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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 "dynarray.h"
43 #include "intreadwrite.h"
44 #include "mem.h"
45 
46 #ifdef MALLOC_PREFIX
47 
48 #define malloc AV_JOIN(MALLOC_PREFIX, malloc)
49 #define memalign AV_JOIN(MALLOC_PREFIX, memalign)
50 #define posix_memalign AV_JOIN(MALLOC_PREFIX, posix_memalign)
51 #define realloc AV_JOIN(MALLOC_PREFIX, realloc)
52 #define free AV_JOIN(MALLOC_PREFIX, free)
53 
54 void *malloc(size_t size);
55 void *memalign(size_t align, size_t size);
56 int posix_memalign(void **ptr, size_t align, size_t size);
57 void *realloc(void *ptr, size_t size);
58 void free(void *ptr);
59 
60 #endif /* MALLOC_PREFIX */
61 
62 #define ALIGN (HAVE_AVX ? 32 : 16)
63 
64 /* NOTE: if you want to override these functions with your own
65  * implementations (not recommended) you have to link libav* as
66  * dynamic libraries and remove -Wl,-Bsymbolic from the linker flags.
67  * Note that this will cost performance. */
68 
69 static size_t max_alloc_size= INT_MAX;
70 
71 void av_max_alloc(size_t max){
72  max_alloc_size = max;
73 }
74 
75 void *av_malloc(size_t size)
76 {
77  void *ptr = NULL;
78 #if CONFIG_MEMALIGN_HACK
79  long diff;
80 #endif
81 
82  /* let's disallow possibly ambiguous cases */
83  if (size > (max_alloc_size - 32))
84  return NULL;
85 
86 #if CONFIG_MEMALIGN_HACK
87  ptr = malloc(size + ALIGN);
88  if (!ptr)
89  return ptr;
90  diff = ((~(long)ptr)&(ALIGN - 1)) + 1;
91  ptr = (char *)ptr + diff;
92  ((char *)ptr)[-1] = diff;
93 #elif HAVE_POSIX_MEMALIGN
94  if (size) //OS X on SDK 10.6 has a broken posix_memalign implementation
95  if (posix_memalign(&ptr, ALIGN, size))
96  ptr = NULL;
97 #elif HAVE_ALIGNED_MALLOC
98  ptr = _aligned_malloc(size, ALIGN);
99 #elif HAVE_MEMALIGN
100 #ifndef __DJGPP__
101  ptr = memalign(ALIGN, size);
102 #else
103  ptr = memalign(size, ALIGN);
104 #endif
105  /* Why 64?
106  * Indeed, we should align it:
107  * on 4 for 386
108  * on 16 for 486
109  * on 32 for 586, PPro - K6-III
110  * on 64 for K7 (maybe for P3 too).
111  * Because L1 and L2 caches are aligned on those values.
112  * But I don't want to code such logic here!
113  */
114  /* Why 32?
115  * For AVX ASM. SSE / NEON needs only 16.
116  * Why not larger? Because I did not see a difference in benchmarks ...
117  */
118  /* benchmarks with P3
119  * memalign(64) + 1 3071, 3051, 3032
120  * memalign(64) + 2 3051, 3032, 3041
121  * memalign(64) + 4 2911, 2896, 2915
122  * memalign(64) + 8 2545, 2554, 2550
123  * memalign(64) + 16 2543, 2572, 2563
124  * memalign(64) + 32 2546, 2545, 2571
125  * memalign(64) + 64 2570, 2533, 2558
126  *
127  * BTW, malloc seems to do 8-byte alignment by default here.
