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/*

    File: file_xz.c

    Copyright (C) 2012 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_xz)
#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"

/*@ requires \valid(file_stat); */
static void register_header_check_xz(file_stat_t *file_stat);

const file_hint_t file_hint_xz = {
  .extension = "xz",
  .description = "xz Archive",
  .max_filesize = PHOTOREC_MAX_FILE_SIZE,
  .recover = 1,
  .enable_by_default = 1,
  .register_header_check = &register_header_check_xz
};

/*@
  @ requires \valid(file_recovery);
  @ requires valid_file_recovery(file_recovery);
  @ requires \separated(file_recovery, file_recovery->handle, file_recovery->extension, &errno, &Frama_C_entropy_source);
  @ requires file_recovery->file_check == &file_check_xz;
  @ ensures \valid(file_recovery->handle);
  @ assigns *file_recovery->handle, errno, file_recovery->file_size;
  @ assigns Frama_C_entropy_source;
  @*/
static void file_check_xz(file_recovery_t *file_recovery)
{
  const unsigned char xz_footer[2] = { 'Y', 'Z' };
  file_search_footer(file_recovery, xz_footer, sizeof(xz_footer), 0);
}

/*@
  @ requires buffer_size > 0;
  @ requires \valid_read(buffer+(0..buffer_size-1));
  @ requires valid_file_recovery(file_recovery);
  @ requires \valid(file_recovery_new);
  @ requires file_recovery_new->blocksize > 0;
  @ requires separation: \separated(&file_hint_xz, buffer+(..), file_recovery, file_recovery_new);
  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
  @ assigns  *file_recovery_new;
  @*/
static int header_check_xz(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)
{
  reset_file_recovery(file_recovery_new);
  file_recovery_new->extension = file_hint_xz.extension;
  file_recovery_new->file_check = &file_check_xz;
  file_recovery_new->min_filesize = 9;
  return 1;
}

static void register_header_check_xz(file_stat_t *file_stat)
{
  /* https://tukaani.org/xz/xz-file-format.txt */
  /* HEADER_MAGIC + Stream Flag[0] */
  static const unsigned char xz_header[7] = {
    0xfd, '7', 'z', 'X', 'Z', 0x00, 0x00
  };
  register_header_check(0, xz_header, sizeof(xz_header), &header_check_xz, file_stat);
}
#endif