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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  b = (*dst)->buffer;
111 
112  if (src) {
113  **dst = **src;
114  av_freep(src);
115  } else
116  av_freep(dst);
117 
119  b->free(b->opaque, b->data);
120  av_freep(&b);
121  }
122 }
123 
125 {
126  if (!buf || !*buf)
127  return;
128 
129  buffer_replace(buf, NULL);
130 }
131 
133 {
135  return 0;
136 
137  return avpriv_atomic_int_get(&buf->buffer->refcount) == 1;
138 }
139 
141 {
142  return buf->buffer->opaque;
143 }
144 
146 {
147  return buf->buffer->refcount;
148 }
149 
151 {
152  AVBufferRef *newbuf, *buf = *pbuf;
153 
154  if (av_buffer_is_writable(buf))
155  return 0;
156 
157  newbuf = av_buffer_alloc(buf->size);
158  if (!newbuf)
159  return AVERROR(ENOMEM);
160 
161  memcpy(newbuf->data, buf->data, buf->size);
162 
163  buffer_replace(pbuf, &newbuf);
164 
165  return 0;
166 }
167 
168 int av_buffer_realloc(AVBufferRef **pbuf, int size)
169 {
170  AVBufferRef *buf = *pbuf;
171  uint8_t *tmp;
172 
173  if (!buf) {
174  /* allocate a new buffer with av_realloc(), so it will be reallocatable
175  * later */
176  uint8_t *data = av_realloc(NULL, size);
177  if (!data)
178  return AVERROR(ENOMEM);
179 
180  buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
181  if (!buf) {
182  av_freep(&data);
183  return AVERROR(ENOMEM);
184  }
185 
187  *pbuf = buf;
188 
189  return 0;
190  } else if (buf->size == size)
191  return 0;
192 
193  if (!(buf->buffer->flags & BUFFER_FLAG_REALLOCATABLE) ||
194  !av_buffer_is_writable(buf)) {
195  /* cannot realloc, allocate a new reallocable buffer and copy data */
196  AVBufferRef *new = NULL;
197 
198  av_buffer_realloc(&new, size);
199  if (!new)
200  return AVERROR(ENOMEM);
201 
202  memcpy(new->data, buf->data, FFMIN(size, buf->size));
203 
204  buffer_replace(pbuf, &new);
205  return 0;
206  }
207 
208  tmp = av_realloc(buf->buffer->data, size);
209  if (!tmp)
210  return AVERROR(ENOMEM);
211 
212  buf->buffer->data = buf->data = tmp;
213  buf->buffer->size = buf->size = size;
214  return 0;
215 }
216 
217 AVBufferPool *av_buffer_pool_init(int size, AVBufferRef* (*alloc)(int size))
218 {
219  AVBufferPool *pool = av_mallocz(sizeof(*pool));
220  if (!pool)
221  return NULL;
222 
223  ff_mutex_init(&pool->mutex, NULL);
224 
225  pool->size = size;
226  pool->alloc = alloc ? alloc : av_buffer_alloc;
227 
228  avpriv_atomic_int_set(&pool->refcount, 1);
229 
230  return pool;
231 }
232 
233 /*
234  * This function gets called when the pool has been uninited and
235  * all the buffers returned to it.
236  */
237 static void buffer_pool_free(AVBufferPool *pool)
238 {
239  while (pool->pool) {
240  BufferPoolEntry *buf = pool->pool;
241  pool->pool = buf->next;
242 
243  buf->free(buf->opaque, buf->data);
244  av_freep(&buf);
245  }
246  ff_mutex_destroy(&pool->mutex);
247  av_freep(&pool);
248 }
249 
251 {
252  AVBufferPool *pool;
253 
254  if (!ppool || !*ppool)
255  return;
256  pool = *ppool;
257  *ppool = NULL;
258 
259  if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
260  buffer_pool_free(pool);
261 }
262 
263 #if USE_ATOMICS
264 /* remove the whole buffer list from the pool and return it */
266 {
267  BufferPoolEntry *cur = *(void * volatile *)&pool->pool, *last = NULL;
268 
269  while (cur != last) {
270  last = cur;
271  cur = avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, last, NULL);
272  if (!cur)
273  return NULL;
274  }
275 
276  return cur;
277 }
278 
280 {
281  AVBufferPool *pool;
282  BufferPoolEntry *cur, *end = buf;
283 
284  if (!buf)
285  return;
286  pool = buf->pool;
287 
288  while (end->next)
289  end = end->next;
290 
291  while (avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, NULL, buf)) {
292  /* pool is not empty, retrieve it and append it to our list */
293  cur = get_pool(pool);
294  end->next = cur;
295  while (end->next)
296  end = end->next;
297  }
298 }
299 #endif
300 
301 static void pool_release_buffer(void *opaque, uint8_t *data)
302 {
303  BufferPoolEntry *buf = opaque;
304  AVBufferPool *pool = buf->pool;
305 
306  if(CONFIG_MEMORY_POISONING)
307  memset(buf->data, FF_MEMORY_POISON, pool->size);
308 
309 #if USE_ATOMICS
310  add_to_pool(buf);
311 #else
312  ff_mutex_lock(&pool->mutex);
313  buf->next = pool->pool;
314  pool->pool = buf;
315  ff_mutex_unlock(&pool->mutex);
316 #endif
317 
318  if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
319  buffer_pool_free(pool);
320 }
321 
322 /* allocate a new buffer and override its free() callback so that
323  * it is returned to the pool on free */
325 {
327  AVBufferRef *ret;
328 
329  ret = pool->alloc(pool->size);
330  if (!ret)
331  return NULL;
332 
333  buf = av_mallocz(sizeof(*buf));
334  if (!buf) {
335  av_buffer_unref(&ret);
336  return NULL;
337  }
338 
339  buf->data = ret->buffer->data;
340  buf->opaque = ret->buffer->opaque;
341  buf->free = ret->buffer->free;
342  buf->pool = pool;
343 
344  ret->buffer->opaque = buf;
346 
347 #if USE_ATOMICS
350 #endif
351 
352  return ret;
353 }
354 
356 {
357  AVBufferRef *ret;
359 
360 #if USE_ATOMICS
361  /* check whether the pool is empty */
362  buf = get_pool(pool);
363  if (!buf && pool->refcount <= pool->nb_allocated) {
364  av_log(NULL, AV_LOG_DEBUG, "Pool race dectected, spining to avoid overallocation and eventual OOM\n");
365  while (!buf && avpriv_atomic_int_get(&pool->refcount) <= avpriv_atomic_int_get(&pool->nb_allocated))
366  buf = get_pool(pool);
367  }
368 
369  if (!buf)
370  return pool_alloc_buffer(pool);
371 
372  /* keep the first entry, return the rest of the list to the pool */
373  add_to_pool(buf->next);
374  buf->next = NULL;
375 
376  ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
377  buf, 0);
378  if (!ret) {
379  add_to_pool(buf);
380  return NULL;
381  }
382 #else
383  ff_mutex_lock(&pool->mutex);
384  buf = pool->pool;
385  if (buf) {
386  ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
387  buf, 0);
388  if (ret) {
389  pool->pool = buf->next;
390  buf->next = NULL;
391  }
392  } else {
393  ret = pool_alloc_buffer(pool);
394  }
395  ff_mutex_unlock(&pool->mutex);
396 #endif
397 
398  if (ret)
400 
401  return ret;
402 }