/* unzip.c -- decompress files in 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. * * The code in this file is derived from the file funzip.c written * and put in the public domain by Mark Adler. *//*   This version can extract files in gzip or pkzip format.   For the latter, only the first entry is extracted, and it has to be   either deflated or stored. */#ifdef RCSIDstatic char rcsid[] = "$Id: unzip.c,v 0.13 1993/06/10 13:29:00 jloup Exp $";#endif#define RAND_HEAD_LEN  12#include "tailor.h"#include "gzip.h"#include "crypt.h"/* PKZIP header definitions */#define LOCSIG 0x04034b50L      /* four-byte lead-in (lsb first) */#define LOCFLG 6                /* offset of bit flag */#define  CRPFLG 1               /*  bit for encrypted entry */#define  EXTFLG 8               /*  bit for extended local header */#define LOCHOW 8                /* offset of compression method */#define LOCTIM 10               /* file mod time (for decryption) */#define LOCCRC 14               /* offset of crc */#define LOCSIZ 18               /* offset of compressed size */#define LOCLEN 22               /* offset of uncompressed length */#define LOCFIL 26               /* offset of file name field length */#define LOCEXT 28               /* offset of extra field length */#define LOCHDR 30               /* size of local header, including sig */#define EXTHDR 16               /* size of extended local header, inc sig *//* Globals */int decrypt;        /* flag to turn on decryption */char *key;          /* not used--needed to link crypt.c */int pkzip = 0;      /* set for a pkzip file */int ext_header = 0; /* set if extended local header *//* =========================================================================== * Check zip file and advance inptr to the start of the compressed data. * Get ofname from the local header if necessary. */int check_zipfile(){    uch *h = inbuf + inptr; /* first local header */    /* Check validity of local header, and skip name and extra fields */    inptr += LOCHDR + SH(h + LOCFIL) + SH(h + LOCEXT);    if (inptr > insize || LG(h) != LOCSIG) {	fprintf(stderr, "\n%s: %s: not a valid zip file\n",		progname, ifname);	exit_code = ERROR;	return ERROR;    }    method = h[LOCHOW];    if (method != STORED && method != DEFLATED) {	fprintf(stderr,		"\n%s: %s: first entry not deflated or stored -- use unzip\n",		progname, ifname);	exit_code = ERROR;	return ERROR;    }    /* If entry encrypted, decrypt and validate encryption header */    if ((decrypt = h[LOCFLG] & CRPFLG) != 0) {	fprintf(stderr, "\n%s: %s: encrypted file -- use unzip\n",		progname, ifname);	exit_code = ERROR;	return ERROR;    }    /* Save flags for unzip() */    ext_header = (h[LOCFLG] & EXTFLG) != 0;    pkzip = 1;    /* Get ofname and time stamp from local header (to be done) */    return OK;}/* =========================================================================== * Unzip in to out.  This routine works on both gzip and pkzip files. * * IN assertions: the buffer inbuf contains already the beginning of *   the compressed data, from offsets inptr to insize-1 included. *   The magic header has already been checked. The output buffer is cleared. */int unzip(char *in, char *outprint)   /* input and output file descriptors */{    ulg orig_crc = 0;       /* original crc */    ulg orig_len = 0;       /* original uncompressed length */    int n;    uch buf[EXTHDR];        /* extended local header */    updcrc(NULL, 0);           /* initialize crc */    if (pkzip && !ext_header)     {  /* crc and length at the end otherwise */		orig_crc = LG(inbuf + LOCCRC);		orig_len = LG(inbuf + LOCLEN);    }    /* Decompress */    if (method == DEFLATED)  	{		int res = inflate();		if (res == 3) 		{			error("out of memory");		} 		else if (res != 0) 		{			error("invalid compressed data--format violated");		}		}		else if (pkzip && method == STORED) 		{			register ulg n = LG(inbuf + LOCLEN);			if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) 			{				fprintf(stderr, "len %ld, siz %ld\n", n, LG(inbuf + LOCSIZ));				error("invalid compressed data--length mismatch");			}			while (n--) 			{				uch c = (uch)get_byte();#ifdef CRYPT				if (decrypt) 					zdecode(c);#endif				put_ubyte(c);			}			flush_window();		}		else 		{			error("internal error, invalid method");		}    /* Get the crc and original length */		if (!pkzip) 		{        /* crc32  (see algorithm.doc)	 * uncompressed input size modulo 2^32         */			for (n = 0; n < 8; n++) 			{				buf[n] = (uch)get_byte(); /* may cause an error if EOF */			}			orig_crc = LG(buf);			orig_len = LG(buf+4);		}	 		else if (ext_header) 		{  /* If extended header, check it */	/* signature - 4bytes: 0x50 0x4b 0x07 0x08	 * CRC-32 value         * compressed size 4-bytes         * uncompressed size 4-bytes	 */			for (n = 0; n < EXTHDR; n++) 			{				buf[n] = (uch)get_byte(); /* may cause an error if EOF */			}			orig_crc = LG(buf+4);			orig_len = LG(buf+12);		}    /* Validate decompression */		if (orig_crc != updcrc(outbuf, 0)) 		{			error("invalid compressed data--crc error");		}		if (orig_len != (ulg)bytes_out) 		{			error("invalid compressed data--length error");		}    		ext_header = pkzip = 0;	 return OK;}