Language: PHP
Label: safe
CWE: CWE-79 \u2014 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product 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.

Code:
    public static function singleton()
    {
        if (empty(FSTools::$singleton)) FSTools::$singleton = new FSTools();
        return FSTools::$singleton;
    }