glib inlined into SameTime

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

1 files changed, 974 insertions, 0 deletions

diff --git a/protocols/Sametime/src/glib/gvariant-core.c b/protocols/Sametime/src/glib/gvariant-core.c
new file mode 100644
index 0000000000..6f019307a4
--- /dev/null
+++ b/protocols/Sametime/src/glib/gvariant-core.c
@@ -0,0 +1,974 @@
+/*
+ * 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 License, 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.
+ */
+
+#include <glib/gvariant-core.h>
+
+#include <glib/gvariant-serialiser.h>
+#include <glib/gtestutils.h>
+#include <glib/gbitlock.h>
+#include <glib/gatomic.h>
+#include <glib/gbuffer.h>
+#include <glib/gslice.h>
+#include <glib/gmem.h>
+#include <string.h>
+
+
+/*
+ * This file includes the structure definition for GVariant and a small
+ * set of functions that are allowed to access the structure directly.
+ *
+ * This minimises the amount of code that can possibly touch a GVariant
+ * structure directly to a few simple fundamental operations.  These few
+ * operations are written to be completely threadsafe with respect to
+ * all possible outside access.  This means that we only need to be
+ * concerned about thread safety issues in this one small file.
+ *
+ * Most GVariant API functions are in gvariant.c.
+ */
+
+/**
+ * GVariant:
+ *
+ * #GVariant is an opaque data structure and can only be accessed
+ * using the following functions.
+ *
+ * Since: 2.24
+ **/
+struct _GVariant
+/* see below for field member documentation */
+{
+  GVariantTypeInfo *type_info;
+  gsize size;
+
+  union
+  {
+    struct
+    {
+      GBuffer *buffer;
+      gconstpointer data;
+    } serialised;
+
+    struct
+    {
+      GVariant **children;
+      gsize n_children;
+    } tree;
+  } contents;
+
+  gint state;
+  gint ref_count;
+};
+
+/* struct GVariant:
+ *
+ * There are two primary forms of GVariant instances: "serialised form"
+ * and "tree form".
+ *
+ * "serialised form": A serialised GVariant instance stores its value in
+ *                    the GVariant serialisation format.  All
+ *                    basic-typed instances (ie: non-containers) are in
+ *                    serialised format, as are some containers.
+ *
+ * "tree form": Some containers are in "tree form".  In this case,
+ *              instead of containing the serialised data for the
+ *              container, the instance contains an array of pointers to
+ *              the child values of the container (thus forming a tree).
+ *
+ * It is possible for an instance to transition from tree form to
+ * serialised form.  This happens, implicitly, if the serialised data is
+ * requested (eg: via g_variant_get_data()).  Serialised form instances
+ * never transition into tree form.
+ *
+ *
+ * The fields of the structure are documented here:
+ *
+ * type_info: this is a reference to a GVariantTypeInfo describing the
+ *            type of the instance.  When the instance is freed, this
+ *            reference must be released with g_variant_type_info_unref().
+ *
+ *            The type_info field never changes during the life of the
+ *            instance, so it can be accessed without a lock.
+ *
+ * size: this is the size of the serialised form for the instance, if it
+ *       is known.  If the instance is in serialised form then it is, by
+ *       definition, known.  If the instance is in tree form then it may
+ *       be unknown (in which case it is -1).  It is possible for the
+ *       size to be known when in tree form if, for example, the user
+ *       has called g_variant_get_size() without calling
+ *       g_variant_get_data().  Additionally, even when the user calls
+ *       g_variant_get_data() the size of the data must first be
+ *       determined so that a large enough buffer can be allocated for
+ *       the data.
+ *
+ *       Once the size is known, it can never become unknown again.
+ *       g_variant_ensure_size() is used to ensure that the size is in
+ *       the known state -- it calculates the size if needed.  After
+ *       that, the size field can be accessed without a lock.
+ *
+ * contents: a union containing either the information associated with
+ *           holding a value in serialised form or holding a value in
+ *           tree form.
+ *
+ *   .serialised: Only valid when the instance is in serialised form.
+ *
+ *                Since an instance can never transition away from
+ *                serialised form, once these fields are set, they will
+ *                never be changed.  It is therefore valid to access
+ *                them without holding a lock.
