Function libsession_session_get_uid 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn libsession_session_get_uid(
    ctx: *mut libsession_context,
    session: *const c_char,
    ret_uid: *mut uid_t,
) -> LibsessionStatus

Safety

ctx and session must be valid, and ret_uid must point to writable storage.