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 <setjmp.h>
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32 | #include <stdio.h>
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33 | #include <stdlib.h>
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34 | #include <string.h>
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35 | #include <unistd.h>
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36 | #include <limits.h>
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37 |
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38 | #include "libbb.h"
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39 |
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40 | #include "unarchive.h"
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41 |
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42 | /* Constants for Huffman coding */
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43 | #define MAX_GROUPS 6
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44 | #define GROUP_SIZE 50 /* 64 would have been more efficient */
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45 | #define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */
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46 | #define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */
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47 | #define SYMBOL_RUNA 0
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48 | #define SYMBOL_RUNB 1
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49 |
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50 | /* Status return values */
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51 | #define RETVAL_OK 0
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52 | #define RETVAL_LAST_BLOCK (-1)
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53 | #define RETVAL_NOT_BZIP_DATA (-2)
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54 | #define RETVAL_UNEXPECTED_INPUT_EOF (-3)
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55 | #define RETVAL_UNEXPECTED_OUTPUT_EOF (-4)
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56 | #define RETVAL_DATA_ERROR (-5)
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57 | #define RETVAL_OUT_OF_MEMORY (-6)
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58 | #define RETVAL_OBSOLETE_INPUT (-7)
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59 |
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60 | /* Other housekeeping constants */
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61 | #define IOBUF_SIZE 4096
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62 |
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63 | /* This is what we know about each Huffman coding group */
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64 | struct group_data {
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65 | /* We have an extra slot at the end of limit[] for a sentinal value. */
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66 | int limit[MAX_HUFCODE_BITS+1],base[MAX_HUFCODE_BITS],permute[MAX_SYMBOLS];
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67 | int minLen, maxLen;
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68 | };
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69 |
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70 | /* Structure holding all the housekeeping data, including IO buffers and
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71 | memory that persists between calls to bunzip */
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72 |
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73 | typedef struct {
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74 | /* State for interrupting output loop */
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75 |
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76 | int writeCopies,writePos,writeRunCountdown,writeCount,writeCurrent;
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77 |
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78 | /* I/O tracking data (file handles, buffers, positions, etc.) */
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79 |
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80 | int in_fd,out_fd,inbufCount,inbufPos /*,outbufPos*/;
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81 | unsigned char *inbuf /*,*outbuf*/;
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82 | unsigned int inbufBitCount, inbufBits;
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83 |
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84 | /* The CRC values stored in the block header and calculated from the data */
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85 |
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86 | uint32_t headerCRC, totalCRC, writeCRC;
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87 | uint32_t *crc32Table;
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88 | /* Intermediate buffer and its size (in bytes) */
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89 |
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90 | unsigned int *dbuf, dbufSize;
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91 |
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92 | /* These things are a bit too big to go on the stack */
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93 |
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94 | unsigned char selectors[32768]; /* nSelectors=15 bits */
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95 | struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */
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96 |
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97 | /* For I/O error handling */
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98 |
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99 | jmp_buf jmpbuf;
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100 | } bunzip_data;
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101 |
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102 | /* Return the next nnn bits of input. All reads from the compressed input
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103 | are done through this function. All reads are big endian */
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104 |
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105 | static unsigned int get_bits(bunzip_data *bd, char bits_wanted)
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106 | {
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107 | unsigned int bits=0;
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108 |
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109 | /* If we need to get more data from the byte buffer, do so. (Loop getting
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110 | one byte at a time to enforce endianness and avoid unaligned access.) */
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111 |
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112 | while (bd->inbufBitCount<bits_wanted) {
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113 |
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114 | /* If we need to read more data from file into byte buffer, do so */
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115 |
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116 | if(bd->inbufPos==bd->inbufCount) {
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117 | if((bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE)) <= 0)
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118 | longjmp(bd->jmpbuf,RETVAL_UNEXPECTED_INPUT_EOF);
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119 | bd->inbufPos=0;
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120 | }
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121 |
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122 | /* Avoid 32-bit overflow (dump bit buffer to top of output) */
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123 |
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124 | if(bd->inbufBitCount>=24) {
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125 | bits=bd->inbufBits&((1<<bd->inbufBitCount)-1);
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126 | bits_wanted-=bd->inbufBitCount;
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127 | bits<<=bits_wanted;
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128 | bd->inbufBitCount=0;
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129 | }
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130 |
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131 | /* Grab next 8 bits of input from buffer. */
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132 |
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133 | bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++];
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134 | bd->inbufBitCount+=8;
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135 | }
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136 |
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137 | /* Calculate result */
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138 |
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139 | bd->inbufBitCount-=bits_wanted;
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140 | bits|=(bd->inbufBits>>bd->inbufBitCount)&((1<<bits_wanted)-1);
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141 |
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142 | return bits;
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143 | }
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144 |
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145 | /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
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146 |
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147 | static int get_next_block(bunzip_data *bd)
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148 | {
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149 | struct group_data *hufGroup;
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150 | int dbufCount,nextSym,dbufSize,groupCount,*base,*limit,selector,
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151 | i,j,k,t,runPos,symCount,symTotal,nSelectors,byteCount[256];
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152 | unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
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153 | unsigned int *dbuf,origPtr;
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154 |
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155 | dbuf=bd->dbuf;
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156 | dbufSize=bd->dbufSize;
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157 | selectors=bd->selectors;
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158 |
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159 | /* Reset longjmp I/O error handling */
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160 |
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161 | i=setjmp(bd->jmpbuf);
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162 | if(i) return i;
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163 |
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164 | /* Read in header signature and CRC, then validate signature.
