1 2 /* pngmem.c - stub functions for memory allocation 3 * 4 * Last changed in libpng 1.6.26 [October 20, 2016] 5 * Copyright (c) 1998-2002,2004,2006-2014,2016 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 than 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 /* Some compilers complain that this is always true. However, it 81 * can be false when integer overflow happens. 82 */ 83 if (size > 0 && size <= PNG_SIZE_MAX 84 # ifdef PNG_MAX_MALLOC_64K 85 && size <= 65536U 86 # endif 87 ) 88 { 89 #ifdef PNG_USER_MEM_SUPPORTED 90 if (png_ptr != NULL && png_ptr->malloc_fn != NULL) 91 return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size); 92 93 else 94 #endif 95 return malloc((size_t)size); /* checked for truncation above */ 96 } 97 98 else 99 return NULL; 100 } 101 102 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\ 103 defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) 104 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7 105 * that arises because of the checks in png_realloc_array that are repeated in 106 * png_malloc_array. 107 */ 108 static png_voidp 109 png_malloc_array_checked(png_const_structrp png_ptr, int nelements, 110 size_t element_size) 111 { 112 png_alloc_size_t req = (png_alloc_size_t)nelements; /* known to be > 0 */ 113 114 if (req <= PNG_SIZE_MAX/element_size) 115 return png_malloc_base(png_ptr, req * element_size); 116 117 /* The failure case when the request is too large */ 118 return NULL; 119 } 120 121 PNG_FUNCTION(png_voidp /* PRIVATE */, 122 png_malloc_array,(png_const_structrp png_ptr, int nelements, 123 size_t element_size),PNG_ALLOCATED) 124 { 125 if (nelements <= 0 || element_size == 0) 126 png_error(png_ptr, "internal error: array alloc"); 127 128 return png_malloc_array_checked(png_ptr, nelements, element_size); 129 } 130 131 PNG_FUNCTION(png_voidp /* PRIVATE */, 132 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array, 133 int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED) 134 { 135 /* These are internal errors: */ 136 if (add_elements <= 0 || element_size == 0 || old_elements < 0 || 137 (old_array == NULL && old_elements > 0)) 138 png_error(png_ptr, "internal error: array realloc"); 139 140 /* Check for overflow on the elements count (so the caller does not have to 141 * check.) 142 */ 143 if (add_elements <= INT_MAX - old_elements) 144 { 145 png_voidp new_array = png_malloc_array_checked(png_ptr, 146 old_elements+add_elements, element_size); 147 148 if (new_array != NULL) 149 { 150 /* Because png_malloc_array worked the size calculations below cannot 151 * overflow. 152 */ 153 if (old_elements > 0) 154 memcpy(new_array, old_array, element_size*(unsigned)old_elements); 155 156 memset((char*)new_array + element_size*(unsigned)old_elements, 0, 157 element_size*(unsigned)add_elements); 158 159 return new_array; 160 } 161 } 162 163 return NULL; /* error */ 164 } 165 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */ 166 167 /* Various functions that have different error handling are derived from this. 168 * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate 169 * function png_malloc_default is also provided. 170 */ 171 PNG_FUNCTION(png_voidp,PNGAPI 172 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED) 173 { 174 png_voidp ret; 175 176 if (png_ptr == NULL) 177 return NULL; 178 179 ret = png_malloc_base(png_ptr, size); 180 181 if (ret == NULL) 182 png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */ 183 184 return ret; 185 } 186 187 #ifdef PNG_USER_MEM_SUPPORTED 188 PNG_FUNCTION(png_voidp,PNGAPI 189 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size), 190 PNG_ALLOCATED PNG_DEPRECATED) 191 { 192 png_voidp ret; 193 194 if (png_ptr == NULL) 195 return NULL; 196 197 /* Passing 'NULL' here bypasses the application provided memory handler. */ 198 ret = png_malloc_base(NULL/*use malloc*/, size); 199 200 if (ret == NULL) 201 png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */ 202 203 return ret; 204 } 205 #endif /* USER_MEM */ 206 207 /* This function was added at libpng version 1.2.3. The png_malloc_warn() 208 * function will issue a png_warning and return NULL instead of issuing a 209 * png_error, if it fails to allocate the requested memory. 210 */ 211 PNG_FUNCTION(png_voidp,PNGAPI 212 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size), 213 PNG_ALLOCATED) 214 { 215 if (png_ptr != NULL) 216 { 217 png_voidp ret = png_malloc_base(png_ptr, size); 218 219 if (ret != NULL) 220 return ret; 221 222 png_warning(png_ptr, "Out of memory"); 223 } 224 225 return NULL; 226 } 227 228 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return 229 * without taking any action. 230 */ 231 void PNGAPI 232 png_free(png_const_structrp png_ptr, png_voidp ptr) 233 { 234 if (png_ptr == NULL || ptr == NULL) 235 return; 236 237 #ifdef PNG_USER_MEM_SUPPORTED 238 if (png_ptr->free_fn != NULL) 239 png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr); 240 241 else 242 png_free_default(png_ptr, ptr); 243 } 244 245 PNG_FUNCTION(void,PNGAPI 246 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED) 247 { 248 if (png_ptr == NULL || ptr == NULL) 249 return; 250 #endif /* USER_MEM */ 251 252 free(ptr); 253 } 254 255 #ifdef PNG_USER_MEM_SUPPORTED 256 /* This function is called when the application wants to use another method 257 * of allocating and freeing memory. 258 */ 259 void PNGAPI 260 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr 261 malloc_fn, png_free_ptr free_fn) 262 { 263 if (png_ptr != NULL) 264 { 265 png_ptr->mem_ptr = mem_ptr; 266 png_ptr->malloc_fn = malloc_fn; 267 png_ptr->free_fn = free_fn; 268 } 269 } 270 271 /* This function returns a pointer to the mem_ptr associated with the user 272 * functions. The application should free any memory associated with this 273 * pointer before png_write_destroy and png_read_destroy are called. 274 */ 275 png_voidp PNGAPI 276 png_get_mem_ptr(png_const_structrp png_ptr) 277 { 278 if (png_ptr == NULL) 279 return NULL; 280 281 return png_ptr->mem_ptr; 282 } 283 #endif /* USER_MEM */ 284 #endif /* READ || WRITE */ 285
