RFR: 8318737: Fallback linker passes bad JNI handle [v2]

[Jorn Vernee]

On Wed, 25 Oct 2023 09:32:42 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   explicitly propagate fallback library init failures
>
> src/java.base/share/native/libfallbackLinker/fallbackLinker.c line 52:
> 
>> 50:     return; // let caller deal with exception
>> 51:   }
>> 52:   LibFallback_class = (*env)->NewGlobalRef(env, LibFallback_class_local);
> 
> I think `NewGlobalRef` can return `nullptr` on OOME: https://docs.oracle.com/javase/8/docs/technotes/guides/jni/spec/functions.html#NewGlobalRef
> 
> We should check for this too?

I've improved the initialization logic of the surrounding fields as well. Now we explicitly report errors back to the caller (using a boolean return value), which can then throw an exception when the library fails to initialize.

See: https://github.com/openjdk/jdk/pull/16349/commits/dd74cdb9dbe7a05386a18156e7a174c9c8546b1a

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PR Review Comment: https://git.openjdk.org/jdk/pull/16349#discussion_r1371562428