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merge GVariantTypeInfo

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Ryan Lortie 2010-01-30 20:15:25 -05:00
parent 4c58a85dd1
commit 0f246e28ca
4 changed files with 1392 additions and 20 deletions
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2
glib/Makefile.am
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@ -172,6 +172,8 @@ libglib_2_0_la_SOURCES = \
gunicodeprivate.h \
gurifuncs.c \
gutils.c \
gvarianttypeinfo.h \
gvarianttypeinfo.c \
gvarianttype.c \
gdebug.h \
gprintf.c \

841
glib/gvarianttypeinfo.c Normal file
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@ -0,0 +1,841 @@
/*
* Copyright © 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.
*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
#include "gvarianttypeinfo.h"
#include <glib.h>
#include "galias.h"
/* < private >
* GVariantTypeInfo:
*
* This structure contains the necessary information to facilitate the
* serialisation and fast deserialisation of a given type of GVariant
* value. A GVariant instance holds a pointer to one of these
* structures to provide for efficient operation.
*
* The GVariantTypeInfo structures for all of the base types, plus the
* "variant" type are stored in a read-only static array.
*
* For container types, a hash table and reference counting is used to
* ensure that only one of these structures exists for any given type.
* In general, a container GVariantTypeInfo will exist for a given type
* only if one or more GVariant instances of that type exist or if
* another GVariantTypeInfo has that type as a subtype. For example, if
* a process contains a single GVariant instance with type "(asv)", then
* container GVariantTypeInfo structures will exist for "(asv)" and
* for "as" (note that "s" and "v" always exist in the static array).
*
* The trickiest part of GVariantTypeInfo (and in fact, the major reason
* for its existance) is the storage of somewhat magical constants that
* allow for O(1) lookups of items in tuples. This is described below.
*
* 'container_class' is set to 'a' or 'r' if the GVariantTypeInfo is
* contained inside of an ArrayInfo or TupleInfo, respectively. This
* allows the storage of the necessary additional information.
*
* 'fixed_size' is set to the fixed size of the type, if applicable, or
* 0 otherwise (since no type has a fixed size of 0).
*
* 'alignment' is set to one less than the alignment requirement for
* this type. This makes many operations much more convenient.
*/
struct _GVariantTypeInfo
{
gsize fixed_size;
guchar alignment;
guchar container_class;
};
/* Container types are reference counted. They also need to have their
* type string stored explicitly since it is not merely a single letter.
*/
typedef struct
{
GVariantTypeInfo info;
gchar *type_string;
gint ref_count;
} ContainerInfo;
/* For 'array' and 'maybe' types, we store some extra information on the
* end of the GVariantTypeInfo struct -- the element type (ie: "s" for
* "as"). The container GVariantTypeInfo structure holds a reference to
* the element typeinfo.
*/
typedef struct
{
ContainerInfo container;
GVariantTypeInfo *element;
} ArrayInfo;
/* For 'tuple' and 'dict entry' types, we store extra information for
* each member -- its type and how to find it inside the serialised data
* in O(1) time using 4 variables -- 'i', 'a', 'b', and 'c'. See the
* comment on GVariantMemberInfo in gvarianttypeinfo.h.
*/
typedef struct
{
ContainerInfo container;
GVariantMemberInfo *members;
gsize n_members;
} TupleInfo;
/* Hard-code the base types in a constant array */
static const GVariantTypeInfo g_variant_type_info_basic_table[24] = {
#define fixed_aligned(x) x, x - 1
#define unaligned 0, 0
#define aligned(x) 0, x - 1
/* 'b' */ { fixed_aligned(1) }, /* boolean */
/* 'c' */ { },
/* 'd' */ { fixed_aligned(8) }, /* double */
/* 'e' */ { },
/* 'f' */ { },
/* 'g' */ { unaligned }, /* signature string */
/* 'h' */ { fixed_aligned(4) }, /* file handle (int32) */
/* 'i' */ { fixed_aligned(4) }, /* int32 */
/* 'j' */ { },
/* 'k' */ { },
/* 'l' */ { },
/* 'm' */ { },
/* 'n' */ { fixed_aligned(2) }, /* int16 */
/* 'o' */ { unaligned }, /* object path string */
/* 'p' */ { },
/* 'q' */ { fixed_aligned(2) }, /* uint16 */
/* 'r' */ { },
/* 's' */ { unaligned }, /* string */
/* 't' */ { fixed_aligned(8) }, /* uint64 */
/* 'u' */ { fixed_aligned(4) }, /* uint32 */
/* 'v' */ { aligned(8) }, /* variant */
/* 'w' */ { },
/* 'x' */ { fixed_aligned(8) }, /* int64 */
/* 'y' */ { fixed_aligned(1) }, /* byte */
#undef fixed_aligned
#undef unaligned
#undef aligned
};
/* We need to have type strings to return for the base types. We store
* those in another array. Since all base type strings are single
* characters this is easy. By not storing pointers to strings into the
* GVariantTypeInfo itself, we save a bunch of relocations.
*/
static const char g_variant_type_info_basic_chars[24][2] = {
"b", " ", "d", " ", " ", "g", "h", "i", " ", " ", " ", " ",
"n", "o", " ", "q", " ", "s", "t", "u", "v", " ", "x", "y"
};
/* sanity checks to make debugging easier */
static void
g_variant_type_info_check (const GVariantTypeInfo *info,
char container_class)
{
g_assert (!container_class || info->container_class == container_class);
/* alignment can only be one of these */
g_assert (info->alignment == 0 || info->alignment == 1 ||
info->alignment == 3 || info->alignment == 7);
if (info->container_class)
{
ContainerInfo *container = (ContainerInfo *) info;
/* extra checks for containers */
g_assert_cmpint (container->ref_count, >, 0);
g_assert (container->type_string != NULL);
}
else
{
gint index;
/* if not a container, then ensure that it is a valid member of
* the basic types table
*/
index = info - g_variant_type_info_basic_table;
g_assert (G_N_ELEMENTS (g_variant_type_info_basic_table) == 24);
g_assert (G_N_ELEMENTS (g_variant_type_info_basic_chars) == 24);
g_assert (0 <= index && index < 24);
g_assert (g_variant_type_info_basic_chars[index][0] != ' ');
}
}
/* < private >
* g_variant_type_info_get_type_string:
* @info: a #GVariantTypeInfo
*
* Gets the type string for @info. The string is nul-terminated.
*/
const gchar *
g_variant_type_info_get_type_string (GVariantTypeInfo *info)
{
g_variant_type_info_check (info, 0);
if (info->container_class)
{
ContainerInfo *container = (ContainerInfo *) info;
/* containers have their type string stored inside them */
return container->type_string;
}
else
{
gint index;
/* look up the type string in the base type array. the call to
* g_variant_type_info_check() above already ensured validity.
*/
index = info - g_variant_type_info_basic_table;
return g_variant_type_info_basic_chars[index];
}
}
/* < private >
* g_variant_type_info_query:
* @info: a #GVariantTypeInfo
* @alignment: the location to store the alignment, or %NULL
* @fixed_size: the location to store the fixed size, or %NULL
*
* Queries @info to determine the alignment requirements and fixed size
* (if any) of the type.
*
* @fixed_size, if non-%NULL is set to the fixed size of the type, or 0
* to indicate that the type is a variable-sized type. No type has a
* fixed size of 0.
*
* @alignment, if non-%NULL, is set to one less than the required
* alignment of the type. For example, for a 32bit integer, @alignment
* would be set to 3. This allows you to round an integer up to the
* proper alignment by performing the following efficient calculation:
*
* offset += ((-offset) & alignment);
*/
void
g_variant_type_info_query (GVariantTypeInfo *info,
guint *alignment,
gsize *fixed_size)
{
g_variant_type_info_check (info, 0);
if (alignment)
*alignment = info->alignment;
if (fixed_size)
*fixed_size = info->fixed_size;
}
/* == array == */
#define ARRAY_INFO_CLASS 'a'
static ArrayInfo *
ARRAY_INFO (GVariantTypeInfo *info)
{
g_variant_type_info_check (info, ARRAY_INFO_CLASS);
return (ArrayInfo *) info;
}
static void
array_info_free (GVariantTypeInfo *info)
{
ArrayInfo *array_info;
g_assert (info->container_class == ARRAY_INFO_CLASS);
array_info = (ArrayInfo *) info;
g_variant_type_info_unref (array_info->element);
g_slice_free (ArrayInfo, array_info);
}
static ContainerInfo *
array_info_new (const GVariantType *type)
{
ArrayInfo *info;
info = g_slice_new (ArrayInfo);
info->container.info.container_class = ARRAY_INFO_CLASS;
info->element = g_variant_type_info_get (g_variant_type_element (type));
info->container.info.alignment = info->element->alignment;
info->container.info.fixed_size = 0;
return (ContainerInfo *) info;
}
/* < private >
* g_variant_type_info_element:
* @info: a #GVariantTypeInfo for an array or maybe type
*
* Returns the element type for the array or maybe type. A reference is
* not added, so the caller must add their own.
*/
GVariantTypeInfo *
g_variant_type_info_element (GVariantTypeInfo *info)
{
return ARRAY_INFO (info)->element;
}
/* < private >
* g_variant_type_query_element:
* @info: a #GVariantTypeInfo for an array or maybe type
* @alignment: the location to store the alignment, or %NULL
* @fixed_size: the location to store the fixed size, or %NULL
*
* Returns the alignment requires and fixed size (if any) for the
* element type of the array. This call is a convenience wrapper around
* g_variant_type_info_element() and g_variant_type_info_query().
*/
void
g_variant_type_info_query_element (GVariantTypeInfo *info,
guint *alignment,
gsize *fixed_size)
{
g_variant_type_info_query (ARRAY_INFO (info)->element,
alignment, fixed_size);
}
/* == tuple == */
#define TUPLE_INFO_CLASS 'r'
static TupleInfo *
TUPLE_INFO (GVariantTypeInfo *info)
{
g_variant_type_info_check (info, TUPLE_INFO_CLASS);
return (TupleInfo *) info;
}
static void
tuple_info_free (GVariantTypeInfo *info)
{
TupleInfo *tuple_info;
gint i;
g_assert (info->container_class == TUPLE_INFO_CLASS);
tuple_info = (TupleInfo *) info;
for (i = 0; i < tuple_info->n_members; i++)
g_variant_type_info_unref (tuple_info->members[i].type);
g_slice_free1 (sizeof (GVariantMemberInfo) * tuple_info->n_members,
tuple_info->members);
g_slice_free (TupleInfo, tuple_info);
}
static void
tuple_allocate_members (const GVariantType *type,
GVariantMemberInfo **members,
gsize *n_members)
{
const GVariantType *item_type;
gsize i = 0;
*n_members = g_variant_type_n_items (type);
*members = g_slice_alloc (sizeof (GVariantMemberInfo) * *n_members);
item_type = g_variant_type_first (type);
while (item_type)
{
(*members)[i++].type = g_variant_type_info_get (item_type);
item_type = g_variant_type_next (item_type);
}
g_assert (i == *n_members);
}
/* this is g_variant_type_info_query for a given member of the tuple.
