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.\"	$OpenBSD: sigsetmask.3,v 1.15 2013/07/17 05:42:10 schwarze Exp $
.\"
.Dd $Mdocdate: July 17 2013 $
.Dt SIGSETMASK 3
.Os
.Sh NAME
.Nm sigsetmask
.Nd set current signal mask
.Sh SYNOPSIS
.In signal.h
.Ft int
.Fn sigsetmask "int mask"
.Fn sigmask "int signum"
.Sh DESCRIPTION
.Bf -symbolic
This interface is made obsoleted by:
.Ef
.Xr sigprocmask 2 .
.Pp
.Fn sigsetmask
sets the current signal mask.
Signals are blocked from delivery if the
corresponding bit in
.Fa mask
is a 1; the macro
.Fn sigmask
is provided to construct the mask for a given
.Fa signum .
.Pp
The system
quietly disallows
.Dv SIGKILL
or
.Dv SIGSTOP
to be blocked.
.Sh RETURN VALUES
The previous set of masked signals is returned.
.Sh EXAMPLES
The following example utilizing
.Fn sigsetmask :
.Bd -literal -offset indent
int omask;

omask = sigblock(sigmask(SIGINT) | sigmask(SIGHUP));

\&...

sigsetmask(omask & ~(sigmask(SIGINT) | sigmask(SIGHUP)));
.Ed
.Pp
Could be converted literally to:
.Bd -literal -offset indent
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);
.Ed
.Pp
Another, clearer, alternative is:
.Bd -literal -offset indent
sigset_t set;

sigemptyset(&set);
sigaddset(&set, SIGINT);
sigaddset(&set, SIGHUP);
sigprocmask(SIG_BLOCK, &set, NULL);

\&...

sigprocmask(SIG_UNBLOCK, &set, NULL);
.Ed
.Pp
To completely clear the signal mask using
.Fn sigsetmask
one can do:
.Bd -literal -offset indent
(void) sigsetmask(0);
.Ed
.Pp
Which can be expressed via
.Xr sigprocmask 2
as:
.Bd -literal -offset indent
sigset_t eset;

sigemptyset(&eset);
(void) sigprocmask(SIG_SETMASK, &eset, NULL);
.Ed
.Sh SEE ALSO
.Xr kill 2 ,
.Xr sigaction 2 ,
.Xr sigprocmask 2 ,
.Xr sigsuspend 2 ,
.Xr sigblock 3 ,
.Xr sigsetops 3 ,
.Xr sigvec 3
.Sh HISTORY
A
.Fn sigsetmask
system call first appeared in
.Bx 4.2 .
In
.Bx 4.3 Reno ,
it was reimplemented as a wrapper around
.Xr sigprocmask 2 .
The old system call was kept for compatibility until
.Ox 4.9 .