ssignal(3)                          CLIX                          ssignal(3)



  NAME

    ssignal, gsignal - Signals the software

  LIBRARY

    Standard C Library libc.a

  SYNOPSIS

    #include <signal.h>

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

    int gsignal(
      int sig );

  PARAMETERS

    action   The name of a user defined action function or one of the
             constants SIG_DFL or SIG_IGN

    sig      An integer representing the type of signal

  DESCRIPTION

    The ssignal() and gsignal() functions form part of the C Programming
    Language Utilities.  They implement a software facility similar to the
    signal() function.  This facility, used by the Standard C Library, allows
    users to indicate the disposition of error conditions and 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 16.  A call to the ssignal() function
    associates a procedure or action with the software signal sig.  The sig
    software signal is alerted by a call to the gsignal() function.  Creating
    a software signal causes the action established for that signal to be
    taken.

    The first argument to the ssignal() function 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 SIG_DFL (default) or
    SIG_IGN (ignore).

    The gsignal() function creates a signal identified by its argument, sig.
    If an action function has been established for sig, then that action is
    reset to SIG_DFL, and the action function is entered with the argument
    sig.



  2/94 - Intergraph Corporation                                              1

  ssignal(3)                          CLIX                          ssignal(3)



  EXAMPLES

    The following example demonstrates how an action may be defined for a
    given signal and then executes later by raising that signal:

    signal_hit(sig)
    int sig;
    {
         printf("signal %d received\n", sig);
    }
            .
            .
            .
         ssignal(1, signal_hit);
            .
            .
            .
         gsignal(1);


  CAUTIONS

    There are signals with numbers outside the range 1 through 16 which are
    used by the Standard C Library to indicate error conditions.  Thus, some
    signal numbers outside the range 1 through 16 are legal, although their
    use may interfere with the operation of the Standard C Library.

  RETURN VALUES

    The ssignal() function returns the action previously established for that
    signal type.  If no action has been established or the signal number is
    illegal, this ssignal() function returns SIG_DFL.

    The gsignal() function returns the value returned to it by the action
    function.  If the action for sig is SIG_IGN, the gsignal() function
    returns the value 1 and takes no other action.

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

  ERRORS

    There are signals with numbers outside the range 1 through 16 that are
    used by the Standard C Library to indicate error conditions.

  RELATED INFORMATION

    Functions:  signal(2), sigset(2)




  2                                              Intergraph Corporation - 2/94