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buffer.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include <stdint.h>
20 #include <string.h>
21 
22 #include "atomic.h"
23 #include "buffer_internal.h"
24 #include "common.h"
25 #include "mem.h"
26 #include "thread.h"
27 
29  void (*free)(void *opaque, uint8_t *data),
30  void *opaque, int flags)
31 {
32  AVBufferRef *ref = NULL;
33  AVBuffer *buf = NULL;
34 
35  buf = av_mallocz(sizeof(*buf));
36  if (!buf)
37  return NULL;
38 
39  buf->data = data;
40  buf->size = size;
41  buf->free = free ? free : av_buffer_default_free;
42  buf->opaque = opaque;
43  buf->refcount = 1;
44 
45  if (flags & AV_BUFFER_FLAG_READONLY)
47 
48  ref = av_mallocz(sizeof(*ref));
49  if (!ref) {
50  av_freep(&buf);
51  return NULL;
52  }
53 
54  ref->buffer = buf;
55  ref->data = data;
56  ref->size = size;
57 
58  return ref;
59 }
60 
61 void av_buffer_default_free(void *opaque, uint8_t *data)
62 {
63  av_free(data);
64 }
65 
67 {
68  AVBufferRef *ret = NULL;
69  uint8_t *data = NULL;
70 
71  data = av_malloc(size);
72  if (!data)
73  return NULL;
74 
75  ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
76  if (!ret)
77  av_freep(&data);
78 
79  return ret;
80 }
81 
83 {
85  if (!ret)
86  return NULL;
87 
88  memset(ret->data, 0, size);
89  return ret;
90 }
91 
93 {
94  AVBufferRef *ret = av_mallocz(sizeof(*ret));
95 
96  if (!ret)
97  return NULL;
98 
99  *ret = *buf;
100 
102 
103  return ret;
104 }
105 
107 {
108  AVBuffer *b;
109 
110  if (!buf || !*buf)
111  return;
112  b = (*buf)->buffer;
113  av_freep(buf);
114 
116  b->free(b->opaque, b->data);
117  av_freep(&b);
118  }
119 }
120 
122 {
124  return 0;
125 
126  return avpriv_atomic_int_get(&buf->buffer->refcount) == 1;
127 }
128 
130 {
131  return buf->buffer->opaque;
132 }
133 
135 {
136  return buf->buffer->refcount;
137 }
138 
140 {
141  AVBufferRef *newbuf, *buf = *pbuf;
142 
143  if (av_buffer_is_writable(buf))
144  return 0;
145 
146  newbuf = av_buffer_alloc(buf->size);
147  if (!newbuf)
148  return AVERROR(ENOMEM);
149 
150  memcpy(newbuf->data, buf->data, buf->size);
151  av_buffer_unref(pbuf);
152  *pbuf = newbuf;
153 
154  return 0;
155 }
156 
157 int av_buffer_realloc(AVBufferRef **pbuf, int size)
158 {
159  AVBufferRef *buf = *pbuf;
160  uint8_t *tmp;
161 
162  if (!buf) {
163  /* allocate a new buffer with av_realloc(), so it will be reallocatable
164  * later */
165  uint8_t *data = av_realloc(NULL, size);
166  if (!data)
167  return AVERROR(ENOMEM);
168 
169  buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
170  if (!buf) {
171  av_freep(&data);
172  return AVERROR(ENOMEM);
173  }
174 
176  *pbuf = buf;
177 
178  return 0;
179  } else if (buf->size == size)
180  return 0;
181 
182  if (!(buf->buffer->flags & BUFFER_FLAG_REALLOCATABLE) ||
183  !av_buffer_is_writable(buf)) {
184  /* cannot realloc, allocate a new reallocable buffer and copy data */
185  AVBufferRef *new = NULL;
186 
187  av_buffer_realloc(&new, size);
188  if (!new)
189  return AVERROR(ENOMEM);
190 
191  memcpy(new->data, buf->data, FFMIN(size, buf->size));
192 
193  av_buffer_unref(pbuf);
194  *pbuf = new;
195  return 0;
196  }
197 
198  tmp = av_realloc(buf->buffer->data, size);
199  if (!tmp)
200  return AVERROR(ENOMEM);
201 
202  buf->buffer->data = buf->data = tmp;
203  buf->buffer->size = buf->size = size;
204  return 0;
205 }
206 
207 AVBufferPool *av_buffer_pool_init(int size, AVBufferRef* (*alloc)(int size))
208 {
209  AVBufferPool *pool = av_mallocz(sizeof(*pool));
210  if (!pool)
211  return NULL;
212 
213  ff_mutex_init(&pool->mutex, NULL);
214 
215  pool->size = size;
216  pool->alloc = alloc ? alloc : av_buffer_alloc;
217 
218  avpriv_atomic_int_set(&pool->refcount, 1);
219 
220  return pool;
221 }
222 
223 /*
224  * This function gets called when the pool has been uninited and
225  * all the buffers returned to it.
226  */
227 static void buffer_pool_free(AVBufferPool *pool)
228 {
229  while (pool->pool) {
230  BufferPoolEntry *buf = pool->pool;
231  pool->pool = buf->next;
232 
233  buf->free(buf->opaque, buf->data);
234  av_freep(&buf);
235  }
236  ff_mutex_destroy(&pool->mutex);
237  av_freep(&pool);
238 }
239 
241 {
242  AVBufferPool *pool;
243 
244  if (!ppool || !*ppool)
245  return;
246  pool = *ppool;
247  *ppool = NULL;
248 
249  if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
250  buffer_pool_free(pool);
251 }
252 
253 #if USE_ATOMICS
254 /* remove the whole buffer list from the pool and return it */
256 {
257  BufferPoolEntry *cur = *(void * volatile *)&pool->pool, *last = NULL;
258 
259  while (cur != last) {
260  last = cur;
261  cur = avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, last, NULL);
262  if (!cur)
263  return NULL;
264  }
265 
266  return cur;
267 }
268 
270 {
271  AVBufferPool *pool;
272  BufferPoolEntry *cur, *end = buf;
273 
274  if (!buf)
275  return;
276  pool = buf->pool;
277 
278  while (end->next)
279  end = end->next;
280 
281  while (avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, NULL, buf)) {
282  /* pool is not empty, retrieve it and append it to our list */
283  cur = get_pool(pool);
284  end->next = cur;
285  while (end->next)
286  end = end->next;
287  }
288 }
289 #endif
290 
291 static void pool_release_buffer(void *opaque, uint8_t *data)
292 {
293  BufferPoolEntry *buf = opaque;
294  AVBufferPool *pool = buf->pool;
295 
296  if(CONFIG_MEMORY_POISONING)
297  memset(buf->data, FF_MEMORY_POISON, pool->size);
298 
299 #if USE_ATOMICS
300  add_to_pool(buf);
301 #else
302  ff_mutex_lock(&pool->mutex);
303  buf->next = pool->pool;
304  pool->pool = buf;
305  ff_mutex_unlock(&pool->mutex);
306 #endif
307 
308  if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
309  buffer_pool_free(pool);
310 }
311 
312 /* allocate a new buffer and override its free() callback so that
313  * it is returned to the pool on free */
315 {
317  AVBufferRef *ret;
318 
319  ret = pool->alloc(pool->size);
320  if (!ret)
321  return NULL;
322 
323  buf = av_mallocz(sizeof(*buf));
324  if (!buf) {
325  av_buffer_unref(&ret);
326  return NULL;
327  }
328 
329  buf->data = ret->buffer->data;
330  buf->opaque = ret->buffer->opaque;
331  buf->free = ret->buffer->free;
332  buf->pool = pool;
333 
334  ret->buffer->opaque = buf;
336 
337 #if USE_ATOMICS
340 #endif
341 
342  return ret;
343 }
344 
346 {
347  AVBufferRef *ret;
349 
350 #if USE_ATOMICS
351  /* check whether the pool is empty */
352  buf = get_pool(pool);
353  if (!buf && pool->refcount <= pool->nb_allocated) {
354  av_log(NULL, AV_LOG_DEBUG, "Pool race dectected, spining to avoid overallocation and eventual OOM\n");
355  while (!buf && avpriv_atomic_int_get(&pool->refcount) <= avpriv_atomic_int_get(&pool->nb_allocated))
356  buf = get_pool(pool);
357  }
358 
359  if (!buf)
360  return pool_alloc_buffer(pool);
361 
362  /* keep the first entry, return the rest of the list to the pool */
363  add_to_pool(buf->next);
364  buf->next = NULL;
365 
366  ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
367  buf, 0);
368  if (!ret) {
369  add_to_pool(buf);
370  return NULL;
371  }
372 #else
373  ff_mutex_lock(&pool->mutex);
374  buf = pool->pool;
375  if (buf) {
376  ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
377  buf, 0);
378  if (ret) {
379  pool->pool = buf->next;
380  buf->next = NULL;
381  }
382  } else {
383  ret = pool_alloc_buffer(pool);
384  }
385  ff_mutex_unlock(&pool->mutex);
386 #endif
387 
388  if (ret)
390 
391  return ret;
392 }