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glib/glib/gvariant-serialiser.c
Christian Hergert 18a33f72db introspection: use (nullable) or (optional) instead of (allow-none) 
If we have an input parameter (or return value) we need to use (nullable).
However, if it is an (inout) or (out) parameter, (optional) is sufficient.

It looks like (nullable) could be used for everything according to the
Annotation documentation, but (optional) is more specific.
2016-11-22 14:14:37 -08:00

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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 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, see <http://www.gnu.org/licenses/>.
*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
/* Prologue {{{1 */
#include "config.h"
#include "gvariant-serialiser.h"
#include <glib/gtestutils.h>
#include <glib/gstrfuncs.h>
#include <glib/gtypes.h>
#include <string.h>
/* GVariantSerialiser
*
* After this prologue section, this file has roughly 2 parts.
*
* The first part is split up into sections according to various
* container types. Maybe, Array, Tuple, Variant. The Maybe and Array
* sections are subdivided for element types being fixed or
* variable-sized types.
*
* Each section documents the format of that particular type of
* container and implements 5 functions for dealing with it:
*
* n_children:
* - determines (according to serialised data) how many child values
* are inside a particular container value.
*
* get_child:
* - gets the type of and the serialised data corresponding to a
* given child value within the container value.
*
* needed_size:
* - determines how much space would be required to serialise a
* container of this type, containing the given children so that
* buffers can be preallocated before serialising.
*
* serialise:
* - write the serialised data for a container of this type,
* containing the given children, to a buffer.
*
* is_normal:
* - check the given data to ensure that it is in normal form. For a
* given set of child values, there is exactly one normal form for
* the serialised data of a container. Other forms are possible
* while maintaining the same children (for example, by inserting
* something other than zero bytes as padding) but only one form is
* the normal form.
*
* The second part contains the main entry point for each of the above 5
* functions and logic to dispatch it to the handler for the appropriate
* container type code.
*
* The second part also contains a routine to byteswap serialised
* values. This code makes use of the n_children() and get_child()
* functions above to do its work so no extra support is needed on a
* per-container-type basis.
*
* There is also additional code for checking for normal form. All
* numeric types are always in normal form since the full range of
* values is permitted (eg: 0 to 255 is a valid byte). Special checks
* need to be performed for booleans (only 0 or 1 allowed), strings
* (properly nul-terminated) and object paths and signature strings
* (meeting the D-Bus specification requirements).
*/
/* < private >
* GVariantSerialised:
* @type_info: the #GVariantTypeInfo of this value
* @data: (nullable): the serialised data of this value, or %NULL
* @size: the size of this value
*
* A structure representing a GVariant in serialised form. This
* structure is used with #GVariantSerialisedFiller functions and as the
* primary interface to the serialiser. See #GVariantSerialisedFiller
* for a description of its use there.
*
* When used with the serialiser API functions, the following invariants
* apply to all #GVariantTypeSerialised structures passed to and
* returned from the serialiser.
*
* @type_info must be non-%NULL.
*
* @data must be properly aligned for the type described by @type_info.
*
* If @type_info describes a fixed-sized type then @size must always be
* equal to the fixed size of that type.
*
* For fixed-sized types (and only fixed-sized types), @data may be
* %NULL even if @size is non-zero. This happens when a framing error
* occurs while attempting to extract a fixed-sized value out of a
* variable-sized container. There is no data to return for the
* fixed-sized type, yet @size must be non-zero. The effect of this
* combination should be as if @data were a pointer to an
* appropriately-sized zero-filled region.
*/
/* < private >
* g_variant_serialised_check:
* @serialised: a #GVariantSerialised struct
*
* Checks @serialised for validity according to the invariants described
* above.
*/
static void
g_variant_serialised_check (GVariantSerialised serialised)
{
gsize fixed_size;
guint alignment;
g_assert (serialised.type_info != NULL);
g_variant_type_info_query (serialised.type_info, &alignment, &fixed_size);
if (fixed_size)
g_assert_cmpint (serialised.size, ==, fixed_size);
else
g_assert (serialised.size == 0 || serialised.data != NULL);
/* Depending on the native alignment requirements of the machine, the
* compiler will insert either 3 or 7 padding bytes after the char.
* This will result in the sizeof() the struct being 12 or 16.
* Subtract 9 to get 3 or 7 which is a nice bitmask to apply to get
* the alignment bits that we "care about" being zero: in the
* 4-aligned case, we care about 2 bits, and in the 8-aligned case, we
* care about 3 bits.
*/
alignment &= sizeof (struct {
char a;
union {
guint64 x;
void *y;
gdouble z;
} b;
}
) - 9;
/* Some OSes (FreeBSD is a known example) have a malloc() that returns
* unaligned memory if you request small sizes. 'malloc (1);', for
* example, has been seen to return pointers aligned to 6 mod 16.
*
* Check if this is a small allocation and return without enforcing
* the alignment assertion if this is the case.
*/
if (serialised.size <= alignment)
return;
g_assert_cmpint (alignment & (gsize) serialised.data, ==, 0);
}
/* < private >
* GVariantSerialisedFiller:
* @serialised: a #GVariantSerialised instance to fill
* @data: data from the children array
*
* This function is called back from g_variant_serialiser_needed_size()
* and g_variant_serialiser_serialise(). It fills in missing details
* from a partially-complete #GVariantSerialised.
