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SIGTIMEDWAIT(2)               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
     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.

RETURN VALUES
     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 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
                        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 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 10.99                     April 2, 2012                    NetBSD 10.99