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165 | (last block signature means CRC is for whole file, return now) */
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166 |
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167 | i = get_bits(bd,24);
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168 | j = get_bits(bd,24);
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169 | bd->headerCRC=get_bits(bd,32);
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170 | if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK;
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171 | if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA;
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172 |
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173 | /* We can add support for blockRandomised if anybody complains. There was
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174 | some code for this in busybox 1.0.0-pre3, but nobody ever noticed that
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175 | it didn't actually work. */
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176 |
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177 | if(get_bits(bd,1)) return RETVAL_OBSOLETE_INPUT;
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178 | if((origPtr=get_bits(bd,24)) > dbufSize) return RETVAL_DATA_ERROR;
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179 |
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180 | /* mapping table: if some byte values are never used (encoding things
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181 | like ascii text), the compression code removes the gaps to have fewer
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182 | symbols to deal with, and writes a sparse bitfield indicating which
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183 | values were present. We make a translation table to convert the symbols
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184 | back to the corresponding bytes. */
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185 |
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186 | t=get_bits(bd, 16);
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187 | symTotal=0;
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188 | for (i=0;i<16;i++) {
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189 | if(t&(1<<(15-i))) {
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190 | k=get_bits(bd,16);
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191 | for(j=0;j<16;j++)
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192 | if(k&(1<<(15-j))) symToByte[symTotal++]=(16*i)+j;
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193 | }
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194 | }
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195 |
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196 | /* How many different Huffman coding groups does this block use? */
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197 |
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198 | groupCount=get_bits(bd,3);
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199 | if (groupCount<2 || groupCount>MAX_GROUPS) return RETVAL_DATA_ERROR;
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200 |
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201 | /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding
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202 | group. Read in the group selector list, which is stored as MTF encoded
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203 | bit runs. (MTF=Move To Front, as each value is used it's moved to the
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204 | start of the list.) */
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205 |
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206 | if(!(nSelectors=get_bits(bd, 15))) return RETVAL_DATA_ERROR;
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207 | for(i=0; i<groupCount; i++) mtfSymbol[i] = i;
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208 | for(i=0; i<nSelectors; i++) {
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209 |
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210 | /* Get next value */
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211 |
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212 | for(j=0;get_bits(bd,1);j++) if (j>=groupCount) return RETVAL_DATA_ERROR;
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213 |
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214 | /* Decode MTF to get the next selector */
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215 |
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216 | uc = mtfSymbol[j];
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217 | for(;j;j--) mtfSymbol[j] = mtfSymbol[j-1];
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218 | mtfSymbol[0]=selectors[i]=uc;
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219 | }
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220 |
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221 | /* Read the Huffman coding tables for each group, which code for symTotal
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222 | literal symbols, plus two run symbols (RUNA, RUNB) */
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223 |
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224 | symCount=symTotal+2;
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225 | for (j=0; j<groupCount; j++) {
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226 | unsigned char length[MAX_SYMBOLS],temp[MAX_HUFCODE_BITS+1];
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227 | int minLen, maxLen, pp;
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228 |
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229 | /* Read Huffman code lengths for each symbol. They're stored in
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230 | a way similar to mtf; record a starting value for the first symbol,
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231 | and an offset from the previous value for everys symbol after that.
