Help with VM Crash using the foreign linker

[Duncan McLean]

Hi Maurizio,

Thank you for the quick reply. I've made an issue on git hub. I've attached
one of the VM crash logs to it.

https://github.com/boulder-on/JPassport/issues/2

I pulled down the Panama early access build - that's what I used to make
the log that is attached to the issue.

Please let me know what else I can do to help.

Thanks!
Duncan

On Fri, May 14, 2021 at 4:44 PM Maurizio Cimadamore <
maurizio.cimadamore at oracle.com> wrote:

> Hi Duncan,
> I haven't looked in any details at your email (but I will) - sounds like
> a cool project. I wanted to share few early considerations:
>
> * attachments are dropped by the openjdk mailer - so you need to post
> them somewhere else (maybe make a Gist on Github?)
>
> * For now, Java 16 and Java 17 have exactly the same code (since we have
> not yet integrated Panama changes into 17). So you might want to try
> again with e.g. the panama early access [1].
>
> It would be helpful if we could see at least the logs of the crash. On
> top of my head I can't think of any interaction between the Java
> compiler API and the Foreign Linker API that would be causing this. And,
> while there are many things that could go wrong when working with custom
> class loaders, typically when things go wrong you end up with an
> exception, not a VM crash.
>
> But let's start from obtaining the logs, and maybe try to reproduce it,
> and then let's figure out what's wrong.
>
> Thanks for the report!
>
> Maurizio
>
>
>
> On 14/05/2021 21:20, Duncan McLean wrote:
> > Hello,
> >
> > I'm sorry if this isn't the right place to be asking for help with the
> > Foreign Linker, please let me know where I should direct this question if
> > I'm in the wrong place.
> >
> > I'm using the Foreign Linker API in a project and experiencing an odd
> > result. The project is available here:
> >
> > https://github.com/boulder-on/JPassport
> >
> > The way my code works is:
> >
> > Give JPassport an interface class that you would like to use with the
> > Foreign Linker. JPassport writes the java code required to call the
> foreign
> > library, compiles the code, and hands back an object that implements the
> > interface and calls the foreign library. (I'm trying to mimic JNA like
> > behaviour in terms of just providing an interface)
> >
> > The problem I'm seeing is in my test cases for passing data to functions
> > requiring C structures
> >
> > test_jpassport/src/jpassport/test/structs/TestUsingStructs
> >
> > For some reason, any call to the foreign library causes the VM to crash.
> > However, this only happens if I invoke the compiler. The 3 scenarios I've
> > tested are:
> >
> > 1. Normal operation: write out a .java file, use JavaCompiler to compile,
> > use URLClassloader to load the compiled class, call a foreign method ->
> > crash.
> >
> > 2. Skip compiling: write out a .java file, do not compile, use URL
> > Classloader to load the class compiled in the previous test, call a
> foreigh
> > method -> no crash, the call works perfectly.
> >
> > 3. Compile manually: Take the java code written out in step 1, add it to
> my
> > project, compile, run the program, call a foreign method -> no crash
> >
> > I've tested this with the most recent JDK 16, and the most recent JDK 17
> > early access builds. My other test cases for passing primitives and
> arrays
> > all work properly with the "normal operation".
> >
> > I'm testing using 64 bit VM's on Windows 10. I've attached one of the
> crash
> > logs for further details on my set-up.
> >
> > Is there something I'm doing wrong? Please let me know if there are any
> > other details I can provide or if there is any other way I can help
> > diagnose what's going on.
> >
> > Thank you for your help,
> > Duncan
>