FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavutil/refstruct.c
Date: 2025-08-19 23:55:23
Exec Total Coverage
Lines: 150 163 92.0%
Functions: 20 20 100.0%
Branches: 46 58 79.3%
Line Branch Exec Source
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 "refstruct.h"
24
25 #include "avassert.h"
26 #include "error.h"
27 #include "macros.h"
28 #include "mem.h"
29 #include "mem_internal.h"
30 #include "thread.h"
31
32 #ifndef REFSTRUCT_CHECKED
33 #ifndef ASSERT_LEVEL
34 #define ASSERT_LEVEL 0
35 #endif
36 #define REFSTRUCT_CHECKED (ASSERT_LEVEL >= 1)
37 #endif
38
39 #if REFSTRUCT_CHECKED
40 #define ff_assert(cond) av_assert0(cond)
41 #else
42 #define ff_assert(cond) ((void)0)
43 #endif
44
45 #define REFSTRUCT_COOKIE AV_NE((uint64_t)MKBETAG('R', 'e', 'f', 'S') << 32 | MKBETAG('t', 'r', 'u', 'c'), \
46 MKTAG('R', 'e', 'f', 'S') | (uint64_t)MKTAG('t', 'r', 'u', 'c') << 32)
47
48 #ifndef _MSC_VER
49 #define REFCOUNT_OFFSET FFALIGN(sizeof(RefCount), FFMAX(ALIGN_64, _Alignof(max_align_t)))
50 #else
51 #define REFCOUNT_OFFSET FFALIGN(sizeof(RefCount), ALIGN_64)
52 #endif
53
54 typedef struct RefCount {
55 /**
56 * An uintptr_t is big enough to hold the address of every reference,
57 * so no overflow can happen when incrementing the refcount as long as
58 * the user does not throw away references.
59 */
60 atomic_uintptr_t refcount;
61 AVRefStructOpaque opaque;
62 void (*free_cb)(AVRefStructOpaque opaque, void *obj);
63 void (*free)(void *ref);
64
65 #if REFSTRUCT_CHECKED
66 uint64_t cookie;
67 #endif
68 } RefCount;
69
70 7523327 static RefCount *get_refcount(void *obj)
71 {
72 7523327 RefCount *ref = (RefCount*)((char*)obj - REFCOUNT_OFFSET);
73 ff_assert(ref->cookie == REFSTRUCT_COOKIE);
74 7523327 return ref;
75 }
76
77 306 static const RefCount *cget_refcount(const void *obj)
78 {
79 306 const RefCount *ref = (const RefCount*)((const char*)obj - REFCOUNT_OFFSET);
80 ff_assert(ref->cookie == REFSTRUCT_COOKIE);
81 306 return ref;
82 }
83
84 5875338 static void *get_userdata(void *buf)
85 {
86 5875338 return (char*)buf + REFCOUNT_OFFSET;
87 }
88
89 1272103 static void refcount_init(RefCount *ref, AVRefStructOpaque opaque,
90 void (*free_cb)(AVRefStructOpaque opaque, void *obj))
91 {
92 1272103 atomic_init(&ref->refcount, 1);
93 1272103 ref->opaque = opaque;
94 1272103 ref->free_cb = free_cb;
95 1272103 ref->free = av_free;
96
97 #if REFSTRUCT_CHECKED
98 ref->cookie = REFSTRUCT_COOKIE;
99 #endif
100 1272103 }
101
102 1272103 void *av_refstruct_alloc_ext_c(size_t size, unsigned flags, AVRefStructOpaque opaque,
103 void (*free_cb)(AVRefStructOpaque opaque, void *obj))
104 {
105 void *buf, *obj;
106
107
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 1272103 if (size > SIZE_MAX - REFCOUNT_OFFSET)
108 ✗ return NULL;
109 1272103 buf = av_malloc(size + REFCOUNT_OFFSET);
110
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 1272103 if (!buf)
111 ✗ return NULL;
112 1272103 refcount_init(buf, opaque, free_cb);
113 1272103 obj = get_userdata(buf);
114
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 1272103 if (!(flags & AV_REFSTRUCT_FLAG_NO_ZEROING))
115 1268290 memset(obj, 0, size);
116
117 1272103 return obj;
118 }
119
120 17694980 void av_refstruct_unref(void *objp)
121 {
122 void *obj;
123 RefCount *ref;
124
125 17694980 memcpy(&obj, objp, sizeof(obj));
126
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 17694980 if (!obj)
127 11501519 return;
128 6193461 memcpy(objp, &(void *){ NULL }, sizeof(obj));
129
130 6193461 ref = get_refcount(obj);
131
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 6193461 if (atomic_fetch_sub_explicit(&ref->refcount, 1, memory_order_acq_rel) == 1) {
132
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 5686987 if (ref->free_cb)
133 2359627 ref->free_cb(ref->opaque, obj);
134 5686987 ref->free(ref);
135 }
136
137 6193461 return;
138 }
139
140 42734 void *av_refstruct_ref(void *obj)
141 {
142 42734 RefCount *ref = get_refcount(obj);
143
144 42734 atomic_fetch_add_explicit(&ref->refcount, 1, memory_order_relaxed);
145
146 42734 return obj;
147 }
148
149 463740 const void *av_refstruct_ref_c(const void *obj)
150 {
151 /* Casting const away here is fine, as it is only supposed
152 * to apply to the user's data and not our bookkeeping data. */
153 463740 RefCount *ref = get_refcount((void*)obj);
154
155 463740 atomic_fetch_add_explicit(&ref->refcount, 1, memory_order_relaxed);
156
157 463740 return obj;
158 }
159
160 1642280 void av_refstruct_replace(void *dstp, const void *src)
161 {
162 const void *dst;
163 1642280 memcpy(&dst, dstp, sizeof(dst));
164
165
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 1642280 if (src == dst)
166 1236212 return;
167 406068 av_refstruct_unref(dstp);
168
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 406068 if (src) {
169 406068 dst = av_refstruct_ref_c(src);
170 406068 memcpy(dstp, &dst, sizeof(dst));
171 }
172 }
173
174 306 int av_refstruct_exclusive(const void *obj)
175 {
176 306 const RefCount *ref = cget_refcount(obj);
177 /* Casting const away here is safe, because it is a load.
