man3/sigsetops.3

.\" Copyright (c) 1994 Mike Battersby
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" 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)