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mem.h
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * memory handling functions
24  */
25 
26 #ifndef AVUTIL_MEM_H
27 #define AVUTIL_MEM_H
28 
29 #include <limits.h>
30 #include <stdint.h>
31 
32 #include "attributes.h"
33 #include "error.h"
34 #include "avutil.h"
35 
36 /**
37  * @addtogroup lavu_mem
38  * @{
39  */
40 
41 
42 #if defined(__INTEL_COMPILER) && __INTEL_COMPILER < 1110 || defined(__SUNPRO_C)
43  #define DECLARE_ALIGNED(n,t,v) t __attribute__ ((aligned (n))) v
44  #define DECLARE_ASM_CONST(n,t,v) const t __attribute__ ((aligned (n))) v
45 #elif defined(__TI_COMPILER_VERSION__)
46  #define DECLARE_ALIGNED(n,t,v) \
47  AV_PRAGMA(DATA_ALIGN(v,n)) \
48  t __attribute__((aligned(n))) v
49  #define DECLARE_ASM_CONST(n,t,v) \
50  AV_PRAGMA(DATA_ALIGN(v,n)) \
51  static const t __attribute__((aligned(n))) v
52 #elif defined(__GNUC__)
53  #define DECLARE_ALIGNED(n,t,v) t __attribute__ ((aligned (n))) v
54  #define DECLARE_ASM_CONST(n,t,v) static const t av_used __attribute__ ((aligned (n))) v
55 #elif defined(_MSC_VER)
56  #define DECLARE_ALIGNED(n,t,v) __declspec(align(n)) t v
57  #define DECLARE_ASM_CONST(n,t,v) __declspec(align(n)) static const t v
58 #else
59  #define DECLARE_ALIGNED(n,t,v) t v
60  #define DECLARE_ASM_CONST(n,t,v) static const t v
61 #endif
62 
63 #if AV_GCC_VERSION_AT_LEAST(3,1)
64  #define av_malloc_attrib __attribute__((__malloc__))
65 #else
66  #define av_malloc_attrib
67 #endif
68 
69 #if AV_GCC_VERSION_AT_LEAST(4,3)
70  #define av_alloc_size(...) __attribute__((alloc_size(__VA_ARGS__)))
71 #else
72  #define av_alloc_size(...)
73 #endif
74 
75 /**
76  * Allocate a block of size bytes with alignment suitable for all
77  * memory accesses (including vectors if available on the CPU).
78  * @param size Size in bytes for the memory block to be allocated.
79  * @return Pointer to the allocated block, NULL if the block cannot
80  * be allocated.
81  * @see av_mallocz()
82  */
84 
85 /**
86  * Allocate a block of size * nmemb bytes with av_malloc().
87  * @param nmemb Number of elements
88  * @param size Size of the single element
89  * @return Pointer to the allocated block, NULL if the block cannot
90  * be allocated.
91  * @see av_malloc()
92  */
93 av_alloc_size(1, 2) static inline void *av_malloc_array(size_t nmemb, size_t size)
94 {
95  if (!size || nmemb >= INT_MAX / size)
96  return NULL;
97  return av_malloc(nmemb * size);
98 }
99 
100 /**
101  * Allocate or reallocate a block of memory.
102  * If ptr is NULL and size > 0, allocate a new block. If
103  * size is zero, free the memory block pointed to by ptr.
104  * @param ptr Pointer to a memory block already allocated with
105  * av_realloc() or NULL.
106  * @param size Size in bytes of the memory block to be allocated or
107  * reallocated.
108  * @return Pointer to a newly-reallocated block or NULL if the block
109  * cannot be reallocated or the function is used to free the memory block.
110  * @warning Pointers originating from the av_malloc() family of functions must
111  * not be passed to av_realloc(). The former can be implemented using
112  * memalign() (or other functions), and there is no guarantee that
113  * pointers from such functions can be passed to realloc() at all.
114  * The situation is undefined according to POSIX and may crash with
115  * some libc implementations.
116  * @see av_fast_realloc()
117  */
118 void *av_realloc(void *ptr, size_t size) av_alloc_size(2);
119 
120 /**
121  * Allocate or reallocate a block of memory.
122  * This function does the same thing as av_realloc, except:
123  * - It takes two arguments and checks the result of the multiplication for
124  * integer overflow.
125  * - It frees the input block in case of failure, thus avoiding the memory
126  * leak with the classic "buf = realloc(buf); if (!buf) return -1;".
127  */
128 void *av_realloc_f(void *ptr, size_t nelem, size_t elsize);
129 
130 /**
131  * Allocate or reallocate a block of memory.
