Filter PHP's $_SERVER['PHP_SELF']

Question

I need to filter the unreliable $_SERVER['PHP_SELF'] varialbe. Is this a good approach:

function filterPhpSelf($str) 
{
    $phpself = basename(__FILE__);
    $str = substr($str, 0, strpos($str,$phpself)) . $phpself;
    return $unsafeStr;
}

where $str is $_SERVER['PHP_SELF']?

Answer 1

1) Your code will raise an error if run.

2) $_SERVER['PHP_SELF'] is not unsafe. Unsafe use of it is unsafe.

Answer 2

Yes, that will do. Though you will want to change:

return $unsafeStr;

to

return $str;