CTar::getDataSize

function getDataSize($file)
{
	$size = &$this->dataSizeCache[$file];
	if (!$size)
	{
		if (!file_exists($file))
			$size = false;
		else
		{
			if (preg_match('#.gz(.[0-9]+)?$#',$file))
			{
				$f = fopen($file, "rb");
				fseek($f, 16);
				if (fread($f, 2) == 'BX')
					$size = end(unpack("V", fread($f, 4)));
				else
				{
//						$this->Error('Wrong GZIP Extra Field');
					$size = false;
				}
				fclose($f);
			}
			else
				$size = filesize($file);
		}
	}

	return $size;
}