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232 | (Subtracting 1 before the loop and then adding it back at the end is
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233 | an optimization that makes the test inside the loop simpler: symbol
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234 | length 0 becomes negative, so an unsigned inequality catches it.) */
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235 |
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236 | t=get_bits(bd, 5)-1;
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237 | for (i = 0; i < symCount; i++) {
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238 | for(;;) {
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239 | if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
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240 | return RETVAL_DATA_ERROR;
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241 |
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242 | /* If first bit is 0, stop. Else second bit indicates whether
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243 | to increment or decrement the value. Optimization: grab 2
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244 | bits and unget the second if the first was 0. */
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245 |
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246 | k = get_bits(bd,2);
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247 | if (k < 2) {
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248 | bd->inbufBitCount++;
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249 | break;
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250 | }
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251 |
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252 | /* Add one if second bit 1, else subtract 1. Avoids if/else */
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253 |
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254 | t+=(((k+1)&2)-1);
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255 | }
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256 |
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257 | /* Correct for the initial -1, to get the final symbol length */
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258 |
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259 | length[i]=t+1;
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260 | }
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261 |
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262 | /* Find largest and smallest lengths in this group */
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263 |
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264 | minLen=maxLen=length[0];
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265 | for(i = 1; i < symCount; i++) {
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266 | if(length[i] > maxLen) maxLen = length[i];
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267 | else if(length[i] < minLen) minLen = length[i];
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268 | }
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269 |
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270 | /* Calculate permute[], base[], and limit[] tables from length[].
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271 | *
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272 | * permute[] is the lookup table for converting Huffman coded symbols
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273 | * into decoded symbols. base[] is the amount to subtract from the
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274 | * value of a Huffman symbol of a given length when using permute[].
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275 | *
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276 | * limit[] indicates the largest numerical value a symbol with a given
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277 | * number of bits can have. This is how the Huffman codes can vary in
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278 | * length: each code with a value>limit[length] needs another bit.
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279 | */
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280 |
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281 | hufGroup=bd->groups+j;
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282 | hufGroup->minLen = minLen;
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283 | hufGroup->maxLen = maxLen;
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284 |
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285 | /* Note that minLen can't be smaller than 1, so we adjust the base
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286 | and limit array pointers so we're not always wasting the first
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287 | entry. We do this again when using them (during symbol decoding).*/
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288 |
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289 | base=hufGroup->base-1;
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290 | limit=hufGroup->limit-1;
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291 |
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292 | /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */
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293 |
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294 | pp=0;
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295 | for(i=minLen;i<=maxLen;i++) {
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296 | temp[i]=limit[i]=0;
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297 | for(t=0;t<symCount;t++)
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298 | if(length[t]==i) hufGroup->permute[pp++] = t;
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299 | }
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300 |
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301 | /* Count symbols coded for at each bit length */
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302 |
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303 | for (i=0;i<symCount;i++) temp[length[i]]++;
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304 |
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305 | /* Calculate limit[] (the largest symbol-coding value at each bit
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306 | * length, which is (previous limit<<1)+symbols at this level), and
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307 | * base[] (number of symbols to ignore at each bit length, which is
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308 | * limit minus the cumulative count of symbols coded for already). */
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309 |
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310 | pp=t=0;
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311 | for (i=minLen; i<maxLen; i++) {
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312 | pp+=temp[i];
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313 |
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314 | /* We read the largest possible symbol size and then unget bits
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315 | after determining how many we need, and those extra bits could
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316 | be set to anything. (They're noise from future symbols.) At
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317 | each level we're really only interested in the first few bits,
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318 | so here we set all the trailing to-be-ignored bits to 1 so they
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319 | don't affect the value>limit[length] comparison. */
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320 |
