sigwait(2) [freebsd man page]

SIGWAIT(2)						      BSD System Calls Manual							SIGWAIT(2)

NAME

     sigwait -- select a set of signals

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <signal.h>

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

DESCRIPTION

     The sigwait() system call selects a set of signals, specified by set.  If none of the selected signals are pending, sigwait() waits until one
     or more of the selected signals has been generated.  Then sigwait() atomically clears one of the selected signals from the set of pending
     signals (for the process or for the current thread) and sets the location pointed to by sig to the signal number that was cleared.

     The signals specified by set should be blocked at the time of the call to sigwait().

     If more than one thread is using sigwait() to wait for the same signal, no more than one of these threads will return from sigwait() with the
     signal number.  If more than a single thread is blocked in sigwait() for a signal when that signal is generated for the process, it is
     unspecified which of the waiting threads returns from sigwait().  If the signal is generated for a specific thread, as by pthread_kill(),
     only that thread will return.

     Should any of the multiple pending signals in the range SIGRTMIN to SIGRTMAX be selected, it will be the lowest numbered one.  The selection
     order between realtime and non-realtime signals, or between multiple pending non-realtime signals, is unspecified.

IMPLEMENTATION NOTES

     The sigwait() function is implemented as a wrapper around the __sys_sigwait() system call, which retries the call on EINTR error.

RETURN VALUES

     If successful, sigwait() returns 0 and sets the location pointed to by sig to the cleared signal number.  Otherwise, an error number is
     returned.

ERRORS

     The sigwait() system call will fail if:

     [EINVAL]		The set argument specifies one or more invalid signal numbers.

SEE ALSO

     sigaction(2), sigpending(2), sigqueue(2), sigsuspend(2), sigtimedwait(2), sigwaitinfo(2), pause(3), pthread_sigmask(3)

STANDARDS

     The sigwait() function conforms to ISO/IEC 9945-1:1996 (``POSIX.1'').

BSD
								 September 6, 2013							       BSD

SIGTIMEDWAIT(2) 					      BSD 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 ihe 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.

BSD
								   May 30, 2010 							       BSD