1 |
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2 | /* png.c - location for general purpose libpng functions
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3 | *
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4 | * Copyright (c) 2018-2024 Cosmin Truta
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5 | * Copyright (c) 1998-2002,2004,2006-2018 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 |
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14 | #include "pngpriv.h"
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15 |
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16 | /* Generate a compiler error if there is an old png.h in the search path. */
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17 | typedef png_libpng_version_1_6_42 Your_png_h_is_not_version_1_6_42;
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18 |
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19 | /* Tells libpng that we have already handled the first "num_bytes" bytes
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20 | * of the PNG file signature. If the PNG data is embedded into another
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21 | * stream we can set num_bytes = 8 so that libpng will not attempt to read
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22 | * or write any of the magic bytes before it starts on the IHDR.
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23 | */
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24 |
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25 | #ifdef PNG_READ_SUPPORTED
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26 | void PNGAPI
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27 | png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
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28 | {
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29 | unsigned int nb = (unsigned int)num_bytes;
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30 |
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31 | png_debug(1, "in png_set_sig_bytes");
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32 |
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33 | if (png_ptr == NULL)
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34 | return;
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35 |
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36 | if (num_bytes < 0)
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37 | nb = 0;
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38 |
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39 | if (nb > 8)
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40 | png_error(png_ptr, "Too many bytes for PNG signature");
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41 |
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42 | png_ptr->sig_bytes = (png_byte)nb;
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43 | }
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44 |
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45 | /* Checks whether the supplied bytes match the PNG signature. We allow
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46 | * checking less than the full 8-byte signature so that those apps that
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47 | * already read the first few bytes of a file to determine the file type
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48 | * can simply check the remaining bytes for extra assurance. Returns
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49 | * an integer less than, equal to, or greater than zero if sig is found,
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50 | * respectively, to be less than, to match, or be greater than the correct
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51 | * PNG signature (this is the same behavior as strcmp, memcmp, etc).
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52 | */
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53 | int PNGAPI
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54 | png_sig_cmp(png_const_bytep sig, size_t start, size_t num_to_check)
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55 | {
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56 | static const png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
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57 |
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58 | if (num_to_check > 8)
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59 | num_to_check = 8;
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60 |
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61 | else if (num_to_check < 1)
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62 | return -1;
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63 |
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64 | if (start > 7)
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65 | return -1;
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66 |
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67 | if (start + num_to_check > 8)
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68 | num_to_check = 8 - start;
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69 |
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70 | return memcmp(&sig[start], &png_signature[start], num_to_check);
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71 | }
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72 |
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73 | #endif /* READ */
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74 |
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75 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
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76 | /* Function to allocate memory for zlib */
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77 | PNG_FUNCTION(voidpf /* PRIVATE */,
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78 | png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
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79 | {
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80 | png_alloc_size_t num_bytes = size;
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81 |
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82 | if (png_ptr == NULL)
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83 | return NULL;
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84 |
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85 | if (items >= (~(png_alloc_size_t)0)/size)
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86 | {
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87 | png_warning (png_voidcast(png_structrp, png_ptr),
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88 | "Potential overflow in png_zalloc()");
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89 | return NULL;
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90 | }
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91 |
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92 | num_bytes *= items;
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93 | return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
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94 | }
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95 |
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96 | /* Function to free memory for zlib */
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97 | void /* PRIVATE */
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98 | png_zfree(voidpf png_ptr, voidpf ptr)
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99 | {
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100 | png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
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101 | }
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102 |
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103 | /* Reset the CRC variable to 32 bits of 1's. Care must be taken
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104 | * in case CRC is > 32 bits to leave the top bits 0.
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105 | */
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106 | void /* PRIVATE */
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107 | png_reset_crc(png_structrp png_ptr)
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108 | {
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109 | /* The cast is safe because the crc is a 32-bit value. */
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110 | png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
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111 | }
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112 |
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113 | /* Calculate the CRC over a section of data. We can only pass as
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114 | * much data to this routine as the largest single buffer size. We
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115 | * also check that this data will actually be used before going to the
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116 | * trouble of calculating it.
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117 | */
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118 | void /* PRIVATE */
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119 | png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, size_t length)
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120 | {
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121 | int need_crc = 1;
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122 |
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123 | if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
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124 | {
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125 | if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
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126 | (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
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127 | need_crc = 0;
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128 | }
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129 |
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130 | else /* critical */
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131 | {
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132 | if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
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133 | need_crc = 0;
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134 | }
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135 |
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136 | /* 'uLong' is defined in zlib.h as unsigned long; this means that on some
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137 | * systems it is a 64-bit value. crc32, however, returns 32 bits so the
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138 | * following cast is safe. 'uInt' may be no more than 16 bits, so it is
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139 | * necessary to perform a loop here.
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140 | */
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141 | if (need_crc != 0 && length > 0)
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142 | {
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143 | uLong crc = png_ptr->crc; /* Should never issue a warning */
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144 |
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145 | do
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146 | {
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147 | uInt safe_length = (uInt)length;
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148 | #ifndef __COVERITY__
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149 | if (safe_length == 0)
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150 | safe_length = (uInt)-1; /* evil, but safe */
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151 | #endif
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152 |
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153 | crc = crc32(crc, ptr, safe_length);
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154 |
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155 | /* The following should never issue compiler warnings; if they do the
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156 | * target system has characteristics that will probably violate other
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157 | * assumptions within the libpng code.
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158 | */
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159 | ptr += safe_length;
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160 | length -= safe_length;
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161 | }
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162 | while (length > 0);
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163 |
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164 | /* And the following is always safe because the crc is only 32 bits. */
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165 | png_ptr->crc = (png_uint_32)crc;
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166 | }
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167 | }
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168 |
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169 | /* Check a user supplied version number, called from both read and write
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170 | * functions that create a png_struct.
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171 | */
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172 | int
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173 | png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
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174 | {
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175 | /* Libpng versions 1.0.0 and later are binary compatible if the version
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176 | * string matches through the second '.'; we must recompile any
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177 | * applications that use any older library version.
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178 | */
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179 |
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180 | if (user_png_ver != NULL)
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181 | {
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182 | int i = -1;
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183 | int found_dots = 0;
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184 |
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185 | do
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186 | {
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187 | i++;
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188 | if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
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189 | png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
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190 | if (user_png_ver[i] == '.')
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191 | found_dots++;
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192 | } while (found_dots < 2 && user_png_ver[i] != 0 &&
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193 | PNG_LIBPNG_VER_STRING[i] != 0);
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194 | }
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195 |
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196 | else
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197 | png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
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198 |
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199 | if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
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200 | {
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201 | #ifdef PNG_WARNINGS_SUPPORTED
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202 | size_t pos = 0;
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203 | char m[128];
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204 |
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205 | pos = png_safecat(m, (sizeof m), pos,
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206 | "Application built with libpng-");
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207 | pos = png_safecat(m, (sizeof m), pos, user_png_ver);
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208 | pos = png_safecat(m, (sizeof m), pos, " but running with ");
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209 | pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
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210 | PNG_UNUSED(pos)
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211 |
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212 | png_warning(png_ptr, m);
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213 | #endif
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214 |
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215 | #ifdef PNG_ERROR_NUMBERS_SUPPORTED
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216 | png_ptr->flags = 0;
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217 | #endif
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218 |
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219 | return 0;
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220 | }
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221 |
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222 | /* Success return. */
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223 | return 1;
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224 | }
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225 |
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226 | /* Generic function to create a png_struct for either read or write - this
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227 | * contains the common initialization.
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228 | */
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229 | PNG_FUNCTION(png_structp /* PRIVATE */,
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230 | png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
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231 | png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
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232 | png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
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233 | {
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234 | png_struct create_struct;
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235 | # ifdef PNG_SETJMP_SUPPORTED
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236 | jmp_buf create_jmp_buf;
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237 | # endif
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238 |
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239 | /* This temporary stack-allocated structure is used to provide a place to
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240 | * build enough context to allow the user provided memory allocator (if any)
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241 | * to be called.
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242 | */
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243 | memset(&create_struct, 0, (sizeof create_struct));
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244 |
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245 | /* Added at libpng-1.2.6 */
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246 | # ifdef PNG_USER_LIMITS_SUPPORTED
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247 | create_struct.user_width_max = PNG_USER_WIDTH_MAX;
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248 | create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
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249 |
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250 | # ifdef PNG_USER_CHUNK_CACHE_MAX
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251 | /* Added at libpng-1.2.43 and 1.4.0 */
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252 | create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
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253 | # endif
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254 |
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255 | # ifdef PNG_USER_CHUNK_MALLOC_MAX
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256 | /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
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257 | * in png_struct regardless.
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258 | */
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259 | create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
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260 | # endif
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261 | # endif
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262 |
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263 | /* The following two API calls simply set fields in png_struct, so it is safe
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264 | * to do them now even though error handling is not yet set up.
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265 | */
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266 | # ifdef PNG_USER_MEM_SUPPORTED
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267 | png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
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268 | # else
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269 | PNG_UNUSED(mem_ptr)
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270 | PNG_UNUSED(malloc_fn)
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271 | PNG_UNUSED(free_fn)
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272 | # endif
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273 |
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274 | /* (*error_fn) can return control to the caller after the error_ptr is set,
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275 | * this will result in a memory leak unless the error_fn does something
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276 | * extremely sophisticated. The design lacks merit but is implicit in the
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277 | * API.
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278 | */
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279 | png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
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280 |
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281 | # ifdef PNG_SETJMP_SUPPORTED
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282 | if (!setjmp(create_jmp_buf))
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283 | # endif
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284 | {
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285 | # ifdef PNG_SETJMP_SUPPORTED
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286 | /* Temporarily fake out the longjmp information until we have
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287 | * successfully completed this function. This only works if we have
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288 | * setjmp() support compiled in, but it is safe - this stuff should
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289 | * never happen.
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290 | */
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291 | create_struct.jmp_buf_ptr = &create_jmp_buf;
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292 | create_struct.jmp_buf_size = 0; /*stack allocation*/
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293 | create_struct.longjmp_fn = longjmp;
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294 | # endif
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295 | /* Call the general version checker (shared with read and write code):
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296 | */
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297 | if (png_user_version_check(&create_struct, user_png_ver) != 0)
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298 | {
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299 | png_structrp png_ptr = png_voidcast(png_structrp,
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300 | png_malloc_warn(&create_struct, (sizeof *png_ptr)));
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301 |
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302 | if (png_ptr != NULL)
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303 | {
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304 | /* png_ptr->zstream holds a back-pointer to the png_struct, so
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305 | * this can only be done now:
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306 | */
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307 | create_struct.zstream.zalloc = png_zalloc;
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308 | create_struct.zstream.zfree = png_zfree;
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309 | create_struct.zstream.opaque = png_ptr;
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310 |
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311 | # ifdef PNG_SETJMP_SUPPORTED
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312 | /* Eliminate the local error handling: */
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313 | create_struct.jmp_buf_ptr = NULL;
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314 | create_struct.jmp_buf_size = 0;
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315 | create_struct.longjmp_fn = 0;
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316 | # endif
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317 |
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318 | *png_ptr = create_struct;
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319 |
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320 | /* This is the successful return point */
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321 | return png_ptr;
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322 | }
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323 | }
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324 | }
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325 |
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326 | /* A longjmp because of a bug in the application storage allocator or a
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327 | * simple failure to allocate the png_struct.
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328 | */
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329 | return NULL;
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330 | }
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331 |
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332 | /* Allocate the memory for an info_struct for the application. */
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333 | PNG_FUNCTION(png_infop,PNGAPI
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334 | png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
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335 | {
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336 | png_inforp info_ptr;
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337 |
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338 | png_debug(1, "in png_create_info_struct");
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339 |
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340 | if (png_ptr == NULL)
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341 | return NULL;
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342 |
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343 | /* Use the internal API that does not (or at least should not) error out, so
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344 | * that this call always returns ok. The application typically sets up the
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345 | * error handling *after* creating the info_struct because this is the way it
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346 | * has always been done in 'example.c'.
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347 | */
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348 | info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
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349 | (sizeof *info_ptr)));
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350 |
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351 | if (info_ptr != NULL)
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352 | memset(info_ptr, 0, (sizeof *info_ptr));
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353 |
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354 | return info_ptr;
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355 | }
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356 |
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357 | /* This function frees the memory associated with a single info struct.
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358 | * Normally, one would use either png_destroy_read_struct() or
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359 | * png_destroy_write_struct() to free an info struct, but this may be
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360 | * useful for some applications. From libpng 1.6.0 this function is also used
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361 | * internally to implement the png_info release part of the 'struct' destroy
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362 | * APIs. This ensures that all possible approaches free the same data (all of
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363 | * it).
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364 | */
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365 | void PNGAPI
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366 | png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
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367 | {
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368 | png_inforp info_ptr = NULL;
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369 |
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370 | png_debug(1, "in png_destroy_info_struct");
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371 |
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372 | if (png_ptr == NULL)
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373 | return;
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374 |
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375 | if (info_ptr_ptr != NULL)
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376 | info_ptr = *info_ptr_ptr;
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377 |
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378 | if (info_ptr != NULL)
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379 | {
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380 | /* Do this first in case of an error below; if the app implements its own
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381 | * memory management this can lead to png_free calling png_error, which
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382 | * will abort this routine and return control to the app error handler.
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383 | * An infinite loop may result if it then tries to free the same info
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384 | * ptr.
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385 | */
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386 | *info_ptr_ptr = NULL;
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387 |
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388 | png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
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389 | memset(info_ptr, 0, (sizeof *info_ptr));
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390 | png_free(png_ptr, info_ptr);
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391 | }
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392 | }
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393 |
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394 | /* Initialize the info structure. This is now an internal function (0.89)
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395 | * and applications using it are urged to use png_create_info_struct()
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396 | * instead. Use deprecated in 1.6.0, internal use removed (used internally it
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397 | * is just a memset).
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398 | *
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399 | * NOTE: it is almost inconceivable that this API is used because it bypasses
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400 | * the user-memory mechanism and the user error handling/warning mechanisms in
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401 | * those cases where it does anything other than a memset.
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402 | */
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403 | PNG_FUNCTION(void,PNGAPI
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404 | png_info_init_3,(png_infopp ptr_ptr, size_t png_info_struct_size),
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405 | PNG_DEPRECATED)
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406 | {
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407 | png_inforp info_ptr = *ptr_ptr;
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408 |
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409 | png_debug(1, "in png_info_init_3");
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410 |
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411 | if (info_ptr == NULL)
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412 | return;
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413 |
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414 | if ((sizeof (png_info)) > png_info_struct_size)
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415 | {
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416 | *ptr_ptr = NULL;
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417 | /* The following line is why this API should not be used: */
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418 | free(info_ptr);
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419 | info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
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420 | (sizeof *info_ptr)));
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421 | if (info_ptr == NULL)
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422 | return;
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423 | *ptr_ptr = info_ptr;
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424 | }
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425 |
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426 | /* Set everything to 0 */
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427 | memset(info_ptr, 0, (sizeof *info_ptr));
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428 | }
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429 |
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430 | void PNGAPI
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431 | png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
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432 | int freer, png_uint_32 mask)
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433 | {
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434 | png_debug(1, "in png_data_freer");
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435 |
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436 | if (png_ptr == NULL || info_ptr == NULL)
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437 | return;
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438 |
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439 | if (freer == PNG_DESTROY_WILL_FREE_DATA)
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440 | info_ptr->free_me |= mask;
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441 |
|
---|
442 | else if (freer == PNG_USER_WILL_FREE_DATA)
|
---|
443 | info_ptr->free_me &= ~mask;
|
---|
444 |
|
---|
445 | else
|
---|
446 | png_error(png_ptr, "Unknown freer parameter in png_data_freer");
|
---|
447 | }
|
---|
448 |
|
---|
449 | void PNGAPI
|
---|
450 | png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
|
---|
451 | int num)
|
---|
452 | {
|
---|
453 | png_debug(1, "in png_free_data");
|
---|
454 |
|
---|
455 | if (png_ptr == NULL || info_ptr == NULL)
|
---|
456 | return;
|
---|
457 |
|
---|
458 | #ifdef PNG_TEXT_SUPPORTED
|
---|
459 | /* Free text item num or (if num == -1) all text items */
|
---|
460 | if (info_ptr->text != NULL &&
|
---|
461 | ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
|
---|
462 | {
|
---|
463 | if (num != -1)
|
---|
464 | {
|
---|
465 | png_free(png_ptr, info_ptr->text[num].key);
|
---|
466 | info_ptr->text[num].key = NULL;
|
---|
467 | }
|
---|
468 |
|
---|
469 | else
|
---|
470 | {
|
---|
471 | int i;
|
---|
472 |
|
---|
473 | for (i = 0; i < info_ptr->num_text; i++)
|
---|
474 | png_free(png_ptr, info_ptr->text[i].key);
|
---|
475 |
|
---|
476 | png_free(png_ptr, info_ptr->text);
|
---|
477 | info_ptr->text = NULL;
|
---|
478 | info_ptr->num_text = 0;
|
---|
479 | info_ptr->max_text = 0;
|
---|
480 | }
|
---|
481 | }
|
---|
482 | #endif
|
---|
483 |
|
---|
484 | #ifdef PNG_tRNS_SUPPORTED
|
---|
485 | /* Free any tRNS entry */
|
---|
486 | if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
|
---|
487 | {
|
---|
488 | info_ptr->valid &= ~PNG_INFO_tRNS;
|
---|
489 | png_free(png_ptr, info_ptr->trans_alpha);
|
---|
490 | info_ptr->trans_alpha = NULL;
|
---|
491 | info_ptr->num_trans = 0;
|
---|
492 | }
|
---|
493 | #endif
|
---|
494 |
|
---|
495 | #ifdef PNG_sCAL_SUPPORTED
|
---|
496 | /* Free any sCAL entry */
|
---|
497 | if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
|
---|
498 | {
|
---|
499 | png_free(png_ptr, info_ptr->scal_s_width);
|
---|
500 | png_free(png_ptr, info_ptr->scal_s_height);
|
---|
501 | info_ptr->scal_s_width = NULL;
|
---|
502 | info_ptr->scal_s_height = NULL;
|
---|
503 | info_ptr->valid &= ~PNG_INFO_sCAL;
|
---|
504 | }
|
---|
505 | #endif
|
---|
506 |
|
---|
507 | #ifdef PNG_pCAL_SUPPORTED
|
---|
508 | /* Free any pCAL entry */
|
---|
509 | if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
|
---|
510 | {
|
---|
511 | png_free(png_ptr, info_ptr->pcal_purpose);
|
---|
512 | png_free(png_ptr, info_ptr->pcal_units);
|
---|
513 | info_ptr->pcal_purpose = NULL;
|
---|
514 | info_ptr->pcal_units = NULL;
|
---|
515 |
|
---|
516 | if (info_ptr->pcal_params != NULL)
|
---|
517 | {
|
---|
518 | int i;
|
---|
519 |
|
---|
520 | for (i = 0; i < info_ptr->pcal_nparams; i++)
|
---|
521 | png_free(png_ptr, info_ptr->pcal_params[i]);
|
---|
522 |
|
---|
523 | png_free(png_ptr, info_ptr->pcal_params);
|
---|
524 | info_ptr->pcal_params = NULL;
|
---|
525 | }
|
---|
526 | info_ptr->valid &= ~PNG_INFO_pCAL;
|
---|
527 | }
|
---|
528 | #endif
|
---|
529 |
|
---|
530 | #ifdef PNG_iCCP_SUPPORTED
|
---|
531 | /* Free any profile entry */
|
---|
532 | if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
|
---|
533 | {
|
---|
534 | png_free(png_ptr, info_ptr->iccp_name);
|
---|
535 | png_free(png_ptr, info_ptr->iccp_profile);
|
---|
536 | info_ptr->iccp_name = NULL;
|
---|
537 | info_ptr->iccp_profile = NULL;
|
---|
538 | info_ptr->valid &= ~PNG_INFO_iCCP;
|
---|
539 | }
|
---|
540 | #endif
|
---|
541 |
|
---|
542 | #ifdef PNG_sPLT_SUPPORTED
|
---|
543 | /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
|
---|
544 | if (info_ptr->splt_palettes != NULL &&
|
---|
545 | ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
|
---|
546 | {
|
---|
547 | if (num != -1)
|
---|
548 | {
|
---|
549 | png_free(png_ptr, info_ptr->splt_palettes[num].name);
|
---|
550 | png_free(png_ptr, info_ptr->splt_palettes[num].entries);
|
---|
551 | info_ptr->splt_palettes[num].name = NULL;
|
---|
552 | info_ptr->splt_palettes[num].entries = NULL;
|
---|
553 | }
|
---|
554 |
|
---|
555 | else
|
---|
556 | {
|
---|
557 | int i;
|
---|
558 |
|
---|
559 | for (i = 0; i < info_ptr->splt_palettes_num; i++)
|
---|
560 | {
|
---|
561 | png_free(png_ptr, info_ptr->splt_palettes[i].name);
|
---|
562 | png_free(png_ptr, info_ptr->splt_palettes[i].entries);
|
---|
563 | }
|
---|
564 |
|
---|
565 | png_free(png_ptr, info_ptr->splt_palettes);
|
---|
566 | info_ptr->splt_palettes = NULL;
|
---|
567 | info_ptr->splt_palettes_num = 0;
|
---|
568 | info_ptr->valid &= ~PNG_INFO_sPLT;
|
---|
569 | }
|
---|
570 | }
|
---|
571 | #endif
|
---|
572 |
|
---|
573 | #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
|
---|
574 | if (info_ptr->unknown_chunks != NULL &&
|
---|
575 | ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
|
---|
576 | {
|
---|
577 | if (num != -1)
|
---|
578 | {
|
---|
579 | png_free(png_ptr, info_ptr->unknown_chunks[num].data);
|
---|
580 | info_ptr->unknown_chunks[num].data = NULL;
|
---|
581 | }
|
---|
582 |
|
---|
583 | else
|
---|
584 | {
|
---|
585 | int i;
|
---|
586 |
|
---|
587 | for (i = 0; i < info_ptr->unknown_chunks_num; i++)
|
---|
588 | png_free(png_ptr, info_ptr->unknown_chunks[i].data);
|
---|
589 |
|
---|
590 | png_free(png_ptr, info_ptr->unknown_chunks);
|
---|
591 | info_ptr->unknown_chunks = NULL;
|
---|
592 | info_ptr->unknown_chunks_num = 0;
|
---|
593 | }
|
---|
594 | }
|
---|
595 | #endif
|
---|
596 |
|
---|
597 | #ifdef PNG_eXIf_SUPPORTED
|
---|
598 | /* Free any eXIf entry */
|
---|
599 | if (((mask & PNG_FREE_EXIF) & info_ptr->free_me) != 0)
|
---|
600 | {
|
---|
601 | # ifdef PNG_READ_eXIf_SUPPORTED
|
---|
602 | if (info_ptr->eXIf_buf)
|
---|
603 | {
|
---|
604 | png_free(png_ptr, info_ptr->eXIf_buf);
|
---|
605 | info_ptr->eXIf_buf = NULL;
|
---|
606 | }
|
---|
607 | # endif
|
---|
608 | if (info_ptr->exif)
|
---|
609 | {
|
---|
610 | png_free(png_ptr, info_ptr->exif);
|
---|
611 | info_ptr->exif = NULL;
|
---|
612 | }
|
---|
613 | info_ptr->valid &= ~PNG_INFO_eXIf;
|
---|
614 | }
|
---|
615 | #endif
|
---|
616 |
|
---|
617 | #ifdef PNG_hIST_SUPPORTED
|
---|
618 | /* Free any hIST entry */
|
---|
619 | if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
|
---|
620 | {
|
---|
621 | png_free(png_ptr, info_ptr->hist);
|
---|
622 | info_ptr->hist = NULL;
|
---|
623 | info_ptr->valid &= ~PNG_INFO_hIST;
|
---|
624 | }
|
---|
625 | #endif
|
---|
626 |
|
---|
627 | /* Free any PLTE entry that was internally allocated */
|
---|
628 | if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
|
---|
629 | {
|
---|
630 | png_free(png_ptr, info_ptr->palette);
|
---|
631 | info_ptr->palette = NULL;
|
---|
632 | info_ptr->valid &= ~PNG_INFO_PLTE;
|
---|
633 | info_ptr->num_palette = 0;
|
---|
634 | }
|
---|
635 |
|
---|
636 | #ifdef PNG_INFO_IMAGE_SUPPORTED
|
---|
637 | /* Free any image bits attached to the info structure */
|
---|
638 | if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
|
---|
639 | {
|
---|
640 | if (info_ptr->row_pointers != NULL)
|
---|
641 | {
|
---|
642 | png_uint_32 row;
|
---|
643 | for (row = 0; row < info_ptr->height; row++)
|
---|
644 | png_free(png_ptr, info_ptr->row_pointers[row]);
|
---|
645 |
|
---|
646 | png_free(png_ptr, info_ptr->row_pointers);
|
---|
647 | info_ptr->row_pointers = NULL;
|
---|
648 | }
|
---|
649 | info_ptr->valid &= ~PNG_INFO_IDAT;
|
---|
650 | }
|
---|
651 | #endif
|
---|
652 |
|
---|
653 | if (num != -1)
|
---|
654 | mask &= ~PNG_FREE_MUL;
|
---|
655 |
|
---|
656 | info_ptr->free_me &= ~mask;
|
---|
657 | }
|
---|
658 | #endif /* READ || WRITE */
|
---|
659 |
|
---|
660 | /* This function returns a pointer to the io_ptr associated with the user
|
---|
661 | * functions. The application should free any memory associated with this
|
---|
662 | * pointer before png_write_destroy() or png_read_destroy() are called.
|
---|
663 | */
|
---|
664 | png_voidp PNGAPI
|
---|
665 | png_get_io_ptr(png_const_structrp png_ptr)
|
---|
666 | {
|
---|
667 | if (png_ptr == NULL)
|
---|
668 | return NULL;
|
---|
669 |
|
---|
670 | return png_ptr->io_ptr;
|
---|
671 | }
|
---|
672 |
|
---|
673 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
|
---|
674 | # ifdef PNG_STDIO_SUPPORTED
|
---|
675 | /* Initialize the default input/output functions for the PNG file. If you
|
---|
676 | * use your own read or write routines, you can call either png_set_read_fn()
|
---|
677 | * or png_set_write_fn() instead of png_init_io(). If you have defined
|
---|
678 | * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
|
---|
679 | * function of your own because "FILE *" isn't necessarily available.
|
---|
680 | */
|
---|
681 | void PNGAPI
|
---|
682 | png_init_io(png_structrp png_ptr, png_FILE_p fp)
|
---|
683 | {
|
---|
684 | png_debug(1, "in png_init_io");
|
---|
685 |
|
---|
686 | if (png_ptr == NULL)
|
---|
687 | return;
|
---|
688 |
|
---|
689 | png_ptr->io_ptr = (png_voidp)fp;
|
---|
690 | }
|
---|
691 | # endif
|
---|
692 |
|
---|
693 | # ifdef PNG_SAVE_INT_32_SUPPORTED
|
---|
694 | /* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
|
---|
695 | * defines a cast of a signed integer to an unsigned integer either to preserve
|
---|
696 | * the value, if it is positive, or to calculate:
|
---|
697 | *
|
---|
698 | * (UNSIGNED_MAX+1) + integer
|
---|
699 | *
|
---|
700 | * Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
|
---|
701 | * negative integral value is added the result will be an unsigned value
|
---|
702 | * corresponding to the 2's complement representation.
|
---|
703 | */
|
---|
704 | void PNGAPI
|
---|
705 | png_save_int_32(png_bytep buf, png_int_32 i)
|
---|
706 | {
|
---|
707 | png_save_uint_32(buf, (png_uint_32)i);
|
---|
708 | }
|
---|
709 | # endif
|
---|
710 |
|
---|
711 | # ifdef PNG_TIME_RFC1123_SUPPORTED
|
---|
712 | /* Convert the supplied time into an RFC 1123 string suitable for use in
|
---|
713 | * a "Creation Time" or other text-based time string.
|
---|
714 | */
|
---|
715 | int PNGAPI
|
---|
716 | png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
|
---|
717 | {
|
---|
718 | static const char short_months[12][4] =
|
---|
719 | {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
|
---|
720 | "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
|
---|
721 |
|
---|
722 | if (out == NULL)
|
---|
723 | return 0;
|
---|
724 |
|
---|
725 | if (ptime->year > 9999 /* RFC1123 limitation */ ||
|
---|
726 | ptime->month == 0 || ptime->month > 12 ||
|
---|
727 | ptime->day == 0 || ptime->day > 31 ||
|
---|
728 | ptime->hour > 23 || ptime->minute > 59 ||
|
---|
729 | ptime->second > 60)
|
---|
730 | return 0;
|
---|
731 |
|
---|
732 | {
|
---|
733 | size_t pos = 0;
|
---|
734 | char number_buf[5] = {0, 0, 0, 0, 0}; /* enough for a four-digit year */
|
---|
735 |
|
---|
736 | # define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
|
---|
737 | # define APPEND_NUMBER(format, value)\
|
---|
738 | APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
|
---|
739 | # define APPEND(ch) if (pos < 28) out[pos++] = (ch)
|
---|
740 |
|
---|
741 | APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
|
---|
742 | APPEND(' ');
|
---|
743 | APPEND_STRING(short_months[(ptime->month - 1)]);
|
---|
744 | APPEND(' ');
|
---|
745 | APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
|
---|
746 | APPEND(' ');
|
---|
747 | APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
|
---|
748 | APPEND(':');
|
---|
749 | APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
|
---|
750 | APPEND(':');
|
---|
751 | APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
|
---|
752 | APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
|
---|
753 | PNG_UNUSED (pos)
|
---|
754 |
|
---|
755 | # undef APPEND
|
---|
756 | # undef APPEND_NUMBER
|
---|
757 | # undef APPEND_STRING
|
---|
758 | }
|
---|
759 |
|
---|
760 | return 1;
|
---|
761 | }
|
---|
762 |
|
---|
763 | # if PNG_LIBPNG_VER < 10700
|
---|
764 | /* To do: remove the following from libpng-1.7 */
|
---|
765 | /* Original API that uses a private buffer in png_struct.
|
---|
766 | * Deprecated because it causes png_struct to carry a spurious temporary
|
---|
767 | * buffer (png_struct::time_buffer), better to have the caller pass this in.
|
---|
768 | */
|
---|
769 | png_const_charp PNGAPI
|
---|
770 | png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
|
---|
771 | {
|
---|
772 | if (png_ptr != NULL)
|
---|
773 | {
|
---|
774 | /* The only failure above if png_ptr != NULL is from an invalid ptime */
|
---|
775 | if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
|
---|
776 | png_warning(png_ptr, "Ignoring invalid time value");
|
---|
777 |
|
---|
778 | else
|
---|
779 | return png_ptr->time_buffer;
|
---|
780 | }
|
---|
781 |
|
---|
782 | return NULL;
|
---|
783 | }
|
---|
784 | # endif /* LIBPNG_VER < 10700 */
|
---|
785 | # endif /* TIME_RFC1123 */
|
---|
786 |
|
---|
787 | #endif /* READ || WRITE */
|
---|
788 |
|
---|
789 | png_const_charp PNGAPI
|
---|
790 | png_get_copyright(png_const_structrp png_ptr)
|
---|
791 | {
|
---|
792 | PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
---|
793 | #ifdef PNG_STRING_COPYRIGHT
|
---|
794 | return PNG_STRING_COPYRIGHT
|
---|
795 | #else
|
---|
796 | return PNG_STRING_NEWLINE \
|
---|
797 | "libpng version 1.6.42" PNG_STRING_NEWLINE \
|
---|
798 | "Copyright (c) 2018-2024 Cosmin Truta" PNG_STRING_NEWLINE \
|
---|
799 | "Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson" \
|
---|
800 | PNG_STRING_NEWLINE \
|
---|
801 | "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
|
---|
802 | "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
|
---|
803 | PNG_STRING_NEWLINE;
|
---|
804 | #endif
|
---|
805 | }
|
---|
806 |
|
---|
807 | /* The following return the library version as a short string in the
|
---|
808 | * format 1.0.0 through 99.99.99zz. To get the version of *.h files
|
---|
809 | * used with your application, print out PNG_LIBPNG_VER_STRING, which
|
---|
810 | * is defined in png.h.
|
---|
811 | * Note: now there is no difference between png_get_libpng_ver() and
|
---|
812 | * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
|
---|
813 | * it is guaranteed that png.c uses the correct version of png.h.
|
---|
814 | */
|
---|
815 | png_const_charp PNGAPI
|
---|
816 | png_get_libpng_ver(png_const_structrp png_ptr)
|
---|
817 | {
|
---|
818 | /* Version of *.c files used when building libpng */
|
---|
819 | return png_get_header_ver(png_ptr);
|
---|
820 | }
|
---|
821 |
|
---|
822 | png_const_charp PNGAPI
|
---|
823 | png_get_header_ver(png_const_structrp png_ptr)
|
---|
824 | {
|
---|
825 | /* Version of *.h files used when building libpng */
|
---|
826 | PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
---|
827 | return PNG_LIBPNG_VER_STRING;
|
---|
828 | }
|
---|
829 |
|
---|
830 | png_const_charp PNGAPI
|
---|
831 | png_get_header_version(png_const_structrp png_ptr)
|
---|
832 | {
|
---|
833 | /* Returns longer string containing both version and date */
|
---|
834 | PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
---|
835 | #ifdef __STDC__
|
---|
836 | return PNG_HEADER_VERSION_STRING
|
---|
837 | # ifndef PNG_READ_SUPPORTED
|
---|
838 | " (NO READ SUPPORT)"
|
---|
839 | # endif
|
---|
840 | PNG_STRING_NEWLINE;
|
---|
841 | #else
|
---|
842 | return PNG_HEADER_VERSION_STRING;
|
---|
843 | #endif
|
---|
844 | }
|
---|
845 |
|
---|
846 | #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
|
---|
847 | /* NOTE: this routine is not used internally! */
|
---|
848 | /* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
|
---|
849 | * large of png_color. This lets grayscale images be treated as
|
---|
850 | * paletted. Most useful for gamma correction and simplification
|
---|
851 | * of code. This API is not used internally.
|
---|
852 | */
|
---|
853 | void PNGAPI
|
---|
854 | png_build_grayscale_palette(int bit_depth, png_colorp palette)
|
---|
855 | {
|
---|
856 | int num_palette;
|
---|
857 | int color_inc;
|
---|
858 | int i;
|
---|
859 | int v;
|
---|
860 |
|
---|
861 | png_debug(1, "in png_do_build_grayscale_palette");
|
---|
862 |
|
---|
863 | if (palette == NULL)
|
---|
864 | return;
|
---|
865 |
|
---|
866 | switch (bit_depth)
|
---|
867 | {
|
---|
868 | case 1:
|
---|
869 | num_palette = 2;
|
---|
870 | color_inc = 0xff;
|
---|
871 | break;
|
---|
872 |
|
---|
873 | case 2:
|
---|
874 | num_palette = 4;
|
---|
875 | color_inc = 0x55;
|
---|
876 | break;
|
---|
877 |
|
---|
878 | case 4:
|
---|
879 | num_palette = 16;
|
---|
880 | color_inc = 0x11;
|
---|
881 | break;
|
---|
882 |
|
---|
883 | case 8:
|
---|
884 | num_palette = 256;
|
---|
885 | color_inc = 1;
|
---|
886 | break;
|
---|
887 |
|
---|
888 | default:
|
---|
889 | num_palette = 0;
|
---|
890 | color_inc = 0;
|
---|
891 | break;
|
---|
892 | }
|
---|
893 |
|
---|
894 | for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
|
---|
895 | {
|
---|
896 | palette[i].red = (png_byte)(v & 0xff);
|
---|
897 | palette[i].green = (png_byte)(v & 0xff);
|
---|
898 | palette[i].blue = (png_byte)(v & 0xff);
|
---|
899 | }
|
---|
900 | }
|
---|
901 | #endif
|
---|
902 |
|
---|
903 | #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
|
---|
904 | int PNGAPI
|
---|
905 | png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
|
---|
906 | {
|
---|
907 | /* Check chunk_name and return "keep" value if it's on the list, else 0 */
|
---|
908 | png_const_bytep p, p_end;
|
---|
909 |
|
---|
910 | if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
|
---|
911 | return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
---|
912 |
|
---|
913 | p_end = png_ptr->chunk_list;
|
---|
914 | p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
|
---|
915 |
|
---|
916 | /* The code is the fifth byte after each four byte string. Historically this
|
---|
917 | * code was always searched from the end of the list, this is no longer
|
---|
918 | * necessary because the 'set' routine handles duplicate entries correctly.
|
---|
919 | */
|
---|
920 | do /* num_chunk_list > 0, so at least one */
|
---|
921 | {
|
---|
922 | p -= 5;
|
---|
923 |
|
---|
924 | if (memcmp(chunk_name, p, 4) == 0)
|
---|
925 | return p[4];
|
---|
926 | }
|
---|
927 | while (p > p_end);
|
---|
928 |
|
---|
929 | /* This means that known chunks should be processed and unknown chunks should
|
---|
930 | * be handled according to the value of png_ptr->unknown_default; this can be
|
---|
931 | * confusing because, as a result, there are two levels of defaulting for
|
---|
932 | * unknown chunks.
|
---|
933 | */
|
---|
934 | return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
---|
935 | }
|
---|
936 |
|
---|
937 | #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
|
---|
938 | defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
|
---|
939 | int /* PRIVATE */
|
---|
940 | png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
|
---|
941 | {
|
---|
942 | png_byte chunk_string[5];
|
---|
943 |
|
---|
944 | PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
|
---|
945 | return png_handle_as_unknown(png_ptr, chunk_string);
|
---|
946 | }
|
---|
947 | #endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
|
---|
948 | #endif /* SET_UNKNOWN_CHUNKS */
|
---|
949 |
|
---|
950 | #ifdef PNG_READ_SUPPORTED
|
---|
951 | /* This function, added to libpng-1.0.6g, is untested. */
|
---|
952 | int PNGAPI
|
---|
953 | png_reset_zstream(png_structrp png_ptr)
|
---|
954 | {
|
---|
955 | if (png_ptr == NULL)
|
---|
956 | return Z_STREAM_ERROR;
|
---|
957 |
|
---|
958 | /* WARNING: this resets the window bits to the maximum! */
|
---|
959 | return inflateReset(&png_ptr->zstream);
|
---|
960 | }
|
---|
961 | #endif /* READ */
|
---|
962 |
|
---|
963 | /* This function was added to libpng-1.0.7 */
|
---|
964 | png_uint_32 PNGAPI
|
---|
965 | png_access_version_number(void)
|
---|
966 | {
|
---|
967 | /* Version of *.c files used when building libpng */
|
---|
968 | return (png_uint_32)PNG_LIBPNG_VER;
|
---|
969 | }
|
---|
970 |
|
---|
971 | #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
|
---|
972 | /* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
|
---|
973 | * If it doesn't 'ret' is used to set it to something appropriate, even in cases
|
---|
974 | * like Z_OK or Z_STREAM_END where the error code is apparently a success code.
|
---|
975 | */
|
---|
976 | void /* PRIVATE */
|
---|
977 | png_zstream_error(png_structrp png_ptr, int ret)
|
---|
978 | {
|
---|
979 | /* Translate 'ret' into an appropriate error string, priority is given to the
|
---|
980 | * one in zstream if set. This always returns a string, even in cases like
|
---|
981 | * Z_OK or Z_STREAM_END where the error code is a success code.
|
---|
982 | */
|
---|
983 | if (png_ptr->zstream.msg == NULL) switch (ret)
|
---|
984 | {
|
---|
985 | default:
|
---|
986 | case Z_OK:
|
---|
987 | png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
|
---|
988 | break;
|
---|
989 |
|
---|
990 | case Z_STREAM_END:
|
---|
991 | /* Normal exit */
|
---|
992 | png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
|
---|
993 | break;
|
---|
994 |
|
---|
995 | case Z_NEED_DICT:
|
---|
996 | /* This means the deflate stream did not have a dictionary; this
|
---|
997 | * indicates a bogus PNG.
|
---|
998 | */
|
---|
999 | png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
|
---|
1000 | break;
|
---|
1001 |
|
---|
1002 | case Z_ERRNO:
|
---|
1003 | /* gz APIs only: should not happen */
|
---|
1004 | png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
|
---|
1005 | break;
|
---|
1006 |
|
---|
1007 | case Z_STREAM_ERROR:
|
---|
1008 | /* internal libpng error */
|
---|
1009 | png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
|
---|
1010 | break;
|
---|
1011 |
|
---|
1012 | case Z_DATA_ERROR:
|
---|
1013 | png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
|
---|
1014 | break;
|
---|
1015 |
|
---|
1016 | case Z_MEM_ERROR:
|
---|
1017 | png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
|
---|
1018 | break;
|
---|
1019 |
|
---|
1020 | case Z_BUF_ERROR:
|
---|
1021 | /* End of input or output; not a problem if the caller is doing
|
---|
1022 | * incremental read or write.
|
---|
1023 | */
|
---|
1024 | png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
|
---|
1025 | break;
|
---|
1026 |
|
---|
1027 | case Z_VERSION_ERROR:
|
---|
1028 | png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
|
---|
1029 | break;
|
---|
1030 |
|
---|
1031 | case PNG_UNEXPECTED_ZLIB_RETURN:
|
---|
1032 | /* Compile errors here mean that zlib now uses the value co-opted in
|
---|
1033 | * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
|
---|
1034 | * and change pngpriv.h. Note that this message is "... return",
|
---|
1035 | * whereas the default/Z_OK one is "... return code".
|
---|
1036 | */
|
---|
1037 | png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
|
---|
1038 | break;
|
---|
1039 | }
|
---|
1040 | }
|
---|
1041 |
|
---|
1042 | /* png_convert_size: a PNGAPI but no longer in png.h, so deleted
|
---|
1043 | * at libpng 1.5.5!
|
---|
1044 | */
|
---|
1045 |
|
---|
1046 | /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
|
---|
1047 | #ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
|
---|
1048 | static int
|
---|
1049 | png_colorspace_check_gamma(png_const_structrp png_ptr,
|
---|
1050 | png_colorspacerp colorspace, png_fixed_point gAMA, int from)
|
---|
1051 | /* This is called to check a new gamma value against an existing one. The
|
---|
1052 | * routine returns false if the new gamma value should not be written.
|
---|
1053 | *
|
---|
1054 | * 'from' says where the new gamma value comes from:
|
---|
1055 | *
|
---|
1056 | * 0: the new gamma value is the libpng estimate for an ICC profile
|
---|
1057 | * 1: the new gamma value comes from a gAMA chunk
|
---|
1058 | * 2: the new gamma value comes from an sRGB chunk
|
---|
1059 | */
|
---|
1060 | {
|
---|
1061 | png_fixed_point gtest;
|
---|
1062 |
|
---|
1063 | if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
|
---|
1064 | (png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
|
---|
1065 | png_gamma_significant(gtest) != 0))
|
---|
1066 | {
|
---|
1067 | /* Either this is an sRGB image, in which case the calculated gamma
|
---|
1068 | * approximation should match, or this is an image with a profile and the
|
---|
1069 | * value libpng calculates for the gamma of the profile does not match the
|
---|
1070 | * value recorded in the file. The former, sRGB, case is an error, the
|
---|
1071 | * latter is just a warning.
|
---|
1072 | */
|
---|
1073 | if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
|
---|
1074 | {
|
---|
1075 | png_chunk_report(png_ptr, "gamma value does not match sRGB",
|
---|
1076 | PNG_CHUNK_ERROR);
|
---|
1077 | /* Do not overwrite an sRGB value */
|
---|
1078 | return from == 2;
|
---|
1079 | }
|
---|
1080 |
|
---|
1081 | else /* sRGB tag not involved */
|
---|
1082 | {
|
---|
1083 | png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
|
---|
1084 | PNG_CHUNK_WARNING);
|
---|
1085 | return from == 1;
|
---|
1086 | }
|
---|
1087 | }
|
---|
1088 |
|
---|
1089 | return 1;
|
---|
1090 | }
|
---|
1091 |
|
---|
1092 | void /* PRIVATE */
|
---|
1093 | png_colorspace_set_gamma(png_const_structrp png_ptr,
|
---|
1094 | png_colorspacerp colorspace, png_fixed_point gAMA)
|
---|
1095 | {
|
---|
1096 | /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
|
---|
1097 | * occur. Since the fixed point representation is asymmetrical it is
|
---|
1098 | * possible for 1/gamma to overflow the limit of 21474 and this means the
|
---|
1099 | * gamma value must be at least 5/100000 and hence at most 20000.0. For
|
---|
1100 | * safety the limits here are a little narrower. The values are 0.00016 to
|
---|
1101 | * 6250.0, which are truly ridiculous gamma values (and will produce
|
---|
1102 | * displays that are all black or all white.)
|
---|
1103 | *
|
---|
1104 | * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
|
---|
1105 | * handling code, which only required the value to be >0.
|
---|
1106 | */
|
---|
1107 | png_const_charp errmsg;
|
---|
1108 |
|
---|
1109 | if (gAMA < 16 || gAMA > 625000000)
|
---|
1110 | errmsg = "gamma value out of range";
|
---|
1111 |
|
---|
1112 | # ifdef PNG_READ_gAMA_SUPPORTED
|
---|
1113 | /* Allow the application to set the gamma value more than once */
|
---|
1114 | else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
|
---|
1115 | (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
|
---|
1116 | errmsg = "duplicate";
|
---|
1117 | # endif
|
---|
1118 |
|
---|
1119 | /* Do nothing if the colorspace is already invalid */
|
---|
1120 | else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
---|
1121 | return;
|
---|
1122 |
|
---|
1123 | else
|
---|
1124 | {
|
---|
1125 | if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
|
---|
1126 | 1/*from gAMA*/) != 0)
|
---|
1127 | {
|
---|
1128 | /* Store this gamma value. */
|
---|
1129 | colorspace->gamma = gAMA;
|
---|
1130 | colorspace->flags |=
|
---|
1131 | (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
|
---|
1132 | }
|
---|
1133 |
|
---|
1134 | /* At present if the check_gamma test fails the gamma of the colorspace is
|
---|
1135 | * not updated however the colorspace is not invalidated. This
|
---|
1136 | * corresponds to the case where the existing gamma comes from an sRGB
|
---|
1137 | * chunk or profile. An error message has already been output.
|
---|
1138 | */
|
---|
1139 | return;
|
---|
1140 | }
|
---|
1141 |
|
---|
1142 | /* Error exit - errmsg has been set. */
|
---|
1143 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1144 | png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
|
---|
1145 | }
|
---|
1146 |
|
---|
1147 | void /* PRIVATE */
|
---|
1148 | png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
|
---|
1149 | {
|
---|
1150 | if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
|
---|
1151 | {
|
---|
1152 | /* Everything is invalid */
|
---|
1153 | info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
|
---|
1154 | PNG_INFO_iCCP);
|
---|
1155 |
|
---|
1156 | # ifdef PNG_COLORSPACE_SUPPORTED
|
---|
1157 | /* Clean up the iCCP profile now if it won't be used. */
|
---|
1158 | png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
|
---|
1159 | # else
|
---|
1160 | PNG_UNUSED(png_ptr)
|
---|
1161 | # endif
|
---|
1162 | }
|
---|
1163 |
|
---|
1164 | else
|
---|
1165 | {
|
---|
1166 | # ifdef PNG_COLORSPACE_SUPPORTED
|
---|
1167 | /* Leave the INFO_iCCP flag set if the pngset.c code has already set
|
---|
1168 | * it; this allows a PNG to contain a profile which matches sRGB and
|
---|
1169 | * yet still have that profile retrievable by the application.
|
---|
1170 | */
|
---|
1171 | if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
|
---|
1172 | info_ptr->valid |= PNG_INFO_sRGB;
|
---|
1173 |
|
---|
1174 | else
|
---|
1175 | info_ptr->valid &= ~PNG_INFO_sRGB;
|
---|
1176 |
|
---|
1177 | if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
---|
1178 | info_ptr->valid |= PNG_INFO_cHRM;
|
---|
1179 |
|
---|
1180 | else
|
---|
1181 | info_ptr->valid &= ~PNG_INFO_cHRM;
|
---|
1182 | # endif
|
---|
1183 |
|
---|
1184 | if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
|
---|
1185 | info_ptr->valid |= PNG_INFO_gAMA;
|
---|
1186 |
|
---|
1187 | else
|
---|
1188 | info_ptr->valid &= ~PNG_INFO_gAMA;
|
---|
1189 | }
|
---|
1190 | }
|
---|
1191 |
|
---|
1192 | #ifdef PNG_READ_SUPPORTED
|
---|
1193 | void /* PRIVATE */
|
---|
1194 | png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
|
---|
1195 | {
|
---|
1196 | if (info_ptr == NULL) /* reduce code size; check here not in the caller */
|
---|
1197 | return;
|
---|
1198 |
|
---|
1199 | info_ptr->colorspace = png_ptr->colorspace;
|
---|
1200 | png_colorspace_sync_info(png_ptr, info_ptr);
|
---|
1201 | }
|
---|
1202 | #endif
|
---|
1203 | #endif /* GAMMA */
|
---|
1204 |
|
---|
1205 | #ifdef PNG_COLORSPACE_SUPPORTED
|
---|
1206 | /* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
|
---|
1207 | * cHRM, as opposed to using chromaticities. These internal APIs return
|
---|
1208 | * non-zero on a parameter error. The X, Y and Z values are required to be
|
---|
1209 | * positive and less than 1.0.
|
---|
1210 | */
|
---|
1211 | static int
|
---|
1212 | png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
|
---|
1213 | {
|
---|
1214 | png_int_32 d, dwhite, whiteX, whiteY;
|
---|
1215 |
|
---|
1216 | d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
|
---|
1217 | if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
|
---|
1218 | return 1;
|
---|
1219 | if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
|
---|
1220 | return 1;
|
---|
1221 | dwhite = d;
|
---|
1222 | whiteX = XYZ->red_X;
|
---|
1223 | whiteY = XYZ->red_Y;
|
---|
1224 |
|
---|
1225 | d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
|
---|
1226 | if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
|
---|
1227 | return 1;
|
---|
1228 | if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
|
---|
1229 | return 1;
|
---|
1230 | dwhite += d;
|
---|
1231 | whiteX += XYZ->green_X;
|
---|
1232 | whiteY += XYZ->green_Y;
|
---|
1233 |
|
---|
1234 | d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
|
---|
1235 | if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
|
---|
1236 | return 1;
|
---|
1237 | if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
|
---|
1238 | return 1;
|
---|
1239 | dwhite += d;
|
---|
1240 | whiteX += XYZ->blue_X;
|
---|
1241 | whiteY += XYZ->blue_Y;
|
---|
1242 |
|
---|
1243 | /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
|
---|
1244 | * thus:
|
---|
1245 | */
|
---|
1246 | if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
|
---|
1247 | return 1;
|
---|
1248 | if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
|
---|
1249 | return 1;
|
---|
1250 |
|
---|
1251 | return 0;
|
---|
1252 | }
|
---|
1253 |
|
---|
1254 | static int
|
---|
1255 | png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
|
---|
1256 | {
|
---|
1257 | png_fixed_point red_inverse, green_inverse, blue_scale;
|
---|
1258 | png_fixed_point left, right, denominator;
|
---|
1259 |
|
---|
1260 | /* Check xy and, implicitly, z. Note that wide gamut color spaces typically
|
---|
1261 | * have end points with 0 tristimulus values (these are impossible end
|
---|
1262 | * points, but they are used to cover the possible colors). We check
|
---|
1263 | * xy->whitey against 5, not 0, to avoid a possible integer overflow.
|
---|
1264 | */
|
---|
1265 | if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
|
---|
1266 | if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
|
---|
1267 | if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
|
---|
1268 | if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
|
---|
1269 | if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
|
---|
1270 | if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
|
---|
1271 | if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
|
---|
1272 | if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
|
---|
1273 |
|
---|
1274 | /* The reverse calculation is more difficult because the original tristimulus
|
---|
1275 | * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
|
---|
1276 | * derived values were recorded in the cHRM chunk;
|
---|
1277 | * (red,green,blue,white)x(x,y). This loses one degree of freedom and
|
---|
1278 | * therefore an arbitrary ninth value has to be introduced to undo the
|
---|
1279 | * original transformations.
|
---|
1280 | *
|
---|
1281 | * Think of the original end-points as points in (X,Y,Z) space. The
|
---|
1282 | * chromaticity values (c) have the property:
|
---|
1283 | *
|
---|
1284 | * C
|
---|
1285 | * c = ---------
|
---|
1286 | * X + Y + Z
|
---|
1287 | *
|
---|
1288 | * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
|
---|
1289 | * three chromaticity values (x,y,z) for each end-point obey the
|
---|
1290 | * relationship:
|
---|
1291 | *
|
---|
1292 | * x + y + z = 1
|
---|
1293 | *
|
---|
1294 | * This describes the plane in (X,Y,Z) space that intersects each axis at the
|
---|
1295 | * value 1.0; call this the chromaticity plane. Thus the chromaticity
|
---|
1296 | * calculation has scaled each end-point so that it is on the x+y+z=1 plane
|
---|
1297 | * and chromaticity is the intersection of the vector from the origin to the
|
---|
1298 | * (X,Y,Z) value with the chromaticity plane.
|
---|
1299 | *
|
---|
1300 | * To fully invert the chromaticity calculation we would need the three
|
---|
1301 | * end-point scale factors, (red-scale, green-scale, blue-scale), but these
|
---|
1302 | * were not recorded. Instead we calculated the reference white (X,Y,Z) and
|
---|
1303 | * recorded the chromaticity of this. The reference white (X,Y,Z) would have
|
---|
1304 | * given all three of the scale factors since:
|
---|
1305 | *
|
---|
1306 | * color-C = color-c * color-scale
|
---|
1307 | * white-C = red-C + green-C + blue-C
|
---|
1308 | * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
|
---|
1309 | *
|
---|
1310 | * But cHRM records only white-x and white-y, so we have lost the white scale
|
---|
1311 | * factor:
|
---|
1312 | *
|
---|
1313 | * white-C = white-c*white-scale
|
---|
1314 | *
|
---|
1315 | * To handle this the inverse transformation makes an arbitrary assumption
|
---|
1316 | * about white-scale:
|
---|
1317 | *
|
---|
1318 | * Assume: white-Y = 1.0
|
---|
1319 | * Hence: white-scale = 1/white-y
|
---|
1320 | * Or: red-Y + green-Y + blue-Y = 1.0
|
---|
1321 | *
|
---|
1322 | * Notice the last statement of the assumption gives an equation in three of
|
---|
1323 | * the nine values we want to calculate. 8 more equations come from the
|
---|
1324 | * above routine as summarised at the top above (the chromaticity
|
---|
1325 | * calculation):
|
---|
1326 | *
|
---|
1327 | * Given: color-x = color-X / (color-X + color-Y + color-Z)
|
---|
1328 | * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
|
---|
1329 | *
|
---|
1330 | * This is 9 simultaneous equations in the 9 variables "color-C" and can be
|
---|
1331 | * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
|
---|
1332 | * determinants, however this is not as bad as it seems because only 28 of
|
---|
1333 | * the total of 90 terms in the various matrices are non-zero. Nevertheless
|
---|
1334 | * Cramer's rule is notoriously numerically unstable because the determinant
|
---|
1335 | * calculation involves the difference of large, but similar, numbers. It is
|
---|
1336 | * difficult to be sure that the calculation is stable for real world values
|
---|
1337 | * and it is certain that it becomes unstable where the end points are close
|
---|
1338 | * together.
|
---|
1339 | *
|
---|
1340 | * So this code uses the perhaps slightly less optimal but more
|
---|
1341 | * understandable and totally obvious approach of calculating color-scale.
|
---|
1342 | *
|
---|
1343 | * This algorithm depends on the precision in white-scale and that is
|
---|
1344 | * (1/white-y), so we can immediately see that as white-y approaches 0 the
|
---|
1345 | * accuracy inherent in the cHRM chunk drops off substantially.
|
---|
1346 | *
|
---|
1347 | * libpng arithmetic: a simple inversion of the above equations
|
---|
1348 | * ------------------------------------------------------------
|
---|
1349 | *
|
---|
1350 | * white_scale = 1/white-y
|
---|
1351 | * white-X = white-x * white-scale
|
---|
1352 | * white-Y = 1.0
|
---|
1353 | * white-Z = (1 - white-x - white-y) * white_scale
|
---|
1354 | *
|
---|
1355 | * white-C = red-C + green-C + blue-C
|
---|
1356 | * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
|
---|
1357 | *
|
---|
1358 | * This gives us three equations in (red-scale,green-scale,blue-scale) where
|
---|
1359 | * all the coefficients are now known:
|
---|
1360 | *
|
---|
1361 | * red-x*red-scale + green-x*green-scale + blue-x*blue-scale
|
---|
1362 | * = white-x/white-y
|
---|
1363 | * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
|
---|
1364 | * red-z*red-scale + green-z*green-scale + blue-z*blue-scale
|
---|
1365 | * = (1 - white-x - white-y)/white-y
|
---|
1366 | *
|
---|
1367 | * In the last equation color-z is (1 - color-x - color-y) so we can add all
|
---|
1368 | * three equations together to get an alternative third:
|
---|
1369 | *
|
---|
1370 | * red-scale + green-scale + blue-scale = 1/white-y = white-scale
|
---|
1371 | *
|
---|
1372 | * So now we have a Cramer's rule solution where the determinants are just
|
---|
1373 | * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
|
---|
1374 | * multiplication of three coefficients so we can't guarantee to avoid
|
---|
1375 | * overflow in the libpng fixed point representation. Using Cramer's rule in
|
---|
1376 | * floating point is probably a good choice here, but it's not an option for
|
---|
1377 | * fixed point. Instead proceed to simplify the first two equations by
|
---|
1378 | * eliminating what is likely to be the largest value, blue-scale:
|
---|
1379 | *
|
---|
1380 | * blue-scale = white-scale - red-scale - green-scale
|
---|
1381 | *
|
---|
1382 | * Hence:
|
---|
1383 | *
|
---|
1384 | * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
|
---|
1385 | * (white-x - blue-x)*white-scale
|
---|
1386 | *
|
---|
1387 | * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
|
---|
1388 | * 1 - blue-y*white-scale
|
---|
1389 | *
|
---|
1390 | * And now we can trivially solve for (red-scale,green-scale):
|
---|
1391 | *
|
---|
1392 | * green-scale =
|
---|
1393 | * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
|
---|
1394 | * -----------------------------------------------------------
|
---|
1395 | * green-x - blue-x
|
---|
1396 | *
|
---|
1397 | * red-scale =
|
---|
1398 | * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
|
---|
1399 | * ---------------------------------------------------------
|
---|
1400 | * red-y - blue-y
|
---|
1401 | *
|
---|
1402 | * Hence:
|
---|
1403 | *
|
---|
1404 | * red-scale =
|
---|
1405 | * ( (green-x - blue-x) * (white-y - blue-y) -
|
---|
1406 | * (green-y - blue-y) * (white-x - blue-x) ) / white-y
|
---|
1407 | * -------------------------------------------------------------------------
|
---|
1408 | * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
|
---|
1409 | *
|
---|
1410 | * green-scale =
|
---|
1411 | * ( (red-y - blue-y) * (white-x - blue-x) -
|
---|
1412 | * (red-x - blue-x) * (white-y - blue-y) ) / white-y
|
---|
1413 | * -------------------------------------------------------------------------
|
---|
1414 | * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
|
---|
1415 | *
|
---|
1416 | * Accuracy:
|
---|
1417 | * The input values have 5 decimal digits of accuracy. The values are all in
|
---|
1418 | * the range 0 < value < 1, so simple products are in the same range but may
|
---|
1419 | * need up to 10 decimal digits to preserve the original precision and avoid
|
---|
1420 | * underflow. Because we are using a 32-bit signed representation we cannot
|
---|
1421 | * match this; the best is a little over 9 decimal digits, less than 10.
|
---|
1422 | *
|
---|
1423 | * The approach used here is to preserve the maximum precision within the
|
---|
1424 | * signed representation. Because the red-scale calculation above uses the
|
---|
1425 | * difference between two products of values that must be in the range -1..+1
|
---|
1426 | * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
|
---|
1427 | * factor is irrelevant in the calculation because it is applied to both
|
---|
1428 | * numerator and denominator.
|
---|
1429 | *
|
---|
1430 | * Note that the values of the differences of the products of the
|
---|
1431 | * chromaticities in the above equations tend to be small, for example for
|
---|
1432 | * the sRGB chromaticities they are:
|
---|
1433 | *
|
---|
1434 | * red numerator: -0.04751
|
---|
1435 | * green numerator: -0.08788
|
---|
1436 | * denominator: -0.2241 (without white-y multiplication)
|
---|
1437 | *
|
---|
1438 | * The resultant Y coefficients from the chromaticities of some widely used
|
---|
1439 | * color space definitions are (to 15 decimal places):
|
---|
1440 | *
|
---|
1441 | * sRGB
|
---|
1442 | * 0.212639005871510 0.715168678767756 0.072192315360734
|
---|
1443 | * Kodak ProPhoto
|
---|
1444 | * 0.288071128229293 0.711843217810102 0.000085653960605
|
---|
1445 | * Adobe RGB
|
---|
1446 | * 0.297344975250536 0.627363566255466 0.075291458493998
|
---|
1447 | * Adobe Wide Gamut RGB
|
---|
1448 | * 0.258728243040113 0.724682314948566 0.016589442011321
|
---|
1449 | */
|
---|
1450 | /* By the argument, above overflow should be impossible here. The return
|
---|
1451 | * value of 2 indicates an internal error to the caller.
|
---|
1452 | */
|
---|
1453 | if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
|
---|
1454 | return 2;
|
---|
1455 | if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
|
---|
1456 | return 2;
|
---|
1457 | denominator = left - right;
|
---|
1458 |
|
---|
1459 | /* Now find the red numerator. */
|
---|
1460 | if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
|
---|
1461 | return 2;
|
---|
1462 | if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
|
---|
1463 | return 2;
|
---|
1464 |
|
---|
1465 | /* Overflow is possible here and it indicates an extreme set of PNG cHRM
|
---|
1466 | * chunk values. This calculation actually returns the reciprocal of the
|
---|
1467 | * scale value because this allows us to delay the multiplication of white-y
|
---|
1468 | * into the denominator, which tends to produce a small number.
|
---|
1469 | */
|
---|
1470 | if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
|
---|
1471 | red_inverse <= xy->whitey /* r+g+b scales = white scale */)
|
---|
1472 | return 1;
|
---|
1473 |
|
---|
1474 | /* Similarly for green_inverse: */
|
---|
1475 | if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
|
---|
1476 | return 2;
|
---|
1477 | if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
|
---|
1478 | return 2;
|
---|
1479 | if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
|
---|
1480 | green_inverse <= xy->whitey)
|
---|
1481 | return 1;
|
---|
1482 |
|
---|
1483 | /* And the blue scale, the checks above guarantee this can't overflow but it
|
---|
1484 | * can still produce 0 for extreme cHRM values.
|
---|
1485 | */
|
---|
1486 | blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
|
---|
1487 | png_reciprocal(green_inverse);
|
---|
1488 | if (blue_scale <= 0)
|
---|
1489 | return 1;
|
---|
1490 |
|
---|
1491 |
|
---|
1492 | /* And fill in the png_XYZ: */
|
---|
1493 | if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
|
---|
1494 | return 1;
|
---|
1495 | if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
|
---|
1496 | return 1;
|
---|
1497 | if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
|
---|
1498 | red_inverse) == 0)
|
---|
1499 | return 1;
|
---|
1500 |
|
---|
1501 | if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
|
---|
1502 | return 1;
|
---|
1503 | if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
|
---|
1504 | return 1;
|
---|
1505 | if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
|
---|
1506 | green_inverse) == 0)
|
---|
1507 | return 1;
|
---|
1508 |
|
---|
1509 | if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
|
---|
1510 | return 1;
|
---|
1511 | if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
|
---|
1512 | return 1;
|
---|
1513 | if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
|
---|
1514 | PNG_FP_1) == 0)
|
---|
1515 | return 1;
|
---|
1516 |
|
---|
1517 | return 0; /*success*/
|
---|
1518 | }
|
---|
1519 |
|
---|
1520 | static int
|
---|
1521 | png_XYZ_normalize(png_XYZ *XYZ)
|
---|
1522 | {
|
---|
1523 | png_int_32 Y;
|
---|
1524 |
|
---|
1525 | if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
|
---|
1526 | XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
|
---|
1527 | XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
|
---|
1528 | return 1;
|
---|
1529 |
|
---|
1530 | /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
|
---|
1531 | * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
|
---|
1532 | * relying on addition of two positive values producing a negative one is not
|
---|
1533 | * safe.
|
---|
1534 | */
|
---|
1535 | Y = XYZ->red_Y;
|
---|
1536 | if (0x7fffffff - Y < XYZ->green_X)
|
---|
1537 | return 1;
|
---|
1538 | Y += XYZ->green_Y;
|
---|
1539 | if (0x7fffffff - Y < XYZ->blue_X)
|
---|
1540 | return 1;
|
---|
1541 | Y += XYZ->blue_Y;
|
---|
1542 |
|
---|
1543 | if (Y != PNG_FP_1)
|
---|
1544 | {
|
---|
1545 | if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
|
---|
1546 | return 1;
|
---|
1547 | if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
|
---|
1548 | return 1;
|
---|
1549 | if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
|
---|
1550 | return 1;
|
---|
1551 |
|
---|
1552 | if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
|
---|
1553 | return 1;
|
---|
1554 | if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
|
---|
1555 | return 1;
|
---|
1556 | if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
|
---|
1557 | return 1;
|
---|
1558 |
|
---|
1559 | if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
|
---|
1560 | return 1;
|
---|
1561 | if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
|
---|
1562 | return 1;
|
---|
1563 | if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
|
---|
1564 | return 1;
|
---|
1565 | }
|
---|
1566 |
|
---|
1567 | return 0;
|
---|
1568 | }
|
---|
1569 |
|
---|
1570 | static int
|
---|
1571 | png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
|
---|
1572 | {
|
---|
1573 | /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
|
---|
1574 | if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
|
---|
1575 | PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
|
---|
1576 | PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
|
---|
1577 | PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
|
---|
1578 | PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
|
---|
1579 | PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
|
---|
1580 | PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
|
---|
1581 | PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
|
---|
1582 | return 0;
|
---|
1583 | return 1;
|
---|
1584 | }
|
---|
1585 |
|
---|
1586 | /* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
|
---|
1587 | * chunk chromaticities. Earlier checks used to simply look for the overflow
|
---|
1588 | * condition (where the determinant of the matrix to solve for XYZ ends up zero
|
---|
1589 | * because the chromaticity values are not all distinct.) Despite this it is
|
---|
1590 | * theoretically possible to produce chromaticities that are apparently valid
|
---|
1591 | * but that rapidly degrade to invalid, potentially crashing, sets because of
|
---|
1592 | * arithmetic inaccuracies when calculations are performed on them. The new
|
---|
1593 | * check is to round-trip xy -> XYZ -> xy and then check that the result is
|
---|
1594 | * within a small percentage of the original.
|
---|
1595 | */
|
---|
1596 | static int
|
---|
1597 | png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
|
---|
1598 | {
|
---|
1599 | int result;
|
---|
1600 | png_xy xy_test;
|
---|
1601 |
|
---|
1602 | /* As a side-effect this routine also returns the XYZ endpoints. */
|
---|
1603 | result = png_XYZ_from_xy(XYZ, xy);
|
---|
1604 | if (result != 0)
|
---|
1605 | return result;
|
---|
1606 |
|
---|
1607 | result = png_xy_from_XYZ(&xy_test, XYZ);
|
---|
1608 | if (result != 0)
|
---|
1609 | return result;
|
---|
1610 |
|
---|
1611 | if (png_colorspace_endpoints_match(xy, &xy_test,
|
---|
1612 | 5/*actually, the math is pretty accurate*/) != 0)
|
---|
1613 | return 0;
|
---|
1614 |
|
---|
1615 | /* Too much slip */
|
---|
1616 | return 1;
|
---|
1617 | }
|
---|
1618 |
|
---|
1619 | /* This is the check going the other way. The XYZ is modified to normalize it
|
---|
1620 | * (another side-effect) and the xy chromaticities are returned.
|
---|
1621 | */
|
---|
1622 | static int
|
---|
1623 | png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
|
---|
1624 | {
|
---|
1625 | int result;
|
---|
1626 | png_XYZ XYZtemp;
|
---|
1627 |
|
---|
1628 | result = png_XYZ_normalize(XYZ);
|
---|
1629 | if (result != 0)
|
---|
1630 | return result;
|
---|
1631 |
|
---|
1632 | result = png_xy_from_XYZ(xy, XYZ);
|
---|
1633 | if (result != 0)
|
---|
1634 | return result;
|
---|
1635 |
|
---|
1636 | XYZtemp = *XYZ;
|
---|
1637 | return png_colorspace_check_xy(&XYZtemp, xy);
|
---|
1638 | }
|
---|
1639 |
|
---|
1640 | /* Used to check for an endpoint match against sRGB */
|
---|
1641 | static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
|
---|
1642 | {
|
---|
1643 | /* color x y */
|
---|
1644 | /* red */ 64000, 33000,
|
---|
1645 | /* green */ 30000, 60000,
|
---|
1646 | /* blue */ 15000, 6000,
|
---|
1647 | /* white */ 31270, 32900
|
---|
1648 | };
|
---|
1649 |
|
---|
1650 | static int
|
---|
1651 | png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
|
---|
1652 | png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
|
---|
1653 | int preferred)
|
---|
1654 | {
|
---|
1655 | if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
---|
1656 | return 0;
|
---|
1657 |
|
---|
1658 | /* The consistency check is performed on the chromaticities; this factors out
|
---|
1659 | * variations because of the normalization (or not) of the end point Y
|
---|
1660 | * values.
|
---|
1661 | */
|
---|
1662 | if (preferred < 2 &&
|
---|
1663 | (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
---|
1664 | {
|
---|
1665 | /* The end points must be reasonably close to any we already have. The
|
---|
1666 | * following allows an error of up to +/-.001
|
---|
1667 | */
|
---|
1668 | if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
|
---|
1669 | 100) == 0)
|
---|
1670 | {
|
---|
1671 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1672 | png_benign_error(png_ptr, "inconsistent chromaticities");
|
---|
1673 | return 0; /* failed */
|
---|
1674 | }
|
---|
1675 |
|
---|
1676 | /* Only overwrite with preferred values */
|
---|
1677 | if (preferred == 0)
|
---|
1678 | return 1; /* ok, but no change */
|
---|
1679 | }
|
---|
1680 |
|
---|
1681 | colorspace->end_points_xy = *xy;
|
---|
1682 | colorspace->end_points_XYZ = *XYZ;
|
---|
1683 | colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
|
---|
1684 |
|
---|
1685 | /* The end points are normally quoted to two decimal digits, so allow +/-0.01
|
---|
1686 | * on this test.
|
---|
1687 | */
|
---|
1688 | if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
|
---|
1689 | colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
|
---|
1690 |
|
---|
1691 | else
|
---|
1692 | colorspace->flags &= PNG_COLORSPACE_CANCEL(
|
---|
1693 | PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
|
---|
1694 |
|
---|
1695 | return 2; /* ok and changed */
|
---|
1696 | }
|
---|
1697 |
|
---|
1698 | int /* PRIVATE */
|
---|
1699 | png_colorspace_set_chromaticities(png_const_structrp png_ptr,
|
---|
1700 | png_colorspacerp colorspace, const png_xy *xy, int preferred)
|
---|
1701 | {
|
---|
1702 | /* We must check the end points to ensure they are reasonable - in the past
|
---|
1703 | * color management systems have crashed as a result of getting bogus
|
---|
1704 | * colorant values, while this isn't the fault of libpng it is the
|
---|
1705 | * responsibility of libpng because PNG carries the bomb and libpng is in a
|
---|
1706 | * position to protect against it.
|
---|
1707 | */
|
---|
1708 | png_XYZ XYZ;
|
---|
1709 |
|
---|
1710 | switch (png_colorspace_check_xy(&XYZ, xy))
|
---|
1711 | {
|
---|
1712 | case 0: /* success */
|
---|
1713 | return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
|
---|
1714 | preferred);
|
---|
1715 |
|
---|
1716 | case 1:
|
---|
1717 | /* We can't invert the chromaticities so we can't produce value XYZ
|
---|
1718 | * values. Likely as not a color management system will fail too.
|
---|
1719 | */
|
---|
1720 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1721 | png_benign_error(png_ptr, "invalid chromaticities");
|
---|
1722 | break;
|
---|
1723 |
|
---|
1724 | default:
|
---|
1725 | /* libpng is broken; this should be a warning but if it happens we
|
---|
1726 | * want error reports so for the moment it is an error.
|
---|
1727 | */
|
---|
1728 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1729 | png_error(png_ptr, "internal error checking chromaticities");
|
---|
1730 | }
|
---|
1731 |
|
---|
1732 | return 0; /* failed */
|
---|
1733 | }
|
---|
1734 |
|
---|
1735 | int /* PRIVATE */
|
---|
1736 | png_colorspace_set_endpoints(png_const_structrp png_ptr,
|
---|
1737 | png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
|
---|
1738 | {
|
---|
1739 | png_XYZ XYZ = *XYZ_in;
|
---|
1740 | png_xy xy;
|
---|
1741 |
|
---|
1742 | switch (png_colorspace_check_XYZ(&xy, &XYZ))
|
---|
1743 | {
|
---|
1744 | case 0:
|
---|
1745 | return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
|
---|
1746 | preferred);
|
---|
1747 |
|
---|
1748 | case 1:
|
---|
1749 | /* End points are invalid. */
|
---|
1750 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1751 | png_benign_error(png_ptr, "invalid end points");
|
---|
1752 | break;
|
---|
1753 |
|
---|
1754 | default:
|
---|
1755 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1756 | png_error(png_ptr, "internal error checking chromaticities");
|
---|
1757 | }
|
---|
1758 |
|
---|
1759 | return 0; /* failed */
|
---|
1760 | }
|
---|
1761 |
|
---|
1762 | #if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
|
---|
1763 | /* Error message generation */
|
---|
1764 | static char
|
---|
1765 | png_icc_tag_char(png_uint_32 byte)
|
---|
1766 | {
|
---|
1767 | byte &= 0xff;
|
---|
1768 | if (byte >= 32 && byte <= 126)
|
---|
1769 | return (char)byte;
|
---|
1770 | else
|
---|
1771 | return '?';
|
---|
1772 | }
|
---|
1773 |
|
---|
1774 | static void
|
---|
1775 | png_icc_tag_name(char *name, png_uint_32 tag)
|
---|
1776 | {
|
---|
1777 | name[0] = '\'';
|
---|
1778 | name[1] = png_icc_tag_char(tag >> 24);
|
---|
1779 | name[2] = png_icc_tag_char(tag >> 16);
|
---|
1780 | name[3] = png_icc_tag_char(tag >> 8);
|
---|
1781 | name[4] = png_icc_tag_char(tag );
|
---|
1782 | name[5] = '\'';
|
---|
1783 | }
|
---|
1784 |
|
---|
1785 | static int
|
---|
1786 | is_ICC_signature_char(png_alloc_size_t it)
|
---|
1787 | {
|
---|
1788 | return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
|
---|
1789 | (it >= 97 && it <= 122);
|
---|
1790 | }
|
---|
1791 |
|
---|
1792 | static int
|
---|
1793 | is_ICC_signature(png_alloc_size_t it)
|
---|
1794 | {
|
---|
1795 | return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
|
---|
1796 | is_ICC_signature_char((it >> 16) & 0xff) &&
|
---|
1797 | is_ICC_signature_char((it >> 8) & 0xff) &&
|
---|
1798 | is_ICC_signature_char(it & 0xff);
|
---|
1799 | }
|
---|
1800 |
|
---|
1801 | static int
|
---|
1802 | png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
1803 | png_const_charp name, png_alloc_size_t value, png_const_charp reason)
|
---|
1804 | {
|
---|
1805 | size_t pos;
|
---|
1806 | char message[196]; /* see below for calculation */
|
---|
1807 |
|
---|
1808 | if (colorspace != NULL)
|
---|
1809 | colorspace->flags |= PNG_COLORSPACE_INVALID;
|
---|
1810 |
|
---|
1811 | pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
|
---|
1812 | pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
|
---|
1813 | pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
|
---|
1814 | if (is_ICC_signature(value) != 0)
|
---|
1815 | {
|
---|
1816 | /* So 'value' is at most 4 bytes and the following cast is safe */
|
---|
1817 | png_icc_tag_name(message+pos, (png_uint_32)value);
|
---|
1818 | pos += 6; /* total +8; less than the else clause */
|
---|
1819 | message[pos++] = ':';
|
---|
1820 | message[pos++] = ' ';
|
---|
1821 | }
|
---|
1822 | # ifdef PNG_WARNINGS_SUPPORTED
|
---|
1823 | else
|
---|
1824 | {
|
---|
1825 | char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114 */
|
---|
1826 |
|
---|
1827 | pos = png_safecat(message, (sizeof message), pos,
|
---|
1828 | png_format_number(number, number+(sizeof number),
|
---|
1829 | PNG_NUMBER_FORMAT_x, value));
|
---|
1830 | pos = png_safecat(message, (sizeof message), pos, "h: "); /* +2 = 116 */
|
---|
1831 | }
|
---|
1832 | # endif
|
---|
1833 | /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
|
---|
1834 | pos = png_safecat(message, (sizeof message), pos, reason);
|
---|
1835 | PNG_UNUSED(pos)
|
---|
1836 |
|
---|
1837 | /* This is recoverable, but make it unconditionally an app_error on write to
|
---|
1838 | * avoid writing invalid ICC profiles into PNG files (i.e., we handle them
|
---|
1839 | * on read, with a warning, but on write unless the app turns off
|
---|
1840 | * application errors the PNG won't be written.)