* before the access is done, it is ensured that the item is within
* range and %FALSE is returned if not.
*/
static gboolean
tuple_get_item (TupleInfo *info,
GVariantMemberInfo *item,
gsize *d,
gsize *e)
{
if (&info->members[info->n_members] == item)
return FALSE;
*d = item->type->alignment;
*e = item->type->fixed_size;
return TRUE;
}
/* Read the documentation for #GVariantMemberInfo in gvarianttype.h
* before attempting to understand this.
*
* This function adds one set of "magic constant" values (for one item
* in the tuple) to the table.
*
* The algorithm in tuple_generate_table() calculates values of 'a', 'b'
* and 'c' for each item, such that the procedure for finding the item
* is to start at the end of the previous variable-sized item, add 'a',
* then round up to the nearest multiple of 'b', then then add 'c'.
* Note that 'b' is stored in the usual "one less than" form. ie:
*
* start = ROUND_UP(prev_end + a, (b + 1)) + c;
*
* We tweak these values a little to allow for a slightly easier
* computation and more compact storage.
*/
static void
tuple_table_append (GVariantMemberInfo **items,
gsize i,
gsize a,
gsize b,
gsize c)
{
GVariantMemberInfo *item = (*items)++;
/* We can shift multiples of the alignment size from 'c' into 'a'.
* As long as we're shifting whole multiples, it won't affect the
* result. This means that we can take the "aligned" portion off of
* 'c' and add it into 'a'.
*
* Imagine (for sake of clarity) that ROUND_10 rounds up to the
* nearest 10. It is clear that:
*
* ROUND_10(a) + c == ROUND_10(a + 10*(c / 10)) + (c % 10)
*
* ie: remove the 10s portion of 'c' and add it onto 'a'.
*
* To put some numbers on it, imagine we start with a = 34 and c = 27:
*
* ROUND_10(34) + 27 = 40 + 27 = 67
*
* but also, we can split 27 up into 20 and 7 and do this:
*
* ROUND_10(34 + 20) + 7 = ROUND_10(54) + 7 = 60 + 7 = 67
* ^^ ^
* without affecting the result. We do that here.
*
* This reduction in the size of 'c' means that we can store it in a
* gchar instead of a gsize. Due to how the structure is packed, this
* ends up saving us 'two pointer sizes' per item in each tuple when
* allocating using GSlice.
*/
a += ~b & c; /* take the "aligned" part of 'c' and add to 'a' */
c &= b; /* chop 'c' to contain only the unaligned part */
/* Finally, we made one last adjustment. Recall:
*
* start = ROUND_UP(prev_end + a, (b + 1)) + c;
*
* Forgetting the '+ c' for the moment:
*
* ROUND_UP(prev_end + a, (b + 1));
*
* we can do a "round up" operation by adding 1 less than the amount
* to round up to, then rounding down. ie:
*
* #define ROUND_UP(x, y) ROUND_DOWN(x + (y-1), y)
*
* Of course, for rounding down to a power of two, we can just mask
* out the appropriate number of low order bits:
*
* #define ROUND_DOWN(x, y) (x & ~(y - 1))
*
* Which gives us
*
* #define ROUND_UP(x, y) (x + (y - 1) & ~(y - 1))
*
* but recall that our alignment value 'b' is already "one less".
* This means that to round 'prev_end + a' up to 'b' we can just do:
*
* ((prev_end + a) + b) & ~b
*
* Associativity, and putting the 'c' back on:
*
* (prev_end + (a + b)) & ~b + c
*
* Now, since (a + b) is constant, we can just add 'b' to 'a' now and
* store that as the number to add to prev_end. Then we use ~b as the
* number to take a bitwise 'and' with. Finally, 'c' is added on.
*
* Note, however, that all the low order bits of the 'aligned' value
* are masked out and that all of the high order bits of 'c' have been
* "moved" to 'a' (in the previous step). This means that there are
* no overlapping bits in the addition -- so we can do a bitwise 'or'
* equivalently.
*
* This means that we can now compute the start address of a given
* item in the tuple using the algorithm given in the documentation
* for #GVariantMemberInfo:
*
* item_start = ((prev_end + a) & b) | c;
*/
item->i = i;
item->a = a + b;
item->b = ~b;
item->c = c;
}
static gsize
tuple_align (gsize offset,
guint alignment)
{
return offset + ((-offset) & alignment);
}
/* This function is the heart of the algorithm for calculating 'i', 'a',
* 'b' and 'c' for each item in the tuple.
*
* Imagine we want to find the start of the "i" in the type "(su(qx)ni)".
* That's a string followed by a uint32, then a tuple containing a
* uint16 and a int64, then an int16, then our "i". In order to get to
* our "i" we:
*
* Start at the end of the string, align to 4 (for the uint32), add 4.
* Align to 8, add 16 (for the tuple). Align to 2, add 2 (for the
* int16). Then we're there. It turns out that, given 3 simple rules,
* we can flatten this iteration into one addition, one alignment, then
* one more addition.
*
* The loop below plays through each item in the tuple, querying its
* alignment and fixed_size into 'd' and 'e', respectively. At all
* times the variables 'a', 'b', and 'c' are maintained such that in
* order to get to the current point, you add 'a', align to 'b' then add
* 'c'. 'b' is kept in "one less than" form. For each item, the proper
* alignment is applied to find the values of 'a', 'b' and 'c' to get to
* the start of that item. Those values are recorded into the table.
* The fixed size of the item (if applicable) is then added on.