*
* The @data parameter passed back to the function is one of the items
* that was passed to the serialiser in the @children array. It
* represents a single child item of the container that is being
* serialised. The information filled in to @serialised is the
* information for this child.
*
* If the @type_info field of @serialised is %NULL then the callback
* function must set it to the type information corresponding to the
* type of the child. No reference should be added. If it is non-%NULL
* then the callback should assert that it is equal to the actual type
* of the child.
*
* If the @size field is zero then the callback must fill it in with the
* required amount of space to store the serialised form of the child.
* If it is non-zero then the callback should assert that it is equal to
* the needed size of the child.
*
* If @data is non-%NULL then it points to a space that is properly
* aligned for and large enough to store the serialised data of the
* child. The callback must store the serialised form of the child at
* @data.
*
* If the child value is another container then the callback will likely
* recurse back into the serialiser by calling
* g_variant_serialiser_needed_size() to determine @size and
* g_variant_serialiser_serialise() to write to @data.
*/
/* PART 1: Container types {{{1
*
* This section contains the serialiser implementation functions for
* each container type.
*/
/* Maybe {{{2
*
* Maybe types are handled depending on if the element type of the maybe
* type is a fixed-sized or variable-sized type. Although all maybe
* types themselves are variable-sized types, herein, a maybe value with
* a fixed-sized element type is called a "fixed-sized maybe" for
* convenience and a maybe value with a variable-sized element type is
* called a "variable-sized maybe".
*/
/* Fixed-sized Maybe {{{3
*
* The size of a maybe value with a fixed-sized element type is either 0
* or equal to the fixed size of its element type. The case where the
* size of the maybe value is zero corresponds to the "Nothing" case and
* the case where the size of the maybe value is equal to the fixed size
* of the element type corresponds to the "Just" case; in that case, the
* serialised data of the child value forms the entire serialised data
* of the maybe value.
*
* In the event that a fixed-sized maybe value is presented with a size
* that is not equal to the fixed size of the element type then the
* value must be taken to be "Nothing".
*/
static gsize
gvs_fixed_sized_maybe_n_children (GVariantSerialised value)
{
gsize element_fixed_size;
g_variant_type_info_query_element (value.type_info, NULL,
&element_fixed_size);
return (element_fixed_size == value.size) ? 1 : 0;
}
static GVariantSerialised
gvs_fixed_sized_maybe_get_child (GVariantSerialised value,
gsize index_)
{
/* the child has the same bounds as the
* container, so just update the type.
*/
value.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_ref (value.type_info);
return value;
}
static gsize
gvs_fixed_sized_maybe_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
if (n_children)
{
gsize element_fixed_size;
g_variant_type_info_query_element (type_info, NULL,
&element_fixed_size);
return element_fixed_size;
}
else
return 0;
}
static void
gvs_fixed_sized_maybe_serialise (GVariantSerialised value,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
if (n_children)
{
GVariantSerialised child = { NULL, value.data, value.size };
gvs_filler (&child, children[0]);
}
}
static gboolean
gvs_fixed_sized_maybe_is_normal (GVariantSerialised value)
{
if (value.size > 0)
{
gsize element_fixed_size;
g_variant_type_info_query_element (value.type_info,
NULL, &element_fixed_size);
if (value.size != element_fixed_size)
return FALSE;
/* proper element size: "Just". recurse to the child. */
value.type_info = g_variant_type_info_element (value.type_info);
return g_variant_serialised_is_normal (value);
}
/* size of 0: "Nothing" */
return TRUE;
}
/* Variable-sized Maybe
*
* The size of a maybe value with a variable-sized element type is
* either 0 or strictly greater than 0. The case where the size of the
* maybe value is zero corresponds to the "Nothing" case and the case
* where the size of the maybe value is greater than zero corresponds to
* the "Just" case; in that case, the serialised data of the child value
* forms the first part of the serialised data of the maybe value and is
* followed by a single zero byte. This zero byte is always appended,
* regardless of any zero bytes that may already be at the end of the
* serialised ata of the child value.
*/
static gsize
gvs_variable_sized_maybe_n_children (GVariantSerialised value)
{
return (value.size > 0) ? 1 : 0;
}
static GVariantSerialised
gvs_variable_sized_maybe_get_child (GVariantSerialised value,
gsize index_)
{
/* remove the padding byte and update the type. */
value.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_ref (value.type_info);
value.size--;
/* if it's zero-sized then it may as well be NULL */
if (value.size == 0)
value.data = NULL;
return value;
}
static gsize
gvs_variable_sized_maybe_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
if (n_children)
{
GVariantSerialised child = { 0, };
gvs_filler (&child, children[0]);
return child.size + 1;
}
else
return 0;
}
static void
gvs_variable_sized_maybe_serialise (GVariantSerialised value,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
if (n_children)
{
GVariantSerialised child = { NULL, value.data, value.size - 1 };
/* write the data for the child. */
gvs_filler (&child, children[0]);
value.data[child.size] = '\0';
}
}
static gboolean
gvs_variable_sized_maybe_is_normal (GVariantSerialised value)
{
if (value.size == 0)
return TRUE;
if (value.data[value.size - 1] != '\0')
return FALSE;
value.type_info = g_variant_type_info_element (value.type_info);
value.size--;
return g_variant_serialised_is_normal (value);
}
/* Arrays {{{2
*
* Just as with maybe types, array types are handled depending on if the
* element type of the array type is a fixed-sized or variable-sized
* type. Similar to maybe types, for convenience, an array value with a
* fixed-sized element type is called a "fixed-sized array" and an array
* value with a variable-sized element type is called a "variable sized
* array".