|
---|
1841 | */
|
---|
1842 | png_chunk_report(png_ptr, message,
|
---|
1843 | (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
|
---|
1844 |
|
---|
1845 | return 0;
|
---|
1846 | }
|
---|
1847 | #endif /* sRGB || iCCP */
|
---|
1848 |
|
---|
1849 | #ifdef PNG_sRGB_SUPPORTED
|
---|
1850 | int /* PRIVATE */
|
---|
1851 | png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
1852 | int intent)
|
---|
1853 | {
|
---|
1854 | /* sRGB sets known gamma, end points and (from the chunk) intent. */
|
---|
1855 | /* IMPORTANT: these are not necessarily the values found in an ICC profile
|
---|
1856 | * because ICC profiles store values adapted to a D50 environment; it is
|
---|
1857 | * expected that the ICC profile mediaWhitePointTag will be D50; see the
|
---|
1858 | * checks and code elsewhere to understand this better.
|
---|
1859 | *
|
---|
1860 | * These XYZ values, which are accurate to 5dp, produce rgb to gray
|
---|
1861 | * coefficients of (6968,23435,2366), which are reduced (because they add up
|
---|
1862 | * to 32769 not 32768) to (6968,23434,2366). These are the values that
|
---|
1863 | * libpng has traditionally used (and are the best values given the 15bit
|
---|
1864 | * algorithm used by the rgb to gray code.)
|
---|
1865 | */
|
---|
1866 | static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
|
---|
1867 | {
|
---|
1868 | /* color X Y Z */
|
---|
1869 | /* red */ 41239, 21264, 1933,
|
---|
1870 | /* green */ 35758, 71517, 11919,
|
---|
1871 | /* blue */ 18048, 7219, 95053
|
---|
1872 | };
|
---|
1873 |
|
---|
1874 | /* Do nothing if the colorspace is already invalidated. */
|
---|
1875 | if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
---|
1876 | return 0;
|
---|
1877 |
|
---|
1878 | /* Check the intent, then check for existing settings. It is valid for the
|
---|
1879 | * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
|
---|
1880 | * be consistent with the correct values. If, however, this function is
|
---|
1881 | * called below because an iCCP chunk matches sRGB then it is quite
|
---|
1882 | * conceivable that an older app recorded incorrect gAMA and cHRM because of
|
---|
1883 | * an incorrect calculation based on the values in the profile - this does
|
---|
1884 | * *not* invalidate the profile (though it still produces an error, which can
|
---|
1885 | * be ignored.)
|
---|
1886 | */
|
---|
1887 | if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
|
---|
1888 | return png_icc_profile_error(png_ptr, colorspace, "sRGB",
|
---|
1889 | (png_alloc_size_t)intent, "invalid sRGB rendering intent");
|
---|
1890 |
|
---|
1891 | if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
|
---|
1892 | colorspace->rendering_intent != intent)
|
---|
1893 | return png_icc_profile_error(png_ptr, colorspace, "sRGB",
|
---|
1894 | (png_alloc_size_t)intent, "inconsistent rendering intents");
|
---|
1895 |
|
---|
1896 | if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
|
---|
1897 | {
|
---|
1898 | png_benign_error(png_ptr, "duplicate sRGB information ignored");
|
---|
1899 | return 0;
|
---|
1900 | }
|
---|
1901 |
|
---|
1902 | /* If the standard sRGB cHRM chunk does not match the one from the PNG file
|
---|
1903 | * warn but overwrite the value with the correct one.
|
---|
1904 | */
|
---|
1905 | if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
|
---|
1906 | !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
|
---|
1907 | 100))
|
---|
1908 | png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
|
---|
1909 | PNG_CHUNK_ERROR);
|
---|
1910 |
|
---|
1911 | /* This check is just done for the error reporting - the routine always
|
---|
1912 | * returns true when the 'from' argument corresponds to sRGB (2).
|
---|
1913 | */
|
---|
1914 | (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
|
---|
1915 | 2/*from sRGB*/);
|
---|
1916 |
|
---|
1917 | /* intent: bugs in GCC force 'int' to be used as the parameter type. */
|
---|
1918 | colorspace->rendering_intent = (png_uint_16)intent;
|
---|
1919 | colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
|
---|
1920 |
|
---|
1921 | /* endpoints */
|
---|
1922 | colorspace->end_points_xy = sRGB_xy;
|
---|
1923 | colorspace->end_points_XYZ = sRGB_XYZ;
|
---|
1924 | colorspace->flags |=
|
---|
1925 | (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
|
---|
1926 |
|
---|
1927 | /* gamma */
|
---|
1928 | colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
|
---|
1929 | colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
|
---|
1930 |
|
---|
1931 | /* Finally record that we have an sRGB profile */
|
---|
1932 | colorspace->flags |=
|
---|
1933 | (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
|
---|
1934 |
|
---|
1935 | return 1; /* set */
|
---|
1936 | }
|
---|
1937 | #endif /* sRGB */
|
---|
1938 |
|
---|
1939 | #ifdef PNG_iCCP_SUPPORTED
|
---|
1940 | /* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
|
---|
1941 | * is XYZ(0.9642,1.0,0.8249), which scales to:
|
---|
1942 | *
|
---|
1943 | * (63189.8112, 65536, 54060.6464)
|
---|
1944 | */
|
---|
1945 | static const png_byte D50_nCIEXYZ[12] =
|
---|
1946 | { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
|
---|
1947 |
|
---|
1948 | static int /* bool */
|
---|
1949 | icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
1950 | png_const_charp name, png_uint_32 profile_length)
|
---|
1951 | {
|
---|
1952 | if (profile_length < 132)
|
---|
1953 | return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
---|
1954 | "too short");
|
---|
1955 | return 1;
|
---|
1956 | }
|
---|
1957 |
|
---|
1958 | #ifdef PNG_READ_iCCP_SUPPORTED
|
---|
1959 | int /* PRIVATE */
|
---|
1960 | png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
1961 | png_const_charp name, png_uint_32 profile_length)
|
---|
1962 | {
|
---|
1963 | if (!icc_check_length(png_ptr, colorspace, name, profile_length))
|
---|
1964 | return 0;
|
---|
1965 |
|
---|
1966 | /* This needs to be here because the 'normal' check is in
|
---|
1967 | * png_decompress_chunk, yet this happens after the attempt to
|
---|
1968 | * png_malloc_base the required data. We only need this on read; on write
|
---|
1969 | * the caller supplies the profile buffer so libpng doesn't allocate it. See
|
---|
1970 | * the call to icc_check_length below (the write case).
|
---|
1971 | */
|
---|
1972 | # ifdef PNG_SET_USER_LIMITS_SUPPORTED
|
---|
1973 | else if (png_ptr->user_chunk_malloc_max > 0 &&
|
---|
1974 | png_ptr->user_chunk_malloc_max < profile_length)
|
---|
1975 | return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
---|
1976 | "exceeds application limits");
|
---|
1977 | # elif PNG_USER_CHUNK_MALLOC_MAX > 0
|
---|
1978 | else if (PNG_USER_CHUNK_MALLOC_MAX < profile_length)
|
---|
1979 | return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
---|
1980 | "exceeds libpng limits");
|
---|
1981 | # else /* !SET_USER_LIMITS */
|
---|
1982 | /* This will get compiled out on all 32-bit and better systems. */
|
---|
1983 | else if (PNG_SIZE_MAX < profile_length)
|
---|
1984 | return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
---|
1985 | "exceeds system limits");
|
---|
1986 | # endif /* !SET_USER_LIMITS */
|
---|
1987 |
|
---|
1988 | return 1;
|
---|
1989 | }
|
---|
1990 | #endif /* READ_iCCP */
|
---|
1991 |
|
---|
1992 | int /* PRIVATE */
|
---|
1993 | png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
1994 | png_const_charp name, png_uint_32 profile_length,
|
---|
1995 | png_const_bytep profile/* first 132 bytes only */, int color_type)
|
---|
1996 | {
|
---|
1997 | png_uint_32 temp;
|
---|
1998 |
|
---|
1999 | /* Length check; this cannot be ignored in this code because profile_length
|
---|
2000 | * is used later to check the tag table, so even if the profile seems over
|
---|
2001 | * long profile_length from the caller must be correct. The caller can fix
|
---|
2002 | * this up on read or write by just passing in the profile header length.
|
---|
2003 | */
|
---|
2004 | temp = png_get_uint_32(profile);
|
---|
2005 | if (temp != profile_length)
|
---|
2006 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2007 | "length does not match profile");
|
---|
2008 |
|
---|
2009 | temp = (png_uint_32) (*(profile+8));
|
---|
2010 | if (temp > 3 && (profile_length & 3))
|
---|
2011 | return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
---|
2012 | "invalid length");
|
---|
2013 |
|
---|
2014 | temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
|
---|
2015 | if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
|
---|
2016 | profile_length < 132+12*temp) /* truncated tag table */
|
---|
2017 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2018 | "tag count too large");
|
---|
2019 |
|
---|
2020 | /* The 'intent' must be valid or we can't store it, ICC limits the intent to
|
---|
2021 | * 16 bits.
|
---|
2022 | */
|
---|
2023 | temp = png_get_uint_32(profile+64);
|
---|
2024 | if (temp >= 0xffff) /* The ICC limit */
|
---|
2025 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2026 | "invalid rendering intent");
|
---|
2027 |
|
---|
2028 | /* This is just a warning because the profile may be valid in future
|
---|
2029 | * versions.
|
---|
2030 | */
|
---|
2031 | if (temp >= PNG_sRGB_INTENT_LAST)
|
---|
2032 | (void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
---|
2033 | "intent outside defined range");
|
---|
2034 |
|
---|
2035 | /* At this point the tag table can't be checked because it hasn't necessarily
|
---|
2036 | * been loaded; however, various header fields can be checked. These checks
|
---|
2037 | * are for values permitted by the PNG spec in an ICC profile; the PNG spec
|
---|
2038 | * restricts the profiles that can be passed in an iCCP chunk (they must be
|
---|
2039 | * appropriate to processing PNG data!)
|
---|
2040 | */
|
---|
2041 |
|
---|
2042 | /* Data checks (could be skipped). These checks must be independent of the
|
---|
2043 | * version number; however, the version number doesn't accommodate changes in
|
---|
2044 | * the header fields (just the known tags and the interpretation of the
|
---|
2045 | * data.)
|
---|
2046 | */
|
---|
2047 | temp = png_get_uint_32(profile+36); /* signature 'ascp' */
|
---|
2048 | if (temp != 0x61637370)
|
---|
2049 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2050 | "invalid signature");
|
---|
2051 |
|
---|
2052 | /* Currently the PCS illuminant/adopted white point (the computational
|
---|
2053 | * white point) are required to be D50,
|
---|
2054 | * however the profile contains a record of the illuminant so perhaps ICC
|
---|
2055 | * expects to be able to change this in the future (despite the rationale in
|
---|
2056 | * the introduction for using a fixed PCS adopted white.) Consequently the
|
---|
2057 | * following is just a warning.
|
---|
2058 | */
|
---|
2059 | if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
|
---|
2060 | (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
|
---|
2061 | "PCS illuminant is not D50");
|
---|
2062 |
|
---|
2063 | /* The PNG spec requires this:
|
---|
2064 | * "If the iCCP chunk is present, the image samples conform to the colour
|
---|
2065 | * space represented by the embedded ICC profile as defined by the
|
---|
2066 | * International Color Consortium [ICC]. The colour space of the ICC profile
|
---|
2067 | * shall be an RGB colour space for colour images (PNG colour types 2, 3, and
|
---|
2068 | * 6), or a greyscale colour space for greyscale images (PNG colour types 0
|
---|
2069 | * and 4)."
|
---|
2070 | *
|
---|
2071 | * This checking code ensures the embedded profile (on either read or write)
|
---|
2072 | * conforms to the specification requirements. Notice that an ICC 'gray'
|
---|
2073 | * color-space profile contains the information to transform the monochrome
|
---|
2074 | * data to XYZ or L*a*b (according to which PCS the profile uses) and this
|
---|
2075 | * should be used in preference to the standard libpng K channel replication
|
---|
2076 | * into R, G and B channels.
|
---|
2077 | *
|
---|
2078 | * Previously it was suggested that an RGB profile on grayscale data could be
|
---|
2079 | * handled. However it it is clear that using an RGB profile in this context
|
---|
2080 | * must be an error - there is no specification of what it means. Thus it is
|
---|
2081 | * almost certainly more correct to ignore the profile.
|
---|
2082 | */
|
---|
2083 | temp = png_get_uint_32(profile+16); /* data colour space field */
|
---|
2084 | switch (temp)
|
---|
2085 | {
|
---|
2086 | case 0x52474220: /* 'RGB ' */
|
---|
2087 | if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
|
---|
2088 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2089 | "RGB color space not permitted on grayscale PNG");
|
---|
2090 | break;
|
---|
2091 |
|
---|
2092 | case 0x47524159: /* 'GRAY' */
|
---|
2093 | if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
|
---|
2094 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2095 | "Gray color space not permitted on RGB PNG");
|
---|
2096 | break;
|
---|
2097 |
|
---|
2098 | default:
|
---|
2099 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2100 | "invalid ICC profile color space");
|
---|
2101 | }
|
---|
2102 |
|
---|
2103 | /* It is up to the application to check that the profile class matches the
|
---|
2104 | * application requirements; the spec provides no guidance, but it's pretty
|
---|
2105 | * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
|
---|
2106 | * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
|
---|
2107 | * cases. Issue an error for device link or abstract profiles - these don't
|
---|
2108 | * contain the records necessary to transform the color-space to anything
|
---|
2109 | * other than the target device (and not even that for an abstract profile).
|
---|
2110 | * Profiles of these classes may not be embedded in images.
|
---|
2111 | */
|
---|
2112 | temp = png_get_uint_32(profile+12); /* profile/device class */
|
---|
2113 | switch (temp)
|
---|
2114 | {
|
---|
2115 | case 0x73636e72: /* 'scnr' */
|
---|
2116 | case 0x6d6e7472: /* 'mntr' */
|
---|
2117 | case 0x70727472: /* 'prtr' */
|
---|
2118 | case 0x73706163: /* 'spac' */
|
---|
2119 | /* All supported */
|
---|
2120 | break;
|
---|
2121 |
|
---|
2122 | case 0x61627374: /* 'abst' */
|
---|
2123 | /* May not be embedded in an image */
|
---|
2124 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2125 | "invalid embedded Abstract ICC profile");
|
---|
2126 |
|
---|
2127 | case 0x6c696e6b: /* 'link' */
|
---|
2128 | /* DeviceLink profiles cannot be interpreted in a non-device specific
|
---|
2129 | * fashion, if an app uses the AToB0Tag in the profile the results are
|
---|
2130 | * undefined unless the result is sent to the intended device,
|
---|
2131 | * therefore a DeviceLink profile should not be found embedded in a
|
---|
2132 | * PNG.
|
---|
2133 | */
|
---|
2134 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2135 | "unexpected DeviceLink ICC profile class");
|
---|
2136 |
|
---|
2137 | case 0x6e6d636c: /* 'nmcl' */
|
---|
2138 | /* A NamedColor profile is also device specific, however it doesn't
|
---|
2139 | * contain an AToB0 tag that is open to misinterpretation. Almost
|
---|
2140 | * certainly it will fail the tests below.
|
---|
2141 | */
|
---|
2142 | (void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
---|
2143 | "unexpected NamedColor ICC profile class");
|
---|
2144 | break;
|
---|
2145 |
|
---|
2146 | default:
|
---|
2147 | /* To allow for future enhancements to the profile accept unrecognized
|
---|
2148 | * profile classes with a warning, these then hit the test below on the
|
---|
2149 | * tag content to ensure they are backward compatible with one of the
|
---|
2150 | * understood profiles.
|
---|
2151 | */
|
---|
2152 | (void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
---|
2153 | "unrecognized ICC profile class");
|
---|
2154 | break;
|
---|
2155 | }
|
---|
2156 |
|
---|
2157 | /* For any profile other than a device link one the PCS must be encoded
|
---|
2158 | * either in XYZ or Lab.
|
---|
2159 | */
|
---|
2160 | temp = png_get_uint_32(profile+20);
|
---|
2161 | switch (temp)
|
---|
2162 | {
|
---|
2163 | case 0x58595a20: /* 'XYZ ' */
|
---|
2164 | case 0x4c616220: /* 'Lab ' */
|
---|
2165 | break;
|
---|
2166 |
|
---|
2167 | default:
|
---|
2168 | return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
---|
2169 | "unexpected ICC PCS encoding");
|
---|
2170 | }
|
---|
2171 |
|
---|
2172 | return 1;
|
---|
2173 | }
|
---|
2174 |
|
---|
2175 | int /* PRIVATE */
|
---|
2176 | png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
2177 | png_const_charp name, png_uint_32 profile_length,
|
---|
2178 | png_const_bytep profile /* header plus whole tag table */)
|
---|
2179 | {
|
---|
2180 | png_uint_32 tag_count = png_get_uint_32(profile+128);
|
---|
2181 | png_uint_32 itag;
|
---|
2182 | png_const_bytep tag = profile+132; /* The first tag */
|
---|
2183 |
|
---|
2184 | /* First scan all the tags in the table and add bits to the icc_info value
|
---|
2185 | * (temporarily in 'tags').
|
---|
2186 | */
|
---|
2187 | for (itag=0; itag < tag_count; ++itag, tag += 12)
|
---|
2188 | {
|
---|
2189 | png_uint_32 tag_id = png_get_uint_32(tag+0);
|
---|
2190 | png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
|
---|
2191 | png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
|
---|
2192 |
|
---|
2193 | /* The ICC specification does not exclude zero length tags, therefore the
|
---|
2194 | * start might actually be anywhere if there is no data, but this would be
|
---|
2195 | * a clear abuse of the intent of the standard so the start is checked for
|
---|
2196 | * being in range. All defined tag types have an 8 byte header - a 4 byte
|
---|
2197 | * type signature then 0.
|
---|
2198 | */
|
---|
2199 |
|
---|
2200 | /* This is a hard error; potentially it can cause read outside the
|
---|
2201 | * profile.
|
---|
2202 | */
|
---|
2203 | if (tag_start > profile_length || tag_length > profile_length - tag_start)
|
---|
2204 | return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
|
---|
2205 | "ICC profile tag outside profile");
|
---|
2206 |
|
---|
2207 | if ((tag_start & 3) != 0)
|
---|
2208 | {
|
---|
2209 | /* CNHP730S.icc shipped with Microsoft Windows 64 violates this; it is
|
---|
2210 | * only a warning here because libpng does not care about the
|
---|
2211 | * alignment.
|
---|
2212 | */
|
---|
2213 | (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
|
---|
2214 | "ICC profile tag start not a multiple of 4");
|
---|
2215 | }
|
---|
2216 | }
|
---|
2217 |
|
---|
2218 | return 1; /* success, maybe with warnings */
|
---|
2219 | }
|
---|
2220 |
|
---|
2221 | #ifdef PNG_sRGB_SUPPORTED
|
---|
2222 | #if PNG_sRGB_PROFILE_CHECKS >= 0
|
---|
2223 | /* Information about the known ICC sRGB profiles */
|
---|
2224 | static const struct
|
---|
2225 | {
|
---|
2226 | png_uint_32 adler, crc, length;
|
---|
2227 | png_uint_32 md5[4];
|
---|
2228 | png_byte have_md5;
|
---|
2229 | png_byte is_broken;
|
---|
2230 | png_uint_16 intent;
|
---|
2231 |
|
---|
2232 | # define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
|
---|
2233 | # define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
|
---|
2234 | { adler, crc, length, md5, broke, intent },
|
---|
2235 |
|
---|
2236 | } png_sRGB_checks[] =
|
---|
2237 | {
|
---|
2238 | /* This data comes from contrib/tools/checksum-icc run on downloads of
|
---|
2239 | * all four ICC sRGB profiles from www.color.org.
|
---|
2240 | */
|
---|
2241 | /* adler32, crc32, MD5[4], intent, date, length, file-name */
|
---|
2242 | PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
|
---|
2243 | PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
|
---|
2244 | "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
|
---|
2245 |
|
---|
2246 | /* ICC sRGB v2 perceptual no black-compensation: */
|
---|
2247 | PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
|
---|
2248 | PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
|
---|
2249 | "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
|
---|
2250 |
|
---|
2251 | PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
|
---|
2252 | PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
|
---|
2253 | "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
|
---|
2254 |
|
---|
2255 | /* ICC sRGB v4 perceptual */
|
---|
2256 | PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
|
---|
2257 | PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
|
---|
2258 | "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
|
---|
2259 |
|
---|
2260 | /* The following profiles have no known MD5 checksum. If there is a match
|
---|
2261 | * on the (empty) MD5 the other fields are used to attempt a match and
|
---|
2262 | * a warning is produced. The first two of these profiles have a 'cprt' tag
|
---|
2263 | * which suggests that they were also made by Hewlett Packard.
|
---|
2264 | */
|
---|
2265 | PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
|
---|
2266 | PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
|
---|
2267 | "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
|
---|
2268 |
|
---|
2269 | /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
|
---|
2270 | * match the D50 PCS illuminant in the header (it is in fact the D65 values,
|
---|
2271 | * so the white point is recorded as the un-adapted value.) The profiles
|
---|
2272 | * below only differ in one byte - the intent - and are basically the same as
|
---|
2273 | * the previous profile except for the mediaWhitePointTag error and a missing
|
---|
2274 | * chromaticAdaptationTag.
|
---|
2275 | */
|
---|
2276 | PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
|
---|
2277 | PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
|
---|
2278 | "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
|
---|
2279 |
|
---|
2280 | PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
|
---|
2281 | PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
|
---|
2282 | "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
|
---|
2283 | };
|
---|
2284 |
|
---|
2285 | static int
|
---|
2286 | png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
|
---|
2287 | png_const_bytep profile, uLong adler)
|
---|
2288 | {
|
---|
2289 | /* The quick check is to verify just the MD5 signature and trust the
|
---|
2290 | * rest of the data. Because the profile has already been verified for
|
---|
2291 | * correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
|
---|
2292 | * field too, so if the profile has been edited with an intent not defined
|
---|
2293 | * by sRGB (but maybe defined by a later ICC specification) the read of
|
---|
2294 | * the profile will fail at that point.
|
---|
2295 | */
|
---|
2296 |
|
---|
2297 | png_uint_32 length = 0;
|
---|
2298 | png_uint_32 intent = 0x10000; /* invalid */
|
---|
2299 | #if PNG_sRGB_PROFILE_CHECKS > 1
|
---|
2300 | uLong crc = 0; /* the value for 0 length data */
|
---|
2301 | #endif
|
---|
2302 | unsigned int i;
|
---|
2303 |
|
---|
2304 | #ifdef PNG_SET_OPTION_SUPPORTED
|
---|
2305 | /* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
|
---|
2306 | if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
|
---|
2307 | PNG_OPTION_ON)
|
---|
2308 | return 0;
|
---|
2309 | #endif
|
---|
2310 |
|
---|
2311 | for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
|
---|
2312 | {
|
---|
2313 | if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
|
---|
2314 | png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
|
---|
2315 | png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
|
---|
2316 | png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
|
---|
2317 | {
|
---|
2318 | /* This may be one of the old HP profiles without an MD5, in that
|
---|
2319 | * case we can only use the length and Adler32 (note that these
|
---|
2320 | * are not used by default if there is an MD5!)
|
---|
2321 | */
|
---|
2322 | # if PNG_sRGB_PROFILE_CHECKS == 0
|
---|
2323 | if (png_sRGB_checks[i].have_md5 != 0)
|
---|
2324 | return 1+png_sRGB_checks[i].is_broken;
|
---|
2325 | # endif
|
---|
2326 |
|
---|
2327 | /* Profile is unsigned or more checks have been configured in. */
|
---|
2328 | if (length == 0)
|
---|
2329 | {
|
---|
2330 | length = png_get_uint_32(profile);
|
---|
2331 | intent = png_get_uint_32(profile+64);
|
---|
2332 | }
|
---|
2333 |
|
---|
2334 | /* Length *and* intent must match */
|
---|
2335 | if (length == (png_uint_32) png_sRGB_checks[i].length &&
|
---|
2336 | intent == (png_uint_32) png_sRGB_checks[i].intent)
|
---|
2337 | {
|
---|
2338 | /* Now calculate the adler32 if not done already. */
|
---|
2339 | if (adler == 0)
|
---|
2340 | {
|
---|
2341 | adler = adler32(0, NULL, 0);
|
---|
2342 | adler = adler32(adler, profile, length);
|
---|
2343 | }
|
---|
2344 |
|
---|
2345 | if (adler == png_sRGB_checks[i].adler)
|
---|
2346 | {
|
---|
2347 | /* These basic checks suggest that the data has not been
|
---|
2348 | * modified, but if the check level is more than 1 perform
|
---|
2349 | * our own crc32 checksum on the data.
