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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¶
Thesigwait
() 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¶
Thesigwait
() 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¶
Thesigwait
() 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¶
Thesigwait
() function conforms to
ISO/IEC 9945-1:1996
(“POSIX.1”).September 6, 2013 | Debian |