132  * If *ptr is NULL and size > 0, allocate a new block. If
133  * size is zero, free the memory block pointed to by ptr.
134  * @param ptr Pointer to a pointer to a memory block already allocated
135  * with av_realloc(), or pointer to a pointer to NULL.
136  * The pointer is updated on success, or freed on failure.
137  * @param size Size in bytes for the memory block to be allocated or
138  * reallocated
139  * @return Zero on success, an AVERROR error code on failure.
140  * @warning Pointers originating from the av_malloc() family of functions must
141  * not be passed to av_reallocp(). The former can be implemented using
142  * memalign() (or other functions), and there is no guarantee that
143  * pointers from such functions can be passed to realloc() at all.
144  * The situation is undefined according to POSIX and may crash with
145  * some libc implementations.
146  */
147 int av_reallocp(void *ptr, size_t size);
148 
149 /**
150  * Allocate or reallocate an array.
151  * If ptr is NULL and nmemb > 0, allocate a new block. If
152  * nmemb is zero, free the memory block pointed to by ptr.
153  * @param ptr Pointer to a memory block already allocated with
154  * av_realloc() or NULL.
155  * @param nmemb Number of elements
156  * @param size Size of the single element
157  * @return Pointer to a newly-reallocated block or NULL if the block
158  * cannot be reallocated or the function is used to free the memory block.
159  * @warning Pointers originating from the av_malloc() family of functions must
160  * not be passed to av_realloc(). The former can be implemented using
161  * memalign() (or other functions), and there is no guarantee that
162  * pointers from such functions can be passed to realloc() at all.
163  * The situation is undefined according to POSIX and may crash with
164  * some libc implementations.
165  */
166 av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size);
167 
168 /**
169  * Allocate or reallocate an array through a pointer to a pointer.
170  * If *ptr is NULL and nmemb > 0, allocate a new block. If
171  * nmemb is zero, free the memory block pointed to by ptr.
172  * @param ptr Pointer to a pointer to a memory block already allocated
173  * with av_realloc(), or pointer to a pointer to NULL.
174  * The pointer is updated on success, or freed on failure.
175  * @param nmemb Number of elements
176  * @param size Size of the single element
177  * @return Zero on success, an AVERROR error code on failure.
178  * @warning Pointers originating from the av_malloc() family of functions must
179  * not be passed to av_realloc(). The former can be implemented using
180  * memalign() (or other functions), and there is no guarantee that
181  * pointers from such functions can be passed to realloc() at all.
182  * The situation is undefined according to POSIX and may crash with
183  * some libc implementations.
184  */
185 av_alloc_size(2, 3) int av_reallocp_array(void *ptr, size_t nmemb, size_t size);
186 
187 /**
188  * Free a memory block which has been allocated with av_malloc(z)() or
189  * av_realloc().
190  * @param ptr Pointer to the memory block which should be freed.
191  * @note ptr = NULL is explicitly allowed.
192  * @note It is recommended that you use av_freep() instead.
193  * @see av_freep()
194  */
195 void av_free(void *ptr);
196 
197 /**
198  * Allocate a block of size bytes with alignment suitable for all
199  * memory accesses (including vectors if available on the CPU) and
200  * zero all the bytes of the block.
201  * @param size Size in bytes for the memory block to be allocated.
202  * @return Pointer to the allocated block, NULL if it cannot be allocated.
203  * @see av_malloc()
204  */
205 void *av_mallocz(size_t size) av_malloc_attrib av_alloc_size(1);
206 
207 /**
208  * Allocate a block of nmemb * size bytes with alignment suitable for all
209  * memory accesses (including vectors if available on the CPU) and
210  * zero all the bytes of the block.
211  * The allocation will fail if nmemb * size is greater than or equal
212  * to INT_MAX.
213  * @param nmemb
214  * @param size
215  * @return Pointer to the allocated block, NULL if it cannot be allocated.
216  */
217 void *av_calloc(size_t nmemb, size_t size) av_malloc_attrib;
218 
219 /**
220  * Allocate a block of size * nmemb bytes with av_mallocz().
221  * @param nmemb Number of elements
222  * @param size Size of the single element
223  * @return Pointer to the allocated block, NULL if the block cannot
224  * be allocated.
225  * @see av_mallocz()
226  * @see av_malloc_array()
227  */
228 av_alloc_size(1, 2) static inline void *av_mallocz_array(size_t nmemb, size_t size)
229 {
230  if (!size || nmemb >= INT_MAX / size)
231  return NULL;
232  return av_mallocz(nmemb * size);
233 }
234 
235 /**
236  * Duplicate the string s.