*/
/* Fixed-sized Array {{{3
*
* For fixed sized arrays, the serialised data is simply a concatenation
* of the serialised data of each element, in order. Since fixed-sized
* values always have a fixed size that is a multiple of their alignment
* requirement no extra padding is required.
*
* In the event that a fixed-sized array is presented with a size that
* is not an integer multiple of the element size then the value of the
* array must be taken as being empty.
*/
static gsize
gvs_fixed_sized_array_n_children (GVariantSerialised value)
{
gsize element_fixed_size;
g_variant_type_info_query_element (value.type_info, NULL,
&element_fixed_size);
if (value.size % element_fixed_size == 0)
return value.size / element_fixed_size;
return 0;
}
static GVariantSerialised
gvs_fixed_sized_array_get_child (GVariantSerialised value,
gsize index_)
{
GVariantSerialised child = { 0, };
child.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_query (child.type_info, NULL, &child.size);
child.data = value.data + (child.size * index_);
g_variant_type_info_ref (child.type_info);
return child;
}
static gsize
gvs_fixed_sized_array_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
gsize element_fixed_size;
g_variant_type_info_query_element (type_info, NULL, &element_fixed_size);
return element_fixed_size * n_children;
}
static void
gvs_fixed_sized_array_serialise (GVariantSerialised value,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
GVariantSerialised child = { 0, };
gsize i;
child.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_query (child.type_info, NULL, &child.size);
child.data = value.data;
for (i = 0; i < n_children; i++)
{
gvs_filler (&child, children[i]);
child.data += child.size;
}
}
static gboolean
gvs_fixed_sized_array_is_normal (GVariantSerialised value)
{
GVariantSerialised child = { 0, };
child.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_query (child.type_info, NULL, &child.size);
if (value.size % child.size != 0)
return FALSE;
for (child.data = value.data;
child.data < value.data + value.size;
child.data += child.size)
{
if (!g_variant_serialised_is_normal (child))
return FALSE;
}
return TRUE;
}
/* Variable-sized Array {{{3
*
* Variable sized arrays, containing variable-sized elements, must be
* able to determine the boundaries between the elements. The items
* cannot simply be concatenated. Additionally, we are faced with the
* fact that non-fixed-sized values do not necessarily have a size that
* is a multiple of their alignment requirement, so we may need to
* insert zero-filled padding.
*
* While it is possible to find the start of an item by starting from
* the end of the item before it and padding for alignment, it is not
* generally possible to do the reverse operation. For this reason, we
* record the end point of each element in the array.
*
* GVariant works in terms of "offsets". An offset is a pointer to a
* boundary between two bytes. In 4 bytes of serialised data, there
* would be 5 possible offsets: one at the start ('0'), one between each
* pair of adjacent bytes ('1', '2', '3') and one at the end ('4').
*
* The numeric value of an offset is an unsigned integer given relative
* to the start of the serialised data of the array. Offsets are always
* stored in little endian byte order and are always only as big as they
* need to be. For example, in 255 bytes of serialised data, there are
* 256 offsets. All possibilities can be stored in an 8 bit unsigned
* integer. In 256 bytes of serialised data, however, there are 257
* possible offsets so 16 bit integers must be used. The size of an
* offset is always a power of 2.
*
* The offsets are stored at the end of the serialised data of the
* array. They are simply concatenated on without any particular
* alignment. The size of the offsets is included in the size of the
* serialised data for purposes of determining the size of the offsets.
* This presents a possibly ambiguity; in certain cases, a particular
* value of array could have two different serialised forms.
*
* Imagine an array containing a single string of 253 bytes in length
* (so, 254 bytes including the nul terminator). Now the offset must be
* written. If an 8 bit offset is written, it will bring the size of
* the array's serialised data to 255 -- which means that the use of an
* 8 bit offset was valid. If a 16 bit offset is used then the total
* size of the array will be 256 -- which means that the use of a 16 bit
* offset was valid. Although both of these will be accepted by the
* deserialiser, only the smaller of the two is considered to be in
* normal form and that is the one that the serialiser must produce.
