Re: Re: Re: Re: Detecting finally blocks?

Yes, non-Java code will also cause plenty of heartburn. It depends on what
exactly you are trying to do; creating a simple instrumenter that Java
developers can use on their own code in a controlled environment can be
pretty straightforward, while supporting arbitrary bytecode is a different
problem entirely.

On Thu, Dec 17, 2009 at 5:41 PM, David Chase <[email protected]> wrote:

>
> On 2009-12-17, at 8:35 PM, Scott Vachalek wrote:
>
> > The finally block itself may appear multiple times due to inlining, but I
> think a catch block with null type should only be the catch-all block which
> gets created implicitly whenever a finally block is present.  Any catch
> blocks which are declared by the programmer should have the type declared in
> the source.
> >
> > This is just the habit of Java compilers though; I don't think it's
> required by the JVM spec, so it's not something you can rely upon entirely.
>  But I've never seen a null catch generated by javac for any other reason.
>  The contents of the handler (save exception, repeat finally code, throw
> saved exception) are also very predictable.
>
> Beware, slightly, of the output of code obfuscators.  There was (is, I
> think) an "industry standard benchmark" whose obfuscated classfiles
> contained non-nested overlapping PC ranges for try blocks.
>
> There's also a crypto library out there that has unbalanced
> monitorenter/monitorexit, with a branch out of the balanced register that is
> guarded by a reference to a never-true private static.
>
> I only know about these things because they gave a compiler I was working
> on digestive problems, but as a practical matter, these are not substantial
> impediments to anyone who cares to get to the code.  Obfuscation buys you
> maybe one week's protection from reverse engineering, plus a bunch of
> pissed-off compiler (and tool) writers.
>
> David
>
>
>
> --
> You receive this message as a subscriber of the [email protected] mailing list.
> To unsubscribe: mailto:[email protected]
> For general help: mailto:[email protected]?subject=help
> OW2 mailing lists service home page: http://www.ow2.org/wws
>
>

-- 
You receive this message as a subscriber of the [email protected] mailing list.
To unsubscribe: mailto:[email protected]
For general help: mailto:[email protected]?subject=help
OW2 mailing lists service home page: http://www.ow2.org/wws