*
* These 3 rules are how 'a', 'b' and 'c' are modified for alignment and
* addition of fixed size. They have been proven correct but are
* presented here, without proof:
*
* 1) in order to "align to 'd'" where 'd' is less than or equal to the
* largest level of alignment seen so far ('b'), you align 'c' to
* 'd'.
* 2) in order to "align to 'd'" where 'd' is greater than the largest
* level of alignment seen so far, you add 'c' aligned to 'b' to the
* value of 'a', set 'b' to 'd' (ie: increase the 'largest alignment
* seen') and reset 'c' to 0.
* 3) in order to "add 'e'", just add 'e' to 'c'.
*/
static void
tuple_generate_table (TupleInfo *info)
{
GVariantMemberInfo *items = info->members;
gsize i = -1, a = 0, b = 0, c = 0, d, e;
/* iterate over each item in the tuple.
* 'd' will be the alignment of the item (in one-less form)
* 'e' will be the fixed size (or 0 for variable-size items)
*/
while (tuple_get_item (info, items, &d, &e))
{
/* align to 'd' */
if (d <= b)
c = tuple_align (c, d); /* rule 1 */
else
a += tuple_align (c, b), b = d, c = 0; /* rule 2 */
/* the start of the item is at this point (ie: right after we
* have aligned for it). store this information in the table.
*/
tuple_table_append (&items, i, a, b, c);
/* "move past" the item by adding in its size. */
if (e == 0)
/* variable size:
*
* we'll have an offset stored to mark the end of this item, so
* just bump the offset index to give us a new starting point
* and reset all the counters.
*/
i++, a = b = c = 0;
else
/* fixed size */
c += e; /* rule 3 */
}
}
static void
tuple_set_base_info (TupleInfo *info)
{
GVariantTypeInfo *base = &info->container.info;
if (info->n_members > 0)
{
GVariantMemberInfo *m;
/* the alignment requirement of the tuple is the alignment
* requirement of its largest item.
*/
base->alignment = 0;
for (m = info->members; m < &info->members[info->n_members]; m++)
/* can find the max of a list of "one less than" powers of two
* by 'or'ing them
*/
base->alignment |= m->type->alignment;
m--; /* take 'm' back to the last item */
/* the structure only has a fixed size if no variable-size
* offsets are stored and the last item is fixed-sized too (since
* an offset is never stored for the last item).
*/
if (m->i == -1 && m->type->fixed_size)
/* in that case, the fixed size can be found by finding the
* start of the last item (in the usual way) and adding its
* fixed size.
*
* if a tuple has a fixed size then it is always a multiple of
* the alignment requirement (to make packing into arrays
* easier) so we round up to that here.
*/
base->fixed_size =
tuple_align (((m->a & m->b) | m->c) + m->type->fixed_size,
base->alignment);
else
/* else, the tuple is not fixed size */
base->fixed_size = 0;
}
else
{
/* the empty tuple: '()'.
*
* has a size of 1 and an no alignment requirement.
*
* It has a size of 1 (not 0) for two practical reasons:
*
* 1) So we can determine how many of them are in an array
* without dividing by zero or without other tricks.
*
* 2) Even if we had some trick to know the number of items in
* the array (as GVariant did at one time) this would open a
* potential denial of service attack: an attacker could send
* you an extremely small array (in terms of number of bytes)
* containing trillions of zero-sized items. If you iterated
* over this array you would effectively infinite-loop your
* program. By forcing a size of at least one, we bound the
* amount of computation done in response to a message to a
* reasonable function of the size of that message.
*/
base->alignment = 0;
base->fixed_size = 1;
}
}
static ContainerInfo *
tuple_info_new (const GVariantType *type)
{
TupleInfo *info;
info = g_slice_new (TupleInfo);
info->container.info.container_class = TUPLE_INFO_CLASS;
tuple_allocate_members (type, &info->members, &info->n_members);
tuple_generate_table (info);
tuple_set_base_info (info);
return (ContainerInfo *) info;
}
/* < private >
* g_variant_type_info_n_members:
* @info: a #GVariantTypeInfo for a tuple or dictionary entry type
*
* Returns the number of members in a tuple or dictionary entry type.
* For a dictionary entry this will always be 2.
*/
gsize
g_variant_type_info_n_members (GVariantTypeInfo *info)
{
return TUPLE_INFO (info)->n_members;
}
/* < private >
* g_variant_type_info_member_info:
* @info: a #GVariantTypeInfo for a tuple or dictionary entry type
* @index: the member to fetch information for
*
* Returns the #GVariantMemberInfo for a given member. See
* documentation for that structure for why you would want this
* information.
*
* @index must refer to a valid child (ie: strictly less than
* g_variant_type_info_n_members() returns).
*/
const GVariantMemberInfo *
g_variant_type_info_member_info (GVariantTypeInfo *info,
gsize index)
{
TupleInfo *tuple_info = TUPLE_INFO (info);
if (index < tuple_info->n_members)
return &tuple_info->members[index];
return NULL;
}
/* == new/ref/unref == */
static GStaticRecMutex g_variant_type_info_lock = G_STATIC_REC_MUTEX_INIT;
static GHashTable *g_variant_type_info_table;
/* < private >
* g_variant_type_info_get:
* @type: a #GVariantType
*
* Returns a reference to a #GVariantTypeInfo for @type.
*
* If an info structure already exists for this type, a new reference is
* returned. If not, the required calculations are performed and a new
* info structure is returned.
*
* It is appropriate to call g_variant_type_info_unref() on the return
* value.