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321 | limit[i]= (pp << (maxLen - i)) - 1;
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322 | pp<<=1;
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323 | base[i+1]=pp-(t+=temp[i]);
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324 | }
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325 | limit[maxLen+1] = INT_MAX; /* Sentinal value for reading next sym. */
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326 | limit[maxLen]=pp+temp[maxLen]-1;
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327 | base[minLen]=0;
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328 | }
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329 |
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330 | /* We've finished reading and digesting the block header. Now read this
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331 | block's Huffman coded symbols from the file and undo the Huffman coding
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332 | and run length encoding, saving the result into dbuf[dbufCount++]=uc */
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333 |
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334 | /* Initialize symbol occurrence counters and symbol Move To Front table */
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335 |
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336 | for(i=0;i<256;i++) {
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337 | byteCount[i] = 0;
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338 | mtfSymbol[i]=(unsigned char)i;
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339 | }
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340 |
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341 | /* Loop through compressed symbols. */
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342 |
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343 | runPos=dbufCount=selector=0;
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344 | for(;;) {
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345 |
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346 | /* fetch next Huffman coding group from list. */
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347 |
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348 | symCount=GROUP_SIZE-1;
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349 | if(selector>=nSelectors) return RETVAL_DATA_ERROR;
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350 | hufGroup=bd->groups+selectors[selector++];
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351 | base=hufGroup->base-1;
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352 | limit=hufGroup->limit-1;
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353 | continue_this_group:
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354 |
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355 | /* Read next Huffman-coded symbol. */
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356 |
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357 | /* Note: It is far cheaper to read maxLen bits and back up than it is
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358 | to read minLen bits and then an additional bit at a time, testing
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359 | as we go. Because there is a trailing last block (with file CRC),
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360 | there is no danger of the overread causing an unexpected EOF for a
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361 | valid compressed file. As a further optimization, we do the read
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362 | inline (falling back to a call to get_bits if the buffer runs
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363 | dry). The following (up to got_huff_bits:) is equivalent to
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364 | j=get_bits(bd,hufGroup->maxLen);
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365 | */
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366 |
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367 | while (bd->inbufBitCount<hufGroup->maxLen) {
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368 | if(bd->inbufPos==bd->inbufCount) {
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369 | j = get_bits(bd,hufGroup->maxLen);
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370 | goto got_huff_bits;
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371 | }
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372 | bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++];
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373 | bd->inbufBitCount+=8;
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374 | };
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375 | bd->inbufBitCount-=hufGroup->maxLen;
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376 | j = (bd->inbufBits>>bd->inbufBitCount)&((1<<hufGroup->maxLen)-1);
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377 |
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378 | got_huff_bits:
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379 |
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380 | /* Figure how how many bits are in next symbol and unget extras */
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381 |
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382 | i=hufGroup->minLen;
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383 | while(j>limit[i]) ++i;
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384 | bd->inbufBitCount += (hufGroup->maxLen - i);
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385 |
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386 | /* Huffman decode value to get nextSym (with bounds checking) */
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387 |
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388 | if ((i > hufGroup->maxLen)
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389 | || (((unsigned)(j=(j>>(hufGroup->maxLen-i))-base[i]))
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390 | >= MAX_SYMBOLS))
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391 | return RETVAL_DATA_ERROR;
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392 | nextSym = hufGroup->permute[j];
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393 |
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394 | /* We have now decoded the symbol, which indicates either a new literal
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395 | byte, or a repeated run of the most recent literal byte. First,
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396 | check if nextSym indicates a repeated run, and if so loop collecting
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397 | how many times to repeat the last literal. */
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398 |
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399 | if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
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400 |
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401 | /* If this is the start of a new run, zero out counter */
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402 |
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403 | if(!runPos) {
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404 | runPos = 1;
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405 | t = 0;
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406 | }
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407 |
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408 | /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at
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409 | each bit position, add 1 or 2 instead. For example,
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410 | 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2.