+ *
+ *     .buffer: the #GBuffer that contains the memory pointed to by
+ *              .data, or %NULL if .data is %NULL.  In the event that
+ *              the instance was deserialised from another instance,
+ *              then the buffer will be shared by both of them.  When
+ *              the instance is freed, this reference must be released
+ *              with g_buffer_unref().
+ *
+ *     .data: the serialised data (of size 'size') of the instance.
+ *            This pointer should not be freed or modified in any way.
+ *            #GBuffer is responsible for memory management.
+ *
+ *            This pointer may be %NULL in two cases:
+ *
+ *              - if the serialised size of the instance is 0
+ *
+ *              - if the instance is of a fixed-sized type and was
+ *                deserialised out of a corrupted container such that
+ *                the container contains too few bytes to point to the
+ *                entire proper fixed-size of this instance.  In this
+ *                case, 'size' will still be equal to the proper fixed
+ *                size, but this pointer will be %NULL.  This is exactly
+ *                the reason that g_variant_get_data() sometimes returns
+ *                %NULL.  For all other calls, the effect should be as
+ *                if .data pointed to the appropriate number of nul
+ *                bytes.
+ *
+ *   .tree: Only valid when the instance is in tree form.
+ *
+ *          Note that accesses from other threads could result in
+ *          conversion of the instance from tree form to serialised form
+ *          at any time.  For this reason, the instance lock must always
+ *          be held while performing any operations on 'contents.tree'.
+ *
+ *     .children: the array of the child instances of this instance.
+ *                When the instance is freed (or converted to serialised
+ *                form) then each child must have g_variant_unref()
+ *                called on it and the array must be freed using
+ *                g_free().
+ *
+ *     .n_children: the number of items in the .children array.
+ *
+ * state: a bitfield describing the state of the instance.  It is a
+ *        bitwise-or of the following STATE_* constants:
+ *
+ *    STATE_LOCKED: the instance lock is held.  This is the bit used by
+ *                  g_bit_lock().
+ *
+ *    STATE_SERIALISED: the instance is in serialised form.  If this
+ *                      flag is not set then the instance is in tree
+ *                      form.
+ *
+ *    STATE_TRUSTED: for serialised form instances, this means that the
+ *                   serialised data is known to be in normal form (ie:
+ *                   not corrupted).
+ *
+ *                   For tree form instances, this means that all of the
+ *                   child instances in the contents.tree.children array
+ *                   are trusted.  This means that if the container is
+ *                   serialised then the resulting data will be in
+ *                   normal form.
+ *
+ *                   If this flag is unset it does not imply that the
+ *                   data is corrupted.  It merely means that we're not
+ *                   sure that it's valid.  See g_variant_is_trusted().
+ *
+ *    STATE_FLOATING: if this flag is set then the object has a floating
+ *                    reference.  See g_variant_ref_sink().
+ *
+ * ref_count: the reference count of the instance
+ */
+#define STATE_LOCKED     1
+#define STATE_SERIALISED 2
+#define STATE_TRUSTED    4
+#define STATE_FLOATING   8
+
+/* -- private -- */
+/* < private >
+ * g_variant_lock:
+ * @value: a #GVariant
+ *
+ * Locks @value for performing sensitive operations.
+ */
+static void
+g_variant_lock (GVariant *value)
+{
+  g_bit_lock (&value->state, 0);
+}
+
+/* < private >
+ * g_variant_unlock:
+ * @value: a #GVariant
+ *
+ * Unlocks @value after performing sensitive operations.
+ */
+static void
+g_variant_unlock (GVariant *value)
+{
+  g_bit_unlock (&value->state, 0);
+}
+
+/* < private >
+ * g_variant_release_children:
+ * @value: a #GVariant
+ *
+ * Releases the reference held on each child in the 'children' array of
+ * @value and frees the array itself.  @value must be in tree form.
+ *
+ * This is done when freeing a tree-form instance or converting it to
+ * serialised form.
+ *
+ * The current thread must hold the lock on @value.
+ */
+static void
+g_variant_release_children (GVariant *value)
+{
+  gsize i;
+
+  g_assert (value->state & STATE_LOCKED);
+  g_assert (~value->state & STATE_SERIALISED);
+
+  for (i = 0; i < value->contents.tree.n_children; i++)
+    g_variant_unref (value->contents.tree.children[i]);
+
+  g_free (value->contents.tree.children);
+}
+
+/* This begins the main body of the recursive serialiser.
