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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 
28  void (*free)(void *opaque, uint8_t *data),
29  void *opaque, int flags)
30 {
31  AVBufferRef *ref = NULL;
32  AVBuffer *buf = NULL;
33 
34  buf = av_mallocz(sizeof(*buf));
35  if (!buf)
36  return NULL;
37 
38  buf->data = data;
39  buf->size = size;
40  buf->free = free ? free : av_buffer_default_free;
41  buf->opaque = opaque;
42  buf->refcount = 1;
43 
44  if (flags & AV_BUFFER_FLAG_READONLY)
46 
47  ref = av_mallocz(sizeof(*ref));
48  if (!ref) {
49  av_freep(&buf);
50  return NULL;
51  }
52 
53  ref->buffer = buf;
54  ref->data = data;
55  ref->size = size;
56 
57  return ref;
58 }
59 
60 void av_buffer_default_free(void *opaque, uint8_t *data)
61 {
62  av_free(data);
63 }
64 
66 {
67  AVBufferRef *ret = NULL;
68  uint8_t *data = NULL;
69 
70  data = av_malloc(size);
71  if (!data)
72  return NULL;
73 
74  ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
75  if (!ret)
76  av_freep(&data);
77 
78  return ret;
79 }
80 
82 {
84  if (!ret)
85  return NULL;
86 
87  memset(ret->data, 0, size);
88  return ret;
89 }
90 
92 {
93  AVBufferRef *ret = av_mallocz(sizeof(*ret));
94 
95  if (!ret)
96  return NULL;
97 
98  *ret = *buf;
99 
101 
102  return ret;
103 }
104 
106 {
107  AVBuffer *b;
108 
109  if (!buf || !*buf)
110  return;
111  b = (*buf)->buffer;
112  av_freep(buf);
113 
115  b->free(b->opaque, b->data);
116  av_freep(&b);
117  }
118 }
119 
121 {
123  return 0;
124 
125  return avpriv_atomic_int_get(&buf->buffer->refcount) == 1;
126 }
127 
129 {
130  return buf->buffer->opaque;
131 }
132 
134 {
135  return buf->buffer->refcount;
136 }
137 
139 {
140  AVBufferRef *newbuf, *buf = *pbuf;
141 
142  if (av_buffer_is_writable(buf))
143  return 0;
144 
145  newbuf = av_buffer_alloc(buf->size);
146  if (!newbuf)
147  return AVERROR(ENOMEM);
148 
149  memcpy(newbuf->data, buf->data, buf->size);
150  av_buffer_unref(pbuf);
151  *pbuf = newbuf;
152 
153  return 0;
154 }
155 
156 int av_buffer_realloc(AVBufferRef **pbuf, int size)
157 {
158  AVBufferRef *buf = *pbuf;
159  uint8_t *tmp;
160 
161  if (!buf) {
162  /* allocate a new buffer with av_realloc(), so it will be reallocatable
163  * later */
164  uint8_t *data = av_realloc(NULL, size);
165  if (!data)
166  return AVERROR(ENOMEM);
167 
168  buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
169  if (!buf) {
170  av_freep(&data);
171  return AVERROR(ENOMEM);
172  }
173 
175  *pbuf = buf;
176 
177  return 0;
178  } else if (buf->size == size)
179  return 0;
180 
181  if (!(buf->buffer->flags & BUFFER_FLAG_REALLOCATABLE) ||
182  !av_buffer_is_writable(buf)) {
183  /* cannot realloc, allocate a new reallocable buffer and copy data */
184  AVBufferRef *new = NULL;
185 
186  av_buffer_realloc(&new, size);
187  if (!new)
188  return AVERROR(ENOMEM);
189 
190  memcpy(new->data, buf->data, FFMIN(size, buf->size));
191 
192  av_buffer_unref(pbuf);
193  *pbuf = new;
194  return 0;
195  }
196 
197  tmp = av_realloc(buf->buffer->data, size);
198  if (!tmp)
199  return AVERROR(ENOMEM);
200 
201  buf->buffer->data = buf->data = tmp;
202  buf->buffer->size = buf->size = size;
203  return 0;
204 }
205 
206 AVBufferPool *av_buffer_pool_init(int size, AVBufferRef* (*alloc)(int size))
207 {
208  AVBufferPool *pool = av_mallocz(sizeof(*pool));
209  if (!pool)
210  return NULL;
211 
212  pool->size = size;
213  pool->alloc = alloc ? alloc : av_buffer_alloc;
214 
215  avpriv_atomic_int_set(&pool->refcount, 1);
216 
217  return pool;
218 }
219 
220 /*
221  * This function gets called when the pool has been uninited and
222  * all the buffers returned to it.
