94a6a956f0
(configurable) - When enabled an applet "uncompress" is also made available (oddname to gunzip) [the cvs add for this file got lost somehow...]
314 lines
7.2 KiB
C
314 lines
7.2 KiB
C
#include "config.h"
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#include "libbb.h"
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#ifdef CONFIG_FEATURE_UNCOMPRESS
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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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#define IBUFSIZ 2048 /* Defailt input buffer size */
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#define OBUFSIZ 2048 /* Default output buffer size */
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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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/*
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* machine variants which require cc -Dmachine: pdp11, z8000, DOS
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*/
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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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typedef long int code_int;
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typedef long int count_int;
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typedef long int cmp_code_int;
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typedef unsigned char char_type;
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#define MAXCODE(n) (1L << (n))
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int block_mode = BLOCK_MODE;/* Block compress mode -C compatible with 2.0*/
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int maxbits = BITS; /* user settable max # bits/code */
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int exit_code = -1; /* Exitcode of compress (-1 no file compressed) */
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char_type inbuf[IBUFSIZ+64]; /* Input buffer */
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char_type outbuf[OBUFSIZ+2048];/* Output buffer */
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count_int htab[HSIZE];
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unsigned short codetab[HSIZE];
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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) ((char_type *)(htab))[i]
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#define de_stack ((char_type *)&(htab[HSIZE-1]))
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#define clear_htab() memset(htab, -1, sizeof(htab))
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#define clear_tab_prefixof() memset(codetab, 0, 256);
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extern int uncompress ( FILE *, FILE * );
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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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int uncompress ( FILE * fdin, FILE * fdout )
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{
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char_type *stackp;
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code_int code;
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int finchar;
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code_int oldcode;
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code_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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code_int free_ent;
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code_int maxcode;
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code_int maxmaxcode;
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int n_bits;
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int rsize = 0;
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insize = 0;
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inbuf [0] = fgetc(fdin);
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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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{
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fprintf(stderr, "compressed with %d bits, can only handle %d bits\n", maxbits, BITS);
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return -1;
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}
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//fprintf(stderr, "Bits: %d, block_mode: %d\n", maxbits, block_mode );
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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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clear_tab_prefixof(); /* As above, initialize the first
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256 entries in the table. */
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for (code = 255 ; code >= 0 ; --code)
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tab_suffixof(code) = (char_type)code;
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do
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{
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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) sizeof(inbuf)-IBUFSIZ)
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{
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rsize = fread(inbuf+insize, 1,IBUFSIZ,fdin);
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if ( !rsize && ferror(fdin))
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return -1;
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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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{
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if (free_ent > maxcode)
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{
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posbits = ((posbits-1) + ((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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bitmask = (1<<n_bits)-1;
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goto resetbuf;
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}
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{
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char_type *p = &inbuf[posbits>>3];
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code = ((((long)(p[0]))|((long)(p[1])<<8)|((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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{
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outbuf[outpos++] = (char_type)(finchar = (int)(oldcode = code));
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continue;
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}
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if (code == CLEAR && block_mode)
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{
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clear_tab_prefixof();
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free_ent = FIRST - 1;
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posbits = ((posbits-1) + ((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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if (code >= free_ent) /* Special case for KwKwK string. */
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{
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if (code > free_ent)
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{
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char_type *p;
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posbits -= n_bits;
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p = &inbuf[posbits>>3];
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fprintf(stderr, "insize:%d posbits:%d inbuf:%02X %02X %02X %02X %02X (%d)\n", insize, posbits,
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p[-1],p[0],p[1],p[2],p[3], (posbits&07));
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fprintf(stderr, "uncompress: corrupt input\n");
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return -1;
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}
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*--stackp = (char_type)finchar;
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code = oldcode;
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}
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while ((cmp_code_int)code >= (cmp_code_int)256)
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{ /* Generate output characters in reverse order */
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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 = (char_type)(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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{
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do
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{
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if (i > OBUFSIZ-outpos) i = OBUFSIZ-outpos;
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if (i > 0)
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{
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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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{
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fwrite(outbuf, 1,outpos,fdout);
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outpos = 0;
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}
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stackp+= i;
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}
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while ((i = (de_stack-stackp)) > 0);
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}
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else
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{
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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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if ((code = free_ent) < maxmaxcode) /* Generate the new entry. */
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{
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tab_prefixof(code) = (unsigned short)oldcode;
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tab_suffixof(code) = (char_type)finchar;
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free_ent = code+1;
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}
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oldcode = incode; /* Remember previous code. */
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}
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}
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while (rsize > 0);
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if (outpos > 0)
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fwrite(outbuf, outpos,1, fdout);
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return 0;
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}
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#endif
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