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2296
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1
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2 /* pngmem.c - stub functions for memory allocation
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3 *
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4 * Last changed in libpng 1.6.8 [December 19, 2013]
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5 * Copyright (c) 1998-2013 Glenn Randers-Pehrson
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6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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7 * (Version 0.88 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 then 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 if (size > 0 && size <= PNG_SIZE_MAX
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81 # ifdef PNG_MAX_MALLOC_64K
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82 && size <= 65536U
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83 # endif
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84 )
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85 {
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86 #ifdef PNG_USER_MEM_SUPPORTED
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87 if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
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88 return png_ptr->malloc_fn(png_constcast(png_structrp,png_ptr), size);
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89
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90 else
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91 #endif
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92 return malloc((size_t)size); /* checked for truncation above */
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93 }
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94
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95 else
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96 return NULL;
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97 }
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98
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99 #if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
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100 defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED)
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101 /* This is really here only to work round a spurious warning in GCC 4.6 and 4.7
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102 * that arises because of the checks in png_realloc_array that are repeated in
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103 * png_malloc_array.
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104 */
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105 static png_voidp
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106 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
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107 size_t element_size)
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108 {
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109 png_alloc_size_t req = nelements; /* known to be > 0 */
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110
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111 if (req <= PNG_SIZE_MAX/element_size)
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112 return png_malloc_base(png_ptr, req * element_size);
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113
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114 /* The failure case when the request is too large */
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115 return NULL;
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116 }
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117
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118 PNG_FUNCTION(png_voidp /* PRIVATE */,
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119 png_malloc_array,(png_const_structrp png_ptr, int nelements,
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120 size_t element_size),PNG_ALLOCATED)
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121 {
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122 if (nelements <= 0 || element_size == 0)
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123 png_error(png_ptr, "internal error: array alloc");
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124
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125 return png_malloc_array_checked(png_ptr, nelements, element_size);
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126 }
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127
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128 PNG_FUNCTION(png_voidp /* PRIVATE */,
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129 png_realloc_array,(png_const_structrp png_ptr, png_const_voidp old_array,
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130 int old_elements, int add_elements, size_t element_size),PNG_ALLOCATED)
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131 {
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132 /* These are internal errors: */
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133 if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
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134 (old_array == NULL && old_elements > 0))
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135 png_error(png_ptr, "internal error: array realloc");
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136
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137 /* Check for overflow on the elements count (so the caller does not have to
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138 * check.)
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139 */
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140 if (add_elements <= INT_MAX - old_elements)
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141 {
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142 png_voidp new_array = png_malloc_array_checked(png_ptr,
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143 old_elements+add_elements, element_size);
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144
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145 if (new_array != NULL)
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146 {
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147 /* Because png_malloc_array worked the size calculations below cannot
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148 * overflow.
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149 */
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150 if (old_elements > 0)
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151 memcpy(new_array, old_array, element_size*(unsigned)old_elements);
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152
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153 memset((char*)new_array + element_size*(unsigned)old_elements, 0,
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154 element_size*(unsigned)add_elements);
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155
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156 return new_array;
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157 }
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158 }
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159
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160 return NULL; /* error */
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161 }
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162 #endif /* TEXT || sPLT || STORE_UNKNOWN_CHUNKS */
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163
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164 /* Various functions that have different error handling are derived from this.
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165 * png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
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166 * function png_malloc_default is also provided.
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167 */
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168 PNG_FUNCTION(png_voidp,PNGAPI
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169 png_malloc,(png_const_structrp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
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170 {
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171 png_voidp ret;
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172
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173 if (png_ptr == NULL)
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174 return NULL;
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175
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176 ret = png_malloc_base(png_ptr, size);
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177
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178 if (ret == NULL)
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179 png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
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180
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181 return ret;
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182 }
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183
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184 #ifdef PNG_USER_MEM_SUPPORTED
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185 PNG_FUNCTION(png_voidp,PNGAPI
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186 png_malloc_default,(png_const_structrp png_ptr, png_alloc_size_t size),
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187 PNG_ALLOCATED PNG_DEPRECATED)
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188 {
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189 png_voidp ret;
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190
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191 if (png_ptr == NULL)
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192 return NULL;
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193
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194 /* Passing 'NULL' here bypasses the application provided memory handler. */
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195 ret = png_malloc_base(NULL/*use malloc*/, size);
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196
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197 if (ret == NULL)
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198 png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
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199
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200 return ret;
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201 }
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202 #endif /* PNG_USER_MEM_SUPPORTED */
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203
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204 /* This function was added at libpng version 1.2.3. The png_malloc_warn()
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205 * function will issue a png_warning and return NULL instead of issuing a
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206 * png_error, if it fails to allocate the requested memory.
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207 */
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208 PNG_FUNCTION(png_voidp,PNGAPI
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209 png_malloc_warn,(png_const_structrp png_ptr, png_alloc_size_t size),
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210 PNG_ALLOCATED)
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211 {
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212 if (png_ptr != NULL)
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213 {
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214 png_voidp ret = png_malloc_base(png_ptr, size);
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215
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216 if (ret != NULL)
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217 return ret;
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218
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219 png_warning(png_ptr, "Out of memory");
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220 }
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221
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222 return NULL;
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223 }
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224
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225 /* Free a pointer allocated by png_malloc(). If ptr is NULL, return
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226 * without taking any action.
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227 */
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228 void PNGAPI
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229 png_free(png_const_structrp png_ptr, png_voidp ptr)
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230 {
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231 if (png_ptr == NULL || ptr == NULL)
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232 return;
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233
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234 #ifdef PNG_USER_MEM_SUPPORTED
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235 if (png_ptr->free_fn != NULL)
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236 png_ptr->free_fn(png_constcast(png_structrp,png_ptr), ptr);
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237
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238 else
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239 png_free_default(png_ptr, ptr);
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240 }
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241
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242 PNG_FUNCTION(void,PNGAPI
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243 png_free_default,(png_const_structrp png_ptr, png_voidp ptr),PNG_DEPRECATED)
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244 {
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245 if (png_ptr == NULL || ptr == NULL)
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246 return;
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247 #endif /* PNG_USER_MEM_SUPPORTED */
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248
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249 free(ptr);
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250 }
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251
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252 #ifdef PNG_USER_MEM_SUPPORTED
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253 /* This function is called when the application wants to use another method
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254 * of allocating and freeing memory.
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255 */
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256 void PNGAPI
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257 png_set_mem_fn(png_structrp png_ptr, png_voidp mem_ptr, png_malloc_ptr
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258 malloc_fn, png_free_ptr free_fn)
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259 {
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260 if (png_ptr != NULL)
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261 {
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262 png_ptr->mem_ptr = mem_ptr;
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263 png_ptr->malloc_fn = malloc_fn;
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264 png_ptr->free_fn = free_fn;
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265 }
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266 }
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267
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268 /* This function returns a pointer to the mem_ptr associated with the user
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269 * functions. The application should free any memory associated with this
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270 * pointer before png_write_destroy and png_read_destroy are called.
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271 */
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272 png_voidp PNGAPI
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273 png_get_mem_ptr(png_const_structrp png_ptr)
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274 {
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275 if (png_ptr == NULL)
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276 return NULL;
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277
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278 return png_ptr->mem_ptr;
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279 }
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280 #endif /* PNG_USER_MEM_SUPPORTED */
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281 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */
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