1 | /* vi: set sw=4 ts=4: */ |
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2 | /* Small bzip2 deflate implementation, by Rob Landley (rob@landley.net). |
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3 | |
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4 | Based on bzip2 decompression code by Julian R Seward (jseward@acm.org), |
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5 | which also acknowledges contributions by Mike Burrows, David Wheeler, |
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6 | Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten, |
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7 | Robert Sedgewick, and Jon L. Bentley. |
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8 | |
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9 | Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
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10 | */ |
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11 | |
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12 | /* |
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13 | Size and speed optimizations by Manuel Novoa III (mjn3@codepoet.org). |
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14 | |
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15 | More efficient reading of Huffman codes, a streamlined read_bunzip() |
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16 | function, and various other tweaks. In (limited) tests, approximately |
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17 | 20% faster than bzcat on x86 and about 10% faster on arm. |
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18 | |
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19 | Note that about 2/3 of the time is spent in read_unzip() reversing |
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20 | the Burrows-Wheeler transformation. Much of that time is delay |
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21 | resulting from cache misses. |
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22 | |
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23 | I would ask that anyone benefiting from this work, especially those |
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24 | using it in commercial products, consider making a donation to my local |
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25 | non-profit hospice organization (www.hospiceacadiana.com) in the name of |
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26 | the woman I loved, Toni W. Hagan, who passed away Feb. 12, 2003. |
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27 | |
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28 | Manuel |
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29 | */ |
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30 | |
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31 | #include "libbb.h" |
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32 | #include "unarchive.h" |
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33 | |
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34 | /* Constants for Huffman coding */ |
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35 | #define MAX_GROUPS 6 |
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36 | #define GROUP_SIZE 50 /* 64 would have been more efficient */ |
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37 | #define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */ |
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38 | #define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */ |
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39 | #define SYMBOL_RUNA 0 |
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40 | #define SYMBOL_RUNB 1 |
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41 | |
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42 | /* Status return values */ |
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43 | #define RETVAL_OK 0 |
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44 | #define RETVAL_LAST_BLOCK (-1) |
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45 | #define RETVAL_NOT_BZIP_DATA (-2) |
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46 | #define RETVAL_UNEXPECTED_INPUT_EOF (-3) |
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47 | #define RETVAL_UNEXPECTED_OUTPUT_EOF (-4) |
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48 | #define RETVAL_DATA_ERROR (-5) |
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49 | #define RETVAL_OUT_OF_MEMORY (-6) |
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50 | #define RETVAL_OBSOLETE_INPUT (-7) |
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51 | |
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52 | /* Other housekeeping constants */ |
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53 | #define IOBUF_SIZE 4096 |
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54 | |
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55 | /* This is what we know about each Huffman coding group */ |
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56 | struct group_data { |
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57 | /* We have an extra slot at the end of limit[] for a sentinal value. */ |
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58 | int limit[MAX_HUFCODE_BITS+1], base[MAX_HUFCODE_BITS], permute[MAX_SYMBOLS]; |
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59 | int minLen, maxLen; |
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60 | }; |
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61 | |
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62 | /* Structure holding all the housekeeping data, including IO buffers and |
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63 | memory that persists between calls to bunzip */ |
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64 | |
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65 | struct bunzip_data { |
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66 | /* State for interrupting output loop */ |
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67 | int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent; |
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68 | |
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69 | /* I/O tracking data (file handles, buffers, positions, etc.) */ |
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70 | int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/; |
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71 | unsigned char *inbuf /*,*outbuf*/; |
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72 | unsigned inbufBitCount, inbufBits; |
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73 | |