128  */
129 #else
130  ptr = malloc(size);
131 #endif
132  if(!ptr && !size) {
133  size = 1;
134  ptr= av_malloc(1);
135  }
136 #if CONFIG_MEMORY_POISONING
137  if (ptr)
138  memset(ptr, FF_MEMORY_POISON, size);
139 #endif
140  return ptr;
141 }
142 
143 void *av_realloc(void *ptr, size_t size)
144 {
145 #if CONFIG_MEMALIGN_HACK
146  int diff;
147 #endif
148 
149  /* let's disallow possibly ambiguous cases */
150  if (size > (max_alloc_size - 32))
151  return NULL;
152 
153 #if CONFIG_MEMALIGN_HACK
154  //FIXME this isn't aligned correctly, though it probably isn't needed
155  if (!ptr)
156  return av_malloc(size);
157  diff = ((char *)ptr)[-1];
158  av_assert0(diff>0 && diff<=ALIGN);
159  ptr = realloc((char *)ptr - diff, size + diff);
160  if (ptr)
161  ptr = (char *)ptr + diff;
162  return ptr;
163 #elif HAVE_ALIGNED_MALLOC
164  return _aligned_realloc(ptr, size + !size, ALIGN);
165 #else
166  return realloc(ptr, size + !size);
167 #endif
168 }
169 
170 void *av_realloc_f(void *ptr, size_t nelem, size_t elsize)
171 {
172  size_t size;
173  void *r;
174 
175  if (av_size_mult(elsize, nelem, &size)) {
176  av_free(ptr);
177  return NULL;
178  }
179  r = av_realloc(ptr, size);
180  if (!r && size)
181  av_free(ptr);
182  return r;
183 }
184 
185 int av_reallocp(void *ptr, size_t size)
186 {
187  void **ptrptr = ptr;
188  void *ret;
189 
190  if (!size) {
191  av_freep(ptr);
192  return 0;
193  }
194  ret = av_realloc(*ptrptr, size);
195 
196  if (!ret) {
197  av_freep(ptr);
198  return AVERROR(ENOMEM);
199  }
200 
201  *ptrptr = ret;
202  return 0;
203 }
204 
205 void *av_realloc_array(void *ptr, size_t nmemb, size_t size)
206 {
207  if (!size || nmemb >= INT_MAX / size)
208  return NULL;
209  return av_realloc(ptr, nmemb * size);
210 }
211 
212 int av_reallocp_array(void *ptr, size_t nmemb, size_t size)
213 {
214  void **ptrptr = ptr;
215  *ptrptr = av_realloc_f(*ptrptr, nmemb, size);
216  if (!*ptrptr && nmemb && size)
217  return AVERROR(ENOMEM);
218  return 0;
219 }
220 
221 void av_free(void *ptr)
222 {
223 #if CONFIG_MEMALIGN_HACK
224  if (ptr) {
225  int v= ((char *)ptr)[-1];
226  av_assert0(v>0 && v<=ALIGN);
227  free((char *)ptr - v);
228  }
229 #elif HAVE_ALIGNED_MALLOC
230  _aligned_free(ptr);
231 #else
232  free(ptr);
233 #endif
234 }
235 
236 void av_freep(void *arg)
237 {
238  void **ptr = (void **)arg;
239  av_free(*ptr);
240  *ptr = NULL;
241 }
242 
243 void *av_mallocz(size_t size)
244 {
245  void *ptr = av_malloc(size);
246  if (ptr)
247  memset(ptr, 0, size);
248  return ptr;
249 }
250 
251 void *av_calloc(size_t nmemb, size_t size)
252 {
253  if (size <= 0 || nmemb >= INT_MAX / size)
254  return NULL;
255  return av_mallocz(nmemb * size);
256 }
257 
258 char *av_strdup(const char *s)
259 {
260  char *ptr = NULL;
261  if (s) {
262  int len = strlen(s) + 1;
263  ptr = av_realloc(NULL, len);
264  if (ptr)
265  memcpy(ptr, s, len);
266  }
267  return ptr;
268 }
269 
270 char *av_strndup(const char *s, size_t len)
271 {
272  char *ret = NULL, *end;
273 
274  if (!s)
275  return NULL;
276 
277  end = memchr(s, 0, len);
278  if (end)
279  len = end - s;
280 
281  ret = av_realloc(NULL, len + 1);
282  if (!ret)
283  return NULL;
284 
285  memcpy(ret, s, len);
286  ret[len] = 0;
287  return ret;
288 }
289 
290 void *av_memdup(const void *p, size_t size)
291 {
292  void *ptr = NULL;
293  if (p) {
294  ptr = av_malloc(size);
295  if (ptr)
296  memcpy(ptr, p, size);
297  }
298  return ptr;
299 }
300 
301 int av_dynarray_add_nofree(void *tab_ptr, int *nb_ptr, void *elem)
302 {
303  void **tab = *(void ***)tab_ptr;
304 
305  AV_DYNARRAY_ADD(INT_MAX, sizeof(*tab), tab, *nb_ptr, {
306  tab[*nb_ptr] = elem;
307  *(void ***)tab_ptr = tab;
308  }, {
309  return AVERROR(ENOMEM);
310  });
311  return 0;
312 }
313 
314 void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem)
315 {
316  void **tab = *(void ***)tab_ptr;
317 
318  AV_DYNARRAY_ADD(INT_MAX, sizeof(*tab), tab, *nb_ptr, {
