public/js/kcfinder/lib/helper_file.php
static function isWritable($filename) {
        $filename = path::normalize($filename);
        if (!is_file($filename) || (false === ($fp = @fopen($filename, 'a+'))))
            return false;
        fclose($fp);
        return true;
    }
static function isWritable($filename) {
        $filename = path::normalize($filename);
        if (!is_file($filename) || (false === ($fp = @fopen($filename, 'a+'))))
            return false;
        fclose($fp);
        return true;
    }
Checks if the given file is really writable. The standard PHP function
is_writable() does not work properly on Windows servers.
@param string $filename
@return bool