/*

    File: file_ext2_sb.c

    Copyright (C) 1998-2005,2007 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.

 */

#if !defined(SINGLE_FORMAT) || defined(SINGLE_FORMAT_ext2_sb)
#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 "ext2_common.h"
#include "filegen.h"
#include "log.h"

/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_ext2_sb(file_stat_t *file_stat);

const file_hint_t file_hint_ext2_sb= {
  .extension="ext",
  .description="ext2/ext3/ext4 Superblock",
  .max_filesize=PHOTOREC_MAX_FILE_SIZE,
  .recover=0,
  .enable_by_default=1,
  .register_header_check=&register_header_check_ext2_sb
};

/*@
  @ requires file_recovery->file_rename==&file_rename_ext;
  @ requires valid_file_rename_param(file_recovery);
  @ ensures  valid_file_rename_result(file_recovery);
  @*/
static void file_rename_ext(file_recovery_t *file_recovery)
{
  unsigned char buffer[1024];
  char buffer_cluster[32];
  FILE *file;
  const struct ext2_super_block *sb=(const struct ext2_super_block *)&buffer;
  int buffer_size;
  unsigned long int block_nr;
  if((file=fopen(file_recovery->filename, "rb"))==NULL)
    return;
  buffer_size=fread(buffer, 1, sizeof(buffer), file);
  fclose(file);
  if(buffer_size!=sizeof(buffer))
    return;
  /*@ assert buffer_size == sizeof(buffer); */
#if defined(__FRAMAC__)
  Frama_C_make_unknown(buffer, sizeof(buffer));
#endif
  /*@ assert \initialized(buffer + (0 .. sizeof(buffer)-1)); */
  block_nr=(unsigned long int)le32(sb->s_first_data_block) + (unsigned long int)le16(sb->s_block_group_nr)*le32(sb->s_blocks_per_group);
  sprintf(buffer_cluster, "sb_%lu", block_nr);
#if defined(DISABLED_FOR_FRAMAC)
  buffer_cluster[sizeof(buffer_cluster)-1]='\0';
#endif
  file_rename(file_recovery, buffer_cluster, strlen(buffer_cluster), 0, NULL, 1);
}

/*@
  @ requires buffer_size >= sizeof(struct ext2_super_block);
  @ requires separation: \separated(&file_hint_ext2_sb, 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_ext2_sb(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 ext2_super_block *sb=(const struct ext2_super_block *)buffer;
  if(test_EXT2(sb, NULL)!=0)
    return 0;
  /*@ assert le32(sb->s_log_block_size) <= 6; */
  reset_file_recovery(file_recovery_new);
  file_recovery_new->extension=file_hint_ext2_sb.extension;
  file_recovery_new->file_size=(uint64_t)EXT2_MIN_BLOCK_SIZE<<le32(sb->s_log_block_size);
  file_recovery_new->data_check=&data_check_size;
  file_recovery_new->file_check=&file_check_size;
  file_recovery_new->file_rename=&file_rename_ext;
  return 1;
}

/*@
  @ requires file_recovery->data_check==&data_check_extdir;
  @ requires valid_data_check_param(buffer, buffer_size, file_recovery);
  @ ensures  valid_data_check_result(\result, file_recovery);
  @ assigns file_recovery->calculated_file_size;
  @*/
static data_check_t data_check_extdir(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
{
  /* Save only one block */
  file_recovery->calculated_file_size=buffer_size/2;
  return DC_STOP;
}

/*@
  @ requires valid_file_rename_param(file_recovery);
  @ ensures  valid_file_rename_result(file_recovery);
  @*/
static void file_rename_extdir(file_recovery_t *file_recovery)
{
  unsigned char buffer[512];
  char buffer_cluster[32];
  FILE *file;
  int buffer_size;
  const uint32_t *inode=(const uint32_t *)&buffer[0];
  if((file=fopen(file_recovery->filename, "rb"))==NULL)
    return;
  buffer_size=fread(buffer, 1, sizeof(buffer), file);
  fclose(file);
  if(buffer_size!=sizeof(buffer))
    return;
  /*@ assert buffer_size == sizeof(buffer); */
#if defined(__FRAMAC__)
  Frama_C_make_unknown(buffer, sizeof(buffer));
#endif
  /*@ assert \initialized(buffer + (0 .. sizeof(buffer)-1)); */
  sprintf(buffer_cluster, "inode_%u", (unsigned int)le32(*inode));
#if defined(DISABLED_FOR_FRAMAC)
  buffer_cluster[sizeof(buffer_cluster)-1]='\0';
#endif
  file_rename(file_recovery, buffer_cluster, strlen(buffer_cluster), 0, NULL, 1);
}

/*@
  @ requires buffer_size >= sizeof(struct ext2_super_block);
  @ requires separation: \separated(&file_hint_ext2_sb, 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_ext2_dir(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)
{
  static const unsigned char ext2_ll_dir2[6]= { 0x02, 0x02, '.',  '.', 0x00, 0x00};
  if(memcmp(&buffer[0x12], ext2_ll_dir2, sizeof(ext2_ll_dir2))!=0)
    return 0;
  reset_file_recovery(file_recovery_new);
  file_recovery_new->extension=file_hint_ext2_sb.extension;
  file_recovery_new->data_check=&data_check_extdir;
  file_recovery_new->file_check=&file_check_size;
  file_recovery_new->file_rename=&file_rename_extdir;
  /*@ assert valid_file_recovery(file_recovery_new); */
  return 1;
}

static void register_header_check_ext2_sb(file_stat_t *file_stat)
{
  static const unsigned char ext2_sb_header[2]= {0x53, 0xEF};
  static const unsigned char ext2_ll_dir1[8]= {0x0c, 0x00, 0x01, 0x02, '.', 0x00, 0x00, 0x00};
  register_header_check(0x38, ext2_sb_header, sizeof(ext2_sb_header), &header_check_ext2_sb, file_stat);
  register_header_check(0x4, ext2_ll_dir1, sizeof(ext2_ll_dir1), &header_check_ext2_dir, file_stat);
}
#endif