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SIGTIMEDWAIT(2) NetBSD System Calls Manual SIGTIMEDWAIT(2)
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by Kimmo Suominen.
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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 low-
est 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 speci-
fies the maximum time interval for which the calling thread will be sus-
pended. 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
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.
Upon successful completion of sigtimedwait() or sigwaitinfo() info is
updated with signal information, and the function returns the signal num-
ber. Otherwise, -1 is returned and the global variable errno indicates
the error. Upon successful completion of sigwait() sig is updated with
the 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 speci-
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 wait.
sigaction(2), sigprocmask(2), signal(7)
The functions sigtimedwait(), sigwaitinfo(), and sigwait() conform to
IEEE Std 1003.1-2001 (``POSIX.1'').
The sigtimedwait(), sigwaitinfo(), and sigwait() functions appeared in
NetBSD 9.3 April 2, 2012 NetBSD 9.3