[1770] | 1 | /* vi: set sw=4 ts=4: */
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[821] | 2 | #include "libbb.h"
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| 3 |
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| 4 | /* uncompress for busybox -- (c) 2002 Robert Griebl
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| 5 | *
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| 6 | * based on the original compress42.c source
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| 7 | * (see disclaimer below)
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| 8 | */
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| 9 |
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| 10 | /* (N)compress42.c - File compression ala IEEE Computer, Mar 1992.
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| 11 | *
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| 12 | * Authors:
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| 13 | * Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
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| 14 | * Jim McKie (decvax!mcvax!jim)
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| 15 | * Steve Davies (decvax!vax135!petsd!peora!srd)
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| 16 | * Ken Turkowski (decvax!decwrl!turtlevax!ken)
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| 17 | * James A. Woods (decvax!ihnp4!ames!jaw)
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| 18 | * Joe Orost (decvax!vax135!petsd!joe)
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| 19 | * Dave Mack (csu@alembic.acs.com)
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| 20 | * Peter Jannesen, Network Communication Systems
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| 21 | * (peter@ncs.nl)
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| 22 | *
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| 23 | * marc@suse.de : a small security fix for a buffer overflow
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| 24 | *
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| 25 | * [... History snipped ...]
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| 26 | *
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| 27 | */
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| 28 |
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| 29 | /* Default input buffer size */
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| 30 | #define IBUFSIZ 2048
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| 31 |
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| 32 | /* Default output buffer size */
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| 33 | #define OBUFSIZ 2048
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| 34 |
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| 35 | /* Defines for third byte of header */
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[1770] | 36 | #define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */
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| 37 | /* Masks 0x20 and 0x40 are free. */
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| 38 | /* I think 0x20 should mean that there is */
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| 39 | /* a fourth header byte (for expansion). */
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| 40 | #define BLOCK_MODE 0x80 /* Block compression if table is full and */
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| 41 | /* compression rate is dropping flush tables */
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| 42 | /* the next two codes should not be changed lightly, as they must not */
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| 43 | /* lie within the contiguous general code space. */
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| 44 | #define FIRST 257 /* first free entry */
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| 45 | #define CLEAR 256 /* table clear output code */
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[821] | 46 |
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[1770] | 47 | #define INIT_BITS 9 /* initial number of bits/code */
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[821] | 48 |
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| 49 |
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| 50 | /* machine variants which require cc -Dmachine: pdp11, z8000, DOS */
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[1770] | 51 | #define HBITS 17 /* 50% occupancy */
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| 52 | #define HSIZE (1<<HBITS)
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| 53 | #define HMASK (HSIZE-1) /* unused */
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| 54 | #define HPRIME 9941 /* unused */
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| 55 | #define BITS 16
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| 56 | #define BITS_STR "16"
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| 57 | #undef MAXSEG_64K /* unused */
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| 58 | #define MAXCODE(n) (1L << (n))
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[821] | 59 |
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[1770] | 60 | #define htabof(i) htab[i]
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| 61 | #define codetabof(i) codetab[i]
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| 62 | #define tab_prefixof(i) codetabof(i)
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| 63 | #define tab_suffixof(i) ((unsigned char *)(htab))[i]
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| 64 | #define de_stack ((unsigned char *)&(htab[HSIZE-1]))
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| 65 | #define clear_tab_prefixof() memset(codetab, 0, 256)
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[821] | 66 |
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| 67 | /*
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| 68 | * Decompress stdin to stdout. This routine adapts to the codes in the
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| 69 | * file building the "string" table on-the-fly; requiring no table to
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[1770] | 70 | * be stored in the compressed file.
