Help with VM Crash using the foreign linker

[Duncan McLean]

Hi Jorn,

Thank you for the suggestion. I've looked into this and the
FunctionDescriptor is exactly as you have suggested:
 FunctionDescriptor.of(C_DOUBLE, C_POINTER).

I went so far as to hard code FunctionDescriptor call when I was running my
TestUsingStructs test case. The FunctionDescriptor is build at:

https://github.com/boulder-on/JPassport/blob/ddaf4482045b83be95000e7fcc240bf720f0b525/jpassport/src/main/java/jpassport/PassportFactory.java#L89

For some reason I can only run my test cases from my IDE, maven doesn't
like something I'm doing (right now it finds my test classes, but no test
cases). However, when run from the IDE, TestUsingStructs crashes the vm
every time on the first invokeExact call it encounters. When I comment out
the deleting of previously compiled files and the compiling of new files
(such that the test runs with the last compiled version) the test case
always works.

Line for deleting previous compiles:
https://github.com/boulder-on/JPassport/blob/ddaf4482045b83be95000e7fcc240bf720f0b525/jpassport/src/main/java/jpassport/PassportWriter.java#L535

Line for compiling new classes:
https://github.com/boulder-on/JPassport/blob/ddaf4482045b83be95000e7fcc240bf720f0b525/jpassport/src/main/java/jpassport/PassportWriter.java#L551

Is there any more detailed logging I can generate?

Thanks again,
Duncan

On Sat, May 15, 2021 at 9:36 AM Jorn Vernee <jorn.vernee at oracle.com> wrote:

> Hi,
>
> Looking at the crash log, as well as the test, you seem to be passing a
> single struct to a native function, but the stack trace in the error log
> shows that the call is not being intrinsified, which should not be the
> case if you're only passing a single struct on Windows. Either it fits
> in a register, or it's passed by reference, both of which cases are
> intrinsified.
>
> The most likely explanation for that seems to be that you are not using
> the right FunctionDescriptor when linking, and a crash occurs when the
> native code is trying to access what it thinks is a pointer to a struct.
> This is undefined behavior territory, which could explain why the crash
> only occurs in certain scenarios.
>
> My advice would be to check the FunctionDescriptor you're using for the
> linkage request, and make sure it matches the native function
> declaration. Looking at [1], the FunctionDescriptor you need is
> FunctionDescriptor.of(C_DOUBLE, C_POINTER).
>
> HTH,
> Jorn
>
> [1] :
>
> https://github.com/boulder-on/JPassport/blob/52bfa8b4390fdde57582722a1c8098958088de08/fl_dll/library.c#L330
>
>