2 * Copyright © 2008 Ryan Lortie
3 * Copyright © 2010 Codethink Limited
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
20 * Author: Ryan Lortie <desrt@desrt.ca>
23 #include "gvarianttypeinfo.h"
25 #include <glib/gtestutils.h>
26 #include <glib/gthread.h>
27 #include <glib/ghash.h>
34 * This structure contains the necessary information to facilitate the
35 * serialisation and fast deserialisation of a given type of GVariant
36 * value. A GVariant instance holds a pointer to one of these
37 * structures to provide for efficient operation.
39 * The GVariantTypeInfo structures for all of the base types, plus the
40 * "variant" type are stored in a read-only static array.
42 * For container types, a hash table and reference counting is used to
43 * ensure that only one of these structures exists for any given type.
44 * In general, a container GVariantTypeInfo will exist for a given type
45 * only if one or more GVariant instances of that type exist or if
46 * another GVariantTypeInfo has that type as a subtype. For example, if
47 * a process contains a single GVariant instance with type "(asv)", then
48 * container GVariantTypeInfo structures will exist for "(asv)" and
49 * for "as" (note that "s" and "v" always exist in the static array).
51 * The trickiest part of GVariantTypeInfo (and in fact, the major reason
52 * for its existance) is the storage of somewhat magical constants that
53 * allow for O(1) lookups of items in tuples. This is described below.
55 * 'container_class' is set to 'a' or 'r' if the GVariantTypeInfo is
56 * contained inside of an ArrayInfo or TupleInfo, respectively. This
57 * allows the storage of the necessary additional information.
59 * 'fixed_size' is set to the fixed size of the type, if applicable, or
60 * 0 otherwise (since no type has a fixed size of 0).
62 * 'alignment' is set to one less than the alignment requirement for
63 * this type. This makes many operations much more convenient.
65 struct _GVariantTypeInfo
69 guchar container_class;
72 /* Container types are reference counted. They also need to have their
73 * type string stored explicitly since it is not merely a single letter.
77 GVariantTypeInfo info;
83 /* For 'array' and 'maybe' types, we store some extra information on the
84 * end of the GVariantTypeInfo struct -- the element type (ie: "s" for
85 * "as"). The container GVariantTypeInfo structure holds a reference to
86 * the element typeinfo.
90 ContainerInfo container;
92 GVariantTypeInfo *element;
95 /* For 'tuple' and 'dict entry' types, we store extra information for
96 * each member -- its type and how to find it inside the serialised data
97 * in O(1) time using 4 variables -- 'i', 'a', 'b', and 'c'. See the
98 * comment on GVariantMemberInfo in gvarianttypeinfo.h.
102 ContainerInfo container;
104 GVariantMemberInfo *members;
109 /* Hard-code the base types in a constant array */
110 static const GVariantTypeInfo g_variant_type_info_basic_table[24] = {
111 #define fixed_aligned(x) x, x - 1
112 #define unaligned 0, 0
113 #define aligned(x) 0, x - 1
114 /* 'b' */ { fixed_aligned(1) }, /* boolean */
116 /* 'd' */ { fixed_aligned(8) }, /* double */
119 /* 'g' */ { unaligned }, /* signature string */
120 /* 'h' */ { fixed_aligned(4) }, /* file handle (int32) */
121 /* 'i' */ { fixed_aligned(4) }, /* int32 */
126 /* 'n' */ { fixed_aligned(2) }, /* int16 */
127 /* 'o' */ { unaligned }, /* object path string */
129 /* 'q' */ { fixed_aligned(2) }, /* uint16 */
131 /* 's' */ { unaligned }, /* string */
132 /* 't' */ { fixed_aligned(8) }, /* uint64 */
133 /* 'u' */ { fixed_aligned(4) }, /* uint32 */
134 /* 'v' */ { aligned(8) }, /* variant */
136 /* 'x' */ { fixed_aligned(8) }, /* int64 */
137 /* 'y' */ { fixed_aligned(1) }, /* byte */
143 /* We need to have type strings to return for the base types. We store
144 * those in another array. Since all base type strings are single
145 * characters this is easy. By not storing pointers to strings into the
146 * GVariantTypeInfo itself, we save a bunch of relocations.
