[96425] | 1 |
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| 2 | /* pngmem.c - stub functions for memory allocation
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| 3 | *
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| 4 | * Copyright (c) 2018 Cosmin Truta
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| 5 | * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
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| 6 | * Copyright (c) 1996-1997 Andreas Dilger
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| 7 | * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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| 8 | *
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| 9 | * This code is released under the libpng license.
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| 10 | * For conditions of distribution and use, see the disclaimer
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| 11 | * and license in png.h
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| 12 | *
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| 13 | * This file provides a location for all memory allocation. Users who
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| 14 | * need special memory handling are expected to supply replacement
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| 15 | * functions for png_malloc() and png_free(), and to use
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| 16 | * png_create_read_struct_2() and png_create_write_struct_2() to
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| 17 | * identify the replacement functions.
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| 18 | */
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| 19 |
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| 20 | #include "pngpriv.h"
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| 21 |
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| 22 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
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| 23 | /* Free a png_struct */
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| 24 | void /* PRIVATE */
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| 25 | png_destroy_png_struct(png_structrp png_ptr)
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| 26 | {
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| 27 | if (png_ptr != NULL)
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| 28 | {
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| 29 | /* png_free might call png_error and may certainly call
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| 30 | * png_get_mem_ptr, so fake a temporary png_struct to support this.
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| 31 | */
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| 32 | png_struct dummy_struct = *png_ptr;
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| 33 | memset(png_ptr, 0, (sizeof *png_ptr));
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| 34 | png_free(&dummy_struct, png_ptr);
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| 35 |
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| 36 | # ifdef PNG_SETJMP_SUPPORTED
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| 37 | /* We may have a jmp_buf left to deallocate. */
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| 38 | png_free_jmpbuf(&dummy_struct);
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| 39 | # endif
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| 40 | }
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| 41 | }
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| 42 |
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| 43 | /* Allocate memory. For reasonable files, size should never exceed
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| 44 | * 64K. However, zlib may allocate more than 64K if you don't tell
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| 45 | * it not to. See zconf.h and png.h for more information. zlib does
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| 46 | * need to allocate exactly 64K, so whatever you call here must
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| 47 | * have the ability to do that.
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| 48 | */
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| 49 | PNG_FUNCTION(png_voidp,PNGAPI
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| 50 | png_calloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
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| 51 | {
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| 52 | png_voidp ret;
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| 53 |
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| 54 | ret = png_malloc(png_ptr, size);
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| 55 |
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| 56 | if (ret != NULL)
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| 57 | memset(ret, 0, size);
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| 58 |
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| 59 | return ret;
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| 60 | }
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| 61 |
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| 62 | /* png_malloc_base, an internal function added at libpng 1.6.0, does the work of
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| 63 | * allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
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| 64 | * Checking and error handling must happen outside this routine; it returns NULL
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| 65 | * if the allocation cannot be done (for any reason.)
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| 66 | */
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| 67 | PNG_FUNCTION(png_voidp /* PRIVATE */,
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| 68 | png_malloc_base,(png_const_structrp png_ptr, png_alloc_size_t size),
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| 69 | PNG_ALLOCATED)
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| 70 | {
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| 71 | /* Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
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| 72 | * allocators have also been removed in 1.6.0, so any 16-bit system now has
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| 73 | * to implement a user memory handler. This checks to be sure it isn't
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| 74 | * called with big numbers.
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| 75 | */
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| 76 | #ifndef PNG_USER_MEM_SUPPORTED
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| 77 | PNG_UNUSED(png_ptr)
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| 78 | #endif
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| 79 |
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| 80 | /* Some compilers complain that this is always true. However, it
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| 81 | * can be false when integer overflow happens.
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| 82 | */
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| 83 | if (size > 0 && size <= PNG_SIZE_MAX
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| 84 | # ifdef PNG_MAX_MALLOC_64K
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| 85 | && size <= 65536U
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| 86 | # endif
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| 87 | )
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| 88 | {
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| 89 | #ifdef PNG_USER_MEM_SUPPORTED
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| 90 | if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
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| 91 | return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
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| 92 |
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| 93 | else
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| 94 | #endif
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| 95 | return malloc((size_t)size); /* checked for truncation above */
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| 96 | }
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| 97 |
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| 98 | else
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| 99 | return NULL;
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| 100 | }
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| 101 |
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| 102 | #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
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| 103 | defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
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| 104 | /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
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| 105 | * that arises because of the checks in png_realloc_array that are repeated in
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| 106 | * png_malloc_array.
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| 107 | */
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| 108 | static png_voidp
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| 109 | png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
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| 110 | size_t element_size)
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| 111 | {
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| 112 | png_alloc_size_t req = (png_alloc_size_t)nelements; /* known to be > 0 */
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| 113 |
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| 114 | if (req <= PNG_SIZE_MAX/element_size)
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| 115 | return png_malloc_base(png_ptr, req * element_size);
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| 116 |
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| 117 | /* The failure case when the request is too large */
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| 118 | return NULL;
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| 119 | }
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| 120 |
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| 121 | PNG_FUNCTION(png_voidp /* PRIVATE */,
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| 122 | png_malloc_array,(png_const_structrp png_ptr, int nelements,
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| 123 | size_t element_size),PNG_ALLOCATED)
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| 124 | {
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| 125 | if (nelements <= 0 || element_size == 0)
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| 126 | png_error(png_ptr, "internal error: array alloc");
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| 127 |
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| 128 | return png_malloc_array_checked(png_ptr, nelements, element_size);
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| 129 | }
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| 130 |
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| 131 | PNG_FUNCTION(png_voidp /* PRIVATE */,
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| 132 | png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
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| 133 | int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
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| 134 | {
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| 135 | /* These are internal errors: */
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| 136 | if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
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| 137 | (old_array == NULL && old_elements > 0))
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| 138 | png_error(png_ptr, "internal error: array realloc");
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| 139 |
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| 140 | /* Check for overflow on the elements count (so the caller does not have to
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| 141 | * check.)