|
---|
2350 | */
|
---|
2351 | # if PNG_sRGB_PROFILE_CHECKS > 1
|
---|
2352 | if (crc == 0)
|
---|
2353 | {
|
---|
2354 | crc = crc32(0, NULL, 0);
|
---|
2355 | crc = crc32(crc, profile, length);
|
---|
2356 | }
|
---|
2357 |
|
---|
2358 | /* So this check must pass for the 'return' below to happen.
|
---|
2359 | */
|
---|
2360 | if (crc == png_sRGB_checks[i].crc)
|
---|
2361 | # endif
|
---|
2362 | {
|
---|
2363 | if (png_sRGB_checks[i].is_broken != 0)
|
---|
2364 | {
|
---|
2365 | /* These profiles are known to have bad data that may cause
|
---|
2366 | * problems if they are used, therefore attempt to
|
---|
2367 | * discourage their use, skip the 'have_md5' warning below,
|
---|
2368 | * which is made irrelevant by this error.
|
---|
2369 | */
|
---|
2370 | png_chunk_report(png_ptr, "known incorrect sRGB profile",
|
---|
2371 | PNG_CHUNK_ERROR);
|
---|
2372 | }
|
---|
2373 |
|
---|
2374 | /* Warn that this being done; this isn't even an error since
|
---|
2375 | * the profile is perfectly valid, but it would be nice if
|
---|
2376 | * people used the up-to-date ones.
|
---|
2377 | */
|
---|
2378 | else if (png_sRGB_checks[i].have_md5 == 0)
|
---|
2379 | {
|
---|
2380 | png_chunk_report(png_ptr,
|
---|
2381 | "out-of-date sRGB profile with no signature",
|
---|
2382 | PNG_CHUNK_WARNING);
|
---|
2383 | }
|
---|
2384 |
|
---|
2385 | return 1+png_sRGB_checks[i].is_broken;
|
---|
2386 | }
|
---|
2387 | }
|
---|
2388 |
|
---|
2389 | # if PNG_sRGB_PROFILE_CHECKS > 0
|
---|
2390 | /* The signature matched, but the profile had been changed in some
|
---|
2391 | * way. This probably indicates a data error or uninformed hacking.
|
---|
2392 | * Fall through to "no match".
|
---|
2393 | */
|
---|
2394 | png_chunk_report(png_ptr,
|
---|
2395 | "Not recognizing known sRGB profile that has been edited",
|
---|
2396 | PNG_CHUNK_WARNING);
|
---|
2397 | break;
|
---|
2398 | # endif
|
---|
2399 | }
|
---|
2400 | }
|
---|
2401 | }
|
---|
2402 |
|
---|
2403 | return 0; /* no match */
|
---|
2404 | }
|
---|
2405 |
|
---|
2406 | void /* PRIVATE */
|
---|
2407 | png_icc_set_sRGB(png_const_structrp png_ptr,
|
---|
2408 | png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
|
---|
2409 | {
|
---|
2410 | /* Is this profile one of the known ICC sRGB profiles? If it is, just set
|
---|
2411 | * the sRGB information.
|
---|
2412 | */
|
---|
2413 | if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
|
---|
2414 | (void)png_colorspace_set_sRGB(png_ptr, colorspace,
|
---|
2415 | (int)/*already checked*/png_get_uint_32(profile+64));
|
---|
2416 | }
|
---|
2417 | #endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
|
---|
2418 | #endif /* sRGB */
|
---|
2419 |
|
---|
2420 | int /* PRIVATE */
|
---|
2421 | png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
---|
2422 | png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
|
---|
2423 | int color_type)
|
---|
2424 | {
|
---|
2425 | if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
---|
2426 | return 0;
|
---|
2427 |
|
---|
2428 | if (icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
|
---|
2429 | png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
|
---|
2430 | color_type) != 0 &&
|
---|
2431 | png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
|
---|
2432 | profile) != 0)
|
---|
2433 | {
|
---|
2434 | # if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
|
---|
2435 | /* If no sRGB support, don't try storing sRGB information */
|
---|
2436 | png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
|
---|
2437 | # endif
|
---|
2438 | return 1;
|
---|
2439 | }
|
---|
2440 |
|
---|
2441 | /* Failure case */
|
---|
2442 | return 0;
|
---|
2443 | }
|
---|
2444 | #endif /* iCCP */
|
---|
2445 |
|
---|
2446 | #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
|
---|
2447 | void /* PRIVATE */
|
---|
2448 | png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
|
---|
2449 | {
|
---|
2450 | /* Set the rgb_to_gray coefficients from the colorspace. */
|
---|
2451 | if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
|
---|
2452 | (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
---|
2453 | {
|
---|
2454 | /* png_set_background has not been called, get the coefficients from the Y
|
---|
2455 | * values of the colorspace colorants.
|
---|
2456 | */
|
---|
2457 | png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
|
---|
2458 | png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
|
---|
2459 | png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
|
---|
2460 | png_fixed_point total = r+g+b;
|
---|
2461 |
|
---|
2462 | if (total > 0 &&
|
---|
2463 | r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
|
---|
2464 | g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
|
---|
2465 | b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
|
---|
2466 | r+g+b <= 32769)
|
---|
2467 | {
|
---|
2468 | /* We allow 0 coefficients here. r+g+b may be 32769 if two or
|
---|
2469 | * all of the coefficients were rounded up. Handle this by
|
---|
2470 | * reducing the *largest* coefficient by 1; this matches the
|
---|
2471 | * approach used for the default coefficients in pngrtran.c
|
---|
2472 | */
|
---|
2473 | int add = 0;
|
---|
2474 |
|
---|
2475 | if (r+g+b > 32768)
|
---|
2476 | add = -1;
|
---|
2477 | else if (r+g+b < 32768)
|
---|
2478 | add = 1;
|
---|
2479 |
|
---|
2480 | if (add != 0)
|
---|
2481 | {
|
---|
2482 | if (g >= r && g >= b)
|
---|
2483 | g += add;
|
---|
2484 | else if (r >= g && r >= b)
|
---|
2485 | r += add;
|
---|
2486 | else
|
---|
2487 | b += add;
|
---|
2488 | }
|
---|
2489 |
|
---|
2490 | /* Check for an internal error. */
|
---|
2491 | if (r+g+b != 32768)
|
---|
2492 | png_error(png_ptr,
|
---|
2493 | "internal error handling cHRM coefficients");
|
---|
2494 |
|
---|
2495 | else
|
---|
2496 | {
|
---|
2497 | png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
|
---|
2498 | png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
|
---|
2499 | }
|
---|
2500 | }
|
---|
2501 |
|
---|
2502 | /* This is a png_error at present even though it could be ignored -
|
---|
2503 | * it should never happen, but it is important that if it does, the
|
---|
2504 | * bug is fixed.
|
---|
2505 | */
|
---|
2506 | else
|
---|
2507 | png_error(png_ptr, "internal error handling cHRM->XYZ");
|
---|
2508 | }
|
---|
2509 | }
|
---|
2510 | #endif /* READ_RGB_TO_GRAY */
|
---|
2511 |
|
---|
2512 | #endif /* COLORSPACE */
|
---|
2513 |
|
---|
2514 | #ifdef __GNUC__
|
---|
2515 | /* This exists solely to work round a warning from GNU C. */
|
---|
2516 | static int /* PRIVATE */
|
---|
2517 | png_gt(size_t a, size_t b)
|
---|
2518 | {
|
---|
2519 | return a > b;
|
---|
2520 | }
|
---|
2521 | #else
|
---|
2522 | # define png_gt(a,b) ((a) > (b))
|
---|
2523 | #endif
|
---|
2524 |
|
---|
2525 | void /* PRIVATE */
|
---|
2526 | png_check_IHDR(png_const_structrp png_ptr,
|
---|
2527 | png_uint_32 width, png_uint_32 height, int bit_depth,
|
---|
2528 | int color_type, int interlace_type, int compression_type,
|
---|
2529 | int filter_type)
|
---|
2530 | {
|
---|
2531 | int error = 0;
|
---|
2532 |
|
---|
2533 | /* Check for width and height valid values */
|
---|
2534 | if (width == 0)
|
---|
2535 | {
|
---|
2536 | png_warning(png_ptr, "Image width is zero in IHDR");
|
---|
2537 | error = 1;
|
---|
2538 | }
|
---|
2539 |
|
---|
2540 | if (width > PNG_UINT_31_MAX)
|
---|
2541 | {
|
---|
2542 | png_warning(png_ptr, "Invalid image width in IHDR");
|
---|
2543 | error = 1;
|
---|
2544 | }
|
---|
2545 |
|
---|
2546 | if (png_gt(((width + 7) & (~7U)),
|
---|
2547 | ((PNG_SIZE_MAX
|
---|
2548 | - 48 /* big_row_buf hack */
|
---|
2549 | - 1) /* filter byte */
|
---|
2550 | / 8) /* 8-byte RGBA pixels */
|
---|
2551 | - 1)) /* extra max_pixel_depth pad */
|
---|
2552 | {
|
---|
2553 | /* The size of the row must be within the limits of this architecture.
|
---|
2554 | * Because the read code can perform arbitrary transformations the
|
---|
2555 | * maximum size is checked here. Because the code in png_read_start_row
|
---|
2556 | * adds extra space "for safety's sake" in several places a conservative
|
---|
2557 | * limit is used here.
|
---|
2558 | *
|
---|
2559 | * NOTE: it would be far better to check the size that is actually used,
|
---|
2560 | * but the effect in the real world is minor and the changes are more
|
---|
2561 | * extensive, therefore much more dangerous and much more difficult to
|
---|
2562 | * write in a way that avoids compiler warnings.
|
---|
2563 | */
|
---|
2564 | png_warning(png_ptr, "Image width is too large for this architecture");
|
---|
2565 | error = 1;
|
---|
2566 | }
|
---|
2567 |
|
---|
2568 | #ifdef PNG_SET_USER_LIMITS_SUPPORTED
|
---|
2569 | if (width > png_ptr->user_width_max)
|
---|
2570 | #else
|
---|
2571 | if (width > PNG_USER_WIDTH_MAX)
|
---|
2572 | #endif
|
---|
2573 | {
|
---|
2574 | png_warning(png_ptr, "Image width exceeds user limit in IHDR");
|
---|
2575 | error = 1;
|
---|
2576 | }
|
---|
2577 |
|
---|
2578 | if (height == 0)
|
---|
2579 | {
|
---|
2580 | png_warning(png_ptr, "Image height is zero in IHDR");
|
---|
2581 | error = 1;
|
---|
2582 | }
|
---|
2583 |
|
---|
2584 | if (height > PNG_UINT_31_MAX)
|
---|
2585 | {
|
---|
2586 | png_warning(png_ptr, "Invalid image height in IHDR");
|
---|
2587 | error = 1;
|
---|
2588 | }
|
---|
2589 |
|
---|
2590 | #ifdef PNG_SET_USER_LIMITS_SUPPORTED
|
---|
2591 | if (height > png_ptr->user_height_max)
|
---|
2592 | #else
|
---|
2593 | if (height > PNG_USER_HEIGHT_MAX)
|
---|
2594 | #endif
|
---|
2595 | {
|
---|
2596 | png_warning(png_ptr, "Image height exceeds user limit in IHDR");
|
---|
2597 | error = 1;
|
---|
2598 | }
|
---|
2599 |
|
---|
2600 | /* Check other values */
|
---|
2601 | if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
|
---|
2602 | bit_depth != 8 && bit_depth != 16)
|
---|
2603 | {
|
---|
2604 | png_warning(png_ptr, "Invalid bit depth in IHDR");
|
---|
2605 | error = 1;
|
---|
2606 | }
|
---|
2607 |
|
---|
2608 | if (color_type < 0 || color_type == 1 ||
|
---|
2609 | color_type == 5 || color_type > 6)
|
---|
2610 | {
|
---|
2611 | png_warning(png_ptr, "Invalid color type in IHDR");
|
---|
2612 | error = 1;
|
---|
2613 | }
|
---|
2614 |
|
---|
2615 | if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
|
---|
2616 | ((color_type == PNG_COLOR_TYPE_RGB ||
|
---|
2617 | color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
|
---|
2618 | color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
|
---|
2619 | {
|
---|
2620 | png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
|
---|
2621 | error = 1;
|
---|
2622 | }
|
---|
2623 |
|
---|
2624 | if (interlace_type >= PNG_INTERLACE_LAST)
|
---|
2625 | {
|
---|
2626 | png_warning(png_ptr, "Unknown interlace method in IHDR");
|
---|
2627 | error = 1;
|
---|
2628 | }
|
---|
2629 |
|
---|
2630 | if (compression_type != PNG_COMPRESSION_TYPE_BASE)
|
---|
2631 | {
|
---|
2632 | png_warning(png_ptr, "Unknown compression method in IHDR");
|
---|
2633 | error = 1;
|
---|
2634 | }
|
---|
2635 |
|
---|
2636 | #ifdef PNG_MNG_FEATURES_SUPPORTED
|
---|
2637 | /* Accept filter_method 64 (intrapixel differencing) only if
|
---|
2638 | * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
|
---|
2639 | * 2. Libpng did not read a PNG signature (this filter_method is only
|
---|
2640 | * used in PNG datastreams that are embedded in MNG datastreams) and
|
---|
2641 | * 3. The application called png_permit_mng_features with a mask that
|
---|
2642 | * included PNG_FLAG_MNG_FILTER_64 and
|
---|
2643 | * 4. The filter_method is 64 and
|
---|
2644 | * 5. The color_type is RGB or RGBA
|
---|
2645 | */
|
---|
2646 | if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
|
---|
2647 | png_ptr->mng_features_permitted != 0)
|
---|
2648 | png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
|
---|
2649 |
|
---|
2650 | if (filter_type != PNG_FILTER_TYPE_BASE)
|
---|
2651 | {
|
---|
2652 | if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
|
---|
2653 | (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
|
---|
2654 | ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
|
---|
2655 | (color_type == PNG_COLOR_TYPE_RGB ||
|
---|
2656 | color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
|
---|
2657 | {
|
---|
2658 | png_warning(png_ptr, "Unknown filter method in IHDR");
|
---|
2659 | error = 1;
|
---|
2660 | }
|
---|
2661 |
|
---|
2662 | if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
|
---|
2663 | {
|
---|
2664 | png_warning(png_ptr, "Invalid filter method in IHDR");
|
---|
2665 | error = 1;
|
---|
2666 | }
|
---|
2667 | }
|
---|
2668 |
|
---|
2669 | #else
|
---|
2670 | if (filter_type != PNG_FILTER_TYPE_BASE)
|
---|
2671 | {
|
---|
2672 | png_warning(png_ptr, "Unknown filter method in IHDR");
|
---|
2673 | error = 1;
|
---|
2674 | }
|
---|
2675 | #endif
|
---|
2676 |
|
---|
2677 | if (error == 1)
|
---|
2678 | png_error(png_ptr, "Invalid IHDR data");
|
---|
2679 | }
|
---|
2680 |
|
---|
2681 | #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
|
---|
2682 | /* ASCII to fp functions */
|
---|
2683 | /* Check an ASCII formatted floating point value, see the more detailed
|
---|
2684 | * comments in pngpriv.h
|
---|
2685 | */
|
---|
2686 | /* The following is used internally to preserve the sticky flags */
|
---|
2687 | #define png_fp_add(state, flags) ((state) |= (flags))
|
---|
2688 | #define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
|
---|
2689 |
|
---|
2690 | int /* PRIVATE */
|
---|
2691 | png_check_fp_number(png_const_charp string, size_t size, int *statep,
|
---|
2692 | size_t *whereami)
|
---|
2693 | {
|
---|
2694 | int state = *statep;
|
---|
2695 | size_t i = *whereami;
|
---|
2696 |
|
---|
2697 | while (i < size)
|
---|
2698 | {
|
---|
2699 | int type;
|
---|
2700 | /* First find the type of the next character */
|
---|
2701 | switch (string[i])
|
---|
2702 | {
|
---|
2703 | case 43: type = PNG_FP_SAW_SIGN; break;
|
---|
2704 | case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
|
---|
2705 | case 46: type = PNG_FP_SAW_DOT; break;
|
---|
2706 | case 48: type = PNG_FP_SAW_DIGIT; break;
|
---|
2707 | case 49: case 50: case 51: case 52:
|
---|
2708 | case 53: case 54: case 55: case 56:
|
---|
2709 | case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
|
---|
2710 | case 69:
|
---|
2711 | case 101: type = PNG_FP_SAW_E; break;
|
---|
2712 | default: goto PNG_FP_End;
|
---|
2713 | }
|
---|
2714 |
|
---|
2715 | /* Now deal with this type according to the current
|
---|
2716 | * state, the type is arranged to not overlap the
|
---|
2717 | * bits of the PNG_FP_STATE.
|
---|
2718 | */
|
---|
2719 | switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
|
---|
2720 | {
|
---|
2721 | case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
|
---|
2722 | if ((state & PNG_FP_SAW_ANY) != 0)
|
---|
2723 | goto PNG_FP_End; /* not a part of the number */
|
---|
2724 |
|
---|
2725 | png_fp_add(state, type);
|
---|
2726 | break;
|
---|
2727 |
|
---|
2728 | case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
|
---|
2729 | /* Ok as trailer, ok as lead of fraction. */
|
---|
2730 | if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
|
---|
2731 | goto PNG_FP_End;
|
---|
2732 |
|
---|
2733 | else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
|
---|
2734 | png_fp_add(state, type);
|
---|
2735 |
|
---|
2736 | else
|
---|
2737 | png_fp_set(state, PNG_FP_FRACTION | type);
|
---|
2738 |
|
---|
2739 | break;
|
---|
2740 |
|
---|
2741 | case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
|
---|
2742 | if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
|
---|
2743 | png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
|
---|
2744 |
|
---|
2745 | png_fp_add(state, type | PNG_FP_WAS_VALID);
|
---|
2746 |
|
---|
2747 | break;
|
---|
2748 |
|
---|
2749 | case PNG_FP_INTEGER + PNG_FP_SAW_E:
|
---|
2750 | if ((state & PNG_FP_SAW_DIGIT) == 0)
|
---|
2751 | goto PNG_FP_End;
|
---|
2752 |
|
---|
2753 | png_fp_set(state, PNG_FP_EXPONENT);
|
---|
2754 |
|
---|
2755 | break;
|
---|
2756 |
|
---|
2757 | /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
|
---|
2758 | goto PNG_FP_End; ** no sign in fraction */
|
---|
2759 |
|
---|
2760 | /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
|
---|
2761 | goto PNG_FP_End; ** Because SAW_DOT is always set */
|
---|
2762 |
|
---|
2763 | case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
|
---|
2764 | png_fp_add(state, type | PNG_FP_WAS_VALID);
|
---|
2765 | break;
|
---|
2766 |
|
---|
2767 | case PNG_FP_FRACTION + PNG_FP_SAW_E:
|
---|
2768 | /* This is correct because the trailing '.' on an
|
---|
2769 | * integer is handled above - so we can only get here
|
---|
2770 | * with the sequence ".E" (with no preceding digits).
|
---|
2771 | */
|
---|
2772 | if ((state & PNG_FP_SAW_DIGIT) == 0)
|
---|
2773 | goto PNG_FP_End;
|
---|
2774 |
|
---|
2775 | png_fp_set(state, PNG_FP_EXPONENT);
|
---|
2776 |
|
---|
2777 | break;
|
---|
2778 |
|
---|
2779 | case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
|
---|
2780 | if ((state & PNG_FP_SAW_ANY) != 0)
|
---|
2781 | goto PNG_FP_End; /* not a part of the number */
|
---|
2782 |
|
---|
2783 | png_fp_add(state, PNG_FP_SAW_SIGN);
|
---|
2784 |
|
---|
2785 | break;
|
---|
2786 |
|
---|
2787 | /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
|
---|
2788 | goto PNG_FP_End; */
|
---|
2789 |
|
---|
2790 | case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
|
---|
2791 | png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
|
---|
2792 |
|
---|
2793 | break;
|
---|
2794 |
|
---|
2795 | /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
|
---|
2796 | goto PNG_FP_End; */
|
---|
2797 |
|
---|
2798 | default: goto PNG_FP_End; /* I.e. break 2 */
|
---|
2799 | }
|
---|
2800 |
|
---|
2801 | /* The character seems ok, continue. */
|
---|
2802 | ++i;
|
---|
2803 | }
|
---|
2804 |
|
---|
2805 | PNG_FP_End:
|
---|
2806 | /* Here at the end, update the state and return the correct
|
---|
2807 | * return code.
|
---|
2808 | */
|
---|
2809 | *statep = state;
|
---|
2810 | *whereami = i;
|
---|
2811 |
|
---|
2812 | return (state & PNG_FP_SAW_DIGIT) != 0;
|
---|
2813 | }
|
---|
2814 |
|
---|
2815 |
|
---|
2816 | /* The same but for a complete string. */
|
---|
2817 | int
|
---|
2818 | png_check_fp_string(png_const_charp string, size_t size)
|
---|
2819 | {
|
---|
2820 | int state=0;
|
---|
2821 | size_t char_index=0;
|
---|
2822 |
|
---|
2823 | if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
|
---|
2824 | (char_index == size || string[char_index] == 0))
|
---|
2825 | return state /* must be non-zero - see above */;
|
---|
2826 |
|
---|
2827 | return 0; /* i.e. fail */
|
---|
2828 | }
|
---|
2829 | #endif /* pCAL || sCAL */
|
---|
2830 |
|
---|
2831 | #ifdef PNG_sCAL_SUPPORTED
|
---|
2832 | # ifdef PNG_FLOATING_POINT_SUPPORTED
|
---|
2833 | /* Utility used below - a simple accurate power of ten from an integral
|
---|
2834 | * exponent.
|
---|
2835 | */
|
---|
2836 | static double
|
---|
2837 | png_pow10(int power)
|
---|
2838 | {
|
---|
2839 | int recip = 0;
|
---|
2840 | double d = 1;
|
---|
2841 |
|
---|
2842 | /* Handle negative exponent with a reciprocal at the end because
|
---|
2843 | * 10 is exact whereas .1 is inexact in base 2
|
---|
2844 | */
|
---|
2845 | if (power < 0)
|
---|
2846 | {
|
---|
2847 | if (power < DBL_MIN_10_EXP) return 0;
|
---|
2848 | recip = 1; power = -power;
|
---|
2849 | }
|
---|
2850 |
|
---|
2851 | if (power > 0)
|
---|
2852 | {
|
---|
2853 | /* Decompose power bitwise. */
|
---|
2854 | double mult = 10;
|
---|
2855 | do
|
---|
2856 | {
|
---|
2857 | if (power & 1) d *= mult;
|
---|
2858 | mult *= mult;
|
---|
2859 | power >>= 1;
|
---|
2860 | }
|
---|
2861 | while (power > 0);
|
---|
2862 |
|
---|
2863 | if (recip != 0) d = 1/d;
|
---|
2864 | }
|
---|
2865 | /* else power is 0 and d is 1 */
|
---|
2866 |
|
---|
2867 | return d;
|
---|
2868 | }
|
---|
2869 |
|
---|
2870 | /* Function to format a floating point value in ASCII with a given
|
---|
2871 | * precision.
|
---|
2872 | */
|
---|
2873 | void /* PRIVATE */
|
---|
2874 | png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, size_t size,
|
---|
2875 | double fp, unsigned int precision)
|
---|
2876 | {
|
---|
2877 | /* We use standard functions from math.h, but not printf because
|
---|
2878 | * that would require stdio. The caller must supply a buffer of
|
---|
2879 | * sufficient size or we will png_error. The tests on size and
|
---|
2880 | * the space in ascii[] consumed are indicated below.
|
---|
2881 | */
|
---|
2882 | if (precision < 1)
|
---|
2883 | precision = DBL_DIG;
|
---|
2884 |
|
---|
2885 | /* Enforce the limit of the implementation precision too. */
|
---|
2886 | if (precision > DBL_DIG+1)
|
---|
2887 | precision = DBL_DIG+1;
|
---|
2888 |
|
---|
2889 | /* Basic sanity checks */
|
---|
2890 | if (size >= precision+5) /* See the requirements below. */
|
---|
2891 | {
|
---|
2892 | if (fp < 0)
|
---|
2893 | {
|
---|
2894 | fp = -fp;
|
---|
2895 | *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
|
---|
2896 | --size;
|
---|
2897 | }
|
---|
2898 |
|
---|
2899 | if (fp >= DBL_MIN && fp <= DBL_MAX)
|
---|
2900 | {
|
---|
2901 | int exp_b10; /* A base 10 exponent */
|
---|
2902 | double base; /* 10^exp_b10 */
|
---|
2903 |
|
---|
2904 | /* First extract a base 10 exponent of the number,
|
---|
2905 | * the calculation below rounds down when converting
|
---|
2906 | * from base 2 to base 10 (multiply by log10(2) -
|
---|
2907 | * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
|
---|
2908 | * be increased. Note that the arithmetic shift
|
---|
2909 | * performs a floor() unlike C arithmetic - using a
|
---|
2910 | * C multiply would break the following for negative
|
---|
2911 | * exponents.
|
---|
2912 | */
|
---|
2913 | (void)frexp(fp, &exp_b10); /* exponent to base 2 */
|
---|
2914 |
|
---|
2915 | exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
|
---|
2916 |
|
---|
2917 | /* Avoid underflow here. */
|
---|
2918 | base = png_pow10(exp_b10); /* May underflow */
|
---|
2919 |
|
---|
2920 | while (base < DBL_MIN || base < fp)
|
---|
2921 | {
|
---|
2922 | /* And this may overflow. */
|
---|
2923 | double test = png_pow10(exp_b10+1);
|
---|
2924 |
|
---|
2925 | if (test <= DBL_MAX)
|
---|
2926 | {
|
---|
2927 | ++exp_b10; base = test;
|
---|
2928 | }
|
---|
2929 |
|
---|
2930 | else
|
---|
2931 | break;
|
---|
2932 | }
|
---|
2933 |
|
---|
2934 | /* Normalize fp and correct exp_b10, after this fp is in the
|
---|
2935 | * range [.1,1) and exp_b10 is both the exponent and the digit
|
---|
2936 | * *before* which the decimal point should be inserted
|
---|
2937 | * (starting with 0 for the first digit). Note that this
|
---|
2938 | * works even if 10^exp_b10 is out of range because of the
|
---|
2939 | * test on DBL_MAX above.