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411 | You can make any bit pattern that way using 1 less symbol than
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412 | the basic or 0/1 method (except all bits 0, which would use no
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413 | symbols, but a run of length 0 doesn't mean anything in this
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414 | context). Thus space is saved. */
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415 |
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416 | t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */
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417 | if(runPos < dbufSize) runPos <<= 1;
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418 | goto end_of_huffman_loop;
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419 | }
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420 |
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421 | /* When we hit the first non-run symbol after a run, we now know
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422 | how many times to repeat the last literal, so append that many
|
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423 | copies to our buffer of decoded symbols (dbuf) now. (The last
|
---|
424 | literal used is the one at the head of the mtfSymbol array.) */
|
---|
425 |
|
---|
426 | if(runPos) {
|
---|
427 | runPos=0;
|
---|
428 | if(dbufCount+t>=dbufSize) return RETVAL_DATA_ERROR;
|
---|
429 |
|
---|
430 | uc = symToByte[mtfSymbol[0]];
|
---|
431 | byteCount[uc] += t;
|
---|
432 | while(t--) dbuf[dbufCount++]=uc;
|
---|
433 | }
|
---|
434 |
|
---|
435 | /* Is this the terminating symbol? */
|
---|
436 |
|
---|
437 | if(nextSym>symTotal) break;
|
---|
438 |
|
---|
439 | /* At this point, nextSym indicates a new literal character. Subtract
|
---|
440 | one to get the position in the MTF array at which this literal is
|
---|
441 | currently to be found. (Note that the result can't be -1 or 0,
|
---|
442 | because 0 and 1 are RUNA and RUNB. But another instance of the
|
---|
443 | first symbol in the mtf array, position 0, would have been handled
|
---|
444 | as part of a run above. Therefore 1 unused mtf position minus
|
---|
445 | 2 non-literal nextSym values equals -1.) */
|
---|
446 |
|
---|
447 | if(dbufCount>=dbufSize) return RETVAL_DATA_ERROR;
|
---|
448 | i = nextSym - 1;
|
---|
449 | uc = mtfSymbol[i];
|
---|
450 |
|
---|
451 | /* Adjust the MTF array. Since we typically expect to move only a
|
---|
452 | * small number of symbols, and are bound by 256 in any case, using
|
---|
453 | * memmove here would typically be bigger and slower due to function
|
---|
454 | * call overhead and other assorted setup costs. */
|
---|
455 |
|
---|
456 | do {
|
---|
457 | mtfSymbol[i] = mtfSymbol[i-1];
|
---|
458 | } while (--i);
|
---|
459 | mtfSymbol[0] = uc;
|
---|
460 | uc=symToByte[uc];
|
---|
461 |
|
---|
462 | /* We have our literal byte. Save it into dbuf. */
|
---|
463 |
|
---|
464 | byteCount[uc]++;
|
---|
465 | dbuf[dbufCount++] = (unsigned int)uc;
|
---|
466 |
|
---|
467 | /* Skip group initialization if we're not done with this group. Done
|
---|
468 | * this way to avoid compiler warning. */
|
---|
469 |
|
---|
470 | end_of_huffman_loop:
|
---|
471 | if(symCount--) goto continue_this_group;
|
---|
472 | }
|
---|
473 |
|
---|
474 | /* At this point, we've read all the Huffman-coded symbols (and repeated
|
---|
475 | runs) for this block from the input stream, and decoded them into the
|
---|
476 | intermediate buffer. There are dbufCount many decoded bytes in dbuf[].
|
---|
477 | Now undo the Burrows-Wheeler transform on dbuf.
|
---|
478 | See http://dogma.net/markn/articles/bwt/bwt.htm
|
---|
479 | */
|
---|
480 |
|
---|
481 | /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
|
---|
482 |
|
---|
483 | j=0;
|
---|
484 | for(i=0;i<256;i++) {
|
---|
485 | k=j+byteCount[i];
|
---|
486 | byteCount[i] = j;
|
---|
487 | j=k;
|
---|
488 | }
|
---|
489 |
|
---|
490 | /* Figure out what order dbuf would be in if we sorted it. */
|
---|
491 |
|
---|
492 | for (i=0;i<dbufCount;i++) {
|
---|
493 | uc=(unsigned char)(dbuf[i] & 0xff);
|
---|
494 | dbuf[byteCount[uc]] |= (i << 8);
|
---|
495 | byteCount[uc]++;
|
---|
496 | }
|
---|
497 |
|
---|
498 | /* Decode first byte by hand to initialize "previous" byte. Note that it
|
---|
499 | doesn't get output, and if the first three characters are identical
|
---|
500 | it doesn't qualify as a run (hence writeRunCountdown=5). */
|
---|
501 |
|
---|
502 | if(dbufCount) {
|
---|
503 | if(origPtr>=dbufCount) return RETVAL_DATA_ERROR;
|
---|
504 | bd->writePos=dbuf[origPtr];
|
---|
505 | bd->writeCurrent=(unsigned char)(bd->writePos&0xff);
|
---|
506 | bd->writePos>>=8;
|
---|
507 | bd->writeRunCountdown=5;
|
---|
508 | }
|
---|
509 | bd->writeCount=dbufCount;
|
---|
510 |
|
---|
511 | return RETVAL_OK;
|
---|
512 | }
|
---|
513 |
|
---|
514 | /* Undo burrows-wheeler transform on intermediate buffer to produce output.
