public static function owner(String $file)
    {
        $file = self::rpath($file);

        if( ! file_exists($file) )
        {
            throw new Exception\FileNotFoundException(NULL, $file);
        }

        $owner = fileowner($file);

        if( function_exists('posix_getpwuid') )
        {
            return posix_getpwuid($owner);
        }
        else
        {
            return $owner;
        }
    }