sigblock(3) - NetBSD Manual Pages

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SIGBLOCK(3)             NetBSD Library Functions Manual            SIGBLOCK(3)


NAME

     sigblock -- block signals


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <signal.h>

     int
     sigblock(int mask);

     int
     sigmask(signum);


DESCRIPTION

     This interface is made obsolete by: sigprocmask(2).

     sigblock() adds the signals specified in mask to the set of signals cur-
     rently being blocked from delivery.  Signals are blocked if the corre-
     sponding bit in mask is a 1; the macro sigmask() is provided to construct
     the mask for a given signum.

     It is not possible to block SIGKILL or SIGSTOP; this restriction is
     silently imposed by the system.


RETURN VALUES

     The previous set of masked signals is returned.


EXAMPLES

     The following example using sigblock():

           int omask;

           omask = sigblock(sigmask(SIGINT) | sigmask(SIGHUP));

     Becomes:

           sigset_t set, oset;

           sigemptyset(&set);
           sigaddset(&set, SIGINT);
           sigaddset(&set, SIGHUP);
           sigprocmask(SIG_BLOCK, &set, &oset);

     Another use of sigblock() is to get the current set of masked signals
     without changing what is actually blocked.  Instead of:

           int set;

           set = sigblock(0);

     Use the following:

           sigset_t set;

           sigprocmask(SIG_BLOCK, NULL, &set);


SEE ALSO

     kill(2), sigaction(2), sigprocmask(2), sigsetmask(3), sigsetops(3)


HISTORY

     The sigblock() function call appeared in 4.2BSD and has been deprecated.

NetBSD 7.1_STABLE               August 10, 2002              NetBSD 7.1_STABLE