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From: David Tannen <bluesguy@jcdisciples.org>
Subject: Re: Segmentation fault on VADSself
Date: 1999/09/02
Message-ID: <37CF1406.7CAA@jcdisciples.org>#1/1
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Date: 1999-09-02T00:00:00+00:00
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Hi,

>We have a program compiled using rational VADSself 6.2.3d on 
>HP-UX/9.07 which has always been working very well.

Hey this sounds familiar.
 
>Now, when recompiling on HP-UX/10.20 (with the same version 
>of the compiler) we get random segmentation faults. 

As Robert asked - you do have the VADSself 6.2.3d for 
HPUX 10.20?

>Nevertheless, when running the program under the debugger 
>it runs fine.

Yeah the VADS debugger is kinds of a pain on this.  Are
you using the command line debugger or a GUI one? We 
found the behaved in different manners.

>Any clue on how to solve this?

Yes.  First of all make sure you have the latest HP/UX 
ACE patches installed on your system.  If you dig deep
enough using the debugger you will eventually find that
the problem lies someplace in either the VADS runtime or
the HP/UX OS code.  Our segmentation faults went away
when we installed the ACE patches.

Another area that could be causing problems would be 
anyplace where you *might* have variant records that
are being allocated space by the following method:
1.  You have a standard record the same size as your 
    largest variant.
2.  You have access types for the standard & variant
    record.
3.  You use 'is new' to create space with the standard
    record.
4.  You then use unchecked conversion between the 
    two different access types.

You will find that the moment you try to access a
part of memory associated with the variant part of
the record, you get a core dump.

The fix is easy - do a pragma byte pack on both records.

There you go - that should save you a couple months worth
of digging.  You will be getting my bill in the morning <G>.

An ambassador for Christ
David Tannen (bluesguy@jcdisciples.org)
John 14:21 "Whoever has my commands and obeys them, he is the one who
            loves me.  He who loves me will be loved by my Father, 
            and I too will love him and show myself to him."
Check Out:   http://www.jcdisciples.org/davidtannen/index.html