*/
/* bytes may be NULL if (size == 0). */
static inline gsize
gvs_read_unaligned_le (guchar *bytes,
guint size)
{
union
{
guchar bytes[GLIB_SIZEOF_SIZE_T];
gsize integer;
} tmpvalue;
tmpvalue.integer = 0;
if (bytes != NULL)
memcpy (&tmpvalue.bytes, bytes, size);
return GSIZE_FROM_LE (tmpvalue.integer);
}
static inline void
gvs_write_unaligned_le (guchar *bytes,
gsize value,
guint size)
{
union
{
guchar bytes[GLIB_SIZEOF_SIZE_T];
gsize integer;
} tmpvalue;
tmpvalue.integer = GSIZE_TO_LE (value);
memcpy (bytes, &tmpvalue.bytes, size);
}
static guint
gvs_get_offset_size (gsize size)
{
if (size > G_MAXUINT32)
return 8;
else if (size > G_MAXUINT16)
return 4;
else if (size > G_MAXUINT8)
return 2;
else if (size > 0)
return 1;
return 0;
}
static gsize
gvs_calculate_total_size (gsize body_size,
gsize offsets)
{
if (body_size + 1 * offsets <= G_MAXUINT8)
return body_size + 1 * offsets;
if (body_size + 2 * offsets <= G_MAXUINT16)
return body_size + 2 * offsets;
if (body_size + 4 * offsets <= G_MAXUINT32)
return body_size + 4 * offsets;
return body_size + 8 * offsets;
}
static gsize
gvs_variable_sized_array_n_children (GVariantSerialised value)
{
gsize offsets_array_size;
gsize offset_size;
gsize last_end;
if (value.size == 0)
return 0;
offset_size = gvs_get_offset_size (value.size);
last_end = gvs_read_unaligned_le (value.data + value.size -
offset_size, offset_size);
if (last_end > value.size)
return 0;
offsets_array_size = value.size - last_end;
if (offsets_array_size % offset_size)
return 0;
return offsets_array_size / offset_size;
}
static GVariantSerialised
gvs_variable_sized_array_get_child (GVariantSerialised value,
gsize index_)
{
GVariantSerialised child = { 0, };
gsize offset_size;
gsize last_end;
gsize start;
gsize end;
child.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_ref (child.type_info);
offset_size = gvs_get_offset_size (value.size);
last_end = gvs_read_unaligned_le (value.data + value.size -
offset_size, offset_size);
if (index_ > 0)
{
guint alignment;
start = gvs_read_unaligned_le (value.data + last_end +
(offset_size * (index_ - 1)),
offset_size);
g_variant_type_info_query (child.type_info, &alignment, NULL);
start += (-start) & alignment;
}
else
start = 0;
end = gvs_read_unaligned_le (value.data + last_end +
(offset_size * index_),
offset_size);
if (start < end && end <= value.size)
{
child.data = value.data + start;
child.size = end - start;
}
return child;
}
static gsize
gvs_variable_sized_array_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
guint alignment;
gsize offset;
gsize i;
g_variant_type_info_query (type_info, &alignment, NULL);
offset = 0;
for (i = 0; i < n_children; i++)
{
GVariantSerialised child = { 0, };
offset += (-offset) & alignment;
gvs_filler (&child, children[i]);
offset += child.size;
}
return gvs_calculate_total_size (offset, n_children);
}
static void
gvs_variable_sized_array_serialise (GVariantSerialised value,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
guchar *offset_ptr;
gsize offset_size;
guint alignment;
gsize offset;
gsize i;
g_variant_type_info_query (value.type_info, &alignment, NULL);
offset_size = gvs_get_offset_size (value.size);
offset = 0;
offset_ptr = value.data + value.size - offset_size * n_children;
for (i = 0; i < n_children; i++)
{
GVariantSerialised child = { 0, };
while (offset & alignment)
value.data[offset++] = '\0';
child.data = value.data + offset;
gvs_filler (&child, children[i]);
offset += child.size;
gvs_write_unaligned_le (offset_ptr, offset, offset_size);
offset_ptr += offset_size;
}
}
static gboolean
gvs_variable_sized_array_is_normal (GVariantSerialised value)
{
GVariantSerialised child = { 0, };
gsize offsets_array_size;
guchar *offsets_array;
guint offset_size;
guint alignment;
gsize last_end;
gsize length;
gsize offset;
gsize i;
if (value.size == 0)
return TRUE;
offset_size = gvs_get_offset_size (value.size);
last_end = gvs_read_unaligned_le (value.data + value.size -
offset_size, offset_size);
if (last_end > value.size)
return FALSE;
offsets_array_size = value.size - last_end;
if (offsets_array_size % offset_size)
return FALSE;
offsets_array = value.data + value.size - offsets_array_size;
length = offsets_array_size / offset_size;
if (length == 0)
return FALSE;
child.type_info = g_variant_type_info_element (value.type_info);
g_variant_type_info_query (child.type_info, &alignment, NULL);
offset = 0;
for (i = 0; i < length; i++)
{
gsize this_end;
this_end = gvs_read_unaligned_le (offsets_array + offset_size * i,
offset_size);
if (this_end < offset || this_end > last_end)
return FALSE;
while (offset & alignment)
{
if (!(offset < this_end && value.data[offset] == '\0'))
return FALSE;
offset++;
}
child.data = value.data + offset;
child.size = this_end - offset;
if (child.size == 0)
child.data = NULL;
if (!g_variant_serialised_is_normal (child))
return FALSE;
offset = this_end;
}
g_assert (offset == last_end);
return TRUE;
}
/* Tuples {{{2
*
* Since tuples can contain a mix of variable- and fixed-sized items,
* they are, in terms of serialisation, a hybrid of variable-sized and
* fixed-sized arrays.