148 static const char g_variant_type_info_basic_chars[24][2] = {
149 "b", " ", "d", " ", " ", "g", "h", "i", " ", " ", " ", " ",
150 "n", "o", " ", "q", " ", "s", "t", "u", "v", " ", "x", "y"
153 /* sanity checks to make debugging easier */
155 g_variant_type_info_check (const GVariantTypeInfo *info,
156 char container_class)
158 g_assert (!container_class || info->container_class == container_class);
160 /* alignment can only be one of these */
161 g_assert (info->alignment == 0 || info->alignment == 1 ||
162 info->alignment == 3 || info->alignment == 7);
164 if (info->container_class)
166 ContainerInfo *container = (ContainerInfo *) info;
168 /* extra checks for containers */
169 g_assert_cmpint (container->ref_count, >, 0);
170 g_assert (container->type_string != NULL);
176 /* if not a container, then ensure that it is a valid member of
177 * the basic types table
179 index = info - g_variant_type_info_basic_table;
181 g_assert (G_N_ELEMENTS (g_variant_type_info_basic_table) == 24);
182 g_assert (G_N_ELEMENTS (g_variant_type_info_basic_chars) == 24);
183 g_assert (0 <= index && index < 24);
184 g_assert (g_variant_type_info_basic_chars[index][0] != ' ');
189 * g_variant_type_info_get_type_string:
190 * @info: a #GVariantTypeInfo
192 * Gets the type string for @info. The string is nul-terminated.
195 g_variant_type_info_get_type_string (GVariantTypeInfo *info)
197 g_variant_type_info_check (info, 0);
199 if (info->container_class)
201 ContainerInfo *container = (ContainerInfo *) info;
203 /* containers have their type string stored inside them */
204 return container->type_string;
210 /* look up the type string in the base type array. the call to
211 * g_variant_type_info_check() above already ensured validity.
213 index = info - g_variant_type_info_basic_table;
215 return g_variant_type_info_basic_chars[index];
220 * g_variant_type_info_query:
221 * @info: a #GVariantTypeInfo
222 * @alignment: the location to store the alignment, or %NULL
223 * @fixed_size: the location to store the fixed size, or %NULL
225 * Queries @info to determine the alignment requirements and fixed size
226 * (if any) of the type.
228 * @fixed_size, if non-%NULL is set to the fixed size of the type, or 0
229 * to indicate that the type is a variable-sized type. No type has a
232 * @alignment, if non-%NULL, is set to one less than the required
233 * alignment of the type. For example, for a 32bit integer, @alignment
234 * would be set to 3. This allows you to round an integer up to the
235 * proper alignment by performing the following efficient calculation:
237 * offset += ((-offset) & alignment);
240 g_variant_type_info_query (GVariantTypeInfo *info,
244 g_variant_type_info_check (info, 0);
247 *alignment = info->alignment;
250 *fixed_size = info->fixed_size;
254 #define ARRAY_INFO_CLASS 'a'
256 ARRAY_INFO (GVariantTypeInfo *info)
258 g_variant_type_info_check (info, ARRAY_INFO_CLASS);
260 return (ArrayInfo *) info;
264 array_info_free (GVariantTypeInfo *info)
266 ArrayInfo *array_info;
268 g_assert (info->container_class == ARRAY_INFO_CLASS);
269 array_info = (ArrayInfo *) info;
271 g_variant_type_info_unref (array_info->element);
272 g_slice_free (ArrayInfo, array_info);
275 static ContainerInfo *
276 array_info_new (const GVariantType *type)
280 info = g_slice_new (ArrayInfo);
281 info->container.info.container_class = ARRAY_INFO_CLASS;
283 info->element = g_variant_type_info_get (g_variant_type_element (type));
284 info->container.info.alignment = info->element->alignment;
285 info->container.info.fixed_size = 0;
287 return (ContainerInfo *) info;
291 * g_variant_type_info_element:
292 * @info: a #GVariantTypeInfo for an array or maybe type
294 * Returns the element type for the array or maybe type. A reference is
295 * not added, so the caller must add their own.