178 * It is necessary because atomic_load_explicit() does not
179 * accept const atomics in C11 (see also N1807). */
180 306 return atomic_load_explicit((atomic_uintptr_t*)&ref->refcount, memory_order_acquire) == 1;
181 }
182
183 struct AVRefStructPool {
184 size_t size;
185 AVRefStructOpaque opaque;
186 int (*init_cb)(AVRefStructOpaque opaque, void *obj);
187 void (*reset_cb)(AVRefStructOpaque opaque, void *obj);
188 void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj);
189 void (*free_cb)(AVRefStructOpaque opaque);
190
191 int uninited;
192 unsigned entry_flags;
193 unsigned pool_flags;
194
195 /** The number of outstanding entries not in available_entries. */
196 atomic_uintptr_t refcount;
197 /**
198 * This is a linked list of available entries;
199 * the RefCount's opaque pointer is used as next pointer
200 * for available entries.
201 * While the entries are in use, the opaque is a pointer
202 * to the corresponding AVRefStructPool.
203 */
204 RefCount *available_entries;
205 AVMutex mutex;
206 };
207
208 46418 static void pool_free(AVRefStructPool *pool)
209 {
210 46418 ff_mutex_destroy(&pool->mutex);
211
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 46418 if (pool->free_cb)
212 ✗ pool->free_cb(pool->opaque);
213 46418 av_free(get_refcount(pool));
214 46418 }
215
216 730556 static void pool_free_entry(AVRefStructPool *pool, RefCount *ref)
217 {
218
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 730556 if (pool->free_entry_cb)
219 141933 pool->free_entry_cb(pool->opaque, get_userdata(ref));
220 730556 av_free(ref);
221 730556 }
222
223 5145440 static void pool_return_entry(void *ref_)
224 {
225 5145440 RefCount *ref = ref_;
226 5145440 AVRefStructPool *pool = ref->opaque.nc;
227
228 5145440 ff_mutex_lock(&pool->mutex);
229
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 5145440 if (!pool->uninited) {
230 5125110 ref->opaque.nc = pool->available_entries;
231 5125110 pool->available_entries = ref;
232 5125110 ref = NULL;
233 }
234 5145440 ff_mutex_unlock(&pool->mutex);
235
236
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 5145440 if (ref)
237 20330 pool_free_entry(pool, ref);
238
239
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 5145440 if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
240 5495 pool_free(pool);
241 5145440 }
242
243 1839703 static void pool_reset_entry(AVRefStructOpaque opaque, void *entry)
244 {
245 1839703 AVRefStructPool *pool = opaque.nc;
246
247 1839703 pool->reset_cb(pool->opaque, entry);
248 1839703 }
249
250 5145440 static int refstruct_pool_get_ext(void *datap, AVRefStructPool *pool)
251 {
252 5145440 void *ret = NULL;
253
254 5145440 memcpy(datap, &(void *){ NULL }, sizeof(void*));
255
256 5145440 ff_mutex_lock(&pool->mutex);
257 ff_assert(!pool->uninited);
258
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 5145440 if (pool->available_entries) {
259 4414884 RefCount *ref = pool->available_entries;
260 4414884 ret = get_userdata(ref);
261 4414884 pool->available_entries = ref->opaque.nc;
262 4414884 ref->opaque.nc = pool;
263 4414884 atomic_init(&ref->refcount, 1);
264 }
265 5145440 ff_mutex_unlock(&pool->mutex);
266
267
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 5145440 if (!ret) {
268 RefCount *ref;
269 730556 ret = av_refstruct_alloc_ext(pool->size, pool->entry_flags, pool,
270
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 730556 pool->reset_cb ? pool_reset_entry : NULL);
271
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 730556 if (!ret)
272 ✗ return AVERROR(ENOMEM);
273 730556 ref = get_refcount(ret);
274 730556 ref->free = pool_return_entry;
275
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 730556 if (pool->init_cb) {
276 141933 int err = pool->init_cb(pool->opaque, ret);
277
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 141933 if (err < 0) {
278 ✗ if (pool->pool_flags & AV_REFSTRUCT_POOL_FLAG_RESET_ON_INIT_ERROR)
279 ✗ pool->reset_cb(pool->opaque, ret);
280 ✗ if (pool->pool_flags & AV_REFSTRUCT_POOL_FLAG_FREE_ON_INIT_ERROR)
281 ✗ pool->free_entry_cb(pool->opaque, ret);
282 ✗ av_free(ref);
283 ✗ return err;
284 }
285 }
286 }
287 5145440 atomic_fetch_add_explicit(&pool->refcount, 1, memory_order_relaxed);
288
289
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 5145440 if (pool->pool_flags & AV_REFSTRUCT_POOL_FLAG_ZERO_EVERY_TIME)
290 41412 memset(ret, 0, pool->size);
291
292 5145440 memcpy(datap, &ret, sizeof(ret));
293
294 5145440 return 0;
295 }
296
297 5145440 void *av_refstruct_pool_get(AVRefStructPool *pool)
298 {
299 void *ret;
300 5145440 refstruct_pool_get_ext(&ret, pool);
301 5145440 return ret;
302 }
303
304 /**
305 * Hint: The content of pool_unref() and refstruct_pool_uninit()
306 * could currently be merged; they are only separate functions
307 * in case we would ever introduce weak references.
308 */
309 46418 static void pool_unref(void *ref)
310 {
311 46418 AVRefStructPool *pool = get_userdata(ref);
312
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 46418 if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
313 40923 pool_free(pool);
314 46418 }
315
316 46418 static void refstruct_pool_uninit(AVRefStructOpaque unused, void *obj)
317 {
318 46418 AVRefStructPool *pool = obj;
319 RefCount *entry;
320
321 46418 ff_mutex_lock(&pool->mutex);
322 ff_assert(!pool->uninited);
323 46418 pool->uninited = 1;
324 46418 entry = pool->available_entries;
325 46418 pool->available_entries = NULL;
326 46418 ff_mutex_unlock(&pool->mutex);
327
328
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 756644 while (entry) {
329 710226 void *next = entry->opaque.nc;
330 710226 pool_free_entry(pool, entry);
331 710226 entry = next;
332 }
333 46418 }
334
335 9001 AVRefStructPool *av_refstruct_pool_alloc(size_t size, unsigned flags)
336 {
337 9001 return av_refstruct_pool_alloc_ext(size, flags, NULL, NULL, NULL, NULL, NULL);
338 }
339
340 46418 AVRefStructPool *av_refstruct_pool_alloc_ext_c(size_t size, unsigned flags,
341 AVRefStructOpaque opaque,
342 int (*init_cb)(AVRefStructOpaque opaque, void *obj),
343 void (*reset_cb)(AVRefStructOpaque opaque, void *obj),
344 void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj),
345 void (*free_cb)(AVRefStructOpaque opaque))
346 {
347 46418 AVRefStructPool *pool = av_refstruct_alloc_ext(sizeof(*pool), 0, NULL,
348 refstruct_pool_uninit);
349 int err;
350
351
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 46418 if (!pool)
352 ✗ return NULL;
353 46418 get_refcount(pool)->free = pool_unref;
354
355 46418 pool->size = size;
356 46418 pool->opaque = opaque;
357 46418 pool->init_cb = init_cb;
358 46418 pool->reset_cb = reset_cb;
359 46418 pool->free_entry_cb = free_entry_cb;
360 46418 pool->free_cb = free_cb;
361 #define COMMON_FLAGS AV_REFSTRUCT_POOL_FLAG_NO_ZEROING
362 46418 pool->entry_flags = flags & COMMON_FLAGS;
363 // Filter out nonsense combinations to avoid checks later.
364
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 46418 if (!pool->reset_cb)
365 9001 flags &= ~AV_REFSTRUCT_POOL_FLAG_RESET_ON_INIT_ERROR;
366
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 46418 if (!pool->free_entry_cb)
367 9001 flags &= ~AV_REFSTRUCT_POOL_FLAG_FREE_ON_INIT_ERROR;
368 46418 pool->pool_flags = flags;
369
370
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 46418 if (flags & AV_REFSTRUCT_POOL_FLAG_ZERO_EVERY_TIME) {
371 // We will zero the buffer before every use, so zeroing
372 // upon allocating the buffer is unnecessary.
373 1557 pool->entry_flags |= AV_REFSTRUCT_FLAG_NO_ZEROING;
374 }
375
376 46418 atomic_init(&pool->refcount, 1);
377
378 46418 err = ff_mutex_init(&pool->mutex, NULL);
379
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 46418 if (err) {
380 // Don't call av_refstruct_uninit() on pool, as it hasn't been properly
381 // set up and is just a POD right now.
382 ✗ av_free(get_refcount(pool));
383 ✗ return NULL;
384 }
385 46418 return pool;
386 }
387