File

drupal-7.x/modules/system/system.tar.inc, line 1277

Class

Archive_Tar

Creates a (compressed) Tar archive *

Code

function _readHeader($v_binary_data, &$v_header) 
 {
  if (strlen($v_binary_data) == 0) {
    $v_header['filename'] = '';
    return true;
  }

  if (strlen($v_binary_data) != 512) {
    $v_header['filename'] = '';
    $this->_error('Invalid block size : ' . strlen($v_binary_data));
    return false;
  }

  if (!is_array($v_header)) {
    $v_header = array();
  }
  // ----- Calculate the checksum
  $v_checksum = 0;
  // ..... First part of the header
  for ($i = 0; $i < 148; $i++) {
    $v_checksum += ord(substr($v_binary_data, $i, 1));
  };
  // ..... Ignore the checksum value and replace it by ' ' (space)
  for ($i = 148; $i < 156; $i++) {
    $v_checksum += ord(' ');
  };
  // ..... Last part of the header
  for ($i = 156; $i < 512; $i++) {
    $v_checksum += ord(substr($v_binary_data, $i, 1));
  };

  $v_data = unpack("a100filename/a8mode/a8uid/a8gid/a12size/a12mtime/"
    . "a8checksum/a1typeflag/a100link/a6magic/a2version/"
    . "a32uname/a32gname/a8devmajor/a8devminor", 
  $v_binary_data);

  // ----- Extract the checksum
  $v_header['checksum'] = OctDec(trim($v_data['checksum']));
  if ($v_header['checksum'] != $v_checksum) {
    $v_header['filename'] = '';

    // ----- Look for last block (empty block)
    if (($v_checksum == 256) && ($v_header['checksum'] == 0)) {
      return true;
    }

    $this->_error('Invalid checksum for file "' . $v_data['filename']
      . '" : ' . $v_checksum . ' calculated, '
      . $v_header['checksum'] . ' expected');
    return false;
  }

  // ----- Extract the properties
  $v_header['filename'] = trim($v_data['filename']);
  if ($this->_maliciousFilename($v_header['filename'])) {
    $this->_error('Malicious .tar detected, file "' . $v_header['filename'] .
      '" will not install in desired directory tree');
    return false;
  }
  $v_header['mode'] = OctDec(trim($v_data['mode']));
  $v_header['uid'] = OctDec(trim($v_data['uid']));
  $v_header['gid'] = OctDec(trim($v_data['gid']));
  $v_header['size'] = OctDec(trim($v_data['size']));
  $v_header['mtime'] = OctDec(trim($v_data['mtime']));
  if (($v_header['typeflag'] = $v_data['typeflag']) == "5") {
    $v_header['size'] = 0;
  }
  $v_header['link'] = trim($v_data['link']);
  /* ----- All these fields are removed form the header because
		they do not carry interesting info
        $v_header[magic] = trim($v_data[magic]);
        $v_header[version] = trim($v_data[version]);
        $v_header[uname] = trim($v_data[uname]);
        $v_header[gname] = trim($v_data[gname]);
        $v_header[devmajor] = trim($v_data[devmajor]);
        $v_header[devminor] = trim($v_data[devminor]);
        */

  return true;
}