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74 | /* The CRC values stored in the block header and calculated from the data */ |
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75 | uint32_t headerCRC, totalCRC, writeCRC; |
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76 | |
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77 | /* Intermediate buffer and its size (in bytes) */ |
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78 | unsigned *dbuf, dbufSize; |
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79 | |
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80 | /* For I/O error handling */ |
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81 | jmp_buf jmpbuf; |
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82 | |
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83 | /* Big things go last (register-relative addressing can be larger for big offsets */ |
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84 | uint32_t crc32Table[256]; |
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85 | unsigned char selectors[32768]; /* nSelectors=15 bits */ |
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86 | struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */ |
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87 | }; |
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88 | /* typedef struct bunzip_data bunzip_data; -- done in .h file */ |
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89 | |
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90 | |
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91 | /* Return the next nnn bits of input. All reads from the compressed input |
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92 | are done through this function. All reads are big endian */ |
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93 | |
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94 | static unsigned get_bits(bunzip_data *bd, char bits_wanted) |
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95 | { |
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96 | unsigned bits = 0; |
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97 | |
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98 | /* If we need to get more data from the byte buffer, do so. (Loop getting |
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99 | one byte at a time to enforce endianness and avoid unaligned access.) */ |
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100 | |
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101 | while (bd->inbufBitCount < bits_wanted) { |
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102 | |
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103 | /* If we need to read more data from file into byte buffer, do so */ |
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104 | |
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105 | if (bd->inbufPos == bd->inbufCount) { |
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106 | /* if "no input fd" case: in_fd == -1, read fails, we jump */ |
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107 | bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE); |
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108 | if (bd->inbufCount <= 0) |
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109 | longjmp(bd->jmpbuf, RETVAL_UNEXPECTED_INPUT_EOF); |
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110 | bd->inbufPos = 0; |
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111 | } |
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112 | |
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113 | /* Avoid 32-bit overflow (dump bit buffer to top of output) */ |
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114 | |
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115 | if (bd->inbufBitCount >= 24) { |
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116 | bits = bd->inbufBits & ((1 << bd->inbufBitCount) - 1); |
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117 | bits_wanted -= bd->inbufBitCount; |
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118 | bits <<= bits_wanted; |
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119 | bd->inbufBitCount = 0; |
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120 | } |
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121 | |
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122 | /* Grab next 8 bits of input from buffer. */ |
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123 | |
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124 | bd->inbufBits = (bd->inbufBits<<8) | bd->inbuf[bd->inbufPos++]; |
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125 | bd->inbufBitCount += 8; |
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126 | } |
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127 | |
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128 | /* Calculate result */ |
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129 | |
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130 | bd->inbufBitCount -= bits_wanted; |
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131 | bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1 << bits_wanted) - 1); |
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132 | |
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133 | return bits; |
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134 | } |
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135 | |
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136 | /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */ |
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137 | |
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138 | static int get_next_block(bunzip_data *bd) |
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139 | { |
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140 | struct group_data *hufGroup; |
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141 | int dbufCount, nextSym, dbufSize, groupCount, *base, *limit, selector, |
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142 | i, j, k, t, runPos, symCount, symTotal, nSelectors, byteCount[256]; |
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143 | unsigned char uc, symToByte[256], mtfSymbol[256], *selectors; |
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144 | unsigned *dbuf, origPtr; |
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145 | |
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146 | dbuf = bd->dbuf; |
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147 | dbufSize = bd->dbufSize; |
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148 | selectors = bd->selectors; |
