[glib/new-gsettings] GIO: Add gvdb as private API
- From: Ryan Lortie <ryanl src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [glib/new-gsettings] GIO: Add gvdb as private API
- Date: Tue, 13 Apr 2010 19:39:56 +0000 (UTC)
commit 8c65bbf1a383a4bad9c776e92cc1c77369506438
Author: Ryan Lortie <desrt desrt ca>
Date: Tue Apr 13 13:13:54 2010 -0400
GIO: Add gvdb as private API
gio/Makefile.am | 6 +
gio/gvdb/gvdb-builder.c | 501 +++++++++++++++++++++++++++++++++++++++++++++++
gio/gvdb/gvdb-builder.h | 57 ++++++
gio/gvdb/gvdb-format.h | 61 ++++++
gio/gvdb/gvdb-reader.c | 464 +++++++++++++++++++++++++++++++++++++++++++
gio/gvdb/gvdb-reader.h | 47 +++++
6 files changed, 1136 insertions(+), 0 deletions(-)
---
diff --git a/gio/Makefile.am b/gio/Makefile.am
index 29e7327..00107f5 100644
--- a/gio/Makefile.am
+++ b/gio/Makefile.am
@@ -79,6 +79,11 @@ gio-marshal.c: gio-marshal.h gio-marshal.list
$(glib_genmarshal) --prefix=_gio_marshal $(srcdir)/gio-marshal.list --body --internal) > $ tmp && \
mv $ tmp $@
+settings_sources = \
+ gvdb/gvdb-format.h \
+ gvdb/gvdb-reader.h \
+ gvdb/gvdb-reader.c
+
local_sources = \
glocaldirectorymonitor.c \
glocaldirectorymonitor.h \
@@ -289,6 +294,7 @@ libgio_2_0_la_SOURCES = \
$(unix_sources) \
$(win32_sources) \
$(local_sources) \
+ $(settings_sources) \
$(marshal_sources) \
$(NULL)
diff --git a/gio/gvdb/gvdb-builder.c b/gio/gvdb/gvdb-builder.c
new file mode 100644
index 0000000..56a679e
--- /dev/null
+++ b/gio/gvdb/gvdb-builder.c
@@ -0,0 +1,501 @@
+#include "gvdb-builder.h"
+
+#include <glib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "gvdb.h"
+
+struct _GvdbItem
+{
+ gchar *key;
+ guint32 hash_value;
+ guint32_le assigned_index;
+ GvdbItem *parent;
+ GvdbItem *sibling;
+ GvdbItem *next;
+ GVariant *options;
+
+ /* one of:
+ * this:
+ */
+ GVariant *value;
+
+ /* this: */
+ GHashTable *table;
+
+ /* or this: */
+ GvdbItem *child;
+};
+
+static void
+gvdb_item_free (gpointer data)
+{
+ GvdbItem *item = data;
+
+ g_free (item->key);
+
+ if (item->value)
+ g_variant_unref (item->value);
+
+ if (item->options)
+ g_variant_unref (item->options);
+
+ if (item->table)
+ g_hash_table_unref (item->table);
+
+ g_slice_free (GvdbItem, item);
+}
+
+GHashTable *
+gvdb_hash_table_new (GHashTable *parent,
+ const gchar *name_in_parent)
+{
+ GHashTable *table;
+
+ table = g_hash_table_new_full (g_str_hash, g_str_equal,
+ g_free, gvdb_item_free);
+
+ if (parent)
+ {
+ GvdbItem *item;
+
+ item = gvdb_hash_table_insert (parent, name_in_parent);
+ gvdb_item_set_hash_table (item, table);
+ }
+
+ return table;
+}
+
+static guint32
+djb_hash (const gchar *key)
+{
+ guint32 hash_value = 5381;
+
+ while (*key)
+ hash_value = hash_value * 33 + *key++;
+
+ return hash_value;
+}
+
+GvdbItem *
+gvdb_hash_table_insert (GHashTable *table,
+ const gchar *key)
+{
+ GvdbItem *item;
+
+ item = g_slice_new0 (GvdbItem);
+ item->key = g_strdup (key);
+ item->hash_value = djb_hash (key);
+
+ g_hash_table_insert (table, g_strdup (key), item);
+
+ return item;
+}
+
+void
+gvdb_hash_table_insert_string (GHashTable *table,
+ const gchar *key,
