RE: Retrieve Source of RPG Programs

[Hans Boldt <boldt@xxxxxxxxxx>]

someone on midrange-l wrote:
>I'm coming into this discussion late so forgive me if I missed something.
>Why would decompiling an ILE RPG generated program be that different from
>an OPM RPG program?    I'm no expert on de-compiling but it seems to me
>that if I can decompile an OPM program, I can de-compile an ILE program. A
>system service tools dump of the program (ILE or OPM) gives me essentially
>the same info. No?

No. As I understand it, OPM RPG decompilers work by first
extracting the MI code and looking for patterns that match
what's generated from known RPG statements.  The ILE
compilers do not use MI, but rather, a lower level
intermediate representation (called W-code) that looks very
much like machine language.  MI is a source data stream
that can be viewed directly.  W-code is a binary data
stream designed specifically for optimizing compilers.

While I'm sure it would be possible to use the same
techniques to decompile certain ILE RPG statements, for
others, especially those involving expressions, it would be
very difficult.

My point is that if you are developing a disaster recovery
plan (you DO have a disaster recovery plan, don't you?),
don't count on any ILE decompilers.

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
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