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149 | |
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150 | /* Reset longjmp I/O error handling */ |
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151 | |
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152 | i = setjmp(bd->jmpbuf); |
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153 | if (i) return i; |
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154 | |
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155 | /* Read in header signature and CRC, then validate signature. |
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156 | (last block signature means CRC is for whole file, return now) */ |
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157 | |
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158 | i = get_bits(bd, 24); |
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159 | j = get_bits(bd, 24); |
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160 | bd->headerCRC = get_bits(bd, 32); |
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161 | if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK; |
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162 | if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA; |
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163 | |
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164 | /* We can add support for blockRandomised if anybody complains. There was |
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165 | some code for this in busybox 1.0.0-pre3, but nobody ever noticed that |
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166 | it didn't actually work. */ |
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167 | |
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168 | if (get_bits(bd, 1)) return RETVAL_OBSOLETE_INPUT; |
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169 | origPtr = get_bits(bd, 24); |
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170 | if (origPtr > dbufSize) return RETVAL_DATA_ERROR; |
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171 | |
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172 | /* mapping table: if some byte values are never used (encoding things |
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173 | like ascii text), the compression code removes the gaps to have fewer |
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174 | symbols to deal with, and writes a sparse bitfield indicating which |
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175 | values were present. We make a translation table to convert the symbols |
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176 | back to the corresponding bytes. */ |
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177 | |
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178 | t = get_bits(bd, 16); |
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179 | symTotal = 0; |
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180 | for (i = 0; i < 16; i++) { |
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181 | if (t & (1 << (15-i))) { |
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182 | k = get_bits(bd, 16); |
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183 | for (j = 0; j < 16; j++) |
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184 | if (k & (1 << (15-j))) |
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185 | symToByte[symTotal++] = (16*i) + j; |
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186 | } |
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187 | } |
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188 | |
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189 | /* How many different Huffman coding groups does this block use? */ |
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190 | |
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191 | groupCount = get_bits(bd, 3); |
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192 | if (groupCount < 2 || groupCount > MAX_GROUPS) |
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193 | return RETVAL_DATA_ERROR; |
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194 | |
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195 | /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding |
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196 | group. Read in the group selector list, which is stored as MTF encoded |
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197 | bit runs. (MTF=Move To Front, as each value is used it's moved to the |
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198 | start of the list.) */ |
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199 | |
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200 | nSelectors = get_bits(bd, 15); |
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201 | if (!nSelectors) return RETVAL_DATA_ERROR; |
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202 | for (i = 0; i < groupCount; i++) mtfSymbol[i] = i; |
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203 | for (i = 0; i < nSelectors; i++) { |
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204 | |
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205 | /* Get next value */ |
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206 | |
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207 | for (j = 0; get_bits(bd, 1); j++) |
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208 | if (j>=groupCount) return RETVAL_DATA_ERROR; |
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209 | |
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210 | /* Decode MTF to get the next selector */ |
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211 | |
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212 | uc = mtfSymbol[j]; |
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213 | for (;j;j--) mtfSymbol[j] = mtfSymbol[j-1]; |
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214 | mtfSymbol[0] = selectors[i] = uc; |
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215 | } |
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216 | |
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217 | /* Read the Huffman coding tables for each group, which code for symTotal |
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218 | literal symbols, plus two run symbols (RUNA, RUNB) */ |
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219 | |
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220 | symCount = symTotal + 2; |
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221 | for (j = 0; j < groupCount; j++) { |
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222 | unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1]; |
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223 | int minLen, maxLen, pp; |
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224 | |
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225 | /* Read Huffman code lengths for each symbol. They're stored in |
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226 | a way similar to mtf; record a starting value for the first symbol, |
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227 | and an offset from the previous value for everys symbol after that. |
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228 | (Subtracting 1 before the loop and then adding it back at the end is |
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229 | an optimization that makes the test inside the loop simpler: symbol |
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230 | length 0 becomes negative, so an unsigned inequality catches it.) */ |
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231 | |
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232 | t = get_bits(bd, 5) - 1; |
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233 | for (i = 0; i < symCount; i++) { |
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234 | for (;;) { |
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235 | if ((unsigned)t > (MAX_HUFCODE_BITS-1)) |
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236 | return RETVAL_DATA_ERROR; |
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237 | |
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238 | /* If first bit is 0, stop. Else second bit indicates whether |
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239 | to increment or decrement the value. Optimization: grab 2 |
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240 | bits and unget the second if the first was 0. */ |
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241 | |
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242 | k = get_bits(bd, 2); |
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243 | if (k < 2) { |
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244 | bd->inbufBitCount++; |
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245 | break; |
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246 | } |
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247 | |
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248 | /* Add one if second bit 1, else subtract 1. Avoids if/else */ |
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249 | |
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250 | t += (((k+1) & 2) - 1); |
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251 | } |
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252 | |
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253 | /* Correct for the initial -1, to get the final symbol length */ |
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254 | |
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255 | length[i] = t + 1; |
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256 | } |
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257 | |
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258 | /* Find largest and smallest lengths in this group */ |
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259 | |
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260 | minLen = maxLen = length[0]; |
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261 | for (i = 1; i < symCount; i++) { |
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262 | if (length[i] > maxLen) maxLen = length[i]; |
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263 | else if (length[i] < minLen) minLen = length[i]; |
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264 | } |
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265 | |
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266 | /* Calculate permute[], base[], and limit[] tables from length[]. |
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267 | * |
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268 | * permute[] is the lookup table for converting Huffman coded symbols |
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269 | * into decoded symbols. base[] is the amount to subtract from the |
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270 | * value of a Huffman symbol of a given length when using permute[]. |
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271 | * |
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272 | * limit[] indicates the largest numerical value a symbol with a given |
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273 | * number of bits can have. This is how the Huffman codes can vary in |
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274 | * length: each code with a value>limit[length] needs another bit. |
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275 | */ |
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276 | |
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277 | hufGroup = bd->groups + j; |
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278 | hufGroup->minLen = minLen; |
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279 | hufGroup->maxLen = maxLen; |
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280 | |
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281 | /* Note that minLen can't be smaller than 1, so we adjust the base |
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282 | and limit array pointers so we're not always wasting the first |
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283 | entry. We do this again when using them (during symbol decoding).*/ |
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284 | |
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285 | base = hufGroup->base - 1; |
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286 | limit = hufGroup->limit - 1; |
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287 | |
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288 | /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */ |
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289 | |
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290 | pp = 0; |
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291 | for (i = minLen; i <= maxLen; i++) { |
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292 | temp[i] = limit[i] = 0; |
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293 | for (t = 0; t < symCount; t++) |
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294 | if (length[t] == i) |
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295 | hufGroup->permute[pp++] = t; |
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296 | } |
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297 | |
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298 | /* Count symbols coded for at each bit length */ |
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299 | |
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300 | for (i = 0; i < symCount; i++) temp[length[i]]++; |
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301 | |
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302 | /* Calculate limit[] (the largest symbol-coding value at each bit |
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303 | * length, which is (previous limit<<1)+symbols at this level), and |
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304 | * base[] (number of symbols to ignore at each bit length, which is |
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305 | * limit minus the cumulative count of symbols coded for already). */ |
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306 | |
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307 | pp = t = 0; |
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308 | for (i = minLen; i < maxLen; i++) { |
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309 | pp += temp[i]; |
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310 | |
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311 | /* We read the largest possible symbol size and then unget bits |
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312 | after determining how many we need, and those extra bits could |
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313 | be set to anything. (They're noise from future symbols.) At |
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314 | each level we're really only interested in the first few bits, |
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315 | so here we set all the trailing to-be-ignored bits to 1 so they |
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316 | don't affect the value>limit[length] comparison. */ |
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317 | |
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318 | limit[i] = (pp << (maxLen - i)) - 1; |
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319 | pp <<= 1; |
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320 | t += temp[i]; |
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321 | base[i+1] = pp - t; |
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322 | } |
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323 | limit[maxLen+1] = INT_MAX; /* Sentinal value for reading next sym. */ |
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324 | limit[maxLen] = pp + temp[maxLen] - 1; |
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325 | base[minLen] = 0; |
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326 | } |
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327 | |
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328 | /* We've finished reading and digesting the block header. Now read this |
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329 | block's Huffman coded symbols from the file and undo the Huffman coding |
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330 | and run length encoding, saving the result into dbuf[dbufCount++]=uc */ |
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331 | |
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332 | /* Initialize symbol occurrence counters and symbol Move To Front table */ |
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333 | |
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334 | for (i = 0; i < 256; i++) { |
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335 | byteCount[i] = 0; |
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336 | mtfSymbol[i] = (unsigned char)i; |
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337 | } |
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338 | |
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339 | /* Loop through compressed symbols. */ |
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340 | |
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341 | runPos = dbufCount = selector = 0; |
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342 | for (;;) { |
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343 | |
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344 | /* fetch next Huffman coding group from list. */ |
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345 | |
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346 | symCount = GROUP_SIZE - 1; |
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347 | if (selector >= nSelectors) return RETVAL_DATA_ERROR; |
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348 | hufGroup = bd->groups + selectors[selector++]; |
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349 | base = hufGroup->base - 1; |
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350 | limit = hufGroup->limit - 1; |
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351 | continue_this_group: |
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352 | |
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353 | /* Read next Huffman-coded symbol. */ |
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354 | |
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355 | /* Note: It is far cheaper to read maxLen bits and back up than it is |
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356 | to read minLen bits and then an additional bit at a time, testing |
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357 | as we go. Because there is a trailing last block (with file CRC), |
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358 | there is no danger of the overread causing an unexpected EOF for a |
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359 | valid compressed file. As a further optimization, we do the read |
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360 | inline (falling back to a call to get_bits if the buffer runs |
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361 | dry). The following (up to got_huff_bits:) is equivalent to |
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362 | j = get_bits(bd, hufGroup->maxLen); |
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363 | */ |
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364 | |
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365 | while (bd->inbufBitCount < hufGroup->maxLen) { |
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366 | if (bd->inbufPos == bd->inbufCount) { |
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367 | j = get_bits(bd, hufGroup->maxLen); |
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368 | goto got_huff_bits; |
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369 | } |
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370 | bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++]; |
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371 | bd->inbufBitCount += 8; |
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372 | }; |
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373 | bd->inbufBitCount -= hufGroup->maxLen; |
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374 | j = (bd->inbufBits >> bd->inbufBitCount) & ((1 << hufGroup->maxLen) - 1); |
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375 | |
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376 | got_huff_bits: |
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377 | |
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378 | /* Figure how how many bits are in next symbol and unget extras */ |
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379 | |
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380 | i = hufGroup->minLen; |
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381 | while (j > limit[i]) ++i; |
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382 | bd->inbufBitCount += (hufGroup->maxLen - i); |
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383 | |
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384 | /* Huffman decode value to get nextSym (with bounds checking) */ |
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385 | |
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386 | if (i > hufGroup->maxLen) |
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387 | return RETVAL_DATA_ERROR; |
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388 | j = (j >> (hufGroup->maxLen - i)) - base[i]; |
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389 | if ((unsigned)j >= MAX_SYMBOLS) |
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390 | return RETVAL_DATA_ERROR; |
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391 | nextSym = hufGroup->permute[j]; |
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392 | |
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393 | /* We have now decoded the symbol, which indicates either a new literal |
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394 | byte, or a repeated run of the most recent literal byte. First, |
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395 | check if nextSym indicates a repeated run, and if so loop collecting |
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396 | how many times to repeat the last literal. */ |
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397 | |
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398 | if ((unsigned)nextSym <= SYMBOL_RUNB) { /* RUNA or RUNB */ |
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399 | |
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400 | /* If this is the start of a new run, zero out counter */ |
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401 | |
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402 | if (!runPos) { |
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403 | runPos = 1; |
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404 | t = 0; |
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405 | } |
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406 | |
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407 | /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at |
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408 | each bit position, add 1 or 2 instead. For example, |
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409 | 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2. |
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410 | You can make any bit pattern that way using 1 less symbol than |
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411 | the basic or 0/1 method (except all bits 0, which would use no |
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412 | symbols, but a run of length 0 doesn't mean anything in this |
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413 | context). Thus space is saved. */ |
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414 | |
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415 | t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ |
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416 | if (runPos < dbufSize) runPos <<= 1; |
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417 | goto end_of_huffman_loop; |
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418 | } |
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419 | |
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420 | /* When we hit the first non-run symbol after a run, we now know |
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421 | how many times to repeat the last literal, so append that many |
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422 | copies to our buffer of decoded symbols (dbuf) now. (The last |
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423 | literal used is the one at the head of the mtfSymbol array.) */ |
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424 | |
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425 | if (runPos) { |
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426 | runPos = 0; |
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427 | if (dbufCount + t >= dbufSize) return RETVAL_DATA_ERROR; |
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428 | |
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429 | uc = symToByte[mtfSymbol[0]]; |
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430 | byteCount[uc] += t; |
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431 | while (t--) dbuf[dbufCount++] = uc; |
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432 | } |
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433 | |
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434 | /* Is this the terminating symbol? */ |
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435 | |
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436 | if (nextSym > symTotal) break; |
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437 | |
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438 | /* At this point, nextSym indicates a new literal character. Subtract |
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439 | one to get the position in the MTF array at which this literal is |
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440 | currently to be found. (Note that the result can't be -1 or 0, |
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441 | because 0 and 1 are RUNA and RUNB. But another instance of the |