|
---|
515 | If start_bunzip was initialized with out_fd=-1, then up to len bytes of
|
---|
516 | data are written to outbuf. Return value is number of bytes written or
|
---|
517 | error (all errors are negative numbers). If out_fd!=-1, outbuf and len
|
---|
518 | are ignored, data is written to out_fd and return is RETVAL_OK or error.
|
---|
519 | */
|
---|
520 |
|
---|
521 | static int read_bunzip(bunzip_data *bd, char *outbuf, int len)
|
---|
522 | {
|
---|
523 | const unsigned int *dbuf;
|
---|
524 | int pos,current,previous,gotcount;
|
---|
525 |
|
---|
526 | /* If last read was short due to end of file, return last block now */
|
---|
527 | if(bd->writeCount<0) return bd->writeCount;
|
---|
528 |
|
---|
529 | gotcount = 0;
|
---|
530 | dbuf=bd->dbuf;
|
---|
531 | pos=bd->writePos;
|
---|
532 | current=bd->writeCurrent;
|
---|
533 |
|
---|
534 | /* We will always have pending decoded data to write into the output
|
---|
535 | buffer unless this is the very first call (in which case we haven't
|
---|
536 | Huffman-decoded a block into the intermediate buffer yet). */
|
---|
537 |
|
---|
538 | if (bd->writeCopies) {
|
---|
539 |
|
---|
540 | /* Inside the loop, writeCopies means extra copies (beyond 1) */
|
---|
541 |
|
---|
542 | --bd->writeCopies;
|
---|
543 |
|
---|
544 | /* Loop outputting bytes */
|
---|
545 |
|
---|
546 | for(;;) {
|
---|
547 |
|
---|
548 | /* If the output buffer is full, snapshot state and return */
|
---|
549 |
|
---|
550 | if(gotcount >= len) {
|
---|
551 | bd->writePos=pos;
|
---|
552 | bd->writeCurrent=current;
|
---|
553 | bd->writeCopies++;
|
---|
554 | return len;
|
---|
555 | }
|
---|
556 |
|
---|
557 | /* Write next byte into output buffer, updating CRC */
|
---|
558 |
|
---|
559 | outbuf[gotcount++] = current;
|
---|
560 | bd->writeCRC=(((bd->writeCRC)<<8)
|
---|
561 | ^bd->crc32Table[((bd->writeCRC)>>24)^current]);
|
---|
562 |
|
---|
563 | /* Loop now if we're outputting multiple copies of this byte */
|
---|
564 |
|
---|
565 | if (bd->writeCopies) {
|
---|
566 | --bd->writeCopies;
|
---|
567 | continue;
|
---|
568 | }
|
---|
569 | decode_next_byte:
|
---|
570 | if (!bd->writeCount--) break;
|
---|
571 | /* Follow sequence vector to undo Burrows-Wheeler transform */
|
---|
572 | previous=current;
|
---|
573 | pos=dbuf[pos];
|
---|
574 | current=pos&0xff;
|
---|
575 | pos>>=8;
|
---|
576 |
|
---|
577 | /* After 3 consecutive copies of the same byte, the 4th is a repeat
|
---|
578 | count. We count down from 4 instead
|
---|
579 | * of counting up because testing for non-zero is faster */
|
---|
580 |
|
---|
581 | if(--bd->writeRunCountdown) {
|
---|
582 | if(current!=previous) 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 | /* Allocate the structure, read file header. If in_fd==-1, inbuf must contain
|
---|
629 | a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
|
---|
630 | ignored, and data is read from file handle into temporary buffer. */
|
---|
631 |
|
---|
632 | static int start_bunzip(bunzip_data **bdp, int in_fd, unsigned char *inbuf,
|
---|
633 | int len)
|
---|
634 | {
|
---|
635 | bunzip_data *bd;
|
---|
636 | unsigned int i;
|
---|
637 | const unsigned int BZh0=(((unsigned int)'B')<<24)+(((unsigned int)'Z')<<16)
|
---|
638 | +(((unsigned int)'h')<<8)+(unsigned int)'0';
|
---|
639 |
|
---|
