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/*
File: file_ogg.c
Copyright (C) 1998-2005,2007-2008 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_ogg)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include "types.h"
#include "filegen.h"
#include "log.h"
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_ogg(file_stat_t *file_stat);
const file_hint_t file_hint_ogg= {
.extension="ogg",
.description="OGG audio",
.max_filesize=PHOTOREC_MAX_FILE_SIZE,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_ogg
};
/* header=OggS, version=0 */
static const unsigned char ogg_header[5]= {'O','g','g','S', 0x00};
/* http://www.ietf.org/rfc/rfc3533.txt */
/*@
@ requires file_recovery->data_check==&data_check_ogg;
@ requires valid_data_check_param(buffer, buffer_size, file_recovery);
@ ensures valid_data_check_result(\result, file_recovery);
@ assigns file_recovery->calculated_file_size;
@*/
static data_check_t data_check_ogg(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
{
/*@ assert file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE; */
/*@ assert file_recovery->file_size <= PHOTOREC_MAX_FILE_SIZE; */
/*@
@ loop assigns file_recovery->calculated_file_size;
@ loop variant file_recovery->file_size + buffer_size/2 - (file_recovery->calculated_file_size + 27 +255);
@*/
while(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size &&
file_recovery->calculated_file_size + 27 +255 < file_recovery->file_size + buffer_size/2)
{
const unsigned int i=file_recovery->calculated_file_size + buffer_size/2 - file_recovery->file_size;
/*@ assert 0 <= i < buffer_size - (27 + 255); */
if(memcmp(&buffer[i],ogg_header,sizeof(ogg_header))==0)
{
const unsigned int number_page_segments=buffer[i+26];
const unsigned int header_size = number_page_segments + 27;
unsigned int page_size;
unsigned int j;
page_size=header_size;
/*@
@ loop invariant page_size <= 255 + 27 + j * 255;
@ loop assigns j, page_size;
@ loop variant number_page_segments - j;
@ */
for(j=0; j<number_page_segments; j++)
page_size+=buffer[i+27+j];
if(page_size<27)
{
return DC_STOP;
}
/* By definition, page_size<=27+255+255*255=65307 */
file_recovery->calculated_file_size+=page_size;
/*
log_debug("+0x%x=0x%x\n",page_size,file_recovery->calculated_file_size);
*/
}
else
{
return DC_STOP;
}
}
return DC_CONTINUE;
}
/*@
@ requires buffer_size >= 0x78+7;
@ requires separation: \separated(&file_hint_ogg, 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);
@*/
static int header_check_ogg(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)
{
static const unsigned char sign_theora[7]= {0x80, 't', 'h', 'e', 'o', 'r', 'a'};
/* http://en.wikipedia.org/wiki/Ogg#File_format */
/* Return if not Beginning Of Stream and already saving the file */
if((buffer[5]&0x02)!=0x02 &&
file_recovery->file_stat!=NULL &&
file_recovery->file_check!=NULL &&
file_recovery->file_stat->file_hint==&file_hint_ogg)
{
header_ignored(file_recovery_new);
return 0;
}
reset_file_recovery(file_recovery_new);
file_recovery_new->calculated_file_size=0;
if(file_recovery_new->blocksize > 27+255)
{
file_recovery_new->data_check=&data_check_ogg;
file_recovery_new->file_check=&file_check_size;
}
/* Ogg data, Theora video */
if(memcmp(&buffer[28], sign_theora, sizeof(sign_theora))==0)
file_recovery_new->extension="ogv";
else if(memcmp(&buffer[0x78], sign_theora, sizeof(sign_theora))==0)
file_recovery_new->extension="ogv";
else
file_recovery_new->extension=file_hint_ogg.extension;
return 1;
}
static void register_header_check_ogg(file_stat_t *file_stat)
{
register_header_check(0, ogg_header,sizeof(ogg_header), &header_check_ogg, file_stat);
}
#endif
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