Procedure

   gfinth_c ( GF, interrupt signal handler ) 

   void gfinth_c ( int sigcode )

Abstract

   Respond to the interrupt signal SIGINT: save an indication
   that the signal has been received. This routine restores
   itself as the handler for SIGINT.

Required_Reading

   GF

Keywords

   GEOMETRY
   SEARCH
   UTILITY

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   sigcode    I   Interrupt signal ID code.

Detailed_Input

   sigcode     is a signal code. `sigcode' is expected to be the ANSI C
               parameter SIGINT, which represents the interrupt signal.

Detailed_Output

   None.

Parameters

   None.

Exceptions

   1)  If `sigcode' is not SIGINT, the error SPICE(INVALIDSIGNAL)
       is signaled (in the SPICE error handling sense).

   2)  If the call to the ANSI C function `signal' made
       by this routine fails, the error SPICE(SIGNALFAILED)
       is signaled (via SPICE error handling).

Files

   None.

Particulars

   This interrupt handler should be used by routines that
   participate in GF interrupt handling. Such routines should
   call the ANSI C library routine `signal' with the ANSI C
   macro SIGINT and this routine as the input arguments.

   When this routine executes, it re-establishes itself as the
   handler for the interrupt signal SIGINT. Code that uses
   CSPICE interrupt handling must restore the previous
   handler before returning.

   Once this routine is established as the handler for the
   interrupt signal SIGINT, the GF "bail out" test routine
   gfbail_c will return SPICETRUE until the interrupt status
   is cleared via a call to gfclrh_c.

Examples

   The numerical results shown for this example may differ across
   platforms. The results depend on the SPICE kernels used as input,
   the compiler and supporting libraries, and the machine specific
   arithmetic implementation.

   1) Make this routine the GF signal handler, then restore
      the previous handler. This example serves only to
      demonstrate the use of signal; the example code
      performs no useful function.


      Example code begins here.


      /.
         Program gfinth_ex1
      ./
      #include <stdio.h>
      #include <signal.h>
      #include "SpiceUsr.h"

      int main()
      {
         /.
         Prototypes
         ./
         static void      ( * previousHandler )(int);
         static void      ( * handlerPtr      )(int);

         /.
         Make gfinth_c the handler for the SIGINT signal.
         ./
         previousHandler = signal ( SIGINT, gfinth_c );

         if ( previousHandler == SIG_ERR )
         {
            setmsg_c ( "Attempt to establish gfinth_c as the "
                       "handler for the SIGINT signal failed." );
            sigerr_c ( "SPICE(SIGNALFAILED)"                   );
         }
         printf( "gfinth_c has been established as handler "
                 "for SIGNIT signal.\n"                     );

         /.
         Restore the previous handler.
         ./
         handlerPtr = signal ( SIGINT, previousHandler );

         if ( handlerPtr == SIG_ERR )
         {
            setmsg_c ( "Attempt to re-establish the previous "
                       "handler for the SIGINT signal failed." );
            sigerr_c ( "SPICE(SIGNALFAILED)"                   );
         }
         printf( "The previous handler has been re-established "
                 "for SIGNIT signal.\n"                        );

         return ( 0 );
      }


      When this program was executed on a Mac/Intel/cc/64-bit
      platform, the output was:


      gfinth_c has been established as handler for SIGNIT signal.
      The previous handler has been re-established for SIGNIT signal.

Restrictions

   None.

Literature_References

   None.

Author_and_Institution

   N.J. Bachman        (JPL)
   J. Diaz del Rio     (ODC Space)

Version

   -CSPICE Version 1.0.1, 05-AUG-2021 (JDR)

       Edited the header to comply with NAIF standard. Extended
       code example to generate outputs and provided example's solution.

   -CSPICE Version 1.0.0, 25-FEB-2009 (NJB)

Index_Entries

   GF handle interrupt signal