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/* unzip.c -- decompress files in gzip or pkzip format.
* Copyright (C) 1992-1993 Jean-loup Gailly
*
* Adapted for Linux booting by Hannu Savolainen 1993
*
* 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.
*/
#include "gzip.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 pkzip = 0; /* set for a pkzip file */
int extended = 0; /* set if extended local header */
/*
* 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.
*/
void unzip(in, out)
int in, out; /* input and output file descriptors */
{
unsigned long orig_crc = 0; /* original crc */
unsigned long orig_len = 0; /* original uncompressed length */
int n;
unsigned char buf[EXTHDR]; /* extended local header */
/* ifd = in;
ofd = out; */
updcrc(NULL, 0); /* initialize crc */
if (pkzip && !extended) { /* 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) {
unzip_error("out of memory");
} else if (res != 0) {
unzip_error("invalid compressed format");
}
} else if (pkzip && method == STORED) {
register unsigned long n = LG(inbuf + LOCLEN);
if (n != LG(inbuf + LOCSIZ)) {
unzip_error("length mismatch");
}
while (n--) {
unsigned char c = get_byte();
put_char(c);
}
} else {
unzip_error("internal error, invalid method");
}
/* Get the crc and original length */
#ifdef DEBUG
printf("getting CRC and length\n");
#endif
if (!pkzip) {
/* crc32 (see algorithm.doc)
* uncompressed input size modulo 2^32
*/
for (n = 0; n < 8; n++) {
buf[n] = get_byte(); /* may cause an error if EOF */
#ifdef DEBUG
printf("nonext: doing CRC, get_byte (ptr %d) returned %d\n",
inptr, buf[n]);
#endif
}
orig_crc = LG(buf);
orig_len = LG(buf+4);
} else if (extended) { /* 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] = get_byte(); /* may cause an error if EOF */
#ifdef DEBUG
printf("ext: doing CRC, get_byte returned %d\n", buf[n]);
#endif
}
orig_crc = LG(buf+4);
orig_len = LG(buf+12);
}
/* Validate decompression */
if (orig_crc != updcrc(buf, 0)) {
unzip_error("crc error");
}
if (orig_len != bytes_out) {
unzip_error("length error");
}
/* Check if there are more entries in a pkzip file */
if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
unzip_error("zip file has more than one entry");
}
extended = pkzip = 0; /* for next file */
}
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