|
---|
2940 | */
|
---|
2941 | fp /= base;
|
---|
2942 | while (fp >= 1)
|
---|
2943 | {
|
---|
2944 | fp /= 10; ++exp_b10;
|
---|
2945 | }
|
---|
2946 |
|
---|
2947 | /* Because of the code above fp may, at this point, be
|
---|
2948 | * less than .1, this is ok because the code below can
|
---|
2949 | * handle the leading zeros this generates, so no attempt
|
---|
2950 | * is made to correct that here.
|
---|
2951 | */
|
---|
2952 |
|
---|
2953 | {
|
---|
2954 | unsigned int czero, clead, cdigits;
|
---|
2955 | char exponent[10];
|
---|
2956 |
|
---|
2957 | /* Allow up to two leading zeros - this will not lengthen
|
---|
2958 | * the number compared to using E-n.
|
---|
2959 | */
|
---|
2960 | if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
|
---|
2961 | {
|
---|
2962 | czero = 0U-exp_b10; /* PLUS 2 digits: TOTAL 3 */
|
---|
2963 | exp_b10 = 0; /* Dot added below before first output. */
|
---|
2964 | }
|
---|
2965 | else
|
---|
2966 | czero = 0; /* No zeros to add */
|
---|
2967 |
|
---|
2968 | /* Generate the digit list, stripping trailing zeros and
|
---|
2969 | * inserting a '.' before a digit if the exponent is 0.
|
---|
2970 | */
|
---|
2971 | clead = czero; /* Count of leading zeros */
|
---|
2972 | cdigits = 0; /* Count of digits in list. */
|
---|
2973 |
|
---|
2974 | do
|
---|
2975 | {
|
---|
2976 | double d;
|
---|
2977 |
|
---|
2978 | fp *= 10;
|
---|
2979 | /* Use modf here, not floor and subtract, so that
|
---|
2980 | * the separation is done in one step. At the end
|
---|
2981 | * of the loop don't break the number into parts so
|
---|
2982 | * that the final digit is rounded.
|
---|
2983 | */
|
---|
2984 | if (cdigits+czero+1 < precision+clead)
|
---|
2985 | fp = modf(fp, &d);
|
---|
2986 |
|
---|
2987 | else
|
---|
2988 | {
|
---|
2989 | d = floor(fp + .5);
|
---|
2990 |
|
---|
2991 | if (d > 9)
|
---|
2992 | {
|
---|
2993 | /* Rounding up to 10, handle that here. */
|
---|
2994 | if (czero > 0)
|
---|
2995 | {
|
---|
2996 | --czero; d = 1;
|
---|
2997 | if (cdigits == 0) --clead;
|
---|
2998 | }
|
---|
2999 | else
|
---|
3000 | {
|
---|
3001 | while (cdigits > 0 && d > 9)
|
---|
3002 | {
|
---|
3003 | int ch = *--ascii;
|
---|
3004 |
|
---|
3005 | if (exp_b10 != (-1))
|
---|
3006 | ++exp_b10;
|
---|
3007 |
|
---|
3008 | else if (ch == 46)
|
---|
3009 | {
|
---|
3010 | ch = *--ascii; ++size;
|
---|
3011 | /* Advance exp_b10 to '1', so that the
|
---|
3012 | * decimal point happens after the
|
---|
3013 | * previous digit.
|
---|
3014 | */
|
---|
3015 | exp_b10 = 1;
|
---|
3016 | }
|
---|
3017 |
|
---|
3018 | --cdigits;
|
---|
3019 | d = ch - 47; /* I.e. 1+(ch-48) */
|
---|
3020 | }
|
---|
3021 |
|
---|
3022 | /* Did we reach the beginning? If so adjust the
|
---|
3023 | * exponent but take into account the leading
|
---|
3024 | * decimal point.
|
---|
3025 | */
|
---|
3026 | if (d > 9) /* cdigits == 0 */
|
---|
3027 | {
|
---|
3028 | if (exp_b10 == (-1))
|
---|
3029 | {
|
---|
3030 | /* Leading decimal point (plus zeros?), if
|
---|
3031 | * we lose the decimal point here it must
|
---|
3032 | * be reentered below.
|
---|
3033 | */
|
---|
3034 | int ch = *--ascii;
|
---|
3035 |
|
---|
3036 | if (ch == 46)
|
---|
3037 | {
|
---|
3038 | ++size; exp_b10 = 1;
|
---|
3039 | }
|
---|
3040 |
|
---|
3041 | /* Else lost a leading zero, so 'exp_b10' is
|
---|
3042 | * still ok at (-1)
|
---|
3043 | */
|
---|
3044 | }
|
---|
3045 | else
|
---|
3046 | ++exp_b10;
|
---|
3047 |
|
---|
3048 | /* In all cases we output a '1' */
|
---|
3049 | d = 1;
|
---|
3050 | }
|
---|
3051 | }
|
---|
3052 | }
|
---|
3053 | fp = 0; /* Guarantees termination below. */
|
---|
3054 | }
|
---|
3055 |
|
---|
3056 | if (d == 0)
|
---|
3057 | {
|
---|
3058 | ++czero;
|
---|
3059 | if (cdigits == 0) ++clead;
|
---|
3060 | }
|
---|
3061 | else
|
---|
3062 | {
|
---|
3063 | /* Included embedded zeros in the digit count. */
|
---|
3064 | cdigits += czero - clead;
|
---|
3065 | clead = 0;
|
---|
3066 |
|
---|
3067 | while (czero > 0)
|
---|
3068 | {
|
---|
3069 | /* exp_b10 == (-1) means we just output the decimal
|
---|
3070 | * place - after the DP don't adjust 'exp_b10' any
|
---|
3071 | * more!
|
---|
3072 | */
|
---|
3073 | if (exp_b10 != (-1))
|
---|
3074 | {
|
---|
3075 | if (exp_b10 == 0)
|
---|
3076 | {
|
---|
3077 | *ascii++ = 46; --size;
|
---|
3078 | }
|
---|
3079 | /* PLUS 1: TOTAL 4 */
|
---|
3080 | --exp_b10;
|
---|
3081 | }
|
---|
3082 | *ascii++ = 48; --czero;
|
---|
3083 | }
|
---|
3084 |
|
---|
3085 | if (exp_b10 != (-1))
|
---|
3086 | {
|
---|
3087 | if (exp_b10 == 0)
|
---|
3088 | {
|
---|
3089 | *ascii++ = 46; --size; /* counted above */
|
---|
3090 | }
|
---|
3091 |
|
---|
3092 | --exp_b10;
|
---|
3093 | }
|
---|
3094 | *ascii++ = (char)(48 + (int)d); ++cdigits;
|
---|
3095 | }
|
---|
3096 | }
|
---|
3097 | while (cdigits+czero < precision+clead && fp > DBL_MIN);
|
---|
3098 |
|
---|
3099 | /* The total output count (max) is now 4+precision */
|
---|
3100 |
|
---|
3101 | /* Check for an exponent, if we don't need one we are
|
---|
3102 | * done and just need to terminate the string. At this
|
---|
3103 | * point, exp_b10==(-1) is effectively a flag: it got
|
---|
3104 | * to '-1' because of the decrement, after outputting
|
---|
3105 | * the decimal point above. (The exponent required is
|
---|
3106 | * *not* -1.)
|
---|
3107 | */
|
---|
3108 | if (exp_b10 >= (-1) && exp_b10 <= 2)
|
---|
3109 | {
|
---|
3110 | /* The following only happens if we didn't output the
|
---|
3111 | * leading zeros above for negative exponent, so this
|
---|
3112 | * doesn't add to the digit requirement. Note that the
|
---|
3113 | * two zeros here can only be output if the two leading
|
---|
3114 | * zeros were *not* output, so this doesn't increase
|
---|
3115 | * the output count.
|
---|
3116 | */
|
---|
3117 | while (exp_b10-- > 0) *ascii++ = 48;
|
---|
3118 |
|
---|
3119 | *ascii = 0;
|
---|
3120 |
|
---|
3121 | /* Total buffer requirement (including the '\0') is
|
---|
3122 | * 5+precision - see check at the start.
|
---|
3123 | */
|
---|
3124 | return;
|
---|
3125 | }
|
---|
3126 |
|
---|
3127 | /* Here if an exponent is required, adjust size for
|
---|
3128 | * the digits we output but did not count. The total
|
---|
3129 | * digit output here so far is at most 1+precision - no
|
---|
3130 | * decimal point and no leading or trailing zeros have
|
---|
3131 | * been output.
|
---|
3132 | */
|
---|
3133 | size -= cdigits;
|
---|
3134 |
|
---|
3135 | *ascii++ = 69; --size; /* 'E': PLUS 1 TOTAL 2+precision */
|
---|
3136 |
|
---|
3137 | /* The following use of an unsigned temporary avoids ambiguities in
|
---|
3138 | * the signed arithmetic on exp_b10 and permits GCC at least to do
|
---|
3139 | * better optimization.
|
---|
3140 | */
|
---|
3141 | {
|
---|
3142 | unsigned int uexp_b10;
|
---|
3143 |
|
---|
3144 | if (exp_b10 < 0)
|
---|
3145 | {
|
---|
3146 | *ascii++ = 45; --size; /* '-': PLUS 1 TOTAL 3+precision */
|
---|
3147 | uexp_b10 = 0U-exp_b10;
|
---|
3148 | }
|
---|
3149 |
|
---|
3150 | else
|
---|
3151 | uexp_b10 = 0U+exp_b10;
|
---|
3152 |
|
---|
3153 | cdigits = 0;
|
---|
3154 |
|
---|
3155 | while (uexp_b10 > 0)
|
---|
3156 | {
|
---|
3157 | exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
|
---|
3158 | uexp_b10 /= 10;
|
---|
3159 | }
|
---|
3160 | }
|
---|
3161 |
|
---|
3162 | /* Need another size check here for the exponent digits, so
|
---|
3163 | * this need not be considered above.
|
---|
3164 | */
|
---|
3165 | if (size > cdigits)
|
---|
3166 | {
|
---|
3167 | while (cdigits > 0) *ascii++ = exponent[--cdigits];
|
---|
3168 |
|
---|
3169 | *ascii = 0;
|
---|
3170 |
|
---|
3171 | return;
|
---|
3172 | }
|
---|
3173 | }
|
---|
3174 | }
|
---|
3175 | else if (!(fp >= DBL_MIN))
|
---|
3176 | {
|
---|
3177 | *ascii++ = 48; /* '0' */
|
---|
3178 | *ascii = 0;
|
---|
3179 | return;
|
---|
3180 | }
|
---|
3181 | else
|
---|
3182 | {
|
---|
3183 | *ascii++ = 105; /* 'i' */
|
---|
3184 | *ascii++ = 110; /* 'n' */
|
---|
3185 | *ascii++ = 102; /* 'f' */
|
---|
3186 | *ascii = 0;
|
---|
3187 | return;
|
---|
3188 | }
|
---|
3189 | }
|
---|
3190 |
|
---|
3191 | /* Here on buffer too small. */
|
---|
3192 | png_error(png_ptr, "ASCII conversion buffer too small");
|
---|
3193 | }
|
---|
3194 | # endif /* FLOATING_POINT */
|
---|
3195 |
|
---|
3196 | # ifdef PNG_FIXED_POINT_SUPPORTED
|
---|
3197 | /* Function to format a fixed point value in ASCII.
|
---|
3198 | */
|
---|
3199 | void /* PRIVATE */
|
---|
3200 | png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
|
---|
3201 | size_t size, png_fixed_point fp)
|
---|
3202 | {
|
---|
3203 | /* Require space for 10 decimal digits, a decimal point, a minus sign and a
|
---|
3204 | * trailing \0, 13 characters:
|
---|
3205 | */
|
---|
3206 | if (size > 12)
|
---|
3207 | {
|
---|
3208 | png_uint_32 num;
|
---|
3209 |
|
---|
3210 | /* Avoid overflow here on the minimum integer. */
|
---|
3211 | if (fp < 0)
|
---|
3212 | {
|
---|
3213 | *ascii++ = 45; num = (png_uint_32)(-fp);
|
---|
3214 | }
|
---|
3215 | else
|
---|
3216 | num = (png_uint_32)fp;
|
---|
3217 |
|
---|
3218 | if (num <= 0x80000000) /* else overflowed */
|
---|
3219 | {
|
---|
3220 | unsigned int ndigits = 0, first = 16 /* flag value */;
|
---|
3221 | char digits[10] = {0};
|
---|
3222 |
|
---|
3223 | while (num)
|
---|
3224 | {
|
---|
3225 | /* Split the low digit off num: */
|
---|
3226 | unsigned int tmp = num/10;
|
---|
3227 | num -= tmp*10;
|
---|
3228 | digits[ndigits++] = (char)(48 + num);
|
---|
3229 | /* Record the first non-zero digit, note that this is a number
|
---|
3230 | * starting at 1, it's not actually the array index.
|
---|
3231 | */
|
---|
3232 | if (first == 16 && num > 0)
|
---|
3233 | first = ndigits;
|
---|
3234 | num = tmp;
|
---|
3235 | }
|
---|
3236 |
|
---|
3237 | if (ndigits > 0)
|
---|
3238 | {
|
---|
3239 | while (ndigits > 5) *ascii++ = digits[--ndigits];
|
---|
3240 | /* The remaining digits are fractional digits, ndigits is '5' or
|
---|
3241 | * smaller at this point. It is certainly not zero. Check for a
|
---|
3242 | * non-zero fractional digit:
|
---|
3243 | */
|
---|
3244 | if (first <= 5)
|
---|
3245 | {
|
---|
3246 | unsigned int i;
|
---|
3247 | *ascii++ = 46; /* decimal point */
|
---|
3248 | /* ndigits may be <5 for small numbers, output leading zeros
|
---|
3249 | * then ndigits digits to first:
|
---|
3250 | */
|
---|
3251 | i = 5;
|
---|
3252 | while (ndigits < i)
|
---|
3253 | {
|
---|
3254 | *ascii++ = 48; --i;
|
---|
3255 | }
|
---|
3256 | while (ndigits >= first) *ascii++ = digits[--ndigits];
|
---|
3257 | /* Don't output the trailing zeros! */
|
---|
3258 | }
|
---|
3259 | }
|
---|
3260 | else
|
---|
3261 | *ascii++ = 48;
|
---|
3262 |
|
---|
3263 | /* And null terminate the string: */
|
---|
3264 | *ascii = 0;
|
---|
3265 | return;
|
---|
3266 | }
|
---|
3267 | }
|
---|
3268 |
|
---|
3269 | /* Here on buffer too small. */
|
---|
3270 | png_error(png_ptr, "ASCII conversion buffer too small");
|
---|
3271 | }
|
---|
3272 | # endif /* FIXED_POINT */
|
---|
3273 | #endif /* SCAL */
|
---|
3274 |
|
---|
3275 | #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
|
---|
3276 | !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
|
---|
3277 | (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
|
---|
3278 | defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
---|
3279 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
|
---|
3280 | (defined(PNG_sCAL_SUPPORTED) && \
|
---|
3281 | defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
|
---|
3282 | png_fixed_point
|
---|
3283 | png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
|
---|
3284 | {
|
---|
3285 | double r = floor(100000 * fp + .5);
|
---|
3286 |
|
---|
3287 | if (r > 2147483647. || r < -2147483648.)
|
---|
3288 | png_fixed_error(png_ptr, text);
|
---|
3289 |
|
---|
3290 | # ifndef PNG_ERROR_TEXT_SUPPORTED
|
---|
3291 | PNG_UNUSED(text)
|
---|
3292 | # endif
|
---|
3293 |
|
---|
3294 | return (png_fixed_point)r;
|
---|
3295 | }
|
---|
3296 | #endif
|
---|
3297 |
|
---|
3298 | #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
|
---|
3299 | defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
|
---|
3300 | /* muldiv functions */
|
---|
3301 | /* This API takes signed arguments and rounds the result to the nearest
|
---|
3302 | * integer (or, for a fixed point number - the standard argument - to
|
---|
3303 | * the nearest .00001). Overflow and divide by zero are signalled in
|
---|
3304 | * the result, a boolean - true on success, false on overflow.
|
---|
3305 | */
|
---|
3306 | int
|
---|
3307 | png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
|
---|
3308 | png_int_32 divisor)
|
---|
3309 | {
|
---|
3310 | /* Return a * times / divisor, rounded. */
|
---|
3311 | if (divisor != 0)
|
---|
3312 | {
|
---|
3313 | if (a == 0 || times == 0)
|
---|
3314 | {
|
---|
3315 | *res = 0;
|
---|
3316 | return 1;
|
---|
3317 | }
|
---|
3318 | else
|
---|
3319 | {
|
---|
3320 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3321 | double r = a;
|
---|
3322 | r *= times;
|
---|
3323 | r /= divisor;
|
---|
3324 | r = floor(r+.5);
|
---|
3325 |
|
---|
3326 | /* A png_fixed_point is a 32-bit integer. */
|
---|
3327 | if (r <= 2147483647. && r >= -2147483648.)
|
---|
3328 | {
|
---|
3329 | *res = (png_fixed_point)r;
|
---|
3330 | return 1;
|
---|
3331 | }
|
---|
3332 | #else
|
---|
3333 | int negative = 0;
|
---|
3334 | png_uint_32 A, T, D;
|
---|
3335 | png_uint_32 s16, s32, s00;
|
---|
3336 |
|
---|
3337 | if (a < 0)
|
---|
3338 | negative = 1, A = -a;
|
---|
3339 | else
|
---|
3340 | A = a;
|
---|
3341 |
|
---|
3342 | if (times < 0)
|
---|
3343 | negative = !negative, T = -times;
|
---|
3344 | else
|
---|
3345 | T = times;
|
---|
3346 |
|
---|
3347 | if (divisor < 0)
|
---|
3348 | negative = !negative, D = -divisor;
|
---|
3349 | else
|
---|
3350 | D = divisor;
|
---|
3351 |
|
---|
3352 | /* Following can't overflow because the arguments only
|
---|
3353 | * have 31 bits each, however the result may be 32 bits.
|
---|
3354 | */
|
---|
3355 | s16 = (A >> 16) * (T & 0xffff) +
|
---|
3356 | (A & 0xffff) * (T >> 16);
|
---|
3357 | /* Can't overflow because the a*times bit is only 30
|
---|
3358 | * bits at most.
|
---|
3359 | */
|
---|
3360 | s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
|
---|
3361 | s00 = (A & 0xffff) * (T & 0xffff);
|
---|
3362 |
|
---|
3363 | s16 = (s16 & 0xffff) << 16;
|
---|
3364 | s00 += s16;
|
---|
3365 |
|
---|
3366 | if (s00 < s16)
|
---|
3367 | ++s32; /* carry */
|
---|
3368 |
|
---|
3369 | if (s32 < D) /* else overflow */
|
---|
3370 | {
|
---|
3371 | /* s32.s00 is now the 64-bit product, do a standard
|
---|
3372 | * division, we know that s32 < D, so the maximum
|
---|
3373 | * required shift is 31.
|
---|
3374 | */
|
---|
3375 | int bitshift = 32;
|
---|
3376 | png_fixed_point result = 0; /* NOTE: signed */
|
---|
3377 |
|
---|
3378 | while (--bitshift >= 0)
|
---|
3379 | {
|
---|
3380 | png_uint_32 d32, d00;
|
---|
3381 |
|
---|
3382 | if (bitshift > 0)
|
---|
3383 | d32 = D >> (32-bitshift), d00 = D << bitshift;
|
---|
3384 |
|
---|
3385 | else
|
---|
3386 | d32 = 0, d00 = D;
|
---|
3387 |
|
---|
3388 | if (s32 > d32)
|
---|
3389 | {
|
---|
3390 | if (s00 < d00) --s32; /* carry */
|
---|
3391 | s32 -= d32, s00 -= d00, result += 1<<bitshift;
|
---|
3392 | }
|
---|
3393 |
|
---|
3394 | else
|
---|
3395 | if (s32 == d32 && s00 >= d00)
|
---|
3396 | s32 = 0, s00 -= d00, result += 1<<bitshift;
|
---|
3397 | }
|
---|
3398 |
|
---|
3399 | /* Handle the rounding. */
|
---|
3400 | if (s00 >= (D >> 1))
|
---|
3401 | ++result;
|
---|
3402 |
|
---|
3403 | if (negative != 0)
|
---|
3404 | result = -result;
|
---|
3405 |
|
---|
3406 | /* Check for overflow. */
|
---|
3407 | if ((negative != 0 && result <= 0) ||
|
---|
3408 | (negative == 0 && result >= 0))
|
---|
3409 | {
|
---|
3410 | *res = result;
|
---|
3411 | return 1;
|
---|
3412 | }
|
---|
3413 | }
|
---|
3414 | #endif
|
---|
3415 | }
|
---|
3416 | }
|
---|
3417 |
|
---|
3418 | return 0;
|
---|
3419 | }
|
---|
3420 | #endif /* READ_GAMMA || INCH_CONVERSIONS */
|
---|
3421 |
|
---|
3422 | #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
|
---|
3423 | /* The following is for when the caller doesn't much care about the
|
---|
3424 | * result.
|
---|
3425 | */
|
---|
3426 | png_fixed_point
|
---|
3427 | png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
|
---|
3428 | png_int_32 divisor)
|
---|
3429 | {
|
---|
3430 | png_fixed_point result;
|
---|
3431 |
|
---|
3432 | if (png_muldiv(&result, a, times, divisor) != 0)
|
---|
3433 | return result;
|
---|
3434 |
|
---|
3435 | png_warning(png_ptr, "fixed point overflow ignored");
|
---|
3436 | return 0;
|
---|
3437 | }
|
---|
3438 | #endif
|
---|
3439 |
|
---|
3440 | #ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
|
---|
3441 | /* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
|
---|
3442 | png_fixed_point
|
---|
3443 | png_reciprocal(png_fixed_point a)
|
---|
3444 | {
|
---|
3445 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3446 | double r = floor(1E10/a+.5);
|
---|
3447 |
|
---|
3448 | if (r <= 2147483647. && r >= -2147483648.)
|
---|
3449 | return (png_fixed_point)r;
|
---|
3450 | #else
|
---|
3451 | png_fixed_point res;
|
---|
3452 |
|
---|
3453 | if (png_muldiv(&res, 100000, 100000, a) != 0)
|
---|
3454 | return res;
|
---|
3455 | #endif
|
---|
3456 |
|
---|
3457 | return 0; /* error/overflow */
|
---|
3458 | }
|
---|
3459 |
|
---|
3460 | /* This is the shared test on whether a gamma value is 'significant' - whether
|
---|
3461 | * it is worth doing gamma correction.
|
---|
3462 | */
|
---|
3463 | int /* PRIVATE */
|
---|
3464 | png_gamma_significant(png_fixed_point gamma_val)
|
---|
3465 | {
|
---|
3466 | return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
|
---|
3467 | gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
|
---|
3468 | }
|
---|
3469 | #endif
|
---|
3470 |
|
---|
3471 | #ifdef PNG_READ_GAMMA_SUPPORTED
|
---|
3472 | #ifdef PNG_16BIT_SUPPORTED
|
---|
3473 | /* A local convenience routine. */
|
---|
3474 | static png_fixed_point
|
---|
3475 | png_product2(png_fixed_point a, png_fixed_point b)
|
---|
3476 | {
|
---|
3477 | /* The required result is 1/a * 1/b; the following preserves accuracy. */
|
---|
3478 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3479 | double r = a * 1E-5;
|
---|
3480 | r *= b;
|
---|
3481 | r = floor(r+.5);
|
---|
3482 |
|
---|
3483 | if (r <= 2147483647. && r >= -2147483648.)
|
---|
3484 | return (png_fixed_point)r;
|
---|
3485 | #else
|
---|
3486 | png_fixed_point res;
|
---|
3487 |
|
---|
3488 | if (png_muldiv(&res, a, b, 100000) != 0)
|
---|
3489 | return res;
|
---|
3490 | #endif
|
---|
3491 |
|
---|
3492 | return 0; /* overflow */
|
---|
3493 | }
|
---|
3494 | #endif /* 16BIT */
|
---|
3495 |
|
---|
3496 | /* The inverse of the above. */
|
---|
3497 | png_fixed_point
|
---|
3498 | png_reciprocal2(png_fixed_point a, png_fixed_point b)
|
---|
3499 | {
|
---|
3500 | /* The required result is 1/a * 1/b; the following preserves accuracy. */
|
---|
3501 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3502 | if (a != 0 && b != 0)
|
---|
3503 | {
|
---|
3504 | double r = 1E15/a;
|
---|
3505 | r /= b;
|
---|
3506 | r = floor(r+.5);
|
---|
3507 |
|
---|
3508 | if (r <= 2147483647. && r >= -2147483648.)
|
---|
3509 | return (png_fixed_point)r;
|
---|
3510 | }
|
---|
3511 | #else
|
---|
3512 | /* This may overflow because the range of png_fixed_point isn't symmetric,
|
---|
3513 | * but this API is only used for the product of file and screen gamma so it
|
---|
3514 | * doesn't matter that the smallest number it can produce is 1/21474, not
|
---|
3515 | * 1/100000
|
---|
3516 | */
|
---|
3517 | png_fixed_point res = png_product2(a, b);
|
---|
3518 |
|
---|
3519 | if (res != 0)
|
---|
3520 | return png_reciprocal(res);
|
---|
3521 | #endif
|
---|
3522 |
|
---|
3523 | return 0; /* overflow */
|
---|
3524 | }
|
---|
3525 | #endif /* READ_GAMMA */
|
---|
3526 |
|
---|
3527 | #ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
|
---|
3528 | #ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3529 | /* Fixed point gamma.
