Hi Harold,

I'm having a lot of issues with the code and testing here. Please bear with me.


On 19/09/2016 10:51 PM, harold seigel wrote:
Hi,

Please review this updated webrev for fixing JDK-8160987
<https://bugs.openjdk.java.net/browse/JDK-8160987>:

   http://cr.openjdk.java.net/~hseigel/bug_8160987.2/

src/jdk.jdwp.agent/share/native/libjdwp/invoker.c

+ // If not the same class then check that containing_class is a super type of
+     // clazz and not an interface (hence it's a super class).

Simpler to just say:

+ // If not the same class then check that containing_class is a superclass of
+     // clazz (not a superinterface).

Took me a while to notice that interfaces don't inherit static methods from superinterfaces either!

---

test/com/sun/jdi/InterfaceMethodsTest.java

The new comments are very verbose compared to other negative tests:

200 // try to invoke static method A on the instance. This should fail because ref 201 // is of type InterfacemethodsTest$TargetClass which is not a subtype of the
 202         // class containing staticMethodA.

Could simply be:

200 // "staticMethodA" is not inherited by TargetClass


That aside the more I look at this test the more things I see that seem to be wrong or at the very least confused, in the existing code. First it seems that the test chooses to ignore the "class" object when given a non-null ref object - so it talks about invoking a static method on an instance, which is misleading at best as what it will actually do is take a path that tries to invoke the static method using the instances' class instead of the specified class (which may be the interface class). This makes the test descriptions and expected behaviours somewhat unintuitive in my opinion.

 244         // "staticMethodA" must not be inherited by InterfaceB
245 testInvokeNeg(ifaceClass, null, "staticMethodA", "()I", vm().mirrorOf(RESULT_A),
 246                 "Static interface methods are not inheritable");

I am wondering how this test passes without your fix? It suggests there must already exist some code that compares the declaring class with the passed in class. ??

248 // however it is possible to call "staticMethodA" on the actual instance 249 testInvokeNeg(ifaceClass, ref, "staticMethodA", "()I", vm().mirrorOf(RESULT_A),
 250                 "Static interface methods are not inheritable");

The comment here suggests a successful execution when in fact it expects it to fail. It should say "nor is it possible ...". But again, how does this pass (by failing) without your fix ???

252         // "staticMethodB" is overridden in InterfaceB

"overridden" is the wrong word here. Static interface methods are not inherited so they can not be overridden. "re-defined" would be an accurate description.

Similarly:

255 // the instance invokes the overriden form of "staticMethodB" from InterfaceB

overridden -> re-defined

298         /* Static method calls */

This starts all the static method calls on the instance class - all of which are expected to fail, and do so _without_ your fix present! How?

Thanks,
David
-----


It provides a more efficient implementation and fixes a test problem.
This fix was tested as described below and with the JTReg JDK
com/sun/jdi tests.

Thanks, Harold


On 9/16/2016 10:32 AM, harold seigel wrote:
Hi Serguei,

Thanks for the suggestion!  That provides a much cleaner implementation.

Harold


On 9/15/2016 11:28 PM, serguei.spit...@oracle.com wrote:
On 9/15/16 19:13, David Holmes wrote:
On 16/09/2016 8:52 AM, serguei.spit...@oracle.com wrote:
Hi Harold,

I did not got deep into the fix yet but wonder why the JVMTI
function is

My copy-paste failed.
I wanted to list the JVMTI function name: GetMethodDeclaringClass.

Thanks,
Serguei



not used.

I was wondering a similar thing. It seems very heavyweight to use
Java level reflection from inside native code to validate the native
"handles" passed to that native code. I would have expected a way to
go from a MethodId to the declaring class of the method, and a
simple way to test if there is an ancestor relation between the two
classes.

On 9/15/16 13:05, harold seigel wrote:
One could argue that a spec compliant JNI implementation wouldn't
need
this change in the first place...

Regardless, I'm withdrawing this change because I found that it fails
a com/sun/jdi JTreg test involving static methods in interfaces.

I find it both intriguing and worrying that ClassType.InvokeMethod
refers to superinterfaces when prior to 8 (and this spec was not
updated in this area) static interface methods did not exist! The
main changes were in the definition of InterfaceType.InvokeMethod. I
wonder whether invocation of static interface methods via
ClassType.InvokeMethod is actually tested directly?

I realize the specs are a bit of a minefield when it comes to what
is required by the different specs and what is implemented in
hotspot. Unfortunately it is a minefield I also have to wade through
for private interface methods. In many cases it is not clear what
should happen and all we have to guide us is what hotspot does (eg
"virtual" invocations on non-virtual methods).

David
-----


Thanks, Harold


On 9/15/2016 3:37 PM, Daniel D. Daugherty wrote:
On 9/15/16 12:10 PM, harold seigel wrote:
(Adding hotspot-runtime)

Hi Dan,

Thanks for looking at this.

I could pass NULL instead of clazz to ToReflectMethod() to ensure
that the method object isn't being obtained from clazz.

I don't think that would be a JNI spec compliant use of the
JNI ToReflectedMethod() function. That would be relying on
the fact that HotSpot doesn't use the clazz parameter to
convert {clazz,jmethodID} => method_object.

Sorry... again...

Dan



Harold


On 9/15/2016 1:09 PM, Daniel D. Daugherty wrote:
On 9/15/16 9:31 AM, harold seigel wrote:
Hi,

Please review this small fix for JDK-8160987.  The JDWP
InvokeStatic() method was depending on the JNI function that it
called to enforce the requirement that the specified method must
be a member of the specified class or one of its super classes.
But, JNI does not enforce this requirement. This fix adds code to
JDWP to do its own check that the specified method is a member of
the specified class or one of its super classes.

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8160987

Open webrev: http://cr.openjdk.java.net/~hseigel/bug_8160987/

src/jdk.jdwp.agent/share/native/libjdwp/invoker.c
    Sorry I didn't think of this comment during the pre-review...

    The only "strange" part of this fix is:

    L374:     /* Get the method object from the method's
jmethodID. */
    L375:     method_object =
JNI_FUNC_PTR(env,ToReflectedMethod)(env,
    L376: clazz,
    L377: method,
    L378: JNI_TRUE /* isStatic */);
    L379:     if (method_object == NULL) {
    L380:         return JVMTI_ERROR_NONE; /* Bad jmethodID ? This
will be handled elsewhere */
    L381:     }

    Here we are using parameter 'clazz' to find the
method_object for
    parameter 'method' so that we can validate that 'clazz'
refers to
    method's class or superclass.

    When a bogus 'clazz' value is passed in by a JCK test, the
only
    reason that JNI ToReflectedMethod() can still find the right
    method_object is that our (HotSpot) implementation of JNI
    ToReflectedMethod() doesn't really require the 'clazz'
parameter
    to find the right method_object. So the 'method_object'
that we
    return is the real one which has a 'clazz' field that doesn't
    match the 'clazz' parameter.

    Wow does that twist your head around or what?

    So we're trusting JNI ToReflectedMethod() to return the right
    method_object when we give it a potentially bad 'clazz' value.

    So should we use JNI FromReflectedMethod() to convert the
    method_object back into a jmethodID and verify that jmethodID
    matches the one that we passed to check_methodClass()?

I might be too paranoid here so feel free to say that enough is
enough with this fix.

Thumbs up!

Dan



The fix was tested with the two failing JCK vm/jdwp tests listed
in the bug, the JCK Lang, VM, and API tests, the hotspot JTReg
tests, the java/lang, java/util and other JTReg tests, the
co-located and non-colocated NSK tests, and with the RBT Tier2
tests.

Thanks, Harold









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