	protected function readlink($path) {
		if (!($target = @readlink($path))) {
			return null;
		}

		if (strpos($target, $this->systemRoot) !== 0) {
			$target = $this->_joinPath(dirname($path), $target);
		}

		if (!file_exists($target)) {
			return false;
		}
		
		return $target;
	}
The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.