sigwait(3-thr)                                               sigwait(3-thr)

NAME
     sigwait - causes a thread to wait for an asynchronous signal

SYNOPSIS
     #include <pthread.h>

     int sigwait(sigsett *set);

PARAMETERS
     set       Set of pending signals upon which the calling thread will
               wait.

DESCRIPTION
     This routine causes a thread to wait for an asynchronous signal. It
     atomically chooses a pending signal from set, atomically clears it
     from the system's set of pending signals and returns that signal
     number. If no signal in set is pending at the time of the call, the
     thread is blocked until one or more signals becomes pending. The sig-
     nals defined by set may be unblocked during the call to this routine
     and will be blocked when the thread returns from the call unless some
     other thread is currently waiting for one of those signals.

     A thread must block the signals it waits for using sigprocmask() prior
     to calling this function.

     If more than one thread is using this routine to wait for the same
     signal, only one of these threads will return from this routine with
     the signal number.

     A call to sigwait() is a cancellation point.

RETURN VALUES
     Possible return values are as follows:

     EINVAL    One or more of the values specified by set is invalid.

     EINVAL    One or more of the values specified by set is not blocked.

     EINVAL    There are no values specified in set.

SEE ALSO
     pause(2), sigpending(2), sigprocmask(2), pthreadcancel(3-thr),
     pthreadsetasynccancel(3-thr), sigsetops(3C), signal(5).












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