.\" Copyright (c) 1994 Mike Battersby
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified by aeb, 960721
.\" 2005-11-21, mtk, added descriptions of sigisemptyset(), sigandset(),
.\"                  and sigorset()
.\" 2007-10-26 mdw   added wording that a sigset_t must be initialized
.\"                  prior to use
.\"
.TH SIGSETOPS 3 2008-09-01 "Linux" "Linux Programmer's Manual"
.SH NAME
sigemptyset, sigfillset, sigaddset, sigdelset, sigismember \- POSIX
signal set operations.
.SH SYNOPSIS
.B #include <signal.h>
.sp
.BI "int sigemptyset(sigset_t *" set );
.sp
.BI "int sigfillset(sigset_t *" set );
.sp
.BI "int sigaddset(sigset_t *" set ", int " signum );
.sp
.BI "int sigdelset(sigset_t *" set ", int " signum );
.sp
.BI "int sigismember(const sigset_t *" set ", int " signum );
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR sigemptyset (),
.BR sigfillset (),
.BR sigaddset (),
.BR sigdelset (),
.BR sigismember ():
.RS 4
_POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_SOURCE
.RE
.ad b
.SH DESCRIPTION
These functions allow the manipulation of POSIX signal sets.
.PP
.BR sigemptyset ()
initializes the signal set given by
.I set
to empty, with all signals excluded from the set.
.PP
.BR sigfillset ()
initializes
.I set
to full, including all signals.
.PP
.BR sigaddset ()
and
.BR sigdelset ()
add and delete respectively signal
.I signum
from
.IR set .
.PP
.BR sigismember ()
tests whether
.I signum
is a member of
.IR set .
.PP
Objects of type
.I sigset_t
must be initialized by a call to either
.BR sigemptyset ()
or
.BR sigfillset ()
before being passed to the functions
.BR sigaddset (),
.BR sigdelset ()
and
.BR sigismember ()
or the additional glibc functions described below
.RB ( sigisemptyset (),
.BR sigandset (),
and
.BR sigorset ()).
The results are undefined if this is not done.
.SH RETURN VALUE
.BR sigemptyset (),
.BR sigfillset (),
.BR sigaddset (),
and
.BR sigdelset ()
return 0 on success and \-1 on error.
.PP
.BR sigismember ()
returns 1 if
.I signum
is a member of
.IR set ,
0 if
.I signum
is not a member, and \-1 on error.
.SH ERRORS
.TP
.B EINVAL
.I sig
is not a valid signal.
.SH CONFORMING TO
POSIX.1-2001.
.SH NOTES
.SS Glibc notes
If the
.B _GNU_SOURCE
feature test macro is defined, then \fI<signal.h>\fP
exposes three other functions for manipulating signal
sets.
.TP
.BI "int sigisemptyset(sigset_t *" set );
returns 1 if
.I set
contains no signals, and 0 otherwise.
.TP
.BI "int sigorset(sigset_t *" dest ", sigset_t *" left \
", sigset_t *" right );
places the union of the sets
.I left
and
.I right
in
.IR dest .
.TP
.BI "int sigandset(sigset_t *" dest ", sigset_t *" left \
", sigset_t *" right );
places the intersection of the sets
.I left
and
.I right
in
.IR dest .
.PP
.BR sigorset ()
and
.BR sigandset ()
return 0 on success, and \-1 on failure.
.PP
These functions are nonstandard (a few other systems provide similar
functions) and their use should be avoided in portable applications.
.SH SEE ALSO
.BR sigaction (2),
.BR sigpending (2),
.BR sigprocmask (2),
.BR sigsuspend (2)