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293 lines
7.2 KiB
C
293 lines
7.2 KiB
C
/* vi: set sw=4 ts=4: */
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#include "libbb.h"
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/* uncompress for busybox -- (c) 2002 Robert Griebl
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*
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* based on the original compress42.c source
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* (see disclaimer below)
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*/
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/* (N)compress42.c - File compression ala IEEE Computer, Mar 1992.
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*
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* Authors:
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* Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
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* Jim McKie (decvax!mcvax!jim)
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* Steve Davies (decvax!vax135!petsd!peora!srd)
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* Ken Turkowski (decvax!decwrl!turtlevax!ken)
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* James A. Woods (decvax!ihnp4!ames!jaw)
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* Joe Orost (decvax!vax135!petsd!joe)
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* Dave Mack (csu@alembic.acs.com)
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* Peter Jannesen, Network Communication Systems
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* (peter@ncs.nl)
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*
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* marc@suse.de : a small security fix for a buffer overflow
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*
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* [... History snipped ...]
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*
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*/
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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/* Default input buffer size */
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#define IBUFSIZ 2048
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/* Default output buffer size */
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#define OBUFSIZ 2048
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/* Defines for third byte of header */
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#define MAGIC_1 (char_type)'\037' /* First byte of compressed file */
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#define MAGIC_2 (char_type)'\235' /* Second byte of compressed file */
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#define BIT_MASK 0x1f /* Mask for 'number of compresssion bits' */
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/* Masks 0x20 and 0x40 are free. */
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/* I think 0x20 should mean that there is */
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/* a fourth header byte (for expansion). */
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#define BLOCK_MODE 0x80 /* Block compresssion if table is full and */
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/* compression rate is dropping flush tables */
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/* the next two codes should not be changed lightly, as they must not */
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/* lie within the contiguous general code space. */
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#define FIRST 257 /* first free entry */
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#define CLEAR 256 /* table clear output code */
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#define INIT_BITS 9 /* initial number of bits/code */
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/* machine variants which require cc -Dmachine: pdp11, z8000, DOS */
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#define FAST
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#define HBITS 17 /* 50% occupancy */
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#define HSIZE (1<<HBITS)
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#define HMASK (HSIZE-1)
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#define HPRIME 9941
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#define BITS 16
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#undef MAXSEG_64K
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#define MAXCODE(n) (1L << (n))
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/* Block compress mode -C compatible with 2.0 */
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static int block_mode = BLOCK_MODE;
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/* user settable max # bits/code */
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static int maxbits = BITS;
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#define htabof(i) htab[i]
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#define codetabof(i) codetab[i]
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#define tab_prefixof(i) codetabof(i)
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#define tab_suffixof(i) ((unsigned char *)(htab))[i]
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#define de_stack ((unsigned char *)&(htab[HSIZE-1]))
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#define clear_htab() memset(htab, -1, HSIZE)
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#define clear_tab_prefixof() memset(codetab, 0, 256);
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/*
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* Decompress stdin to stdout. This routine adapts to the codes in the
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* file building the "string" table on-the-fly; requiring no table to
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* be stored in the compressed file. The tables used herein are shared
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* with those of the compress() routine. See the definitions above.
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*/
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USE_DESKTOP(long long) int
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uncompress(int fd_in, int fd_out)
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{
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USE_DESKTOP(long long total_written = 0;)
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unsigned char *stackp;
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long int code;
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int finchar;
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long int oldcode;
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long int incode;
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int inbits;
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int posbits;
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int outpos;
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int insize;
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int bitmask;
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long int free_ent;
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long int maxcode;
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long int maxmaxcode;
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int n_bits;
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int rsize = 0;
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RESERVE_CONFIG_UBUFFER(inbuf, IBUFSIZ + 64);
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RESERVE_CONFIG_UBUFFER(outbuf, OBUFSIZ + 2048);
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unsigned char htab[HSIZE];
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unsigned short codetab[HSIZE];
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memset(inbuf, 0, IBUFSIZ + 64);
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memset(outbuf, 0, OBUFSIZ + 2048);
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insize = 0;
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inbuf[0] = xread_char(fd_in);
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maxbits = inbuf[0] & BIT_MASK;
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block_mode = inbuf[0] & BLOCK_MODE;
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maxmaxcode = MAXCODE(maxbits);
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if (maxbits > BITS) {
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bb_error_msg("compressed with %d bits, can only handle %d bits", maxbits,
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BITS);
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return -1;
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}
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maxcode = MAXCODE(n_bits = INIT_BITS) - 1;
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bitmask = (1 << n_bits) - 1;
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oldcode = -1;
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finchar = 0;
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outpos = 0;
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posbits = 0 << 3;
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free_ent = ((block_mode) ? FIRST : 256);
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/* As above, initialize the first 256 entries in the table. */
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clear_tab_prefixof();
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for (code = 255; code >= 0; --code) {
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tab_suffixof(code) = (unsigned char) code;
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}
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do {
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resetbuf:;
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{
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int i;
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int e;
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int o;
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e = insize - (o = (posbits >> 3));
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for (i = 0; i < e; ++i)
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inbuf[i] = inbuf[i + o];
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insize = e;
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posbits = 0;
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}
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if (insize < (int) (IBUFSIZ + 64) - IBUFSIZ) {
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rsize = safe_read(fd_in, inbuf + insize, IBUFSIZ);
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insize += rsize;
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}
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inbits = ((rsize > 0) ? (insize - insize % n_bits) << 3 :
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(insize << 3) - (n_bits - 1));
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while (inbits > posbits) {
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if (free_ent > maxcode) {
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posbits =
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((posbits - 1) +
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((n_bits << 3) -
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(posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
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++n_bits;
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if (n_bits == maxbits) {
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maxcode = maxmaxcode;
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} else {
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maxcode = MAXCODE(n_bits) - 1;
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}
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bitmask = (1 << n_bits) - 1;
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goto resetbuf;
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}
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{
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unsigned char *p = &inbuf[posbits >> 3];
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code = ((((long) (p[0])) | ((long) (p[1]) << 8) |
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((long) (p[2]) << 16)) >> (posbits & 0x7)) & bitmask;
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}
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posbits += n_bits;
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if (oldcode == -1) {
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oldcode = code;
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finchar = (int) oldcode;
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outbuf[outpos++] = (unsigned char) finchar;
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continue;
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}
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if (code == CLEAR && block_mode) {
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clear_tab_prefixof();
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free_ent = FIRST - 1;
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posbits =
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((posbits - 1) +
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((n_bits << 3) -
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(posbits - 1 + (n_bits << 3)) % (n_bits << 3)));
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maxcode = MAXCODE(n_bits = INIT_BITS) - 1;
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bitmask = (1 << n_bits) - 1;
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goto resetbuf;
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}
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incode = code;
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stackp = de_stack;
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/* Special case for KwKwK string. */
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if (code >= free_ent) {
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if (code > free_ent) {
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unsigned char *p;
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posbits -= n_bits;
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p = &inbuf[posbits >> 3];
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bb_error_msg
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("insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)",
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insize, posbits, p[-1], p[0], p[1], p[2], p[3],
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(posbits & 07));
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bb_error_msg("uncompress: corrupt input");
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return -1;
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}
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*--stackp = (unsigned char) finchar;
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code = oldcode;
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}
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/* Generate output characters in reverse order */
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while ((long int) code >= (long int) 256) {
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*--stackp = tab_suffixof(code);
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code = tab_prefixof(code);
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}
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*--stackp = (unsigned char) (finchar = tab_suffixof(code));
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/* And put them out in forward order */
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{
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int i;
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if (outpos + (i = (de_stack - stackp)) >= OBUFSIZ) {
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do {
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if (i > OBUFSIZ - outpos) {
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i = OBUFSIZ - outpos;
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}
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if (i > 0) {
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memcpy(outbuf + outpos, stackp, i);
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outpos += i;
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}
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if (outpos >= OBUFSIZ) {
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write(fd_out, outbuf, outpos);
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USE_DESKTOP(total_written += outpos;)
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outpos = 0;
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}
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stackp += i;
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} while ((i = (de_stack - stackp)) > 0);
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} else {
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memcpy(outbuf + outpos, stackp, i);
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outpos += i;
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}
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}
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/* Generate the new entry. */
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if ((code = free_ent) < maxmaxcode) {
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tab_prefixof(code) = (unsigned short) oldcode;
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tab_suffixof(code) = (unsigned char) finchar;
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free_ent = code + 1;
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}
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/* Remember previous code. */
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oldcode = incode;
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}
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} while (rsize > 0);
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if (outpos > 0) {
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write(fd_out, outbuf, outpos);
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USE_DESKTOP(total_written += outpos;)
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}
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RELEASE_CONFIG_BUFFER(inbuf);
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RELEASE_CONFIG_BUFFER(outbuf);
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return USE_DESKTOP(total_written) + 0;
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}
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