Browse Prior Art Database

Handling Error Exceptions from Source Program

IP.com Disclosure Number: IPCOM000108450D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 91K

Publishing Venue

IBM

Related People

Kleon, GC: AUTHOR [+2]

Abstract

A technique is disclosed that allows execution control to be transferred to the user program in the case of an error exception occurring in the user program or in a (library) routine called from it.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Handling Error Exceptions from Source Program

       A technique is disclosed that allows execution control to
be transferred to the user program in the case of an error exception
occurring in the user program or in a (library) routine called from
it.

      Methods to call statically or dynamically prelinked programs at
entry points are in common use.  Such methods are defined in
high-level languages and also supported by linkers and loaders.
However, in situations where entry points cannot be externalized, and
therefore pre-linked, the known methods are not applicable.  Such a
situation occurs in semantics of languages that require control to be
passed to the user program in the event of an exception.  The
error/exception handling routines provided in the global run-time
environment cannot always be linked in with the user program code
(directly or indirectly), as some languages do not have facilities
for defining of externals. A solution to the problem of transferring
control to an arbitrary instruction in the user program when an
error/exception occurs in the program or in a library function called
from it is described below.

      Though facilities to register user exception handlers and to
jump across code are available, their requirement of providing
independent routines or prelinking make them not practical for
problems such as above.

      Program execution, especially in an error/exception situation,
may be modeled as shown in the figure.  A is a main program that may
call a library routine B. Conventionally, on completion, B returns to
the instruction after the corresponding 'CALL' statement in A.  Along
with any such program execution there exists an independent routine
to handle error exception situations.  This routine is not linked
with the user program in the conventional sense but is registered
with the (operating) system's error handling facility and is entered
in an error situa...