640 | /* Figure out how much data to allocate */
|
---|
641 |
|
---|
642 | i=sizeof(bunzip_data);
|
---|
643 | if(in_fd!=-1) i+=IOBUF_SIZE;
|
---|
644 |
|
---|
645 | /* Allocate bunzip_data. Most fields initialize to zero. */
|
---|
646 |
|
---|
647 | bd=*bdp=xzalloc(i);
|
---|
648 |
|
---|
649 | /* Setup input buffer */
|
---|
650 |
|
---|
651 | if(-1==(bd->in_fd=in_fd)) {
|
---|
652 | bd->inbuf=inbuf;
|
---|
653 | bd->inbufCount=len;
|
---|
654 | } else bd->inbuf=(unsigned char *)(bd+1);
|
---|
655 |
|
---|
656 | /* Init the CRC32 table (big endian) */
|
---|
657 |
|
---|
658 | bd->crc32Table = bb_crc32_filltable(1);
|
---|
659 |
|
---|
660 | /* Setup for I/O error handling via longjmp */
|
---|
661 |
|
---|
662 | i=setjmp(bd->jmpbuf);
|
---|
663 | if(i) return i;
|
---|
664 |
|
---|
665 | /* Ensure that file starts with "BZh['1'-'9']." */
|
---|
666 |
|
---|
667 | i = get_bits(bd,32);
|
---|
668 | if (((unsigned int)(i-BZh0-1)) >= 9) return RETVAL_NOT_BZIP_DATA;
|
---|
669 |
|
---|
670 | /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
|
---|
671 | uncompressed data. Allocate intermediate buffer for block. */
|
---|
672 |
|
---|
673 | bd->dbufSize=100000*(i-BZh0);
|
---|
674 |
|
---|
675 | bd->dbuf=xmalloc(bd->dbufSize * sizeof(int));
|
---|
676 | return RETVAL_OK;
|
---|
677 | }
|
---|
678 |
|
---|
679 | /* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip data,
|
---|
680 | not end of file.) */
|
---|
681 |
|
---|
682 | int uncompressStream(int src_fd, int dst_fd)
|
---|
683 | {
|
---|
684 | char *outbuf;
|
---|
685 | bunzip_data *bd;
|
---|
686 | int i;
|
---|
687 |
|
---|
688 | outbuf=xmalloc(IOBUF_SIZE);
|
---|
689 | if(!(i=start_bunzip(&bd,src_fd,0,0))) {
|
---|
690 | for(;;) {
|
---|
691 | if((i=read_bunzip(bd,outbuf,IOBUF_SIZE)) <= 0) break;
|
---|
692 | if(i!=write(dst_fd,outbuf,i)) {
|
---|
693 | i=RETVAL_UNEXPECTED_OUTPUT_EOF;
|
---|
694 | break;
|
---|
695 | }
|
---|
696 | }
|
---|
697 | }
|
---|
698 |
|
---|
699 | /* Check CRC and release memory */
|
---|
700 |
|
---|
701 | if(i==RETVAL_LAST_BLOCK) {
|
---|
702 | if (bd->headerCRC!=bd->totalCRC) {
|
---|
703 | bb_error_msg("Data integrity error when decompressing.");
|
---|
704 | } else {
|
---|
705 | i=RETVAL_OK;
|
---|
706 | }
|
---|
707 | } else if (i==RETVAL_UNEXPECTED_OUTPUT_EOF) {
|
---|
708 | bb_error_msg("Compressed file ends unexpectedly");
|
---|
709 | } else {
|
---|
710 | bb_error_msg("Decompression failed");
|
---|
711 | }
|
---|
712 | free(bd->dbuf);
|
---|
713 | free(bd);
|
---|
714 | free(outbuf);
|
---|
715 |
|
---|
716 | return i;
|
---|
717 | }
|
---|
718 |
|
---|
719 | #ifdef TESTING
|
---|
720 |
|
---|
721 | static char * const bunzip_errors[]={NULL,"Bad file checksum","Not bzip data",
|
---|
722 | "Unexpected input EOF","Unexpected output EOF","Data error",
|
---|
723 | "Out of memory","Obsolete (pre 0.9.5) bzip format not supported."};
|
---|
724 |
|
---|
725 | /* Dumb little test thing, decompress stdin to stdout */
|
---|
726 | int main(int argc, char *argv[])
|
---|
727 | {
|
---|
728 | int i=uncompressStream(0,1);
|
---|
729 | char c;
|
---|
730 |
|
---|
731 | if(i) fprintf(stderr,"%s\n", bunzip_errors[-i]);
|
---|
732 | else if(read(0,&c,1)) fprintf(stderr,"Trailing garbage ignored\n");
|
---|
733 | return -i;
|
---|
734 | }
|
---|
735 | #endif
|
---|