| 1 | /* unlzh.c -- decompress files in SCO compress -H (LZH) format.
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| 2 | * The code in this file is directly derived from the public domain 'ar002'
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| 3 | * written by Haruhiko Okumura.
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| 4 | */
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| 5 |
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| 6 | #ifdef RCSID
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| 7 | static char rcsid[] = "$Id: unlzh.c,v 1.4 2006/11/20 08:40:34 eggert Exp $";
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| 8 | #endif
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| 9 |
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| 10 | #include <config.h>
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| 11 | #include <stdio.h>
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| 12 |
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| 13 | #include "tailor.h"
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| 14 | #include "gzip.h"
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| 15 | #include "lzw.h" /* just for consistency checking */
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| 16 |
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| 17 | /* decode.c */
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| 18 |
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| 19 | local unsigned decode OF((unsigned count, uch buffer[]));
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| 20 | local void decode_start OF((void));
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| 21 |
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| 22 | /* huf.c */
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| 23 | local void huf_decode_start OF((void));
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| 24 | local unsigned decode_c OF((void));
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| 25 | local unsigned decode_p OF((void));
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| 26 | local void read_pt_len OF((int nn, int nbit, int i_special));
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| 27 | local void read_c_len OF((void));
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| 28 |
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| 29 | /* io.c */
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| 30 | local void fillbuf OF((int n));
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| 31 | local unsigned getbits OF((int n));
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| 32 | local void init_getbits OF((void));
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| 33 |
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| 34 | /* maketbl.c */
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| 35 |
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| 36 | local void make_table OF((int nchar, uch bitlen[],
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| 37 | int tablebits, ush table[]));
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| 38 |
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| 39 |
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| 40 | #define DICBIT 13 /* 12(-lh4-) or 13(-lh5-) */
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| 41 | #define DICSIZ ((unsigned) 1 << DICBIT)
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| 42 |
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| 43 | #ifndef CHAR_BIT
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| 44 | # define CHAR_BIT 8
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| 45 | #endif
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| 46 |
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| 47 | #ifndef UCHAR_MAX
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| 48 | # define UCHAR_MAX 255
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| 49 | #endif
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| 50 |
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| 51 | #define BITBUFSIZ (CHAR_BIT * 2 * sizeof(char))
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| 52 | /* Do not use CHAR_BIT * sizeof(bitbuf), does not work on machines
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| 53 | * for which short is not on 16 bits (Cray).
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| 54 | */
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| 55 |
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| 56 | /* encode.c and decode.c */
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| 57 |
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| 58 | #define MAXMATCH 256 /* formerly F (not more than UCHAR_MAX + 1) */
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| 59 | #define THRESHOLD 3 /* choose optimal value */
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| 60 |
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| 61 | /* huf.c */
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| 62 |
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| 63 | #define NC (UCHAR_MAX + MAXMATCH + 2 - THRESHOLD)
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| 64 | /* alphabet = {0, 1, 2, ..., NC - 1} */
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| 65 | #define CBIT 9 /* $\lfloor \log_2 NC \rfloor + 1$ */
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| 66 | #define CODE_BIT 16 /* codeword length */
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| 67 |
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| 68 | #define NP (DICBIT + 1)
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| 69 | #define NT (CODE_BIT + 3)
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| 70 | #define PBIT 4 /* smallest integer such that (1U << PBIT) > NP */
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| 71 | #define TBIT 5 /* smallest integer such that (1U << TBIT) > NT */
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| 72 | #define NPT (1 << TBIT)
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| 73 |
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| 74 | /* local ush left[2 * NC - 1]; */
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| 75 | /* local ush right[2 * NC - 1]; */
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| 76 | #define left prev
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| 77 | #define right head
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| 78 | #if NC > (1<<(BITS-2))
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| 79 | error cannot overlay left+right and prev
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| 80 | #endif
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| 81 |
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| 82 | /* local uch c_len[NC]; */
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| 83 | #define c_len outbuf
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| 84 | #if NC > OUTBUFSIZ
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| 85 | error cannot overlay c_len and outbuf
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| 86 | #endif
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| 87 |
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| 88 | local uch pt_len[NPT];
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| 89 | local unsigned blocksize;
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| 90 | local ush pt_table[256];
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| 91 |
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| 92 | /* local ush c_table[4096]; */
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| 93 | #define c_table d_buf
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| 94 | #if (DIST_BUFSIZE-1) < 4095
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| 95 | error cannot overlay c_table and d_buf
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| 96 | #endif
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| 97 |
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| 98 | /***********************************************************