+ const gchar *value)
+{
+ GvdbItem *item;
+
+ item = gvdb_hash_table_insert (table, key);
+ gvdb_item_set_value (item, g_variant_new_string (value));
+}
+
+void
+gvdb_item_set_value (GvdbItem *item,
+ GVariant *value)
+{
+ g_return_if_fail (!item->value && !item->table && !item->child);
+
+ item->value = g_variant_ref_sink (value);
+}
+
+void
+gvdb_item_set_options (GvdbItem *item,
+ GVariant *options)
+{
+ g_return_if_fail (!item->options);
+
+ item->options = g_variant_ref_sink (options);
+}
+
+void
+gvdb_item_set_hash_table (GvdbItem *item,
+ GHashTable *table)
+{
+ g_return_if_fail (!item->value && !item->table && !item->child);
+
+ item->table = g_hash_table_ref (table);
+}
+
+void
+gvdb_item_set_parent (GvdbItem *item,
+ GvdbItem *parent)
+{
+ GvdbItem **node;
+
+ g_return_if_fail (g_str_has_prefix (item->key, parent->key));
+ g_return_if_fail (!parent->value && !parent->table);
+ g_return_if_fail (!item->parent && !item->sibling);
+
+ for (node = &parent->child; *node; node = &(*node)->sibling)
+ if (strcmp ((*node)->key, item->key) > 0)
+ break;
+
+ item->parent = parent;
+ item->sibling = *node;
+ *node = item;
+}
+
+
+
+
+typedef struct
+{
+ GvdbItem **buckets;
+ gint n_buckets;
+} HashTable;
+
+HashTable *
+hash_table_new (gint n_buckets)
+{
+ HashTable *table;
+
+ table = g_slice_new (HashTable);
+ table->buckets = g_new0 (GvdbItem *, n_buckets);
+ table->n_buckets = n_buckets;
+
+ return table;
+}
+
+static void
+hash_table_insert (gpointer key,
+ gpointer value,
+ gpointer data)
+{
+ guint32 hash_value, bucket;
+ HashTable *table = data;
+ GvdbItem *item = value;
+
+g_print ("i see %s\n", (char*) key);
+
+ hash_value = djb_hash (key);
+ bucket = hash_value % table->n_buckets;
+ item->next = table->buckets[bucket];
+ table->buckets[bucket] = item;
+}
+
+static guint32_le
+item_to_index (GvdbItem *item)
+{
+ if (item != NULL)
+ return item->assigned_index;
+
+ return guint32_to_le (-1u);
+}
+
+typedef struct
+{
+ GString *strings;
+ GQueue *chunks;
+ guint64 offset;
+
+} FileBuilder;
+
+typedef struct
+{
+ gsize offset;
+ gsize size;
+ gpointer data;
+} FileChunk;
+
+static gpointer
+file_builder_allocate (FileBuilder *fb,
+ guint alignment,
+ gsize size,
+ struct gvdb_pointer *pointer)
+{
+ FileChunk *chunk;
+
+ fb->offset += (-fb->offset) & (alignment - 1);
+ chunk = g_slice_new (FileChunk);
+ chunk->offset = fb->offset;
+ chunk->size = size;
+ chunk->data = g_malloc (size);
+
+ pointer->start = guint32_to_le (fb->offset);
+ fb->offset += size;
+ pointer->end = guint32_to_le (fb->offset);
+
+ g_queue_push_tail (fb->chunks, chunk);
+
+ return chunk->data;
+}
+
+static void
+file_builder_add_value (FileBuilder *fb,
+ GVariant *value,
+ struct gvdb_pointer *pointer)
+{
+ GVariant *variant, *normal;
+ gpointer data;
+ gsize size;
+
+ variant = g_variant_new_variant (value);
+ normal = g_variant_get_normal_form (variant);
+ g_variant_unref (variant);
+
+ size = g_variant_get_size (normal);
+ data = file_builder_allocate (fb, 8, size, pointer);
+ g_variant_store (normal, data);
+ g_variant_unref (normal);
+}
+
+static void
