[2725] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /* uncompress for busybox -- (c) 2002 Robert Griebl
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| 3 | *
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| 4 | * based on the original compress42.c source
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| 5 | * (see disclaimer below)
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| 6 | */
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| 7 |
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| 8 | /* (N)compress42.c - File compression ala IEEE Computer, Mar 1992.
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| 9 | *
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| 10 | * Authors:
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| 11 | * Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
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| 12 | * Jim McKie (decvax!mcvax!jim)
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| 13 | * Steve Davies (decvax!vax135!petsd!peora!srd)
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| 14 | * Ken Turkowski (decvax!decwrl!turtlevax!ken)
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| 15 | * James A. Woods (decvax!ihnp4!ames!jaw)
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| 16 | * Joe Orost (decvax!vax135!petsd!joe)
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| 17 | * Dave Mack (csu@alembic.acs.com)
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| 18 | * Peter Jannesen, Network Communication Systems
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| 19 | * (peter@ncs.nl)
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| 20 | *
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| 21 | * marc@suse.de : a small security fix for a buffer overflow
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| 22 | *
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| 23 | * [... History snipped ...]
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| 24 | *
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| 25 | */
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| 26 |
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| 27 | #include "libbb.h"
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[3232] | 28 | #include "bb_archive.h"
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[2725] | 29 |
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| 30 |
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| 31 | /* Default input buffer size */
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| 32 | #define IBUFSIZ 2048
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| 33 |
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| 34 | /* Default output buffer size */
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| 35 | #define OBUFSIZ 2048
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| 36 |
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| 37 | /* Defines for third byte of header */
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| 38 | #define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */
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| 39 | /* Masks 0x20 and 0x40 are free. */
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| 40 | /* I think 0x20 should mean that there is */
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| 41 | /* a fourth header byte (for expansion). */
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| 42 | #define BLOCK_MODE 0x80 /* Block compression if table is full and */
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| 43 | /* compression rate is dropping flush tables */
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| 44 | /* the next two codes should not be changed lightly, as they must not */
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| 45 | /* lie within the contiguous general code space. */
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| 46 | #define FIRST 257 /* first free entry */
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| 47 | #define CLEAR 256 /* table clear output code */
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| 48 |
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| 49 | #define INIT_BITS 9 /* initial number of bits/code */
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| 50 |
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| 51 |
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| 52 | /* machine variants which require cc -Dmachine: pdp11, z8000, DOS */
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| 53 | #define HBITS 17 /* 50% occupancy */
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| 54 | #define HSIZE (1<<HBITS)
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| 55 | #define HMASK (HSIZE-1) /* unused */
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| 56 | #define HPRIME 9941 /* unused */
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| 57 | #define BITS 16
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| 58 | #define BITS_STR "16"
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| 59 | #undef MAXSEG_64K /* unused */
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| 60 | #define MAXCODE(n) (1L << (n))
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| 61 |
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| 62 | #define htabof(i) htab[i]
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| 63 | #define codetabof(i) codetab[i]
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| 64 | #define tab_prefixof(i) codetabof(i)
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| 65 | #define tab_suffixof(i) ((unsigned char *)(htab))[i]
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| 66 | #define de_stack ((unsigned char *)&(htab[HSIZE-1]))
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| 67 | #define clear_tab_prefixof() memset(codetab, 0, 256)
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| 68 |
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| 69 | /*
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| 70 | * Decompress stdin to stdout. This routine adapts to the codes in the
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| 71 | * file building the "string" table on-the-fly; requiring no table to
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| 72 | * be stored in the compressed file.