*
* Offsets are only stored for variable-sized items. Also, since the
* number of items in a tuple is known from its type, we are able to
* know exactly how many offsets to expect in the serialised data (and
* therefore how much space is taken up by the offset array). This
* means that we know where the end of the serialised data for the last
* item is -- we can just subtract the size of the offset array from the
* total size of the tuple. For this reason, the last item in the tuple
* doesn't need an offset stored.
*
* Tuple offsets are stored in reverse. This design choice allows
* iterator-based deserialisers to be more efficient.
*
* Most of the "heavy lifting" here is handled by the GVariantTypeInfo
* for the tuple. See the notes in gvarianttypeinfo.h.
*/
static gsize
gvs_tuple_n_children (GVariantSerialised value)
{
return g_variant_type_info_n_members (value.type_info);
}
static GVariantSerialised
gvs_tuple_get_child (GVariantSerialised value,
gsize index_)
{
const GVariantMemberInfo *member_info;
GVariantSerialised child = { 0, };
gsize offset_size;
gsize start, end;
member_info = g_variant_type_info_member_info (value.type_info, index_);
child.type_info = g_variant_type_info_ref (member_info->type_info);
offset_size = gvs_get_offset_size (value.size);
/* tuples are the only (potentially) fixed-sized containers, so the
* only ones that have to deal with the possibility of having %NULL
* data with a non-zero %size if errors occurred elsewhere.
*/
if G_UNLIKELY (value.data == NULL && value.size != 0)
{
g_variant_type_info_query (child.type_info, NULL, &child.size);
/* this can only happen in fixed-sized tuples,
* so the child must also be fixed sized.
*/
g_assert (child.size != 0);
child.data = NULL;
return child;
}
if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_OFFSET)
{
if (offset_size * (member_info->i + 2) > value.size)
return child;
}
else
{
if (offset_size * (member_info->i + 1) > value.size)
{
/* if the child is fixed size, return its size.
* if child is not fixed-sized, return size = 0.
*/
g_variant_type_info_query (child.type_info, NULL, &child.size);
return child;
}
}
if (member_info->i + 1)
start = gvs_read_unaligned_le (value.data + value.size -
offset_size * (member_info->i + 1),
offset_size);
else
start = 0;
start += member_info->a;
start &= member_info->b;
start |= member_info->c;
if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_LAST)
end = value.size - offset_size * (member_info->i + 1);
else if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_FIXED)
{
gsize fixed_size;
g_variant_type_info_query (child.type_info, NULL, &fixed_size);
end = start + fixed_size;
child.size = fixed_size;
}
else /* G_VARIANT_MEMBER_ENDING_OFFSET */
end = gvs_read_unaligned_le (value.data + value.size -
offset_size * (member_info->i + 2),
offset_size);
if (start < end && end <= value.size)
{
child.data = value.data + start;
child.size = end - start;
}
return child;
}
static gsize
gvs_tuple_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
const GVariantMemberInfo *member_info = NULL;
gsize fixed_size;
gsize offset;
gsize i;
g_variant_type_info_query (type_info, NULL, &fixed_size);
if (fixed_size)
return fixed_size;
offset = 0;
for (i = 0; i < n_children; i++)
{
guint alignment;
member_info = g_variant_type_info_member_info (type_info, i);
g_variant_type_info_query (member_info->type_info,
&alignment, &fixed_size);
offset += (-offset) & alignment;
if (fixed_size)
offset += fixed_size;
else
{
GVariantSerialised child = { 0, };
gvs_filler (&child, children[i]);
offset += child.size;
}
}
return gvs_calculate_total_size (offset, member_info->i + 1);
}
static void
gvs_tuple_serialise (GVariantSerialised value,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
gsize offset_size;
gsize offset;
gsize i;
offset_size = gvs_get_offset_size (value.size);
offset = 0;
for (i = 0; i < n_children; i++)
{
const GVariantMemberInfo *member_info;
GVariantSerialised child = { 0, };
guint alignment;
member_info = g_variant_type_info_member_info (value.type_info, i);
g_variant_type_info_query (member_info->type_info, &alignment, NULL);
while (offset & alignment)
value.data[offset++] = '\0';
child.data = value.data + offset;
gvs_filler (&child, children[i]);
offset += child.size;
if (member_info->ending_type == G_VARIANT_MEMBER_ENDING_OFFSET)
{
value.size -= offset_size;
gvs_write_unaligned_le (value.data + value.size,
offset, offset_size);
}
}
while (offset < value.size)
value.data[offset++] = '\0';
}
static gboolean
gvs_tuple_is_normal (GVariantSerialised value)
{
guint offset_size;
gsize offset_ptr;
gsize length;
gsize offset;
gsize i;
/* as per the comment in gvs_tuple_get_child() */
if G_UNLIKELY (value.data == NULL && value.size != 0)
