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comparison lib/libpng/pngmem.c @ 2296:6e178010fc29

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libpng
author Ritor1
date Mon, 17 Mar 2014 01:21:55 +0600
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2295:6fd03869f65c 2296:6e178010fc29
1
2 /* pngmem.c - stub functions for memory allocation
3 *
4 * Last changed in libpng 1.6.8 [December 19, 2013]
5 * Copyright (c) 1998-2013 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 *
13 * This file provides a location for all memory allocation. Users who
14 * need special memory handling are expected to supply replacement
15 * functions for png_malloc() and png_free(), and to use
16 * png_create_read_struct_2() and png_create_write_struct_2() to
17 * identify the replacement functions.
18 */
19
20 #include "pngpriv.h"
21
22 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
23 /* Free a png_struct */
24 void /* PRIVATE */
25 png_destroy_png_struct(png_structrp png_ptr)
26 {
27 if (png_ptr != NULL)
28 {
29 /* png_free might call png_error and may certainly call
30 * png_get_mem_ptr, so fake a temporary png_struct to support this.
31 */
32 png_struct dummy_struct = *png_ptr;
33 memset(png_ptr, 0, (sizeof *png_ptr));
34 png_free(&dummy_struct, png_ptr);
35
36 # ifdef PNG_SETJMP_SUPPORTED
37 /* We may have a jmp_buf left to deallocate. */
38 png_free_jmpbuf(&dummy_struct);
39 # endif
40 }
41 }
42
43 /* Allocate memory. For reasonable files, size should never exceed
44 * 64K. However, zlib may allocate more then 64K if you don't tell
45 * it not to. See zconf.h and png.h for more information. zlib does
46 * need to allocate exactly 64K, so whatever you call here must
47 * have the ability to do that.
48 */
49 PNG_FUNCTION(png_voidp,PNGAPI
50 png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
51 {
52 png_voidp ret;
53
54 ret = png_malloc(png_ptr, size);
55
56 if (ret != NULL)
57 memset(ret, 0, size);
58
59 return ret;
60 }
61
62 /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
63 * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
64 * Checking and error handling must happen outside this routine; it returns NULL
65 * if the allocation cannot be done (for any reason.)
66 */
67 PNG_FUNCTION(png_voidp /* PRIVATE */,
68 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
69 PNG_ALLOCATED)
70 {
71 /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
72 * allocators have also been removed in 1.6.0, so any 16-bit system now has
73 * to implement a user memory handler. This checks to be sure it isn't
74 * called with big numbers.
75 */
76 #ifndef PNG_USER_MEM_SUPPORTED
77 PNG_UNUSED(png_ptr)
78 #endif
79
80 if (size > 0 && size <= PNG_SIZE_MAX
81 # ifdef PNG_MAX_MALLOC_64K
82 && size <= 65536U
83 # endif
84 )
85 {
86 #ifdef PNG_USER_MEM_SUPPORTED
87 if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
88 return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
89
90 else
91 #endif
92 return malloc((size_t)size); /* checked for truncation above */
93 }
94
95 else
96 return NULL;
97 }
98
99 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
100 defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
101 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
102 * that arises because of the checks in png_realloc_array that are repeated in
103 * png_malloc_array.
104 */
105 static png_voidp
106 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
107 size_t element_size)
108 {
109 png_alloc_size_t req = nelements; /* known to be > 0 */
110
111 if (req <= PNG_SIZE_MAX/element_size)
112 return png_malloc_base(png_ptr, req * element_size);
113
114 /* The failure case when the request is too large */
115 return NULL;
116 }
117
118 PNG_FUNCTION(png_voidp /* PRIVATE */,
119 png_malloc_array,(png_const_structrp png_ptr, int nelements,
120 size_t element_size),PNG_ALLOCATED)
121 {
122 if (nelements <= 0 || element_size == 0)
123 png_error(png_ptr, "internal error: array alloc");
124
125 return png_malloc_array_checked(png_ptr, nelements, element_size);
126 }
127
128 PNG_FUNCTION(png_voidp /* PRIVATE */,
129 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
130 int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
131 {
132 /* These are internal errors: */
133 if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
134 (old_array == NULL && old_elements > 0))
135 png_error(png_ptr, "internal error: array realloc");
136
137 /* Check for overflow on the elements count (so the caller does not have to
138 * check.)