298 g_variant_type_info_element (GVariantTypeInfo *info)
300 return ARRAY_INFO (info)->element;
304 * g_variant_type_query_element:
305 * @info: a #GVariantTypeInfo for an array or maybe type
306 * @alignment: the location to store the alignment, or %NULL
307 * @fixed_size: the location to store the fixed size, or %NULL
309 * Returns the alignment requires and fixed size (if any) for the
310 * element type of the array. This call is a convenience wrapper around
311 * g_variant_type_info_element() and g_variant_type_info_query().
314 g_variant_type_info_query_element (GVariantTypeInfo *info,
318 g_variant_type_info_query (ARRAY_INFO (info)->element,
319 alignment, fixed_size);
323 #define TUPLE_INFO_CLASS 'r'
325 TUPLE_INFO (GVariantTypeInfo *info)
327 g_variant_type_info_check (info, TUPLE_INFO_CLASS);
329 return (TupleInfo *) info;
333 tuple_info_free (GVariantTypeInfo *info)
335 TupleInfo *tuple_info;
338 g_assert (info->container_class == TUPLE_INFO_CLASS);
339 tuple_info = (TupleInfo *) info;
341 for (i = 0; i < tuple_info->n_members; i++)
342 g_variant_type_info_unref (tuple_info->members[i].type_info);
344 g_slice_free1 (sizeof (GVariantMemberInfo) * tuple_info->n_members,
345 tuple_info->members);
346 g_slice_free (TupleInfo, tuple_info);
350 tuple_allocate_members (const GVariantType *type,
351 GVariantMemberInfo **members,
354 const GVariantType *item_type;
357 *n_members = g_variant_type_n_items (type);
358 *members = g_slice_alloc (sizeof (GVariantMemberInfo) * *n_members);
360 item_type = g_variant_type_first (type);
363 GVariantMemberInfo *member = &(*members)[i++];
365 member->type_info = g_variant_type_info_get (item_type);
366 item_type = g_variant_type_next (item_type);
368 if (member->type_info->fixed_size)
369 member->ending_type = G_VARIANT_MEMBER_ENDING_FIXED;
370 else if (item_type == NULL)
371 member->ending_type = G_VARIANT_MEMBER_ENDING_LAST;
373 member->ending_type = G_VARIANT_MEMBER_ENDING_OFFSET;
376 g_assert (i == *n_members);
379 /* this is g_variant_type_info_query for a given member of the tuple.
380 * before the access is done, it is ensured that the item is within
381 * range and %FALSE is returned if not.
384 tuple_get_item (TupleInfo *info,
385 GVariantMemberInfo *item,
389 if (&info->members[info->n_members] == item)
392 *d = item->type_info->alignment;
393 *e = item->type_info->fixed_size;
397 /* Read the documentation for #GVariantMemberInfo in gvarianttype.h
398 * before attempting to understand this.
400 * This function adds one set of "magic constant" values (for one item
401 * in the tuple) to the table.
403 * The algorithm in tuple_generate_table() calculates values of 'a', 'b'
404 * and 'c' for each item, such that the procedure for finding the item
405 * is to start at the end of the previous variable-sized item, add 'a',
406 * then round up to the nearest multiple of 'b', then then add 'c'.
407 * Note that 'b' is stored in the usual "one less than" form. ie:
409 * start = ROUND_UP(prev_end + a, (b + 1)) + c;
411 * We tweak these values a little to allow for a slightly easier
412 * computation and more compact storage.
415 tuple_table_append (GVariantMemberInfo **items,
421 GVariantMemberInfo *item = (*items)++;
423 /* We can shift multiples of the alignment size from 'c' into 'a'.
424 * As long as we're shifting whole multiples, it won't affect the
425 * result. This means that we can take the "aligned" portion off of
426 * 'c' and add it into 'a'.
428 * Imagine (for sake of clarity) that ROUND_10 rounds up to the
429 * nearest 10. It is clear that:
431 * ROUND_10(a) + c == ROUND_10(a + 10*(c / 10)) + (c % 10)
433 * ie: remove the 10s portion of 'c' and add it onto 'a'.