return FALSE;
offset_size = gvs_get_offset_size (value.size);
length = g_variant_type_info_n_members (value.type_info);
offset_ptr = value.size;
offset = 0;
for (i = 0; i < length; i++)
{
const GVariantMemberInfo *member_info;
GVariantSerialised child;
gsize fixed_size;
guint alignment;
gsize end;
member_info = g_variant_type_info_member_info (value.type_info, i);
child.type_info = member_info->type_info;
g_variant_type_info_query (child.type_info, &alignment, &fixed_size);
while (offset & alignment)
{
if (offset > value.size || value.data[offset] != '\0')
return FALSE;
offset++;
}
child.data = value.data + offset;
switch (member_info->ending_type)
{
case G_VARIANT_MEMBER_ENDING_FIXED:
end = offset + fixed_size;
break;
case G_VARIANT_MEMBER_ENDING_LAST:
end = offset_ptr;
break;
case G_VARIANT_MEMBER_ENDING_OFFSET:
offset_ptr -= offset_size;
if (offset_ptr < offset)
return FALSE;
end = gvs_read_unaligned_le (value.data + offset_ptr, offset_size);
break;
default:
g_assert_not_reached ();
}
if (end < offset || end > offset_ptr)
return FALSE;
child.size = end - offset;
if (child.size == 0)
child.data = NULL;
if (!g_variant_serialised_is_normal (child))
return FALSE;
offset = end;
}
{
gsize fixed_size;
guint alignment;
g_variant_type_info_query (value.type_info, &alignment, &fixed_size);
if (fixed_size)
{
g_assert (fixed_size == value.size);
g_assert (offset_ptr == value.size);
if (i == 0)
{
if (value.data[offset++] != '\0')
return FALSE;
}
else
{
while (offset & alignment)
if (value.data[offset++] != '\0')
return FALSE;
}
g_assert (offset == value.size);
}
}
return offset_ptr == offset;
}
/* Variants {{{2
*
* Variants are stored by storing the serialised data of the child,
* followed by a '\0' character, followed by the type string of the
* child.
*
* In the case that a value is presented that contains no '\0'
* character, or doesn't have a single well-formed definite type string
* following that character, the variant must be taken as containing the
* unit tuple: ().
*/
static inline gsize
gvs_variant_n_children (GVariantSerialised value)
{
return 1;
}
static inline GVariantSerialised
gvs_variant_get_child (GVariantSerialised value,
gsize index_)
{
GVariantSerialised child = { 0, };
/* NOTE: not O(1) and impossible for it to be... */
if (value.size)
{
/* find '\0' character */
for (child.size = value.size - 1; child.size; child.size--)
if (value.data[child.size] == '\0')
break;
/* ensure we didn't just hit the start of the string */
if (value.data[child.size] == '\0')
{
const gchar *type_string = (gchar *) &value.data[child.size + 1];
const gchar *limit = (gchar *) &value.data[value.size];
const gchar *end;
if (g_variant_type_string_scan (type_string, limit, &end) &&
end == limit)
{
const GVariantType *type = (GVariantType *) type_string;
if (g_variant_type_is_definite (type))
{
gsize fixed_size;
child.type_info = g_variant_type_info_get (type);
if (child.size != 0)
/* only set to non-%NULL if size > 0 */
child.data = value.data;
g_variant_type_info_query (child.type_info,
NULL, &fixed_size);
if (!fixed_size || fixed_size == child.size)
return child;
g_variant_type_info_unref (child.type_info);
}
}
}
}
child.type_info = g_variant_type_info_get (G_VARIANT_TYPE_UNIT);
child.data = NULL;
child.size = 1;
return child;
}
static inline gsize
gvs_variant_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
GVariantSerialised child = { 0, };
const gchar *type_string;
gvs_filler (&child, children[0]);
type_string = g_variant_type_info_get_type_string (child.type_info);
return child.size + 1 + strlen (type_string);
}
static inline void
gvs_variant_serialise (GVariantSerialised value,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
GVariantSerialised child = { 0, };
const gchar *type_string;
child.data = value.data;
gvs_filler (&child, children[0]);
type_string = g_variant_type_info_get_type_string (child.type_info);
value.data[child.size] = '\0';
memcpy (value.data + child.size + 1, type_string, strlen (type_string));
}
static inline gboolean
gvs_variant_is_normal (GVariantSerialised value)
{
GVariantSerialised child;
gboolean normal;
child = gvs_variant_get_child (value, 0);
normal = (child.data != NULL || child.size == 0) &&
g_variant_serialised_is_normal (child);
g_variant_type_info_unref (child.type_info);
return normal;
}
/* PART 2: Serialiser API {{{1
*
* This is the implementation of the API of the serialiser as advertised
* in gvariant-serialiser.h.
*/
/* Dispatch Utilities {{{2
*
* These macros allow a given function (for example,
* g_variant_serialiser_serialise) to be dispatched to the appropriate
* type-specific function above (fixed/variable-sized maybe,
* fixed/variable-sized array, tuple or variant).