+ *
+ * There are 3 functions here that work as a team with the serialiser to
+ * get things done.  g_variant_store() has a trivial role, but as a
+ * public API function, it has its definition elsewhere.
+ *
+ * Note that "serialisation" of an instance does not mean that the
+ * instance is converted to serialised form -- it means that the
+ * serialised form of an instance is written to an external buffer.
+ * g_variant_ensure_serialised() (which is not part of this set of
+ * functions) is the function that is responsible for converting an
+ * instance to serialised form.
+ *
+ * We are only concerned here with container types since non-container
+ * instances are always in serialised form.  For these instances,
+ * storing their serialised form merely involves a memcpy().
+ *
+ * Serialisation is a two-step process.  First, the size of the
+ * serialised data must be calculated so that an appropriately-sized
+ * buffer can be allocated.  Second, the data is written into the
+ * buffer.
+ *
+ * Determining the size:
+ *   The process of determining the size is triggered by a call to
+ *   g_variant_ensure_size() on a container.  This invokes the
+ *   serialiser code to determine the size.  The serialiser is passed
+ *   g_variant_fill_gvs() as a callback.
+ *
+ *   g_variant_fill_gvs() is called by the serialiser on each child of
+ *   the container which, in turn, calls g_variant_ensure_size() on
+ *   itself and fills in the result of its own size calculation.
+ *
+ *   The serialiser uses the size information from the children to
+ *   calculate the size needed for the entire container.
+ *
+ * Writing the data:
+ *   After the buffer has been allocated, g_variant_serialise() is
+ *   called on the container.  This invokes the serialiser code to write
+ *   the bytes to the container.  The serialiser is, again, passed
+ *   g_variant_fill_gvs() as a callback.
+ *
+ *   This time, when g_variant_fill_gvs() is called for each child, the
+ *   child is given a pointer to a sub-region of the allocated buffer
+ *   where it should write its data.  This is done by calling
+ *   g_variant_store().  In the event that the instance is in serialised
+ *   form this means a memcpy() of the serialised data into the
+ *   allocated buffer.  In the event that the instance is in tree form
+ *   this means a recursive call back into g_variant_serialise().
+ *
+ *
+ * The forward declaration here allows corecursion via callback:
+ */
+static void g_variant_fill_gvs (GVariantSerialised *, gpointer);
+
+/* < private >
+ * g_variant_ensure_size:
+ * @value: a #GVariant
+ *
+ * Ensures that the ->size field of @value is filled in properly.  This
+ * must be done as a precursor to any serialisation of the value in
+ * order to know how large of a buffer is needed to store the data.
+ *
+ * The current thread must hold the lock on @value.
+ */
+static void
+g_variant_ensure_size (GVariant *value)
+{
+  g_assert (value->state & STATE_LOCKED);
+
+  if (value->size == (gssize) -1)
+    {
+      gpointer *children;
+      gsize n_children;
+
+      children = (gpointer *) value->contents.tree.children;
+      n_children = value->contents.tree.n_children;
+      value->size = g_variant_serialiser_needed_size (value->type_info,
+                                                      g_variant_fill_gvs,
+                                                      children, n_children);
+    }
+}
+
+/* < private >
+ * g_variant_serialise:
+ * @value: a #GVariant
+ * @data: an appropriately-sized buffer
+ *
+ * Serialises @value into @data.  @value must be in tree form.
+ *
+ * No change is made to @value.
+ *
+ * The current thread must hold the lock on @value.
+ */
+static void
+g_variant_serialise (GVariant *value,
+                     gpointer  data)
+{
+  GVariantSerialised serialised = { 0, };
+  gpointer *children;
+  gsize n_children;
+
+  g_assert (~value->state & STATE_SERIALISED);
+  g_assert (value->state & STATE_LOCKED);
+
+  serialised.type_info = value->type_info;
+  serialised.size = value->size;
+  serialised.data = data;
+
+  children = (gpointer *) value->contents.tree.children;
+  n_children = value->contents.tree.n_children;
+
+  g_variant_serialiser_serialise (serialised, g_variant_fill_gvs,
+                                  children, n_children);
+}
+
+/* < private >
+ * g_variant_fill_gvs:
+ * @serialised: a pointer to a #GVariantSerialised
+ * @data: a #GVariant instance
+ *
+ * This is the callback that is passed by a tree-form container instance
+ * to the serialiser.  This callback gets called on each child of the
+ * container.  Each child is responsible for performing the following
+ * actions:
+ *
+ *  - reporting its type
+ *
+ *  - reporting its serialised size (requires knowing the size first)
+ *
+ *  - possibly storing its serialised form into the provided buffer
+ */
+static void
+g_variant_fill_gvs (GVariantSerialised *serialised,
+                    gpointer            data)
+{
+  GVariant *value = data;
+
+  g_variant_lock (value);
+  g_variant_ensure_size (value);
+  g_variant_unlock (value);
+
+  if (serialised->type_info == NULL)
+    serialised->type_info = value->type_info;
+  g_assert (serialised->type_info == value->type_info);
+
+  if (serialised->size == 0)
+    serialised->size = value->size;
+  g_assert (serialised->size == value->size);
+
+  if (serialised->data)
+    /* g_variant_store() is a public API, so it
+     * it will reacquire the lock if it needs to.
