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mem.c
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1 /*
2  * default memory allocator for libavutil
3  * Copyright (c) 2002 Fabrice Bellard
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * default memory allocator for libavutil
25  */
26 
27 #define _XOPEN_SOURCE 600
28 
29 #include "config.h"
30 
31 #include <limits.h>
32 #include <stdint.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #if HAVE_MALLOC_H
36 #include <malloc.h>
37 #endif
38 
39 #include "avassert.h"
40 #include "avutil.h"
41 #include "common.h"
42 #include "intreadwrite.h"
43 #include "mem.h"
44 
45 #ifdef MALLOC_PREFIX
46 
47 #define malloc AV_JOIN(MALLOC_PREFIX, malloc)
48 #define memalign AV_JOIN(MALLOC_PREFIX, memalign)
49 #define posix_memalign AV_JOIN(MALLOC_PREFIX, posix_memalign)
50 #define realloc AV_JOIN(MALLOC_PREFIX, realloc)
51 #define free AV_JOIN(MALLOC_PREFIX, free)
52 
53 void *malloc(size_t size);
54 void *memalign(size_t align, size_t size);
55 int posix_memalign(void **ptr, size_t align, size_t size);
56 void *realloc(void *ptr, size_t size);
57 void free(void *ptr);
58 
59 #endif /* MALLOC_PREFIX */
60 
61 #define ALIGN (HAVE_AVX ? 32 : 16)
62 
63 /* NOTE: if you want to override these functions with your own
64  * implementations (not recommended) you have to link libav* as
65  * dynamic libraries and remove -Wl,-Bsymbolic from the linker flags.
66  * Note that this will cost performance. */
67 
68 static size_t max_alloc_size= INT_MAX;
69 
70 void av_max_alloc(size_t max){
71  max_alloc_size = max;
72 }
73 
74 void *av_malloc(size_t size)
75 {
76  void *ptr = NULL;
77 #if CONFIG_MEMALIGN_HACK
78  long diff;
79 #endif
80 
81  /* let's disallow possibly ambiguous cases */
82  if (size > (max_alloc_size - 32))
83  return NULL;
84 
85 #if CONFIG_MEMALIGN_HACK
86  ptr = malloc(size + ALIGN);
87  if (!ptr)
88  return ptr;
89  diff = ((~(long)ptr)&(ALIGN - 1)) + 1;
90  ptr = (char *)ptr + diff;
91  ((char *)ptr)[-1] = diff;
92 #elif HAVE_POSIX_MEMALIGN
93  if (size) //OS X on SDK 10.6 has a broken posix_memalign implementation
94  if (posix_memalign(&ptr, ALIGN, size))
95  ptr = NULL;
96 #elif HAVE_ALIGNED_MALLOC
97  ptr = _aligned_malloc(size, ALIGN);
98 #elif HAVE_MEMALIGN
99 #ifndef __DJGPP__
100  ptr = memalign(ALIGN, size);
101 #else
102  ptr = memalign(size, ALIGN);
103 #endif
104  /* Why 64?
105  * Indeed, we should align it:
106  * on 4 for 386
107  * on 16 for 486
108  * on 32 for 586, PPro - K6-III
109  * on 64 for K7 (maybe for P3 too).
110  * Because L1 and L2 caches are aligned on those values.
111  * But I don't want to code such logic here!
112  */
113  /* Why 32?
114  * For AVX ASM. SSE / NEON needs only 16.
115  * Why not larger? Because I did not see a difference in benchmarks ...
116  */
117  /* benchmarks with P3
118  * memalign(64) + 1 3071, 3051, 3032
119  * memalign(64) + 2 3051, 3032, 3041
120  * memalign(64) + 4 2911, 2896, 2915
121  * memalign(64) + 8 2545, 2554, 2550
122  * memalign(64) + 16 2543, 2572, 2563
123  * memalign(64) + 32 2546, 2545, 2571
124  * memalign(64) + 64 2570, 2533, 2558
125  *
126  * BTW, malloc seems to do 8-byte alignment by default here.