*/
#define DISPATCH_FIXED(type_info, before, after) \
{ \
gsize fixed_size; \
\
g_variant_type_info_query_element (type_info, NULL, \
&fixed_size); \
\
if (fixed_size) \
{ \
before ## fixed_sized ## after \
} \
else \
{ \
before ## variable_sized ## after \
} \
}
#define DISPATCH_CASES(type_info, before, after) \
switch (g_variant_type_info_get_type_char (type_info)) \
{ \
case G_VARIANT_TYPE_INFO_CHAR_MAYBE: \
DISPATCH_FIXED (type_info, before, _maybe ## after) \
\
case G_VARIANT_TYPE_INFO_CHAR_ARRAY: \
DISPATCH_FIXED (type_info, before, _array ## after) \
\
case G_VARIANT_TYPE_INFO_CHAR_DICT_ENTRY: \
case G_VARIANT_TYPE_INFO_CHAR_TUPLE: \
{ \
before ## tuple ## after \
} \
\
case G_VARIANT_TYPE_INFO_CHAR_VARIANT: \
{ \
before ## variant ## after \
} \
}
/* Serialiser entry points {{{2
*
* These are the functions that are called in order for the serialiser
* to do its thing.
*/
/* < private >
* g_variant_serialised_n_children:
* @serialised: a #GVariantSerialised
*
* For serialised data that represents a container value (maybes,
* tuples, arrays, variants), determine how many child items are inside
* that container.
*
* Returns: the number of children
*/
gsize
g_variant_serialised_n_children (GVariantSerialised serialised)
{
g_variant_serialised_check (serialised);
DISPATCH_CASES (serialised.type_info,
return gvs_/**/,/**/_n_children (serialised);
)
g_assert_not_reached ();
}
/* < private >
* g_variant_serialised_get_child:
* @serialised: a #GVariantSerialised
* @index_: the index of the child to fetch
*
* Extracts a child from a serialised data representing a container
* value.
*
* It is an error to call this function with an index out of bounds.
*
* If the result .data == %NULL and .size > 0 then there has been an
* error extracting the requested fixed-sized value. This number of
* zero bytes needs to be allocated instead.
*
* In the case that .data == %NULL and .size == 0 then a zero-sized
* item of a variable-sized type is being returned.
*
* .data is never non-%NULL if size is 0.
*
* Returns: a #GVariantSerialised for the child
*/
GVariantSerialised
g_variant_serialised_get_child (GVariantSerialised serialised,
gsize index_)
{
GVariantSerialised child;
g_variant_serialised_check (serialised);
if G_LIKELY (index_ < g_variant_serialised_n_children (serialised))
{
DISPATCH_CASES (serialised.type_info,
child = gvs_/**/,/**/_get_child (serialised, index_);
g_assert (child.size || child.data == NULL);
g_variant_serialised_check (child);
return child;
)
g_assert_not_reached ();
}
g_error ("Attempt to access item %"G_GSIZE_FORMAT
" in a container with only %"G_GSIZE_FORMAT" items",
index_, g_variant_serialised_n_children (serialised));
}
/* < private >
* g_variant_serialiser_serialise:
* @serialised: a #GVariantSerialised, properly set up
* @gvs_filler: the filler function
* @children: an array of child items
* @n_children: the size of @children
*
* Writes data in serialised form.
*
* The type_info field of @serialised must be filled in to type info for
* the type that we are serialising.
*
* The size field of @serialised must be filled in with the value
* returned by a previous call to g_variant_serialiser_needed_size().
*
* The data field of @serialised must be a pointer to a properly-aligned
* memory region large enough to serialise into (ie: at least as big as
* the size field).
*
* This function is only resonsible for serialising the top-level
* container. @gvs_filler is called on each child of the container in
* order for all of the data of that child to be filled in.
*/
void
g_variant_serialiser_serialise (GVariantSerialised serialised,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
g_variant_serialised_check (serialised);
DISPATCH_CASES (serialised.type_info,
gvs_/**/,/**/_serialise (serialised, gvs_filler,
children, n_children);
return;
)
g_assert_not_reached ();
}
/* < private >
* g_variant_serialiser_needed_size:
* @type_info: the type to serialise for
* @gvs_filler: the filler function
* @children: an array of child items
* @n_children: the size of @children
*
* Determines how much memory would be needed to serialise this value.
*
* This function is only resonsible for performing calculations for the
* top-level container. @gvs_filler is called on each child of the
* container in order to determine its size.
*/
gsize
g_variant_serialiser_needed_size (GVariantTypeInfo *type_info,
GVariantSerialisedFiller gvs_filler,
const gpointer *children,
gsize n_children)
{
DISPATCH_CASES (type_info,
return gvs_/**/,/**/_needed_size (type_info, gvs_filler,
children, n_children);
)
g_assert_not_reached ();
}
/* Byteswapping {{{2 */
/* < private >
* g_variant_serialised_byteswap:
* @value: a #GVariantSerialised
*
* Byte-swap serialised data. The result of this function is only
* well-defined if the data is in normal form.
*/
void
g_variant_serialised_byteswap (GVariantSerialised serialised)
{
gsize fixed_size;
guint alignment;
g_variant_serialised_check (serialised);
if (!serialised.data)
return;
/* the types we potentially need to byteswap are
* exactly those with alignment requirements.
*/
g_variant_type_info_query (serialised.type_info, &alignment, &fixed_size);
if (!alignment)
return;
/* if fixed size and alignment are equal then we are down
* to the base integer type and we should swap it. the
* only exception to this is if we have a tuple with a
* single item, and then swapping it will be OK anyway.
