    public function validate($string, $config, $context) {

        $string = trim($string);
        if ($string === '0') return $string;
        if ($string === '')  return false;
        $length = strlen($string);
        if (substr($string, $length - 2) == 'px') {
            $string = substr($string, 0, $length - 2);
        }
        if (!is_numeric($string)) return false;
        $int = (int) $string;

        if ($int < 0) return '0';

        // upper-bound value, extremely high values can
        // crash operating systems, see <http://ha.ckers.org/imagecrash.html>
        // WARNING, above link WILL crash you if you're using Windows

        if ($this->max !== null && $int > $this->max) return (string) $this->max;

        return (string) $int;

    }
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.