*/
GVariantTypeInfo *
g_variant_type_info_get (const GVariantType *type)
{
char type_char;
type_char = g_variant_type_peek_string (type)[0];
if (type_char == G_VARIANT_TYPE_INFO_CHAR_MAYBE ||
type_char == G_VARIANT_TYPE_INFO_CHAR_ARRAY ||
type_char == G_VARIANT_TYPE_INFO_CHAR_TUPLE ||
type_char == G_VARIANT_TYPE_INFO_CHAR_DICT_ENTRY)
{
GVariantTypeInfo *info;
gchar *type_string;
if G_UNLIKELY (g_variant_type_info_table == NULL)
g_variant_type_info_table = g_hash_table_new (g_str_hash,
g_str_equal);
type_string = g_variant_type_dup_string (type);
g_static_rec_mutex_lock (&g_variant_type_info_lock);
info = g_hash_table_lookup (g_variant_type_info_table, type_string);
if (info == NULL)
{
ContainerInfo *container;
if (type_char == G_VARIANT_TYPE_INFO_CHAR_MAYBE ||
type_char == G_VARIANT_TYPE_INFO_CHAR_ARRAY)
{
container = array_info_new (type);
}
else /* tuple or dict entry */
{
container = tuple_info_new (type);
}
info = (GVariantTypeInfo *) container;
container->type_string = type_string;
container->ref_count = 1;
g_hash_table_insert (g_variant_type_info_table, type_string, info);
type_string = NULL;
}
else
g_variant_type_info_ref (info);
g_static_rec_mutex_unlock (&g_variant_type_info_lock);
g_variant_type_info_check (info, 0);
g_free (type_string);
return info;
}
else
{
const GVariantTypeInfo *info;
int index;
index = type_char - 'b';
g_assert (G_N_ELEMENTS (g_variant_type_info_basic_table) == 24);
g_assert_cmpint (0, <=, index);
g_assert_cmpint (index, <, 24);
info = g_variant_type_info_basic_table + index;
g_variant_type_info_check (info, 0);
return (GVariantTypeInfo *) info;
}
}
/* < private >
* g_variant_type_info_ref:
* @info: a #GVariantTypeInfo
*
* Adds a reference to @info.
*/
GVariantTypeInfo *
g_variant_type_info_ref (GVariantTypeInfo *info)
{
g_variant_type_info_check (info, 0);
if (info->container_class)
{
ContainerInfo *container = (ContainerInfo *) info;
g_assert_cmpint (container->ref_count, >, 0);
g_atomic_int_inc (&container->ref_count);
}
return info;
}
/* < private >
* g_variant_type_info_unref:
* @info: a #GVariantTypeInfo
*
* Releases a reference held on @info. This may result in @info being
* freed.
*/
void
g_variant_type_info_unref (GVariantTypeInfo *info)
{
g_variant_type_info_check (info, 0);
if (info->container_class)
{
ContainerInfo *container = (ContainerInfo *) info;
if (g_atomic_int_dec_and_test (&container->ref_count))
{
g_static_rec_mutex_lock (&g_variant_type_info_lock);
g_hash_table_remove (g_variant_type_info_table,
container->type_string);
g_static_rec_mutex_unlock (&g_variant_type_info_lock);
g_free (container->type_string);
if (info->container_class == ARRAY_INFO_CLASS)
array_info_free (info);
else if (info->container_class == TUPLE_INFO_CLASS)
tuple_info_free (info);
else
g_assert_not_reached ();
}
}
}

140
glib/gvarianttypeinfo.h Normal file
View File

@ -0,0 +1,140 @@
/*
* Copyright © 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.
*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
#ifndef __G_VARIANT_TYPE_INFO_H__
#define __G_VARIANT_TYPE_INFO_H__
#include <glib/gvarianttype.h>
#define G_VARIANT_TYPE_INFO_CHAR_MAYBE 'm'
#define G_VARIANT_TYPE_INFO_CHAR_ARRAY 'a'
#define G_VARIANT_TYPE_INFO_CHAR_TUPLE '('
#define G_VARIANT_TYPE_INFO_CHAR_DICT_ENTRY '{'
#define G_VARIANT_TYPE_INFO_CHAR_VARIANT 'v'
#define g_variant_type_info_get_type_char(info) \
(g_variant_type_info_get_type_string(info)[0])
typedef struct _GVariantTypeInfo GVariantTypeInfo;
/* < private >
* GVariantMemberInfo:
*
* This structure describes how to construct a GVariant instance
* corresponding to a given child of a tuple or dictionary entry in a
* very short constant time. It contains the typeinfo of the child,
* along with 4 constants that allow the bounds of the child's
* serialised data within the container's serialised data to be found
* very efficiently.
*
* Since dictionary entries are serialised as if they were tuples of 2
* items, the term "tuple" will be used here in the general sense to
* refer to tuples and dictionary entries.
*
* BACKGROUND:
* The serialised data for a tuple contains an array of "offsets" at
* the end. There is one "offset" in this array for each
* variable-sized item in the tuple (except for the last one). The
* offset points to the end point of that item's serialised data. The
* procedure for finding the start point is described below. An
* offset is not needed for the last item because the end point of the
* last item is merely the end point of the container itself (after
* the offsets array has been accounted for). An offset is not needed
* for fixed-sized items (like integers) because, due to their fixed
* size, the end point is a constant addition to the start point.