435 * To put some numbers on it, imagine we start with a = 34 and c = 27:
437 * ROUND_10(34) + 27 = 40 + 27 = 67
439 * but also, we can split 27 up into 20 and 7 and do this:
441 * ROUND_10(34 + 20) + 7 = ROUND_10(54) + 7 = 60 + 7 = 67
443 * without affecting the result. We do that here.
445 * This reduction in the size of 'c' means that we can store it in a
446 * gchar instead of a gsize. Due to how the structure is packed, this
447 * ends up saving us 'two pointer sizes' per item in each tuple when
448 * allocating using GSlice.
450 a += ~b & c; /* take the "aligned" part of 'c' and add to 'a' */
451 c &= b; /* chop 'c' to contain only the unaligned part */
454 /* Finally, we made one last adjustment. Recall:
456 * start = ROUND_UP(prev_end + a, (b + 1)) + c;
458 * Forgetting the '+ c' for the moment:
460 * ROUND_UP(prev_end + a, (b + 1));
462 * we can do a "round up" operation by adding 1 less than the amount
463 * to round up to, then rounding down. ie:
465 * #define ROUND_UP(x, y) ROUND_DOWN(x + (y-1), y)
467 * Of course, for rounding down to a power of two, we can just mask
468 * out the appropriate number of low order bits:
470 * #define ROUND_DOWN(x, y) (x & ~(y - 1))
474 * #define ROUND_UP(x, y) (x + (y - 1) & ~(y - 1))
476 * but recall that our alignment value 'b' is already "one less".
477 * This means that to round 'prev_end + a' up to 'b' we can just do:
479 * ((prev_end + a) + b) & ~b
481 * Associativity, and putting the 'c' back on:
483 * (prev_end + (a + b)) & ~b + c
485 * Now, since (a + b) is constant, we can just add 'b' to 'a' now and
486 * store that as the number to add to prev_end. Then we use ~b as the
487 * number to take a bitwise 'and' with. Finally, 'c' is added on.
489 * Note, however, that all the low order bits of the 'aligned' value
490 * are masked out and that all of the high order bits of 'c' have been
491 * "moved" to 'a' (in the previous step). This means that there are
492 * no overlapping bits in the addition -- so we can do a bitwise 'or'
495 * This means that we can now compute the start address of a given
496 * item in the tuple using the algorithm given in the documentation
497 * for #GVariantMemberInfo:
499 * item_start = ((prev_end + a) & b) | c;
509 tuple_align (gsize offset,
512 return offset + ((-offset) & alignment);
515 /* This function is the heart of the algorithm for calculating 'i', 'a',
516 * 'b' and 'c' for each item in the tuple.
518 * Imagine we want to find the start of the "i" in the type "(su(qx)ni)".
519 * That's a string followed by a uint32, then a tuple containing a
520 * uint16 and a int64, then an int16, then our "i". In order to get to
523 * Start at the end of the string, align to 4 (for the uint32), add 4.
524 * Align to 8, add 16 (for the tuple). Align to 2, add 2 (for the
525 * int16). Then we're there. It turns out that, given 3 simple rules,
526 * we can flatten this iteration into one addition, one alignment, then
529 * The loop below plays through each item in the tuple, querying its
530 * alignment and fixed_size into 'd' and 'e', respectively. At all
531 * times the variables 'a', 'b', and 'c' are maintained such that in
532 * order to get to the current point, you add 'a', align to 'b' then add
533 * 'c'. 'b' is kept in "one less than" form. For each item, the proper
534 * alignment is applied to find the values of 'a', 'b' and 'c' to get to
535 * the start of that item. Those values are recorded into the table.
536 * The fixed size of the item (if applicable) is then added on.
538 * These 3 rules are how 'a', 'b' and 'c' are modified for alignment and
539 * addition of fixed size. They have been proven correct but are
540 * presented here, without proof:
542 * 1) in order to "align to 'd'" where 'd' is less than or equal to the
543 * largest level of alignment seen so far ('b'), you align 'c' to
545 * 2) in order to "align to 'd'" where 'd' is greater than the largest
546 * level of alignment seen so far, you add 'c' aligned to 'b' to the
547 * value of 'a', set 'b' to 'd' (ie: increase the 'largest alignment
548 * seen') and reset 'c' to 0.
549 * 3) in order to "add 'e'", just add 'e' to 'c'.
