On Wed, 28 Apr 2021 21:10:33 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> wrote:
> I just did a test: > > ``` > public class TestLookup { > public static void main(String[] args) throws Throwable { > MethodHandle handle = > MethodHandles.lookup().findVirtual(CLinker.class, "downcallHandle", > MethodType.methodType(MethodHandle.class, Addressable.class, > MethodType.class, FunctionDescriptor.class)); > CLinker linker = CLinker.getInstance(); > handle.invoke(linker, MemoryAddress.NULL, > MethodType.methodType(void.class), FunctionDescriptor.ofVoid()); > } > } > ``` > > this fails as expected when the handle is invoked. To test I had to disable > the check on CLinker.getInstance - otherwise that would have always throw > anyway. My statement was overly simplified. If `handle` is invoked in another module B and invoked by a class in module B, which module (the `lookup`'s module or ) do you expect be the caller to check against for native access check? `CLinker::downcallHandle` is not caller-sensitive but its implementation is. The method handle of a caller-sensitive method behaves as if it were called from an instruction contained in the lookup class [1]. [1] https://download.java.net/java/early_access/jdk17/docs/api/java.base/java/lang/invoke/MethodHandles.Lookup.html#callsens > Also, on IllegalCaller vs. IllegalAccess - looking more, I think our impl > throws IllegalCaller - now that was done because IllegalAccess is a checked > exception and we don't want a checked exception here - but the option is > called "enableNativeAccess" - is that still ok? Yes the implementation throws `IllegalCallerException` which is why I point out this. Hmm... this seems more of `IllegalAccess` as the caller does not have access to this restricted method. OTOH, `Module::addOpens` grants deep reflection access to the named module if the caller has access. Otherwise, `IllegalCallerException` is thrown. So I think it's okay to throw ICE. Others may have a different opinion. ------------- PR: https://git.openjdk.java.net/jdk/pull/3699