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/*
File: file_ttf.c
Copyright (C) 2009 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_ttf)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include "types.h"
#include "common.h"
#include "filegen.h"
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_ttf(file_stat_t *file_stat);
const file_hint_t file_hint_ttf= {
.extension="ttf",
.description="TrueType Font",
.max_filesize=PHOTOREC_MAX_FILE_SIZE,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_ttf
};
/*
* https://docs.microsoft.com/en-us/typography/opentype/spec/otff
*/
struct ttf_offset_table
{
int32_t sfnt_version;
uint16_t numTables;
uint16_t searchRange;
uint16_t entrySelector;
uint16_t rangeShift;
};
struct ttf_table_directory
{
uint32_t tag;
uint32_t checkSum;
uint32_t offset; /* Offset from beginning of TrueType font file. */
uint32_t length; /* Length of this table. */
};
/*@
@ terminates \true;
@ assigns \nothing;
@*/
static unsigned int td_ilog2(unsigned int v)
{
unsigned int l = 0;
/*@
@ loop assigns v,l;
@ loop unroll 16;
@ loop variant v;
@*/
while(v >>= 1)
l++;
return l;
}
/*@
@ requires buffer_size >= sizeof(struct ttf_offset_table);
@ requires separation: \separated(&file_hint_ttf, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ terminates \true;
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_ttf(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 ttf_offset_table *ttf=(const struct ttf_offset_table *)buffer;
const unsigned int numTables=be16(ttf->numTables);
const unsigned int entrySelector=be16(ttf->entrySelector);
const unsigned int searchRange=be16(ttf->searchRange);
const unsigned int rangeShift=be16(ttf->rangeShift);
if(numTables == 0)
return 0;
/* searchRange (Maximum power of 2 <= numTables) x 16.
* entrySelector Log2(maximum power of 2 <= numTables).
* rangeShift NumTables x 16-searchRange.
* */
if(td_ilog2(numTables) != entrySelector)
return 0;
if((16<<entrySelector) != searchRange)
return 0;
if(numTables * 16 != rangeShift+searchRange)
return 0;
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_ttf.extension;
if(sizeof(struct ttf_offset_table) + numTables * sizeof(struct ttf_table_directory)
<= buffer_size)
{
/*@ assert sizeof(struct ttf_offset_table) + numTables * sizeof(struct ttf_table_directory) <= buffer_size; */
/*@ assert numTables * sizeof(struct ttf_table_directory) <= buffer_size - sizeof(struct ttf_offset_table); */
/*@ assert numTables <= (buffer_size - sizeof(struct ttf_offset_table)) / sizeof(struct ttf_table_directory); */
/*@ assert \valid_read(buffer + (0 .. buffer_size - 1)); */
/*@ assert \valid_read(buffer + (0 .. sizeof(struct ttf_offset_table) + numTables * sizeof(struct ttf_table_directory) - 1)); */
uint64_t max_offset=0;
unsigned int i;
const struct ttf_table_directory*ttf_dir=(const struct ttf_table_directory*)&buffer[sizeof(struct ttf_offset_table)];
/*@ assert \valid_read(ttf_dir + (0 .. numTables -1)); */
/*@
@ loop assigns i, max_offset;
@ loop variant numTables - i;
@*/
for(i=0; i<numTables; i++)
{
/*@ assert 0 <= i < numTables; */
/*@ assert \valid_read(&ttf_dir[i]); */
/* Do not align the end of the table with "|0x3;"*/
const uint64_t new_offset=((uint64_t)be32(ttf_dir[i].offset) + be32(ttf_dir[i].length));
if(max_offset < new_offset)
max_offset=new_offset;
}
file_recovery_new->calculated_file_size=max_offset;
file_recovery_new->data_check=&data_check_size;
file_recovery_new->file_check=&file_check_size;
}
return 1;
}
static void register_header_check_ttf(file_stat_t *file_stat)
{
static const unsigned char header_ttf[5]= {0x00 , 0x01, 0x00, 0x00, 0x00};
register_header_check(0, header_ttf, sizeof(header_ttf), &header_check_ttf, file_stat);
}
#endif
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