", i, buf);
+ *     }
+ *
+ *   return g_variant_builder_end (builder);
+ * }
+ * </programlisting>
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_builder_add (GVariantBuilder *builder,
+                       const gchar     *format_string,
+                       ...)
+{
+  GVariant *variant;
+  va_list ap;
+
+  va_start (ap, format_string);
+  variant = g_variant_new_va (format_string, NULL, &ap);
+  va_end (ap);
+
+  g_variant_builder_add_value (builder, variant);
+}
+
+/**
+ * g_variant_get_child:
+ * @value: a container #GVariant
+ * @index_: the index of the child to deconstruct
+ * @format_string: a #GVariant format string
+ * @...: arguments, as per @format_string
+ *
+ * Reads a child item out of a container #GVariant instance and
+ * deconstructs it according to @format_string.  This call is
+ * essentially a combination of g_variant_get_child_value() and
+ * g_variant_get().
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_get_child (GVariant    *value,
+                     gsize        index_,
+                     const gchar *format_string,
+                     ...)
+{
+  GVariant *child;
+  va_list ap;
+
+  child = g_variant_get_child_value (value, index_);
+  g_return_if_fail (valid_format_string (format_string, TRUE, child));
+
+  va_start (ap, format_string);
+  g_variant_get_va (child, format_string, NULL, &ap);
+  va_end (ap);
+
+  g_variant_unref (child);
+}
+
+/**
+ * g_variant_iter_next:
+ * @iter: a #GVariantIter
+ * @format_string: a GVariant format string
+ * @...: the arguments to unpack the value into
+ * @returns: %TRUE if a value was unpacked, or %FALSE if there as no
+ *           value
+ *
+ * Gets the next item in the container and unpacks it into the variable
+ * argument list according to @format_string, returning %TRUE.
+ *
+ * If no more items remain then %FALSE is returned.
+ *
+ * All of the pointers given on the variable arguments list of this
+ * function are assumed to point at uninitialised memory.  It is the
+ * responsibility of the caller to free all of the values returned by
+ * the unpacking process.
+ *
+ * See the section on <link linkend='gvariant-format-strings'>GVariant
+ * Format Strings</link>.
+ *
+ * <example>
+ *  <title>Memory management with g_variant_iter_next()</title>
+ *  <programlisting>
+ *   /<!-- -->* Iterates a dictionary of type 'a{sv}' *<!-- -->/
+ *   void
+ *   iterate_dictionary (GVariant *dictionary)
+ *   {
+ *     GVariantIter iter;
+ *     GVariant *value;
+ *     gchar *key;
+ *
+ *     g_variant_iter_init (&iter, dictionary);
+ *     while (g_variant_iter_next (&iter, "{sv}", &key, &value))
+ *       {
+ *         g_print ("Item '%s' has type '%s'\n", key,
+ *                  g_variant_get_type_string (value));
+ *
+ *         /<!-- -->* must free data for ourselves *<!-- -->/
+ *         g_variant_unref (value);
+ *         g_free (key);
+ *       }
+ *   }
+ *  </programlisting>
+ * </example>
+ *
+ * For a solution that is likely to be more convenient to C programmers
+ * when dealing with loops, see g_variant_iter_loop().
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_iter_next (GVariantIter *iter,
+                     const gchar  *format_string,
+                     ...)
+{
+  GVariant *value;
+
+  value = g_variant_iter_next_value (iter);
+
+  g_return_val_if_fail (valid_format_string (format_string, TRUE, value),
+                        FALSE);
+
+  if (value != NULL)
+    {
+      va_list ap;
+
+      va_start (ap, format_string);
+      g_variant_valist_get (&format_string, value, FALSE, &ap);
+      va_end (ap);
+
+      g_variant_unref (value);
+    }
+
+  return value != NULL;
+}
+
+/**
+ * g_variant_iter_loop:
+ * @iter: a #GVariantIter
+ * @format_string: a GVariant format string
+ * @...: the arguments to unpack the value into
+ * @returns: %TRUE if a value was unpacked, or %FALSE if there as no
+ *           value
+ *
+ * Gets the next item in the container and unpacks it into the variable
+ * argument list according to @format_string, returning %TRUE.
+ *
+ * If no more items remain then %FALSE is returned.
+ *
+ * On the first call to this function, the pointers appearing on the
+ * variable argument list are assumed to point at uninitialised memory.
+ * On the second and later calls, it is assumed that the same pointers
+ * will be given and that they will point to the memory as set by the
+ * previous call to this function.  This allows the previous values to
+ * be freed, as appropriate.
+ *
+ * This function is intended to be used with a while loop as
+ * demonstrated in the following example.  This function can only be
+ * used when iterating over an array.  It is only valid to call this
+ * function with a string constant for the format string and the same
+ * string constant must be used each time.  Mixing calls to this
+ * function and g_variant_iter_next() or g_variant_iter_next_value() on
+ * the same iterator is not recommended.