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442 | first symbol in the mtf array, position 0, would have been handled |
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443 | as part of a run above. Therefore 1 unused mtf position minus |
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444 | 2 non-literal nextSym values equals -1.) */ |
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445 | |
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446 | if (dbufCount >= dbufSize) return RETVAL_DATA_ERROR; |
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447 | i = nextSym - 1; |
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448 | uc = mtfSymbol[i]; |
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449 | |
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450 | /* Adjust the MTF array. Since we typically expect to move only a |
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451 | * small number of symbols, and are bound by 256 in any case, using |
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452 | * memmove here would typically be bigger and slower due to function |
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453 | * call overhead and other assorted setup costs. */ |
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454 | |
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455 | do { |
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456 | mtfSymbol[i] = mtfSymbol[i-1]; |
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457 | } while (--i); |
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458 | mtfSymbol[0] = uc; |
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459 | uc = symToByte[uc]; |
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460 | |
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461 | /* We have our literal byte. Save it into dbuf. */ |
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462 | |
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463 | byteCount[uc]++; |
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464 | dbuf[dbufCount++] = (unsigned)uc; |
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465 | |
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466 | /* Skip group initialization if we're not done with this group. Done |
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467 | * this way to avoid compiler warning. */ |
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468 | |
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469 | end_of_huffman_loop: |
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470 | if (symCount--) goto continue_this_group; |
---|
471 | } |
---|
472 | |
---|
473 | /* At this point, we've read all the Huffman-coded symbols (and repeated |
---|
474 | runs) for this block from the input stream, and decoded them into the |
---|
475 | intermediate buffer. There are dbufCount many decoded bytes in dbuf[]. |
---|
476 | Now undo the Burrows-Wheeler transform on dbuf. |
---|
477 | See http://dogma.net/markn/articles/bwt/bwt.htm |
---|
478 | */ |
---|
479 | |
---|
480 | /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */ |
---|
481 | |
---|
482 | j = 0; |
---|
483 | for (i = 0; i < 256; i++) { |
---|
484 | k = j + byteCount[i]; |
---|
485 | byteCount[i] = j; |
---|
486 | j = k; |
---|
487 | } |
---|
488 | |
---|
489 | /* Figure out what order dbuf would be in if we sorted it. */ |
---|
490 | |
---|
491 | for (i = 0; i < dbufCount; i++) { |
---|
492 | uc = (unsigned char)(dbuf[i] & 0xff); |
---|
493 | dbuf[byteCount[uc]] |= (i << 8); |
---|
494 | byteCount[uc]++; |
---|
495 | } |
---|
496 | |
---|
497 | /* Decode first byte by hand to initialize "previous" byte. Note that it |
---|
498 | doesn't get output, and if the first three characters are identical |
---|
499 | it doesn't qualify as a run (hence writeRunCountdown=5). */ |
---|
500 | |
---|
501 | if (dbufCount) { |
---|
502 | if (origPtr >= dbufCount) return RETVAL_DATA_ERROR; |
---|
503 | bd->writePos = dbuf[origPtr]; |
---|
504 | bd->writeCurrent = (unsigned char)(bd->writePos & 0xff); |
---|
505 | bd->writePos >>= 8; |
---|
506 | bd->writeRunCountdown = 5; |
---|
507 | } |
---|
508 | bd->writeCount = dbufCount; |
---|
509 | |
---|
510 | return RETVAL_OK; |
---|
511 | } |
---|
512 | |
---|
513 | /* Undo burrows-wheeler transform on intermediate buffer to produce output. |
---|
514 | If start_bunzip was initialized with out_fd=-1, then up to len bytes of |
---|
515 | data are written to outbuf. Return value is number of bytes written or |
---|
516 | error (all errors are negative numbers). If out_fd!=-1, outbuf and len |
---|
517 | are ignored, data is written to out_fd and return is RETVAL_OK or error. |
---|
518 | */ |
---|
519 | |
---|
520 | int read_bunzip(bunzip_data *bd, char *outbuf, int len) |
---|
521 | { |
---|
522 | const unsigned *dbuf; |
---|
523 | int pos, current, previous, gotcount; |
---|
524 | |
---|
525 | /* If last read was short due to end of file, return last block now */ |
---|
526 | if (bd->writeCount < 0) return bd->writeCount; |
---|
527 | |
---|
528 | gotcount = 0; |
---|
529 | dbuf = bd->dbuf; |
---|
530 | pos = bd->writePos; |
---|
531 | current = bd->writeCurrent; |
---|
532 | |
---|
533 | /* We will always have pending decoded data to write into the output |
---|
534 | buffer unless this is the very first call (in which case we haven't |
---|
535 | Huffman-decoded a block into the intermediate buffer yet). */ |
---|
536 | |
---|
537 | if (bd->writeCopies) { |
---|
538 | |
---|
539 | /* Inside the loop, writeCopies means extra copies (beyond 1) */ |
---|
540 | |
---|
541 | --bd->writeCopies; |
---|
542 | |
---|
543 | /* Loop outputting bytes */ |
---|
544 | |
---|
545 | for (;;) { |
---|
546 | |
---|
547 | /* If the output buffer is full, snapshot state and return */ |
---|
548 | |
---|
549 | if (gotcount >= len) { |
---|
550 | bd->writePos =pos; |
---|
551 | bd->writeCurrent = current; |
---|
552 | bd->writeCopies++; |
---|
553 | return len; |
---|
554 | } |
---|
555 | |
---|
556 | /* Write next byte into output buffer, updating CRC */ |
---|
557 | |
---|
558 | outbuf[gotcount++] = current; |
---|
559 | bd->writeCRC = (bd->writeCRC << 8) |
---|
560 | ^ bd->crc32Table[(bd->writeCRC >> 24) ^ current]; |
---|
561 | |
---|
562 | /* Loop now if we're outputting multiple copies of this byte */ |
---|
563 | |
---|
564 | if (bd->writeCopies) { |
---|
565 | --bd->writeCopies; |
---|
566 | continue; |
---|
567 | } |
---|
568 | decode_next_byte: |
---|
569 | if (!bd->writeCount--) break; |
---|
570 | /* Follow sequence vector to undo Burrows-Wheeler transform */ |
---|
571 | previous = current; |
---|
572 | pos = dbuf[pos]; |
---|
573 | current = pos & 0xff; |
---|
574 | pos >>= 8; |
---|
575 | |
---|
