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 <stdatomic.h>
20 #include <stdint.h>
21 #include <string.h>
22 
23 #include "avassert.h"
24 #include "buffer_internal.h"
25 #include "common.h"
26 #include "mem.h"
27 #include "thread.h"
28 
av_buffer_create(uint8_t * data,buffer_size_t size,void (* free)(void * opaque,uint8_t * data),void * opaque,int flags)29 AVBufferRef *av_buffer_create(uint8_t *data, buffer_size_t size,
30                               void (*free)(void *opaque, uint8_t *data),
31                               void *opaque, int flags)
32 {
33     AVBufferRef *ref = NULL;
34     AVBuffer    *buf = NULL;
35 
36     buf = av_mallocz(sizeof(*buf));
37     if (!buf)
38         return NULL;
39 
40     buf->data     = data;
41     buf->size     = size;
42     buf->free     = free ? free : av_buffer_default_free;
43     buf->opaque   = opaque;
44 
45     atomic_init(&buf->refcount, 1);
46 
47     buf->flags = flags;
48 
49     ref = av_mallocz(sizeof(*ref));
50     if (!ref) {
51         av_freep(&buf);
52         return NULL;
53     }
54 
55     ref->buffer = buf;
56     ref->data   = data;
57     ref->size   = size;
58 
59     return ref;
60 }
61 
av_buffer_default_free(void * opaque,uint8_t * data)62 void av_buffer_default_free(void *opaque, uint8_t *data)
63 {
64     av_free(data);
65 }
66 
av_buffer_alloc(buffer_size_t size)67 AVBufferRef *av_buffer_alloc(buffer_size_t size)
68 {
69     AVBufferRef *ret = NULL;
70     uint8_t    *data = NULL;
71 
72     data = av_malloc(size);
73     if (!data)
74         return NULL;
75 
76     ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
77     if (!ret)
78         av_freep(&data);
79 
80     return ret;
81 }
82 
av_buffer_allocz(buffer_size_t size)83 AVBufferRef *av_buffer_allocz(buffer_size_t size)
84 {
85     AVBufferRef *ret = av_buffer_alloc(size);
86     if (!ret)
87         return NULL;
88 
89     memset(ret->data, 0, size);
90     return ret;
91 }
92 
av_buffer_ref(AVBufferRef * buf)93 AVBufferRef *av_buffer_ref(AVBufferRef *buf)
94 {
95     AVBufferRef *ret = av_mallocz(sizeof(*ret));
96 
97     if (!ret)
98         return NULL;
99 
100     *ret = *buf;
101 
102     atomic_fetch_add_explicit(&buf->buffer->refcount, 1, memory_order_relaxed);
103 
104     return ret;
105 }
106 
buffer_replace(AVBufferRef ** dst,AVBufferRef ** src)107 static void buffer_replace(AVBufferRef **dst, AVBufferRef **src)
108 {
109     AVBuffer *b;
110 
111     b = (*dst)->buffer;
112 
113     if (src) {
114         **dst = **src;
115         av_freep(src);
116     } else
117         av_freep(dst);
118 
119     if (atomic_fetch_sub_explicit(&b->refcount, 1, memory_order_acq_rel) == 1) {
120         b->free(b->opaque, b->data);
121         av_freep(&b);
122     }
123 }
124 
av_buffer_unref(AVBufferRef ** buf)125 void av_buffer_unref(AVBufferRef **buf)
126 {
127     if (!buf || !*buf)
128         return;
129 
130     buffer_replace(buf, NULL);
131 }
132 
av_buffer_is_writable(const AVBufferRef * buf)133 int av_buffer_is_writable(const AVBufferRef *buf)
134 {
135     if (buf->buffer->flags & AV_BUFFER_FLAG_READONLY)
136         return 0;
137 
138     return atomic_load(&buf->buffer->refcount) == 1;
139 }
140 
av_buffer_get_opaque(const AVBufferRef * buf)141 void *av_buffer_get_opaque(const AVBufferRef *buf)
142 {
143     return buf->buffer->opaque;
144 }
145 
av_buffer_get_ref_count(const AVBufferRef * buf)146 int av_buffer_get_ref_count(const AVBufferRef *buf)
147 {
148     return atomic_load(&buf->buffer->refcount);
149 }
150 
av_buffer_make_writable(AVBufferRef ** pbuf)151 int av_buffer_make_writable(AVBufferRef **pbuf)
152 {
153     AVBufferRef *newbuf, *buf = *pbuf;
154 
155     if (av_buffer_is_writable(buf))
156         return 0;
157 
158     newbuf = av_buffer_alloc(buf->size);
159     if (!newbuf)
160         return AVERROR(ENOMEM);
161 
162     memcpy(newbuf->data, buf->data, buf->size);
163 
164     buffer_replace(pbuf, &newbuf);
165 
166     return 0;
167 }
168 