*/
if (alignment + 1 == fixed_size)
{
switch (fixed_size)
{
case 2:
{
guint16 *ptr = (guint16 *) serialised.data;
g_assert_cmpint (serialised.size, ==, 2);
*ptr = GUINT16_SWAP_LE_BE (*ptr);
}
return;
case 4:
{
guint32 *ptr = (guint32 *) serialised.data;
g_assert_cmpint (serialised.size, ==, 4);
*ptr = GUINT32_SWAP_LE_BE (*ptr);
}
return;
case 8:
{
guint64 *ptr = (guint64 *) serialised.data;
g_assert_cmpint (serialised.size, ==, 8);
*ptr = GUINT64_SWAP_LE_BE (*ptr);
}
return;
default:
g_assert_not_reached ();
}
}
/* else, we have a container that potentially contains
* some children that need to be byteswapped.
*/
else
{
gsize children, i;
children = g_variant_serialised_n_children (serialised);
for (i = 0; i < children; i++)
{
GVariantSerialised child;
child = g_variant_serialised_get_child (serialised, i);
g_variant_serialised_byteswap (child);
g_variant_type_info_unref (child.type_info);
}
}
}
/* Normal form checking {{{2 */
/* < private >
* g_variant_serialised_is_normal:
* @serialised: a #GVariantSerialised
*
* Determines, recursively if @serialised is in normal form. There is
* precisely one normal form of serialised data for each possible value.
*
* It is possible that multiple byte sequences form the serialised data
* for a given value if, for example, the padding bytes are filled in
* with something other than zeros, but only one form is the normal
* form.
*/
gboolean
g_variant_serialised_is_normal (GVariantSerialised serialised)
{
DISPATCH_CASES (serialised.type_info,
return gvs_/**/,/**/_is_normal (serialised);
)
if (serialised.data == NULL)
return FALSE;
/* some hard-coded terminal cases */
switch (g_variant_type_info_get_type_char (serialised.type_info))
{
case 'b': /* boolean */
return serialised.data[0] < 2;
case 's': /* string */
return g_variant_serialiser_is_string (serialised.data,
serialised.size);
case 'o':
return g_variant_serialiser_is_object_path (serialised.data,
serialised.size);
case 'g':
return g_variant_serialiser_is_signature (serialised.data,
serialised.size);
default:
/* all of the other types are fixed-sized numerical types for
* which all possible values are valid (including various NaN
* representations for floating point values).
*/
return TRUE;
}
}
/* Validity-checking functions {{{2
*
* Checks if strings, object paths and signature strings are valid.
*/
/* < private >
* g_variant_serialiser_is_string:
* @data: a possible string
* @size: the size of @data
*
* Ensures that @data is a valid string with a nul terminator at the end
* and no nul bytes embedded.
*/
gboolean
g_variant_serialiser_is_string (gconstpointer data,
gsize size)
{
const gchar *expected_end;
const gchar *end;
if (size == 0)
return FALSE;
expected_end = ((gchar *) data) + size - 1;
if (*expected_end != '\0')
return FALSE;
g_utf8_validate (data, size, &end);
return end == expected_end;
}
/* < private >
* g_variant_serialiser_is_object_path:
* @data: a possible D-Bus object path
* @size: the size of @data
*
* Performs the checks for being a valid string.
*
* Also, ensures that @data is a valid DBus object path, as per the D-Bus
* specification.
*/
gboolean
g_variant_serialiser_is_object_path (gconstpointer data,
gsize size)
{
const gchar *string = data;
gsize i;
if (!g_variant_serialiser_is_string (data, size))
return FALSE;
/* The path must begin with an ASCII '/' (integer 47) character */
if (string[0] != '/')
return FALSE;
for (i = 1; string[i]; i++)
/* Each element must only contain the ASCII characters
* "[A-Z][a-z][0-9]_"
*/
if (g_ascii_isalnum (string[i]) || string[i] == '_')
;
/* must consist of elements separated by slash characters. */
else if (string[i] == '/')
{
/* No element may be the empty string. */
/* Multiple '/' characters cannot occur in sequence. */
if (string[i - 1] == '/')
return FALSE;
}
else
return FALSE;
/* A trailing '/' character is not allowed unless the path is the
* root path (a single '/' character).
*/
if (i > 1 && string[i - 1] == '/')
return FALSE;
return TRUE;
}
/* < private >
* g_variant_serialiser_is_signature:
* @data: a possible D-Bus signature
* @size: the size of @data
*
* Performs the checks for being a valid string.
*
* Also, ensures that @data is a valid D-Bus type signature, as per the
* D-Bus specification.
*/
gboolean
g_variant_serialiser_is_signature (gconstpointer data,
gsize size)
{
const gchar *string = data;
gsize first_invalid;
if (!g_variant_serialiser_is_string (data, size))
return FALSE;
/* make sure no non-definite characters appear */
first_invalid = strspn (string, "ybnqiuxthdvasog(){}");
if (string[first_invalid])
return FALSE;
/* make sure each type string is well-formed */
while (*string)
if (!g_variant_type_string_scan (string, NULL, &string))
return FALSE;
return TRUE;
}
/* Epilogue {{{1 */
/* vim:set foldmethod=marker: */
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