+file_builder_add_options (FileBuilder *fb,
+ GVariant *options,
+ struct gvdb_pointer *pointer)
+{
+ GVariant *normal;
+ gpointer data;
+ gsize size;
+
+ if (options != NULL)
+ {
+ normal = g_variant_get_normal_form (options);
+ size = g_variant_get_size (normal);
+ data = file_builder_allocate (fb, 8, size, pointer);
+ g_variant_store (normal, data);
+ g_variant_unref (normal);
+ }
+ else
+ {
+ pointer->start = guint32_to_le (0);
+ pointer->end = guint32_to_le (0);
+ }
+}
+
+static void
+file_builder_add_string (FileBuilder *fb,
+ const gchar *string,
+ guint32_le *start,
+ guint16_le *size)
+{
+ FileChunk *chunk;
+ gsize length;
+
+ length = strlen (string);
+
+ chunk = g_slice_new (FileChunk);
+ chunk->offset = fb->offset;
+ chunk->size = length;
+ chunk->data = g_malloc (length);
+ memcpy (chunk->data, string, length);
+
+ *start = guint32_to_le (fb->offset);
+ *size = guint16_to_le (length);
+ fb->offset += length;
+
+ g_queue_push_tail (fb->chunks, chunk);
+}
+
+static void
+file_builder_allocate_for_hash (FileBuilder *fb,
+ gsize n_buckets,
+ gsize n_items,
+ guint bloom_shift,
+ gsize n_bloom_words,
+ guint32_le **bloom_filter,
+ guint32_le **hash_buckets,
+ struct gvdb_hash_item **hash_items,
+ struct gvdb_pointer *pointer)
+{
+ guint32_le bloom_hdr, table_hdr;
+ guchar *data;
+ gsize size;
+
+ g_assert (n_bloom_words < (1u << 27));
+
+ bloom_hdr = guint32_to_le (bloom_shift << 27 | n_bloom_words);
+ table_hdr = guint32_to_le (n_buckets);
+
+ size = sizeof bloom_hdr + sizeof table_hdr +
+ n_bloom_words * sizeof (guint32_le) +
+ n_buckets * sizeof (guint32_le) +
+ n_items * sizeof (struct gvdb_hash_item);
+
+ data = file_builder_allocate (fb, 4, size, pointer);
+
+#define chunk(s) (size -= (s), data += (s), data - (s))
+ memcpy (chunk (sizeof bloom_hdr), &bloom_hdr, sizeof bloom_hdr);
+ memcpy (chunk (sizeof table_hdr), &table_hdr, sizeof table_hdr);
+ *bloom_filter = (guint32_le *) chunk (n_bloom_words * sizeof (guint32_le));
+ *hash_buckets = (guint32_le *) chunk (n_buckets * sizeof (guint32_le));
+ *hash_items = (struct gvdb_hash_item *) chunk (n_items *
+ sizeof (struct gvdb_hash_item));
+ g_assert (size == 0);
+#undef chunk
+
+ memset (*bloom_filter, 0, n_bloom_words * sizeof (guint32_le));
+}
+
+static void
+file_builder_add_hash (FileBuilder *fb,
+ GHashTable *table,
+ struct gvdb_pointer *pointer)
+{
+ guint32_le *buckets, *bloom_filter;
+ struct gvdb_hash_item *items;
+ HashTable *mytable;
+ GvdbItem *item;
+ guint32 index;
+ gint bucket;
+
+ mytable = hash_table_new (g_hash_table_size (table));
+ g_hash_table_foreach (table, hash_table_insert, mytable);
+ index = 0;
+
+ for (bucket = 0; bucket < mytable->n_buckets; bucket++)
+ for (item = mytable->buckets[bucket]; item; item = item->next)
+ item->assigned_index = guint32_to_le (index++);
+
+ file_builder_allocate_for_hash (fb, mytable->n_buckets, index, 5, 0,
+ &bloom_filter, &buckets, &items, pointer);
+
+ for (bucket = 0; bucket < mytable->n_buckets; bucket++)
+ {
+ buckets[bucket] = item_to_index (mytable->buckets[bucket]);
+
+ for (item = mytable->buckets[bucket]; item; item = item->next)
