RFR: 8368199: Add @AOTSafeClassInitializer to jdk.internal.access.SharedSecrets

[Ioi Lam]

On Mon, 20 Oct 2025 17:40:20 GMT, Dan Heidinga <heidinga at openjdk.org> wrote:

>> These two accessors are currently not used in the AOT assembly phase. Maybe we can add an assert that the corresponding fields are null, and abort the AOT assembly otherwise?
>
> Is there a particular subset of the SharedSecrets accessors that we want to allow to be set during the assembly phase?
> 
> Is there a way we can mark the fields in SharedSecrets as allowed to be assembly initialized vs those that must be null?
> 
> The unfortunate thing is that if these fields didn't use Lambdas, they would also be fine to assembly-time initialize as it's the side-effect of the lambda forcing init that's the problem

I looked at all the calls of the pattern `SharedSecrets.set.*::`


java/io/ObjectInputFilter.java: SharedSecrets.setJavaObjectInputFilterAccess(Config::createFilter2);
java/io/ObjectInputStream.java: SharedSecrets.setJavaObjectInputStreamAccess(ObjectInputStream::checkArray);
java/io/ObjectInputStream.java: SharedSecrets.setJavaObjectInputStreamReadString(ObjectInputStream::readString);
javax/crypto/SealedObject.java: SharedSecrets.setJavaxCryptoSealedObjectAccess(SealedObject::getExtObjectInputStream);


These calls are all done inside a `<clinit>`. In the four cases, only the first class (`java.io.ObjectInputFilter.Config`) has environment-dependent code inside its `<clinit>`.

Maybe we should mark the `java.io.ObjectInputFilter.Config` class with a new annotation `AOTUnsafeClassInitializer` (the opposite of the existing `AOTSafeClassInitializer`). If this class is initialized in the assembly phase, the VM will exit.

I think we can leave the other 3 cases alone.

An alternative is to rewrite the first case from:


SharedSecrets.setJavaObjectInputFilterAccess(Config::createFilter2);


to


SharedSecrets.setJavaObjectInputFilterAccess(new JavaObjectInputFilterAccess() {
    ObjectInputFilter createFilter2(String pattern) {
        return Config.createFilter2(pattern);
    }
});

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PR Review Comment: https://git.openjdk.org/jdk/pull/27880#discussion_r2464550244