2 /* pngmem.c - stub functions for memory allocation
4 * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
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.)
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
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.
22 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
23 /* Free a png_struct */
25 png_destroy_png_struct(png_structrp png_ptr)
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.
32 png_struct dummy_struct = *png_ptr;
33 memset(png_ptr, 0, (sizeof *png_ptr));
34 png_free(&dummy_struct, png_ptr);
36 # ifdef PNG_SETJMP_SUPPORTED
37 /* We may have a jmp_buf left to deallocate. */
38 png_free_jmpbuf(&dummy_struct);
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.
49 PNG_FUNCTION(png_voidp,PNGAPI
50 png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
54 ret = png_malloc(png_ptr, size);
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.)
67 PNG_FUNCTION(png_voidp /* PRIVATE */,
68 png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
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.
76 #ifndef PNG_USER_MEM_SUPPORTED
80 if (size > 0 && size <= PNG_SIZE_MAX
81 # ifdef PNG_MAX_MALLOC_64K
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);
92 return malloc((size_t)size); /* checked for truncation above */
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
106 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
109 png_alloc_size_t req = nelements; /* known to be > 0 */
111 if (req <= PNG_SIZE_MAX/element_size)
112 return png_malloc_base(png_ptr, req * element_size);
114 /* The failure case when the request is too large */
118 PNG_FUNCTION(png_voidp /* PRIVATE */,
119 png_malloc_array,(png_const_structrp png_ptr, int nelements,
120 size_t element_size),PNG_ALLOCATED)
122 if (nelements <= 0 || element_size == 0)
123 png_error(png_ptr, "internal error: array alloc");
125 return png_malloc_array_checked(png_ptr, nelements, element_size);
128 PNG_FUNCTION(png_voidp /* PRIVATE */,
129 png_realloc_array,(png_structrp png_ptr, png_const_voidp old_array,
130 int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
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");
137 /* Check for overflow on the elements count (so the caller does not have to
140 if (add_elements <= INT_MAX - old_elements)
142 png_voidp new_array = png_malloc_array_checked(png_ptr,
143 old_elements+add_elements, element_size);
145 if (new_array != NULL)
147 /* Because png_malloc_array worked the size calculations below cannot
150 if (old_elements > 0)
151 memcpy(new_array, old_array, element_size*(unsigned)old_elements);
153 memset((char*)new_array + element_size*(unsigned)old_elements, 0,
154 element_size*(unsigned)add_elements);
160 #ifdef PNG_READ_SUPPORTED
161 # ifdef PNG_USER_LIMITS_SUPPORTED
162 /* The potential overflow case. Set the cache counter so libpng will
163 * not make any more attempts
165 png_ptr->user_chunk_cache_max = 2;
169 return NULL; /* error */
171 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
173 /* Various functions that have different error handling are derived from this.
174 * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
175 * function png_malloc_default is also provided.
177 PNG_FUNCTION(png_voidp,PNGAPI
178 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
185 ret = png_malloc_base(png_ptr, size);
188 png_error(png_ptr, "Out of memory");
193 /* This function was added at libpng version 1.2.3. The png_malloc_warn()
194 * function will issue a png_warning and return NULL instead of issuing a
195 * png_error, if it fails to allocate the requested memory.
197 PNG_FUNCTION(png_voidp,PNGAPI
198 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
203 png_voidp ret = png_malloc_base(png_ptr, size);
208 png_warning(png_ptr, "Out of memory");
214 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return
215 * without taking any action.
218 png_free(png_const_structrp png_ptr, png_voidp ptr)
220 if (png_ptr == NULL || ptr == NULL)
223 #ifdef PNG_USER_MEM_SUPPORTED
224 if (png_ptr->free_fn != NULL)
225 png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
228 #endif /* PNG_USER_MEM_SUPPORTED */
232 #ifdef PNG_USER_MEM_SUPPORTED
233 /* This function is called when the application wants to use another method
234 * of allocating and freeing memory.
237 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
238 malloc_fn, png_free_ptr free_fn)
242 png_ptr->mem_ptr = mem_ptr;
243 png_ptr->malloc_fn = malloc_fn;
244 png_ptr->free_fn = free_fn;
248 /* This function returns a pointer to the mem_ptr associated with the user
249 * functions. The application should free any memory associated with this
250 * pointer before png_write_destroy and png_read_destroy are called.
253 png_get_mem_ptr(png_const_structrp png_ptr)
258 return png_ptr->mem_ptr;
260 #endif /* PNG_USER_MEM_SUPPORTED */
261 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */