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/*
File: file_tar.c
Copyright (C) 1998-2005,2007 Christophe GRENIER <grenier@cgsecurity.org>
This software 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 the Free Software Foundation, Inc., 51
Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#if !defined(SINGLE_FORMAT) || defined(SINGLE_FORMAT_tar)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include <ctype.h>
#include "types.h"
#include "filegen.h"
#include "file_tar.h"
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_tar(file_stat_t *file_stat);
static const unsigned char tar_header_gnu[6] = { 'u', 's', 't', 'a', 'r', 0x00 };
static const unsigned char tar_header_posix[8] = { 'u', 's', 't', 'a', 'r', ' ', ' ', 0x00 };
const file_hint_t file_hint_tar = {
.extension = "tar",
.description = "tar archive",
.max_filesize = PHOTOREC_MAX_FILE_SIZE,
.recover = 1,
.enable_by_default = 1,
.register_header_check = ®ister_header_check_tar
};
/*@
@ requires \valid_read(h);
@ terminates \true;
@ assigns \nothing;
@*/
static int is_valid_checksum_format(const struct tar_posix_header *h)
{
unsigned int i;
int space_allowed = 1;
int all_null = 1;
/* No checksum ? */
/*@
@ loop assigns i,all_null;
@ loop variant 8 - i;
@*/
for(i = 0; i < 8; i++)
if(h->chksum[i] != 0)
all_null = 0;
if(all_null != 0)
return 1;
/*
* Checksum should be stored as a six digit octal number with leading zeroes followed by a NUL and then a space.
* Various implementations do not adhere to this format, try to handle them
*/
/*@
@ loop assigns i,space_allowed;
@ loop variant 6 - i;
@*/
for(i = 0; i < 6; i++)
{
if(h->chksum[i] >= '0' || h->chksum[i] <= '7')
{
space_allowed = 0;
continue;
}
if(h->chksum[i] == ' ')
{
if(space_allowed == 0)
return 0;
}
else
return 0;
}
if(h->chksum[6] == 0 || h->chksum[7] == ' ')
return 1;
if((h->chksum[6] >= '0' || h->chksum[6] <= '7') && h->chksum[7] == ' ')
return 1;
return 0;
}
int is_valid_tar_header(const struct tar_posix_header *h)
{
/* Do not remove this check. */
if(memcmp(&h->magic, tar_header_gnu, sizeof(tar_header_gnu)) != 0 && memcmp(&h->magic, tar_header_posix, sizeof(tar_header_posix)) != 0)
return 0;
if(is_valid_checksum_format(h) == 0)
return 0;
return 1;
}
/*@
@ requires buffer_size >= sizeof(struct tar_posix_header);
@ requires separation: \separated(&file_hint_tar, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_tar(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
/*@ assert valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new); */
const struct tar_posix_header *h = (const struct tar_posix_header *)buffer;
if(is_valid_tar_header(h) == 0)
return 0;
/*@ assert \valid_read(file_recovery); */
if(file_recovery->file_stat != NULL && file_recovery->file_stat->file_hint == &file_hint_tar)
{
/* header_ignored(file_recovery_new); is useless as there is no file check */
return 0;
}
reset_file_recovery(file_recovery_new);
file_recovery_new->extension = file_hint_tar.extension;
file_recovery_new->min_filesize = 512;
/*@ assert valid_file_recovery(file_recovery_new); */
return 1;
}
/*@
@ requires valid_register_header_check(file_stat);
@*/
static void register_header_check_tar(file_stat_t *file_stat)
{
register_header_check(0x101, tar_header_gnu, sizeof(tar_header_gnu), &header_check_tar, file_stat);
#ifndef DISABLED_FOR_FRAMAC
register_header_check(0x101, tar_header_posix, sizeof(tar_header_posix), &header_check_tar, file_stat);
#endif
}
#endif
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