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| 99 | io.c -- input/output
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| 100 | ***********************************************************/
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| 101 |
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| 102 | local ush bitbuf;
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| 103 | local unsigned subbitbuf;
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| 104 | local int bitcount;
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| 105 |
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| 106 | local void fillbuf(n) /* Shift bitbuf n bits left, read n bits */
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| 107 | int n;
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| 108 | {
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| 109 | bitbuf <<= n;
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| 110 | while (n > bitcount) {
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| 111 | bitbuf |= subbitbuf << (n -= bitcount);
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| 112 | subbitbuf = (unsigned)try_byte();
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| 113 | if ((int)subbitbuf == EOF) subbitbuf = 0;
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| 114 | bitcount = CHAR_BIT;
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| 115 | }
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| 116 | bitbuf |= subbitbuf >> (bitcount -= n);
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| 117 | }
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| 118 |
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| 119 | local unsigned getbits(n)
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| 120 | int n;
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| 121 | {
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| 122 | unsigned x;
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| 123 |
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| 124 | x = bitbuf >> (BITBUFSIZ - n); fillbuf(n);
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| 125 | return x;
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| 126 | }
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| 127 |
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| 128 | local void init_getbits()
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| 129 | {
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| 130 | bitbuf = 0; subbitbuf = 0; bitcount = 0;
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| 131 | fillbuf(BITBUFSIZ);
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| 132 | }
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| 133 |
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| 134 | /***********************************************************
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| 135 | maketbl.c -- make table for decoding
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| 136 | ***********************************************************/
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| 137 |
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| 138 | local void make_table(nchar, bitlen, tablebits, table)
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| 139 | int nchar;
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| 140 | uch bitlen[];
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| 141 | int tablebits;
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| 142 | ush table[];
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| 143 | {
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| 144 | ush count[17], weight[17], start[18], *p;
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| 145 | unsigned i, k, len, ch, jutbits, avail, nextcode, mask;
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| 146 |
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| 147 | for (i = 1; i <= 16; i++) count[i] = 0;
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| 148 | for (i = 0; i < (unsigned)nchar; i++) count[bitlen[i]]++;
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| 149 |
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| 150 | start[1] = 0;
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| 151 | for (i = 1; i <= 16; i++)
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| 152 | start[i + 1] = start[i] + (count[i] << (16 - i));
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| 153 | if ((start[17] & 0xffff) != 0)
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| 154 | gzip_error ("Bad table\n");
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| 155 |
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| 156 | jutbits = 16 - tablebits;
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| 157 | for (i = 1; i <= (unsigned)tablebits; i++) {
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| 158 | start[i] >>= jutbits;
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| 159 | weight[i] = (unsigned) 1 << (tablebits - i);
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| 160 | }
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| 161 | while (i <= 16) {
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| 162 | weight[i] = (unsigned) 1 << (16 - i);
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| 163 | i++;
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| 164 | }
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| 165 |
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| 166 | i = start[tablebits + 1] >> jutbits;
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| 167 | if (i != 0) {
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| 168 | k = 1 << tablebits;
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| 169 | while (i != k) table[i++] = 0;
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| 170 | }
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| 171 |
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| 172 | avail = nchar;
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| 173 | mask = (unsigned) 1 << (15 - tablebits);
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| 174 | for (ch = 0; ch < (unsigned)nchar; ch++) {
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| 175 | if ((len = bitlen[ch]) == 0) continue;
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| 176 | nextcode = start[len] + weight[len];
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| 177 | if (len <= (unsigned)tablebits) {
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| 178 | if ((unsigned) 1 << tablebits < nextcode)
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| 179 | gzip_error ("Bad table\n");
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| 180 | for (i = start[len]; i < nextcode; i++) table[i] = ch;
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| 181 | } else {
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| 182 | k = start[len];
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| 183 | p = &table[k >> jutbits];
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| 184 | i = len - tablebits;
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| 185 | while (i != 0) {
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| 186 | if (*p == 0) {
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| 187 | right[avail] = left[avail] = 0;
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| 188 | *p = avail++;
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| 189 | }
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| 190 | if (k & mask) p = &right[*p];
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| 191 | else p = &left[*p];
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| 192 | k <<= 1; i--;
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| 193 | }
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| 194 | *p = ch;
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| 195 | }
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| 196 | start[len] = nextcode;
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| 197 | }