+     */
+    g_variant_store (value, serialised->data);
+}
+
+/* this ends the main body of the recursive serialiser */
+
+/* < private >
+ * g_variant_ensure_serialised:
+ * @value: a #GVariant
+ *
+ * Ensures that @value is in serialised form.
+ *
+ * If @value is in tree form then this function ensures that the
+ * serialised size is known and then allocates a buffer of that size and
+ * serialises the instance into the buffer.  The 'children' array is
+ * then released and the instance is set to serialised form based on the
+ * contents of the buffer.
+ *
+ * The current thread must hold the lock on @value.
+ */
+static void
+g_variant_ensure_serialised (GVariant *value)
+{
+  g_assert (value->state & STATE_LOCKED);
+
+  if (~value->state & STATE_SERIALISED)
+    {
+      GBuffer *buffer;
+      gpointer data;
+
+      g_variant_ensure_size (value);
+      data = g_malloc (value->size);
+      g_variant_serialise (value, data);
+
+      g_variant_release_children (value);
+
+      buffer = g_buffer_new_take_data (data, value->size);
+      value->contents.serialised.data = buffer->data;
+      value->contents.serialised.buffer = buffer;
+      value->state |= STATE_SERIALISED;
+    }
+}
+
+/* < private >
+ * g_variant_alloc:
+ * @type: the type of the new instance
+ * @serialised: if the instance will be in serialised form
+ * @trusted: if the instance will be trusted
+ * @returns: a new #GVariant with a floating reference
+ *
+ * Allocates a #GVariant instance and does some common work (such as
+ * looking up and filling in the type info), setting the state field,
+ * and setting the ref_count to 1.
+ */
+static GVariant *
+g_variant_alloc (const GVariantType *type,
+                 gboolean            serialised,
+                 gboolean            trusted)
+{
+  GVariant *value;
+
+  value = g_slice_new (GVariant);
+  value->type_info = g_variant_type_info_get (type);
+  value->state = (serialised ? STATE_SERIALISED : 0) |
+                 (trusted ? STATE_TRUSTED : 0) |
+                 STATE_FLOATING;
+  value->size = (gssize) -1;
+  value->ref_count = 1;
+
+  return value;
+}
+
+/* -- internal -- */
+/* < internal >
+ * g_variant_new_from_buffer:
+ * @type: a #GVariantType
+ * @buffer: a #GBuffer
+ * @trusted: if the contents of @buffer are trusted
+ * @returns: a new #GVariant with a floating reference
+ *
+ * Constructs a new serialised-mode #GVariant instance.  This is the
+ * inner interface for creation of new serialised values that gets
+ * called from various functions in gvariant.c.
+ *
+ * A reference is taken on @buffer.
+ */
+GVariant *
+g_variant_new_from_buffer (const GVariantType *type,
+                           GBuffer            *buffer,
+                           gboolean            trusted)
+{
+  GVariant *value;
+  guint alignment;
+  gsize size;
+
+  value = g_variant_alloc (type, TRUE, trusted);
+
+  value->contents.serialised.buffer = g_buffer_ref (buffer);
+
+  g_variant_type_info_query (value->type_info,
+                             &alignment, &size);
+
+  if (size && buffer->size != size)
+    {
+      /* Creating a fixed-sized GVariant with a buffer of the wrong
+       * size.
+       *
+       * We should do the equivalent of pulling a fixed-sized child out
+       * of a brozen container (ie: data is NULL size is equal to the correct
+       * fixed size).