av_buffer_realloc(AVBufferRef ** pbuf,buffer_size_t size)169 int av_buffer_realloc(AVBufferRef **pbuf, buffer_size_t size)
170 {
171     AVBufferRef *buf = *pbuf;
172     uint8_t *tmp;
173     int ret;
174 
175     if (!buf) {
176         /* allocate a new buffer with av_realloc(), so it will be reallocatable
177          * later */
178         uint8_t *data = av_realloc(NULL, size);
179         if (!data)
180             return AVERROR(ENOMEM);
181 
182         buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
183         if (!buf) {
184             av_freep(&data);
185             return AVERROR(ENOMEM);
186         }
187 
188         buf->buffer->flags_internal |= BUFFER_FLAG_REALLOCATABLE;
189         *pbuf = buf;
190 
191         return 0;
192     } else if (buf->size == size)
193         return 0;
194 
195     if (!(buf->buffer->flags_internal & BUFFER_FLAG_REALLOCATABLE) ||
196         !av_buffer_is_writable(buf) || buf->data != buf->buffer->data) {
197         /* cannot realloc, allocate a new reallocable buffer and copy data */
198         AVBufferRef *new = NULL;
199 
200         ret = av_buffer_realloc(&new, size);
201         if (ret < 0)
202             return ret;
203 
204         memcpy(new->data, buf->data, FFMIN(size, buf->size));
205 
206         buffer_replace(pbuf, &new);
207         return 0;
208     }
209 
210     tmp = av_realloc(buf->buffer->data, size);
211     if (!tmp)
212         return AVERROR(ENOMEM);
213 
214     buf->buffer->data = buf->data = tmp;
215     buf->buffer->size = buf->size = size;
216     return 0;
217 }
218 
av_buffer_replace(AVBufferRef ** pdst,AVBufferRef * src)219 int av_buffer_replace(AVBufferRef **pdst, AVBufferRef *src)
220 {
221     AVBufferRef *dst = *pdst;
222     AVBufferRef *tmp;
223 
224     if (!src) {
225         av_buffer_unref(pdst);
226         return 0;
227     }
228 
229     if (dst && dst->buffer == src->buffer) {
230         /* make sure the data pointers match */
231         dst->data = src->data;
232         dst->size = src->size;
233         return 0;
234     }
235 
236     tmp = av_buffer_ref(src);
237     if (!tmp)
238         return AVERROR(ENOMEM);
239 
240     av_buffer_unref(pdst);
241     *pdst = tmp;
242     return 0;
243 }
244 
av_buffer_pool_init2(buffer_size_t size,void * opaque,AVBufferRef * (* alloc)(void * opaque,buffer_size_t size),void (* pool_free)(void * opaque))245 AVBufferPool *av_buffer_pool_init2(buffer_size_t size, void *opaque,
246                                    AVBufferRef* (*alloc)(void *opaque, buffer_size_t size),
247                                    void (*pool_free)(void *opaque))
248 {
249     AVBufferPool *pool = av_mallocz(sizeof(*pool));
250     if (!pool)
251         return NULL;
252 
253     ff_mutex_init(&pool->mutex, NULL);
254 
255     pool->size      = size;
256     pool->opaque    = opaque;
257     pool->alloc2    = alloc;
258     pool->alloc     = av_buffer_alloc; // fallback
259     pool->pool_free = pool_free;
260 
261     atomic_init(&pool->refcount, 1);
262 
263     return pool;
264 }
265 
av_buffer_pool_init(buffer_size_t size,AVBufferRef * (* alloc)(buffer_size_t size))266 AVBufferPool *av_buffer_pool_init(buffer_size_t size, AVBufferRef* (*alloc)(buffer_size_t size))
267 {
268     AVBufferPool *pool = av_mallocz(sizeof(*pool));
269     if (!pool)
270         return NULL;
271 
272     ff_mutex_init(&pool->mutex, NULL);
273 
274     pool->size     = size;
275     pool->alloc    = alloc ? alloc : av_buffer_alloc;
276 
277     atomic_init(&pool->refcount, 1);
278 
279     return pool;
280 }
281 
buffer_pool_flush(AVBufferPool * pool)282 static void buffer_pool_flush(AVBufferPool *pool)
283 {
284     while (pool->pool) {
285         BufferPoolEntry *buf = pool->pool;
286         pool->pool = buf->next;
287 
288         buf->free(buf->opaque, buf->data);
289         av_freep(&buf);
290     }
291 }
292 
293 /*
294  * This function gets called when the pool has been uninited and
295  * all the buffers returned to it.