+ *
+ * See the section on <link linkend='gvariant-format-strings'>GVariant
+ * Format Strings</link>.
+ *
+ * <example>
+ *  <title>Memory management with g_variant_iter_loop()</title>
+ *  <programlisting>
+ *   /<!-- -->* Iterates a dictionary of type 'a{sv}' *<!-- -->/
+ *   void
+ *   iterate_dictionary (GVariant *dictionary)
+ *   {
+ *     GVariantIter iter;
+ *     GVariant *value;
+ *     gchar *key;
+ *
+ *     g_variant_iter_init (&iter, dictionary);
+ *     while (g_variant_iter_loop (&iter, "{sv}", &key, &value))
+ *       {
+ *         g_print ("Item '%s' has type '%s'\n", key,
+ *                  g_variant_get_type_string (value));
+ *
+ *         /<!-- -->* no need to free 'key' and 'value' here *<!-- -->/
+ *       }
+ *   }
+ *  </programlisting>
+ * </example>
+ *
+ * If you want a slightly less magical alternative that requires more
+ * typing, see g_variant_iter_next().
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_iter_loop (GVariantIter *iter,
+                     const gchar  *format_string,
+                     ...)
+{
+  gboolean first_time = GVSI(iter)->loop_format == NULL;
+  GVariant *value;
+  va_list ap;
+
+  g_return_val_if_fail (first_time ||
+                        format_string == GVSI(iter)->loop_format,
+                        FALSE);
+
+  if (first_time)
+    {
+      TYPE_CHECK (GVSI(iter)->value, G_VARIANT_TYPE_ARRAY, FALSE);
+      GVSI(iter)->loop_format = format_string;
+
+      if (strchr (format_string, '&'))
+        g_variant_get_data (GVSI(iter)->value);
+    }
+
+  value = g_variant_iter_next_value (iter);
+
+  g_return_val_if_fail (!first_time ||
+                        valid_format_string (format_string, TRUE, value),
+                        FALSE);
+
+  va_start (ap, format_string);
+  g_variant_valist_get (&format_string, value, !first_time, &ap);
+  va_end (ap);
+
+  if (value != NULL)
+    g_variant_unref (value);
+
+  return value != NULL;
+}
+
+/* Serialised data {{{1 */
+static GVariant *
+g_variant_deep_copy (GVariant *value)
+{
+  switch (g_variant_classify (value))
+    {
+    case G_VARIANT_CLASS_MAYBE:
+    case G_VARIANT_CLASS_ARRAY:
+    case G_VARIANT_CLASS_TUPLE:
+    case G_VARIANT_CLASS_DICT_ENTRY:
+    case G_VARIANT_CLASS_VARIANT:
+      {
+        GVariantBuilder builder;
+        GVariantIter iter;
+        GVariant *child;
+
+        g_variant_builder_init (&builder, g_variant_get_type (value));
+        g_variant_iter_init (&iter, value);
+
+        while ((child = g_variant_iter_next_value (&iter)))
+          {
+            g_variant_builder_add_value (&builder, g_variant_deep_copy (child));
+            g_variant_unref (child);
+          }
+
+        return g_variant_builder_end (&builder);
+      }
+
+    case G_VARIANT_CLASS_BOOLEAN:
+      return g_variant_new_boolean (g_variant_get_boolean (value));
+
+    case G_VARIANT_CLASS_BYTE:
+      return g_variant_new_byte (g_variant_get_byte (value));
+
+    case G_VARIANT_CLASS_INT16:
+      return g_variant_new_int16 (g_variant_get_int16 (value));
+
+    case G_VARIANT_CLASS_UINT16:
+      return g_variant_new_uint16 (g_variant_get_uint16 (value));
+
+    case G_VARIANT_CLASS_INT32:
+      return g_variant_new_int32 (g_variant_get_int32 (value));
+
+    case G_VARIANT_CLASS_UINT32:
+      return g_variant_new_uint32 (g_variant_get_uint32 (value));
+
+    case G_VARIANT_CLASS_INT64:
+      return g_variant_new_int64 (g_variant_get_int64 (value));
+
+    case G_VARIANT_CLASS_UINT64:
+      return g_variant_new_uint64 (g_variant_get_uint64 (value));
+
+    case G_VARIANT_CLASS_HANDLE:
+      return g_variant_new_handle (g_variant_get_handle (value));
+
+    case G_VARIANT_CLASS_DOUBLE:
+      return g_variant_new_double (g_variant_get_double (value));
+
+    case G_VARIANT_CLASS_STRING:
+      return g_variant_new_string (g_variant_get_string (value, NULL));
+
+    case G_VARIANT_CLASS_OBJECT_PATH:
+      return g_variant_new_object_path (g_variant_get_string (value, NULL));
+
+    case G_VARIANT_CLASS_SIGNATURE:
+      return g_variant_new_signature (g_variant_get_string (value, NULL));
+    }
+
+  g_assert_not_reached ();
+}
+
+/**
+ * g_variant_get_normal_form:
+ * @value: a #GVariant
+ * @returns: a trusted #GVariant
+ *
+ * Gets a #GVariant instance that has the same value as @value and is
+ * trusted to be in normal form.
