function get_is_file($dir, $item)
{
    $filename = get_abs_item($dir, $item);
	return @is_file($filename);
}
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.