223  */
224 static void buffer_pool_free(AVBufferPool *pool)
225 {
226  while (pool->pool) {
227  BufferPoolEntry *buf = pool->pool;
228  pool->pool = buf->next;
229 
230  buf->free(buf->opaque, buf->data);
231  av_freep(&buf);
232  }
233  av_freep(&pool);
234 }
235 
237 {
238  AVBufferPool *pool;
239 
240  if (!ppool || !*ppool)
241  return;
242  pool = *ppool;
243  *ppool = NULL;
244 
245  if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
246  buffer_pool_free(pool);
247 }
248 
249 /* remove the whole buffer list from the pool and return it */
251 {
252  BufferPoolEntry *cur = *(void * volatile *)&pool->pool, *last = NULL;
253 
254  while (cur != last) {
255  last = cur;
256  cur = avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, last, NULL);
257  if (!cur)
258  return NULL;
259  }
260 
261  return cur;
262 }
263 
265 {
266  AVBufferPool *pool;
267  BufferPoolEntry *cur, *end = buf;
268 
269  if (!buf)
270  return;
271  pool = buf->pool;
272 
273  while (end->next)
274  end = end->next;
275 
276  while (avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, NULL, buf)) {
277  /* pool is not empty, retrieve it and append it to our list */
278  cur = get_pool(pool);
279  end->next = cur;
280  while (end->next)
281  end = end->next;
282  }
283 }
284 
285 static void pool_release_buffer(void *opaque, uint8_t *data)
286 {
287  BufferPoolEntry *buf = opaque;
288  AVBufferPool *pool = buf->pool;
289 
290  if(CONFIG_MEMORY_POISONING)
291  memset(buf->data, FF_MEMORY_POISON, pool->size);
292 
293  add_to_pool(buf);
294  if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
295  buffer_pool_free(pool);
296 }
297 
298 /* allocate a new buffer and override its free() callback so that
299  * it is returned to the pool on free */
301 {
303  AVBufferRef *ret;
304 
305  ret = pool->alloc(pool->size);
306  if (!ret)
307  return NULL;
308 
309  buf = av_mallocz(sizeof(*buf));
310  if (!buf) {
311  av_buffer_unref(&ret);
312  return NULL;
313  }
314 
315  buf->data = ret->buffer->data;
316  buf->opaque = ret->buffer->opaque;
317  buf->free = ret->buffer->free;
318  buf->pool = pool;
319 
320  ret->buffer->opaque = buf;
322 
325 
326  return ret;
327 }
328 
330 {
331  AVBufferRef *ret;
333 
334  /* check whether the pool is empty */
335  buf = get_pool(pool);
336  if (!buf && pool->refcount <= pool->nb_allocated) {
337  av_log(NULL, AV_LOG_DEBUG, "Pool race dectected, spining to avoid overallocation and eventual OOM\n");
338  while (!buf && avpriv_atomic_int_get(&pool->refcount) <= avpriv_atomic_int_get(&pool->nb_allocated))
339  buf = get_pool(pool);
340  }
341 
342  if (!buf)
343  return pool_alloc_buffer(pool);
344 
345  /* keep the first entry, return the rest of the list to the pool */
346  add_to_pool(buf->next);
347  buf->next = NULL;
348 
349  ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
350  buf, 0);
351  if (!ret) {
352  add_to_pool(buf);
353  return NULL;
354  }
356 
357  return ret;
358 }