--- /dev/null
+/*
+ * 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 ();
+ }
+ }
+}
--- /dev/null
+/*
+ * 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__ */
}
/* 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);
{
GVariantType *result;
- switch (g_test_rand_int_range (0, 7))
+ switch (g_test_rand_int_range (0, definite ? 5 : 7))
{
case 0:
{
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);
}
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);
}
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;
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);
}
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;
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, ", ");
/* 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 ();
*
* 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
/* 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);
}
}
+#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 ();
}
projects / platform / upstream / glib.git / commitdiff