576 | /* After 3 consecutive copies of the same byte, the 4th is a repeat |
---|
577 | count. We count down from 4 instead |
---|
578 | * of counting up because testing for non-zero is faster */ |
---|
579 | |
---|
580 | if (--bd->writeRunCountdown) { |
---|
581 | if (current != previous) |
---|
582 | bd->writeRunCountdown = 4; |
---|
583 | } else { |
---|
584 | |
---|
585 | /* We have a repeated run, this byte indicates the count */ |
---|
586 | |
---|
587 | bd->writeCopies = current; |
---|
588 | current = previous; |
---|
589 | bd->writeRunCountdown = 5; |
---|
590 | |
---|
591 | /* Sometimes there are just 3 bytes (run length 0) */ |
---|
592 | |
---|
593 | if (!bd->writeCopies) goto decode_next_byte; |
---|
594 | |
---|
595 | /* Subtract the 1 copy we'd output anyway to get extras */ |
---|
596 | |
---|
597 | --bd->writeCopies; |
---|
598 | } |
---|
599 | } |
---|
600 | |
---|
601 | /* Decompression of this block completed successfully */ |
---|
602 | |
---|
603 | bd->writeCRC = ~bd->writeCRC; |
---|
604 | bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ bd->writeCRC; |
---|
605 | |
---|
606 | /* If this block had a CRC error, force file level CRC error. */ |
---|
607 | |
---|
608 | if (bd->writeCRC != bd->headerCRC) { |
---|
609 | bd->totalCRC = bd->headerCRC+1; |
---|
610 | return RETVAL_LAST_BLOCK; |
---|
611 | } |
---|
612 | } |
---|
613 | |
---|
614 | /* Refill the intermediate buffer by Huffman-decoding next block of input */ |
---|
615 | /* (previous is just a convenient unused temp variable here) */ |
---|
616 | |
---|
617 | previous = get_next_block(bd); |
---|
618 | if (previous) { |
---|
619 | bd->writeCount = previous; |
---|
620 | return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount; |
---|
621 | } |
---|
622 | bd->writeCRC = ~0; |
---|
623 | pos = bd->writePos; |
---|
624 | current = bd->writeCurrent; |
---|
625 | goto decode_next_byte; |
---|
626 | } |
---|
627 | |
---|
628 | |
---|
629 | /* Allocate the structure, read file header. If in_fd==-1, inbuf must contain |
---|
630 | a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are |
---|
631 | ignored, and data is read from file handle into temporary buffer. */ |
---|
632 | |
---|
633 | /* Because bunzip2 is used for help text unpacking, and because bb_show_usage() |
---|
634 | should work for NOFORK applets too, we must be extremely careful to not leak |
---|
635 | any allocations! */ |
---|
636 | |
---|
637 | int start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *inbuf, |
---|
638 | int len) |
---|
639 | { |
---|
640 | bunzip_data *bd; |
---|
641 | unsigned i; |
---|
642 | enum { |
---|
643 | BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0' |
---|
644 | }; |
---|
645 | |
---|
646 | /* Figure out how much data to allocate */ |
---|
647 | |
---|
648 | i = sizeof(bunzip_data); |
---|
649 | if (in_fd != -1) i += IOBUF_SIZE; |
---|
650 | |
---|
651 | /* Allocate bunzip_data. Most fields initialize to zero. */ |
---|
652 | |
---|
653 | bd = *bdp = xzalloc(i); |
---|
654 | |
---|
655 | /* Setup input buffer */ |
---|
656 | |
---|
657 | bd->in_fd = in_fd; |
---|
658 | if (-1 == in_fd) { |
---|
659 | /* in this case, bd->inbuf is read-only */ |
---|
660 | bd->inbuf = (void*)inbuf; /* cast away const-ness */ |
---|
661 | bd->inbufCount = len; |
---|
662 | } else |
---|
663 | bd->inbuf = (unsigned char *)(bd + 1); |
---|
664 | |
---|
665 | /* Init the CRC32 table (big endian) */ |
---|
666 | |
---|
667 | crc32_filltable(bd->crc32Table, 1); |
---|
668 | |
---|
669 | /* Setup for I/O error handling via longjmp */ |
---|
670 | |
---|
671 | i = setjmp(bd->jmpbuf); |
---|
672 | if (i) return i; |
---|
673 | |
---|
674 | /* Ensure that file starts with "BZh['1'-'9']." */ |
---|
675 | |
---|
676 | i = get_bits(bd, 32); |
---|
677 | if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; |
---|
678 | |
---|
679 | /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of |
---|
680 | uncompressed data. Allocate intermediate buffer for block. */ |
---|
681 | |
---|
682 | bd->dbufSize = 100000 * (i - BZh0); |
---|
683 | |
---|
684 | /* Cannot use xmalloc - may leak bd in NOFORK case! */ |
---|
685 | bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(int)); |
---|
686 | if (!bd->dbuf) { |
---|
687 | free(bd); |
---|
688 | xfunc_die(); |
---|
689 | } |
---|
690 | return RETVAL_OK; |
---|
691 | } |
---|
692 | |
---|
693 | void dealloc_bunzip(bunzip_data *bd) |
---|
694 | { |
---|
695 | free(bd->dbuf); |
---|
696 | free(bd); |
---|
697 | } |
---|
698 | |
---|
699 | |
---|
700 | /* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */ |
---|
701 | |
---|
702 | USE_DESKTOP(long long) int |
---|
703 | unpack_bz2_stream(int src_fd, int dst_fd) |
---|
704 | { |
---|
705 | USE_DESKTOP(long long total_written = 0;) |
---|
706 | char *outbuf; |
---|
707 | bunzip_data *bd; |
---|
708 | int i; |
---|
709 | |
---|
710 | outbuf = xmalloc(IOBUF_SIZE); |
---|
711 | i = start_bunzip(&bd, src_fd, NULL, 0); |
---|
712 | if (!i) { |
---|
713 | for (;;) { |
---|
714 | i = read_bunzip(bd, outbuf, IOBUF_SIZE); |
---|
715 | if (i <= 0) break; |
---|
716 | if (i != safe_write(dst_fd, outbuf, i)) { |
---|
717 | i = RETVAL_UNEXPECTED_OUTPUT_EOF; |
---|
718 | break; |
---|
719 | } |
---|
720 | USE_DESKTOP(total_written += i;) |
---|
721 | } |
---|
722 | } |
---|
723 | |
---|
724 | /* Check CRC and release memory */ |
---|
725 | |
---|
726 | if (i == RETVAL_LAST_BLOCK) { |
---|
727 | if (bd->headerCRC != bd->totalCRC) { |
---|
728 | bb_error_msg("data integrity error when decompressing"); |
---|
729 | } else { |
---|
730 | i = RETVAL_OK; |
---|
731 | } |
---|
732 | } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) { |
---|
733 | bb_error_msg("compressed file ends unexpectedly"); |
---|
734 | } else { |
---|
735 | bb_error_msg("decompression failed"); |
---|
736 | } |
---|
737 | dealloc_bunzip(bd); |
---|
738 | free(outbuf); |
---|
739 | |
---|
740 | return i ? i : USE_DESKTOP(total_written) + 0; |
---|
741 | } |
---|
742 | |
---|
743 | #ifdef TESTING |
---|
744 | |
---|
745 | static char *const bunzip_errors[] = { |
---|
746 | NULL, "Bad file checksum", "Not bzip data", |
---|
747 | "Unexpected input EOF", "Unexpected output EOF", "Data error", |
---|
748 | "Out of memory", "Obsolete (pre 0.9.5) bzip format not supported" |
---|
749 | }; |
---|
750 | |
---|
751 | /* Dumb little test thing, decompress stdin to stdout */ |
---|
752 | int main(int argc, char **argv) |
---|
753 | { |
---|
754 | int i = unpack_bz2_stream(0, 1); |
---|
755 | char c; |
---|
756 | |
---|
757 | if (i < 0) |
---|
758 | fprintf(stderr,"%s\n", bunzip_errors[-i]); |
---|
759 | else if (read(0, &c, 1)) |
---|
760 | fprintf(stderr,"Trailing garbage ignored\n"); |
---|
761 | return -i; |
---|
762 | } |
---|
763 | #endif |
---|