swfdec/swfdec_constant_pool.c

   1 /* Swfdec
   2  * Copyright (C) 2007-2008 Benjamin Otte <otte@gnome.org>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  * Boston, MA  02110-1301  USA
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include "swfdec_constant_pool.h"
  25 #include "swfdec_as_strings.h"
  26 #include "swfdec_bits.h"
  27 #include "swfdec_debug.h"
  28
  29 struct _SwfdecConstantPool {
  30   SwfdecAsContext *     context;        /* context we are attached to or NULL */
  31   SwfdecBuffer *        buffer;         /* the buffer the strings were read from */
  32   guint                 refcount;       /* reference count */
  33   guint                 n_strings;      /* number of strings */
  34   char *                strings[1];     /* n_strings strings */
  35 };
  36
  37 /**
  38  * swfdec_constant_pool_new:
  39  * @context: a context to attach strings to or %NULL
  40  * @buffer: buffer to read constant pool from
  41  * @version: the Flash version to use when reading the strings
  42  *
  43  * Creates a new constant pool from the given @buffer. If the buffer is in the
  44  * wrong format, %NULL is returned. If a @context was given, the strings are
  45  * added to the context. This means the strings in the pool will be
  46  * garbage-collected already. When using a non-%NULL @context, the pool does
  47  * will not add a reference to the context. It is your responsibility to hold a
  48  * reference to the context while you use the pool.
  49  *
  50  * Returns: a new constant pool or %NULL
  51  **/
  52 SwfdecConstantPool *
  53 swfdec_constant_pool_new (SwfdecAsContext *context, SwfdecBuffer *buffer, guint version)
  54 {
  55   guint i, n;
  56   gsize size;
  57   SwfdecBits bits;
  58   SwfdecConstantPool *pool;
  59
  60   g_return_val_if_fail (context == NULL || SWFDEC_IS_AS_CONTEXT (context), NULL);
  61   g_return_val_if_fail (buffer != NULL, NULL);
  62
  63   /* try to find the pool in the context's cache */
  64   if (context) {
  65     pool = g_hash_table_lookup (context->constant_pools, buffer->data);
  66     if (pool)
  67       return swfdec_constant_pool_ref (pool);
  68   }
  69
  70   swfdec_bits_init (&bits, buffer);
  71
  72   n = swfdec_bits_get_u16 (&bits);
  73
  74   size = sizeof (SwfdecConstantPool) + (MAX (1, n) - 1) * sizeof (char *);
  75   pool = g_slice_alloc0 (size);
  76   pool->n_strings = n;
  77   for (i = 0; i < n && swfdec_bits_left (&bits); i++) {
  78     pool->strings[i] = swfdec_bits_get_string (&bits, version);
  79     if (pool->strings[i] == NULL) {
  80       SWFDEC_ERROR ("constant pool index %u invalid, using empty string instead.", i);
  81       pool->strings[i] = context ? (char *) SWFDEC_AS_STR_EMPTY : g_strdup ("");
  82     } else if (context) {
  83       pool->strings[i] = (char *) swfdec_as_context_give_string (context, pool->strings[i]);
  84     }
  85   }
  86   if (swfdec_bits_left (&bits)) {
  87     SWFDEC_WARNING ("constant pool didn't consume whole buffer (%u bytes leftover)", swfdec_bits_left (&bits) / 8);
  88   }
  89   pool->buffer = swfdec_buffer_ref (buffer);
  90   pool->refcount = 1;
  91   /* put pool into the context's cache */
  92   if (context) {
  93     pool->context = context;
  94     g_hash_table_insert (context->constant_pools, buffer->data, pool);
  95     swfdec_constant_pool_ref (pool);
  96   }
  97   return pool;
  98 }
  99
 100 /**
 101  * swfdec_constant_pool_ref:
 102  * @pool: a constant pool
 103  *
 104  * Increases the constant pool's reference by one.
 105  *
 106  * Returns: the passed in @pool.
 107  **/
 108 SwfdecConstantPool *
 109 swfdec_constant_pool_ref (SwfdecConstantPool *pool)
 110 {
 111   g_return_val_if_fail (SWFDEC_IS_CONSTANT_POOL (pool), NULL);
 112
 113   pool->refcount++;
 114
 115   return pool;
 116 }
 117
 118 /**
 119  * swfdec_constant_pool_unref:
 120  * @pool: the pool to unref
 121  *
 122  * Removes a reference from the pool. If no more references are left, the pool
 123  * will be freed.
 124  **/
 125 void
 126 swfdec_constant_pool_unref (SwfdecConstantPool *pool)
 127 {
 128   g_return_if_fail (SWFDEC_IS_CONSTANT_POOL (pool));
 129   g_return_if_fail (pool->refcount > 0);
 130
 131   pool->refcount--;
 132   if (pool->refcount)
 133     return;
 134
 135   if (pool->context == NULL) {
 136     guint i;
 137     for (i = 0; i < pool->n_strings; i++) {
 138       g_free (pool->strings[i]);
 139     }
 140   }
 141   swfdec_buffer_unref (pool->buffer);
 142   g_slice_free1 (sizeof (SwfdecConstantPool) + (MAX (1, pool->n_strings) - 1) * sizeof (char *), pool);
 143 }
 144
 145 gboolean
 146 swfdec_constant_pool_collect (SwfdecConstantPool *pool)
 147 {
 148   if (pool->refcount) {
 149     swfdec_constant_pool_unref (pool);
 150     return TRUE;
 151   }
 152   return FALSE;
 153 }
 154
 155 /**
 156  * swfdec_constant_pool_size:
 157  * @pool: a pool
 158  *
 159  * Queries the number of strings in this pool.
 160  *
 161  * Returns: The number of strings in this @pool
 162  **/
 163 guint
 164 swfdec_constant_pool_size (SwfdecConstantPool *pool)
 165 {
 166   g_return_val_if_fail (SWFDEC_IS_CONSTANT_POOL (pool), 0);
 167
 168   return pool->n_strings;
 169 }
 170
 171 /**
 172  * swfdec_constant_pool_get:
 173  * @pool: a pool
 174  * @i: index of the string to get
 175  *
 176  * Gets the requested string from the pool. The index must not excess the
 177  * number of elements in the pool. If the constant pool was created with a
 178  * context attached, the returned string will be garbage-collected already.
 179  *
 180  * Returns: the string at position @i
 181  **/
 182 const char *
 183 swfdec_constant_pool_get (SwfdecConstantPool *pool, guint i)
 184 {
 185   g_return_val_if_fail (SWFDEC_IS_CONSTANT_POOL (pool), NULL);
 186   g_return_val_if_fail (i < pool->n_strings, NULL);
 187
 188   return pool->strings[i];
 189 }
 190
 191 /**
 192  * swfdec_constant_pool_get_buffer:
 193  * @pool: a constant pool
 194  *
 195  * Gets the buffer the pool was created from
 196  *
 197  * Returns: the buffer this pool was created from.
 198  **/
 199 SwfdecBuffer *
 200 swfdec_constant_pool_get_buffer (SwfdecConstantPool *pool)
 201 {
 202   g_return_val_if_fail (SWFDEC_IS_CONSTANT_POOL (pool), NULL);
 203
 204   return pool->buffer;
 205 }
 206