SIGSETOPS(3)							  SIGSETOPS(3)

NAME    [Toc]    [Back]

     sigsetops:	sigaddset, sigdelset, sigemptyset, sigfillset, sigismember,
     sgi_altersigs, sgi_sigffset, sgi_siganyset, sgi_dumpset - signal set
     manipulation and examination routines (POSIX, with	SGI-specific
     additions)

SYNOPSIS    [Toc]    [Back]

   POSIX
     #include <signal.h>

     int sigaddset(sigset_t *set, int sig);

     int sigdelset(sigset_t *set, int sig);

     int sigemptyset(sigset_t *set);

     int sigfillset(sigset_t *set);

     int sigismember(sigset_t *set, int	sig);

   SGI
     int sgi_altersigs(int action, sigset_t *set, int sigarray[]);

     int sgi_sigffset(sigset_t *set, int clearit);

     int sgi_siganyset(sigset_t	*set);

     int sgi_dumpset(sigset_t *set);

DESCRIPTION    [Toc]    [Back]

     These library calls modify	or return information about the	disposition of
     the signal	mask pointed to	by set.	The system defines a set of signals
     that may be delivered to a	process.  Signal delivery resembles the
     occurrence	of a hardware interrupt:  the signal is	blocked	from further
     occurrence, the current process context is	saved, and a new one is	built.
     A global signal mask defines the set of signals currently blocked from
     delivery to a process; it may be changed with a sigprocmask(2) call.  The
     masks submitted as	parameters to sigprocmask, sigaction, and sigsuspend
     and returned by sigpending	may be constructed, altered, and examined via
     the sigsetops described in	this man page.	They do	NOT themselves alter
     the global	signal mask.  The masks	that the routines manipulate are of
     type sigset_t.

     sigaddset adds sig	to the specified set.

     sigdelset deletes sig from	the specified set.

     sigemptyset clears	all signals in the specified set.

     sigfillset	sets all signals in the	specified set.





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SIGSETOPS(3)							  SIGSETOPS(3)



     sigismember returns 1 if sig is a member of the specified set, else
     returns 0.

SGI-SPECIFIC FUNCTIONS    [Toc]    [Back]

     The following four	functions, although not	part of	the POSIX
     specification, provide additional capabilities:

     sgi_altersigs performs action on the specified signal set,	for each
     signal in sigarray. Action	may be ADDSIGS or DELSIGS (defined in
     <sys/signal.h).  The final	signal entry in	sigarray must be followed by a
     0 entry (in this way sgi_altersigs	knows how many signals to process).
     The array may include all legal signals; however, if the intent is	to set
     or	clear all signals the sigaddset	and sigdelset routines are more
     efficient.	 Any illegal signal numbers are	silently skipped.
     sgi_altersigs returns the number of signals which were processed, or -1
     with errno	set to [EINVAL]	if action is not ADDSIGS or DELSIGS.

     sgi_sigffset returns the number of	the lowest pending signal in set. If
     none are pending, it returns 0.  If clearit is non-zero, the returned
     signal is cleared in the mask.  In	this way sgi_sigffset may be used to
     sequentially examine the signals in a mask	without	duplication.

     sgi_siganyset(set)	returns	1 if any signals are set in the	specified
     mask, otherwise it	returns	0.  The	mask is	not altered.

     sgi_dumpset displays the specified	set of signals as a bit-vector,
     primarily for debugging purposes.

     For a list	of valid signal	numbers	please see signal(5).

ERRORS    [Toc]    [Back]

     In	every routine, the set parameter is a pointer to sigset_t.  All	of
     these functions are library routines (executing in	user space); therefore
     if	they are passed	a REFERENCE to set instead of a	POINTER, the compiler
     will issue	a warning, and when the	program	is run the process will
     receive a memory fault signal [SIGSEGV] and terminate (unless the process
     has installed a handler for SIGSEGV).

     All routines which	require	a sig parameter	will fail, returning -1	and
     setting errno to [EINVAL] if sig is not a valid signal number.

SEE ALSO    [Toc]    [Back]

     sigaction(2), sigprocmask(2), sigpending(2), sigsuspend(2), sigsetjmp(3),
     pthread_sigmask(3P).

WARNING    [Toc]    [Back]

     The POSIX and System V signal facilities have different semantics.	 Using
     both facilities in	the same program is strongly discouraged and will
     result in unpredictable behavior.


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