*
* It is clear that the starting point of a given item in the tuple is
* determined by the items that preceed it in the tuple. Logically,
* the start point of a particular item in a given type of tuple can
* be determined entirely by the end point of the nearest
* variable-sized item that came before it (or from the start of the
* container itself in case there is no preceeding variable-sized
* item). In the case of "(isis)" for example, in order to find out
* the start point of the last string, one must start at the end point
* of the first string, align to 4 (for the integer's alignment) and
* then add 4 (for storing the integer). That's the point where the
* string starts (since no special alignment is required for strings).
*
* Of course, this process requires iterating over the types in the
* tuple up to the item of interest. As it turns out, it is possible
* to determine 3 constants 'a', 'b', and 'c' for each item in the
* tuple, such that, given the ending offset of the nearest previous
* variable-sized item (prev_end), a very simple calculation can be
* performed to determine the start of the item of interest.
*
* The constants in this structure are used as follows:
*
* First, among the array of offets contained in the tuple, 'i' is the
* index of the offset that refers to the end of the variable-sized item
* preceeding the item of interest. If no variable-sized items preceed
* this item, then 'i' will be -1.
*
* Let 'prev_end' be the end offset of the previous item (or 0 in the
* case that there was no such item). The start address of this item
* can then be calculate using 'a', 'b', and 'c':
*
* item_start = ((prev_end + a) & b) | c;
*
* For details about how 'a', 'b' and 'c' are calculated, see the
* comments at the point of the implementation in gvariantypeinfo.c.
*/
typedef struct
{
GVariantTypeInfo *type;
gsize i, a;
gint8 b, c;
} GVariantMemberInfo;
/* query */
G_GNUC_INTERNAL
const gchar * g_variant_type_info_get_type_string (GVariantTypeInfo *typeinfo);
G_GNUC_INTERNAL
void g_variant_type_info_query (GVariantTypeInfo *typeinfo,
guint *alignment,
gsize *size);
/* array */
G_GNUC_INTERNAL
GVariantTypeInfo * g_variant_type_info_element (GVariantTypeInfo *typeinfo);
G_GNUC_INTERNAL
void g_variant_type_info_query_element (GVariantTypeInfo *typeinfo,
guint *alignment,
gsize *size);
/* structure */
G_GNUC_INTERNAL
gsize g_variant_type_info_n_members (GVariantTypeInfo *typeinfo);
G_GNUC_INTERNAL
const GVariantMemberInfo * g_variant_type_info_member_info (GVariantTypeInfo *typeinfo,
gsize index);
/* new/ref/unref */
G_GNUC_INTERNAL
GVariantTypeInfo * g_variant_type_info_get (const GVariantType *type);
G_GNUC_INTERNAL
GVariantTypeInfo * g_variant_type_info_ref (GVariantTypeInfo *typeinfo);
G_GNUC_INTERNAL
void g_variant_type_info_unref (GVariantTypeInfo *typeinfo);
#endif /* __G_VARIANT_TYPE_INFO_H__ */

429
glib/tests/gvarianttype.c
View File

@ -27,20 +27,22 @@ randomly (gdouble prob)
}
/* corecursion */
static GVariantType *append_tuple_type_string (GString *, GString *, gint);
static GVariantType *
append_tuple_type_string (GString *, GString *, gboolean, gint);
/* append a random GVariantType to a GString
* append a description of the type to another GString
* return what the type is
*/
static GVariantType *
append_type_string (GString *string,
GString *description,
gint depth)
append_type_string (GString *string,
GString *description,
gboolean definite,
gint depth)
{
if (!depth-- || randomly (0.3))
{
gchar b = BASIC[g_test_rand_int_range (0, N_BASIC)];
gchar b = BASIC[g_test_rand_int_range (0, N_BASIC - definite)];
g_string_append_c (string, b);
g_string_append_c (description, b);
@ -82,7 +84,7 @@ append_type_string (GString *string,
{
GVariantType *result;
switch (g_test_rand_int_range (0, 7))
switch (g_test_rand_int_range (0, definite ? 5 : 7))
{
case 0:
{
@ -90,7 +92,8 @@ append_type_string (GString *string,
g_string_append_c (string, 'a');
g_string_append (description, "a of ");
element = append_type_string (string, description, depth);
element = append_type_string (string, description,
definite, depth);
result = g_variant_type_new_array (element);
g_variant_type_free (element);
}
@ -104,7 +107,8 @@ append_type_string (GString *string,
g_string_append_c (string, 'm');
g_string_append (description, "m of ");
element = append_type_string (string, description, depth);
element = append_type_string (string, description,
definite, depth);
result = g_variant_type_new_maybe (element);
g_variant_type_free (element);
}
@ -113,7 +117,8 @@ append_type_string (GString *string,
break;
case 2:
result = append_tuple_type_string (string, description, depth);
result = append_tuple_type_string (string, description,
definite, depth);
g_assert (g_variant_type_is_tuple (result));
break;
@ -124,9 +129,9 @@ append_type_string (GString *string,
g_string_append_c (string, '{');
g_string_append (description, "e of [");
key = append_type_string (string, description, 0);
key = append_type_string (string, description, definite, 0);
g_string_append (description, ", ");
value = append_type_string (string, description, depth);
value = append_type_string (string, description, definite, depth);
g_string_append_c (description, ']');
g_string_append_c (string, '}');
result = g_variant_type_new_dict_entry (key, value);
@ -167,9 +172,10 @@ append_type_string (GString *string,
}
static GVariantType *
append_tuple_type_string (GString *string,
GString *description,
gint depth)
append_tuple_type_string (GString *string,
GString *description,
gboolean definite,
gint depth)
{
GVariantType *result, *other_result;
GVariantType **types;
@ -184,7 +190,7 @@ append_tuple_type_string (GString *string,
for (i = 0; i < size; i++)
{
types[i] = append_type_string (string, description, depth);
types[i] = append_type_string (string, description, definite, depth);
if (i < size - 1)
g_string_append (description, ", ");
@ -493,13 +499,13 @@ generate_subtype (const gchar *type_string)
/* then store the replacement in the GString */
if (type_string[l] == 'r')
replacement = append_tuple_type_string (result, junk, 3);
replacement = append_tuple_type_string (result, junk, FALSE, 3);
else if (type_string[l] == '?')
