This function seems to simply return the value of session.save_path from the [Session] section of php.ini. This has an important implication: the returned value can as well look like "0;0660;/var/lib/php/sessions", which is of course no valid path.
A way to extract the path despite the possible semicolons can be something like:
$ssp = explode(';', session_save_path());
echo end($ssp);
As end takes the array by reference, it's not possible to make a real one-liner without relying on an intermediate variable.