|
---|
3530 | *
|
---|
3531 | * The code to calculate the tables used below can be found in the shell script
|
---|
3532 | * contrib/tools/intgamma.sh
|
---|
3533 | *
|
---|
3534 | * To calculate gamma this code implements fast log() and exp() calls using only
|
---|
3535 | * fixed point arithmetic. This code has sufficient precision for either 8-bit
|
---|
3536 | * or 16-bit sample values.
|
---|
3537 | *
|
---|
3538 | * The tables used here were calculated using simple 'bc' programs, but C double
|
---|
3539 | * precision floating point arithmetic would work fine.
|
---|
3540 | *
|
---|
3541 | * 8-bit log table
|
---|
3542 | * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
|
---|
3543 | * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
|
---|
3544 | * mantissa. The numbers are 32-bit fractions.
|
---|
3545 | */
|
---|
3546 | static const png_uint_32
|
---|
3547 | png_8bit_l2[128] =
|
---|
3548 | {
|
---|
3549 | 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
|
---|
3550 | 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
|
---|
3551 | 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
|
---|
3552 | 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
|
---|
3553 | 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
|
---|
3554 | 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
|
---|
3555 | 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
|
---|
3556 | 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
|
---|
3557 | 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
|
---|
3558 | 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
|
---|
3559 | 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
|
---|
3560 | 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
|
---|
3561 | 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
|
---|
3562 | 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
|
---|
3563 | 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
|
---|
3564 | 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
|
---|
3565 | 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
|
---|
3566 | 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
|
---|
3567 | 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
|
---|
3568 | 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
|
---|
3569 | 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
|
---|
3570 | 24347096U, 0U
|
---|
3571 |
|
---|
3572 | #if 0
|
---|
3573 | /* The following are the values for 16-bit tables - these work fine for the
|
---|
3574 | * 8-bit conversions but produce very slightly larger errors in the 16-bit
|
---|
3575 | * log (about 1.2 as opposed to 0.7 absolute error in the final value). To
|
---|
3576 | * use these all the shifts below must be adjusted appropriately.
|
---|
3577 | */
|
---|
3578 | 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
|
---|
3579 | 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
|
---|
3580 | 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
|
---|
3581 | 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
|
---|
3582 | 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
|
---|
3583 | 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
|
---|
3584 | 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
|
---|
3585 | 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
|
---|
3586 | 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
|
---|
3587 | 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
|
---|
3588 | 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
|
---|
3589 | 1119, 744, 372
|
---|
3590 | #endif
|
---|
3591 | };
|
---|
3592 |
|
---|
3593 | static png_int_32
|
---|
3594 | png_log8bit(unsigned int x)
|
---|
3595 | {
|
---|
3596 | unsigned int lg2 = 0;
|
---|
3597 | /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
|
---|
3598 | * because the log is actually negate that means adding 1. The final
|
---|
3599 | * returned value thus has the range 0 (for 255 input) to 7.994 (for 1
|
---|
3600 | * input), return -1 for the overflow (log 0) case, - so the result is
|
---|
3601 | * always at most 19 bits.
|
---|
3602 | */
|
---|
3603 | if ((x &= 0xff) == 0)
|
---|
3604 | return -1;
|
---|
3605 |
|
---|
3606 | if ((x & 0xf0) == 0)
|
---|
3607 | lg2 = 4, x <<= 4;
|
---|
3608 |
|
---|
3609 | if ((x & 0xc0) == 0)
|
---|
3610 | lg2 += 2, x <<= 2;
|
---|
3611 |
|
---|
3612 | if ((x & 0x80) == 0)
|
---|
3613 | lg2 += 1, x <<= 1;
|
---|
3614 |
|
---|
3615 | /* result is at most 19 bits, so this cast is safe: */
|
---|
3616 | return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
|
---|
3617 | }
|
---|
3618 |
|
---|
3619 | /* The above gives exact (to 16 binary places) log2 values for 8-bit images,
|
---|
3620 | * for 16-bit images we use the most significant 8 bits of the 16-bit value to
|
---|
3621 | * get an approximation then multiply the approximation by a correction factor
|
---|
3622 | * determined by the remaining up to 8 bits. This requires an additional step
|
---|
3623 | * in the 16-bit case.
|
---|
3624 | *
|
---|
3625 | * We want log2(value/65535), we have log2(v'/255), where:
|
---|
3626 | *
|
---|
3627 | * value = v' * 256 + v''
|
---|
3628 | * = v' * f
|
---|
3629 | *
|
---|
3630 | * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
|
---|
3631 | * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
|
---|
3632 | * than 258. The final factor also needs to correct for the fact that our 8-bit
|
---|
3633 | * value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
|
---|
3634 | *
|
---|
3635 | * This gives a final formula using a calculated value 'x' which is value/v' and
|
---|
3636 | * scaling by 65536 to match the above table:
|
---|
3637 | *
|
---|
3638 | * log2(x/257) * 65536
|
---|
3639 | *
|
---|
3640 | * Since these numbers are so close to '1' we can use simple linear
|
---|
3641 | * interpolation between the two end values 256/257 (result -368.61) and 258/257
|
---|
3642 | * (result 367.179). The values used below are scaled by a further 64 to give
|
---|
3643 | * 16-bit precision in the interpolation:
|
---|
3644 | *
|
---|
3645 | * Start (256): -23591
|
---|
3646 | * Zero (257): 0
|
---|
3647 | * End (258): 23499
|
---|
3648 | */
|
---|
3649 | #ifdef PNG_16BIT_SUPPORTED
|
---|
3650 | static png_int_32
|
---|
3651 | png_log16bit(png_uint_32 x)
|
---|
3652 | {
|
---|
3653 | unsigned int lg2 = 0;
|
---|
3654 |
|
---|
3655 | /* As above, but now the input has 16 bits. */
|
---|
3656 | if ((x &= 0xffff) == 0)
|
---|
3657 | return -1;
|
---|
3658 |
|
---|
3659 | if ((x & 0xff00) == 0)
|
---|
3660 | lg2 = 8, x <<= 8;
|
---|
3661 |
|
---|
3662 | if ((x & 0xf000) == 0)
|
---|
3663 | lg2 += 4, x <<= 4;
|
---|
3664 |
|
---|
3665 | if ((x & 0xc000) == 0)
|
---|
3666 | lg2 += 2, x <<= 2;
|
---|
3667 |
|
---|
3668 | if ((x & 0x8000) == 0)
|
---|
3669 | lg2 += 1, x <<= 1;
|
---|
3670 |
|
---|
3671 | /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
|
---|
3672 | * value.
|
---|
3673 | */
|
---|
3674 | lg2 <<= 28;
|
---|
3675 | lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
|
---|
3676 |
|
---|
3677 | /* Now we need to interpolate the factor, this requires a division by the top
|
---|
3678 | * 8 bits. Do this with maximum precision.
|
---|
3679 | */
|
---|
3680 | x = ((x << 16) + (x >> 9)) / (x >> 8);
|
---|
3681 |
|
---|
3682 | /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
|
---|
3683 | * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
|
---|
3684 | * 16 bits to interpolate to get the low bits of the result. Round the
|
---|
3685 | * answer. Note that the end point values are scaled by 64 to retain overall
|
---|
3686 | * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
|
---|
3687 | * the overall scaling by 6-12. Round at every step.
|
---|
3688 | */
|
---|
3689 | x -= 1U << 24;
|
---|
3690 |
|
---|
3691 | if (x <= 65536U) /* <= '257' */
|
---|
3692 | lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
|
---|
3693 |
|
---|
3694 | else
|
---|
3695 | lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
|
---|
3696 |
|
---|
3697 | /* Safe, because the result can't have more than 20 bits: */
|
---|
3698 | return (png_int_32)((lg2 + 2048) >> 12);
|
---|
3699 | }
|
---|
3700 | #endif /* 16BIT */
|
---|
3701 |
|
---|
3702 | /* The 'exp()' case must invert the above, taking a 20-bit fixed point
|
---|
3703 | * logarithmic value and returning a 16 or 8-bit number as appropriate. In
|
---|
3704 | * each case only the low 16 bits are relevant - the fraction - since the
|
---|
3705 | * integer bits (the top 4) simply determine a shift.
|
---|
3706 | *
|
---|
3707 | * The worst case is the 16-bit distinction between 65535 and 65534. This
|
---|
3708 | * requires perhaps spurious accuracy in the decoding of the logarithm to
|
---|
3709 | * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
|
---|
3710 | * of getting this accuracy in practice.
|
---|
3711 | *
|
---|
3712 | * To deal with this the following exp() function works out the exponent of the
|
---|
3713 | * fractional part of the logarithm by using an accurate 32-bit value from the
|
---|
3714 | * top four fractional bits then multiplying in the remaining bits.
|
---|
3715 | */
|
---|
3716 | static const png_uint_32
|
---|
3717 | png_32bit_exp[16] =
|
---|
3718 | {
|
---|
3719 | /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
|
---|
3720 | 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
|
---|
3721 | 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
|
---|
3722 | 2553802834U, 2445529972U, 2341847524U, 2242560872U
|
---|
3723 | };
|
---|
3724 |
|
---|
3725 | /* Adjustment table; provided to explain the numbers in the code below. */
|
---|
3726 | #if 0
|
---|
3727 | for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
|
---|
3728 | 11 44937.64284865548751208448
|
---|
3729 | 10 45180.98734845585101160448
|
---|
3730 | 9 45303.31936980687359311872
|
---|
3731 | 8 45364.65110595323018870784
|
---|
3732 | 7 45395.35850361789624614912
|
---|
3733 | 6 45410.72259715102037508096
|
---|
3734 | 5 45418.40724413220722311168
|
---|
3735 | 4 45422.25021786898173001728
|
---|
3736 | 3 45424.17186732298419044352
|
---|
3737 | 2 45425.13273269940811464704
|
---|
3738 | 1 45425.61317555035558641664
|
---|
3739 | 0 45425.85339951654943850496
|
---|
3740 | #endif
|
---|
3741 |
|
---|
3742 | static png_uint_32
|
---|
3743 | png_exp(png_fixed_point x)
|
---|
3744 | {
|
---|
3745 | if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
|
---|
3746 | {
|
---|
3747 | /* Obtain a 4-bit approximation */
|
---|
3748 | png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f];
|
---|
3749 |
|
---|
3750 | /* Incorporate the low 12 bits - these decrease the returned value by
|
---|
3751 | * multiplying by a number less than 1 if the bit is set. The multiplier
|
---|
3752 | * is determined by the above table and the shift. Notice that the values
|
---|
3753 | * converge on 45426 and this is used to allow linear interpolation of the
|
---|
3754 | * low bits.
|
---|
3755 | */
|
---|
3756 | if (x & 0x800)
|
---|
3757 | e -= (((e >> 16) * 44938U) + 16U) >> 5;
|
---|
3758 |
|
---|
3759 | if (x & 0x400)
|
---|
3760 | e -= (((e >> 16) * 45181U) + 32U) >> 6;
|
---|
3761 |
|
---|
3762 | if (x & 0x200)
|
---|
3763 | e -= (((e >> 16) * 45303U) + 64U) >> 7;
|
---|
3764 |
|
---|
3765 | if (x & 0x100)
|
---|
3766 | e -= (((e >> 16) * 45365U) + 128U) >> 8;
|
---|
3767 |
|
---|
3768 | if (x & 0x080)
|
---|
3769 | e -= (((e >> 16) * 45395U) + 256U) >> 9;
|
---|
3770 |
|
---|
3771 | if (x & 0x040)
|
---|
3772 | e -= (((e >> 16) * 45410U) + 512U) >> 10;
|
---|
3773 |
|
---|
3774 | /* And handle the low 6 bits in a single block. */
|
---|
3775 | e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
|
---|
3776 |
|
---|
3777 | /* Handle the upper bits of x. */
|
---|
3778 | e >>= x >> 16;
|
---|
3779 | return e;
|
---|
3780 | }
|
---|
3781 |
|
---|
3782 | /* Check for overflow */
|
---|
3783 | if (x <= 0)
|
---|
3784 | return png_32bit_exp[0];
|
---|
3785 |
|
---|
3786 | /* Else underflow */
|
---|
3787 | return 0;
|
---|
3788 | }
|
---|
3789 |
|
---|
3790 | static png_byte
|
---|
3791 | png_exp8bit(png_fixed_point lg2)
|
---|
3792 | {
|
---|
3793 | /* Get a 32-bit value: */
|
---|
3794 | png_uint_32 x = png_exp(lg2);
|
---|
3795 |
|
---|
3796 | /* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
|
---|
3797 | * second, rounding, step can't overflow because of the first, subtraction,
|
---|
3798 | * step.
|
---|
3799 | */
|
---|
3800 | x -= x >> 8;
|
---|
3801 | return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff);
|
---|
3802 | }
|
---|
3803 |
|
---|
3804 | #ifdef PNG_16BIT_SUPPORTED
|
---|
3805 | static png_uint_16
|
---|
3806 | png_exp16bit(png_fixed_point lg2)
|
---|
3807 | {
|
---|
3808 | /* Get a 32-bit value: */
|
---|
3809 | png_uint_32 x = png_exp(lg2);
|
---|
3810 |
|
---|
3811 | /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
|
---|
3812 | x -= x >> 16;
|
---|
3813 | return (png_uint_16)((x + 32767U) >> 16);
|
---|
3814 | }
|
---|
3815 | #endif /* 16BIT */
|
---|
3816 | #endif /* FLOATING_ARITHMETIC */
|
---|
3817 |
|
---|
3818 | png_byte
|
---|
3819 | png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
|
---|
3820 | {
|
---|
3821 | if (value > 0 && value < 255)
|
---|
3822 | {
|
---|
3823 | # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3824 | /* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
|
---|
3825 | * convert this to a floating point value. This includes values that
|
---|
3826 | * would overflow if 'value' were to be converted to 'int'.
|
---|
3827 | *
|
---|
3828 | * Apparently GCC, however, does an intermediate conversion to (int)
|
---|
3829 | * on some (ARM) but not all (x86) platforms, possibly because of
|
---|
3830 | * hardware FP limitations. (E.g. if the hardware conversion always
|
---|
3831 | * assumes the integer register contains a signed value.) This results
|
---|
3832 | * in ANSI-C undefined behavior for large values.
|
---|
3833 | *
|
---|
3834 | * Other implementations on the same machine might actually be ANSI-C90
|
---|
3835 | * conformant and therefore compile spurious extra code for the large
|
---|
3836 | * values.
|
---|
3837 | *
|
---|
3838 | * We can be reasonably sure that an unsigned to float conversion
|
---|
3839 | * won't be faster than an int to float one. Therefore this code
|
---|
3840 | * assumes responsibility for the undefined behavior, which it knows
|
---|
3841 | * can't happen because of the check above.
|
---|
3842 | *
|
---|
3843 | * Note the argument to this routine is an (unsigned int) because, on
|
---|
3844 | * 16-bit platforms, it is assigned a value which might be out of
|
---|
3845 | * range for an (int); that would result in undefined behavior in the
|
---|
3846 | * caller if the *argument* ('value') were to be declared (int).
|
---|
3847 | */
|
---|
3848 | double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
|
---|
3849 | return (png_byte)r;
|
---|
3850 | # else
|
---|
3851 | png_int_32 lg2 = png_log8bit(value);
|
---|
3852 | png_fixed_point res;
|
---|
3853 |
|
---|
3854 | if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
|
---|
3855 | return png_exp8bit(res);
|
---|
3856 |
|
---|
3857 | /* Overflow. */
|
---|
3858 | value = 0;
|
---|
3859 | # endif
|
---|
3860 | }
|
---|
3861 |
|
---|
3862 | return (png_byte)(value & 0xff);
|
---|
3863 | }
|
---|
3864 |
|
---|
3865 | #ifdef PNG_16BIT_SUPPORTED
|
---|
3866 | png_uint_16
|
---|
3867 | png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
|
---|
3868 | {
|
---|
3869 | if (value > 0 && value < 65535)
|
---|
3870 | {
|
---|
3871 | # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3872 | /* The same (unsigned int)->(double) constraints apply here as above,
|
---|
3873 | * however in this case the (unsigned int) to (int) conversion can
|
---|
3874 | * overflow on an ANSI-C90 compliant system so the cast needs to ensure
|
---|
3875 | * that this is not possible.
|
---|
3876 | */
|
---|
3877 | double r = floor(65535*pow((png_int_32)value/65535.,
|
---|
3878 | gamma_val*.00001)+.5);
|
---|
3879 | return (png_uint_16)r;
|
---|
3880 | # else
|
---|
3881 | png_int_32 lg2 = png_log16bit(value);
|
---|
3882 | png_fixed_point res;
|
---|
3883 |
|
---|
3884 | if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
|
---|
3885 | return png_exp16bit(res);
|
---|
3886 |
|
---|
3887 | /* Overflow. */
|
---|
3888 | value = 0;
|
---|
3889 | # endif
|
---|
3890 | }
|
---|
3891 |
|
---|
3892 | return (png_uint_16)value;
|
---|
3893 | }
|
---|
3894 | #endif /* 16BIT */
|
---|
3895 |
|
---|
3896 | /* This does the right thing based on the bit_depth field of the
|
---|
3897 | * png_struct, interpreting values as 8-bit or 16-bit. While the result
|
---|
3898 | * is nominally a 16-bit value if bit depth is 8 then the result is
|
---|
3899 | * 8-bit (as are the arguments.)
|
---|
3900 | */
|
---|
3901 | png_uint_16 /* PRIVATE */
|
---|
3902 | png_gamma_correct(png_structrp png_ptr, unsigned int value,
|
---|
3903 | png_fixed_point gamma_val)
|
---|
3904 | {
|
---|
3905 | if (png_ptr->bit_depth == 8)
|
---|
3906 | return png_gamma_8bit_correct(value, gamma_val);
|
---|
3907 |
|
---|
3908 | #ifdef PNG_16BIT_SUPPORTED
|
---|
3909 | else
|
---|
3910 | return png_gamma_16bit_correct(value, gamma_val);
|
---|
3911 | #else
|
---|
3912 | /* should not reach this */
|
---|
3913 | return 0;
|
---|
3914 | #endif /* 16BIT */
|
---|
3915 | }
|
---|
3916 |
|
---|
3917 | #ifdef PNG_16BIT_SUPPORTED
|
---|
3918 | /* Internal function to build a single 16-bit table - the table consists of
|
---|
3919 | * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
|
---|
3920 | * to shift the input values right (or 16-number_of_signifiant_bits).
|
---|
3921 | *
|
---|
3922 | * The caller is responsible for ensuring that the table gets cleaned up on
|
---|
3923 | * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
|
---|
3924 | * should be somewhere that will be cleaned.
|
---|
3925 | */
|
---|
3926 | static void
|
---|
3927 | png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
|
---|
3928 | unsigned int shift, png_fixed_point gamma_val)
|
---|
3929 | {
|
---|
3930 | /* Various values derived from 'shift': */
|
---|
3931 | unsigned int num = 1U << (8U - shift);
|
---|
3932 | #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3933 | /* CSE the division and work round wacky GCC warnings (see the comments
|
---|
3934 | * in png_gamma_8bit_correct for where these come from.)
|
---|
3935 | */
|
---|
3936 | double fmax = 1.0 / (((png_int_32)1 << (16U - shift)) - 1);
|
---|
3937 | #endif
|
---|
3938 | unsigned int max = (1U << (16U - shift)) - 1U;
|
---|
3939 | unsigned int max_by_2 = 1U << (15U - shift);
|
---|
3940 | unsigned int i;
|
---|
3941 |
|
---|
3942 | png_uint_16pp table = *ptable =
|
---|
3943 | (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
|
---|
3944 |
|
---|
3945 | for (i = 0; i < num; i++)
|
---|
3946 | {
|
---|
3947 | png_uint_16p sub_table = table[i] =
|
---|
3948 | (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
|
---|
3949 |
|
---|
3950 | /* The 'threshold' test is repeated here because it can arise for one of
|
---|
3951 | * the 16-bit tables even if the others don't hit it.
|
---|
3952 | */
|
---|
3953 | if (png_gamma_significant(gamma_val) != 0)
|
---|
3954 | {
|
---|
3955 | /* The old code would overflow at the end and this would cause the
|
---|
3956 | * 'pow' function to return a result >1, resulting in an
|
---|
3957 | * arithmetic error. This code follows the spec exactly; ig is
|
---|
3958 | * the recovered input sample, it always has 8-16 bits.
|
---|
3959 | *
|
---|
3960 | * We want input * 65535/max, rounded, the arithmetic fits in 32
|
---|
3961 | * bits (unsigned) so long as max <= 32767.
|
---|
3962 | */
|
---|
3963 | unsigned int j;
|
---|
3964 | for (j = 0; j < 256; j++)
|
---|
3965 | {
|
---|
3966 | png_uint_32 ig = (j << (8-shift)) + i;
|
---|
3967 | # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
---|
3968 | /* Inline the 'max' scaling operation: */
|
---|
3969 | /* See png_gamma_8bit_correct for why the cast to (int) is
|
---|
3970 | * required here.
|
---|
3971 | */
|
---|
3972 | double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
|
---|
3973 | sub_table[j] = (png_uint_16)d;
|
---|
3974 | # else
|
---|
3975 | if (shift != 0)
|
---|
3976 | ig = (ig * 65535U + max_by_2)/max;
|
---|
3977 |
|
---|
3978 | sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
|
---|
3979 | # endif
|
---|
3980 | }
|
---|
3981 | }
|
---|
3982 | else
|
---|
3983 | {
|
---|
3984 | /* We must still build a table, but do it the fast way. */
|
---|
3985 | unsigned int j;
|
---|
3986 |
|
---|
3987 | for (j = 0; j < 256; j++)
|
---|
3988 | {
|
---|
3989 | png_uint_32 ig = (j << (8-shift)) + i;
|
---|
3990 |
|
---|
3991 | if (shift != 0)
|
---|
3992 | ig = (ig * 65535U + max_by_2)/max;
|
---|
3993 |
|
---|
3994 | sub_table[j] = (png_uint_16)ig;
|
---|
3995 | }
|
---|
3996 | }
|
---|
3997 | }
|
---|
3998 | }
|
---|
3999 |
|
---|
4000 | /* NOTE: this function expects the *inverse* of the overall gamma transformation
|
---|
4001 | * required.
|
---|
4002 | */
|
---|
4003 | static void
|
---|
4004 | png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
|
---|
4005 | unsigned int shift, png_fixed_point gamma_val)
|
---|
4006 | {
|
---|
4007 | unsigned int num = 1U << (8U - shift);
|
---|
4008 | unsigned int max = (1U << (16U - shift))-1U;
|
---|
4009 | unsigned int i;
|
---|
4010 | png_uint_32 last;
|
---|
4011 |
|
---|
4012 | png_uint_16pp table = *ptable =
|
---|
4013 | (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
|
---|
4014 |
|
---|
4015 | /* 'num' is the number of tables and also the number of low bits of low
|
---|
4016 | * bits of the input 16-bit value used to select a table. Each table is
|
---|
4017 | * itself indexed by the high 8 bits of the value.
|
---|
4018 | */
|
---|
4019 | for (i = 0; i < num; i++)
|
---|
4020 | table[i] = (png_uint_16p)png_malloc(png_ptr,
|
---|
4021 | 256 * (sizeof (png_uint_16)));
|
---|
4022 |
|
---|
4023 | /* 'gamma_val' is set to the reciprocal of the value calculated above, so
|
---|
4024 | * pow(out,g) is an *input* value. 'last' is the last input value set.
|
---|
4025 | *
|
---|
4026 | * In the loop 'i' is used to find output values. Since the output is
|
---|
4027 | * 8-bit there are only 256 possible values. The tables are set up to
|
---|
4028 | * select the closest possible output value for each input by finding
|
---|
4029 | * the input value at the boundary between each pair of output values
|
---|
4030 | * and filling the table up to that boundary with the lower output
|
---|
4031 | * value.
|
---|
4032 | *
|
---|
4033 | * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
|
---|
4034 | * values the code below uses a 16-bit value in i; the values start at
|
---|
4035 | * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
|
---|
4036 | * entries are filled with 255). Start i at 128 and fill all 'last'
|
---|
4037 | * table entries <= 'max'
|
---|
4038 | */
|
---|
4039 | last = 0;
|
---|
4040 | for (i = 0; i < 255; ++i) /* 8-bit output value */
|
---|
4041 | {
|
---|
4042 | /* Find the corresponding maximum input value */
|
---|
4043 | png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
|
---|
4044 |
|
---|
4045 | /* Find the boundary value in 16 bits: */
|
---|
4046 | png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
|
---|
4047 |
|
---|
4048 | /* Adjust (round) to (16-shift) bits: */
|
---|
4049 | bound = (bound * max + 32768U)/65535U + 1U;
|
---|
4050 |
|
---|
4051 | while (last < bound)
|
---|
4052 | {
|
---|
4053 | table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
|
---|
4054 | last++;
|
---|
4055 | }
|
---|
4056 | }
|
---|
4057 |
|
---|
4058 | /* And fill in the final entries. */
|
---|
4059 | while (last < (num << 8))
|
---|
4060 | {
|
---|
4061 | table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
|
---|
4062 | last++;
|
---|
4063 | }
|
---|
4064 | }
|
---|
4065 | #endif /* 16BIT */
|
---|
4066 |
|
---|
4067 | /* Build a single 8-bit table: same as the 16-bit case but much simpler (and
|
---|
4068 | * typically much faster). Note that libpng currently does no sBIT processing
|
---|
4069 | * (apparently contrary to the spec) so a 256-entry table is always generated.
