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SIGWAIT(2) 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 loca- tion 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 un- specified 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 selec- tion order between realtime and non-realtime signals, or between multi- ple 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 re- turned. ERRORS The sigwait() system call will fail if: [EINVAL] The set argument specifies one or more invalid sig- nal 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"). FreeBSD 13.2 September 6, 2013 SIGWAIT(2)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS
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