+ {
+ struct gvdb_hash_item *entry = items++;
+ const gchar *basename;
+
+ entry->hash_value = guint32_to_le (item->hash_value);
+ entry->parent = item_to_index (item->parent);
+ entry->unused = 0;
+
+ if (item->parent != NULL)
+ basename = item->key + strlen (item->parent->key);
+ else
+ basename = item->key;
+
+ file_builder_add_string (fb, basename,
+ &entry->key_start,
+ &entry->key_size);
+
+ if (item->value != NULL)
+ {
+ g_assert (item->child == NULL && item->table == NULL);
+
+ file_builder_add_value (fb, item->value, &entry->value.pointer);
+ file_builder_add_options (fb, item->options, &entry->options);
+ entry->type = 'v';
+ }
+
+ if (item->child != NULL)
+ {
+ guint32 children = 0;
+ guint32_le *offsets;
+ GvdbItem *child;
+
+ g_assert (item->table == NULL);
+
+ for (child = item->child; child; child = child->sibling)
+ children++;
+
+ offsets = file_builder_allocate (fb, 4, 4 * children,
+ &entry->value.pointer);
+ entry->type = 'L';
+
+ for (child = item->child; child; child = child->sibling)
+ offsets[--children] = child->assigned_index;
+
+ g_assert (children == 0);
+ }
+
+ if (item->table != NULL)
+ {
+ entry->type = 'H';
+ file_builder_add_hash (fb, item->table, &entry->value.pointer);
+ }
+ }
+ }
+}
+
+static FileBuilder *
+file_builder_new (void)
+{
+ FileBuilder *builder;
+
+ builder = g_slice_new (FileBuilder);
+ builder->strings = g_string_new ("");
+ builder->chunks = g_queue_new ();
+ builder->offset = sizeof (struct gvdb_header);
+
+ return builder;
+}
+
+static gboolean
+file_builder_write (FileBuilder *fb,
+ GOutputStream *output,
+ struct gvdb_pointer root,
+ GError **error)
+{
+ struct gvdb_header header = { { GVDB_SIGNATURE0, GVDB_SIGNATURE1 } };
+ gchar zero[8] = { 0, };
+ gsize offset;
+
+ header.root = root;
+ if (!g_output_stream_write_all (output, &header, sizeof header,
+ NULL, NULL, error))
+ return FALSE;
+
+ offset = sizeof header;
+ while (!g_queue_is_empty (fb->chunks))
+ {
+ FileChunk *chunk = g_queue_pop_head (fb->chunks);
+
+ if (chunk->offset != offset)
+ {
+ g_assert (chunk->offset > offset);
+ g_assert (chunk->offset - offset < 8);
+
+ if (!g_output_stream_write_all (output, zero,
+ chunk->offset - offset,
+ NULL, NULL, error))
+ return FALSE;
+
+ offset = chunk->offset;
+ }
+
+ if (!g_output_stream_write_all (output, chunk->data, chunk->size,
+ NULL, NULL, error))
+ return FALSE;
+
+ offset += chunk->size;
+ g_free (chunk->data);
+ }
+
+ g_queue_free (fb->chunks);
+ g_slice_free (FileBuilder, fb);
+
+ return TRUE;
+}
+
+gboolean
+gvdb_file_write (GOutputStream *output,
+ GHashTable *table,
+ GError **error)
+{
+ struct gvdb_pointer root;
+ FileBuilder *fb;
+
+ fb = file_builder_new ();
+ file_builder_add_hash (fb, table, &root);
+ return file_builder_write (fb, output, root, error);
+}
diff --git a/gio/gvdb/gvdb-builder.h b/gio/gvdb/gvdb-builder.h
new file mode 100644
index 0000000..98d0c4a
--- /dev/null
+++ b/gio/gvdb/gvdb-builder.h
@@ -0,0 +1,57 @@
+/*
+ * 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 licence, 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.