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| 198 | }
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| 199 |
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| 200 | /***********************************************************
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| 201 | huf.c -- static Huffman
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| 202 | ***********************************************************/
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| 203 |
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| 204 | local void read_pt_len(nn, nbit, i_special)
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| 205 | int nn;
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| 206 | int nbit;
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| 207 | int i_special;
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| 208 | {
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| 209 | int i, c, n;
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| 210 | unsigned mask;
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| 211 |
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| 212 | n = getbits(nbit);
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| 213 | if (n == 0) {
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| 214 | c = getbits(nbit);
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| 215 | for (i = 0; i < nn; i++) pt_len[i] = 0;
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| 216 | for (i = 0; i < 256; i++) pt_table[i] = c;
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| 217 | } else {
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| 218 | i = 0;
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| 219 | while (i < n) {
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| 220 | c = bitbuf >> (BITBUFSIZ - 3);
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| 221 | if (c == 7) {
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| 222 | mask = (unsigned) 1 << (BITBUFSIZ - 1 - 3);
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| 223 | while (mask & bitbuf) { mask >>= 1; c++; }
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| 224 | if (16 < c)
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| 225 | gzip_error ("Bad table\n");
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| 226 | }
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| 227 | fillbuf((c < 7) ? 3 : c - 3);
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| 228 | pt_len[i++] = c;
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| 229 | if (i == i_special) {
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| 230 | c = getbits(2);
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| 231 | while (--c >= 0) pt_len[i++] = 0;
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| 232 | }
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| 233 | }
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| 234 | while (i < nn) pt_len[i++] = 0;
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| 235 | make_table(nn, pt_len, 8, pt_table);
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| 236 | }
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| 237 | }
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| 238 |
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| 239 | local void read_c_len()
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| 240 | {
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| 241 | int i, c, n;
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| 242 | unsigned mask;
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| 243 |
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| 244 | n = getbits(CBIT);
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| 245 | if (n == 0) {
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| 246 | c = getbits(CBIT);
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| 247 | for (i = 0; i < NC; i++) c_len[i] = 0;
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| 248 | for (i = 0; i < 4096; i++) c_table[i] = c;
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| 249 | } else {
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| 250 | i = 0;
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| 251 | while (i < n) {
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| 252 | c = pt_table[bitbuf >> (BITBUFSIZ - 8)];
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| 253 | if (c >= NT) {
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| 254 | mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
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| 255 | do {
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| 256 | if (bitbuf & mask) c = right[c];
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| 257 | else c = left [c];
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| 258 | mask >>= 1;
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| 259 | } while (c >= NT);
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| 260 | }
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| 261 | fillbuf((int) pt_len[c]);
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| 262 | if (c <= 2) {
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| 263 | if (c == 0) c = 1;
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| 264 | else if (c == 1) c = getbits(4) + 3;
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| 265 | else c = getbits(CBIT) + 20;
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| 266 | while (--c >= 0) c_len[i++] = 0;
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| 267 | } else c_len[i++] = c - 2;
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| 268 | }
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| 269 | while (i < NC) c_len[i++] = 0;
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| 270 | make_table(NC, c_len, 12, c_table);
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| 271 | }
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| 272 | }
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| 273 |
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| 274 | local unsigned decode_c()
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| 275 | {
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| 276 | unsigned j, mask;
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| 277 |
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| 278 | if (blocksize == 0) {
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| 279 | blocksize = getbits(16);
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| 280 | if (blocksize == 0) {
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| 281 | return NC; /* end of file */
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| 282 | }
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| 283 | read_pt_len(NT, TBIT, 3);
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| 284 | read_c_len();
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| 285 | read_pt_len(NP, PBIT, -1);
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| 286 | }
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| 287 | blocksize--;
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| 288 | j = c_table[bitbuf >> (BITBUFSIZ - 12)];
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| 289 | if (j >= NC) {
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| 290 | mask = (unsigned) 1 << (BITBUFSIZ - 1 - 12);
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| 291 | do {
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| 292 | if (bitbuf & mask) j = right[j];
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| 293 | else j = left [j];
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| 294 | mask >>= 1;
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| 295 | } while (j >= NC);
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| 296 | }
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| 297 | fillbuf((int) c_len[j]);
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| 298 | return j;
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| 299 | }
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| 300 |
