unzip.c

手机嵌入式Linux下可用的busybox源码

/* vi: set sw=4 ts=4: */
/*
 * gunzip implementation for busybox
 *
 * Based on GNU gzip v1.2.4 Copyright (C) 1992-1993 Jean-loup Gailly.
 *
 * Originally adjusted for busybox by Sven Rudolph <[e-mail]>
 * based on gzip sources
 *
 * Adjusted further by Erik Andersen <[e-mail]> to support
 * files as well as stdin/stdout, and to generally behave itself wrt
 * command line handling.
 *
 * General cleanup to better adhere to the style guide and make use of
 * standard busybox functions by Glenn McGrath <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 *
 * 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.
 */

#if 0
static char *license_msg[] = {
	"   Copyright (C) 1992-1993 Jean-loup Gailly",
	"   This program is free software; you can redistribute it and/or modify",
	"   it under the terms of the GNU General Public License as published by",
	"   the Free Software Foundation; either version 2, or (at your option)",
	"   any later version.",
	"",
	"   This program is distributed in the hope that it will be useful,",
	"   but WITHOUT ANY WARRANTY; without even the implied warranty of",
	"   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the",
	"   GNU General Public License for more details.",
	"",
	"   You should have received a copy of the GNU General Public License",
	"   along with this program; if not, write to the Free Software",
	"   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.",
	0
};
#endif

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include "libbb.h"

static FILE *in_file, *out_file;

/* these are freed by gz_close */
static unsigned char *window;
static unsigned long *crc_table;

static unsigned long crc; /* shift register contents */

/* Return codes from gzip */
static const int ERROR = 1;

/*
 * window size--must be a power of two, and
 *  at least 32K for zip's deflate method 
 */
static const int WSIZE = 0x8000;

/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
static const int BMAX = 16;		/* maximum bit length of any code (16 for explode) */
static const int N_MAX = 288;		/* maximum number of codes in any set */

static long bytes_out;		/* number of output bytes */
static unsigned long outcnt;	/* bytes in output buffer */

static unsigned hufts;		/* track memory usage */
static unsigned long bb;			/* bit buffer */
static unsigned bk;		/* bits in bit buffer */

typedef struct huft_s {
	unsigned char e;		/* number of extra bits or operation */
	unsigned char b;		/* number of bits in this code or subcode */
	union {
		unsigned short n;		/* literal, length base, or distance base */
		struct huft_s *t;	/* pointer to next level of table */
	} v;
} huft_t;

static const unsigned short mask_bits[] = {
	0x0000,
	0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
	0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
};

//static int error_number = 0;
/* ========================================================================
 * Signal and error handler.
 */
 
static void abort_gzip()
{
	error_msg("gzip aborted\n");
	exit(ERROR);
}

static void make_crc_table()
{
	unsigned long table_entry;      /* crc shift register */
	unsigned long poly = 0;      /* polynomial exclusive-or pattern */
	int i;                /* counter for all possible eight bit values */
	int k;                /* byte being shifted into crc apparatus */

	/* terms of polynomial defining this crc (except x^32): */
	static int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

	/* initial shift register value */
	crc = 0xffffffffL;	
	crc_table = (unsigned long *) malloc(256 * sizeof(unsigned long));

	/* Make exclusive-or pattern from polynomial (0xedb88320) */
	for (i = 0; i < sizeof(p)/sizeof(int); i++)
		poly |= 1L << (31 - p[i]);

	/* Compute and print table of CRC's, five per line */
	for (i = 0; i < 256; i++) {
		table_entry = i;
	   /* The idea to initialize the register with the byte instead of
	     * zero was stolen from Haruhiko Okumura's ar002
	     */
		for (k = 8; k; k--) {
			table_entry = table_entry & 1 ? (table_entry >> 1) ^ poly : table_entry >> 1;
		}
		crc_table[i]=table_entry;
	}
}

/* ===========================================================================
 * Write the output window window[0..outcnt-1] and update crc and bytes_out.
 * (Used for the decompressed data only.)
 */
static void flush_window(void)
{
	int n;

	if (outcnt == 0)
		return;

	for (n = 0; n < outcnt; n++) {
		crc = crc_table[((int) crc ^ (window[n])) & 0xff] ^ (crc >> 8);
	}

	if (fwrite(window, 1, outcnt, out_file) != outcnt) {
		error_msg_and_die("Couldnt write");
	}
	bytes_out += (unsigned long) outcnt;
	outcnt = 0;
}

/*
 * Free the malloc'ed tables built by huft_build(), which makes a linked
 * list of the tables it made, with the links in a dummy first entry of
 * each table. 
 * t: table to free
 */
static int huft_free(huft_t *t)
{
	huft_t *p, *q;

	/* Go through linked list, freeing from the malloced (t[-1]) address. */
	p = t;
	while (p != (huft_t *) NULL) {
		q = (--p)->v.t;
		free((char *) p);
		p = q;
	}
	return 0;
}

/* Given a list of code lengths and a maximum table size, make a set of
 * tables to decode that set of codes.  Return zero on success, one if
 * the given code set is incomplete (the tables are still built in this
 * case), two if the input is invalid (all zero length codes or an
 * oversubscribed set of lengths), and three if not enough memory.
 *
 * b:	code lengths in bits (all assumed <= BMAX)
 * n:	number of codes (assumed <= N_MAX)
 * s:	number of simple-valued codes (0..s-1)
 * d:	list of base values for non-simple codes
 * e:	list of extra bits for non-simple codes
 * t:	result: starting table
 * m:	maximum lookup bits, returns actual
 */
static int huft_build(unsigned int *b, const unsigned int n, const unsigned int s, 
	const unsigned short *d, const unsigned short *e, huft_t **t, int *m)
{
	unsigned a;		/* counter for codes of length k */
	unsigned c[BMAX + 1];	/* bit length count table */
	unsigned f;		/* i repeats in table every f entries */
	int g;			/* maximum code length */
	int h;			/* table level */
	register unsigned i;	/* counter, current code */
	register unsigned j;	/* counter */
	register int k;		/* number of bits in current code */
	int l;			/* bits per table (returned in m) */
	register unsigned *p;		/* pointer into c[], b[], or v[] */
	register huft_t *q;	/* points to current table */
	huft_t r;		/* table entry for structure assignment */
	huft_t *u[BMAX];	/* table stack */
	unsigned v[N_MAX];	/* values in order of bit length */
	register int w;		/* bits before this table == (l * h) */
	unsigned x[BMAX + 1];	/* bit offsets, then code stack */
	unsigned *xp;		/* pointer into x */
	int y;			/* number of dummy codes added */
	unsigned z;		/* number of entries in current table */

	/* Generate counts for each bit length */
	memset ((void *)(c), 0, sizeof(c));
	p = b;
	i = n;
	do {
		c[*p]++;	/* assume all entries <= BMAX */
		p++;		/* Can't combine with above line (Solaris bug) */
	} while (--i);
	if (c[0] == n) {	/* null input--all zero length codes */
		*t = (huft_t *) NULL;
		*m = 0;
		return 0;
	}

	/* Find minimum and maximum length, bound *m by those */
	l = *m;
	for (j = 1; j <= BMAX; j++)
		if (c[j])
			break;
	k = j;				/* minimum code length */
	if ((unsigned) l < j)
		l = j;
	for (i = BMAX; i; i--)
		if (c[i])
			break;
	g = i;				/* maximum code length */
	if ((unsigned) l > i)
		l = i;
	*m = l;

	/* Adjust last length count to fill out codes, if needed */
	for (y = 1 << j; j < i; j++, y <<= 1)
		if ((y -= c[j]) < 0)
			return 2;	/* bad input: more codes than bits */
	if ((y -= c[i]) < 0)
		return 2;
	c[i] += y;

	/* Generate starting offsets into the value table for each length */
	x[1] = j = 0;
	p = c + 1;
	xp = x + 2;
	while (--i) {			/* note that i == g from above */
		*xp++ = (j += *p++);
	}

	/* Make a table of values in order of bit lengths */
	p = b;
	i = 0;
	do {
		if ((j = *p++) != 0)
			v[x[j]++] = i;
	} while (++i < n);

	/* Generate the Huffman codes and for each, make the table entries */
	x[0] = i = 0;			/* first Huffman code is zero */
	p = v;				/* grab values in bit order */
	h = -1;				/* no tables yet--level -1 */
	w = -l;				/* bits decoded == (l * h) */
	u[0] = (huft_t *) NULL;	/* just to keep compilers happy */
	q = (huft_t *) NULL;	/* ditto */
	z = 0;				/* ditto */

	/* go through the bit lengths (k already is bits in shortest code) */
	for (; k <= g; k++) {
		a = c[k];
		while (a--) {
			/* here i is the Huffman code of length k bits for value *p */
			/* make tables up to required level */
			while (k > w + l) {
				h++;
				w += l;		/* previous table always l bits */

				/* compute minimum size table less than or equal to l bits */
				z = (z = g - w) > (unsigned) l ? l : z;	/* upper limit on table size */
				if ((f = 1 << (j = k - w)) > a + 1) {	/* try a k-w bit table *//* too few codes for k-w bit table */
					f -= a + 1;	/* deduct codes from patterns left */
					xp = c + k;
					while (++j < z) {	/* try smaller tables up to z bits */
						if ((f <<= 1) <= *++xp)
							break;	/* enough codes to use up j bits */
						f -= *xp;	/* else deduct codes from patterns */
					}
				}
				z = 1 << j;		/* table entries for j-bit table */

				/* allocate and link in new table */
				if ((q = (huft_t *) xmalloc((z + 1) * sizeof(huft_t))) == NULL) {
					if (h) {
						huft_free(u[0]);
					}
					return 3;	/* not enough memory */
				}
				hufts += z + 1;	/* track memory usage */
				*t = q + 1;		/* link to list for huft_free() */
				*(t = &(q->v.t)) = NULL;
				u[h] = ++q;		/* table starts after link */

				/* connect to last table, if there is one */
				if (h) {
					x[h] = i;	/* save pattern for backing up */
					r.b = (unsigned char) l;	/* bits to dump before this table */
					r.e = (unsigned char) (16 + j);	/* bits in this table */
					r.v.t = q;	/* pointer to this table */
					j = i >> (w - l);	/* (get around Turbo C bug) */
					u[h - 1][j] = r;	/* connect to last table */
				}
			}

			/* set up table entry in r */
			r.b = (unsigned char) (k - w);
			if (p >= v + n)
				r.e = 99;		/* out of values--invalid code */
			else if (*p < s) {
				r.e = (unsigned char) (*p < 256 ? 16 : 15);	/* 256 is end-of-block code */
				r.v.n = (unsigned short) (*p);	/* simple code is just the value */
				p++;			/* one compiler does not like *p++ */
			} else {
				r.e = (unsigned char) e[*p - s];	/* non-simple--look up in lists */
				r.v.n = d[*p++ - s];
			}

			/* fill code-like entries with r */
			f = 1 << (k - w);
			for (j = i >> w; j < z; j += f)
				q[j] = r;

			/* backwards increment the k-bit code i */