HP OpenVMS Systems

Exit Handlers, $forcex and $dclexh?

» close window

The Question is:

 
I use sys$forcex to call the exit handler of a detached process, passing in a
 status.
 
This works ok on a Vax, but on the Alpha the exit handler is called, but the
 status is not as expected.
 
Forcex code
      j_value = SS$_ABORT
      j_status = sys$forcex ( , c_proc_str(1:i_len), %val(j_value) )
 
Exit Handler
 
      PROGRAM TEST_EXIT
      IMPLICIT NONE
 
      EXTERNAL EXIT_HANDLER
 
      STRUCTURE /EXIT_DESCRIPTOR/
        INTEGER*4 J_LINK
        INTEGER*4 J_ADDR
        INTEGER*4 J_ARGS /0/
        INTEGER*4 J_ANARG
      END STRUCTURE
 
      INTEGER*4 JC_DUMMY
 
      RECORD /EXIT_DESCRIPTOR/ EXIT_DSCRPT
 
      COMMON /EXITDS/ JC_DUMMY
 
!     Declare exit handler
      EXIT_DSCRPT.J_ADDR = %LOC(EXIT_HANDLER)
      EXIT_DSCRPT.J_ANARG = %LOC(JC_DUMMY)
      CALL SYS$DCLEXH(EXIT_DSCRPT)
 
      CALL SYS$SETPRN('TEST_EXIT')
 
      CALL LIB$WAIT(20000.0)
 
      END
 
 
      SUBROUTINE EXIT_HANDLER (j_status)
      IMPLICIT NONE
 
      INTEGER*4 J_STATUS
 
      CALL EXIT (j_status)
 
      END
 
 
Any idea?

The Answer is :

 
  That the exit handler is triggered would imply the call is arriving
  correctly in the process, but that the associated data structures
  or the associated exit handler routine is somehow invalid.
 
  On of the key requirements fo the exit handler storage is that it
  is declared outside the scope of any routine; that the storage is
  declared as a COMMON or as static storage.  That appears to be
  the case here, but is common source of errors with this call.
 
  You can find a Fortran example of the sys$dclexh call in the
  Natural Language Search Assistance (AskQ) database, using a
  search string such as
 
   Fortran $dclexh call example?
 
  The support database also includes a number of other examples of
  other calls for other routines and other languages, as cited in
  the OpenVMS FAQ and elsewhere.
 
  In your case, the OpenVMS Wizard would also expect the argument count
  should be set to one (1), as you are passing the condition value to
  the exit handler routine; the exit handler has an argument.  The
  description structure is a declaration of the exit handler argument
  list and related, and must match the exit handler calling sequence.
 

  

     

     
answer written or last revised on ( 17-AUG-2004 )
     
» close window