busybox/archival/libunarchive/check_trailer_gzip.c

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2002-09-25 08:17:48 +05:30
/* vi: set sw=4 ts=4: */
/*
* busybox gunzip trailing header handler
* Copyright Glenn McGrath 2002
*
* 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.
*/
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "config.h"
#include "busybox.h"
#include "unarchive.h"
extern unsigned int gunzip_crc;
extern unsigned int gunzip_bytes_out;
extern unsigned char *bytebuffer;
extern unsigned short bytebuffer_offset;
extern unsigned short bytebuffer_size;
//extern unsigned char *gunzip_in_buffer;
//extern unsigned char gunzip_in_buffer_count;
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extern void check_trailer_gzip(int src_fd)
{
unsigned int stored_crc = 0;
unsigned char count;
/* top up the input buffer with the rest of the trailer */
count = bytebuffer_size - bytebuffer_offset;
if (count < 8) {
xread_all(src_fd, &bytebuffer[bytebuffer_size], 8 - count);
bytebuffer_size += 8 - count;
}
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for (count = 0; count != 4; count++) {
stored_crc |= (bytebuffer[bytebuffer_offset] << (count * 8));
bytebuffer_offset++;
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}
/* Validate decompression - crc */
if (stored_crc != (gunzip_crc ^ 0xffffffffL)) {
error_msg_and_die("crc error");
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}
/* Validate decompression - size */
if (gunzip_bytes_out !=
(bytebuffer[bytebuffer_offset] | (bytebuffer[bytebuffer_offset+1] << 8) |
(bytebuffer[bytebuffer_offset+2] << 16) | (bytebuffer[bytebuffer_offset+3] << 24))) {
error_msg_and_die("Incorrect length, but crc is correct");
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}
}