NAME

     sigset, sigaddset, sigdelset, sigemptyset, sigfillset,  sig-
     ismember - manipulate signal sets


SYNOPSIS

     #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(const sigset_t *set, int sig)


DESCRIPTION

     The system calls that handle signals, such  as  sigaction(2)
     and  sigprocmask(2)  use  sets  of signals to keep a process
     from being interrupted by those signals  while  executing  a
     signal  handler  or  a  critical code segment.  These signal
     sets are manipulated by the following functions:

     int sigaddset(sigset_t *set, int sig)
          Add signal sig to the signal set referenced by set.

     int sigdelset(sigset_t *set, int sig)
          Remove signal sig from the  signal  set  referenced  by
          set.

     int sigemptyset(sigset_t *set)
          Initialize the signal set referenced by set to an empty
          set.

     int sigfillset(sigset_t *set)
          Initialize the signal set referenced by set to an  full
          set, i.e. all signals are in the set.

     int sigismember(const sigset_t *set, int sig)
          Return 1 if the signal sig is present in the set refer-
          enced by set, 0 otherwise.


SEE ALSO

     sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2).


DIAGNOSTICS

     All functions except sigismember return 0 on success.   Sig-
     ismember  returns  0  or  1 on success.  They return -1 with
     error code EINVAL for an invalid signal  number.   (They  do
     not  use EFAULT for a bad set address, but will simply cause
     a segmentation violation.)


AUTHOR

     Kees J. Bot (kjb@cs.vu.nl)