+ */
+
+#ifndef __gvdb_builder_h__
+#define __gvdb_builder_h__
+
+#include <gio/gio.h>
+
+typedef struct _GvdbItem GvdbItem;
+
+G_GNUC_INTERNAL
+GHashTable * gvdb_hash_table_new (GHashTable *parent,
+ const gchar *key);
+
+G_GNUC_INTERNAL
+GvdbItem * gvdb_hash_table_insert (GHashTable *table,
+ const gchar *key);
+G_GNUC_INTERNAL
+void gvdb_hash_table_insert_string (GHashTable *table,
+ const gchar *key,
+ const gchar *value);
+
+G_GNUC_INTERNAL
+void gvdb_item_set_value (GvdbItem *item,
+ GVariant *value);
+G_GNUC_INTERNAL
+void gvdb_item_set_options (GvdbItem *item,
+ GVariant *options);
+G_GNUC_INTERNAL
+void gvdb_item_set_hash_table (GvdbItem *item,
+ GHashTable *table);
+G_GNUC_INTERNAL
+void gvdb_item_set_parent (GvdbItem *item,
+ GvdbItem *parent);
+
+G_GNUC_INTERNAL
+gboolean gvdb_file_write (GOutputStream *output,
+ GHashTable *table,
+ GError **error);
+
+#endif /* __gvdb_builder_h__ */
diff --git a/gio/gvdb/gvdb-format.h b/gio/gvdb/gvdb-format.h
new file mode 100644
index 0000000..73d15b7
--- /dev/null
+++ b/gio/gvdb/gvdb-format.h
@@ -0,0 +1,61 @@
+#include <glib.h>
+
+typedef struct { guint16 __value; } guint16_le;
+typedef struct { guint32 __value; } guint32_le;
+
+struct gvdb_pointer {
+ guint32_le start;
+ guint32_le end;
+};
+
+struct gvdb_hash_header {
+ guint32_le n_bloom_words;
+ guint32_le n_buckets;
+};
+
+struct gvdb_hash_item {
+ guint32_le hash_value;
+ guint32_le parent;
+
+ guint32_le key_start;
+ guint16_le key_size;
+ gchar type;
+ gchar unused;
+
+ union
+ {
+ struct gvdb_pointer pointer;
+ gchar direct[8];
+ } value;
+
+ struct gvdb_pointer options;
+};
+
+struct gvdb_header {
+ guint32 signature[2];
+ guint32_le version;
+ guint32_le options;
+
+ struct gvdb_pointer root;
+};
+
+static inline guint32_le guint32_to_le (guint32 value) {
+ guint32_le result = { GUINT32_TO_LE (value) };
+ return result;
+}
+
+static inline guint32 guint32_from_le (guint32_le value) {
+ return GUINT32_FROM_LE (value.__value);
+}
+
+static inline guint16_le guint16_to_le (guint16 value) {
+ guint16_le result = { GUINT16_TO_LE (value) };
+ return result;
+}
+
+static inline guint16 guint16_from_le (guint16_le value) {
+ return GUINT16_FROM_LE (value.__value);
+}
+
+#define GVDB_SIGNATURE0 1918981703
+#define GVDB_SIGNATURE1 1953390953
diff --git a/gio/gvdb/gvdb-reader.c b/gio/gvdb/gvdb-reader.c
new file mode 100644
index 0000000..37f9cc1
--- /dev/null
+++ b/gio/gvdb/gvdb-reader.c
@@ -0,0 +1,464 @@
+/*
+ * 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 licence, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "gvdb-reader.h"
+#include "gvdb-format.h"
+
+#include <string.h>
+
+struct _GvdbTable {
+ gint ref_count;
+
+ const gchar *data;
+ gsize size;
+
+ GMappedFile *mapped;
+ gboolean trusted;
+
+ const guint32 *bloom_words;
+ guint32 n_bloom_words;
+ guint bloom_shift;
+
+ const guint32 *hash_buckets;
+ guint32 n_buckets;
+
+ struct gvdb_hash_item *hash_items;
+ guint32 n_hash_items;
+};
+
+static const gchar *
+gvdb_table_item_get_key (GvdbTable *file,
+ const struct gvdb_hash_item *item,
+ gsize *size)
+{
+ guint32 start, end;
+
+ start = guint32_from_le (item->key_start);
+ *size = guint16_from_le (item->key_size);
+ end = start + *size;
+
+ if G_UNLIKELY (start > end || end > file->size)
+ return NULL;
+
+ return file->data + start;
+}
+
+static gconstpointer
+gvdb_table_dereference (GvdbTable *file,
+ const struct gvdb_pointer *pointer,
+ gint alignment,
+ gsize *size)
+{
+ guint32 start, end;
+
