2530 lines
78 KiB
C
2530 lines
78 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Gzip implementation for busybox
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*
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* Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
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*
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* Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
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* "this is a stripped down version of gzip I put into busybox, it does
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* only standard in to standard out with -9 compression. It also requires
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* the zcat module for some important functions."
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*
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* Adjusted further by Erik Andersen <andersen@codepoet.org> to support
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* files as well as stdin/stdout, and to generally behave itself wrt
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* command line handling.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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/* These defines are very important for BusyBox. Without these,
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* huge chunks of ram are pre-allocated making the BusyBox bss
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* size Freaking Huge(tm), which is a bad thing.*/
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#define SMALL_MEM
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#define DYN_ALLOC
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#include <stdlib.h>
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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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#include <errno.h>
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#include <sys/types.h>
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#include <signal.h>
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#include <utime.h>
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#include <ctype.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include <time.h>
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#include "busybox.h"
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typedef unsigned char uch;
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typedef unsigned short ush;
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typedef unsigned long ulg;
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/* Return codes from gzip */
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#define OK 0
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#define ERROR 1
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#define WARNING 2
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/* Compression methods (see algorithm.doc) */
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/* Only STORED and DEFLATED are supported by this BusyBox module */
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#define STORED 0
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/* methods 4 to 7 reserved */
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#define DEFLATED 8
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/* To save memory for 16 bit systems, some arrays are overlaid between
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* the various modules:
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* deflate: prev+head window d_buf l_buf outbuf
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* unlzw: tab_prefix tab_suffix stack inbuf outbuf
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* For compression, input is done in window[]. For decompression, output
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* is done in window except for unlzw.
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*/
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#ifndef INBUFSIZ
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# ifdef SMALL_MEM
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# define INBUFSIZ 0x2000 /* input buffer size */
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# else
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# define INBUFSIZ 0x8000 /* input buffer size */
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# endif
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#endif
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#define INBUF_EXTRA 64 /* required by unlzw() */
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#ifndef OUTBUFSIZ
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# ifdef SMALL_MEM
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# define OUTBUFSIZ 8192 /* output buffer size */
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# else
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# define OUTBUFSIZ 16384 /* output buffer size */
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# endif
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#endif
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#define OUTBUF_EXTRA 2048 /* required by unlzw() */
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#ifndef DIST_BUFSIZE
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# ifdef SMALL_MEM
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# define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
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# else
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# define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
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# endif
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#endif
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#ifdef DYN_ALLOC
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# define DECLARE(type, array, size) static type * array
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# define ALLOC(type, array, size) { \
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array = (type*)xcalloc((size_t)(((size)+1L)/2), 2*sizeof(type)); \
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}
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# define FREE(array) {free(array), array=NULL;}
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#else
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# define DECLARE(type, array, size) static type array[size]
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# define ALLOC(type, array, size)
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# define FREE(array)
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#endif
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#define tab_suffix window
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#define tab_prefix prev /* hash link (see deflate.c) */
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#define head (prev+WSIZE) /* hash head (see deflate.c) */
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static long bytes_in; /* number of input bytes */
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#define isize bytes_in
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/* for compatibility with old zip sources (to be cleaned) */
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typedef int file_t; /* Do not use stdio */
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#define NO_FILE (-1) /* in memory compression */
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#define PACK_MAGIC "\037\036" /* Magic header for packed files */
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#define GZIP_MAGIC "\037\213" /* Magic header for gzip files, 1F 8B */
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#define OLD_GZIP_MAGIC "\037\236" /* Magic header for gzip 0.5 = freeze 1.x */
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#define LZH_MAGIC "\037\240" /* Magic header for SCO LZH Compress files */
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#define PKZIP_MAGIC "\120\113\003\004" /* Magic header for pkzip files */
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/* gzip flag byte */
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#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
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#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
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#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
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#define ORIG_NAME 0x08 /* bit 3 set: original file name present */
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#define COMMENT 0x10 /* bit 4 set: file comment present */
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#define RESERVED 0xC0 /* bit 6,7: reserved */
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/* internal file attribute */
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#define UNKNOWN 0xffff
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#define BINARY 0
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#define ASCII 1
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#ifndef WSIZE
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# define WSIZE 0x8000 /* window size--must be a power of two, and */
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#endif /* at least 32K for zip's deflate method */
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#define MIN_MATCH 3
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#define MAX_MATCH 258
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/* The minimum and maximum match lengths */
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#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
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/* Minimum amount of lookahead, except at the end of the input file.
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* See deflate.c for comments about the MIN_MATCH+1.
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*/
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#define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
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/* In order to simplify the code, particularly on 16 bit machines, match
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* distances are limited to MAX_DIST instead of WSIZE.
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*/
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/* put_byte is used for the compressed output */
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#define put_byte(c) {outbuf[outcnt++]=(uch)(c); if (outcnt==OUTBUFSIZ)\
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flush_outbuf();}
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/* Output a 32 bit value to the bit stream, lsb first */
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#if 0
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#define put_long(n) { \
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put_short((n) & 0xffff); \
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put_short(((ulg)(n)) >> 16); \
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}
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#endif
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#define seekable() 0 /* force sequential output */
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#define translate_eol 0 /* no option -a yet */
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/* Diagnostic functions */
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#ifdef DEBUG
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# define Assert(cond,msg) {if(!(cond)) bb_error_msg(msg);}
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# define Trace(x) fprintf x
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# define Tracev(x) {if (verbose) fprintf x ;}
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# define Tracevv(x) {if (verbose>1) fprintf x ;}
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# define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
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# define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
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#else
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# define Assert(cond,msg)
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# define Trace(x)
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# define Tracev(x)
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# define Tracevv(x)
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# define Tracec(c,x)
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# define Tracecv(c,x)
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#endif
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#define WARN(msg) {if (!quiet) fprintf msg ; \
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if (exit_code == OK) exit_code = WARNING;}
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#ifndef MAX_PATH_LEN
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# define MAX_PATH_LEN 1024 /* max pathname length */
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#endif
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/* from zip.c: */
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static int zip(int in, int out);
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static int file_read(char *buf, unsigned size);
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/* from deflate.c */
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static void lm_init(ush * flags);
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static ulg deflate(void);
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/* from trees.c */
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static void ct_init(ush * attr, int *methodp);
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static int ct_tally(int dist, int lc);
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static ulg flush_block(char *buf, ulg stored_len, int eof);
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/* from bits.c */
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static void bi_init(file_t zipfile);
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static void send_bits(int value, int length);
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static unsigned bi_reverse(unsigned value, int length);
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static void bi_windup(void);
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static void copy_block(char *buf, unsigned len, int header);
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static int (*read_buf) (char *buf, unsigned size);
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/* from util.c: */
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static void flush_outbuf(void);
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/* lzw.h -- define the lzw functions.
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* Copyright (C) 1992-1993 Jean-loup Gailly.
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* This is free software; you can redistribute it and/or modify it under the
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* terms of the GNU General Public License, see the file COPYING.
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*/
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#if !defined(OF) && defined(lint)
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# include "gzip.h"
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#endif
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#ifndef BITS
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# define BITS 16
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#endif
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#define INIT_BITS 9 /* Initial number of bits per code */
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#define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
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/* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
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* It's a pity that old uncompress does not check bit 0x20. That makes
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* extension of the format actually undesirable because old compress
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* would just crash on the new format instead of giving a meaningful
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* error message. It does check the number of bits, but it's more
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* helpful to say "unsupported format, get a new version" than
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* "can only handle 16 bits".
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*/
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/* tailor.h -- target dependent definitions
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* Copyright (C) 1992-1993 Jean-loup Gailly.
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* This is free software; you can redistribute it and/or modify it under the
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* terms of the GNU General Public License, see the file COPYING.
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*/
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/* The target dependent definitions should be defined here only.
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* The target dependent functions should be defined in tailor.c.
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*/
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/* Common defaults */
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#ifndef OS_CODE
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# define OS_CODE 0x03 /* assume Unix */
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#endif
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#ifndef PATH_SEP
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# define PATH_SEP '/'
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#endif
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#ifndef OPTIONS_VAR
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# define OPTIONS_VAR "GZIP"
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#endif
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#ifndef Z_SUFFIX
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# define Z_SUFFIX ".gz"
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#endif
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#ifdef MAX_EXT_CHARS
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# define MAX_SUFFIX MAX_EXT_CHARS
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#else
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# define MAX_SUFFIX 30
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#endif
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/* global buffers */
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DECLARE(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
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DECLARE(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
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DECLARE(ush, d_buf, DIST_BUFSIZE);
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DECLARE(uch, window, 2L * WSIZE);
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DECLARE(ush, tab_prefix, 1L << BITS);
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static int foreground; /* set if program run in foreground */
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static int method = DEFLATED; /* compression method */
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static int exit_code = OK; /* program exit code */
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static int part_nb; /* number of parts in .gz file */
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static long time_stamp; /* original time stamp (modification time) */
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static long ifile_size; /* input file size, -1 for devices (debug only) */
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static char z_suffix[MAX_SUFFIX + 1]; /* default suffix (can be set with --suffix) */
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static int z_len; /* strlen(z_suffix) */
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static int ifd; /* input file descriptor */
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static int ofd; /* output file descriptor */
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static unsigned insize; /* valid bytes in inbuf */
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static unsigned outcnt; /* bytes in output buffer */
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/* Output a 16 bit value, lsb first */
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static void put_short(ush w)
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{
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if (outcnt < OUTBUFSIZ - 2) {
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outbuf[outcnt++] = (uch) ((w) & 0xff);
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outbuf[outcnt++] = (uch) ((ush) (w) >> 8);
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} else {
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put_byte((uch) ((w) & 0xff));
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put_byte((uch) ((ush) (w) >> 8));
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}
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}
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/* ========================================================================
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* Signal and error handler.
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*/
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static void abort_gzip(int ignored)
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{
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exit(ERROR);
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}
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/* ===========================================================================
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* Clear input and output buffers
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*/
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static void clear_bufs(void)
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{
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outcnt = 0;
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insize = 0;
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bytes_in = 0L;
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}
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/* ===========================================================================
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* Does the same as write(), but also handles partial pipe writes and checks
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* for error return.
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*/
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static void write_buf(int fd, void *buf, unsigned cnt)
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{
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unsigned n;
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while ((n = write(fd, buf, cnt)) != cnt) {
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if (n == (unsigned) (-1)) bb_error_msg_and_die("can't write");
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cnt -= n;
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buf = (void *) ((char *) buf + n);
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}
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}
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/* ===========================================================================
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* Run a set of bytes through the crc shift register. If s is a NULL
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* pointer, then initialize the crc shift register contents instead.
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* Return the current crc in either case.
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*/
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static ulg updcrc(uch * s, unsigned n)
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{
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static ulg crc = (ulg) 0xffffffffL; /* shift register contents */
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register ulg c; /* temporary variable */
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static unsigned long crc_32_tab[256];
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if (crc_32_tab[1] == 0x00000000L) {
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unsigned long csr; /* crc shift register */
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const unsigned long e = 0xedb88320L; /* polynomial exclusive-or pattern */
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int i; /* counter for all possible eight bit values */
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int k; /* byte being shifted into crc apparatus */
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/* Compute table of CRC's. */
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for (i = 1; i < 256; i++) {
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csr = i;
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/* The idea to initialize the register with the byte instead of
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* zero was stolen from Haruhiko Okumura's ar002
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*/
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for (k = 8; k; k--)
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csr = csr & 1 ? (csr >> 1) ^ e : csr >> 1;
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crc_32_tab[i] = csr;
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}
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}
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if (s == NULL) {
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c = 0xffffffffL;
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} else {
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c = crc;
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if (n)
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do {
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c = crc_32_tab[((int) c ^ (*s++)) & 0xff] ^ (c >> 8);
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} while (--n);
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}
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crc = c;
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return c ^ 0xffffffffL; /* (instead of ~c for 64-bit machines) */
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}
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/* bits.c -- output variable-length bit strings
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* Copyright (C) 1992-1993 Jean-loup Gailly
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* This is free software; you can redistribute it and/or modify it under the
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* terms of the GNU General Public License, see the file COPYING.
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*/
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/*
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* PURPOSE
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*
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* Output variable-length bit strings. Compression can be done
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* to a file or to memory. (The latter is not supported in this version.)
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*
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* DISCUSSION
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*
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* The PKZIP "deflate" file format interprets compressed file data
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* as a sequence of bits. Multi-bit strings in the file may cross
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* byte boundaries without restriction.
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*
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* The first bit of each byte is the low-order bit.
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*
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* The routines in this file allow a variable-length bit value to
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* be output right-to-left (useful for literal values). For
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* left-to-right output (useful for code strings from the tree routines),
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* the bits must have been reversed first with bi_reverse().
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*
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* For in-memory compression, the compressed bit stream goes directly
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* into the requested output buffer. The input data is read in blocks
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* by the mem_read() function. The buffer is limited to 64K on 16 bit
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* machines.
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*
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* INTERFACE
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*
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* void bi_init (FILE *zipfile)
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* Initialize the bit string routines.
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*
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* void send_bits (int value, int length)
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* Write out a bit string, taking the source bits right to
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* left.
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*
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* int bi_reverse (int value, int length)
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* Reverse the bits of a bit string, taking the source bits left to
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* right and emitting them right to left.
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*
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* void bi_windup (void)
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* Write out any remaining bits in an incomplete byte.
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*
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* void copy_block(char *buf, unsigned len, int header)
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* Copy a stored block to the zip file, storing first the length and
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* its one's complement if requested.
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*
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*/
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/* ===========================================================================
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* Local data used by the "bit string" routines.
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*/
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static file_t zfile; /* output gzip file */
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static unsigned short bi_buf;
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/* Output buffer. bits are inserted starting at the bottom (least significant
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* bits).
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*/
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#define Buf_size (8 * 2*sizeof(char))
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/* Number of bits used within bi_buf. (bi_buf might be implemented on
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* more than 16 bits on some systems.)
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*/
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static int bi_valid;
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/* Current input function. Set to mem_read for in-memory compression */
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#ifdef DEBUG
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ulg bits_sent; /* bit length of the compressed data */
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#endif
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/* ===========================================================================
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* Initialize the bit string routines.
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*/
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static void bi_init(file_t zipfile)
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{
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zfile = zipfile;
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bi_buf = 0;
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bi_valid = 0;
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#ifdef DEBUG
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bits_sent = 0L;
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#endif
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/* Set the defaults for file compression. They are set by memcompress
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* for in-memory compression.
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*/
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if (zfile != NO_FILE) {
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read_buf = file_read;
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}
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}
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/* ===========================================================================
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* Send a value on a given number of bits.
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* IN assertion: length <= 16 and value fits in length bits.
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*/
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static void send_bits(int value, int length)
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{
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#ifdef DEBUG
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Tracev((stderr, " l %2d v %4x ", length, value));
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Assert(length > 0 && length <= 15, "invalid length");
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bits_sent += (ulg) length;
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#endif
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/* If not enough room in bi_buf, use (valid) bits from bi_buf and
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* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
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* unused bits in value.
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*/
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if (bi_valid > (int) Buf_size - length) {
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bi_buf |= (value << bi_valid);
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put_short(bi_buf);
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bi_buf = (ush) value >> (Buf_size - bi_valid);
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|
bi_valid += length - Buf_size;
|
|
} else {
|
|
bi_buf |= value << bi_valid;
|
|
bi_valid += length;
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Reverse the first len bits of a code, using straightforward code (a faster
|
|
* method would use a table)
|
|
* IN assertion: 1 <= len <= 15
|
|
*/
|
|
static unsigned bi_reverse(unsigned code, int len)
|
|
{
|
|
register unsigned res = 0;
|
|
|
|
do {
|
|
res |= code & 1;
|
|
code >>= 1, res <<= 1;
|
|
} while (--len > 0);
|
|
return res >> 1;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Write out any remaining bits in an incomplete byte.
|
|
*/
|
|
static void bi_windup()
|
|
{
|
|
if (bi_valid > 8) {
|
|
put_short(bi_buf);
|
|
} else if (bi_valid > 0) {
|
|
put_byte(bi_buf);
|
|
}
|
|
bi_buf = 0;
|
|
bi_valid = 0;
|
|
#ifdef DEBUG
|
|
bits_sent = (bits_sent + 7) & ~7;
|
|
#endif
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Copy a stored block to the zip file, storing first the length and its
|
|
* one's complement if requested.
|
|
*/
|
|
static void copy_block(char *buf, unsigned len, int header)
|
|
{
|
|
bi_windup(); /* align on byte boundary */
|
|
|
|
if (header) {
|
|
put_short((ush) len);
|
|
put_short((ush) ~ len);
|
|
#ifdef DEBUG
|
|
bits_sent += 2 * 16;
|
|
#endif
|
|
}
|
|
#ifdef DEBUG
|
|
bits_sent += (ulg) len << 3;
|
|
#endif
|
|
while (len--) {
|
|
put_byte(*buf++);
|
|
}
|
|
}
|
|
|
|
/* deflate.c -- compress data using the deflation algorithm
|
|
* Copyright (C) 1992-1993 Jean-loup Gailly
|
|
* This is free software; you can redistribute it and/or modify it under the
|
|
* terms of the GNU General Public License, see the file COPYING.
|
|
*/
|
|
|
|
/*
|
|
* PURPOSE
|
|
*
|
|
* Identify new text as repetitions of old text within a fixed-
|
|
* length sliding window trailing behind the new text.
|
|
*
|
|
* DISCUSSION
|
|
*
|
|
* The "deflation" process depends on being able to identify portions
|
|
* of the input text which are identical to earlier input (within a
|
|
* sliding window trailing behind the input currently being processed).
|
|
*
|
|
* The most straightforward technique turns out to be the fastest for
|
|
* most input files: try all possible matches and select the longest.
|
|
* The key feature of this algorithm is that insertions into the string
|
|
* dictionary are very simple and thus fast, and deletions are avoided
|
|
* completely. Insertions are performed at each input character, whereas
|
|
* string matches are performed only when the previous match ends. So it
|
|
* is preferable to spend more time in matches to allow very fast string
|
|
* insertions and avoid deletions. The matching algorithm for small
|
|
* strings is inspired from that of Rabin & Karp. A brute force approach
|
|
* is used to find longer strings when a small match has been found.
|
|
* A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
|
|
* (by Leonid Broukhis).
|
|
* A previous version of this file used a more sophisticated algorithm
|
|
* (by Fiala and Greene) which is guaranteed to run in linear amortized
|
|
* time, but has a larger average cost, uses more memory and is patented.
|
|
* However the F&G algorithm may be faster for some highly redundant
|
|
* files if the parameter max_chain_length (described below) is too large.
|
|
*
|
|
* ACKNOWLEDGMENTS
|
|
*
|
|
* The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
|
|
* I found it in 'freeze' written by Leonid Broukhis.
|
|
* Thanks to many info-zippers for bug reports and testing.
|
|
*
|
|
* REFERENCES
|
|
*
|
|
* APPNOTE.TXT documentation file in PKZIP 1.93a distribution.
|
|
*
|
|
* A description of the Rabin and Karp algorithm is given in the book
|
|
* "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
|
|
*
|
|
* Fiala,E.R., and Greene,D.H.
|
|
* Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
|
|
*
|
|
* INTERFACE
|
|
*
|
|
* void lm_init (int pack_level, ush *flags)
|
|
* Initialize the "longest match" routines for a new file
|
|
*
|
|
* ulg deflate (void)
|
|
* Processes a new input file and return its compressed length. Sets
|
|
* the compressed length, crc, deflate flags and internal file
|
|
* attributes.
|
|
*/
|
|
|
|
|
|
/* ===========================================================================
|
|
* Configuration parameters
|
|
*/
|
|
|
|
/* Compile with MEDIUM_MEM to reduce the memory requirements or
|
|
* with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
|
|
* entire input file can be held in memory (not possible on 16 bit systems).
|
|
* Warning: defining these symbols affects HASH_BITS (see below) and thus
|
|
* affects the compression ratio. The compressed output
|
|
* is still correct, and might even be smaller in some cases.
|
|
*/
|
|
|
|
#ifdef SMALL_MEM
|
|
# define HASH_BITS 13 /* Number of bits used to hash strings */
|
|
#endif
|
|
#ifdef MEDIUM_MEM
|
|
# define HASH_BITS 14
|
|
#endif
|
|
#ifndef HASH_BITS
|
|
# define HASH_BITS 15
|
|
/* For portability to 16 bit machines, do not use values above 15. */
|
|
#endif
|
|
|
|
/* To save space (see unlzw.c), we overlay prev+head with tab_prefix and
|
|
* window with tab_suffix. Check that we can do this:
|
|
*/
|
|
#if (WSIZE<<1) > (1<<BITS)
|
|
# error cannot overlay window with tab_suffix and prev with tab_prefix0
|
|
#endif
|
|
#if HASH_BITS > BITS-1
|
|
# error cannot overlay head with tab_prefix1
|
|
#endif
|
|
#define HASH_SIZE (unsigned)(1<<HASH_BITS)
|
|
#define HASH_MASK (HASH_SIZE-1)
|
|
#define WMASK (WSIZE-1)
|
|
/* HASH_SIZE and WSIZE must be powers of two */
|
|
#define NIL 0
|
|
/* Tail of hash chains */
|
|
#define FAST 4
|
|
#define SLOW 2
|
|
/* speed options for the general purpose bit flag */
|
|
#ifndef TOO_FAR
|
|
# define TOO_FAR 4096
|
|
#endif
|
|
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
|
|
/* ===========================================================================
|
|
* Local data used by the "longest match" routines.
|
|
*/
|
|
typedef ush Pos;
|
|
typedef unsigned IPos;
|
|
|
|
/* A Pos is an index in the character window. We use short instead of int to
|
|
* save space in the various tables. IPos is used only for parameter passing.
|
|
*/
|
|
|
|
/* DECLARE(uch, window, 2L*WSIZE); */
|
|
/* Sliding window. Input bytes are read into the second half of the window,
|
|
* and move to the first half later to keep a dictionary of at least WSIZE
|
|
* bytes. With this organization, matches are limited to a distance of
|
|
* WSIZE-MAX_MATCH bytes, but this ensures that IO is always
|
|
* performed with a length multiple of the block size. Also, it limits
|
|
* the window size to 64K, which is quite useful on MSDOS.
|
|
* To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
|
|
* be less efficient).
|
|
*/
|
|
|
|
/* DECLARE(Pos, prev, WSIZE); */
|
|
/* Link to older string with same hash index. To limit the size of this
|
|
* array to 64K, this link is maintained only for the last 32K strings.
|
|
* An index in this array is thus a window index modulo 32K.
|
|
*/
|
|
|
|
/* DECLARE(Pos, head, 1<<HASH_BITS); */
|
|
/* Heads of the hash chains or NIL. */
|
|
|
|
static const ulg window_size = (ulg) 2 * WSIZE;
|
|
|
|
/* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
|
|
* input file length plus MIN_LOOKAHEAD.
|
|
*/
|
|
|
|
static long block_start;
|
|
|
|
/* window position at the beginning of the current output block. Gets
|
|
* negative when the window is moved backwards.
|
|
*/
|
|
|
|
static unsigned ins_h; /* hash index of string to be inserted */
|
|
|
|
#define H_SHIFT ((HASH_BITS+MIN_MATCH-1)/MIN_MATCH)
|
|
/* Number of bits by which ins_h and del_h must be shifted at each
|
|
* input step. It must be such that after MIN_MATCH steps, the oldest
|
|
* byte no longer takes part in the hash key, that is:
|
|
* H_SHIFT * MIN_MATCH >= HASH_BITS
|
|
*/
|
|
|
|
static unsigned int prev_length;
|
|
|
|
/* Length of the best match at previous step. Matches not greater than this
|
|
* are discarded. This is used in the lazy match evaluation.
|
|
*/
|
|
|
|
static unsigned strstart; /* start of string to insert */
|
|
static unsigned match_start; /* start of matching string */
|
|
static int eofile; /* flag set at end of input file */
|
|
static unsigned lookahead; /* number of valid bytes ahead in window */
|
|
|
|
static const unsigned max_chain_length = 4096;
|
|
|
|
/* To speed up deflation, hash chains are never searched beyond this length.
|
|
* A higher limit improves compression ratio but degrades the speed.
|
|
*/
|
|
|
|
static const unsigned int max_lazy_match = 258;
|
|
|
|
/* Attempt to find a better match only when the current match is strictly
|
|
* smaller than this value. This mechanism is used only for compression
|
|
* levels >= 4.
|
|
*/
|
|
#define max_insert_length max_lazy_match
|
|
/* Insert new strings in the hash table only if the match length
|
|
* is not greater than this length. This saves time but degrades compression.
|
|
* max_insert_length is used only for compression levels <= 3.
|
|
*/
|
|
|
|
static const unsigned good_match = 32;
|
|
|
|
/* Use a faster search when the previous match is longer than this */
|
|
|
|
|
|
/* Values for max_lazy_match, good_match and max_chain_length, depending on
|
|
* the desired pack level (0..9). The values given below have been tuned to
|
|
* exclude worst case performance for pathological files. Better values may be
|
|
* found for specific files.
|
|
*/
|
|
|
|
static const int nice_match = 258; /* Stop searching when current match exceeds this */
|
|
|
|
/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
|
|
* For deflate_fast() (levels <= 3) good is ignored and lazy has a different
|
|
* meaning.
|
|
*/
|
|
|
|
#define EQUAL 0
|
|
/* result of memcmp for equal strings */
|
|
|
|
/* ===========================================================================
|
|
* Prototypes for local functions.
|
|
*/
|
|
static void fill_window(void);
|
|
|
|
static int longest_match(IPos cur_match);
|
|
|
|
#ifdef DEBUG
|
|
static void check_match(IPos start, IPos match, int length);
|
|
#endif
|
|
|
|
/* ===========================================================================
|
|
* Update a hash value with the given input byte
|
|
* IN assertion: all calls to to UPDATE_HASH are made with consecutive
|
|
* input characters, so that a running hash key can be computed from the
|
|
* previous key instead of complete recalculation each time.
|
|
*/
|
|
#define UPDATE_HASH(h,c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
|
|
|
|
/* ===========================================================================
|
|
* Insert string s in the dictionary and set match_head to the previous head
|
|
* of the hash chain (the most recent string with same hash key). Return
|
|
* the previous length of the hash chain.
|
|
* IN assertion: all calls to to INSERT_STRING are made with consecutive
|
|
* input characters and the first MIN_MATCH bytes of s are valid
|
|
* (except for the last MIN_MATCH-1 bytes of the input file).
|
|
*/
|
|
#define INSERT_STRING(s, match_head) \
|
|
(UPDATE_HASH(ins_h, window[(s) + MIN_MATCH-1]), \
|
|
prev[(s) & WMASK] = match_head = head[ins_h], \
|
|
head[ins_h] = (s))
|
|
|
|
/* ===========================================================================
|
|
* Initialize the "longest match" routines for a new file
|
|
*/
|
|
static void lm_init(ush * flags)
|
|
{
|
|
register unsigned j;
|
|
|
|
/* Initialize the hash table. */
|
|
memset(head, 0, HASH_SIZE * sizeof(*head));
|
|
/* prev will be initialized on the fly */
|
|
|
|
*flags |= SLOW;
|
|
/* ??? reduce max_chain_length for binary files */
|
|
|
|
strstart = 0;
|
|
block_start = 0L;
|
|
|
|
lookahead = read_buf((char *) window,
|
|
sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
|
|
|
|
if (lookahead == 0 || lookahead == (unsigned) EOF) {
|
|
eofile = 1, lookahead = 0;
|
|
return;
|
|
}
|
|
eofile = 0;
|
|
/* Make sure that we always have enough lookahead. This is important
|
|
* if input comes from a device such as a tty.
|
|
*/
|
|
while (lookahead < MIN_LOOKAHEAD && !eofile)
|
|
fill_window();
|
|
|
|
ins_h = 0;
|
|
for (j = 0; j < MIN_MATCH - 1; j++)
|
|
UPDATE_HASH(ins_h, window[j]);
|
|
/* If lookahead < MIN_MATCH, ins_h is garbage, but this is
|
|
* not important since only literal bytes will be emitted.
|
|
*/
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Set match_start to the longest match starting at the given string and
|
|
* return its length. Matches shorter or equal to prev_length are discarded,
|
|
* in which case the result is equal to prev_length and match_start is
|
|
* garbage.
|
|
* IN assertions: cur_match is the head of the hash chain for the current
|
|
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
|
|
*/
|
|
|
|
/* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
|
|
* match.s. The code is functionally equivalent, so you can use the C version
|
|
* if desired.
|
|
*/
|
|
static int longest_match(IPos cur_match)
|
|
{
|
|
unsigned chain_length = max_chain_length; /* max hash chain length */
|
|
register uch *scan = window + strstart; /* current string */
|
|
register uch *match; /* matched string */
|
|
register int len; /* length of current match */
|
|
int best_len = prev_length; /* best match length so far */
|
|
IPos limit =
|
|
strstart > (IPos) MAX_DIST ? strstart - (IPos) MAX_DIST : NIL;
|
|
/* Stop when cur_match becomes <= limit. To simplify the code,
|
|
* we prevent matches with the string of window index 0.
|
|
*/
|
|
|
|
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
|
|
* It is easy to get rid of this optimization if necessary.
|
|
*/
|
|
#if HASH_BITS < 8 || MAX_MATCH != 258
|
|
# error Code too clever
|
|
#endif
|
|
register uch *strend = window + strstart + MAX_MATCH;
|
|
register uch scan_end1 = scan[best_len - 1];
|
|
register uch scan_end = scan[best_len];
|
|
|
|
/* Do not waste too much time if we already have a good match: */
|
|
if (prev_length >= good_match) {
|
|
chain_length >>= 2;
|
|
}
|
|
Assert(strstart <= window_size - MIN_LOOKAHEAD, "insufficient lookahead");
|
|
|
|
do {
|
|
Assert(cur_match < strstart, "no future");
|
|
match = window + cur_match;
|
|
|
|
/* Skip to next match if the match length cannot increase
|
|
* or if the match length is less than 2:
|
|
*/
|
|
if (match[best_len] != scan_end ||
|
|
match[best_len - 1] != scan_end1 ||
|
|
*match != *scan || *++match != scan[1])
|
|
continue;
|
|
|
|
/* The check at best_len-1 can be removed because it will be made
|
|
* again later. (This heuristic is not always a win.)
|
|
* It is not necessary to compare scan[2] and match[2] since they
|
|
* are always equal when the other bytes match, given that
|
|
* the hash keys are equal and that HASH_BITS >= 8.
|
|
*/
|
|
scan += 2, match++;
|
|
|
|
/* We check for insufficient lookahead only every 8th comparison;
|
|
* the 256th check will be made at strstart+258.
|
|
*/
|
|
do {
|
|
} while (*++scan == *++match && *++scan == *++match &&
|
|
*++scan == *++match && *++scan == *++match &&
|
|
*++scan == *++match && *++scan == *++match &&
|
|
*++scan == *++match && *++scan == *++match && scan < strend);
|
|
|
|
len = MAX_MATCH - (int) (strend - scan);
|
|
scan = strend - MAX_MATCH;
|
|
|
|
if (len > best_len) {
|
|
match_start = cur_match;
|
|
best_len = len;
|
|
if (len >= nice_match)
|
|
break;
|
|
scan_end1 = scan[best_len - 1];
|
|
scan_end = scan[best_len];
|
|
}
|
|
} while ((cur_match = prev[cur_match & WMASK]) > limit
|
|
&& --chain_length != 0);
|
|
|
|
return best_len;
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
/* ===========================================================================
|
|
* Check that the match at match_start is indeed a match.
|
|
*/
|
|
static void check_match(IPos start, IPos match, int length)
|
|
{
|
|
/* check that the match is indeed a match */
|
|
if (memcmp((char *) window + match,
|
|
(char *) window + start, length) != EQUAL) {
|
|
bb_error_msg(" start %d, match %d, length %d", start, match, length);
|
|
bb_error_msg("invalid match");
|
|
}
|
|
if (verbose > 1) {
|
|
bb_error_msg("\\[%d,%d]", start - match, length);
|
|
do {
|
|
putc(window[start++], stderr);
|
|
} while (--length != 0);
|
|
}
|
|
}
|
|
#else
|
|
# define check_match(start, match, length)
|
|
#endif
|
|
|
|
/* ===========================================================================
|
|
* Fill the window when the lookahead becomes insufficient.
|
|
* Updates strstart and lookahead, and sets eofile if end of input file.
|
|
* IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
|
|
* OUT assertions: at least one byte has been read, or eofile is set;
|
|
* file reads are performed for at least two bytes (required for the
|
|
* translate_eol option).
|
|
*/
|
|
static void fill_window()
|
|
{
|
|
register unsigned n, m;
|
|
unsigned more =
|
|
(unsigned) (window_size - (ulg) lookahead - (ulg) strstart);
|
|
/* Amount of free space at the end of the window. */
|
|
|
|
/* If the window is almost full and there is insufficient lookahead,
|
|
* move the upper half to the lower one to make room in the upper half.
|
|
*/
|
|
if (more == (unsigned) EOF) {
|
|
/* Very unlikely, but possible on 16 bit machine if strstart == 0
|
|
* and lookahead == 1 (input done one byte at time)
|
|
*/
|
|
more--;
|
|
} else if (strstart >= WSIZE + MAX_DIST) {
|
|
/* By the IN assertion, the window is not empty so we can't confuse
|
|
* more == 0 with more == 64K on a 16 bit machine.
|
|
*/
|
|
Assert(window_size == (ulg) 2 * WSIZE, "no sliding with BIG_MEM");
|
|
|
|
memcpy((char *) window, (char *) window + WSIZE, (unsigned) WSIZE);
|
|
match_start -= WSIZE;
|
|
strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
|
|
|
|
block_start -= (long) WSIZE;
|
|
|
|
for (n = 0; n < HASH_SIZE; n++) {
|
|
m = head[n];
|
|
head[n] = (Pos) (m >= WSIZE ? m - WSIZE : NIL);
|
|
}
|
|
for (n = 0; n < WSIZE; n++) {
|
|
m = prev[n];
|
|
prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : NIL);
|
|
/* If n is not on any hash chain, prev[n] is garbage but
|
|
* its value will never be used.
|
|
*/
|
|
}
|
|
more += WSIZE;
|
|
}
|
|
/* At this point, more >= 2 */
|
|
if (!eofile) {
|
|
n = read_buf((char *) window + strstart + lookahead, more);
|
|
if (n == 0 || n == (unsigned) EOF) {
|
|
eofile = 1;
|
|
} else {
|
|
lookahead += n;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Flush the current block, with given end-of-file flag.
|
|
* IN assertion: strstart is set to the end of the current match.
|
|
*/
|
|
#define FLUSH_BLOCK(eof) \
|
|
flush_block(block_start >= 0L ? (char*)&window[(unsigned)block_start] : \
|
|
(char*)NULL, (long)strstart - block_start, (eof))
|
|
|
|
/* ===========================================================================
|
|
* Same as above, but achieves better compression. We use a lazy
|
|
* evaluation for matches: a match is finally adopted only if there is
|
|
* no better match at the next window position.
|
|
*/
|
|
static ulg deflate()
|
|
{
|
|
IPos hash_head; /* head of hash chain */
|
|
IPos prev_match; /* previous match */
|
|
int flush; /* set if current block must be flushed */
|
|
int match_available = 0; /* set if previous match exists */
|
|
register unsigned match_length = MIN_MATCH - 1; /* length of best match */
|
|
|
|
/* Process the input block. */
|
|
while (lookahead != 0) {
|
|
/* Insert the string window[strstart .. strstart+2] in the
|
|
* dictionary, and set hash_head to the head of the hash chain:
|
|
*/
|
|
INSERT_STRING(strstart, hash_head);
|
|
|
|
/* Find the longest match, discarding those <= prev_length.
|
|
*/
|
|
prev_length = match_length, prev_match = match_start;
|
|
match_length = MIN_MATCH - 1;
|
|
|
|
if (hash_head != NIL && prev_length < max_lazy_match &&
|
|
strstart - hash_head <= MAX_DIST) {
|
|
/* To simplify the code, we prevent matches with the string
|
|
* of window index 0 (in particular we have to avoid a match
|
|
* of the string with itself at the start of the input file).
|
|
*/
|
|
match_length = longest_match(hash_head);
|
|
/* longest_match() sets match_start */
|
|
if (match_length > lookahead)
|
|
match_length = lookahead;
|
|
|
|
/* Ignore a length 3 match if it is too distant: */
|
|
if (match_length == MIN_MATCH && strstart - match_start > TOO_FAR) {
|
|
/* If prev_match is also MIN_MATCH, match_start is garbage
|
|
* but we will ignore the current match anyway.
|
|
*/
|
|
match_length--;
|
|
}
|
|
}
|
|
/* If there was a match at the previous step and the current
|
|
* match is not better, output the previous match:
|
|
*/
|
|
if (prev_length >= MIN_MATCH && match_length <= prev_length) {
|
|
|
|
check_match(strstart - 1, prev_match, prev_length);
|
|
|
|
flush =
|
|
ct_tally(strstart - 1 - prev_match, prev_length - MIN_MATCH);
|
|
|
|
/* Insert in hash table all strings up to the end of the match.
|
|
* strstart-1 and strstart are already inserted.
|
|
*/
|
|
lookahead -= prev_length - 1;
|
|
prev_length -= 2;
|
|
do {
|
|
strstart++;
|
|
INSERT_STRING(strstart, hash_head);
|
|
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
|
|
* always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
|
|
* these bytes are garbage, but it does not matter since the
|
|
* next lookahead bytes will always be emitted as literals.
|
|
*/
|
|
} while (--prev_length != 0);
|
|
match_available = 0;
|
|
match_length = MIN_MATCH - 1;
|
|
strstart++;
|
|
if (flush)
|
|
FLUSH_BLOCK(0), block_start = strstart;
|
|
|
|
} else if (match_available) {
|
|
/* If there was no match at the previous position, output a
|
|
* single literal. If there was a match but the current match
|
|
* is longer, truncate the previous match to a single literal.
|
|
*/
|
|
Tracevv((stderr, "%c", window[strstart - 1]));
|
|
if (ct_tally(0, window[strstart - 1])) {
|
|
FLUSH_BLOCK(0), block_start = strstart;
|
|
}
|
|
strstart++;
|
|
lookahead--;
|
|
} else {
|
|
/* There is no previous match to compare with, wait for
|
|
* the next step to decide.
|
|
*/
|
|
match_available = 1;
|
|
strstart++;
|
|
lookahead--;
|
|
}
|
|
Assert(strstart <= isize && lookahead <= isize, "a bit too far");
|
|
|
|
/* Make sure that we always have enough lookahead, except
|
|
* at the end of the input file. We need MAX_MATCH bytes
|
|
* for the next match, plus MIN_MATCH bytes to insert the
|
|
* string following the next match.
|
|
*/
|
|
while (lookahead < MIN_LOOKAHEAD && !eofile)
|
|
fill_window();
|
|
}
|
|
if (match_available)
|
|
ct_tally(0, window[strstart - 1]);
|
|
|
|
return FLUSH_BLOCK(1); /* eof */
|
|
}
|
|
|
|
/* gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
|
|
* Copyright (C) 1992-1993 Jean-loup Gailly
|
|
* The unzip code was written and put in the public domain by Mark Adler.
|
|
* Portions of the lzw code are derived from the public domain 'compress'
|
|
* written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
|
|
* Ken Turkowski, Dave Mack and Peter Jannesen.
|
|
*
|
|
* See the license_msg below and the file COPYING for the software license.
|
|
* See the file algorithm.doc for the compression algorithms and file formats.
|
|
*/
|
|
|
|
/* Compress files with zip algorithm and 'compress' interface.
|
|
* See usage() and help() functions below for all options.
|
|
* Outputs:
|
|
* file.gz: compressed file with same mode, owner, and utimes
|
|
* or stdout with -c option or if stdin used as input.
|
|
* If the output file name had to be truncated, the original name is kept
|
|
* in the compressed file.
|
|
*/
|
|
|
|
/* configuration */
|
|
|
|
typedef struct dirent dir_type;
|
|
|
|
/* ======================================================================== */
|
|
int gzip_main(int argc, char **argv)
|
|
{
|
|
int result;
|
|
int inFileNum;
|
|
int outFileNum;
|
|
struct stat statBuf;
|
|
char *delFileName;
|
|
int tostdout = 0;
|
|
int force = 0;
|
|
int opt;
|
|
|
|
while ((opt = getopt(argc, argv, "cf123456789dq")) != -1) {
|
|
switch (opt) {
|
|
case 'c':
|
|
tostdout = 1;
|
|
break;
|
|
case 'f':
|
|
force = 1;
|
|
break;
|
|
/* Ignore 1-9 (compression level) options */
|
|
case '1':
|
|
case '2':
|
|
case '3':
|
|
case '4':
|
|
case '5':
|
|
case '6':
|
|
case '7':
|
|
case '8':
|
|
case '9':
|
|
break;
|
|
case 'q':
|
|
break;
|
|
#ifdef CONFIG_GUNZIP
|
|
case 'd':
|
|
optind = 1;
|
|
return gunzip_main(argc, argv);
|
|
#endif
|
|
default:
|
|
bb_show_usage();
|
|
}
|
|
}
|
|
|
|
foreground = signal(SIGINT, SIG_IGN) != SIG_IGN;
|
|
if (foreground) {
|
|
(void) signal(SIGINT, abort_gzip);
|
|
}
|
|
#ifdef SIGTERM
|
|
if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
|
|
(void) signal(SIGTERM, abort_gzip);
|
|
}
|
|
#endif
|
|
#ifdef SIGHUP
|
|
if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
|
|
(void) signal(SIGHUP, abort_gzip);
|
|
}
|
|
#endif
|
|
|
|
strncpy(z_suffix, Z_SUFFIX, sizeof(z_suffix) - 1);
|
|
z_len = strlen(z_suffix);
|
|
|
|
/* Allocate all global buffers (for DYN_ALLOC option) */
|
|
ALLOC(uch, inbuf, INBUFSIZ + INBUF_EXTRA);
|
|
ALLOC(uch, outbuf, OUTBUFSIZ + OUTBUF_EXTRA);
|
|
ALLOC(ush, d_buf, DIST_BUFSIZE);
|
|
ALLOC(uch, window, 2L * WSIZE);
|
|
ALLOC(ush, tab_prefix, 1L << BITS);
|
|
|
|
clear_bufs();
|
|
part_nb = 0;
|
|
|
|
if (optind == argc) {
|
|
time_stamp = 0;
|
|
ifile_size = -1L;
|
|
zip(STDIN_FILENO, STDOUT_FILENO);
|
|
} else {
|
|
int i;
|
|
|
|
for (i = optind; i < argc; i++) {
|
|
char *path = NULL;
|
|
|
|
clear_bufs();
|
|
if (strcmp(argv[i], "-") == 0) {
|
|
time_stamp = 0;
|
|
ifile_size = -1L;
|
|
inFileNum = STDIN_FILENO;
|
|
outFileNum = STDOUT_FILENO;
|
|
} else {
|
|
inFileNum = open(argv[i], O_RDONLY);
|
|
if (inFileNum < 0 || fstat(inFileNum, &statBuf) < 0)
|
|
bb_perror_msg_and_die("%s", argv[i]);
|
|
time_stamp = statBuf.st_ctime;
|
|
ifile_size = statBuf.st_size;
|
|
|
|
if (!tostdout) {
|
|
path = xmalloc(strlen(argv[i]) + 4);
|
|
strcpy(path, argv[i]);
|
|
strcat(path, ".gz");
|
|
|
|
/* Open output file */
|
|
#if (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 1)
|
|
outFileNum =
|
|
open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW);
|
|
#else
|
|
outFileNum = open(path, O_RDWR | O_CREAT | O_EXCL);
|
|
#endif
|
|
if (outFileNum < 0) {
|
|
bb_perror_msg("%s", path);
|
|
free(path);
|
|
continue;
|
|
}
|
|
|
|
/* Set permissions on the file */
|
|
fchmod(outFileNum, statBuf.st_mode);
|
|
} else
|
|
outFileNum = STDOUT_FILENO;
|
|
}
|
|
|
|
if (path == NULL && isatty(outFileNum) && force == 0) {
|
|
bb_error_msg
|
|
("compressed data not written to a terminal. Use -f to force compression.");
|
|
free(path);
|
|
continue;
|
|
}
|
|
|
|
result = zip(inFileNum, outFileNum);
|
|
|
|
if (path != NULL) {
|
|
close(inFileNum);
|
|
close(outFileNum);
|
|
|
|
/* Delete the original file */
|
|
if (result == OK)
|
|
delFileName = argv[i];
|
|
else
|
|
delFileName = path;
|
|
|
|
if (unlink(delFileName) < 0)
|
|
bb_perror_msg("%s", delFileName);
|
|
}
|
|
|
|
free(path);
|
|
}
|
|
}
|
|
|
|
return (exit_code);
|
|
}
|
|
|
|
/* trees.c -- output deflated data using Huffman coding
|
|
* Copyright (C) 1992-1993 Jean-loup Gailly
|
|
* This is free software; you can redistribute it and/or modify it under the
|
|
* terms of the GNU General Public License, see the file COPYING.
|
|
*/
|
|
|
|
/*
|
|
* PURPOSE
|
|
*
|
|
* Encode various sets of source values using variable-length
|
|
* binary code trees.
|
|
*
|
|
* DISCUSSION
|
|
*
|
|
* The PKZIP "deflation" process uses several Huffman trees. The more
|
|
* common source values are represented by shorter bit sequences.
|
|
*
|
|
* Each code tree is stored in the ZIP file in a compressed form
|
|
* which is itself a Huffman encoding of the lengths of
|
|
* all the code strings (in ascending order by source values).
|
|
* The actual code strings are reconstructed from the lengths in
|
|
* the UNZIP process, as described in the "application note"
|
|
* (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
|
|
*
|
|
* REFERENCES
|
|
*
|
|
* Lynch, Thomas J.
|
|
* Data Compression: Techniques and Applications, pp. 53-55.
|
|
* Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
|
|
*
|
|
* Storer, James A.
|
|
* Data Compression: Methods and Theory, pp. 49-50.
|
|
* Computer Science Press, 1988. ISBN 0-7167-8156-5.
|
|
*
|
|
* Sedgewick, R.
|
|
* Algorithms, p290.
|
|
* Addison-Wesley, 1983. ISBN 0-201-06672-6.
|
|
*
|
|
* INTERFACE
|
|
*
|
|
* void ct_init (ush *attr, int *methodp)
|
|
* Allocate the match buffer, initialize the various tables and save
|
|
* the location of the internal file attribute (ascii/binary) and
|
|
* method (DEFLATE/STORE)
|
|
*
|
|
* void ct_tally (int dist, int lc);
|
|
* Save the match info and tally the frequency counts.
|
|
*
|
|
* long flush_block (char *buf, ulg stored_len, int eof)
|
|
* Determine the best encoding for the current block: dynamic trees,
|
|
* static trees or store, and output the encoded block to the zip
|
|
* file. Returns the total compressed length for the file so far.
|
|
*
|
|
*/
|
|
|
|
/* ===========================================================================
|
|
* Constants
|
|
*/
|
|
|
|
#define MAX_BITS 15
|
|
/* All codes must not exceed MAX_BITS bits */
|
|
|
|
#define MAX_BL_BITS 7
|
|
/* Bit length codes must not exceed MAX_BL_BITS bits */
|
|
|
|
#define LENGTH_CODES 29
|
|
/* number of length codes, not counting the special END_BLOCK code */
|
|
|
|
#define LITERALS 256
|
|
/* number of literal bytes 0..255 */
|
|
|
|
#define END_BLOCK 256
|
|
/* end of block literal code */
|
|
|
|
#define L_CODES (LITERALS+1+LENGTH_CODES)
|
|
/* number of Literal or Length codes, including the END_BLOCK code */
|
|
|
|
#define D_CODES 30
|
|
/* number of distance codes */
|
|
|
|
#define BL_CODES 19
|
|
/* number of codes used to transfer the bit lengths */
|
|
|
|
typedef uch extra_bits_t;
|
|
|
|
/* extra bits for each length code */
|
|
static const extra_bits_t extra_lbits[LENGTH_CODES]
|
|
= { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
|
|
4, 4, 5, 5, 5, 5, 0
|
|
};
|
|
|
|
/* extra bits for each distance code */
|
|
static const extra_bits_t extra_dbits[D_CODES]
|
|
= { 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
|
|
10, 10, 11, 11, 12, 12, 13, 13
|
|
};
|
|
|
|
/* extra bits for each bit length code */
|
|
static const extra_bits_t extra_blbits[BL_CODES]
|
|
= { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
|
|
|
|
#define STORED_BLOCK 0
|
|
#define STATIC_TREES 1
|
|
#define DYN_TREES 2
|
|
/* The three kinds of block type */
|
|
|
|
#ifndef LIT_BUFSIZE
|
|
# ifdef SMALL_MEM
|
|
# define LIT_BUFSIZE 0x2000
|
|
# else
|
|
# ifdef MEDIUM_MEM
|
|
# define LIT_BUFSIZE 0x4000
|
|
# else
|
|
# define LIT_BUFSIZE 0x8000
|
|
# endif
|
|
# endif
|
|
#endif
|
|
#ifndef DIST_BUFSIZE
|
|
# define DIST_BUFSIZE LIT_BUFSIZE
|
|
#endif
|
|
/* Sizes of match buffers for literals/lengths and distances. There are
|
|
* 4 reasons for limiting LIT_BUFSIZE to 64K:
|
|
* - frequencies can be kept in 16 bit counters
|
|
* - if compression is not successful for the first block, all input data is
|
|
* still in the window so we can still emit a stored block even when input
|
|
* comes from standard input. (This can also be done for all blocks if
|
|
* LIT_BUFSIZE is not greater than 32K.)
|
|
* - if compression is not successful for a file smaller than 64K, we can
|
|
* even emit a stored file instead of a stored block (saving 5 bytes).
|
|
* - creating new Huffman trees less frequently may not provide fast
|
|
* adaptation to changes in the input data statistics. (Take for
|
|
* example a binary file with poorly compressible code followed by
|
|
* a highly compressible string table.) Smaller buffer sizes give
|
|
* fast adaptation but have of course the overhead of transmitting trees
|
|
* more frequently.
|
|
* - I can't count above 4
|
|
* The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
|
|
* memory at the expense of compression). Some optimizations would be possible
|
|
* if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
|
|
*/
|
|
#if LIT_BUFSIZE > INBUFSIZ
|
|
#error cannot overlay l_buf and inbuf
|
|
#endif
|
|
#define REP_3_6 16
|
|
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
|
|
#define REPZ_3_10 17
|
|
/* repeat a zero length 3-10 times (3 bits of repeat count) */
|
|
#define REPZ_11_138 18
|
|
/* repeat a zero length 11-138 times (7 bits of repeat count) */
|
|
|
|
/* ===========================================================================
|
|
* Local data
|
|
*/
|
|
|
|
/* Data structure describing a single value and its code string. */
|
|
typedef struct ct_data {
|
|
union {
|
|
ush freq; /* frequency count */
|
|
ush code; /* bit string */
|
|
} fc;
|
|
union {
|
|
ush dad; /* father node in Huffman tree */
|
|
ush len; /* length of bit string */
|
|
} dl;
|
|
} ct_data;
|
|
|
|
#define Freq fc.freq
|
|
#define Code fc.code
|
|
#define Dad dl.dad
|
|
#define Len dl.len
|
|
|
|
#define HEAP_SIZE (2*L_CODES+1)
|
|
/* maximum heap size */
|
|
|
|
static ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
|
|
static ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
|
|
|
|
static ct_data static_ltree[L_CODES + 2];
|
|
|
|
/* The static literal tree. Since the bit lengths are imposed, there is no
|
|
* need for the L_CODES extra codes used during heap construction. However
|
|
* The codes 286 and 287 are needed to build a canonical tree (see ct_init
|
|
* below).
|
|
*/
|
|
|
|
static ct_data static_dtree[D_CODES];
|
|
|
|
/* The static distance tree. (Actually a trivial tree since all codes use
|
|
* 5 bits.)
|
|
*/
|
|
|
|
static ct_data bl_tree[2 * BL_CODES + 1];
|
|
|
|
/* Huffman tree for the bit lengths */
|
|
|
|
typedef struct tree_desc {
|
|
ct_data *dyn_tree; /* the dynamic tree */
|
|
ct_data *static_tree; /* corresponding static tree or NULL */
|
|
const extra_bits_t *extra_bits; /* extra bits for each code or NULL */
|
|
int extra_base; /* base index for extra_bits */
|
|
int elems; /* max number of elements in the tree */
|
|
int max_length; /* max bit length for the codes */
|
|
int max_code; /* largest code with non zero frequency */
|
|
} tree_desc;
|
|
|
|
static tree_desc l_desc =
|
|
{ dyn_ltree, static_ltree, extra_lbits, LITERALS + 1, L_CODES,
|
|
MAX_BITS, 0
|
|
};
|
|
|
|
static tree_desc d_desc =
|
|
{ dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0 };
|
|
|
|
static tree_desc bl_desc =
|
|
{ bl_tree, (ct_data *) 0, extra_blbits, 0, BL_CODES, MAX_BL_BITS,
|
|
0
|
|
};
|
|
|
|
|
|
static ush bl_count[MAX_BITS + 1];
|
|
|
|
/* number of codes at each bit length for an optimal tree */
|
|
|
|
static const uch bl_order[BL_CODES]
|
|
= { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
|
|
|
|
/* The lengths of the bit length codes are sent in order of decreasing
|
|
* probability, to avoid transmitting the lengths for unused bit length codes.
|
|
*/
|
|
|
|
static int heap[2 * L_CODES + 1]; /* heap used to build the Huffman trees */
|
|
static int heap_len; /* number of elements in the heap */
|
|
static int heap_max; /* element of largest frequency */
|
|
|
|
/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
|
|
* The same heap array is used to build all trees.
|
|
*/
|
|
|
|
static uch depth[2 * L_CODES + 1];
|
|
|
|
/* Depth of each subtree used as tie breaker for trees of equal frequency */
|
|
|
|
static uch length_code[MAX_MATCH - MIN_MATCH + 1];
|
|
|
|
/* length code for each normalized match length (0 == MIN_MATCH) */
|
|
|
|
static uch dist_code[512];
|
|
|
|
/* distance codes. The first 256 values correspond to the distances
|
|
* 3 .. 258, the last 256 values correspond to the top 8 bits of
|
|
* the 15 bit distances.
|
|
*/
|
|
|
|
static int base_length[LENGTH_CODES];
|
|
|
|
/* First normalized length for each code (0 = MIN_MATCH) */
|
|
|
|
static int base_dist[D_CODES];
|
|
|
|
/* First normalized distance for each code (0 = distance of 1) */
|
|
|
|
#define l_buf inbuf
|
|
/* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */
|
|
|
|
/* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */
|
|
|
|
static uch flag_buf[(LIT_BUFSIZE / 8)];
|
|
|
|
/* flag_buf is a bit array distinguishing literals from lengths in
|
|
* l_buf, thus indicating the presence or absence of a distance.
|
|
*/
|
|
|
|
static unsigned last_lit; /* running index in l_buf */
|
|
static unsigned last_dist; /* running index in d_buf */
|
|
static unsigned last_flags; /* running index in flag_buf */
|
|
static uch flags; /* current flags not yet saved in flag_buf */
|
|
static uch flag_bit; /* current bit used in flags */
|
|
|
|
/* bits are filled in flags starting at bit 0 (least significant).
|
|
* Note: these flags are overkill in the current code since we don't
|
|
* take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
|
|
*/
|
|
|
|
static ulg opt_len; /* bit length of current block with optimal trees */
|
|
static ulg static_len; /* bit length of current block with static trees */
|
|
|
|
static ulg compressed_len; /* total bit length of compressed file */
|
|
|
|
|
|
static ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */
|
|
static int *file_method; /* pointer to DEFLATE or STORE */
|
|
|
|
/* ===========================================================================
|
|
* Local (static) routines in this file.
|
|
*/
|
|
|
|
static void init_block(void);
|
|
static void pqdownheap(ct_data * tree, int k);
|
|
static void gen_bitlen(tree_desc * desc);
|
|
static void gen_codes(ct_data * tree, int max_code);
|
|
static void build_tree(tree_desc * desc);
|
|
static void scan_tree(ct_data * tree, int max_code);
|
|
static void send_tree(ct_data * tree, int max_code);
|
|
static int build_bl_tree(void);
|
|
static void send_all_trees(int lcodes, int dcodes, int blcodes);
|
|
static void compress_block(ct_data * ltree, ct_data * dtree);
|
|
static void set_file_type(void);
|
|
|
|
|
|
#ifndef DEBUG
|
|
# define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len)
|
|
/* Send a code of the given tree. c and tree must not have side effects */
|
|
|
|
#else /* DEBUG */
|
|
# define send_code(c, tree) \
|
|
{ if (verbose>1) bb_error_msg("\ncd %3d ",(c)); \
|
|
send_bits(tree[c].Code, tree[c].Len); }
|
|
#endif
|
|
|
|
#define d_code(dist) \
|
|
((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
|
|
/* Mapping from a distance to a distance code. dist is the distance - 1 and
|
|
* must not have side effects. dist_code[256] and dist_code[257] are never
|
|
* used.
|
|
*/
|
|
|
|
/* the arguments must not have side effects */
|
|
|
|
/* ===========================================================================
|
|
* Allocate the match buffer, initialize the various tables and save the
|
|
* location of the internal file attribute (ascii/binary) and method
|
|
* (DEFLATE/STORE).
|
|
*/
|
|
static void ct_init(ush * attr, int *methodp)
|
|
{
|
|
int n; /* iterates over tree elements */
|
|
int bits; /* bit counter */
|
|
int length; /* length value */
|
|
int code; /* code value */
|
|
int dist; /* distance index */
|
|
|
|
file_type = attr;
|
|
file_method = methodp;
|
|
compressed_len = 0L;
|
|
|
|
if (static_dtree[0].Len != 0)
|
|
return; /* ct_init already called */
|
|
|
|
/* Initialize the mapping length (0..255) -> length code (0..28) */
|
|
length = 0;
|
|
for (code = 0; code < LENGTH_CODES - 1; code++) {
|
|
base_length[code] = length;
|
|
for (n = 0; n < (1 << extra_lbits[code]); n++) {
|
|
length_code[length++] = (uch) code;
|
|
}
|
|
}
|
|
Assert(length == 256, "ct_init: length != 256");
|
|
/* Note that the length 255 (match length 258) can be represented
|
|
* in two different ways: code 284 + 5 bits or code 285, so we
|
|
* overwrite length_code[255] to use the best encoding:
|
|
*/
|
|
length_code[length - 1] = (uch) code;
|
|
|
|
/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
|
|
dist = 0;
|
|
for (code = 0; code < 16; code++) {
|
|
base_dist[code] = dist;
|
|
for (n = 0; n < (1 << extra_dbits[code]); n++) {
|
|
dist_code[dist++] = (uch) code;
|
|
}
|
|
}
|
|
Assert(dist == 256, "ct_init: dist != 256");
|
|
dist >>= 7; /* from now on, all distances are divided by 128 */
|
|
for (; code < D_CODES; code++) {
|
|
base_dist[code] = dist << 7;
|
|
for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
|
|
dist_code[256 + dist++] = (uch) code;
|
|
}
|
|
}
|
|
Assert(dist == 256, "ct_init: 256+dist != 512");
|
|
|
|
/* Construct the codes of the static literal tree */
|
|
for (bits = 0; bits <= MAX_BITS; bits++)
|
|
bl_count[bits] = 0;
|
|
n = 0;
|
|
while (n <= 143)
|
|
static_ltree[n++].Len = 8, bl_count[8]++;
|
|
while (n <= 255)
|
|
static_ltree[n++].Len = 9, bl_count[9]++;
|
|
while (n <= 279)
|
|
static_ltree[n++].Len = 7, bl_count[7]++;
|
|
while (n <= 287)
|
|
static_ltree[n++].Len = 8, bl_count[8]++;
|
|
/* Codes 286 and 287 do not exist, but we must include them in the
|
|
* tree construction to get a canonical Huffman tree (longest code
|
|
* all ones)
|
|
*/
|
|
gen_codes((ct_data *) static_ltree, L_CODES + 1);
|
|
|
|
/* The static distance tree is trivial: */
|
|
for (n = 0; n < D_CODES; n++) {
|
|
static_dtree[n].Len = 5;
|
|
static_dtree[n].Code = bi_reverse(n, 5);
|
|
}
|
|
|
|
/* Initialize the first block of the first file: */
|
|
init_block();
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Initialize a new block.
|
|
*/
|
|
static void init_block()
|
|
{
|
|
int n; /* iterates over tree elements */
|
|
|
|
/* Initialize the trees. */
|
|
for (n = 0; n < L_CODES; n++)
|
|
dyn_ltree[n].Freq = 0;
|
|
for (n = 0; n < D_CODES; n++)
|
|
dyn_dtree[n].Freq = 0;
|
|
for (n = 0; n < BL_CODES; n++)
|
|
bl_tree[n].Freq = 0;
|
|
|
|
dyn_ltree[END_BLOCK].Freq = 1;
|
|
opt_len = static_len = 0L;
|
|
last_lit = last_dist = last_flags = 0;
|
|
flags = 0;
|
|
flag_bit = 1;
|
|
}
|
|
|
|
#define SMALLEST 1
|
|
/* Index within the heap array of least frequent node in the Huffman tree */
|
|
|
|
|
|
/* ===========================================================================
|
|
* Remove the smallest element from the heap and recreate the heap with
|
|
* one less element. Updates heap and heap_len.
|
|
*/
|
|
#define pqremove(tree, top) \
|
|
{\
|
|
top = heap[SMALLEST]; \
|
|
heap[SMALLEST] = heap[heap_len--]; \
|
|
pqdownheap(tree, SMALLEST); \
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Compares to subtrees, using the tree depth as tie breaker when
|
|
* the subtrees have equal frequency. This minimizes the worst case length.
|
|
*/
|
|
#define smaller(tree, n, m) \
|
|
(tree[n].Freq < tree[m].Freq || \
|
|
(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
|
|
|
|
/* ===========================================================================
|
|
* Restore the heap property by moving down the tree starting at node k,
|
|
* exchanging a node with the smallest of its two sons if necessary, stopping
|
|
* when the heap property is re-established (each father smaller than its
|
|
* two sons).
|
|
*/
|
|
static void pqdownheap(ct_data * tree, int k)
|
|
{
|
|
int v = heap[k];
|
|
int j = k << 1; /* left son of k */
|
|
|
|
while (j <= heap_len) {
|
|
/* Set j to the smallest of the two sons: */
|
|
if (j < heap_len && smaller(tree, heap[j + 1], heap[j]))
|
|
j++;
|
|
|
|
/* Exit if v is smaller than both sons */
|
|
if (smaller(tree, v, heap[j]))
|
|
break;
|
|
|
|
/* Exchange v with the smallest son */
|
|
heap[k] = heap[j];
|
|
k = j;
|
|
|
|
/* And continue down the tree, setting j to the left son of k */
|
|
j <<= 1;
|
|
}
|
|
heap[k] = v;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Compute the optimal bit lengths for a tree and update the total bit length
|
|
* for the current block.
|
|
* IN assertion: the fields freq and dad are set, heap[heap_max] and
|
|
* above are the tree nodes sorted by increasing frequency.
|
|
* OUT assertions: the field len is set to the optimal bit length, the
|
|
* array bl_count contains the frequencies for each bit length.
|
|
* The length opt_len is updated; static_len is also updated if stree is
|
|
* not null.
|
|
*/
|
|
static void gen_bitlen(tree_desc * desc)
|
|
{
|
|
ct_data *tree = desc->dyn_tree;
|
|
const extra_bits_t *extra = desc->extra_bits;
|
|
int base = desc->extra_base;
|
|
int max_code = desc->max_code;
|
|
int max_length = desc->max_length;
|
|
ct_data *stree = desc->static_tree;
|
|
int h; /* heap index */
|
|
int n, m; /* iterate over the tree elements */
|
|
int bits; /* bit length */
|
|
int xbits; /* extra bits */
|
|
ush f; /* frequency */
|
|
int overflow = 0; /* number of elements with bit length too large */
|
|
|
|
for (bits = 0; bits <= MAX_BITS; bits++)
|
|
bl_count[bits] = 0;
|
|
|
|
/* In a first pass, compute the optimal bit lengths (which may
|
|
* overflow in the case of the bit length tree).
|
|
*/
|
|
tree[heap[heap_max]].Len = 0; /* root of the heap */
|
|
|
|
for (h = heap_max + 1; h < HEAP_SIZE; h++) {
|
|
n = heap[h];
|
|
bits = tree[tree[n].Dad].Len + 1;
|
|
if (bits > max_length)
|
|
bits = max_length, overflow++;
|
|
tree[n].Len = (ush) bits;
|
|
/* We overwrite tree[n].Dad which is no longer needed */
|
|
|
|
if (n > max_code)
|
|
continue; /* not a leaf node */
|
|
|
|
bl_count[bits]++;
|
|
xbits = 0;
|
|
if (n >= base)
|
|
xbits = extra[n - base];
|
|
f = tree[n].Freq;
|
|
opt_len += (ulg) f *(bits + xbits);
|
|
|
|
if (stree)
|
|
static_len += (ulg) f *(stree[n].Len + xbits);
|
|
}
|
|
if (overflow == 0)
|
|
return;
|
|
|
|
Trace((stderr, "\nbit length overflow\n"));
|
|
/* This happens for example on obj2 and pic of the Calgary corpus */
|
|
|
|
/* Find the first bit length which could increase: */
|
|
do {
|
|
bits = max_length - 1;
|
|
while (bl_count[bits] == 0)
|
|
bits--;
|
|
bl_count[bits]--; /* move one leaf down the tree */
|
|
bl_count[bits + 1] += 2; /* move one overflow item as its brother */
|
|
bl_count[max_length]--;
|
|
/* The brother of the overflow item also moves one step up,
|
|
* but this does not affect bl_count[max_length]
|
|
*/
|
|
overflow -= 2;
|
|
} while (overflow > 0);
|
|
|
|
/* Now recompute all bit lengths, scanning in increasing frequency.
|
|
* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
|
|
* lengths instead of fixing only the wrong ones. This idea is taken
|
|
* from 'ar' written by Haruhiko Okumura.)
|
|
*/
|
|
for (bits = max_length; bits != 0; bits--) {
|
|
n = bl_count[bits];
|
|
while (n != 0) {
|
|
m = heap[--h];
|
|
if (m > max_code)
|
|
continue;
|
|
if (tree[m].Len != (unsigned) bits) {
|
|
Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len,
|
|
bits));
|
|
opt_len +=
|
|
((long) bits - (long) tree[m].Len) * (long) tree[m].Freq;
|
|
tree[m].Len = (ush) bits;
|
|
}
|
|
n--;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Generate the codes for a given tree and bit counts (which need not be
|
|
* optimal).
|
|
* IN assertion: the array bl_count contains the bit length statistics for
|
|
* the given tree and the field len is set for all tree elements.
|
|
* OUT assertion: the field code is set for all tree elements of non
|
|
* zero code length.
|
|
*/
|
|
static void gen_codes(ct_data * tree, int max_code)
|
|
{
|
|
ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
|
|
ush code = 0; /* running code value */
|
|
int bits; /* bit index */
|
|
int n; /* code index */
|
|
|
|
/* The distribution counts are first used to generate the code values
|
|
* without bit reversal.
|
|
*/
|
|
for (bits = 1; bits <= MAX_BITS; bits++) {
|
|
next_code[bits] = code = (code + bl_count[bits - 1]) << 1;
|
|
}
|
|
/* Check that the bit counts in bl_count are consistent. The last code
|
|
* must be all ones.
|
|
*/
|
|
Assert(code + bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
|
|
"inconsistent bit counts");
|
|
Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
int len = tree[n].Len;
|
|
|
|
if (len == 0)
|
|
continue;
|
|
/* Now reverse the bits */
|
|
tree[n].Code = bi_reverse(next_code[len]++, len);
|
|
|
|
Tracec(tree != static_ltree,
|
|
(stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
|
|
(isgraph(n) ? n : ' '), len, tree[n].Code,
|
|
next_code[len] - 1));
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Construct one Huffman tree and assigns the code bit strings and lengths.
|
|
* Update the total bit length for the current block.
|
|
* IN assertion: the field freq is set for all tree elements.
|
|
* OUT assertions: the fields len and code are set to the optimal bit length
|
|
* and corresponding code. The length opt_len is updated; static_len is
|
|
* also updated if stree is not null. The field max_code is set.
|
|
*/
|
|
static void build_tree(tree_desc * desc)
|
|
{
|
|
ct_data *tree = desc->dyn_tree;
|
|
ct_data *stree = desc->static_tree;
|
|
int elems = desc->elems;
|
|
int n, m; /* iterate over heap elements */
|
|
int max_code = -1; /* largest code with non zero frequency */
|
|
int node = elems; /* next internal node of the tree */
|
|
|
|
/* Construct the initial heap, with least frequent element in
|
|
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
|
|
* heap[0] is not used.
|
|
*/
|
|
heap_len = 0, heap_max = HEAP_SIZE;
|
|
|
|
for (n = 0; n < elems; n++) {
|
|
if (tree[n].Freq != 0) {
|
|
heap[++heap_len] = max_code = n;
|
|
depth[n] = 0;
|
|
} else {
|
|
tree[n].Len = 0;
|
|
}
|
|
}
|
|
|
|
/* The pkzip format requires that at least one distance code exists,
|
|
* and that at least one bit should be sent even if there is only one
|
|
* possible code. So to avoid special checks later on we force at least
|
|
* two codes of non zero frequency.
|
|
*/
|
|
while (heap_len < 2) {
|
|
int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
|
|
|
|
tree[new].Freq = 1;
|
|
depth[new] = 0;
|
|
opt_len--;
|
|
if (stree)
|
|
static_len -= stree[new].Len;
|
|
/* new is 0 or 1 so it does not have extra bits */
|
|
}
|
|
desc->max_code = max_code;
|
|
|
|
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
|
|
* establish sub-heaps of increasing lengths:
|
|
*/
|
|
for (n = heap_len / 2; n >= 1; n--)
|
|
pqdownheap(tree, n);
|
|
|
|
/* Construct the Huffman tree by repeatedly combining the least two
|
|
* frequent nodes.
|
|
*/
|
|
do {
|
|
pqremove(tree, n); /* n = node of least frequency */
|
|
m = heap[SMALLEST]; /* m = node of next least frequency */
|
|
|
|
heap[--heap_max] = n; /* keep the nodes sorted by frequency */
|
|
heap[--heap_max] = m;
|
|
|
|
/* Create a new node father of n and m */
|
|
tree[node].Freq = tree[n].Freq + tree[m].Freq;
|
|
depth[node] = (uch) (MAX(depth[n], depth[m]) + 1);
|
|
tree[n].Dad = tree[m].Dad = (ush) node;
|
|
#ifdef DUMP_BL_TREE
|
|
if (tree == bl_tree) {
|
|
bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
|
|
node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
|
|
}
|
|
#endif
|
|
/* and insert the new node in the heap */
|
|
heap[SMALLEST] = node++;
|
|
pqdownheap(tree, SMALLEST);
|
|
|
|
} while (heap_len >= 2);
|
|
|
|
heap[--heap_max] = heap[SMALLEST];
|
|
|
|
/* At this point, the fields freq and dad are set. We can now
|
|
* generate the bit lengths.
|
|
*/
|
|
gen_bitlen((tree_desc *) desc);
|
|
|
|
/* The field len is now set, we can generate the bit codes */
|
|
gen_codes((ct_data *) tree, max_code);
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Scan a literal or distance tree to determine the frequencies of the codes
|
|
* in the bit length tree. Updates opt_len to take into account the repeat
|
|
* counts. (The contribution of the bit length codes will be added later
|
|
* during the construction of bl_tree.)
|
|
*/
|
|
static void scan_tree(ct_data * tree, int max_code)
|
|
{
|
|
int n; /* iterates over all tree elements */
|
|
int prevlen = -1; /* last emitted length */
|
|
int curlen; /* length of current code */
|
|
int nextlen = tree[0].Len; /* length of next code */
|
|
int count = 0; /* repeat count of the current code */
|
|
int max_count = 7; /* max repeat count */
|
|
int min_count = 4; /* min repeat count */
|
|
|
|
if (nextlen == 0)
|
|
max_count = 138, min_count = 3;
|
|
tree[max_code + 1].Len = (ush) 0xffff; /* guard */
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
curlen = nextlen;
|
|
nextlen = tree[n + 1].Len;
|
|
if (++count < max_count && curlen == nextlen) {
|
|
continue;
|
|
} else if (count < min_count) {
|
|
bl_tree[curlen].Freq += count;
|
|
} else if (curlen != 0) {
|
|
if (curlen != prevlen)
|
|
bl_tree[curlen].Freq++;
|
|
bl_tree[REP_3_6].Freq++;
|
|
} else if (count <= 10) {
|
|
bl_tree[REPZ_3_10].Freq++;
|
|
} else {
|
|
bl_tree[REPZ_11_138].Freq++;
|
|
}
|
|
count = 0;
|
|
prevlen = curlen;
|
|
if (nextlen == 0) {
|
|
max_count = 138, min_count = 3;
|
|
} else if (curlen == nextlen) {
|
|
max_count = 6, min_count = 3;
|
|
} else {
|
|
max_count = 7, min_count = 4;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Send a literal or distance tree in compressed form, using the codes in
|
|
* bl_tree.
|
|
*/
|
|
static void send_tree(ct_data * tree, int max_code)
|
|
{
|
|
int n; /* iterates over all tree elements */
|
|
int prevlen = -1; /* last emitted length */
|
|
int curlen; /* length of current code */
|
|
int nextlen = tree[0].Len; /* length of next code */
|
|
int count = 0; /* repeat count of the current code */
|
|
int max_count = 7; /* max repeat count */
|
|
int min_count = 4; /* min repeat count */
|
|
|
|
/* tree[max_code+1].Len = -1; *//* guard already set */
|
|
if (nextlen == 0)
|
|
max_count = 138, min_count = 3;
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
curlen = nextlen;
|
|
nextlen = tree[n + 1].Len;
|
|
if (++count < max_count && curlen == nextlen) {
|
|
continue;
|
|
} else if (count < min_count) {
|
|
do {
|
|
send_code(curlen, bl_tree);
|
|
} while (--count != 0);
|
|
|
|
} else if (curlen != 0) {
|
|
if (curlen != prevlen) {
|
|
send_code(curlen, bl_tree);
|
|
count--;
|
|
}
|
|
Assert(count >= 3 && count <= 6, " 3_6?");
|
|
send_code(REP_3_6, bl_tree);
|
|
send_bits(count - 3, 2);
|
|
|
|
} else if (count <= 10) {
|
|
send_code(REPZ_3_10, bl_tree);
|
|
send_bits(count - 3, 3);
|
|
|
|
} else {
|
|
send_code(REPZ_11_138, bl_tree);
|
|
send_bits(count - 11, 7);
|
|
}
|
|
count = 0;
|
|
prevlen = curlen;
|
|
if (nextlen == 0) {
|
|
max_count = 138, min_count = 3;
|
|
} else if (curlen == nextlen) {
|
|
max_count = 6, min_count = 3;
|
|
} else {
|
|
max_count = 7, min_count = 4;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Construct the Huffman tree for the bit lengths and return the index in
|
|
* bl_order of the last bit length code to send.
|
|
*/
|
|
static int build_bl_tree()
|
|
{
|
|
int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
|
/* Determine the bit length frequencies for literal and distance trees */
|
|
scan_tree((ct_data *) dyn_ltree, l_desc.max_code);
|
|
scan_tree((ct_data *) dyn_dtree, d_desc.max_code);
|
|
|
|
/* Build the bit length tree: */
|
|
build_tree((tree_desc *) (&bl_desc));
|
|
/* opt_len now includes the length of the tree representations, except
|
|
* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
|
|
*/
|
|
|
|
/* Determine the number of bit length codes to send. The pkzip format
|
|
* requires that at least 4 bit length codes be sent. (appnote.txt says
|
|
* 3 but the actual value used is 4.)
|
|
*/
|
|
for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
|
|
if (bl_tree[bl_order[max_blindex]].Len != 0)
|
|
break;
|
|
}
|
|
/* Update opt_len to include the bit length tree and counts */
|
|
opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
|
|
Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len));
|
|
|
|
return max_blindex;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Send the header for a block using dynamic Huffman trees: the counts, the
|
|
* lengths of the bit length codes, the literal tree and the distance tree.
|
|
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
|
|
*/
|
|
static void send_all_trees(int lcodes, int dcodes, int blcodes)
|
|
{
|
|
int rank; /* index in bl_order */
|
|
|
|
Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
|
|
Assert(lcodes <= L_CODES && dcodes <= D_CODES
|
|
&& blcodes <= BL_CODES, "too many codes");
|
|
Tracev((stderr, "\nbl counts: "));
|
|
send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
|
|
send_bits(dcodes - 1, 5);
|
|
send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
|
|
for (rank = 0; rank < blcodes; rank++) {
|
|
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
|
|
send_bits(bl_tree[bl_order[rank]].Len, 3);
|
|
}
|
|
Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
|
|
|
|
send_tree((ct_data *) dyn_ltree, lcodes - 1); /* send the literal tree */
|
|
Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
|
|
|
|
send_tree((ct_data *) dyn_dtree, dcodes - 1); /* send the distance tree */
|
|
Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Determine the best encoding for the current block: dynamic trees, static
|
|
* trees or store, and output the encoded block to the zip file. This function
|
|
* returns the total compressed length for the file so far.
|
|
*/
|
|
static ulg flush_block(char *buf, ulg stored_len, int eof)
|
|
{
|
|
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
|
|
int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
|
flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
|
|
|
|
/* Check if the file is ascii or binary */
|
|
if (*file_type == (ush) UNKNOWN)
|
|
set_file_type();
|
|
|
|
/* Construct the literal and distance trees */
|
|
build_tree((tree_desc *) (&l_desc));
|
|
Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
|
|
|
|
build_tree((tree_desc *) (&d_desc));
|
|
Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len));
|
|
/* At this point, opt_len and static_len are the total bit lengths of
|
|
* the compressed block data, excluding the tree representations.