+       */
+      value->contents.serialised.data = NULL;
+      value->size = size;
+    }
+  else
+    {
+      value->contents.serialised.data = buffer->data;
+      value->size = buffer->size;
+    }
+
+  return value;
+}
+
+/* < internal >
+ * g_variant_new_from_children:
+ * @type: a #GVariantType
+ * @children: an array of #GVariant pointers.  Consumed.
+ * @n_children: the length of @children
+ * @trusted: %TRUE if every child in @children in trusted
+ * @returns: a new #GVariant with a floating reference
+ *
+ * Constructs a new tree-mode #GVariant instance.  This is the inner
+ * interface for creation of new serialised values that gets called from
+ * various functions in gvariant.c.
+ *
+ * @children is consumed by this function.  g_free() will be called on
+ * it some time later.
+ */
+GVariant *
+g_variant_new_from_children (const GVariantType  *type,
+                             GVariant           **children,
+                             gsize                n_children,
+                             gboolean             trusted)
+{
+  GVariant *value;
+
+  value = g_variant_alloc (type, FALSE, trusted);
+  value->contents.tree.children = children;
+  value->contents.tree.n_children = n_children;
+
+  return value;
+}
+
+/* < internal >
+ * g_variant_get_type_info:
+ * @value: a #GVariant
+ * @returns: the #GVariantTypeInfo for @value
+ *
+ * Returns the #GVariantTypeInfo corresponding to the type of @value.  A
+ * reference is not added, so the return value is only good for the
+ * duration of the life of @value.
+ */
+GVariantTypeInfo *
+g_variant_get_type_info (GVariant *value)
+{
+  return value->type_info;
+}
+
+/* < internal >
+ * g_variant_is_trusted:
+ * @value: a #GVariant
+ * @returns: if @value is trusted
+ *
+ * Determines if @value is trusted by #GVariant to contain only
+ * fully-valid data.  All values constructed solely via #GVariant APIs
+ * are trusted, but values containing data read in from other sources
+ * are usually not trusted.
+ *
+ * The main advantage of trusted data is that certain checks can be
+ * skipped.  For example, we don't need to check that a string is
+ * properly nul-terminated or that an object path is actually a
+ * properly-formatted object path.
+ */
+gboolean
+g_variant_is_trusted (GVariant *value)
+{
+  return (value->state & STATE_TRUSTED) != 0;
+}
+
+/* -- public -- */
+
+/**
+ * g_variant_unref:
+ * @value: a #GVariant
+ *
+ * Decreases the reference count of @value.  When its reference count
+ * drops to 0, the memory used by the variant is freed.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_unref (GVariant *value)
+{
+  if (g_atomic_int_dec_and_test (&value->ref_count))
+    {
+      if G_UNLIKELY (value->state & STATE_LOCKED)
+        g_critical ("attempting to free a locked GVariant instance.  "
+                    "This should never happen.");
+
+      value->state |= STATE_LOCKED;
+
+      g_variant_type_info_unref (value->type_info);
+
+      if (value->state & STATE_SERIALISED)
+        g_buffer_unref (value->contents.serialised.buffer);
+      else
+        g_variant_release_children (value);
+
+      g_slice_free (GVariant, value);
+    }
+}
+
+/**
+ * g_variant_ref:
+ * @value: a #GVariant
+ * @returns: the same @value
+ *
+ * Increases the reference count of @value.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_ref (GVariant *value)
+{
+  g_atomic_int_inc (&value->ref_count);
+
+  return value;
+}
+
+/**
+ * g_variant_ref_sink:
+ * @value: a #GVariant
+ * @returns: the same @value
+ *
+ * #GVariant uses a floating reference count system.  All functions with
+ * names starting with <literal>g_variant_new_</literal> return floating
+ * references.
+ *
+ * Calling g_variant_ref_sink() on a #GVariant with a floating reference
+ * will convert the floating reference into a full reference.  Calling
+ * g_variant_ref_sink() on a non-floating #GVariant results in an
+ * additional normal reference being added.
+ *
+ * In other words, if the @value is floating, then this call "assumes
+ * ownership" of the floating reference, converting it to a normal
+ * reference.  If the @value is not floating, then this call adds a
+ * new normal reference increasing the reference count by one.