+ start = guint32_from_le (pointer->start);
+ end = guint32_from_le (pointer->end);
+
+ if G_UNLIKELY (start > end || end > file->size || start & (alignment - 1))
+ return NULL;
+
+ *size = end - start;
+
+ return file->data + start;
+}
+
+static void
+gvdb_table_setup_root (GvdbTable *file,
+ const struct gvdb_pointer *pointer)
+{
+ const struct gvdb_hash_header *header;
+ guint32 n_bloom_words;
+ guint32 bloom_shift;
+ guint32 n_buckets;
+ gsize size;
+
+ header = gvdb_table_dereference (file, pointer, 4, &size);
+
+ if G_UNLIKELY (header == NULL || size < sizeof *header)
+ return;
+
+ size -= sizeof *header;
+
+ n_bloom_words = guint32_from_le (header->n_bloom_words);
+ n_buckets = guint32_from_le (header->n_buckets);
+ bloom_shift = n_bloom_words >> 27;
+ n_bloom_words &= (1u << 27) - 1;
+
+ if G_UNLIKELY (n_bloom_words * sizeof (guint32_le) > size)
+ return;
+
+ file->bloom_words = (gpointer) (header + 1);
+ size -= n_bloom_words * sizeof (guint32_le);
+ file->n_bloom_words = n_bloom_words;
+
+ if G_UNLIKELY (n_buckets > G_MAXUINT / sizeof (guint32_le) ||
+ n_buckets * sizeof (guint32_le) > size)
+ return;
+
+ file->hash_buckets = file->bloom_words + file->n_bloom_words;
+ size -= n_buckets * sizeof (guint32_le);
+ file->n_buckets = n_buckets;
+
+ if G_UNLIKELY (size % sizeof (struct gvdb_hash_item))
+ return;
+
+ file->hash_items = (gpointer) (file->hash_buckets + n_buckets);
+ file->n_hash_items = size / sizeof (struct gvdb_hash_item);
+}
+
+/**
+ * gvdb_table_new:
+ * @filename: the path to the hash file
+ * @trusted: if the contents of @filename are trusted
+ * @error: %NULL, or a pointer to a %NULL #GError
+ * @returns: a new #GvdbTable
+ *
+ * Creates a new #GvdbTable from the contents of the file found at
+ * @filename.
+ *
+ * The only time this function fails is if the file can not be opened.
+ * In that case, the #GError that is returned will be an error from
+ * g_mapped_file_new().
+ *
+ * An empty or otherwise corrupted file is considered to be a valid
+ * #GvdbTable with no entries.
+ *
+ * You should call gvdb_table_unref() on the return result when you no
+ * longer require it.
+ **/
+GvdbTable *
+gvdb_table_new (const gchar *filename,
+ gboolean trusted,
+ GError **error)
+{
+ GMappedFile *mapped;
+ GvdbTable *file;
+
+ if ((mapped = g_mapped_file_new (filename, FALSE, error)) == NULL)
+ return NULL;
+
+ file = g_slice_new0 (GvdbTable);
+ file->data = g_mapped_file_get_contents (mapped);
+ file->size = g_mapped_file_get_length (mapped);
+ file->trusted = trusted;
+ file->mapped = mapped;
+ file->ref_count = 1;
+
+ if (sizeof (struct gvdb_header) <= file->size)
+ {
+ const struct gvdb_header *header = (gpointer) file->data;
+ gvdb_table_setup_root (file, &header->root);
+ }
+
+ return file;
+}
+
+static gboolean
+gvdb_table_bloom_filter (GvdbTable *file,
+ guint32 hash_value)
+{
+ guint32 word, mask;
+
+ if (file->n_bloom_words == 0)
+ return TRUE;
+
+ word = (hash_value / 32) % file->n_bloom_words;
+ mask = 1 << (hash_value & 31);
+ mask |= 1 << ((hash_value >> file->bloom_shift) & 31);
+
+ return (file->bloom_words[word] & mask) == mask;
+}
+
+static gboolean
+gvdb_table_check_name (GvdbTable *file,
+ struct gvdb_hash_item *item,
+ const gchar *key,
+ guint key_length)
+{
+ const gchar *this_key;
+ gsize this_size;
+ guint32 parent;
+
+ this_key = gvdb_table_item_get_key (file, item, &this_size);
+
+ if G_UNLIKELY (this_key == NULL || this_size > key_length)
+ return FALSE;
+
+ key_length -= this_size;
+
