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1 | |
2 /* pngmem.c - stub functions for memory allocation | |
3 * | |
4 * Last changed in libpng 1.6.15 [November 20, 2014] | |
5 * Copyright (c) 1998-2014 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 void* FXMEM_DefaultAlloc(int byte_size, int); | |
23 void FXMEM_DefaultFree(void* pointer, int); | |
24 | |
25 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) | |
26 /* Free a png_struct */ | |
27 void /* PRIVATE */ | |
28 png_destroy_png_struct(png_structrp png_ptr) | |
29 { | |
30 if (png_ptr != NULL) | |
31 { | |
32 /* png_free might call png_error and may certainly call | |
33 * png_get_mem_ptr, so fake a temporary png_struct to support this. | |
34 */ | |
35 png_struct dummy_struct = *png_ptr; | |
36 memset(png_ptr, 0, (sizeof *png_ptr)); | |
37 png_free(&dummy_struct, png_ptr); | |
38 | |
39 # ifdef PNG_SETJMP_SUPPORTED | |
40 /* We may have a jmp_buf left to deallocate. */ | |
41 png_free_jmpbuf(&dummy_struct); | |
42 # endif | |
43 } | |
44 } | |
45 | |
46 /* Allocate memory. For reasonable files, size should never exceed | |
47 * 64K. However, zlib may allocate more than 64K if you don't tell | |
48 * it not to. See zconf.h and png.h for more information. zlib does | |
49 * need to allocate exactly 64K, so whatever you call here must | |
50 * have the ability to do that. | |
51 */ | |
52 PNG_FUNCTION(png_voidp,PNGAPI | |
53 png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED) | |
54 { | |
55 png_voidp ret; | |
56 | |
57 ret = png_malloc(png_ptr, size); | |
58 | |
59 if (ret != NULL) | |
60 memset(ret, 0, size); | |
61 | |
62 return ret; | |
63 } | |
64 | |
65 /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of | |
66 * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED. | |
67 * Checking and error handling must happen outside this routine; it returns NULL | |
68 * if the allocation cannot be done (for any reason.) | |
69 */ | |
70 PNG_FUNCTION(png_voidp /* PRIVATE */, | |
71 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size), | |
72 PNG_ALLOCATED) | |
73 { | |
74 /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS | |
75 * allocators have also been removed in 1.6.0, so any 16-bit system now has | |
76 * to implement a user memory handler. This checks to be sure it isn't | |
77 * called with big numbers. | |
78 */ | |
79 #ifndef PNG_USER_MEM_SUPPORTED | |
80 PNG_UNUSED(png_ptr) | |
81 #endif | |
82 | |
83 /* Some compilers complain that this is always true. However, it | |
84 * can be false when integer overflow happens. | |
85 */ | |
86 if (size > 0 && size <= PNG_SIZE_MAX | |
87 # ifdef PNG_MAX_MALLOC_64K | |
88 && size <= 65536U | |
89 # endif | |
90 ) | |
91 { | |
92 #ifdef PNG_USER_MEM_SUPPORTED | |
93 if (png_ptr != NULL && png_ptr->malloc_fn != NULL) | |
94 return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size); | |
95 | |
96 else | |
97 #endif | |
98 return FXMEM_DefaultAlloc((int)size, 0); | |
99 } | |
100 | |
101 else | |
102 return NULL; | |
103 } | |
104 | |
105 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\ | |
106 defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) | |
107 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7 | |
108 * that arises because of the checks in png_realloc_array that are repeated in | |
109 * png_malloc_array. | |
110 */ | |
111 static png_voidp | |
112 png_malloc_array_checked(png_const_structrp png_ptr, int nelements, | |
113 size_t element_size) | |
114 { | |
115 png_alloc_size_t req = nelements; /* known to be > 0 */ | |
116 | |
117 if (req <= PNG_SIZE_MAX/element_size) | |
118 return png_malloc_base(png_ptr, req * element_size); | |
119 | |
120 /* The failure case when the request is too large */ | |
121 return NULL; | |
122 } | |
123 | |
124 PNG_FUNCTION(png_voidp /* PRIVATE */, | |
125 png_malloc_array,(png_const_structrp png_ptr, int nelements, | |
126 size_t element_size),PNG_ALLOCATED) | |
127 { | |
128 if (nelements <= 0 || element_size == 0) | |
129 png_error(png_ptr, "internal error: array alloc"); | |
130 | |
131 return png_malloc_array_checked(png_ptr, nelements, element_size); | |
132 } | |
133 | |
134 PNG_FUNCTION(png_voidp /* PRIVATE */, | |
135 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array, | |
136 int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED) | |
137 { | |
138 /* These are internal errors: */ | |
139 if (add_elements <= 0 || element_size == 0 || old_elements < 0 || | |
140 (old_array == NULL && old_elements > 0)) | |
141 png_error(png_ptr, "internal error: array realloc"); | |
