glib/gvdb-builder.c

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/*
* 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 2.1 of the License, or (at your option) any later version.
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*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
#include "gvdb-builder.h"
#include "gvdb-format.h"
#include <glib.h>
#include <fcntl.h>
#if !defined(G_OS_WIN32) || !defined(_MSC_VER)
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#include <unistd.h>
#endif
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#include <string.h>
struct _GvdbItem
{
gchar *key;
guint32 hash_value;
guint32_le assigned_index;
GvdbItem *parent;
GvdbItem *sibling;
GvdbItem *next;
/* 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->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 + *(signed char *)key++;
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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_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;
static HashTable *
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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;
}
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static void
hash_table_free (HashTable *table)
{
g_free (table->buckets);
g_slice_free (HashTable, table);
}
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static void
hash_table_insert (gpointer key,
gpointer value,
gpointer data)
{
guint32 hash_value, bucket;
HashTable *table = data;
GvdbItem *item = value;
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
{
GQueue *chunks;
guint64 offset;
gboolean byteswap;
} 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;
if (size == 0)
return NULL;
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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,
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struct gvdb_pointer *pointer)
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{
GVariant *variant, *normal;
gpointer data;
gsize size;
if (fb->byteswap)
{
value = g_variant_byteswap (value);
variant = g_variant_new_variant (value);
g_variant_unref (value);
}
else
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_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);
if (length != 0)
memcpy (chunk->data, string, length);
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*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));
/* NOTE - the code to actually fill in the bloom filter here is missing.
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* Patches welcome!
*
* http://en.wikipedia.org/wiki/Bloom_filter
* http://0pointer.de/blog/projects/bloom.html
*/
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}
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);
index = 0;
for (bucket = 0; bucket < mytable->n_buckets; bucket++)
{
buckets[bucket] = guint32_to_le (index);
for (item = mytable->buckets[bucket]; item; item = item->next)
{
struct gvdb_hash_item *entry = items++;
const gchar *basename;
g_assert (index == guint32_from_le (item->assigned_index));
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);
entry->type = 'v';
}
if (item->child != NULL)
{
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guint32 children = 0, i = 0;
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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)
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offsets[i++] = child->assigned_index;
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g_assert (children == i);
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}
if (item->table != NULL)
{
entry->type = 'H';
file_builder_add_hash (fb, item->table, &entry->value.pointer);
}
index++;
}
}
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hash_table_free (mytable);
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}
static FileBuilder *
file_builder_new (gboolean byteswap)
{
FileBuilder *builder;
builder = g_slice_new (FileBuilder);
builder->chunks = g_queue_new ();
builder->offset = sizeof (struct gvdb_header);
builder->byteswap = byteswap;
return builder;
}
static void
file_builder_free (FileBuilder *fb)
{
g_queue_free (fb->chunks);
g_slice_free (FileBuilder, fb);
}
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static GString *
file_builder_serialise (FileBuilder *fb,
struct gvdb_pointer root)
{
struct gvdb_header header = { { 0, }, };
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GString *result;
if (fb->byteswap)
{
header.signature[0] = GVDB_SWAPPED_SIGNATURE0;
header.signature[1] = GVDB_SWAPPED_SIGNATURE1;
}
else
{
header.signature[0] = GVDB_SIGNATURE0;
header.signature[1] = GVDB_SIGNATURE1;
}
result = g_string_new (NULL);
header.root = root;
g_string_append_len (result, (gpointer) &header, sizeof header);
while (!g_queue_is_empty (fb->chunks))
{
FileChunk *chunk = g_queue_pop_head (fb->chunks);
if (result->len != chunk->offset)
{
gchar zero[8] = { 0, };
g_assert (chunk->offset > result->len);
g_assert (chunk->offset - result->len < 8);
g_string_append_len (result, zero, chunk->offset - result->len);
g_assert (result->len == chunk->offset);
}
g_string_append_len (result, chunk->data, chunk->size);
g_free (chunk->data);
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g_slice_free (FileChunk, chunk);
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}
return result;
}
gboolean
gvdb_table_write_contents (GHashTable *table,
const gchar *filename,
gboolean byteswap,
GError **error)
{
struct gvdb_pointer root;
gboolean status;
FileBuilder *fb;
GString *str;
g_return_val_if_fail (table != NULL, FALSE);
g_return_val_if_fail (filename != NULL, FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
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fb = file_builder_new (byteswap);
file_builder_add_hash (fb, table, &root);
str = file_builder_serialise (fb, root);
file_builder_free (fb);
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status = g_file_set_contents (filename, str->str, str->len, error);
g_string_free (str, TRUE);
return status;
}
typedef struct {
GBytes *contents; /* (owned) */
GFile *file; /* (owned) */
} WriteContentsData;
static WriteContentsData *
write_contents_data_new (GBytes *contents,
GFile *file)
{
WriteContentsData *data;
data = g_slice_new (WriteContentsData);
data->contents = g_bytes_ref (contents);
data->file = g_object_ref (file);
return data;
}
static void
write_contents_data_free (WriteContentsData *data)
{
g_bytes_unref (data->contents);
g_object_unref (data->file);
g_slice_free (WriteContentsData, data);
}
static void
replace_contents_cb (GObject *source_object,
GAsyncResult *result,
gpointer user_data)
{
GTask *task = user_data;
WriteContentsData *data = g_task_get_task_data (task);
GError *error = NULL;
g_return_if_fail (g_task_get_source_tag (task) == gvdb_table_write_contents_async);
if (!g_file_replace_contents_finish (data->file, result, NULL, &error))
g_task_return_error (task, g_steal_pointer (&error));
else
g_task_return_boolean (task, TRUE);
g_object_unref (task);
}
void
gvdb_table_write_contents_async (GHashTable *table,
const gchar *filename,
gboolean byteswap,
GCancellable *cancellable,
GAsyncReadyCallback callback,
gpointer user_data)
{
struct gvdb_pointer root;
FileBuilder *fb;
WriteContentsData *data;
GString *str;
GBytes *bytes;
GFile *file;
GTask *task;
g_return_if_fail (table != NULL);
g_return_if_fail (filename != NULL);
g_return_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable));
fb = file_builder_new (byteswap);
file_builder_add_hash (fb, table, &root);
str = file_builder_serialise (fb, root);
bytes = g_string_free_to_bytes (str);
file_builder_free (fb);
file = g_file_new_for_path (filename);
data = write_contents_data_new (bytes, file);
task = g_task_new (NULL, cancellable, callback, user_data);
g_task_set_task_data (task, data, (GDestroyNotify)write_contents_data_free);
g_task_set_source_tag (task, gvdb_table_write_contents_async);
g_file_replace_contents_async (file, str->str, str->len,
NULL, FALSE,
G_FILE_CREATE_PRIVATE | G_FILE_CREATE_REPLACE_DESTINATION,
cancellable, replace_contents_cb, g_steal_pointer (&task));
g_bytes_unref (bytes);
g_object_unref (file);
}
gboolean
gvdb_table_write_contents_finish (GHashTable *table,
GAsyncResult *result,
GError **error)
{
g_return_val_if_fail (table != NULL, FALSE);
g_return_val_if_fail (g_task_is_valid (result, NULL), FALSE);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
return g_task_propagate_boolean (G_TASK (result), error);
}