sigsetops(3C)                                       sigsetops(3C)



NAME
     sigemptyset, sigfillset, sigaddset, sigdelset, sigismember -
     manipulate signal sets

SYNOPSIS
     #include <signal.h>

     int sigemptyset (set)
     sigset_t *set;

     int sigfillset (set)
     sigset_t *set;

     int sigaddset (set, signo)
     sigset_t *set;
     int signo;

     int sigdelset (set, signo)
     sigset_t *set;
     int signo;

     int sigismember (set, signo)
     sigset_t *set;
     int signo;

DESCRIPTION
     The POSIX sigsetops primitives manipulate sets of signals.
     They operate on data objects addressable by the application,
     not on any set of signals known to the system, such as the
     set blocked from delivery to a process or the set pending
     for a process (see <signal.h>).

     The sigemptyset function initializes the signal set pointed
     to by the argument set, such that all signals defined in the
     system are excluded.  (See signal(5) for a list of defined
     signals.)

     The sigfillset function initializes the signal set pointed
     to by the argument set, such that all signals defined in the
     system are included.

     The sigaddset and sigdelset functions respectively add and
     delete the individual signal specified by the value of the
     argument signo from the signal set pointed to by the argu-
     ment set.

     The sigismember function tests whether the signal specified
     by the value of the argument signo is a member of the set
     pointed to by the argument set.

NOTES
     Applications should call either sigempyset or sigfillset at



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sigsetops(3C)                                       sigsetops(3C)



     least once for each object of type sigset_t prior to any
     other use of that object.  If such an object is not initial-
     ized in this way, but is nontheless supplied as an argument
     to any of the sigaddset, sigdelset, sigismember, sigaction,
     sigprocmask, sigpending, or sigsuspend functions, the
     results are undefined.

RETURN VALUE
     Upon successful completion, the sigismember function returns
     a value of one if the specified signal is a member of the
     specified set, or a value of zero if it is not.  Upon suc-
     cessful completion, the other functions return a value of
     zero.  For all of the above functions, if an error is
     detected, a value of -1 is returned and errno is set to
     indicate the error.

ERRORS
     If the following condition is detected, the sigaddset, sig-
     delset, and sigismember functions will return -1 and set
     errno to the following value:

     [EINVAL]       The value of the signo argument is an invalid
                    or unsupported signal number.

     If the following condition is detected, the sigfillset func-
     tion will return -1 and set errno to the following value:

     [EFAULT]       set points to an invalid address.

SEE ALSO
     sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2),
     signal(5).























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