sigwait(2) - NetBSD Manual Pages

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SIGTIMEDWAIT(2)           NetBSD System Calls Manual           SIGTIMEDWAIT(2)


NAME

     sigtimedwait, sigwaitinfo, sigwait -- wait for queued signals


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <signal.h>

     int
     sigtimedwait(const sigset_t * restrict set, siginfo_t * restrict info,
         const struct timespec * restrict timeout);

     int
     sigwaitinfo(const sigset_t * restrict set, siginfo_t * restrict info);

     int
     sigwait(const sigset_t * restrict set, int * restrict sig);


DESCRIPTION

     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
     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.


RETURN VALUES

     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.


ERRORS

     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-
                        fied 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 wait.


SEE ALSO

     sigaction(2), sigprocmask(2), signal(7)


STANDARDS

     The functions sigtimedwait(), sigwaitinfo(), and sigwait() conform to
     IEEE Std 1003.1-2001 (``POSIX.1'').


HISTORY

     The sigtimedwait(), sigwaitinfo(), and sigwait() functions appeared in
     NetBSD 2.0.

NetBSD 8.0                       April 2, 2012                      NetBSD 8.0