+ *
+ * All calls that result in a #GVariant instance being inserted into a
+ * container will call g_variant_ref_sink() on the instance.  This means
+ * that if the value was just created (and has only its floating
+ * reference) then the container will assume sole ownership of the value
+ * at that point and the caller will not need to unreference it.  This
+ * makes certain common styles of programming much easier while still
+ * maintaining normal refcounting semantics in situations where values
+ * are not floating.
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_ref_sink (GVariant *value)
+{
+  g_variant_lock (value);
+
+  if (~value->state & STATE_FLOATING)
+    g_variant_ref (value);
+  else
+    value->state &= ~STATE_FLOATING;
+
+  g_variant_unlock (value);
+
+  return value;
+}
+
+/**
+ * g_variant_is_floating:
+ * @value: a #GVariant
+ * @returns: whether @value is floating
+ *
+ * Checks whether @value has a floating reference count.
+ *
+ * This function should only ever be used to assert that a given variant
+ * is or is not floating, or for debug purposes. To acquire a reference
+ * to a variant that might be floating, always use g_variant_ref_sink().
+ *
+ * See g_variant_ref_sink() for more information about floating reference
+ * counts.
+ *
+ * Since: 2.26
+ **/
+gboolean
+g_variant_is_floating (GVariant *value)
+{
+  g_return_val_if_fail (value != NULL, FALSE);
+
+  return (value->state & STATE_FLOATING) != 0;
+}
+
+/**
+ * g_variant_get_size:
+ * @value: a #GVariant instance
+ * @returns: the serialised size of @value
+ *
+ * Determines the number of bytes that would be required to store @value
+ * with g_variant_store().
+ *
+ * If @value has a fixed-sized type then this function always returned
+ * that fixed size.
+ *
+ * In the case that @value is already in serialised form or the size has
+ * already been calculated (ie: this function has been called before)
+ * then this function is O(1).  Otherwise, the size is calculated, an
+ * operation which is approximately O(n) in the number of values
+ * involved.
+ *
+ * Since: 2.24
+ **/
+gsize
+g_variant_get_size (GVariant *value)
+{
+  g_variant_lock (value);
+  g_variant_ensure_size (value);
+  g_variant_unlock (value);
+
+  return value->size;
+}
+
+/**
+ * g_variant_get_data:
+ * @value: a #GVariant instance
+ * @returns: the serialised form of @value, or %NULL
+ *
+ * Returns a pointer to the serialised form of a #GVariant instance.
+ * The returned data may not be in fully-normalised form if read from an
+ * untrusted source.  The returned data must not be freed; it remains
+ * valid for as long as @value exists.
+ *
+ * If @value is a fixed-sized value that was deserialised from a
+ * corrupted serialised container then %NULL may be returned.  In this
+ * case, the proper thing to do is typically to use the appropriate
+ * number of nul bytes in place of @value.  If @value is not fixed-sized
+ * then %NULL is never returned.
+ *
+ * In the case that @value is already in serialised form, this function
+ * is O(1).  If the value is not already in serialised form,
+ * serialisation occurs implicitly and is approximately O(n) in the size
+ * of the result.
+ *
+ * Since: 2.24
+ **/
+gconstpointer
+g_variant_get_data (GVariant *value)
+{
+  g_variant_lock (value);
+  g_variant_ensure_serialised (value);
+  g_variant_unlock (value);
+
+  return value->contents.serialised.data;
+}
+
+/**
+ * g_variant_n_children:
+ * @value: a container #GVariant
+ * @returns: the number of children in the container
+ *
+ * Determines the number of children in a container #GVariant instance.
+ * This includes variants, maybes, arrays, tuples and dictionary
+ * entries.  It is an error to call this function on any other type of
+ * #GVariant.
+ *
+ * For variants, the return value is always 1.  For values with maybe
+ * types, it is always zero or one.  For arrays, it is the length of the
+ * array.  For tuples it is the number of tuple items (which depends
+ * only on the type).  For dictionary entries, it is always 2
+ *
+ * This function is O(1).
+ *
+ * Since: 2.24
+ **/
+gsize
+g_variant_n_children (GVariant *value)
+{
+  gsize n_children;
+
+  g_variant_lock (value);
+
+  if (value->state & STATE_SERIALISED)
+    {
+      GVariantSerialised serialised = {
+        value->type_info,
+        (gpointer) value->contents.serialised.data,
+        value->size
+      };
+
+      n_children = g_variant_serialised_n_children (serialised);
+    }
+  else
+    n_children = value->contents.tree.n_children;
+
+  g_variant_unlock (value);
+
+  return n_children;
+}
+
+/**
+ * g_variant_get_child_value:
+ * @value: a container #GVariant
+ * @index_: the index of the child to fetch
+ * @returns: the child at the specified index
+ *
+ * Reads a child item out of a container #GVariant instance.  This
+ * includes variants, maybes, arrays, tuples and dictionary
+ * entries.  It is an error to call this function on any other type of
+ * #GVariant.