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[821] | 71 | */
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| 72 |
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[1770] | 73 | USE_DESKTOP(long long) int
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| 74 | uncompress(int fd_in, int fd_out)
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[821] | 75 | {
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[1770] | 76 | USE_DESKTOP(long long total_written = 0;)
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| 77 | USE_DESKTOP(long long) int retval = -1;
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[821] | 78 | unsigned char *stackp;
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[1770] | 79 | long code;
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[821] | 80 | int finchar;
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[1770] | 81 | long oldcode;
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| 82 | long incode;
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[821] | 83 | int inbits;
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| 84 | int posbits;
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| 85 | int outpos;
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| 86 | int insize;
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| 87 | int bitmask;
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[1770] | 88 | long free_ent;
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| 89 | long maxcode;
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| 90 | long maxmaxcode;
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[821] | 91 | int n_bits;
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| 92 | int rsize = 0;
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[1770] | 93 | unsigned char *inbuf; /* were eating insane amounts of stack - */
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| 94 | unsigned char *outbuf; /* bad for some embedded targets */
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| 95 | unsigned char *htab;
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| 96 | unsigned short *codetab;
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[821] | 97 |
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[1770] | 98 | /* Hmm, these were statics - why?! */
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| 99 | /* user settable max # bits/code */
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| 100 | int maxbits; /* = BITS; */
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| 101 | /* block compress mode -C compatible with 2.0 */
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| 102 | int block_mode; /* = BLOCK_MODE; */
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| 103 |
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| 104 | inbuf = xzalloc(IBUFSIZ + 64);
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| 105 | outbuf = xzalloc(OBUFSIZ + 2048);
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| 106 | htab = xzalloc(HSIZE); /* wsn't zeroed out before, maybe can xmalloc? */
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| 107 | codetab = xzalloc(HSIZE * sizeof(codetab[0]));
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| 108 |
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[821] | 109 | insize = 0;
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| 110 |
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[1770] | 111 | /* xread isn't good here, we have to return - caller may want
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| 112 | * to do some cleanup (e.g. delete incomplete unpacked file etc) */
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| 113 | if (full_read(fd_in, inbuf, 1) != 1) {
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| 114 | bb_error_msg("short read");
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| 115 | goto err;
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| 116 | }
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[821] | 117 |
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| 118 | maxbits = inbuf[0] & BIT_MASK;
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| 119 | block_mode = inbuf[0] & BLOCK_MODE;
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| 120 | maxmaxcode = MAXCODE(maxbits);
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| 121 |
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| 122 | if (maxbits > BITS) {
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[1770] | 123 | bb_error_msg("compressed with %d bits, can only handle "
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| 124 | BITS_STR" bits", maxbits);
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| 125 | goto err;
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[821] | 126 | }
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| 127 |
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[1770] | 128 | n_bits = INIT_BITS;
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| 129 | maxcode = MAXCODE(INIT_BITS) - 1;
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| 130 | bitmask = (1 << INIT_BITS) - 1;
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[821] | 131 | oldcode = -1;
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| 132 | finchar = 0;
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| 133 | outpos = 0;
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| 134 | posbits = 0 << 3;
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| 135 |
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| 136 | free_ent = ((block_mode) ? FIRST : 256);
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| 137 |
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| 138 | /* As above, initialize the first 256 entries in the table. */
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[1770] | 139 | /*clear_tab_prefixof(); - done by xzalloc */
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[821] | 140 |
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| 141 | for (code = 255; code >= 0; --code) {
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| 142 | tab_suffixof(code) = (unsigned char) code;
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| 143 | }
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| 144 |
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| 145 | do {
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[1770] | 146 | resetbuf:
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[821] | 147 | {
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| 148 | int i;
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| 149 | int e;
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| 150 | int o;
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| 151 |
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[1770] | 152 | o = posbits >> 3;
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| 153 | e = insize - o;
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[821] | 154 |
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| 155 | for (i = 0; i < e; ++i)
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| 156 | inbuf[i] = inbuf[i + o];
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| 157 |
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| 158 | insize = e;
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| 159 | posbits = 0;
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| 160 | }
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| 161 |
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[902] | 162 | if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) {
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[821] | 163 | rsize = safe_read(fd_in, inbuf + insize, IBUFSIZ);
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[1770] | 164 | //error check??