319  tab[*nb_ptr] = elem;
320  *(void ***)tab_ptr = tab;
321  }, {
322  *nb_ptr = 0;
323  av_freep(tab_ptr);
324  });
325 }
326 
327 void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
328  const uint8_t *elem_data)
329 {
330  uint8_t *tab_elem_data = NULL;
331 
332  AV_DYNARRAY_ADD(INT_MAX, elem_size, *tab_ptr, *nb_ptr, {
333  tab_elem_data = (uint8_t *)*tab_ptr + (*nb_ptr) * elem_size;
334  if (elem_data)
335  memcpy(tab_elem_data, elem_data, elem_size);
336  else if (CONFIG_MEMORY_POISONING)
337  memset(tab_elem_data, FF_MEMORY_POISON, elem_size);
338  }, {
339  av_freep(tab_ptr);
340  *nb_ptr = 0;
341  });
342  return tab_elem_data;
343 }
344 
345 static void fill16(uint8_t *dst, int len)
346 {
347  uint32_t v = AV_RN16(dst - 2);
348 
349  v |= v << 16;
350 
351  while (len >= 4) {
352  AV_WN32(dst, v);
353  dst += 4;
354  len -= 4;
355  }
356 
357  while (len--) {
358  *dst = dst[-2];
359  dst++;
360  }
361 }
362 
363 static void fill24(uint8_t *dst, int len)
364 {
365 #if HAVE_BIGENDIAN
366  uint32_t v = AV_RB24(dst - 3);
367  uint32_t a = v << 8 | v >> 16;
368  uint32_t b = v << 16 | v >> 8;
369  uint32_t c = v << 24 | v;
370 #else
371  uint32_t v = AV_RL24(dst - 3);
372  uint32_t a = v | v << 24;
373  uint32_t b = v >> 8 | v << 16;
374  uint32_t c = v >> 16 | v << 8;
375 #endif
376 
377  while (len >= 12) {
378  AV_WN32(dst, a);
379  AV_WN32(dst + 4, b);
380  AV_WN32(dst + 8, c);
381  dst += 12;
382  len -= 12;
383  }
384 
385  if (len >= 4) {
386  AV_WN32(dst, a);
387  dst += 4;
388  len -= 4;
389  }
390 
391  if (len >= 4) {
392  AV_WN32(dst, b);
393  dst += 4;
394  len -= 4;
395  }
396 
397  while (len--) {
398  *dst = dst[-3];
399  dst++;
400  }
401 }
402 
403 static void fill32(uint8_t *dst, int len)
404 {
405  uint32_t v = AV_RN32(dst - 4);
406 
407  while (len >= 4) {
408  AV_WN32(dst, v);
409  dst += 4;
410  len -= 4;
411  }
412 
413  while (len--) {
414  *dst = dst[-4];
415  dst++;
416  }
417 }
418 
419 void av_memcpy_backptr(uint8_t *dst, int back, int cnt)
420 {
421  const uint8_t *src = &dst[-back];
422  if (!back)
423  return;
424 
425  if (back == 1) {
426  memset(dst, *src, cnt);
427  } else if (back == 2) {
428  fill16(dst, cnt);
429  } else if (back == 3) {
430  fill24(dst, cnt);
431  } else if (back == 4) {
432  fill32(dst, cnt);
433  } else {
434  if (cnt >= 16) {
435  int blocklen = back;
436  while (cnt > blocklen) {
437  memcpy(dst, src, blocklen);
438  dst += blocklen;
439  cnt -= blocklen;
440  blocklen <<= 1;
441  }
442  memcpy(dst, src, cnt);
443  return;
444  }
445  if (cnt >= 8) {
446  AV_COPY32U(dst, src);
447  AV_COPY32U(dst + 4, src + 4);
448  src += 8;
449  dst += 8;
450  cnt -= 8;
451  }
452  if (cnt >= 4) {
453  AV_COPY32U(dst, src);
454  src += 4;
455  dst += 4;
456  cnt -= 4;
457  }
458  if (cnt >= 2) {
459  AV_COPY16U(dst, src);
460  src += 2;
461  dst += 2;
462  cnt -= 2;
463  }
464  if (cnt)
465  *dst = *src;
466  }
467 }
468 
469 void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
470 {
471  if (min_size < *size)
472  return ptr;
473 
474  min_size = FFMAX(17 * min_size / 16 + 32, min_size);
475 
476  ptr = av_realloc(ptr, min_size);
477  /* we could set this to the unmodified min_size but this is safer
478  * if the user lost the ptr and uses NULL now
479  */
480  if (!ptr)
481  min_size = 0;
482 
483  *size = min_size;
484 
485  return ptr;
486 }
487 
488 static inline int ff_fast_malloc(void *ptr, unsigned int *size, size_t min_size, int zero_realloc)
489 {
490  void **p = ptr;
491  if (min_size < *size)
492  return 0;
493  min_size = FFMAX(17 * min_size / 16 + 32, min_size);
494  av_free(*p);
495  *p = zero_realloc ? av_mallocz(min_size) : av_malloc(min_size);
496  if (!*p)
497  min_size = 0;
498  *size = min_size;
499  return 1;
500 }
501 
502 void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size)
503 {
504  ff_fast_malloc(ptr, size, min_size, 0);
505 }
506