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1 /**
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2 * Orthanc - A Lightweight, RESTful DICOM Store
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1900
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3 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
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1513
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4 * Department, University Hospital of Liege, Belgium
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5 *
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6 * This program is free software: you can redistribute it and/or
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7 * modify it under the terms of the GNU General Public License as
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8 * published by the Free Software Foundation, either version 3 of the
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9 * License, or (at your option) any later version.
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10 *
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11 * In addition, as a special exception, the copyright holders of this
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12 * program give permission to link the code of its release with the
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13 * OpenSSL project's "OpenSSL" library (or with modified versions of it
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14 * that use the same license as the "OpenSSL" library), and distribute
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15 * the linked executables. You must obey the GNU General Public License
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16 * in all respects for all of the code used other than "OpenSSL". If you
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17 * modify file(s) with this exception, you may extend this exception to
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18 * your version of the file(s), but you are not obligated to do so. If
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19 * you do not wish to do so, delete this exception statement from your
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20 * version. If you delete this exception statement from all source files
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21 * in the program, then also delete it here.
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22 *
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23 * This program is distributed in the hope that it will be useful, but
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24 * WITHOUT ANY WARRANTY; without even the implied warranty of
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25 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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26 * General Public License for more details.
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27 *
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28 * You should have received a copy of the GNU General Public License
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29 * along with this program. If not, see <http://www.gnu.org/licenses/>.
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30 **/
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31
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32
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33 #include "../PrecompiledHeaders.h"
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34 #include "GzipCompressor.h"
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35
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36 #include <stdio.h>
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37 #include <string.h>
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38 #include <zlib.h>
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39
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40 #include "../OrthancException.h"
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41 #include "../Logging.h"
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42
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43 namespace Orthanc
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44 {
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45 uint64_t GzipCompressor::GuessUncompressedSize(const void* compressed,
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46 size_t compressedSize)
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47 {
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48 /**
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49 * "Is there a way to find out the size of the original file which
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50 * is inside a GZIP file? [...] There is no truly reliable way,
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51 * other than gunzipping the stream. You do not need to save the
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52 * result of the decompression, so you can determine the size by
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53 * simply reading and decoding the entire file without taking up
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54 * space with the decompressed result.
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55 *
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56 * There is an unreliable way to determine the uncompressed size,
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57 * which is to look at the last four bytes of the gzip file, which
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58 * is the uncompressed length of that entry modulo 232 in little
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59 * endian order.
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60 *
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61 * It is unreliable because a) the uncompressed data may be longer
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62 * than 2^32 bytes, and b) the gzip file may consist of multiple
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63 * gzip streams, in which case you would find the length of only
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64 * the last of those streams.
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65 *
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66 * If you are in control of the source of the gzip files, you know
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67 * that they consist of single gzip streams, and you know that
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68 * they are less than 2^32 bytes uncompressed, then and only then
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69 * can you use those last four bytes with confidence."
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70 *
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71 * http://stackoverflow.com/a/9727599/881731
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72 **/
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73
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74 if (compressedSize < 4)
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75 {
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76 throw OrthancException(ErrorCode_BadFileFormat);
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77 }
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78
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79 const uint8_t* p = reinterpret_cast<const uint8_t*>(compressed) + compressedSize - 4;
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80
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81 return ((static_cast<uint32_t>(p[0]) << 0) +
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82 (static_cast<uint32_t>(p[1]) << 8) +
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83 (static_cast<uint32_t>(p[2]) << 16) +
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84 (static_cast<uint32_t>(p[3]) << 24));
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85 }
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86
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87
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88
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89 void GzipCompressor::Compress(std::string& compressed,
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90 const void* uncompressed,
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91 size_t uncompressedSize)
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92 {
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93 uLongf compressedSize = compressBound(uncompressedSize) + 1024 /* security margin */;
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94 if (compressedSize == 0)
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95 {
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96 compressedSize = 1;
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97 }
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98
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99 uint8_t* target;
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100 if (HasPrefixWithUncompressedSize())
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101 {
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102 compressed.resize(compressedSize + sizeof(uint64_t));
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103 target = reinterpret_cast<uint8_t*>(&compressed[0]) + sizeof(uint64_t);
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104 }
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105 else
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106 {
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107 compressed.resize(compressedSize);
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108 target = reinterpret_cast<uint8_t*>(&compressed[0]);
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109 }
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110
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111 z_stream stream;
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112 memset(&stream, 0, sizeof(stream));
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113
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114 stream.next_in = const_cast<Bytef*>(reinterpret_cast<const Bytef*>(uncompressed));
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115 stream.next_out = reinterpret_cast<Bytef*>(target);
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116
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117 stream.avail_in = static_cast<uInt>(uncompressedSize);
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118 stream.avail_out = static_cast<uInt>(compressedSize);
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119
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120 // Ensure no overflow (if the buffer is too large for the current archicture)
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121 if (static_cast<size_t>(stream.avail_in) != uncompressedSize ||
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122 static_cast<size_t>(stream.avail_out) != compressedSize)
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123 {
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124 throw OrthancException(ErrorCode_NotEnoughMemory);
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125 }
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126
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127 // Initialize the compression engine
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128 int error = deflateInit2(&stream,
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129 GetCompressionLevel(),
