Re: Catch all exception handler

Remi,

I known that. But I need the try-catch block to avoid the "abruptly" method
termination due to exceptions. After a good sleep I realized that I should
 not simply catch all RuntimeExceptions but catch all Exceptions (or even
all Throwable errors). This workaround is not to deal with implicit
exceptions as I said, but to deal with unhandled exceptions (that may or
not be implicit).

Remember that my instrumentation process will add code for each method
before all ATHROW/xRETURN instructions. Without the try-catch block the
method can exit without call my added instrumentation.

On Mon, May 1, 2017 at 7:18 AM, Remi Forax <[email protected]> wrote:

> Roberto,
> the VM has no concept of checked or runtime exception, it's the java
> compiler that makes a difference.
> So i believe you do not need a try/catch.
>
> Rémi
>
> ------------------------------
>
> *De: *"Roberto Andrioli" <[email protected]>
> *À: *[email protected]
> *Envoyé: *Lundi 1 Mai 2017 05:16:48
> *Objet: *[asm] Catch all exception handler
>
> Hello all,
> I'm trying to add a catch-all exception handler using ASM core API. My
> idea is simply catch all RuntimeExceptions and re-throw. Something like:
>
> ```
> try {
>     original_code;
> } catch (RuntimeException e) {
>     throw e;
> }
> ```
>
> One may argue why? The answer is simple. My instrumentation process is
> adding code just before xRETURN and ATHROW. This workaround is to deal with
> implicit exceptions.
>
> I already implemented a 'working' POC that can be found here:
> https://github.com/saeg/ba-dua/commit/5ec4f340158f8c062e8fb94bbd1b99
> 9dcfbf85b9
>
> But in this commit I found a few issues. The main ones regarding
> unconformity with ASM core API and method call order. Note that I'm calling
>  visitTryCatchBlock(...) after visit the labels.
>
> I can't simply call visitTryCatchBlock(...) before visitLabel(start) in
> visitCode() method. This will register a new handler at the beginning of
> the exception table which precedence over all other try-catch blocks.
>
> So my solution came in the following commit: https://github.com/
> saeg/ba-dua/commit/4cec4cab0fc1c8ca9b49db28d63b4764fe671bc6
>
> The code tries to add the new try-catch block after all existing ones.
> There other comments in the git commit message describing the issues.
>
> I suppose this is a very common transformation used by ASM clients, so I
> ask you to feedback. Is this code right? or it's buggy? There others better
> way to achieve this?
>
> I appreciate any feedback.
>
> Roberto
>
>
>
>
>
>
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