|
---|
4070 | */
|
---|
4071 | static void
|
---|
4072 | png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
|
---|
4073 | png_fixed_point gamma_val)
|
---|
4074 | {
|
---|
4075 | unsigned int i;
|
---|
4076 | png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
|
---|
4077 |
|
---|
4078 | if (png_gamma_significant(gamma_val) != 0)
|
---|
4079 | for (i=0; i<256; i++)
|
---|
4080 | table[i] = png_gamma_8bit_correct(i, gamma_val);
|
---|
4081 |
|
---|
4082 | else
|
---|
4083 | for (i=0; i<256; ++i)
|
---|
4084 | table[i] = (png_byte)(i & 0xff);
|
---|
4085 | }
|
---|
4086 |
|
---|
4087 | /* Used from png_read_destroy and below to release the memory used by the gamma
|
---|
4088 | * tables.
|
---|
4089 | */
|
---|
4090 | void /* PRIVATE */
|
---|
4091 | png_destroy_gamma_table(png_structrp png_ptr)
|
---|
4092 | {
|
---|
4093 | png_free(png_ptr, png_ptr->gamma_table);
|
---|
4094 | png_ptr->gamma_table = NULL;
|
---|
4095 |
|
---|
4096 | #ifdef PNG_16BIT_SUPPORTED
|
---|
4097 | if (png_ptr->gamma_16_table != NULL)
|
---|
4098 | {
|
---|
4099 | int i;
|
---|
4100 | int istop = (1 << (8 - png_ptr->gamma_shift));
|
---|
4101 | for (i = 0; i < istop; i++)
|
---|
4102 | {
|
---|
4103 | png_free(png_ptr, png_ptr->gamma_16_table[i]);
|
---|
4104 | }
|
---|
4105 | png_free(png_ptr, png_ptr->gamma_16_table);
|
---|
4106 | png_ptr->gamma_16_table = NULL;
|
---|
4107 | }
|
---|
4108 | #endif /* 16BIT */
|
---|
4109 |
|
---|
4110 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
---|
4111 | defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
---|
4112 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
---|
4113 | png_free(png_ptr, png_ptr->gamma_from_1);
|
---|
4114 | png_ptr->gamma_from_1 = NULL;
|
---|
4115 | png_free(png_ptr, png_ptr->gamma_to_1);
|
---|
4116 | png_ptr->gamma_to_1 = NULL;
|
---|
4117 |
|
---|
4118 | #ifdef PNG_16BIT_SUPPORTED
|
---|
4119 | if (png_ptr->gamma_16_from_1 != NULL)
|
---|
4120 | {
|
---|
4121 | int i;
|
---|
4122 | int istop = (1 << (8 - png_ptr->gamma_shift));
|
---|
4123 | for (i = 0; i < istop; i++)
|
---|
4124 | {
|
---|
4125 | png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
|
---|
4126 | }
|
---|
4127 | png_free(png_ptr, png_ptr->gamma_16_from_1);
|
---|
4128 | png_ptr->gamma_16_from_1 = NULL;
|
---|
4129 | }
|
---|
4130 | if (png_ptr->gamma_16_to_1 != NULL)
|
---|
4131 | {
|
---|
4132 | int i;
|
---|
4133 | int istop = (1 << (8 - png_ptr->gamma_shift));
|
---|
4134 | for (i = 0; i < istop; i++)
|
---|
4135 | {
|
---|
4136 | png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
|
---|
4137 | }
|
---|
4138 | png_free(png_ptr, png_ptr->gamma_16_to_1);
|
---|
4139 | png_ptr->gamma_16_to_1 = NULL;
|
---|
4140 | }
|
---|
4141 | #endif /* 16BIT */
|
---|
4142 | #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
---|
4143 | }
|
---|
4144 |
|
---|
4145 | /* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
|
---|
4146 | * tables, we don't make a full table if we are reducing to 8-bit in
|
---|
4147 | * the future. Note also how the gamma_16 tables are segmented so that
|
---|
4148 | * we don't need to allocate > 64K chunks for a full 16-bit table.
|
---|
4149 | */
|
---|
4150 | void /* PRIVATE */
|
---|
4151 | png_build_gamma_table(png_structrp png_ptr, int bit_depth)
|
---|
4152 | {
|
---|
4153 | png_debug(1, "in png_build_gamma_table");
|
---|
4154 |
|
---|
4155 | /* Remove any existing table; this copes with multiple calls to
|
---|
4156 | * png_read_update_info. The warning is because building the gamma tables
|
---|
4157 | * multiple times is a performance hit - it's harmless but the ability to
|
---|
4158 | * call png_read_update_info() multiple times is new in 1.5.6 so it seems
|
---|
4159 | * sensible to warn if the app introduces such a hit.
|
---|
4160 | */
|
---|
4161 | if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
|
---|
4162 | {
|
---|
4163 | png_warning(png_ptr, "gamma table being rebuilt");
|
---|
4164 | png_destroy_gamma_table(png_ptr);
|
---|
4165 | }
|
---|
4166 |
|
---|
4167 | if (bit_depth <= 8)
|
---|
4168 | {
|
---|
4169 | png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
|
---|
4170 | png_ptr->screen_gamma > 0 ?
|
---|
4171 | png_reciprocal2(png_ptr->colorspace.gamma,
|
---|
4172 | png_ptr->screen_gamma) : PNG_FP_1);
|
---|
4173 |
|
---|
4174 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
---|
4175 | defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
---|
4176 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
---|
4177 | if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
|
---|
4178 | {
|
---|
4179 | png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
|
---|
4180 | png_reciprocal(png_ptr->colorspace.gamma));
|
---|
4181 |
|
---|
4182 | png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
|
---|
4183 | png_ptr->screen_gamma > 0 ?
|
---|
4184 | png_reciprocal(png_ptr->screen_gamma) :
|
---|
4185 | png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
|
---|
4186 | }
|
---|
4187 | #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
---|
4188 | }
|
---|
4189 | #ifdef PNG_16BIT_SUPPORTED
|
---|
4190 | else
|
---|
4191 | {
|
---|
4192 | png_byte shift, sig_bit;
|
---|
4193 |
|
---|
4194 | if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
|
---|
4195 | {
|
---|
4196 | sig_bit = png_ptr->sig_bit.red;
|
---|
4197 |
|
---|
4198 | if (png_ptr->sig_bit.green > sig_bit)
|
---|
4199 | sig_bit = png_ptr->sig_bit.green;
|
---|
4200 |
|
---|
4201 | if (png_ptr->sig_bit.blue > sig_bit)
|
---|
4202 | sig_bit = png_ptr->sig_bit.blue;
|
---|
4203 | }
|
---|
4204 | else
|
---|
4205 | sig_bit = png_ptr->sig_bit.gray;
|
---|
4206 |
|
---|
4207 | /* 16-bit gamma code uses this equation:
|
---|
4208 | *
|
---|
4209 | * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
|
---|
4210 | *
|
---|
4211 | * Where 'iv' is the input color value and 'ov' is the output value -
|
---|
4212 | * pow(iv, gamma).
|
---|
4213 | *
|
---|
4214 | * Thus the gamma table consists of up to 256 256-entry tables. The table
|
---|
4215 | * is selected by the (8-gamma_shift) most significant of the low 8 bits
|
---|
4216 | * of the color value then indexed by the upper 8 bits:
|
---|
4217 | *
|
---|
4218 | * table[low bits][high 8 bits]
|
---|
4219 | *
|
---|
4220 | * So the table 'n' corresponds to all those 'iv' of:
|
---|
4221 | *
|
---|
4222 | * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
|
---|
4223 | *
|
---|
4224 | */
|
---|
4225 | if (sig_bit > 0 && sig_bit < 16U)
|
---|
4226 | /* shift == insignificant bits */
|
---|
4227 | shift = (png_byte)((16U - sig_bit) & 0xff);
|
---|
4228 |
|
---|
4229 | else
|
---|
4230 | shift = 0; /* keep all 16 bits */
|
---|
4231 |
|
---|
4232 | if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
|
---|
4233 | {
|
---|
4234 | /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
|
---|
4235 | * the significant bits in the *input* when the output will
|
---|
4236 | * eventually be 8 bits. By default it is 11.
|
---|
4237 | */
|
---|
4238 | if (shift < (16U - PNG_MAX_GAMMA_8))
|
---|
4239 | shift = (16U - PNG_MAX_GAMMA_8);
|
---|
4240 | }
|
---|
4241 |
|
---|
4242 | if (shift > 8U)
|
---|
4243 | shift = 8U; /* Guarantees at least one table! */
|
---|
4244 |
|
---|
4245 | png_ptr->gamma_shift = shift;
|
---|
4246 |
|
---|
4247 | /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
|
---|
4248 | * PNG_COMPOSE). This effectively smashed the background calculation for
|
---|
4249 | * 16-bit output because the 8-bit table assumes the result will be
|
---|
4250 | * reduced to 8 bits.
|
---|
4251 | */
|
---|
4252 | if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
|
---|
4253 | png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
---|
4254 | png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
|
---|
4255 | png_ptr->screen_gamma) : PNG_FP_1);
|
---|
4256 |
|
---|
4257 | else
|
---|
4258 | png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
---|
4259 | png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
|
---|
4260 | png_ptr->screen_gamma) : PNG_FP_1);
|
---|
4261 |
|
---|
4262 | #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
---|
4263 | defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
---|
4264 | defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
---|
4265 | if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
|
---|
4266 | {
|
---|
4267 | png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
|
---|
4268 | png_reciprocal(png_ptr->colorspace.gamma));
|
---|
4269 |
|
---|
4270 | /* Notice that the '16 from 1' table should be full precision, however
|
---|
4271 | * the lookup on this table still uses gamma_shift, so it can't be.
|
---|
4272 | * TODO: fix this.
|
---|
4273 | */
|
---|
4274 | png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
|
---|
4275 | png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
|
---|
4276 | png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
|
---|
4277 | }
|
---|
4278 | #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
---|
4279 | }
|
---|
4280 | #endif /* 16BIT */
|
---|
4281 | }
|
---|
4282 | #endif /* READ_GAMMA */
|
---|
4283 |
|
---|
4284 | /* HARDWARE OR SOFTWARE OPTION SUPPORT */
|
---|
4285 | #ifdef PNG_SET_OPTION_SUPPORTED
|
---|
4286 | int PNGAPI
|
---|
4287 | png_set_option(png_structrp png_ptr, int option, int onoff)
|
---|
4288 | {
|
---|
4289 | if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
|
---|
4290 | (option & 1) == 0)
|
---|
4291 | {
|
---|
4292 | png_uint_32 mask = 3U << option;
|
---|
4293 | png_uint_32 setting = (2U + (onoff != 0)) << option;
|
---|
4294 | png_uint_32 current = png_ptr->options;
|
---|
4295 |
|
---|
4296 | png_ptr->options = (png_uint_32)((current & ~mask) | setting);
|
---|
4297 |
|
---|
4298 | return (int)(current & mask) >> option;
|
---|
4299 | }
|
---|
4300 |
|
---|
4301 | return PNG_OPTION_INVALID;
|
---|
4302 | }
|
---|
4303 | #endif
|
---|
4304 |
|
---|
4305 | /* sRGB support */
|
---|
4306 | #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
|
---|
4307 | defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
|
---|
4308 | /* sRGB conversion tables; these are machine generated with the code in
|
---|
4309 | * contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
|
---|
4310 | * specification (see the article at https://en.wikipedia.org/wiki/SRGB)
|
---|
4311 | * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
|
---|
4312 | * The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
|
---|
4313 | * The inverse (linear to sRGB) table has accuracies as follows:
|
---|
4314 | *
|
---|
4315 | * For all possible (255*65535+1) input values:
|
---|
4316 | *
|
---|
4317 | * error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
|
---|
4318 | *
|
---|
4319 | * For the input values corresponding to the 65536 16-bit values:
|
---|
4320 | *
|
---|
4321 | * error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
|
---|
4322 | *
|
---|
4323 | * In all cases the inexact readings are only off by one.
|
---|
4324 | */
|
---|
4325 |
|
---|
4326 | #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
---|
4327 | /* The convert-to-sRGB table is only currently required for read. */
|
---|
4328 | const png_uint_16 png_sRGB_table[256] =
|
---|
4329 | {
|
---|
4330 | 0,20,40,60,80,99,119,139,
|
---|
4331 | 159,179,199,219,241,264,288,313,
|
---|
4332 | 340,367,396,427,458,491,526,562,
|
---|
4333 | 599,637,677,718,761,805,851,898,
|
---|
4334 | 947,997,1048,1101,1156,1212,1270,1330,
|
---|
4335 | 1391,1453,1517,1583,1651,1720,1790,1863,
|
---|
4336 | 1937,2013,2090,2170,2250,2333,2418,2504,
|
---|
4337 | 2592,2681,2773,2866,2961,3058,3157,3258,
|
---|
4338 | 3360,3464,3570,3678,3788,3900,4014,4129,
|
---|
4339 | 4247,4366,4488,4611,4736,4864,4993,5124,
|
---|
4340 | 5257,5392,5530,5669,5810,5953,6099,6246,
|
---|
4341 | 6395,6547,6700,6856,7014,7174,7335,7500,
|
---|
4342 | 7666,7834,8004,8177,8352,8528,8708,8889,
|
---|
4343 | 9072,9258,9445,9635,9828,10022,10219,10417,
|
---|
4344 | 10619,10822,11028,11235,11446,11658,11873,12090,
|
---|
4345 | 12309,12530,12754,12980,13209,13440,13673,13909,
|
---|
4346 | 14146,14387,14629,14874,15122,15371,15623,15878,
|
---|
4347 | 16135,16394,16656,16920,17187,17456,17727,18001,
|
---|
4348 | 18277,18556,18837,19121,19407,19696,19987,20281,
|
---|
4349 | 20577,20876,21177,21481,21787,22096,22407,22721,
|
---|
4350 | 23038,23357,23678,24002,24329,24658,24990,25325,
|
---|
4351 | 25662,26001,26344,26688,27036,27386,27739,28094,
|
---|
4352 | 28452,28813,29176,29542,29911,30282,30656,31033,
|
---|
4353 | 31412,31794,32179,32567,32957,33350,33745,34143,
|
---|
4354 | 34544,34948,35355,35764,36176,36591,37008,37429,
|
---|
4355 | 37852,38278,38706,39138,39572,40009,40449,40891,
|
---|
4356 | 41337,41785,42236,42690,43147,43606,44069,44534,
|
---|
4357 | 45002,45473,45947,46423,46903,47385,47871,48359,
|
---|
4358 | 48850,49344,49841,50341,50844,51349,51858,52369,
|
---|
4359 | 52884,53401,53921,54445,54971,55500,56032,56567,
|
---|
4360 | 57105,57646,58190,58737,59287,59840,60396,60955,
|
---|
4361 | 61517,62082,62650,63221,63795,64372,64952,65535
|
---|
4362 | };
|
---|
4363 | #endif /* SIMPLIFIED_READ */
|
---|
4364 |
|
---|
4365 | /* The base/delta tables are required for both read and write (but currently
|
---|
4366 | * only the simplified versions.)
|
---|
4367 | */
|
---|
4368 | const png_uint_16 png_sRGB_base[512] =
|
---|
4369 | {
|
---|
4370 | 128,1782,3383,4644,5675,6564,7357,8074,
|
---|
4371 | 8732,9346,9921,10463,10977,11466,11935,12384,
|
---|
4372 | 12816,13233,13634,14024,14402,14769,15125,15473,
|
---|
4373 | 15812,16142,16466,16781,17090,17393,17690,17981,
|
---|
4374 | 18266,18546,18822,19093,19359,19621,19879,20133,
|
---|
4375 | 20383,20630,20873,21113,21349,21583,21813,22041,
|
---|
4376 | 22265,22487,22707,22923,23138,23350,23559,23767,
|
---|
4377 | 23972,24175,24376,24575,24772,24967,25160,25352,
|
---|
4378 | 25542,25730,25916,26101,26284,26465,26645,26823,
|
---|
4379 | 27000,27176,27350,27523,27695,27865,28034,28201,
|
---|
4380 | 28368,28533,28697,28860,29021,29182,29341,29500,
|
---|
4381 | 29657,29813,29969,30123,30276,30429,30580,30730,
|
---|
4382 | 30880,31028,31176,31323,31469,31614,31758,31902,
|
---|
4383 | 32045,32186,32327,32468,32607,32746,32884,33021,
|
---|
4384 | 33158,33294,33429,33564,33697,33831,33963,34095,
|
---|
4385 | 34226,34357,34486,34616,34744,34873,35000,35127,
|
---|
4386 | 35253,35379,35504,35629,35753,35876,35999,36122,
|
---|
4387 | 36244,36365,36486,36606,36726,36845,36964,37083,
|
---|
4388 | 37201,37318,37435,37551,37668,37783,37898,38013,
|
---|
4389 | 38127,38241,38354,38467,38580,38692,38803,38915,
|
---|
4390 | 39026,39136,39246,39356,39465,39574,39682,39790,
|
---|
4391 | 39898,40005,40112,40219,40325,40431,40537,40642,
|
---|
4392 | 40747,40851,40955,41059,41163,41266,41369,41471,
|
---|
4393 | 41573,41675,41777,41878,41979,42079,42179,42279,
|
---|
4394 | 42379,42478,42577,42676,42775,42873,42971,43068,
|
---|
4395 | 43165,43262,43359,43456,43552,43648,43743,43839,
|
---|
4396 | 43934,44028,44123,44217,44311,44405,44499,44592,
|
---|
4397 | 44685,44778,44870,44962,45054,45146,45238,45329,
|
---|
4398 | 45420,45511,45601,45692,45782,45872,45961,46051,
|
---|
4399 | 46140,46229,46318,46406,46494,46583,46670,46758,
|
---|
4400 | 46846,46933,47020,47107,47193,47280,47366,47452,
|
---|
4401 | 47538,47623,47709,47794,47879,47964,48048,48133,
|
---|
4402 | 48217,48301,48385,48468,48552,48635,48718,48801,
|
---|
4403 | 48884,48966,49048,49131,49213,49294,49376,49458,
|
---|
4404 | 49539,49620,49701,49782,49862,49943,50023,50103,
|
---|
4405 | 50183,50263,50342,50422,50501,50580,50659,50738,
|
---|
4406 | 50816,50895,50973,51051,51129,51207,51285,51362,
|
---|
4407 | 51439,51517,51594,51671,51747,51824,51900,51977,
|
---|
4408 | 52053,52129,52205,52280,52356,52432,52507,52582,
|
---|
4409 | 52657,52732,52807,52881,52956,53030,53104,53178,
|
---|
4410 | 53252,53326,53400,53473,53546,53620,53693,53766,
|
---|
4411 | 53839,53911,53984,54056,54129,54201,54273,54345,
|
---|
4412 | 54417,54489,54560,54632,54703,54774,54845,54916,
|
---|
4413 | 54987,55058,55129,55199,55269,55340,55410,55480,
|
---|
4414 | 55550,55620,55689,55759,55828,55898,55967,56036,
|
---|
4415 | 56105,56174,56243,56311,56380,56448,56517,56585,
|
---|
4416 | 56653,56721,56789,56857,56924,56992,57059,57127,
|
---|
4417 | 57194,57261,57328,57395,57462,57529,57595,57662,
|
---|
4418 | 57728,57795,57861,57927,57993,58059,58125,58191,
|
---|
4419 | 58256,58322,58387,58453,58518,58583,58648,58713,
|
---|
4420 | 58778,58843,58908,58972,59037,59101,59165,59230,
|
---|
4421 | 59294,59358,59422,59486,59549,59613,59677,59740,
|
---|
4422 | 59804,59867,59930,59993,60056,60119,60182,60245,
|
---|
4423 | 60308,60370,60433,60495,60558,60620,60682,60744,
|
---|
4424 | 60806,60868,60930,60992,61054,61115,61177,61238,
|
---|
4425 | 61300,61361,61422,61483,61544,61605,61666,61727,
|
---|
4426 | 61788,61848,61909,61969,62030,62090,62150,62211,
|
---|
4427 | 62271,62331,62391,62450,62510,62570,62630,62689,
|
---|
4428 | 62749,62808,62867,62927,62986,63045,63104,63163,
|
---|
4429 | 63222,63281,63340,63398,63457,63515,63574,63632,
|
---|
4430 | 63691,63749,63807,63865,63923,63981,64039,64097,
|
---|
4431 | 64155,64212,64270,64328,64385,64443,64500,64557,
|
---|
4432 | 64614,64672,64729,64786,64843,64900,64956,65013,
|
---|
4433 | 65070,65126,65183,65239,65296,65352,65409,65465
|
---|
4434 | };
|
---|
4435 |
|
---|
4436 | const png_byte png_sRGB_delta[512] =
|
---|
4437 | {
|
---|
4438 | 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
|
---|
4439 | 52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
|
---|
4440 | 35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
|
---|
4441 | 28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
|
---|
4442 | 23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
|
---|
4443 | 21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
|
---|
4444 | 19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
|
---|
4445 | 17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
|
---|
4446 | 16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
|
---|
4447 | 15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
|
---|
4448 | 14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
|
---|
4449 | 13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
|
---|
4450 | 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
|
---|
4451 | 12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
|
---|
4452 | 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
|
---|
4453 | 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
|
---|
4454 | 11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
---|
4455 | 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
---|
4456 | 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
---|
4457 | 10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
---|
4458 | 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
---|
4459 | 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
---|
4460 | 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
---|
4461 | 9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
---|
4462 | 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
---|
4463 | 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
---|
4464 | 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
---|
4465 | 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
---|
4466 | 8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
|
---|
4467 | 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
---|
4468 | 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
---|
4469 | 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
|
---|
4470 | };
|
---|
4471 | #endif /* SIMPLIFIED READ/WRITE sRGB support */
|
---|
4472 |
|
---|
4473 | /* SIMPLIFIED READ/WRITE SUPPORT */
|
---|
4474 | #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
|
---|
4475 | defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
|
---|
4476 | static int
|
---|
4477 | png_image_free_function(png_voidp argument)
|
---|
4478 | {
|
---|
4479 | png_imagep image = png_voidcast(png_imagep, argument);
|
---|
4480 | png_controlp cp = image->opaque;
|
---|
4481 | png_control c;
|
---|
4482 |
|
---|
4483 | /* Double check that we have a png_ptr - it should be impossible to get here
|
---|
4484 | * without one.
|
---|
4485 | */
|
---|
4486 | if (cp->png_ptr == NULL)
|
---|
4487 | return 0;
|
---|
4488 |
|
---|
4489 | /* First free any data held in the control structure. */
|
---|
4490 | # ifdef PNG_STDIO_SUPPORTED
|
---|
4491 | if (cp->owned_file != 0)
|
---|
4492 | {
|
---|
4493 | FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
|
---|
4494 | cp->owned_file = 0;
|
---|
4495 |
|
---|
4496 | /* Ignore errors here. */
|
---|
4497 | if (fp != NULL)
|
---|
4498 | {
|
---|
4499 | cp->png_ptr->io_ptr = NULL;
|
---|
4500 | (void)fclose(fp);
|
---|
4501 | }
|
---|
4502 | }
|
---|
4503 | # endif
|
---|
4504 |
|
---|
4505 | /* Copy the control structure so that the original, allocated, version can be
|
---|
4506 | * safely freed. Notice that a png_error here stops the remainder of the
|
---|
4507 | * cleanup, but this is probably fine because that would indicate bad memory
|
---|
4508 | * problems anyway.
|
---|
4509 | */
|
---|
4510 | c = *cp;
|
---|
4511 | image->opaque = &c;
|
---|
4512 | png_free(c.png_ptr, cp);
|
---|
4513 |
|
---|
4514 | /* Then the structures, calling the correct API. */
|
---|
4515 | if (c.for_write != 0)
|
---|
4516 | {
|
---|
4517 | # ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
|
---|
4518 | png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
|
---|
4519 | # else
|
---|
4520 | png_error(c.png_ptr, "simplified write not supported");
|
---|
4521 | # endif
|
---|
4522 | }
|
---|
4523 | else
|
---|
4524 | {
|
---|
4525 | # ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
---|
4526 | png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
|
---|
4527 | # else
|
---|
4528 | png_error(c.png_ptr, "simplified read not supported");
|
---|
4529 | # endif
|
---|
4530 | }
|
---|
4531 |
|
---|
4532 | /* Success. */
|
---|
4533 | return 1;
|
---|
4534 | }
|
---|
4535 |
|
---|
4536 | void PNGAPI
|
---|
4537 | png_image_free(png_imagep image)
|
---|
4538 | {
|
---|
4539 | /* Safely call the real function, but only if doing so is safe at this point
|
---|
4540 | * (if not inside an error handling context). Otherwise assume
|
---|
4541 | * png_safe_execute will call this API after the return.
|
---|
4542 | */
|
---|
4543 | if (image != NULL && image->opaque != NULL &&
|
---|
4544 | image->opaque->error_buf == NULL)
|
---|
4545 | {
|
---|
4546 | png_image_free_function(image);
|
---|
4547 | image->opaque = NULL;
|
---|
4548 | }
|
---|
4549 | }
|
---|
4550 |
|
---|
4551 | int /* PRIVATE */
|
---|
4552 | png_image_error(png_imagep image, png_const_charp error_message)
|
---|
4553 | {
|
---|
4554 | /* Utility to log an error. */
|
---|
4555 | png_safecat(image->message, (sizeof image->message), 0, error_message);
|
---|
4556 | image->warning_or_error |= PNG_IMAGE_ERROR;
|
---|
4557 | png_image_free(image);
|
---|
4558 | return 0;
|
---|
4559 | }
|
---|
4560 |
|
---|
4561 | #endif /* SIMPLIFIED READ/WRITE */
|
---|
4562 | #endif /* READ || WRITE */
|
---|