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/*
File: file_bpg.c
Copyright (C) 1998-2007 Christophe GRENIER <grenier@cgsecurity.org>
Copyright (C) 2016 Dmitry Brant <me@dmitrybrant.com>
BPG specification can be found at:
https://bellard.org/bpg/bpg_spec.txt
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_bpg)
#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"
#define MAX_BPG_SIZE 0x800000
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_bpg(file_stat_t *file_stat);
const file_hint_t file_hint_bpg= {
.extension="bpg",
.description="Better Portable Graphics image",
.max_filesize=MAX_BPG_SIZE,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_bpg
};
/*@
@ requires buffer_size > 0;
@ requires \valid_read(buffer+(0..buffer_size-1));
@ requires \valid(buf_ptr);
@ requires \separated(buffer+(..), buf_ptr);
@ assigns *buf_ptr;
@*/
static unsigned int getue32(const unsigned char *buffer, const unsigned int buffer_size, unsigned int *buf_ptr)
{
uint64_t value = 0;
int bitsRead = 0;
/*@
@ loop invariant bitsRead <= 35;
@ loop invariant value < (bitsRead == 0 ? 1: (0x80 << (bitsRead-7)));
@ loop assigns value, bitsRead, *buf_ptr;
@ loop variant 35 - bitsRead;
@ */
while (*buf_ptr < buffer_size)
{
const unsigned int b = buffer[*buf_ptr];
*buf_ptr = *buf_ptr + 1;
value <<= 7;
value |= (b & 0x7F);
if ((b & 0x80) == 0)
break;
bitsRead += 7;
if (bitsRead >= 32)
break;
}
return value&0xffffffff;
}
/*@
@ requires buffer_size >= 6+3*5;
@ requires separation: \separated(&file_hint_bpg, 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);
@ ensures (\result == 1) ==> file_recovery_new->file_size == 0;
@ ensures (\result == 1) ==> (file_recovery_new->time == 0);
@ ensures (\result == 1) ==> (file_recovery_new->extension == file_hint_bpg.extension);
@ ensures (\result == 1) ==> (file_recovery_new->data_check== &data_check_size);
@ ensures (\result == 1) ==> (file_recovery_new->file_check == &file_check_size);
@ assigns *file_recovery_new;
@*/
static int header_check_bpg(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)
{
unsigned int buf_ptr = 6;
// get image width
const unsigned int picture_width = getue32(buffer, buffer_size, &buf_ptr);
// get image height
const unsigned int picture_height = getue32(buffer, buffer_size, &buf_ptr);
uint64_t size = getue32(buffer, buffer_size, &buf_ptr);
if(picture_width==0 || picture_height==0)
return 0;
if (size == 0) {
size = MAX_BPG_SIZE;
} else {
size += buf_ptr;
}
reset_file_recovery(file_recovery_new);
file_recovery_new->calculated_file_size=size;
file_recovery_new->data_check=&data_check_size;
file_recovery_new->file_check=&file_check_size;
file_recovery_new->extension=file_hint_bpg.extension;
return 1;
}
static void register_header_check_bpg(file_stat_t *file_stat)
{
static const unsigned char bpg_header[4]= {'B','P','G',0xFB};
register_header_check(0, bpg_header,sizeof(bpg_header), &header_check_bpg, file_stat);
}
#endif
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