Function auth_close 

pub unsafe extern "C" fn auth_close(_as: *mut auth_session_t) -> c_int

Terminates the BSD Authentication session

From auth_subr(3):

Also sets any environment variables requested by the login script (assuming the user was
not rejected) or removes files created b the login script if the authentication was not
successful. It returns the final state of the authentication request. A return value of 0
implies the user was not authenticated. A non-zero return value is made up of 1 or more of
the following values ORed together:

AUTH_OKAY       The user was authenticated.

AUTH_ROOTOKAY   The user was authenticated with a root instance.

AUTH_SECURE     The user was authenticated via a mechanism which is not subject to
                eavesdropping attacks (such as provided by token cards).