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130 Z_DEFLATED,
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131 MAX_WBITS + 16, // ask for gzip output
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132 8, // default memory level
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133 Z_DEFAULT_STRATEGY);
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134
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135 if (error != Z_OK)
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136 {
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137 // Cannot initialize zlib
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138 compressed.clear();
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139 throw OrthancException(ErrorCode_InternalError);
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140 }
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141
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142 // Compress the input buffer
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143 error = deflate(&stream, Z_FINISH);
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144
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145 if (error != Z_STREAM_END)
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146 {
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147 deflateEnd(&stream);
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148 compressed.clear();
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149
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150 switch (error)
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151 {
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152 case Z_MEM_ERROR:
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153 throw OrthancException(ErrorCode_NotEnoughMemory);
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154
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155 default:
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156 throw OrthancException(ErrorCode_InternalError);
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157 }
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158 }
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159
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160 size_t size = stream.total_out;
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161
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162 if (deflateEnd(&stream) != Z_OK)
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163 {
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164 throw OrthancException(ErrorCode_InternalError);
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165 }
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166
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167 // The compression was successful
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168 if (HasPrefixWithUncompressedSize())
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169 {
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170 uint64_t s = static_cast<uint64_t>(uncompressedSize);
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171 memcpy(&compressed[0], &s, sizeof(uint64_t));
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172 compressed.resize(size + sizeof(uint64_t));
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173 }
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174 else
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175 {
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176 compressed.resize(size);
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177 }
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178 }
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179
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180
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181 void GzipCompressor::Uncompress(std::string& uncompressed,
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182 const void* compressed,
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183 size_t compressedSize)
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184 {
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185 uint64_t uncompressedSize;
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186 const uint8_t* source = reinterpret_cast<const uint8_t*>(compressed);
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187
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188 if (HasPrefixWithUncompressedSize())
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189 {
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190 uncompressedSize = ReadUncompressedSizePrefix(compressed, compressedSize);
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191 source += sizeof(uint64_t);
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192 compressedSize -= sizeof(uint64_t);
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193 }
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194 else
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195 {
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196 uncompressedSize = GuessUncompressedSize(compressed, compressedSize);
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197 }
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198
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199 try
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200 {
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201 uncompressed.resize(static_cast<size_t>(uncompressedSize));
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202 }
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203 catch (...)
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204 {
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205 throw OrthancException(ErrorCode_NotEnoughMemory);
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206 }
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207
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208 z_stream stream;
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209 memset(&stream, 0, sizeof(stream));
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210
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211 char dummy = '\0'; // zlib does not like NULL output buffers (even if the uncompressed data is empty)
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212 stream.next_in = const_cast<Bytef*>(source);
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213 stream.next_out = reinterpret_cast<Bytef*>(uncompressedSize == 0 ? &dummy : &uncompressed[0]);
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214
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215 stream.avail_in = static_cast<uInt>(compressedSize);
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216 stream.avail_out = static_cast<uInt>(uncompressedSize);
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217
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218 // Ensure no overflow (if the buffer is too large for the current archicture)
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219 if (static_cast<size_t>(stream.avail_in) != compressedSize ||
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220 static_cast<size_t>(stream.avail_out) != uncompressedSize)
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221 {
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222 throw OrthancException(ErrorCode_NotEnoughMemory);
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223 }
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224
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225 // Initialize the compression engine
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226 int error = inflateInit2(&stream,
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227 MAX_WBITS + 16); // this is a gzip input
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228
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229 if (error != Z_OK)
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230 {
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231 // Cannot initialize zlib
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232 uncompressed.clear();
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233 throw OrthancException(ErrorCode_InternalError);
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234 }
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235
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236 // Uncompress the input buffer
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237 error = inflate(&stream, Z_FINISH);
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238
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239 if (error != Z_STREAM_END)
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240 {
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241 inflateEnd(&stream);
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242 uncompressed.clear();
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243
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244 switch (error)
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245 {
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246 case Z_MEM_ERROR:
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247 throw OrthancException(ErrorCode_NotEnoughMemory);
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248
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249 case Z_BUF_ERROR:
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250 case Z_NEED_DICT:
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251 throw OrthancException(ErrorCode_BadFileFormat);
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252
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253 default:
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254 throw OrthancException(ErrorCode_InternalError);
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255 }
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256 }
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257
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258 size_t size = stream.total_out;
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259
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260 if (inflateEnd(&stream) != Z_OK)
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261 {
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262 uncompressed.clear();
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263 throw OrthancException(ErrorCode_InternalError);
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264 }
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265
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266 if (size != uncompressedSize)
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267 {
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268 uncompressed.clear();
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269
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270 // The uncompressed size was not that properly guess, presumably
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271 // because of a file size over 4GB. Should fallback to
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272 // stream-based decompression.
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273 LOG(ERROR) << "The uncompressed size of a gzip-encoded buffer was not properly guessed";
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274 throw OrthancException(ErrorCode_NotImplemented);
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275 }
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276 }
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277 }
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