552 tuple_generate_table (TupleInfo *info)
554 GVariantMemberInfo *items = info->members;
555 gsize i = -1, a = 0, b = 0, c = 0, d, e;
557 /* iterate over each item in the tuple.
558 * 'd' will be the alignment of the item (in one-less form)
559 * 'e' will be the fixed size (or 0 for variable-size items)
561 while (tuple_get_item (info, items, &d, &e))
565 c = tuple_align (c, d); /* rule 1 */
567 a += tuple_align (c, b), b = d, c = 0; /* rule 2 */
569 /* the start of the item is at this point (ie: right after we
570 * have aligned for it). store this information in the table.
572 tuple_table_append (&items, i, a, b, c);
574 /* "move past" the item by adding in its size. */
578 * we'll have an offset stored to mark the end of this item, so
579 * just bump the offset index to give us a new starting point
580 * and reset all the counters.
590 tuple_set_base_info (TupleInfo *info)
592 GVariantTypeInfo *base = &info->container.info;
594 if (info->n_members > 0)
596 GVariantMemberInfo *m;
598 /* the alignment requirement of the tuple is the alignment
599 * requirement of its largest item.
602 for (m = info->members; m < &info->members[info->n_members]; m++)
603 /* can find the max of a list of "one less than" powers of two
606 base->alignment |= m->type_info->alignment;
608 m--; /* take 'm' back to the last item */
610 /* the structure only has a fixed size if no variable-size
611 * offsets are stored and the last item is fixed-sized too (since
612 * an offset is never stored for the last item).
614 if (m->i == -1 && m->type_info->fixed_size)
615 /* in that case, the fixed size can be found by finding the
616 * start of the last item (in the usual way) and adding its
619 * if a tuple has a fixed size then it is always a multiple of
620 * the alignment requirement (to make packing into arrays
621 * easier) so we round up to that here.
624 tuple_align (((m->a & m->b) | m->c) + m->type_info->fixed_size,
627 /* else, the tuple is not fixed size */
628 base->fixed_size = 0;
632 /* the empty tuple: '()'.
634 * has a size of 1 and an no alignment requirement.
636 * It has a size of 1 (not 0) for two practical reasons:
638 * 1) So we can determine how many of them are in an array
639 * without dividing by zero or without other tricks.
641 * 2) Even if we had some trick to know the number of items in
642 * the array (as GVariant did at one time) this would open a
643 * potential denial of service attack: an attacker could send
644 * you an extremely small array (in terms of number of bytes)
645 * containing trillions of zero-sized items. If you iterated
646 * over this array you would effectively infinite-loop your
647 * program. By forcing a size of at least one, we bound the
648 * amount of computation done in response to a message to a
649 * reasonable function of the size of that message.
652 base->fixed_size = 1;
656 static ContainerInfo *
657 tuple_info_new (const GVariantType *type)
661 info = g_slice_new (TupleInfo);
662 info->container.info.container_class = TUPLE_INFO_CLASS;
664 tuple_allocate_members (type, &info->members, &info->n_members);
665 tuple_generate_table (info);
666 tuple_set_base_info (info);
668 return (ContainerInfo *) info;
672 * g_variant_type_info_n_members:
673 * @info: a #GVariantTypeInfo for a tuple or dictionary entry type
675 * Returns the number of members in a tuple or dictionary entry type.
676 * For a dictionary entry this will always be 2.
679 g_variant_type_info_n_members (GVariantTypeInfo *info)
681 return TUPLE_INFO (info)->n_members;
685 * g_variant_type_info_member_info:
686 * @info: a #GVariantTypeInfo for a tuple or dictionary entry type
687 * @index: the member to fetch information for
689 * Returns the #GVariantMemberInfo for a given member. See
690 * documentation for that structure for why you would want this
693 * @index must refer to a valid child (ie: strictly less than
694 * g_variant_type_info_n_members() returns).
696 const GVariantMemberInfo *
697 g_variant_type_info_member_info (GVariantTypeInfo *info,
700 TupleInfo *tuple_info = TUPLE_INFO (info);
702 if (index < tuple_info->n_members)
703 return &tuple_info->members[index];
708 /* == new/ref/unref == */
709 static GStaticRecMutex g_variant_type_info_lock = G_STATIC_REC_MUTEX_INIT;
710 static GHashTable *g_variant_type_info_table;
713 * g_variant_type_info_get:
714 * @type: a #GVariantType
716 * Returns a reference to a #GVariantTypeInfo for @type.