142 | |
143 /* Check for overflow on the elements count (so the caller does not have to | |
144 * check.) | |
145 */ | |
146 if (add_elements <= INT_MAX - old_elements) | |
147 { | |
148 png_voidp new_array = png_malloc_array_checked(png_ptr, | |
149 old_elements+add_elements, element_size); | |
150 | |
151 if (new_array != NULL) | |
152 { | |
153 /* Because png_malloc_array worked the size calculations below cannot | |
154 * overflow. | |
155 */ | |
156 if (old_elements > 0) | |
157 memcpy(new_array, old_array, element_size*(unsigned)old_elements); | |
158 | |
159 memset((char*)new_array + element_size*(unsigned)old_elements, 0, | |
160 element_size*(unsigned)add_elements); | |
161 | |
162 return new_array; | |
163 } | |
164 } | |
165 | |
166 return NULL; /* error */ | |
167 } | |
168 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */ | |
169 | |
170 /* Various functions that have different error handling are derived from this. | |
171 * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate | |
172 * function png_malloc_default is also provided. | |
173 */ | |
174 PNG_FUNCTION(png_voidp,PNGAPI | |
175 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED) | |
176 { | |
177 png_voidp ret; | |
178 | |
179 if (png_ptr == NULL) | |
180 return NULL; | |
181 | |
182 ret = png_malloc_base(png_ptr, size); | |
183 | |
184 if (ret == NULL) | |
185 png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */ | |
186 | |
187 return ret; | |
188 } | |
189 | |
190 #ifdef PNG_USER_MEM_SUPPORTED | |
191 PNG_FUNCTION(png_voidp,PNGAPI | |
192 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size), | |
193 PNG_ALLOCATED PNG_DEPRECATED) | |
194 { | |
195 png_voidp ret; | |
196 | |
197 if (png_ptr == NULL) | |
198 return NULL; | |
199 | |
200 /* Passing 'NULL' here bypasses the application provided memory handler. */ | |
201 ret = png_malloc_base(NULL/*use malloc*/, size); | |
202 | |
203 if (ret == NULL) | |
204 png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */ | |
205 | |
206 return ret; | |
207 } | |
208 #endif /* USER_MEM */ | |
209 | |
210 /* This function was added at libpng version 1.2.3. The png_malloc_warn() | |
211 * function will issue a png_warning and return NULL instead of issuing a | |
212 * png_error, if it fails to allocate the requested memory. | |
213 */ | |
214 PNG_FUNCTION(png_voidp,PNGAPI | |
215 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size), | |
216 PNG_ALLOCATED) | |
217 { | |
218 if (png_ptr != NULL) | |
219 { | |
220 png_voidp ret = png_malloc_base(png_ptr, size); | |
221 | |
222 if (ret != NULL) | |
223 return ret; | |
224 | |
225 png_warning(png_ptr, "Out of memory"); | |
226 } | |
227 | |
228 return NULL; | |
229 } | |
230 | |
231 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return | |
232 * without taking any action. | |
233 */ | |
234 void PNGAPI | |
235 png_free(png_const_structrp png_ptr, png_voidp ptr) | |
236 { | |
237 if (png_ptr == NULL || ptr == NULL) | |
238 return; | |
239 | |
240 #ifdef PNG_USER_MEM_SUPPORTED | |
241 if (png_ptr->free_fn != NULL) | |
242 png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr); | |
243 | |
244 else | |
245 png_free_default(png_ptr, ptr); | |
246 } | |
247 | |
248 PNG_FUNCTION(void,PNGAPI | |
249 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED) | |
250 { | |
251 if (png_ptr == NULL || ptr == NULL) | |
252 return; | |
253 #endif /* USER_MEM */ | |
254 | |
255 FXMEM_DefaultFree(ptr, 0); | |
256 } | |
257 | |
258 #ifdef PNG_USER_MEM_SUPPORTED | |
259 /* This function is called when the application wants to use another method | |
260 * of allocating and freeing memory. | |
261 */ | |
262 void PNGAPI | |
263 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr | |
264 malloc_fn, png_free_ptr free_fn) | |
265 { | |
266 if (png_ptr != NULL) | |
267 { | |
268 png_ptr->mem_ptr = mem_ptr; | |
269 png_ptr->malloc_fn = malloc_fn; | |
270 png_ptr->free_fn = free_fn; | |
271 } | |
272 } | |
273 | |
274 /* This function returns a pointer to the mem_ptr associated with the user | |
275 * functions. The application should free any memory associated with this | |
276 * pointer before png_write_destroy and png_read_destroy are called. | |
277 */ | |
278 png_voidp PNGAPI | |
279 png_get_mem_ptr(png_const_structrp png_ptr) | |
280 { | |
281 if (png_ptr == NULL) | |
282 return NULL; | |
283 | |
284 return png_ptr->mem_ptr; | |
285 } | |
286 #endif /* USER_MEM */ | |
287 #endif /* READ || WRITE */ | |
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