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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
* Adapted for FreeBSD booting by Serge Vakulenko
*
* 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"
#include <sys/types.h>
#include <sys/inflate.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 */
int pkzip; /* set for a pkzip file */
int extended; /* set if extended local header */
/* Macros for getting two-byte and four-byte header values */
#define SH(p) ((ushort)(uchar)((p)[0]) | ((ushort)(uchar)((p)[1]) << 8))
#define LG(p) ((ulong)(SH(p)) | ((ulong)(SH((p)+2)) << 16))
/*
* Check zip file and advance inptr to the start of the compressed data.
* Get ofname from the local header if necessary.
*/
void check_zipfile()
{
uchar *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)
error("input not a zip");
method = h[LOCHOW];
if (method != STORED && method != DEFLATED)
error("first entry not deflated or stored--can't extract");
/* If entry encrypted, decrypt and validate encryption header */
if (h[LOCFLG] & CRPFLG)
error("encrypted file");
/* Save flags for unzip() */
extended = (h[LOCFLG] & EXTFLG) != 0;
pkzip = 1;
}
int
Flush (void *nu, u_char *buf, u_long cnt)
{
outcnt = cnt;
flush_window();
return 0;
}
int
NextByte (void *nu)
{
return ((int) get_byte ());
}
struct inflate infl; /* put it into the BSS */
/*
* 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()
{
ulong orig_crc = 0; /* original crc */
ulong orig_len = 0; /* original uncompressed length */
uchar buf[EXTHDR]; /* extended local header */
int n, res;
crc = 0xffffffffL; /* initialize crc */
if (pkzip && !extended) { /* crc and length at the end otherwise */
orig_crc = LG(inbuf + LOCCRC);
orig_len = LG(inbuf + LOCLEN);
}
if (method != DEFLATED)
error("internal error, invalid method");
infl.gz_input = NextByte;
infl.gz_output = Flush;
infl.gz_slide = window;
res = inflate (&infl);
if (res == 3)
error("out of memory");
else if (res != 0)
error("invalid compressed format");
/* 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] = get_byte(); /* may cause an error if EOF */
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 */
orig_crc = LG(buf+4);
orig_len = LG(buf+12);
}
/* Validate decompression */
if (orig_crc != (crc ^ 0xffffffffL))
error("crc error");
if (orig_len != output_ptr)
error("length error");
/* Check if there are more entries in a pkzip file */
if (pkzip && inptr+4 < insize && LG(inbuf+inptr) == LOCSIG)
error("zip file has more than one entry");
}
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