|
|
*/
|
|
|
|
/* Build the bit length tree for the above two trees, and get the index
|
|
* in bl_order of the last bit length code to send.
|
|
*/
|
|
max_blindex = build_bl_tree();
|
|
|
|
/* Determine the best encoding. Compute first the block length in bytes */
|
|
opt_lenb = (opt_len + 3 + 7) >> 3;
|
|
static_lenb = (static_len + 3 + 7) >> 3;
|
|
|
|
Trace((stderr,
|
|
"\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
|
|
opt_lenb, opt_len, static_lenb, static_len, stored_len,
|
|
last_lit, last_dist));
|
|
|
|
if (static_lenb <= opt_lenb)
|
|
opt_lenb = static_lenb;
|
|
|
|
/* If compression failed and this is the first and last block,
|
|
* and if the zip file can be seeked (to rewrite the local header),
|
|
* the whole file is transformed into a stored file:
|
|
*/
|
|
if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) {
|
|
/* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
|
|
if (buf == (char *) 0)
|
|
bb_error_msg("block vanished");
|
|
|
|
copy_block(buf, (unsigned) stored_len, 0); /* without header */
|
|
compressed_len = stored_len << 3;
|
|
*file_method = STORED;
|
|
|
|
} else if (stored_len + 4 <= opt_lenb && buf != (char *) 0) {
|
|
/* 4: two words for the lengths */
|
|
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
|
|
* Otherwise we can't have processed more than WSIZE input bytes since
|
|
* the last block flush, because compression would have been
|
|
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
|
|
* transform a block into a stored block.
|
|
*/
|
|
send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
|
|
compressed_len = (compressed_len + 3 + 7) & ~7L;
|
|
compressed_len += (stored_len + 4) << 3;
|
|
|
|
copy_block(buf, (unsigned) stored_len, 1); /* with header */
|
|
|
|
} else if (static_lenb == opt_lenb) {
|
|
send_bits((STATIC_TREES << 1) + eof, 3);
|
|
compress_block((ct_data *) static_ltree, (ct_data *) static_dtree);
|
|
compressed_len += 3 + static_len;
|
|
} else {
|
|
send_bits((DYN_TREES << 1) + eof, 3);
|
|
send_all_trees(l_desc.max_code + 1, d_desc.max_code + 1,
|
|
max_blindex + 1);
|
|
compress_block((ct_data *) dyn_ltree, (ct_data *) dyn_dtree);
|
|
compressed_len += 3 + opt_len;
|
|
}
|
|
Assert(compressed_len == bits_sent, "bad compressed size");
|
|
init_block();
|
|
|
|
if (eof) {
|
|
bi_windup();
|
|
compressed_len += 7; /* align on byte boundary */
|
|
}
|
|
Tracev((stderr, "\ncomprlen %lu(%lu) ", compressed_len >> 3,
|
|
compressed_len - 7 * eof));
|
|
|
|
return compressed_len >> 3;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Save the match info and tally the frequency counts. Return true if
|
|
* the current block must be flushed.
|
|
*/
|
|
static int ct_tally(int dist, int lc)
|
|
{
|
|
l_buf[last_lit++] = (uch) lc;
|
|
if (dist == 0) {
|
|
/* lc is the unmatched char */
|
|
dyn_ltree[lc].Freq++;
|
|
} else {
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
dist--; /* dist = match distance - 1 */
|
|
Assert((ush) dist < (ush) MAX_DIST &&
|
|
(ush) lc <= (ush) (MAX_MATCH - MIN_MATCH) &&
|
|
(ush) d_code(dist) < (ush) D_CODES, "ct_tally: bad match");
|
|
|
|
dyn_ltree[length_code[lc] + LITERALS + 1].Freq++;
|
|
dyn_dtree[d_code(dist)].Freq++;
|
|
|
|
d_buf[last_dist++] = (ush) dist;
|
|
flags |= flag_bit;
|
|
}
|
|
flag_bit <<= 1;
|
|
|
|
/* Output the flags if they fill a byte: */
|
|
if ((last_lit & 7) == 0) {
|
|
flag_buf[last_flags++] = flags;
|
|
flags = 0, flag_bit = 1;
|
|
}
|
|
/* Try to guess if it is profitable to stop the current block here */
|
|
if ((last_lit & 0xfff) == 0) {
|
|
/* Compute an upper bound for the compressed length */
|
|
ulg out_length = (ulg) last_lit * 8L;
|
|
ulg in_length = (ulg) strstart - block_start;
|
|
int dcode;
|
|
|
|
for (dcode = 0; dcode < D_CODES; dcode++) {
|
|
out_length +=
|
|
(ulg) dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
|
|
}
|
|
out_length >>= 3;
|
|
Trace((stderr,
|
|
"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
|
|
last_lit, last_dist, in_length, out_length,
|
|
100L - out_length * 100L / in_length));
|
|
if (last_dist < last_lit / 2 && out_length < in_length / 2)
|
|
return 1;
|
|
}
|
|
return (last_lit == LIT_BUFSIZE - 1 || last_dist == DIST_BUFSIZE);
|
|
/* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
|
|
* on 16 bit machines and because stored blocks are restricted to
|
|
* 64K-1 bytes.
|
|
*/
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Send the block data compressed using the given Huffman trees
|
|
*/
|
|
static void compress_block(ct_data * ltree, ct_data * dtree)
|
|
{
|
|
unsigned dist; /* distance of matched string */
|
|
int lc; /* match length or unmatched char (if dist == 0) */
|
|
unsigned lx = 0; /* running index in l_buf */
|
|
unsigned dx = 0; /* running index in d_buf */
|
|
unsigned fx = 0; /* running index in flag_buf */
|
|
uch flag = 0; /* current flags */
|
|
unsigned code; /* the code to send */
|
|
int extra; /* number of extra bits to send */
|
|
|
|
if (last_lit != 0)
|
|
do {
|
|
if ((lx & 7) == 0)
|
|
flag = flag_buf[fx++];
|
|
lc = l_buf[lx++];
|
|
if ((flag & 1) == 0) {
|
|
send_code(lc, ltree); /* send a literal byte */
|
|
Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
|
|
} else {
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
code = length_code[lc];
|
|
send_code(code + LITERALS + 1, ltree); /* send the length code */
|
|
extra = extra_lbits[code];
|
|
if (extra != 0) {
|
|
lc -= base_length[code];
|
|
send_bits(lc, extra); /* send the extra length bits */
|
|
}
|
|
dist = d_buf[dx++];
|
|
/* Here, dist is the match distance - 1 */
|
|
code = d_code(dist);
|
|
Assert(code < D_CODES, "bad d_code");
|
|
|
|
send_code(code, dtree); /* send the distance code */
|
|
extra = extra_dbits[code];
|
|
if (extra != 0) {
|
|
dist -= base_dist[code];
|
|
send_bits(dist, extra); /* send the extra distance bits */
|
|
}
|
|
} /* literal or match pair ? */
|
|
flag >>= 1;
|
|
} while (lx < last_lit);
|
|
|
|
send_code(END_BLOCK, ltree);
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Set the file type to ASCII or BINARY, using a crude approximation:
|
|
* binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise.
|
|
* IN assertion: the fields freq of dyn_ltree are set and the total of all
|
|
* frequencies does not exceed 64K (to fit in an int on 16 bit machines).
|
|
*/
|
|
static void set_file_type()
|
|
{
|
|
int n = 0;
|
|
unsigned ascii_freq = 0;
|
|
unsigned bin_freq = 0;
|
|
|
|
while (n < 7)
|
|
bin_freq += dyn_ltree[n++].Freq;
|
|
while (n < 128)
|
|
ascii_freq += dyn_ltree[n++].Freq;
|
|
while (n < LITERALS)
|
|
bin_freq += dyn_ltree[n++].Freq;
|
|
*file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII;
|
|
if (*file_type == BINARY && translate_eol) {
|
|
bb_error_msg("-l used on binary file");
|
|
}
|
|
}
|
|
|
|
/* zip.c -- compress files to the gzip or pkzip format
|
|
* Copyright (C) 1992-1993 Jean-loup Gailly
|
|
* This is free software; you can redistribute it and/or modify it under the
|
|
* terms of the GNU General Public License, see the file COPYING.
|
|
*/
|
|
|
|
|
|
static ulg crc; /* crc on uncompressed file data */
|
|
static long header_bytes; /* number of bytes in gzip header */
|
|
|
|
static void put_long(ulg n)
|
|
{
|
|
put_short((n) & 0xffff);
|
|
put_short(((ulg) (n)) >> 16);
|
|
}
|
|
|
|
/* put_header_byte is used for the compressed output
|
|
* - for the initial 4 bytes that can't overflow the buffer.
|
|
*/
|
|
#define put_header_byte(c) {outbuf[outcnt++]=(uch)(c);}
|
|
|
|
/* ===========================================================================
|
|
* Deflate in to out.
|
|
* IN assertions: the input and output buffers are cleared.
|
|
* The variables time_stamp and save_orig_name are initialized.
|
|
*/
|
|
static int zip(int in, int out)
|
|
{
|
|
uch my_flags = 0; /* general purpose bit flags */
|
|
ush attr = 0; /* ascii/binary flag */
|
|
ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
|
|
|
|
ifd = in;
|
|
ofd = out;
|
|
outcnt = 0;
|
|
|
|
/* Write the header to the gzip file. See algorithm.doc for the format */
|
|
|
|
|
|
method = DEFLATED;
|
|
put_header_byte(GZIP_MAGIC[0]); /* magic header */
|
|
put_header_byte(GZIP_MAGIC[1]);
|
|
put_header_byte(DEFLATED); /* compression method */
|
|
|
|
put_header_byte(my_flags); /* general flags */
|
|
put_long(time_stamp);
|
|
|
|
/* Write deflated file to zip file */
|
|
crc = updcrc(0, 0);
|
|
|
|
bi_init(out);
|
|
ct_init(&attr, &method);
|
|
lm_init(&deflate_flags);
|
|
|
|
put_byte((uch) deflate_flags); /* extra flags */
|
|
put_byte(OS_CODE); /* OS identifier */
|
|
|
|
header_bytes = (long) outcnt;
|
|
|
|
(void) deflate();
|
|
|
|
/* Write the crc and uncompressed size */
|
|
put_long(crc);
|
|
put_long(isize);
|
|
header_bytes += 2 * sizeof(long);
|
|
|
|
flush_outbuf();
|
|
return OK;
|
|
}
|
|
|
|
|
|
/* ===========================================================================
|
|
* Read a new buffer from the current input file, perform end-of-line
|
|
* translation, and update the crc and input file size.
|
|
* IN assertion: size >= 2 (for end-of-line translation)
|
|
*/
|
|
static int file_read(char *buf, unsigned size)
|
|
{
|
|
unsigned len;
|
|
|
|
Assert(insize == 0, "inbuf not empty");
|
|
|
|
len = read(ifd, buf, size);
|
|
if (len == (unsigned) (-1) || len == 0)
|
|
return (int) len;
|
|
|
|
crc = updcrc((uch *) buf, len);
|
|
isize += (ulg) len;
|
|
return (int) len;
|
|
}
|
|
|
|
/* ===========================================================================
|
|
* Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
|
|
* (used for the compressed data only)
|
|
*/
|
|
static void flush_outbuf()
|
|
{
|
|
if (outcnt == 0)
|
|
return;
|
|
|
|
write_buf(ofd, (char *) outbuf, outcnt);
|
|
outcnt = 0;
|
|
}
|