SIGSETMASK(3) | Library Functions Manual | SIGSETMASK(3) |
sigsetmask
— set
current signal mask
#include
<signal.h>
int
sigsetmask
(int
mask);
sigmask
(int
signum);
sigsetmask
()
sets the current signal mask. Signals are blocked from delivery if the
corresponding bit in mask is a 1; the macro
sigmask
()
is provided to construct the mask for a given
signum.
The system quietly disallows SIGKILL
or
SIGSTOP
to be blocked.
The previous set of masked signals is returned.
The following example utilizing
sigsetmask
():
int omask; omask = sigblock(sigmask(SIGINT) | sigmask(SIGHUP)); ... sigsetmask(omask & ~(sigmask(SIGINT) | sigmask(SIGHUP)));
Could be converted literally to:
sigset_t set, oset; sigemptyset(&set); sigaddset(&set, SIGINT); sigaddset(&set, SIGHUP); sigprocmask(SIG_BLOCK, &set, &oset); ... sigdelset(&oset, SIGINT); sigdelset(&oset, SIGHUP); sigprocmask(SIG_SETMASK, &oset, NULL);
Another, clearer, alternative is:
sigset_t set; sigemptyset(&set); sigaddset(&set, SIGINT); sigaddset(&set, SIGHUP); sigprocmask(SIG_BLOCK, &set, NULL); ... sigprocmask(SIG_UNBLOCK, &set, NULL);
To completely clear the signal mask using
sigsetmask
() one can do:
(void) sigsetmask(0);
Which can be expressed via sigprocmask(2) as:
sigset_t eset; sigemptyset(&eset); (void) sigprocmask(SIG_SETMASK, &eset, NULL);
kill(2), sigaction(2), sigprocmask(2), sigsuspend(2), sigblock(3), sigsetops(3), sigvec(3)
A sigsetmask
() system call first appeared
in 4.2BSD. In 4.3BSD-Reno,
it was reimplemented as a wrapper around
sigprocmask(2). The old
system call was kept for compatibility until OpenBSD
4.9.
July 17, 2013 | OpenBSD-6.1 |