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| 301 | local unsigned decode_p()
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| 302 | {
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| 303 | unsigned j, mask;
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| 304 |
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| 305 | j = pt_table[bitbuf >> (BITBUFSIZ - 8)];
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| 306 | if (j >= NP) {
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| 307 | mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
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| 308 | do {
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| 309 | if (bitbuf & mask) j = right[j];
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| 310 | else j = left [j];
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| 311 | mask >>= 1;
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| 312 | } while (j >= NP);
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| 313 | }
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| 314 | fillbuf((int) pt_len[j]);
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| 315 | if (j != 0) j = ((unsigned) 1 << (j - 1)) + getbits((int) (j - 1));
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| 316 | return j;
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| 317 | }
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| 318 |
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| 319 | local void huf_decode_start()
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| 320 | {
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| 321 | init_getbits(); blocksize = 0;
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| 322 | }
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| 323 |
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| 324 | /***********************************************************
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| 325 | decode.c
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| 326 | ***********************************************************/
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| 327 |
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| 328 | local int j; /* remaining bytes to copy */
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| 329 | local int done; /* set at end of input */
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| 330 |
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| 331 | local void decode_start()
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| 332 | {
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| 333 | huf_decode_start();
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| 334 | j = 0;
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| 335 | done = 0;
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| 336 | }
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| 337 |
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| 338 | /* Decode the input and return the number of decoded bytes put in buffer
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| 339 | */
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| 340 | local unsigned decode(count, buffer)
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| 341 | unsigned count;
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| 342 | uch buffer[];
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| 343 | /* The calling function must keep the number of
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| 344 | bytes to be processed. This function decodes
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| 345 | either 'count' bytes or 'DICSIZ' bytes, whichever
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| 346 | is smaller, into the array 'buffer[]' of size
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| 347 | 'DICSIZ' or more.
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| 348 | Call decode_start() once for each new file
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| 349 | before calling this function.
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| 350 | */
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| 351 | {
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| 352 | local unsigned i;
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| 353 | unsigned r, c;
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| 354 |
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| 355 | r = 0;
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| 356 | while (--j >= 0) {
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| 357 | buffer[r] = buffer[i];
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| 358 | i = (i + 1) & (DICSIZ - 1);
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| 359 | if (++r == count) return r;
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| 360 | }
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| 361 | for ( ; ; ) {
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| 362 | c = decode_c();
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| 363 | if (c == NC) {
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| 364 | done = 1;
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| 365 | return r;
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| 366 | }
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| 367 | if (c <= UCHAR_MAX) {
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| 368 | buffer[r] = c;
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| 369 | if (++r == count) return r;
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| 370 | } else {
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| 371 | j = c - (UCHAR_MAX + 1 - THRESHOLD);
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| 372 | i = (r - decode_p() - 1) & (DICSIZ - 1);
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| 373 | while (--j >= 0) {
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| 374 | buffer[r] = buffer[i];
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| 375 | i = (i + 1) & (DICSIZ - 1);
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| 376 | if (++r == count) return r;
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| 377 | }
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| 378 | }
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| 379 | }
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| 380 | }
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| 381 |
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| 382 |
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| 383 | /* ===========================================================================
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| 384 | * Unlzh in to out. Return OK or ERROR.
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| 385 | */
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| 386 | int unlzh(in, out)
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| 387 | int in;
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| 388 | int out;
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| 389 | {
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| 390 | unsigned n;
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| 391 | ifd = in;
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| 392 | ofd = out;
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| 393 |
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| 394 | decode_start();
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| 395 | while (!done) {
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| 396 | n = decode((unsigned) DICSIZ, window);
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| 397 | if (!test && n > 0) {
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| 398 | write_buf(out, (char*)window, n);
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| 399 | }
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| 400 | }
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| 401 | return OK;
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| 402 | }
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