GUMP::validate_extension PHP Method

    protected function validate_extension($field, $input, $param = null)
    {
        if ($input[$field]['error'] !== 4) {
            $param = trim(strtolower($param));
            $allowed_extensions = explode(';', $param);
            $path_info = pathinfo($input[$field]['name']);
            $extension = $path_info['extension'];
            if (in_array($extension, $allowed_extensions)) {
                return;
            }
            return array('field' => $field, 'value' => $input[$field], 'rule' => __FUNCTION__, 'param' => $param);
        }
    }