+ if G_UNLIKELY (memcmp (this_key, key + key_length, this_size) != 0)
+ return FALSE;
+
+ parent = guint32_from_le (item->parent);
+ if (key_length == 0 && parent == -1)
+ return TRUE;
+
+ if G_LIKELY (parent < file->n_hash_items && this_size > 0)
+ return gvdb_table_check_name (file,
+ &file->hash_items[parent],
+ key, key_length);
+
+ return FALSE;
+}
+
+const struct gvdb_hash_item *
+gvdb_table_lookup (GvdbTable *file,
+ const gchar *key,
+ gchar type)
+{
+ guint32 hash_value = 5381;
+ guint key_length;
+ guint32 itemno;
+
+ if G_UNLIKELY (file->n_buckets == 0 || file->n_hash_items == 0)
+ return NULL;
+
+ for (key_length = 0; key[key_length]; key_length++)
+ hash_value = (hash_value * 33) + key[key_length];
+
+ if (!gvdb_table_bloom_filter (file, hash_value))
+ return NULL;
+
+ itemno = file->hash_buckets[hash_value % file->n_buckets];
+ hash_value &= ~(1u << 31);
+
+ while G_LIKELY (itemno < file->n_hash_items)
+ {
+ struct gvdb_hash_item *item = &file->hash_items[itemno];
+
+ if (hash_value == (guint32_from_le (item->hash_value) & ~(1u << 31)))
+ if G_LIKELY (gvdb_table_check_name (file, item, key, key_length))
+ if G_LIKELY (item->type == type)
+ return item;
+
+ if (guint32_from_le (item->hash_value) & (1u << 31))
+ return NULL;
+
+ itemno++;
+ }
+
+ return NULL;
+}
+
+/**
+ * gvdb_table_list:
+ * @file: a #GvdbTable
+ * @key: a string
+ * @returns: a %NULL-terminated string array
+ *
+ * List all of the keys that appear below @key. The nesting of keys
+ * within the hash file is defined by the program that created the hash
+ * file. One thing is constant: each item in the returned array can be
+ * concatenated to @key to obtain the full name of that key.
+ *
+ * It is not possible to tell from this function if a given key is
+ * itself a path, a value, or another hash table; you are expected to
+ * know this for yourself.
+ *
+ * You should call g_strfreev() on the return result when you no longer
+ * require it.
+ **/
+gchar **
+gvdb_table_list (GvdbTable *file,
+ const gchar *key)
+{
+ const struct gvdb_hash_item *item;
+ const guint32_le *list;
+ gchar **strv;
+ gsize size;
+ gint i;
+
+ if ((item = gvdb_table_lookup (file, key, 'L')) == NULL)
+ return NULL;
+
+ list = gvdb_table_dereference (file, &item->value.pointer, 4, &size);
+
+ if G_UNLIKELY (list == NULL || size % 4)
+ return NULL;
+
+ size /= 4;
+
+ strv = g_new (gchar *, size + 1);
+ for (i = 0; i < size; i++)
+ {
+ guint32 itemno = guint32_from_le (list[i]);
+
+ if (itemno < file->n_hash_items)
+ {
+ const struct gvdb_hash_item *item;
+ const gchar *string;
+ gsize strsize;
+
+ item = file->hash_items + itemno;
+
+ string = gvdb_table_item_get_key (file, item, &strsize);
+
+ if (string != NULL)
+ strv[i] = g_strndup (string, strsize);
+ else
+ strv[i] = g_malloc0 (1);
+ }
+ else
+ strv[i] = g_malloc0 (1);
+ }
+
+ strv[i] = NULL;
+
+ return strv;
+}
+
+/**
+ * gvdb_table_get_value:
+ * @file: a #GvdbTable
+ * @key: a string
+ * @options: a pointer to a #GVariant, or %NULL
+ * @returns: a #GVariant, or %NULL
+ *
+ * Looks up a value named @key in @file.
+ *
+ * If the value is not found then %NULL is returned. Otherwise, a new
+ * #GVariant instance is returned. The #GVariant does not depend on the
+ * continued existence of @file.
+ *
+ * If @options is non-%NULL then it will be set either to %NULL in the
+ * case of no options or a #GVariant containing a dictionary mapping
+ * strings to variants.
+ *
+ * You should call g_variant_unref() on the return result when you no
+ * longer require it.