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| 73 | */
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| 74 |
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| 75 | IF_DESKTOP(long long) int FAST_FUNC
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[3232] | 76 | unpack_Z_stream(transformer_aux_data_t *aux, int src_fd, int dst_fd)
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[2725] | 77 | {
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| 78 | IF_DESKTOP(long long total_written = 0;)
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| 79 | IF_DESKTOP(long long) int retval = -1;
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| 80 | unsigned char *stackp;
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| 81 | int finchar;
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| 82 | long oldcode;
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| 83 | long incode;
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| 84 | int inbits;
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| 85 | int posbits;
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| 86 | int outpos;
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| 87 | int insize;
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| 88 | int bitmask;
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| 89 | long free_ent;
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| 90 | long maxcode;
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| 91 | long maxmaxcode;
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| 92 | int n_bits;
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| 93 | int rsize = 0;
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| 94 | unsigned char *inbuf; /* were eating insane amounts of stack - */
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| 95 | unsigned char *outbuf; /* bad for some embedded targets */
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| 96 | unsigned char *htab;
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| 97 | unsigned short *codetab;
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| 98 |
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| 99 | /* Hmm, these were statics - why?! */
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| 100 | /* user settable max # bits/code */
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| 101 | int maxbits; /* = BITS; */
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| 102 | /* block compress mode -C compatible with 2.0 */
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| 103 | int block_mode; /* = BLOCK_MODE; */
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| 104 |
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[3232] | 105 | if (check_signature16(aux, src_fd, COMPRESS_MAGIC))
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| 106 | return -1;
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| 107 |
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[2725] | 108 | inbuf = xzalloc(IBUFSIZ + 64);
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| 109 | outbuf = xzalloc(OBUFSIZ + 2048);
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[3232] | 110 | htab = xzalloc(HSIZE); /* wasn't zeroed out before, maybe can xmalloc? */
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[2725] | 111 | codetab = xzalloc(HSIZE * sizeof(codetab[0]));
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| 112 |
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| 113 | insize = 0;
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| 114 |
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| 115 | /* xread isn't good here, we have to return - caller may want
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| 116 | * to do some cleanup (e.g. delete incomplete unpacked file etc) */
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[3232] | 117 | if (full_read(src_fd, inbuf, 1) != 1) {
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[2725] | 118 | bb_error_msg("short read");
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| 119 | goto err;
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| 120 | }
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| 121 |
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| 122 | maxbits = inbuf[0] & BIT_MASK;
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| 123 | block_mode = inbuf[0] & BLOCK_MODE;
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| 124 | maxmaxcode = MAXCODE(maxbits);
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| 125 |
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| 126 | if (maxbits > BITS) {
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| 127 | bb_error_msg("compressed with %d bits, can only handle "
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| 128 | BITS_STR" bits", maxbits);
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| 129 | goto err;
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| 130 | }
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| 131 |
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| 132 | n_bits = INIT_BITS;
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| 133 | maxcode = MAXCODE(INIT_BITS) - 1;
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| 134 | bitmask = (1 << INIT_BITS) - 1;
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| 135 | oldcode = -1;
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| 136 | finchar = 0;
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| 137 | outpos = 0;
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| 138 | posbits = 0 << 3;
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| 139 |
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| 140 | free_ent = ((block_mode) ? FIRST : 256);
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| 141 |
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| 142 | /* As above, initialize the first 256 entries in the table. */
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| 143 | /*clear_tab_prefixof(); - done by xzalloc */
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| 144 |
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[3232] | 145 | {
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| 146 | int i;
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| 147 | for (i = 255; i >= 0; --i)
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| 148 | tab_suffixof(i) = (unsigned char) i;
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[2725] | 149 | }
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| 150 |
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| 151 | do {
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| 152 | resetbuf:
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| 153 | {
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| 154 | int i;
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| 155 | int e;
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| 156 | int o;
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| 157 |
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| 158 | o = posbits >> 3;
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| 159 | e = insize - o;
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| 160 |
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| 161 | for (i = 0; i < e; ++i)
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| 162 | inbuf[i] = inbuf[i + o];
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| 163 |
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| 164 | insize = e;
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| 165 | posbits = 0;
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| 166 | }
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| 167 |
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| 168 | if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) {
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[3232] | 169 | rsize = safe_read(src_fd, inbuf + insize, IBUFSIZ);
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| 170 | if (rsize < 0)
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| 171 | bb_error_msg_and_die(bb_msg_read_error);
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[2725] | 172 | insize += rsize;
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| 173 | }
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| 174 |
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| 175 | inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 :
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| 176 | (insize << 3) - (n_bits - 1));
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| 177 |
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| 178 | while (inbits > posbits) {
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[3232] | 179 | long code;
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| 180 |
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[2725] | 181 | if (free_ent > maxcode) {
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| 182 | posbits =
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| 183 | ((posbits - 1) +
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| 184 | ((n_bits << 3) -
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| 185 | (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
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| 186 | ++n_bits;
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| 187 | if (n_bits == maxbits) {
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| 188 | maxcode = maxmaxcode;
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| 189 | } else {
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| 190 | maxcode = MAXCODE(n_bits) - 1;
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| 191 | }
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| 192 | bitmask = (1 << n_bits) - 1;