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[821] | 165 | insize += rsize;
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| 166 | }
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| 167 |
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| 168 | inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 :
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| 169 | (insize << 3) - (n_bits - 1));
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| 170 |
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| 171 | while (inbits > posbits) {
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| 172 | if (free_ent > maxcode) {
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| 173 | posbits =
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| 174 | ((posbits - 1) +
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| 175 | ((n_bits << 3) -
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| 176 | (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
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| 177 | ++n_bits;
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| 178 | if (n_bits == maxbits) {
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| 179 | maxcode = maxmaxcode;
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| 180 | } else {
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| 181 | maxcode = MAXCODE(n_bits) - 1;
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| 182 | }
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| 183 | bitmask = (1 << n_bits) - 1;
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| 184 | goto resetbuf;
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| 185 | }
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| 186 | {
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| 187 | unsigned char *p = &inbuf[posbits >> 3];
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| 188 |
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[1770] | 189 | code = ((((long) (p[0])) | ((long) (p[1]) << 8) |
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| 190 | ((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask;
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[821] | 191 | }
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| 192 | posbits += n_bits;
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| 193 |
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| 194 |
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| 195 | if (oldcode == -1) {
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[1770] | 196 | oldcode = code;
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| 197 | finchar = (int) oldcode;
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| 198 | outbuf[outpos++] = (unsigned char) finchar;
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[821] | 199 | continue;
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| 200 | }
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| 201 |
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| 202 | if (code == CLEAR && block_mode) {
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| 203 | clear_tab_prefixof();
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| 204 | free_ent = FIRST - 1;
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| 205 | posbits =
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| 206 | ((posbits - 1) +
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| 207 | ((n_bits << 3) -
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| 208 | (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
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[1770] | 209 | n_bits = INIT_BITS;
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| 210 | maxcode = MAXCODE(INIT_BITS) - 1;
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| 211 | bitmask = (1 << INIT_BITS) - 1;
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[821] | 212 | goto resetbuf;
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| 213 | }
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| 214 |
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| 215 | incode = code;
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| 216 | stackp = de_stack;
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| 217 |
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| 218 | /* Special case for KwKwK string. */
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| 219 | if (code >= free_ent) {
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| 220 | if (code > free_ent) {
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| 221 | unsigned char *p;
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| 222 |
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| 223 | posbits -= n_bits;
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| 224 | p = &inbuf[posbits >> 3];
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| 225 |
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| 226 | bb_error_msg
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| 227 | ("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)",
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| 228 | insize, posbits, p[-1], p[0], p[1], p[2], p[3],
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| 229 | (posbits & 07));
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| 230 | bb_error_msg("uncompress: corrupt input");
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[1770] | 231 | goto err;
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[821] | 232 | }
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| 233 |
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| 234 | *--stackp = (unsigned char) finchar;
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| 235 | code = oldcode;
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| 236 | }
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| 237 |
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| 238 | /* Generate output characters in reverse order */
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[1770] | 239 | while ((long) code >= (long) 256) {
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[821] | 240 | *--stackp = tab_suffixof(code);
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| 241 | code = tab_prefixof(code);
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| 242 | }
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| 243 |
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[1770] | 244 | finchar = tab_suffixof(code);
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| 245 | *--stackp = (unsigned char) finchar;
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[821] | 246 |
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| 247 | /* And put them out in forward order */
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| 248 | {
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| 249 | int i;
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| 250 |
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[1770] | 251 | i = de_stack - stackp;
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| 252 | if (outpos + i >= OBUFSIZ) {
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[821] | 253 | do {
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| 254 | if (i > OBUFSIZ - outpos) {
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| 255 | i = OBUFSIZ - outpos;
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| 256 | }
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| 257 |
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| 258 | if (i > 0) {
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| 259 | memcpy(outbuf + outpos, stackp, i);
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| 260 | outpos += i;
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| 261 | }
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| 262 |
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| 263 | if (outpos >= OBUFSIZ) {
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[1770] | 264 | full_write(fd_out, outbuf, outpos);
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| 265 | //error check??
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| 266 | USE_DESKTOP(total_written += outpos;)
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[821] | 267 | outpos = 0;
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| 268 | }
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| 269 | stackp += i;
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[1770] | 270 | i = de_stack - stackp;
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| 271 | } while (i > 0);
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[821] | 272 | } else {
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| 273 | memcpy(outbuf + outpos, stackp, i);
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| 274 | outpos += i;
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| 275 | }
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| 276 | }
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| 277 |
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| 278 | /* Generate the new entry. */
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[1770] | 279 | code = free_ent;
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| 280 | if (code < maxmaxcode) {
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[821] | 281 | tab_prefixof(code) = (unsigned short) oldcode;
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| 282 | tab_suffixof(code) = (unsigned char) finchar;
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| 283 | free_ent = code + 1;
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| 284 | }
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| 285 |
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| 286 | /* Remember previous code. */
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| 287 | oldcode = incode;
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| 288 | }
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| 289 |
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| 290 | } while (rsize > 0);
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| 291 |
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| 292 | if (outpos > 0) {
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[1770] | 293 | full_write(fd_out, outbuf, outpos);
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| 294 | //error check??
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| 295 | USE_DESKTOP(total_written += outpos;)
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[821] | 296 | }
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| 297 |
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[1770] | 298 | retval = USE_DESKTOP(total_written) + 0;
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| 299 | err:
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| 300 | free(inbuf);
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| 301 | free(outbuf);
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| 302 | free(htab);
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| 303 | free(codetab);
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| 304 | return retval;
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[821] | 305 | }
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