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/*
File: file_mid.c
Copyright (C) 1998-2007 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.
*/
#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 "common.h"
#include "log.h"
static void register_header_check_mid(file_stat_t *file_stat);
const file_hint_t file_hint_mid= {
.extension="mid",
.description="MIDI Musical Instrument Digital Interface",
.max_filesize=50*1024*1024,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_mid
};
/* See http://www.sonicspot.com/guide/midifiles.html for more information about MIDI file format */
struct midi_header
{
char magic[4];
uint32_t len; /* = 6 */
uint16_t format;
uint16_t tracks;
int16_t time_division;
} __attribute__ ((gcc_struct, __packed__));
static void file_check_midi(file_recovery_t *file_recovery)
{
const uint64_t fs_org=file_recovery->file_size;
struct midi_header hdr;
unsigned int i;
unsigned int tracks;
uint64_t fs=4+4+6;
file_recovery->file_size=0;
if(my_fseek(file_recovery->handle, 0, SEEK_SET) < 0 ||
fread(&hdr, sizeof(hdr), 1, file_recovery->handle) != 1)
return ;
tracks=be16(hdr.tracks);
for(i=0; i<tracks; i++)
{
struct midi_header track;
#ifdef DEBUG_MIDI
log_info("file_check_midi 0x%08llx\n", (unsigned long long)fs);
#endif
if(my_fseek(file_recovery->handle, fs, SEEK_SET) < 0 ||
fread(&track, 8, 1, file_recovery->handle) != 1 ||
memcmp(&track.magic[0], "MTrk", 4)!=0)
return ;
fs+=(uint64_t)8+be32(track.len);
}
if(fs_org < fs)
return ;
file_recovery->file_size=fs;
}
static data_check_t data_check_midi(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
{
while(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size &&
file_recovery->calculated_file_size + 8 < file_recovery->file_size + buffer_size/2)
{
const unsigned int i=file_recovery->calculated_file_size - file_recovery->file_size + buffer_size/2;
const struct midi_header *hdr=(const struct midi_header*)&buffer[i];
const uint64_t len=be32(hdr->len);
#ifdef DEBUG_MIDI
log_info("data_check_midi 0x%08llx len=%llu\n", (long long unsigned)file_recovery->calculated_file_size, (long long unsigned)len);
#endif
if(memcmp(&hdr->magic[0], "MTrk", 4)!=0)
return DC_STOP;
file_recovery->calculated_file_size+=(uint64_t)8+len;
}
return DC_CONTINUE;
}
static int header_check_mid(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)
{
const struct midi_header *hdr=(const struct midi_header *)buffer;
if(be16(hdr->format) > 2 || be16(hdr->tracks) == 0)
return 0;
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_mid.extension;
file_recovery_new->file_check=&file_check_midi;
if(file_recovery_new->blocksize < 8)
return 1;
file_recovery_new->calculated_file_size=4+4+6;
file_recovery_new->data_check=&data_check_midi;
return 1;
}
static void register_header_check_mid(file_stat_t *file_stat)
{
static const unsigned char mid_header[8] = { 'M','T','h','d', 0, 0, 0, 0x6};
register_header_check(0, mid_header,sizeof(mid_header), &header_check_mid, file_stat);
}
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