Added a GLIBC NOTES section describing sigisemptyset(),

sigandset(), and sigorset().

man3/sigsetops.3

@@ -21,8 +21,10 @@
 .\" 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()
 .\"
-.TH SIGSETOPS 3 1994-09-24 "Linux 1.0" "Linux Programmer's Manual"
+.TH SIGSETOPS 3 2005-11-17 "Linux 2.6.14" "Linux Programmer's Manual"
 
 .SH NAME
 sigemptyset, sigfillset, sigaddset, sigdelset, sigismember \- POSIX
@@ -30,7 +32,7 @@ signal set operations.
 
 .SH SYNOPSIS
 .B #include <signal.h>
-.sp 2
+.sp
 .BI "int sigemptyset(sigset_t *" set );
 .sp
 .BI "int sigfillset(sigset_t *" set );
@@ -92,6 +94,41 @@ is not a member, and \-1 on error.
 is not a valid signal.
 .SH "CONFORMING TO"
 POSIX
+.SH "GLIBC NOTES"
+If the _GNU_SOURCE feature test macro is defined, then <signal.h>
+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 non-standard (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),