+ **/
+GVariant *
+gvdb_table_get_value (GvdbTable *file,
+ const gchar *key,
+ GVariant **options)
+{
+ const struct gvdb_hash_item *item;
+ GVariant *variant, *value;
+ gconstpointer data;
+ gsize size;
+
+ if ((item = gvdb_table_lookup (file, key, 'v')) == NULL)
+ return NULL;
+
+ data = gvdb_table_dereference (file, &item->value.pointer, 8, &size);
+
+ if G_UNLIKELY (data == NULL)
+ return NULL;
+
+ variant = g_variant_new_from_data (G_VARIANT_TYPE_VARIANT,
+ data, size, file->trusted,
+ (GDestroyNotify) g_mapped_file_unref,
+ g_mapped_file_ref (file->mapped));
+ value = g_variant_get_variant (variant);
+ g_variant_unref (variant);
+
+ if (options != NULL)
+ {
+ data = gvdb_table_dereference (file, &item->options, 8, &size);
+
+ if (data != NULL || size > 0)
+ {
+ *options = g_variant_new_from_data (G_VARIANT_TYPE ("a{sv}"),
+ data, size, file->trusted,
+ (GDestroyNotify) g_mapped_file_unref,
+ g_mapped_file_ref (file->mapped));
+ g_variant_ref_sink (*options);
+ }
+ else
+ *options = NULL;
+ }
+
+ return value;
+}
+
+/**
+ * gvdb_table_get_hash:
+ * @file: a #GvdbTable
+ * @key: a string
+ * @returns: a new #GvdbTable, or %NULL
+ *
+ * Looks up the hash table named @key in @file.
+ *
+ * The toplevel hash table in a #GvdbTable can contain reference to
+ * child hash tables (and those can contain further references...).
+ *
+ * If @key is not found in @file then %NULL is returned. Otherwise, a
+ * new #GvdbTable is returned, referring to the child hashtable as
+ * contained in the file. This newly-created #GvdbTable does not depend
+ * on the continued existence of @file.
+ *
+ * You should call gvdb_table_unref() on the return result when you no
+ * longer require it.
+ **/
+GvdbTable *
+gvdb_table_get_hash (GvdbTable *file,
+ const gchar *key)
+{
+ const struct gvdb_hash_item *item;
+ GvdbTable *new;
+
+ item = gvdb_table_lookup (file, key, 'H');
+
+ if (item == NULL)
+ return NULL;
+
+ new = g_slice_new0 (GvdbTable);
+ new->mapped = g_mapped_file_ref (file->mapped);
+ new->trusted = file->trusted;
+ new->data = file->data;
+ new->size = file->size;
+ new->ref_count = 1;
+
+ gvdb_table_setup_root (new, &item->value.pointer);
+
+ return new;
+}
+
+/**
+ * gvdb_table_ref:
+ * @file: a #GvdbTable
+ * @returns: a new reference on @file
+ *
+ * Increases the reference count on @file.
+ **/
+GvdbTable *
+gvdb_table_ref (GvdbTable *file)
+{
+ g_atomic_int_inc (&file->ref_count);
+
+ return file;
+}
+
+/**
+ * gvdb_table_unref:
+ * @file: a #GvdbTable
+ *
+ * Decreases the reference count on @file, possibly freeing it.
+ *
+ * Since: 2.26
+ **/
+void
+gvdb_table_unref (GvdbTable *file)
+{
+ if (g_atomic_int_dec_and_test (&file->ref_count))
+ {
+ g_mapped_file_unref (file->mapped);
+ g_slice_free (GvdbTable, file);
+ }
+}
diff --git a/gio/gvdb/gvdb-reader.h b/gio/gvdb/gvdb-reader.h
new file mode 100644
index 0000000..fe63e55
--- /dev/null
+++ b/gio/gvdb/gvdb-reader.h
@@ -0,0 +1,47 @@
+/*
+ * 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 licence, 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.
+ */
+
+#ifndef __gvdb_reader_h__
+#define __gvdb_reader_h__
+
+#include <glib.h>
+
+typedef struct _GvdbTable GvdbTable;
+
+G_GNUC_INTERNAL
+GvdbTable * gvdb_table_new (const gchar *filename,
+ gboolean trusted,
+ GError **error);
+G_GNUC_INTERNAL
+GvdbTable * gvdb_table_ref (GvdbTable *table);
+G_GNUC_INTERNAL
+void gvdb_table_unref (GvdbTable *table);
+
+G_GNUC_INTERNAL
+gchar ** gvdb_table_list (GvdbTable *table,
+ const gchar *key);
+G_GNUC_INTERNAL
+GvdbTable * gvdb_table_get_table (GvdbTable *table,
+ const gchar *key);
+G_GNUC_INTERNAL
+GVariant * gvdb_table_get_value (GvdbTable *table,
+ const gchar *key,
+ GVariant **options);
+
+#endif /* __gvdb_reader_h__ */
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