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| 193 | goto resetbuf;
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| 194 | }
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| 195 | {
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| 196 | unsigned char *p = &inbuf[posbits >> 3];
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[3232] | 197 | code = ((p[0]
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| 198 | | ((long) (p[1]) << 8)
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| 199 | | ((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask;
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[2725] | 200 | }
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| 201 | posbits += n_bits;
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| 202 |
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| 203 | if (oldcode == -1) {
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[3232] | 204 | if (code >= 256)
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| 205 | bb_error_msg_and_die("corrupted data"); /* %ld", code); */
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[2725] | 206 | oldcode = code;
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| 207 | finchar = (int) oldcode;
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| 208 | outbuf[outpos++] = (unsigned char) finchar;
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| 209 | continue;
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| 210 | }
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| 211 |
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| 212 | if (code == CLEAR && block_mode) {
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| 213 | clear_tab_prefixof();
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| 214 | free_ent = FIRST - 1;
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| 215 | posbits =
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| 216 | ((posbits - 1) +
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| 217 | ((n_bits << 3) -
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| 218 | (posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
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| 219 | n_bits = INIT_BITS;
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| 220 | maxcode = MAXCODE(INIT_BITS) - 1;
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| 221 | bitmask = (1 << INIT_BITS) - 1;
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| 222 | goto resetbuf;
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| 223 | }
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| 224 |
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| 225 | incode = code;
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| 226 | stackp = de_stack;
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| 227 |
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| 228 | /* Special case for KwKwK string. */
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| 229 | if (code >= free_ent) {
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| 230 | if (code > free_ent) {
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[3232] | 231 | /*
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[2725] | 232 | unsigned char *p;
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| 233 |
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| 234 | posbits -= n_bits;
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| 235 | p = &inbuf[posbits >> 3];
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| 236 | bb_error_msg
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| 237 | ("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)",
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[3232] | 238 | insize, posbits, p[-1], p[0], p[1], p[2], p[3],
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| 239 | (posbits & 07));
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| 240 | */
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[2725] | 241 | bb_error_msg("corrupted data");
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| 242 | goto err;
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| 243 | }
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| 244 |
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| 245 | *--stackp = (unsigned char) finchar;
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| 246 | code = oldcode;
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| 247 | }
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| 248 |
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| 249 | /* Generate output characters in reverse order */
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[3232] | 250 | while (code >= 256) {
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| 251 | if (stackp <= &htabof(0))
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| 252 | bb_error_msg_and_die("corrupted data");
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[2725] | 253 | *--stackp = tab_suffixof(code);
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| 254 | code = tab_prefixof(code);
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| 255 | }
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| 256 |
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| 257 | finchar = tab_suffixof(code);
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| 258 | *--stackp = (unsigned char) finchar;
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| 259 |
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| 260 | /* And put them out in forward order */
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| 261 | {
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| 262 | int i;
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| 263 |
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| 264 | i = de_stack - stackp;
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| 265 | if (outpos + i >= OBUFSIZ) {
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| 266 | do {
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| 267 | if (i > OBUFSIZ - outpos) {
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| 268 | i = OBUFSIZ - outpos;
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| 269 | }
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| 270 |
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| 271 | if (i > 0) {
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| 272 | memcpy(outbuf + outpos, stackp, i);
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| 273 | outpos += i;
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| 274 | }
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| 275 |
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| 276 | if (outpos >= OBUFSIZ) {
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[3232] | 277 | xwrite(dst_fd, outbuf, outpos);
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[2725] | 278 | IF_DESKTOP(total_written += outpos;)
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| 279 | outpos = 0;
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| 280 | }
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| 281 | stackp += i;
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| 282 | i = de_stack - stackp;
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| 283 | } while (i > 0);
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| 284 | } else {
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| 285 | memcpy(outbuf + outpos, stackp, i);
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| 286 | outpos += i;
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| 287 | }
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| 288 | }
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| 289 |
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| 290 | /* Generate the new entry. */
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[3232] | 291 | if (free_ent < maxmaxcode) {
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| 292 | tab_prefixof(free_ent) = (unsigned short) oldcode;
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| 293 | tab_suffixof(free_ent) = (unsigned char) finchar;
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| 294 | free_ent++;
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[2725] | 295 | }
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| 296 |
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| 297 | /* Remember previous code. */
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| 298 | oldcode = incode;
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| 299 | }
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| 300 |
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| 301 | } while (rsize > 0);
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| 302 |
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| 303 | if (outpos > 0) {
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[3232] | 304 | xwrite(dst_fd, outbuf, outpos);
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[2725] | 305 | IF_DESKTOP(total_written += outpos;)
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| 306 | }
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| 307 |
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| 308 | retval = IF_DESKTOP(total_written) + 0;
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| 309 | err:
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| 310 | free(inbuf);
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| 311 | free(outbuf);
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| 312 | free(htab);
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| 313 | free(codetab);
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| 314 | return retval;
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| 315 | }
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