#!/usr/bin/php -q
<?PHP

  /**
   * Read all informations from FAT in image-file
   * 
   * ~#> php readinfo.php {path to image}
   * 
   * @author Bernd Holzmueller <bernd@tiggerswelt.net>
   * @license http://creativecommons.org/licenses/by-sa/3.0/de/ Creative Commons Attribution-Share Alike 3.0 Germany      
   * @copyright Copyright &copy; 2010 tiggersWelt.net
   **/
  
  if (!is_resource ($fat = @fopen ($argv [1], 'rb')))
    die ('Could not open FAT' . "\n");
  
  function freadint (&$f, $s, $p = 0, $t = true) {
    if (is_resource ($f)) {
      if ($p != 0)
        fseek ($f, $p, SEEK_SET);
      
      $v = fread ($f, $s);
      
      if (!$t)
        fseek ($f, $p, SEEK_SET);
    } else {
      $v = substr ($f, $p, $s);
      
      if ($t)
        $f = ($p > 0 ? substr ($f, 0, $p) : '') . substr ($f, $p + $s);
    }
    
    $r = 0;
    
    for ($i = $s - 1; $i >= 0; $i--)
      $r = ($r << 8) + ord ($v [$i]);
    
    return $r;
  }
  
  // Read the whole file-system-information
  $buf = fread ($fat, 0x200);
  
  // Read all informations
  $Opcode = freadint ($buf, 3);			// 0x00
  $OEMName = substr ($buf, 0, 8);		// 0x03
  $buf = substr ($buf, 8);
  
  $SectorSize = freadint ($buf, 2);		// 0x0B
  $ClusterSectors = freadint ($buf, 1);		// 0x0D
  $ReservedSectors = freadint ($buf, 2);	// 0x0E
  $FATCopies = freadint ($buf, 1);		// 0x10
  $RootEntryCount = freadint ($buf, 2);		// 0x11
  $Sectors = freadint ($buf, 2);		// 0x13
  $Media = freadint ($buf, 1);			// 0x15
  $FATSectors = freadint ($buf, 2);		// 0x16
  $TrackSectors = freadint ($buf, 2);		// 0x18
  $Pages = freadint ($buf, 2);			// 0x1A
  $HiddenSectors = freadint ($buf, 4);		// 0x1C
  $Sectors = freadint ($buf, 4);		// 0x20
  
  // Output FAT-Information
  echo
    'OEM-Name:              ' . $OEMName . "\n" .
    'Size of sector:        ' . $SectorSize . ' Bytes' . "\n" .
    'Sectors per Cluster:   ' . $ClusterSectors . ' Sectors' . "\n" .
    'Sectors per Track:     ' . $TrackSectors . ' Sectors' . "\n" .
    # 'Sectors per FAT:       ' . $FATSectors . ' Sectors' . "\n" .
    'Entries in Root:       ' . $RootEntryCount . ' Entries' . "\n" .
    'Reserved Sectors:      ' . $ReservedSectors . ' Sectors' . "\n" .
    'Hidden Sectors:        ' . $HiddenSectors . ' Sectors' . "\n" .
    'Maximum Sectors:       ' . $Sectors . ' Sectors' . "\n" .
    'FAT-Copies:            ' . $FATCopies . ' FATs' . "\n" .
    'Media-Byte:            0x' . dechex ($Media) . "\n" .
    'Pages:                 ' . $Pages . "\n";
  
  // Read advanced information - this differs between FAT12/16 and FAT32
  if (substr ($buf, 0x36 - 0x24, 3) == 'FAT') {
    $BIOSNumber = freadint ($buf, 1);
    freadint ($buf, 1); // Reserved byte
    $Signature = freadint ($buf, 1);
    $FSID = freadint ($buf, 4);
    $Name = substr ($buf, 0, 11);
    $Variant = substr ($buf, 11, 8);
    $Bootloader = substr ($buf, 19, 448);
    $buf = substr ($buf, 467);
    $BIOSBoot = freadint ($buf, 2);
    
    $Flags = 0;
    $Version = 0;
    $RootCluster = 0;
    $FSInfoSector = 0;
    $BootCopySector = 0;
  } elseif (substr ($buf, 0x52 - 0x24, 3) == 'FAT') {
    $FATSectors = freadint ($buf, 4);
    $Flags = freadint ($buf, 2);
    $Version = freadint ($buf, 2);
    $RootCluster = freadint ($buf, 4);
    $FSInfoSector = freadint ($buf, 2);
    $BootCopySector = freadint ($buf, 2);
    $buf = substr ($buf, 12); // Reserved bytes
    $BIOSNumber = freadint ($buf, 1);
    freadint ($buf, 1); // Reserved byte
    $Signature = freadint ($buf, 1);
    $FSID = freadint ($buf, 4);
    $Name = substr ($buf, 0, 11);
    $Variant = substr ($buf, 11, 8);
    $Bootloader = substr ($buf, 19, 420);
    $buf = substr ($buf, 439);
    $BIOSBoot = freadint ($buf, 2);
  } else
    die ('Unable to guess FAT-Format' . "\n");
  
  echo "\n" .
    'Sectors per FAT:       ' . $FATSectors . ' Sectors' . "\n" .
    'Flags:                 ' . $Flags . "\n" .
    'Version:               ' . $Version . "\n" .
    'Cluster with root:     ' . $RootCluster . "\n" .
    'FS Information sector: ' . $FSInfoSector . "\n" .
    'Sector with Boot-Copy: ' . $FSInfoSector . "\n" .
    'Physical drive:        0x' . dechex ($BIOSNumber) . "\n" .
    'Boot-Signature:        ' . $Signature . "\n" .
    'Filesystem-ID:         0x' . dechex ($FSID) . "\n" .
    'Name:                  ' . $Name . "\n" .
    'Variant:               ' . $Variant . "\n" .
    'BIOS-Signature:        0x' . dechex ($BIOSBoot) . "\n";

?>