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| 142 | */
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| 143 | if (add_elements <= INT_MAX - old_elements)
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| 144 | {
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| 145 | png_voidp new_array = png_malloc_array_checked(png_ptr,
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| 146 | old_elements+add_elements, element_size);
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| 147 |
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| 148 | if (new_array != NULL)
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| 149 | {
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| 150 | /* Because png_malloc_array worked the size calculations below cannot
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| 151 | * overflow.
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| 152 | */
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| 153 | if (old_elements > 0)
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| 154 | memcpy(new_array, old_array, element_size*(unsigned)old_elements);
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| 155 |
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| 156 | memset((char*)new_array + element_size*(unsigned)old_elements, 0,
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| 157 | element_size*(unsigned)add_elements);
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| 158 |
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| 159 | return new_array;
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| 160 | }
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| 161 | }
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| 162 |
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| 163 | return NULL; /* error */
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| 164 | }
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| 165 | #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
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| 166 |
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| 167 | /* Various functions that have different error handling are derived from this.
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| 168 | * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
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| 169 | * function png_malloc_default is also provided.
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| 170 | */
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| 171 | PNG_FUNCTION(png_voidp,PNGAPI
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| 172 | png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
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| 173 | {
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| 174 | png_voidp ret;
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| 175 |
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| 176 | if (png_ptr == NULL)
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| 177 | return NULL;
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| 178 |
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| 179 | ret = png_malloc_base(png_ptr, size);
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| 180 |
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| 181 | if (ret == NULL)
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| 182 | png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
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| 183 |
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| 184 | return ret;
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| 185 | }
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| 186 |
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| 187 | #ifdef PNG_USER_MEM_SUPPORTED
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| 188 | PNG_FUNCTION(png_voidp,PNGAPI
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| 189 | png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
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| 190 | PNG_ALLOCATED PNG_DEPRECATED)
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| 191 | {
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| 192 | png_voidp ret;
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| 193 |
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| 194 | if (png_ptr == NULL)
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| 195 | return NULL;
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| 196 |
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| 197 | /* Passing 'NULL' here bypasses the application provided memory handler. */
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| 198 | ret = png_malloc_base(NULL/*use malloc*/, size);
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| 199 |
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| 200 | if (ret == NULL)
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| 201 | png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
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| 202 |
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| 203 | return ret;
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| 204 | }
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| 205 | #endif /* USER_MEM */
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| 206 |
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| 207 | /* This function was added at libpng version 1.2.3. The png_malloc_warn()
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| 208 | * function will issue a png_warning and return NULL instead of issuing a
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| 209 | * png_error, if it fails to allocate the requested memory.
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| 210 | */
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| 211 | PNG_FUNCTION(png_voidp,PNGAPI
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| 212 | png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
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| 213 | PNG_ALLOCATED)
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| 214 | {
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| 215 | if (png_ptr != NULL)
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| 216 | {
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| 217 | png_voidp ret = png_malloc_base(png_ptr, size);
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| 218 |
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| 219 | if (ret != NULL)
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| 220 | return ret;
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| 221 |
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| 222 | png_warning(png_ptr, "Out of memory");
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| 223 | }
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| 224 |
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| 225 | return NULL;
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| 226 | }
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| 227 |
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| 228 | /* Free a pointer allocated by png_malloc(). If ptr is NULL, return
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| 229 | * without taking any action.
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| 230 | */
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| 231 | void PNGAPI
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| 232 | png_free(png_const_structrp png_ptr, png_voidp ptr)
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| 233 | {
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| 234 | if (png_ptr == NULL || ptr == NULL)
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| 235 | return;
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| 236 |
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| 237 | #ifdef PNG_USER_MEM_SUPPORTED
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| 238 | if (png_ptr->free_fn != NULL)
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| 239 | png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
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| 240 |
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| 241 | else
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| 242 | png_free_default(png_ptr, ptr);
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| 243 | }
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| 244 |
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| 245 | PNG_FUNCTION(void,PNGAPI
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| 246 | png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
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| 247 | {
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| 248 | if (png_ptr == NULL || ptr == NULL)
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| 249 | return;
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| 250 | #endif /* USER_MEM */
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| 251 |
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| 252 | free(ptr);
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| 253 | }
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| 254 |
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| 255 | #ifdef PNG_USER_MEM_SUPPORTED
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| 256 | /* This function is called when the application wants to use another method
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| 257 | * of allocating and freeing memory.
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| 258 | */
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| 259 | void PNGAPI
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| 260 | png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
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| 261 | malloc_fn, png_free_ptr free_fn)
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| 262 | {
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| 263 | if (png_ptr != NULL)
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| 264 | {
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| 265 | png_ptr->mem_ptr = mem_ptr;
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| 266 | png_ptr->malloc_fn = malloc_fn;
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| 267 | png_ptr->free_fn = free_fn;
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| 268 | }
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| 269 | }
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| 270 |
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| 271 | /* This function returns a pointer to the mem_ptr associated with the user
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| 272 | * functions. The application should free any memory associated with this
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| 273 | * pointer before png_write_destroy and png_read_destroy are called.
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| 274 | */
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| 275 | png_voidp PNGAPI
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| 276 | png_get_mem_ptr(png_const_structrp png_ptr)
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| 277 | {
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| 278 | if (png_ptr == NULL)
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| 279 | return NULL;
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| 280 |
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| 281 | return png_ptr->mem_ptr;
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| 282 | }
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| 283 | #endif /* USER_MEM */
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| 284 | #endif /* READ || WRITE */
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