127  */
128 #else
129  ptr = malloc(size);
130 #endif
131  if(!ptr && !size) {
132  size = 1;
133  ptr= av_malloc(1);
134  }
135 #if CONFIG_MEMORY_POISONING
136  if (ptr)
137  memset(ptr, FF_MEMORY_POISON, size);
138 #endif
139  return ptr;
140 }
141 
142 void *av_realloc(void *ptr, size_t size)
143 {
144 #if CONFIG_MEMALIGN_HACK
145  int diff;
146 #endif
147 
148  /* let's disallow possibly ambiguous cases */
149  if (size > (max_alloc_size - 32))
150  return NULL;
151 
152 #if CONFIG_MEMALIGN_HACK
153  //FIXME this isn't aligned correctly, though it probably isn't needed
154  if (!ptr)
155  return av_malloc(size);
156  diff = ((char *)ptr)[-1];
157  av_assert0(diff>0 && diff<=ALIGN);
158  ptr = realloc((char *)ptr - diff, size + diff);
159  if (ptr)
160  ptr = (char *)ptr + diff;
161  return ptr;
162 #elif HAVE_ALIGNED_MALLOC
163  return _aligned_realloc(ptr, size + !size, ALIGN);
164 #else
165  return realloc(ptr, size + !size);
166 #endif
167 }
168 
169 void *av_realloc_f(void *ptr, size_t nelem, size_t elsize)
170 {
171  size_t size;
172  void *r;
173 
174  if (av_size_mult(elsize, nelem, &size)) {
175  av_free(ptr);
176  return NULL;
177  }
178  r = av_realloc(ptr, size);
179  if (!r && size)
180  av_free(ptr);
181  return r;
182 }
183 
184 int av_reallocp(void *ptr, size_t size)
185 {
186  void **ptrptr = ptr;
187  void *ret;
188 
189  if (!size) {
190  av_freep(ptr);
191  return 0;
192  }
193  ret = av_realloc(*ptrptr, size);
194 
195  if (!ret) {
196  av_freep(ptr);
197  return AVERROR(ENOMEM);
198  }
199 
200  *ptrptr = ret;
201  return 0;
202 }
203 
204 void *av_realloc_array(void *ptr, size_t nmemb, size_t size)
205 {
206  if (!size || nmemb >= INT_MAX / size)
207  return NULL;
208  return av_realloc(ptr, nmemb * size);
209 }
210 
211 int av_reallocp_array(void *ptr, size_t nmemb, size_t size)
212 {
213  void **ptrptr = ptr;
214  *ptrptr = av_realloc_f(*ptrptr, nmemb, size);
215  if (!*ptrptr && nmemb && size)
216  return AVERROR(ENOMEM);
217  return 0;
218 }
219 
220 void av_free(void *ptr)
221 {
222 #if CONFIG_MEMALIGN_HACK
223  if (ptr) {
224  int v= ((char *)ptr)[-1];
225  av_assert0(v>0 && v<=ALIGN);
226  free((char *)ptr - v);
227  }
228 #elif HAVE_ALIGNED_MALLOC
229  _aligned_free(ptr);
230 #else
231  free(ptr);
232 #endif
233 }
234 
235 void av_freep(void *arg)
236 {
237  void **ptr = (void **)arg;
238  av_free(*ptr);
239  *ptr = NULL;
240 }
241 
242 void *av_mallocz(size_t size)
243 {
244  void *ptr = av_malloc(size);
245  if (ptr)
246  memset(ptr, 0, size);
247  return ptr;
248 }
249 
250 void *av_calloc(size_t nmemb, size_t size)
251 {
252  if (size <= 0 || nmemb >= INT_MAX / size)
253  return NULL;
254  return av_mallocz(nmemb * size);
255 }
256 
257 char *av_strdup(const char *s)
258 {
259  char *ptr = NULL;
260  if (s) {
261  int len = strlen(s) + 1;
262  ptr = av_realloc(NULL, len);
263  if (ptr)
264  memcpy(ptr, s, len);
265  }
266  return ptr;
267 }
268 
269 void *av_memdup(const void *p, size_t size)
270 {
271  void *ptr = NULL;
272  if (p) {
273  ptr = av_malloc(size);
274  if (ptr)
275  memcpy(ptr, p, size);
276  }
277  return ptr;
278 }
279 
280 void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem)
281 {
282  /* see similar ffmpeg.c:grow_array() */
283  int nb, nb_alloc;
284  intptr_t *tab;
285 
286  nb = *nb_ptr;
287  tab = *(intptr_t**)tab_ptr;
288  if ((nb & (nb - 1)) == 0) {
289  if (nb == 0) {
290  nb_alloc = 1;
291  } else {
292  if (nb > INT_MAX / (2 * sizeof(intptr_t)))
293  goto fail;
294  nb_alloc = nb * 2;
295  }
296  tab = av_realloc(tab, nb_alloc * sizeof(intptr_t));
297  if (!tab)
298  goto fail;
299  *(intptr_t**)tab_ptr = tab;
300  }
301  tab[nb++] = (intptr_t)elem;
302  *nb_ptr = nb;
303  return;
304 
305 fail:
306  av_freep(tab_ptr);
307  *nb_ptr = 0;
308 }
309 
310 void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
311  const uint8_t *elem_data)
312 {
313  int nb = *nb_ptr, nb_alloc;
