RFR: 8264990: WebEngine crashes with segfault when not loaded through system classloader [v2]

[Kevin Rushforth]

On Fri, 9 Apr 2021 20:45:33 GMT, Matthias Bläsing <github.com+2179736+matthiasblaesing at openjdk.org> wrote:

>>>  I pushed an update, that addresses the comments and updated the issue with the final issue id.
>> 
>> You also need to adjust the PR title to match the bug title exactly.
>> 
>>> I did not touch the comments on the original commits, so that history is kept intact (I understand, that skara bot will use the PR message as base for the final squashed commit and ignores the individual commits)
>> 
>> Yes, this is correct. And we prefer contributors to do just what you did for incremental changes. Thanks.
>
> I'm currently rerunning tests and preparing and update - further analysis showed, that thread attachment is handled in `WebCore::StorageThread::threadEntryPoint()`:
> 
> https://github.com/openjdk/jfx/blob/808b1078f762a923bd5e74298daffeb88ed108c2/modules/javafx.web/src/main/native/Source/WebKitLegacy/Storage/StorageThread.cpp#L76-L87
> 
> The analysis was triggered by a request from @neilcsmith-net on the netbeans mailing list. He pointed out, that the fault should have happened earlier if the the thread indeed was not attached. In that case  `GetEnv` is required to return `NULL`. From the [doc](https://docs.oracle.com/en/java/javase/11/docs/specs/jni/invocation.html#getenv):
> 
>> If the current thread is not attached to the VM, sets *env to NULL, and returns JNI_EDETACHED. If the specified version is not supported, sets *env to NULL, and returns JNI_EVERSION. Otherwise, sets *env to the appropriate interface, and returns JNI_OK.

That's good since it will simplify the fix to the root cause, which is that looking up the class fails depending on the ClassLoader used to load the JavaFX modules.

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PR: https://git.openjdk.java.net/jfx/pull/458