/*

    File: file_xar.c

    Copyright (C) 2015 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_xar)
#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"

/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_xar(file_stat_t *file_stat);

const file_hint_t file_hint_xar = {
  .extension = "xar",
  .description = "xar archive",
  .max_filesize = PHOTOREC_MAX_FILE_SIZE,
  .recover = 1,
  .enable_by_default = 1,
  .register_header_check = &register_header_check_xar
};

struct xar_header
{
  uint32_t magic;
  uint16_t size;
  uint16_t version;
  uint64_t toc_length_compressed;
  uint64_t toc_length_uncompressed;
  uint32_t cksum_alg;
  /* A nul-terminated, zero-padded to multiple of 4, message digest name
   * appears here if cksum_alg is 3 which must not be empty ("") or "none".
   */
};

/*@
  @ requires buffer_size >= sizeof(struct xar_header);
  @ requires separation: \separated(&file_hint_xar, 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);
  @ assigns  *file_recovery_new;
  @*/
static int header_check_xar(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 xar_header *hdr = (const struct xar_header *)buffer;
  const unsigned int cksum_alg = be32(hdr->cksum_alg);
  const unsigned int hdr_size = be16(hdr->size);
  const uint64_t size = be64(hdr->toc_length_compressed);
  if(be16(hdr->version) != 1)
    return 0;
  if(hdr_size < 28)
    return 0;
  if(cksum_alg == 3 && (hdr_size < 32 || hdr_size % 4 != 0))
    return 0;
  if(cksum_alg > 4)
    return 0;
  if(size >= PHOTOREC_MAX_FILE_SIZE)
    return 0;
  reset_file_recovery(file_recovery_new);
  file_recovery_new->extension = file_hint_xar.extension;
  file_recovery_new->min_filesize = (uint64_t)hdr_size + size;
  return 1;
}

static void register_header_check_xar(file_stat_t *file_stat)
{
  register_header_check(0, "xar!", 4, &header_check_xar, file_stat);
}
#endif