sigwaitinfo() and
sigwait() return the first pending signal from the set specified by
set. Should multiple signals from
set be pending, the lowest numbered one is returned. The selection order between realtime and non-realtime signals is unspecified. If there is no signal from
set pending at the time of the call, the calling thread is suspended until one of the specified signals is generated.
sigtimedwait() is exactly equal to
sigwaitinfo(), except
timeout specifies the maximum time interval for which the calling thread will be suspended. If
timeout is zero (tv_sec == tv_nsec == 0),
sigtimedwait() only checks the currently pending signals and returns immediately. If
NULL is used for
timeout,
sigtimedwait() behaves exactly like
sigwaitinfo() in all regards.
If several threads are waiting for a given signal, exactly one of them returns from the signal wait when the signal is generated.
Behaviour of these functions is unspecified if any of the signals in
set are unblocked at the time these functions are called.