+ *
+ * It is an error if @index_ is greater than the number of child items
+ * in the container.  See g_variant_n_children().
+ *
+ * This function is O(1).
+ *
+ * Since: 2.24
+ **/
+GVariant *
+g_variant_get_child_value (GVariant *value,
+                           gsize     index_)
+{
+  GVariant *child = NULL;
+
+  g_variant_lock (value);
+
+  if (value->state & STATE_SERIALISED)
+    {
+      GVariantSerialised serialised = {
+        value->type_info,
+        (gpointer) value->contents.serialised.data,
+        value->size
+      };
+      GVariantSerialised s_child;
+
+      /* get the serialiser to extract the serialised data for the child
+       * from the serialised data for the container
+       */
+      s_child = g_variant_serialised_get_child (serialised, index_);
+
+      /* create a new serialised instance out of it */
+      child = g_slice_new (GVariant);
+      child->type_info = s_child.type_info;
+      child->state = (value->state & STATE_TRUSTED) |
+                     STATE_SERIALISED;
+      child->size = s_child.size;
+      child->ref_count = 1;
+      child->contents.serialised.buffer =
+        g_buffer_ref (value->contents.serialised.buffer);
+      child->contents.serialised.data = s_child.data;
+     }
+  else
+    child = g_variant_ref (value->contents.tree.children[index_]);
+
+  g_variant_unlock (value);
+
+  return child;
+}
+
+/**
+ * g_variant_store:
+ * @value: the #GVariant to store
+ * @data: the location to store the serialised data at
+ *
+ * Stores the serialised form of @value at @data.  @data should be
+ * large enough.  See g_variant_get_size().
+ *
+ * The stored data is in machine native byte order but may not be in
+ * fully-normalised form if read from an untrusted source.  See
+ * g_variant_normalise() for a solution.
+ *
+ * This function is approximately O(n) in the size of @data.
+ *
+ * Since: 2.24
+ **/
+void
+g_variant_store (GVariant *value,
+                 gpointer  data)
+{
+  g_variant_lock (value);
+
+  if (value->state & STATE_SERIALISED)
+    {
+      if (value->contents.serialised.data != NULL)
+        memcpy (data, value->contents.serialised.data, value->size);
+      else
+        memset (data, 0, value->size);
+    }
+  else
+    g_variant_serialise (value, data);
+
+  g_variant_unlock (value);
+}
+
+/**
+ * g_variant_is_normal_form:
+ * @value: a #GVariant instance
+ * @returns: %TRUE if @value is in normal form
+ *
+ * Checks if @value is in normal form.
+ *
+ * The main reason to do this is to detect if a given chunk of
+ * serialised data is in normal form: load the data into a #GVariant
+ * using g_variant_create_from_data() and then use this function to
+ * check.
+ *
+ * If @value is found to be in normal form then it will be marked as
+ * being trusted.  If the value was already marked as being trusted then
+ * this function will immediately return %TRUE.
+ *
+ * Since: 2.24
+ **/
+gboolean
+g_variant_is_normal_form (GVariant *value)
+{
+  if (value->state & STATE_TRUSTED)
+    return TRUE;
+
+  g_variant_lock (value);
+
+  if (value->state & STATE_SERIALISED)
+    {
+      GVariantSerialised serialised = {
+        value->type_info,
+        (gpointer) value->contents.serialised.data,
+        value->size
+      };
+
+      if (g_variant_serialised_is_normal (serialised))
+        value->state |= STATE_TRUSTED;
+    }
+  else
+    {
+      gboolean normal = TRUE;
+      gsize i;
+
+      for (i = 0; i < value->contents.tree.n_children; i++)
+        normal &= g_variant_is_normal_form (value->contents.tree.children[i]);
+
+      if (normal)
+        value->state |= STATE_TRUSTED;
+    }
+
+  g_variant_unlock (value);
+
+  return (value->state & STATE_TRUSTED) != 0;
+}