296  */
buffer_pool_free(AVBufferPool * pool)297 static void buffer_pool_free(AVBufferPool *pool)
298 {
299     buffer_pool_flush(pool);
300     ff_mutex_destroy(&pool->mutex);
301 
302     if (pool->pool_free)
303         pool->pool_free(pool->opaque);
304 
305     av_freep(&pool);
306 }
307 
av_buffer_pool_uninit(AVBufferPool ** ppool)308 void av_buffer_pool_uninit(AVBufferPool **ppool)
309 {
310     AVBufferPool *pool;
311 
312     if (!ppool || !*ppool)
313         return;
314     pool   = *ppool;
315     *ppool = NULL;
316 
317     ff_mutex_lock(&pool->mutex);
318     buffer_pool_flush(pool);
319     ff_mutex_unlock(&pool->mutex);
320 
321     if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
322         buffer_pool_free(pool);
323 }
324 
pool_release_buffer(void * opaque,uint8_t * data)325 static void pool_release_buffer(void *opaque, uint8_t *data)
326 {
327     BufferPoolEntry *buf = opaque;
328     AVBufferPool *pool = buf->pool;
329 
330     if(CONFIG_MEMORY_POISONING)
331         memset(buf->data, FF_MEMORY_POISON, pool->size);
332 
333     ff_mutex_lock(&pool->mutex);
334     buf->next = pool->pool;
335     pool->pool = buf;
336     ff_mutex_unlock(&pool->mutex);
337 
338     if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
339         buffer_pool_free(pool);
340 }
341 
342 /* allocate a new buffer and override its free() callback so that
343  * it is returned to the pool on free */
pool_alloc_buffer(AVBufferPool * pool)344 static AVBufferRef *pool_alloc_buffer(AVBufferPool *pool)
345 {
346     BufferPoolEntry *buf;
347     AVBufferRef     *ret;
348 
349     av_assert0(pool->alloc || pool->alloc2);
350 
351     ret = pool->alloc2 ? pool->alloc2(pool->opaque, pool->size) :
352                          pool->alloc(pool->size);
353     if (!ret)
354         return NULL;
355 
356     buf = av_mallocz(sizeof(*buf));
357     if (!buf) {
358         av_buffer_unref(&ret);
359         return NULL;
360     }
361 
362     buf->data   = ret->buffer->data;
363     buf->opaque = ret->buffer->opaque;
364     buf->free   = ret->buffer->free;
365     buf->pool   = pool;
366 
367     ret->buffer->opaque = buf;
368     ret->buffer->free   = pool_release_buffer;
369 
370     return ret;
371 }
372 
av_buffer_pool_get(AVBufferPool * pool)373 AVBufferRef *av_buffer_pool_get(AVBufferPool *pool)
374 {
375     AVBufferRef *ret;
376     BufferPoolEntry *buf;
377 
378     ff_mutex_lock(&pool->mutex);
379     buf = pool->pool;
380     if (buf) {
381         ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
382                                buf, 0);
383         if (ret) {
384             pool->pool = buf->next;
385             buf->next = NULL;
386         }
387     } else {
388         ret = pool_alloc_buffer(pool);
389     }
390     ff_mutex_unlock(&pool->mutex);
391 
392     if (ret)
393         atomic_fetch_add_explicit(&pool->refcount, 1, memory_order_relaxed);
394 
395     return ret;
396 }
397 
av_buffer_pool_buffer_get_opaque(AVBufferRef * ref)398 void *av_buffer_pool_buffer_get_opaque(AVBufferRef *ref)
399 {
400     BufferPoolEntry *buf = ref->buffer->opaque;
401     av_assert0(buf);
402     return buf->opaque;
403 }
404