www.pudn.com > gzip_win.zip > unzip.c
/* 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 RCSID
static char rcsid[] = "$Id: unzip.c,v 0.13 1993/06/10 13:29:00 jloup Exp $";
#endif
#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(in)
int in; /* input file descriptors */
{
uch *h = inbuf + inptr; /* first local header */
ifd = in;
/* 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(in, out)
int in, out; /* 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 */
ifd = in;
ofd = out;
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");
}
/* Check if there are more entries in a pkzip file */
if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
if (to_stdout) {
WARN((stderr,
"%s: %s has more than one entry--rest ignored\n",
progname, ifname));
} else {
/* Don't destroy the input zip file */
fprintf(stderr,
"%s: %s has more than one entry -- unchanged\n",
progname, ifname);
exit_code = ERROR;
ext_header = pkzip = 0;
return ERROR;
}
}
ext_header = pkzip = 0; /* for next file */
return OK;
}