SIGSUSPEND(2)             FreeBSD System Calls Manual            SIGSUSPEND(2)

NAME
     sigsuspend - atomically release blocked signals and wait for interrupt

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <signal.h>

     int
     sigsuspend(const sigset_t *sigmask);

DESCRIPTION
     The sigsuspend() system call temporarily changes the blocked signal mask
     to the set to which sigmask points, and then waits for a signal to
     arrive; on return the previous set of masked signals is restored.  The
     signal mask set is usually empty to indicate that all signals are to be
     unblocked for the duration of the call.

     In normal usage, a signal is blocked using sigprocmask(2) to begin a
     critical section, variables modified on the occurrence of the signal are
     examined to determine that there is no work to be done, and the process
     pauses awaiting work by using sigsuspend() with the previous mask
     returned by sigprocmask(2).

RETURN VALUES
     The sigsuspend() system call always terminates by being interrupted,
     returning -1 with errno set to EINTR.

SEE ALSO
     pselect(2), sigaction(2), sigpending(2), sigprocmask(2), sigtimedwait(2),
     sigwait(2), sigwaitinfo(2), sigsetops(3)

STANDARDS
     The sigsuspend() system call is expected to conform to IEEE Std
     1003.1-1990 ("POSIX.1").

FreeBSD 13.1-RELEASE-p6         August 16, 2013        FreeBSD 13.1-RELEASE-p6