314  uint8_t *tab = *tab_ptr, *tab_elem_data;
315 
316  if ((nb & (nb - 1)) == 0) {
317  if (nb == 0) {
318  nb_alloc = 1;
319  } else {
320  if (nb > INT_MAX / (2 * elem_size))
321  goto fail;
322  nb_alloc = nb * 2;
323  }
324  tab = av_realloc(tab, nb_alloc * elem_size);
325  if (!tab)
326  goto fail;
327  *tab_ptr = tab;
328  }
329  *nb_ptr = nb + 1;
330  tab_elem_data = tab + nb*elem_size;
331  if (elem_data)
332  memcpy(tab_elem_data, elem_data, elem_size);
333  else if (CONFIG_MEMORY_POISONING)
334  memset(tab_elem_data, FF_MEMORY_POISON, elem_size);
335  return tab_elem_data;
336 
337 fail:
338  av_freep(tab_ptr);
339  *nb_ptr = 0;
340  return NULL;
341 }
342 
343 static void fill16(uint8_t *dst, int len)
344 {
345  uint32_t v = AV_RN16(dst - 2);
346 
347  v |= v << 16;
348 
349  while (len >= 4) {
350  AV_WN32(dst, v);
351  dst += 4;
352  len -= 4;
353  }
354 
355  while (len--) {
356  *dst = dst[-2];
357  dst++;
358  }
359 }
360 
361 static void fill24(uint8_t *dst, int len)
362 {
363 #if HAVE_BIGENDIAN
364  uint32_t v = AV_RB24(dst - 3);
365  uint32_t a = v << 8 | v >> 16;
366  uint32_t b = v << 16 | v >> 8;
367  uint32_t c = v << 24 | v;
368 #else
369  uint32_t v = AV_RL24(dst - 3);
370  uint32_t a = v | v << 24;
371  uint32_t b = v >> 8 | v << 16;
372  uint32_t c = v >> 16 | v << 8;
373 #endif
374 
375  while (len >= 12) {
376  AV_WN32(dst, a);
377  AV_WN32(dst + 4, b);
378  AV_WN32(dst + 8, c);
379  dst += 12;
380  len -= 12;
381  }
382 
383  if (len >= 4) {
384  AV_WN32(dst, a);
385  dst += 4;
386  len -= 4;
387  }
388 
389  if (len >= 4) {
390  AV_WN32(dst, b);
391  dst += 4;
392  len -= 4;
393  }
394 
395  while (len--) {
396  *dst = dst[-3];
397  dst++;
398  }
399 }
400 
401 static void fill32(uint8_t *dst, int len)
402 {
403  uint32_t v = AV_RN32(dst - 4);
404 
405  while (len >= 4) {
406  AV_WN32(dst, v);
407  dst += 4;
408  len -= 4;
409  }
410 
411  while (len--) {
412  *dst = dst[-4];
413  dst++;
414  }
415 }
416 
417 void av_memcpy_backptr(uint8_t *dst, int back, int cnt)
418 {
419  const uint8_t *src = &dst[-back];
420  if (!back)
421  return;
422 
423  if (back == 1) {
424  memset(dst, *src, cnt);
425  } else if (back == 2) {
426  fill16(dst, cnt);
427  } else if (back == 3) {
428  fill24(dst, cnt);
429  } else if (back == 4) {
430  fill32(dst, cnt);
431  } else {
432  if (cnt >= 16) {
433  int blocklen = back;
434  while (cnt > blocklen) {
435  memcpy(dst, src, blocklen);
436  dst += blocklen;
437  cnt -= blocklen;
438  blocklen <<= 1;
439  }
440  memcpy(dst, src, cnt);
441  return;
442  }
443  if (cnt >= 8) {
444  AV_COPY32U(dst, src);
445  AV_COPY32U(dst + 4, src + 4);
446  src += 8;
447  dst += 8;
448  cnt -= 8;
449  }
450  if (cnt >= 4) {
451  AV_COPY32U(dst, src);
452  src += 4;
453  dst += 4;
454  cnt -= 4;
455  }
456  if (cnt >= 2) {
457  AV_COPY16U(dst, src);
458  src += 2;
459  dst += 2;
460  cnt -= 2;
461  }
462  if (cnt)
463  *dst = *src;
464  }
465 }
466 
467 void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
468 {
469  if (min_size < *size)
470  return ptr;
471 
472  min_size = FFMAX(17 * min_size / 16 + 32, min_size);
473 
474  ptr = av_realloc(ptr, min_size);
475  /* we could set this to the unmodified min_size but this is safer
476  * if the user lost the ptr and uses NULL now
477  */
478  if (!ptr)
479  min_size = 0;
480 
481  *size = min_size;
482 
483  return ptr;
484 }
485 
486 static inline int ff_fast_malloc(void *ptr, unsigned int *size, size_t min_size, int zero_realloc)
487 {
488  void **p = ptr;
489  if (min_size < *size)
490  return 0;
491  min_size = FFMAX(17 * min_size / 16 + 32, min_size);
492  av_free(*p);
493  *p = zero_realloc ? av_mallocz(min_size) : av_malloc(min_size);
494  if (!*p)
495  min_size = 0;
496  *size = min_size;
497  return 1;
498 }
499 
500 void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size)
501 {
502  ff_fast_malloc(ptr, size, min_size, 0);
503 }
504