replacement = append_type_string (result, junk, 0);
replacement = append_type_string (result, junk, FALSE, 0);
else if (type_string[l] == '*')
replacement = append_type_string (result, junk, 3);
replacement = append_type_string (result, junk, FALSE, 3);
else
g_assert_not_reached ();
@ -584,7 +590,7 @@ test_gvarianttype (void)
*
* exercises type constructor functions and g_variant_type_copy()
*/
type = append_type_string (type_string, description, 6);
type = append_type_string (type_string, description, FALSE, 6);
/* convert the type string to a type and ensure that it is equal
* to the one produced with the type constructor routines
@ -630,7 +636,7 @@ test_gvarianttype (void)
/* concatenate another type to the type string and ensure that
* the result is recognised as being invalid
*/
other_type = append_type_string (type_string, description, 2);
other_type = append_type_string (type_string, description, FALSE, 2);
g_string_free (description, TRUE);
g_string_free (type_string, TRUE);
@ -639,12 +645,395 @@ test_gvarianttype (void)
}
}
#undef G_GNUC_INTERNAL
#define G_GNUC_INTERNAL static
#define DISABLE_VISIBILITY
#include <glib/gvarianttypeinfo.c>
#define ALIGNED(x, y) (((x + (y - 1)) / y) * y)
/* do our own calculation of the fixed_size and alignment of a type
* using a simple algorithm to make sure the "fancy" one in the
* implementation is correct.
*/
static void
calculate_type_info (const GVariantType *type,
gsize *fixed_size,
guint *alignment)
{
if (g_variant_type_is_array (type) ||
g_variant_type_is_maybe (type))
{
calculate_type_info (g_variant_type_element (type), NULL, alignment);
if (fixed_size)
*fixed_size = 0;
}
else if (g_variant_type_is_tuple (type) ||
g_variant_type_is_dict_entry (type))
{
if (g_variant_type_n_items (type))
{
const GVariantType *sub;
gboolean variable;
gsize size;
guint al;
variable = FALSE;
size = 0;
al = 0;
sub = g_variant_type_first (type);
do
{
gsize this_fs;
guint this_al;
calculate_type_info (sub, &this_fs, &this_al);
al = MAX (al, this_al);
if (!this_fs)
{
variable = TRUE;
size = 0;
}
if (!variable)
{
size = ALIGNED (size, this_al);
size += this_fs;
}
}
while ((sub = g_variant_type_next (sub)));
size = ALIGNED (size, al);
if (alignment)
*alignment = al;
if (fixed_size)
*fixed_size = size;
}
else
{
if (fixed_size)
*fixed_size = 1;
if (alignment)
*alignment = 1;
}
}
else
{
gint fs, al;
if (g_variant_type_equal (type, G_VARIANT_TYPE_BOOLEAN) ||
g_variant_type_equal (type, G_VARIANT_TYPE_BYTE))
{
al = fs = 1;
}
else if (g_variant_type_equal (type, G_VARIANT_TYPE_INT16) ||
g_variant_type_equal (type, G_VARIANT_TYPE_UINT16))
{
al = fs = 2;
}
else if (g_variant_type_equal (type, G_VARIANT_TYPE_INT32) ||
g_variant_type_equal (type, G_VARIANT_TYPE_UINT32) ||
g_variant_type_equal (type, G_VARIANT_TYPE_HANDLE))
{
al = fs = 4;
}
else if (g_variant_type_equal (type, G_VARIANT_TYPE_INT64) ||
g_variant_type_equal (type, G_VARIANT_TYPE_UINT64) ||
g_variant_type_equal (type, G_VARIANT_TYPE_DOUBLE))
{
al = fs = 8;
}
else if (g_variant_type_equal (type, G_VARIANT_TYPE_STRING) ||
g_variant_type_equal (type, G_VARIANT_TYPE_OBJECT_PATH) ||
g_variant_type_equal (type, G_VARIANT_TYPE_SIGNATURE))
{
al = 1;
fs = 0;
}
else if (g_variant_type_equal (type, G_VARIANT_TYPE_VARIANT))
{
al = 8;
fs = 0;
}
else
g_assert_not_reached ();
if (fixed_size)
*fixed_size = fs;
if (alignment)
*alignment = al;
}
}
/* same as the describe_type() function above, but iterates over
* typeinfo instead of types.
