sigwait(2) [debian 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 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.

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.

     [EFAULT]		Any arguments point outside the allocated address space or there is a memory protection fault.

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
								 November 11, 2005							       BSD

SIGTIMEDWAIT(2) 					      BSD System Calls Manual						   SIGTIMEDWAIT(2)

NAME

     sigtimedwait, sigwaitinfo -- wait for queued signals (REALTIME)

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);

DESCRIPTION

     The sigtimedwait() system call is equivalent to sigwaitinfo() except that if none of the signals specified by set are pending, sigtimedwait()
     waits for the time interval specified in the timespec structure referenced by timeout.  If the timespec structure pointed to by timeout is
     zero-valued and if none of the signals specified by set are pending, then sigtimedwait() returns immediately with an error.  If timeout is
     the NULL pointer, the behavior is unspecified.  CLOCK_MONOTONIC clock is used to measure the time interval specified by the timeout argument.

     The sigwaitinfo() system call selects the pending signal from the set specified by set.  Should any of multiple pending signals in the range
     SIGRTMIN to SIGRTMAX be selected, it shall be the lowest numbered one.  The selection order between realtime and non-realtime signals, or
     between multiple pending non-realtime signals, is unspecified.  If no signal in set is pending at the time of the call, the calling thread is
     suspended until one or more signals in set become pending or until it is interrupted by an unblocked, caught signal.

     The sigwaitinfo() system call is equivalent to the sigwait() system call if the info argument is NULL.  If the info argument is non-NULL, the
     sigwaitinfo() function is equivalent to sigwait(), except that the selected signal number shall be stored in the si_signo member, and the
     cause of the signal shall be stored in the si_code member.  Besides this, the sigwaitinfo() and sigtimedwait() system calls may return EINTR
     if interrupted by signal, which is not allowed for the sigwait() function.

     If any value is queued to the selected signal, the first such queued value is dequeued and, if the info argument is non-NULL, the value is
     stored in the si_value member of info.  The system resource used to queue the signal is released and returned to the system for other use.
     If no value is queued, the content of the si_value member is zero-valued.	If no further signals are queued for the selected signal, the
     pending indication for that signal is reset.

RETURN VALUES

     Upon successful completion (that is, one of the signals specified by set is pending or is generated) sigwaitinfo() and sigtimedwait() return
     the selected signal number.  Otherwise, the functions return a value of -1 and set the global variable errno to indicate the error.

ERRORS

     The sigtimedwait() system call will fail if:

     [EAGAIN]		No signal specified by set was generated within the specified timeout period.

     The sigtimedwait() and sigwaitinfo() system calls fail if:

     [EINTR]		The wait was interrupted by an unblocked, caught signal.

     The sigtimedwait() system call may also fail if:

     [EINVAL]		The timeout argument specified a tv_nsec value less than zero or greater than or equal to 1000 million.  Kernel only
			checks for this error if no signal is pending in set and it is necessary to wait.

SEE ALSO

     sigaction(2), sigpending(2), sigqueue(2), sigsuspend(2), sigwait(2), pause(3), pthread_sigmask(3), siginfo(3)

STANDARDS

     The sigtimedwait() and sigwaitinfo() system calls conform to ISO/IEC 9945-1:1996 (``POSIX.1'').

BSD
								September 27, 2012							       BSD