237  * @param s string to be duplicated
238  * @return Pointer to a newly-allocated string containing a
239  * copy of s or NULL if the string cannot be allocated.
240  */
241 char *av_strdup(const char *s) av_malloc_attrib;
242 
243 /**
244  * Duplicate the buffer p.
245  * @param p buffer to be duplicated
246  * @return Pointer to a newly allocated buffer containing a
247  * copy of p or NULL if the buffer cannot be allocated.
248  */
249 void *av_memdup(const void *p, size_t size);
250 
251 /**
252  * Free a memory block which has been allocated with av_malloc(z)() or
253  * av_realloc() and set the pointer pointing to it to NULL.
254  * @param ptr Pointer to the pointer to the memory block which should
255  * be freed.
256  * @see av_free()
257  */
258 void av_freep(void *ptr);
259 
260 /**
261  * Add an element to a dynamic array.
262  *
263  * The array to grow is supposed to be an array of pointers to
264  * structures, and the element to add must be a pointer to an already
265  * allocated structure.
266  *
267  * The array is reallocated when its size reaches powers of 2.
268  * Therefore, the amortized cost of adding an element is constant.
269  *
270  * In case of success, the pointer to the array is updated in order to
271  * point to the new grown array, and the number pointed to by nb_ptr
272  * is incremented.
273  * In case of failure, the array is freed, *tab_ptr is set to NULL and
274  * *nb_ptr is set to 0.
275  *
276  * @param tab_ptr pointer to the array to grow
277  * @param nb_ptr pointer to the number of elements in the array
278  * @param elem element to add
279  * @see av_dynarray2_add()
280  */
281 void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem);
282 
283 /**
284  * Add an element of size elem_size to a dynamic array.
285  *
286  * The array is reallocated when its number of elements reaches powers of 2.
287  * Therefore, the amortized cost of adding an element is constant.
288  *
289  * In case of success, the pointer to the array is updated in order to
290  * point to the new grown array, and the number pointed to by nb_ptr
291  * is incremented.
292  * In case of failure, the array is freed, *tab_ptr is set to NULL and
293  * *nb_ptr is set to 0.
294  *
295  * @param tab_ptr pointer to the array to grow
296  * @param nb_ptr pointer to the number of elements in the array
297  * @param elem_size size in bytes of the elements in the array
298  * @param elem_data pointer to the data of the element to add. If NULL, the space of
299  * the new added element is not filled.
300  * @return pointer to the data of the element to copy in the new allocated space.
301  * If NULL, the new allocated space is left uninitialized."
302  * @see av_dynarray_add()
303  */
304 void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
305  const uint8_t *elem_data);
306 
307 /**
308  * Multiply two size_t values checking for overflow.
309  * @return 0 if success, AVERROR(EINVAL) if overflow.
310  */
311 static inline int av_size_mult(size_t a, size_t b, size_t *r)
312 {
313  size_t t = a * b;
314  /* Hack inspired from glibc: only try the division if nelem and elsize
315  * are both greater than sqrt(SIZE_MAX). */
316  if ((a | b) >= ((size_t)1 << (sizeof(size_t) * 4)) && a && t / a != b)
317  return AVERROR(EINVAL);
318  *r = t;
319  return 0;
320 }
321 
322 /**
323  * Set the maximum size that may me allocated in one block.
324  */
325 void av_max_alloc(size_t max);
326 
327 /**
328  * deliberately overlapping memcpy implementation
329  * @param dst destination buffer
330  * @param back how many bytes back we start (the initial size of the overlapping window), must be > 0
331  * @param cnt number of bytes to copy, must be >= 0
332  *
333  * cnt > back is valid, this will copy the bytes we just copied,
334  * thus creating a repeating pattern with a period length of back.
335  */
336 void av_memcpy_backptr(uint8_t *dst, int back, int cnt);
337 
338 /**
339  * Reallocate the given block if it is not large enough, otherwise do nothing.
340  *
341  * @see av_realloc
342  */
343 void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);
344 
345 /**
346  * Allocate a buffer, reusing the given one if large enough.
347  *
348  * Contrary to av_fast_realloc the current buffer contents might not be
349  * preserved and on error the old buffer is freed, thus no special
350  * handling to avoid memleaks is necessary.
351  *
352  * @param ptr pointer to pointer to already allocated buffer, overwritten with pointer to new buffer
353  * @param size size of the buffer *ptr points to
354  * @param min_size minimum size of *ptr buffer after returning, *ptr will be NULL and
355  * *size 0 if an error occurred.
356  */
357 void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size);
358 
359 /**
360  * @}
361  */
362 
363 #endif /* AVUTIL_MEM_H */