*/
static gchar *
describe_info (GVariantTypeInfo *info)
{
gchar *result;
switch (g_variant_type_info_get_type_char (info))
{
case G_VARIANT_TYPE_INFO_CHAR_MAYBE:
{
gchar *element;
element = describe_info (g_variant_type_info_element (info));
result = g_strdup_printf ("m of %s", element);
g_free (element);
}
break;
case G_VARIANT_TYPE_INFO_CHAR_ARRAY:
{
gchar *element;
element = describe_info (g_variant_type_info_element (info));
result = g_strdup_printf ("a of %s", element);
g_free (element);
}
break;
case G_VARIANT_TYPE_INFO_CHAR_TUPLE:
{
const gchar *sep = "";
GString *string;
gint length;
gint i;
string = g_string_new ("t of [");
length = g_variant_type_info_n_members (info);
for (i = 0; i < length; i++)
{
const GVariantMemberInfo *minfo;
gchar *subtype;
g_string_append (string, sep);
sep = ", ";
minfo = g_variant_type_info_member_info (info, i);
subtype = describe_info (minfo->type);
g_string_append (string, subtype);
g_free (subtype);
}
g_string_append_c (string, ']');
result = g_string_free (string, FALSE);
}
break;
case G_VARIANT_TYPE_INFO_CHAR_DICT_ENTRY:
{
const GVariantMemberInfo *keyinfo, *valueinfo;
gchar *key, *value;
g_assert_cmpint (g_variant_type_info_n_members (info), ==, 2);
keyinfo = g_variant_type_info_member_info (info, 0);
valueinfo = g_variant_type_info_member_info (info, 1);
key = describe_info (keyinfo->type);
value = describe_info (valueinfo->type);
result = g_strjoin ("", "e of [", key, ", ", value, "]", NULL);
g_free (key);
g_free (value);
}
break;
case G_VARIANT_TYPE_INFO_CHAR_VARIANT:
result = g_strdup ("V");
break;
default:
result = g_strdup (g_variant_type_info_get_type_string (info));
g_assert_cmpint (strlen (result), ==, 1);
break;
}
return result;
}
/* check that the O(1) method of calculating offsets meshes with the
* results of simple iteration.
*/
static void
check_offsets (GVariantTypeInfo *info,
const GVariantType *type)
{
gint flavour;
gint length;
length = g_variant_type_info_n_members (info);
g_assert_cmpint (length, ==, g_variant_type_n_items (type));
/* the 'flavour' is the low order bits of the ending point of
* variable-size items in the tuple. this lets us test that the type
* info is correct for various starting alignments.
*/
for (flavour = 0; flavour < 8; flavour++)
{
const GVariantType *subtype;
gsize last_offset_index;
gsize last_offset;
gsize position;
gint i;
subtype = g_variant_type_first (type);
last_offset_index = -1;
last_offset = 0;
position = 0;
/* go through the tuple, keeping track of our position */
for (i = 0; i < length; i++)
{
gsize fixed_size;
guint alignment;
calculate_type_info (subtype, &fixed_size, &alignment);
position = ALIGNED (position, alignment);
/* compare our current aligned position (ie: the start of this
* item) to the start offset that would be calculated if we
* used the type info
*/
{
const GVariantMemberInfo *member;
gsize start;
member = g_variant_type_info_member_info (info, i);
g_assert_cmpint (member->i, ==, last_offset_index);
/* do the calculation using the typeinfo */
start = last_offset;
start += member->a;
start &= member->b;
start |= member->c;
/* did we reach the same spot? */
g_assert_cmpint (start, ==, position);
}
if (fixed_size)
{
/* fixed size. add that size. */
position += fixed_size;
}
else
{
/* variable size. do the flavouring. */
while ((position & 0x7) != flavour)
position++;
/* and store the offset, just like it would be in the
* serialised data.
*/
last_offset = position;
last_offset_index++;
}
/* next type */
subtype = g_variant_type_next (subtype);
}
/* make sure we used up exactly all the types */
g_assert (subtype == NULL);
}
}
static void
test_gvarianttypeinfo (void)
{
gint i;
for (i = 0; i < 2000; i++)
{
GString *type_string, *description;
gsize fixed_size1, fixed_size2;
guint alignment1, alignment2;
GVariantTypeInfo *info;
GVariantType *type;
gchar *desc;
type_string = g_string_new (NULL);
description = g_string_new (NULL);
/* random type */
type = append_type_string (type_string, description, TRUE, 6);
/* create a typeinfo for it */
info = g_variant_type_info_get (type);
/* make sure the typeinfo has the right type string */
g_assert_cmpstr (g_variant_type_info_get_type_string (info), ==,
type_string->str);
/* calculate the alignment and fixed size, compare to the
* typeinfo's calculations
*/
calculate_type_info (type, &fixed_size1, &alignment1);
g_variant_type_info_query (info, &alignment2, &fixed_size2);
g_assert_cmpint (fixed_size1, ==, fixed_size2);
g_assert_cmpint (alignment1, ==, alignment2 + 1);
/* test the iteration functions over typeinfo structures by
* "describing" the typeinfo and verifying equality.
*/
desc = describe_info (info);
g_assert_cmpstr (desc, ==, description->str);
/* do extra checks for containers */
if (g_variant_type_is_array (type) ||
g_variant_type_is_maybe (type))
{
const GVariantType *element;
gsize efs1, efs2;
guint ea1, ea2;
element = g_variant_type_element (type);
calculate_type_info (element, &efs1, &ea1);
g_variant_type_info_query_element (info, &ea2, &efs2);
g_assert_cmpint (efs1, ==, efs2);
g_assert_cmpint (ea1, ==, ea2 + 1);
g_assert_cmpint (ea1, ==, alignment1);
g_assert_cmpint (0, ==, fixed_size1);
}
else if (g_variant_type_is_tuple (type) ||
g_variant_type_is_dict_entry (type))
{
/* make sure the "magic constants" are working */
check_offsets (info, type);
}
g_string_free (type_string, TRUE);
g_string_free (description, TRUE);
g_variant_type_info_unref (info);
g_variant_type_free (type);
g_free (desc);
}
}
int
main (int argc, char **argv)
{
g_test_init (&argc, &argv, NULL);
g_test_add_func ("/gvariant/type", test_gvarianttype);
g_test_add_func ("/gvariant/typeinfo", test_gvarianttypeinfo);
return g_test_run ();
}