rt_sigpending allows pending signals that have been raised while blocked to be examined. The set value stores the signal mask of the pending signals. sigsetesize should indicate the size of a sigset_t type or larger; otherwise, an error is returned.
rt_sigpending returns 0 on success. Otherwise, rt_sigpending returns one of the errors listed in the "Errors" section.
rt_sigaction(2), rt_sigprocmask(2), rt_sigqueueinfo(2), rt_sigreturn(2), rt_sigsuspend(2), rt_sigtimedwait(2)