+ *
+ * If @value is already trusted to be in normal form then a new
+ * reference to @value is returned.
+ *
+ * If @value is not already trusted, then it is scanned to check if it
+ * is in normal form.  If it is found to be in normal form then it is
+ * marked as trusted and a new reference to it is returned.
+ *
+ * If @value is found not to be in normal form then a new trusted
+ * #GVariant is created with the same value as @value.
+ *
+ * It makes sense to call this function if you've received #GVariant
+ * data from untrusted sources and you want to ensure your serialised
+ * output is definitely in normal form.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_get_normal_form (GVariant *value)
+{
+  GVariant *trusted;
+
+  if (g_variant_is_normal_form (value))
+    return g_variant_ref (value);
+
+  trusted = g_variant_deep_copy (value);
+  g_assert (g_variant_is_trusted (trusted));
+
+  return g_variant_ref_sink (trusted);
+}
+
+/**
+ * g_variant_byteswap:
+ * @value: a #GVariant
+ * @returns: the byteswapped form of @value
+ *
+ * Performs a byteswapping operation on the contents of @value.  The
+ * result is that all multi-byte numeric data contained in @value is
+ * byteswapped.  That includes 16, 32, and 64bit signed and unsigned
+ * integers as well as file handles and double precision floating point
+ * values.
+ *
+ * This function is an identity mapping on any value that does not
+ * contain multi-byte numeric data.  That include strings, booleans,
+ * bytes and containers containing only these things (recursively).
+ *
+ * The returned value is always in normal form and is marked as trusted.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_byteswap (GVariant *value)
+{
+  GVariantTypeInfo *type_info;
+  guint alignment;
+  GVariant *new;
+
+  type_info = g_variant_get_type_info (value);
+
+  g_variant_type_info_query (type_info, &alignment, NULL);
+
+  if (alignment)
+    /* (potentially) contains multi-byte numeric data */
+    {
+      GVariantSerialised serialised;
+      GVariant *trusted;
+      GBuffer *buffer;
+
+      trusted = g_variant_get_normal_form (value);
+      serialised.type_info = g_variant_get_type_info (trusted);
+      serialised.size = g_variant_get_size (trusted);
+      serialised.data = g_malloc (serialised.size);
+      g_variant_store (trusted, serialised.data);
+      g_variant_unref (trusted);
+
+      g_variant_serialised_byteswap (serialised);
+
+      buffer = g_buffer_new_take_data (serialised.data, serialised.size);
+      new = g_variant_new_from_buffer (g_variant_get_type (value), buffer, TRUE);
+      g_buffer_unref (buffer);
+    }
+  else
+    /* contains no multi-byte data */
+    new = value;
+
+  return g_variant_ref_sink (new);
+}
+
+/**
+ * g_variant_new_from_data:
+ * @type: a definite #GVariantType
+ * @data: the serialised data
+ * @size: the size of @data
+ * @trusted: %TRUE if @data is definitely in normal form
+ * @notify: function to call when @data is no longer needed
+ * @user_data: data for @notify
+ * @returns: a new floating #GVariant of type @type
+ *
+ * Creates a new #GVariant instance from serialised data.
+ *
+ * @type is the type of #GVariant instance that will be constructed.
+ * The interpretation of @data depends on knowing the type.
+ *
+ * @data is not modified by this function and must remain valid with an
+ * unchanging value until such a time as @notify is called with
+ * @user_data.  If the contents of @data change before that time then
+ * the result is undefined.
+ *
+ * If @data is trusted to be serialised data in normal form then
+ * @trusted should be %TRUE.  This applies to serialised data created
+ * within this process or read from a trusted location on the disk (such
+ * as a file installed in /usr/lib alongside your application).  You
+ * should set trusted to %FALSE if @data is read from the network, a
+ * file in the user's home directory, etc.
+ *
+ * @notify will be called with @user_data when @data is no longer
+ * needed.  The exact time of this call is unspecified and might even be
+ * before this function returns.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_new_from_data (const GVariantType *type,
+                         gconstpointer       data,
+                         gsize               size,
+                         gboolean            trusted,
+                         GDestroyNotify      notify,
+                         gpointer            user_data)
+{
+  GVariant *value;
+  GBuffer *buffer;
+
+  g_return_val_if_fail (g_variant_type_is_definite (type), NULL);
+  g_return_val_if_fail (data != NULL || size == 0, NULL);
+
+  if (notify)
+    buffer = g_buffer_new_from_pointer (data, size, notify, user_data);
+  else
+    buffer = g_buffer_new_from_static_data (data, size);
+
+  value = g_variant_new_from_buffer (type, buffer, trusted);
+  g_buffer_unref (buffer);
+
+  return value;
+}
+
+/* Epilogue {{{1 */
+/* vim:set foldmethod=marker: */