ssignal(3C)                    DG/UX R4.11MU05                   ssignal(3C)


NAME
       ssignal, gsignal - software signals

SYNOPSIS
       #include <signal.h>

       int (*ssignal (int sig, int (*action) (int))) (int);

       int gsignal (int sig);

DESCRIPTION
       ssignal and gsignal implement a software facility similar to
       signal(2).  This facility is made available to users for their own
       purposes.

       Software signals made available to users are associated with integers
       in the inclusive range 1 through 17. A call to ssignal associates a
       procedure, action, with the software signal sig; the software signal,
       sig, is raised by a call to gsignal.  Raising a software signal
       causes the action established for that signal to be taken.

       The first argument to ssignal is a number identifying the type of
       signal for which an action is to be established. The second argument
       defines the action; it is either the name of a (user-defined) action
       function or one of the manifest constants SIGDFL (default) or
       SIGIGN (ignore).  ssignal returns the action previously established
       for that signal type; if no action has been established or the signal
       number is illegal, ssignal returns SIGDFL.

       gsignal raises the signal identified by its argument, sig:

            If an action function has been established for sig, then that
            action is reset to SIGDFL and the action function is entered
            with argument sig.  gsignal returns the value returned to it by
            the action function.

            If the action for sig is SIGIGN, gsignal returns the value 1
            and takes no other action.

            If the action for sig is SIGDFL, gsignal returns the value 0
            and takes no other action.

            If sig has an illegal value or no action was ever specified for
            sig, gsignal returns the value 0 and takes no other action.


   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |             point     safe  |
                     +---------+-----------------------------+
                     |gsignal  |     Y         N        N    |
                     |ssignal  |     Y         N        N    |
                     +---------+-----------------------------+

SEE ALSO
       signal(2), sigset(2), reentrant(3), raise(3C).


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