SIGTIMEDWAIT(2) BSD System Calls Manual SIGTIMEDWAIT(2)
sigtimedwait, sigwaitinfo, sigwait -- wait for queued signals
Standard C Library (libc, -lc)
sigtimedwait(const sigset_t * restrict set, siginfo_t * restrict info,
const struct timespec * restrict timeout);
sigwaitinfo(const sigset_t * restrict set, siginfo_t * restrict info);
sigwait(const sigset_t * restrict set, int * restrict sig);
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 immedi-
ately. If NULL is used for timeout, sigtimedwait() behaves exactly like sigwaitinfo() in
If several threads are waiting for a given signal, exactly one of them returns from the sig-
nal 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.
Upon successful completion of sigtimedwait() or sigwaitinfo() info is updated with signal
information, and the function returns the signal number. Otherwise, -1 is returned and the
global variable errno indicates the error. Upon successful completion of sigwait() sig is
updated with ihe signal number, and the function returns 0. Otherwise, a non-zero error
code is returned,
sigwaitinfo() and sigwait() always succeed.
sigtimedwait() will fail and the info pointer will remain unchanged if:
[EAGAIN] No signal specified in set was generated in the specified timeout.
sigtimedwait() may also fail if:
[EINVAL] The specified timeout was invalid.
This error is only checked if no signal from set is pending and it would be necessary to
sigaction(2), sigprocmask(2), signal(7)
The functions sigtimedwait(), sigwaitinfo(), and sigwait() conform to IEEE Std 1003.1-2001
The sigtimedwait(), sigwaitinfo(), and sigwait() functions appeared in NetBSD 2.0.
BSD May 30, 2010 BSD