718 * If an info structure already exists for this type, a new reference is
719 * returned. If not, the required calculations are performed and a new
720 * info structure is returned.
722 * It is appropriate to call g_variant_type_info_unref() on the return
726 g_variant_type_info_get (const GVariantType *type)
730 type_char = g_variant_type_peek_string (type)[0];
732 if (type_char == G_VARIANT_TYPE_INFO_CHAR_MAYBE ||
733 type_char == G_VARIANT_TYPE_INFO_CHAR_ARRAY ||
734 type_char == G_VARIANT_TYPE_INFO_CHAR_TUPLE ||
735 type_char == G_VARIANT_TYPE_INFO_CHAR_DICT_ENTRY)
737 GVariantTypeInfo *info;
740 if G_UNLIKELY (g_variant_type_info_table == NULL)
741 g_variant_type_info_table = g_hash_table_new (g_str_hash,
744 type_string = g_variant_type_dup_string (type);
746 g_static_rec_mutex_lock (&g_variant_type_info_lock);
747 info = g_hash_table_lookup (g_variant_type_info_table, type_string);
751 ContainerInfo *container;
753 if (type_char == G_VARIANT_TYPE_INFO_CHAR_MAYBE ||
754 type_char == G_VARIANT_TYPE_INFO_CHAR_ARRAY)
756 container = array_info_new (type);
758 else /* tuple or dict entry */
760 container = tuple_info_new (type);
763 info = (GVariantTypeInfo *) container;
764 container->type_string = type_string;
765 container->ref_count = 1;
767 g_hash_table_insert (g_variant_type_info_table, type_string, info);
771 g_variant_type_info_ref (info);
773 g_static_rec_mutex_unlock (&g_variant_type_info_lock);
774 g_variant_type_info_check (info, 0);
775 g_free (type_string);
781 const GVariantTypeInfo *info;
784 index = type_char - 'b';
785 g_assert (G_N_ELEMENTS (g_variant_type_info_basic_table) == 24);
786 g_assert_cmpint (0, <=, index);
787 g_assert_cmpint (index, <, 24);
789 info = g_variant_type_info_basic_table + index;
790 g_variant_type_info_check (info, 0);
792 return (GVariantTypeInfo *) info;
797 * g_variant_type_info_ref:
798 * @info: a #GVariantTypeInfo
800 * Adds a reference to @info.
803 g_variant_type_info_ref (GVariantTypeInfo *info)
805 g_variant_type_info_check (info, 0);
807 if (info->container_class)
809 ContainerInfo *container = (ContainerInfo *) info;
811 g_assert_cmpint (container->ref_count, >, 0);
812 g_atomic_int_inc (&container->ref_count);
819 * g_variant_type_info_unref:
820 * @info: a #GVariantTypeInfo
822 * Releases a reference held on @info. This may result in @info being
826 g_variant_type_info_unref (GVariantTypeInfo *info)
828 g_variant_type_info_check (info, 0);
830 if (info->container_class)
832 ContainerInfo *container = (ContainerInfo *) info;
834 if (g_atomic_int_dec_and_test (&container->ref_count))
836 g_static_rec_mutex_lock (&g_variant_type_info_lock);
837 g_hash_table_remove (g_variant_type_info_table,
838 container->type_string);
839 if (g_hash_table_size (g_variant_type_info_table) == 0)
841 g_hash_table_unref (g_variant_type_info_table);
842 g_variant_type_info_table = NULL;
844 g_static_rec_mutex_unlock (&g_variant_type_info_lock);
846 g_free (container->type_string);
848 if (info->container_class == ARRAY_INFO_CLASS)
849 array_info_free (info);
851 else if (info->container_class == TUPLE_INFO_CLASS)
852 tuple_info_free (info);
855 g_assert_not_reached ();
860 /* used from the test cases */
861 #define assert_no_type_infos() \
862 g_assert (g_variant_type_info_table == NULL)