139 */
140 if (add_elements <= INT_MAX - old_elements)
141 {
142 png_voidp new_array = png_malloc_array_checked(png_ptr,
143 old_elements+add_elements, element_size);
144
145 if (new_array != NULL)
146 {
147 /* Because png_malloc_array worked the size calculations below cannot
148 * overflow.
149 */
150 if (old_elements > 0)
151 memcpy(new_array, old_array, element_size*(unsigned)old_elements);
152
153 memset((char*)new_array + element_size*(unsigned)old_elements, 0,
154 element_size*(unsigned)add_elements);
155
156 return new_array;
157 }
158 }
159
160 return NULL; /* error */
161 }
162 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
163
164 /* Various functions that have different error handling are derived from this.
165 * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
166 * function png_malloc_default is also provided.
167 */
168 PNG_FUNCTION(png_voidp,PNGAPI
169 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
170 {
171 png_voidp ret;
172
173 if (png_ptr == NULL)
174 return NULL;
175
176 ret = png_malloc_base(png_ptr, size);
177
178 if (ret == NULL)
179 png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
180
181 return ret;
182 }
183
184 #ifdef PNG_USER_MEM_SUPPORTED
185 PNG_FUNCTION(png_voidp,PNGAPI
186 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
187 PNG_ALLOCATED PNG_DEPRECATED)
188 {
189 png_voidp ret;
190
191 if (png_ptr == NULL)
192 return NULL;
193
194 /* Passing 'NULL' here bypasses the application provided memory handler. */
195 ret = png_malloc_base(NULL/*use malloc*/, size);
196
197 if (ret == NULL)
198 png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
199
200 return ret;
201 }
202 #endif /* PNG_USER_MEM_SUPPORTED */
203
204 /* This function was added at libpng version 1.2.3. The png_malloc_warn()
205 * function will issue a png_warning and return NULL instead of issuing a
206 * png_error, if it fails to allocate the requested memory.
207 */
208 PNG_FUNCTION(png_voidp,PNGAPI
209 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
210 PNG_ALLOCATED)
211 {
212 if (png_ptr != NULL)
213 {
214 png_voidp ret = png_malloc_base(png_ptr, size);
215
216 if (ret != NULL)
217 return ret;
218
219 png_warning(png_ptr, "Out of memory");
220 }
221
222 return NULL;
223 }
224
225 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return
226 * without taking any action.
227 */
228 void PNGAPI
229 png_free(png_const_structrp png_ptr, png_voidp ptr)
230 {
231 if (png_ptr == NULL || ptr == NULL)
232 return;
233
234 #ifdef PNG_USER_MEM_SUPPORTED
235 if (png_ptr->free_fn != NULL)
236 png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
237
238 else
239 png_free_default(png_ptr, ptr);
240 }
241
242 PNG_FUNCTION(void,PNGAPI
243 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
244 {
245 if (png_ptr == NULL || ptr == NULL)
246 return;
247 #endif /* PNG_USER_MEM_SUPPORTED */
248
249 free(ptr);
250 }
251
252 #ifdef PNG_USER_MEM_SUPPORTED
253 /* This function is called when the application wants to use another method
254 * of allocating and freeing memory.
255 */
256 void PNGAPI
257 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
258 malloc_fn, png_free_ptr free_fn)
259 {
260 if (png_ptr != NULL)
261 {
262 png_ptr->mem_ptr = mem_ptr;
263 png_ptr->malloc_fn = malloc_fn;
264 png_ptr->free_fn = free_fn;
265 }
266 }
267
268 /* This function returns a pointer to the mem_ptr associated with the user
269 * functions. The application should free any memory associated with this
270 * pointer before png_write_destroy and png_read_destroy are called.
271 */
272 png_voidp PNGAPI
273 png_get_mem_ptr(png_const_structrp png_ptr)
274 {
275 if (png_ptr == NULL)
276 return NULL;
277
278 return png_ptr->mem_ptr;
279 }
280 #endif /* PNG_USER_MEM_SUPPORTED */
281 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */