Paul, Alan,
Just a quick thank you for taking a look at this so soon. I will respond
to both of you as soon as practical.
Thanks,
David
On 17/05/2018 4:00 AM, Paul Sandoz wrote:
HI,
Nice thorough work on this, surprisingly tricky in some areas esp. MHs.
Class
—
3857 * <p>If there is any error accessing the nest host, or the nest host
is
3858 * in any way invalid, then {@code this} is returned.
I am curious under what conditions this can arise. As a caller this makes me
nervous :-) Are there conditions that are worth calling it. This is related to
Alan’s comment about primitive or array classes. Its clearer when looking at
the implementation: primitive/array classes, linkage error, and the more
general nest membership validation.
3883 * @throws SecurityException
3884 * If the returned class is not the current class, and
3885 * if a security manager, <i>s</i>, is present and the caller's
3886 * class loader is not the same as or an ancestor of the class
3887 * loader for the returned class and invocation of {@link
3888 * SecurityManager#checkPackageAccess s.checkPackageAccess()}
3889 * denies access to the package of the returned class
3890 * @since 11
3891 * @jvms 4.7.28 and 4.7.29 NestHost and NestMembers attributes
3892 */
3893 @CallerSensitive
3894 public Class<?> getNestHost() {
Maybe i need more coffee, but I am struggling to see in the implementation the
checks for the case of "and the caller’s class loader is not the same as or an
ancestor of the class loader for the returned class”. Is it implied that all classes
in the nest have to be loaded from the same or from a common ancestor class loader?
so you only need to check one class in the nest against the calling class.
3984 public Class<?>[] getNestMembers() {
I still think not removing dups is a mistake as it could be a source of subtle
bugs. But i doubt at this point i can persuade you or others to change it :-)
3989 // Can't actually enable this due to bootstrapping issues
3990 // assert(members.length != 1 || members[0] == this); // expected
invariant from VM
That's interesting and frustrating!
Reflection.java
—
146 // Check for nestmate access if member is private
147 if (Modifier.isPrivate(modifiers)) {
148 // assert: isSubclassof(targetClass, memberClass)
149 // Note: targetClass may be outside the nest, but that is okay
150 // as long as memberClass is in the nest.
151 boolean nestmates = areNestMates(currentClass, memberClass);
152 if (nestmates) {
153 return true;
154 }
155 }
Trivially, you don’t need the local variable “nestmates”.
VerifyAccess.java
—
134 case PRIVATE:
135 // Rules for privates follows access rules for nestmates.
136 boolean canAccess = ((allowedModes & PRIVATE) != 0 &&
137 Reflection.areNestMates(defc,
lookupClass));
138 // FIX ME: Sanity check refc == defc. Either remove or
convert to
139 // plain assert before integration.
140 myassert((canAccess && refc == defc) || !canAccess);
141 return canAccess;
142 default:
143 throw new IllegalArgumentException("bad modifiers:
"+Modifier.toString(mods));
144 }
145 }
146 static void myassert(boolean cond) {
147 if (!cond) throw new Error("Assertion failed");
148 }
Do you plan to chase up the FIX ME now or later?
I agree with Alan about the current location of the reflection API tests. If
these tests don’t need to be hammered with various and exotic HotSpot flags i
think they are better placed to be under test/jdk/java/lang/reflect.
Thanks,
Paul.
On May 14, 2018, at 5:52 PM, David Holmes <david.hol...@oracle.com> wrote:
This review is being spread across four groups: langtools, core-libs, hotspot
and serviceability. This is the specific review thread for core-libs - webrev:
http://cr.openjdk.java.net/~dholmes/8010319-JEP181/webrev.corelibs.v1/
See below for full details - including annotated full webrev guiding the review.
The intent is to have JEP-181 targeted and integrated by the end of this month.
Thanks,
David
-----
The nestmates project (JEP-181) introduces new classfile attributes to identify
classes and interfaces in the same nest, so that the VM can perform access
control based on those attributes and so allow direct private access between
nestmates without requiring javac to generate synthetic accessor methods. These
access control changes also extend to core reflection and the
MethodHandle.Lookup contexts.
Direct private calls between nestmates requires a more general calling context
than is permitted by invokespecial, and so the JVMS is updated to allow, and
javac updated to use, invokevirtual and invokeinterface for private class and
interface method calls respectively. These changed semantics also extend to
MethodHandle findXXX operations.
At this time we are only concerned with static nest definitions, which map to a
top-level class/interface as the nest-host and all its nested types as
nest-members.
Please see the JEP for further details.
JEP: https://bugs.openjdk.java.net/browse/JDK-8046171
Bug: https://bugs.openjdk.java.net/browse/JDK-8010319
CSR: https://bugs.openjdk.java.net/browse/JDK-8197445
All of the specification changes have been previously been worked out by the
Valhalla Project Expert Group, and the implementation reviewed by the various
contributors and discussed on the valhalla-dev mailing list.
Acknowledgments and contributions: Alex Buckley, Maurizio Cimadamore, Mandy
Chung, Tobias Hartmann, Vladimir Ivanov, Karen Kinnear, Vladimir Kozlov, John
Rose, Dan Smith, Serguei Spitsyn, Kumar Srinivasan
Master webrev of all changes:
http://cr.openjdk.java.net/~dholmes/8010319-JEP181/webrev.full.v1/
Annotated master webrev index:
http://cr.openjdk.java.net/~dholmes/8010319-JEP181/jep181-webrev.html
Performance: this is expected to be performance neutral in a general sense.
Benchmarking and performance runs are about to start.
Testing Discussion:
------------------
The testing for nestmates can be broken into four main groups:
- New tests specifically related to nestmates and currently in the
runtime/Nestmates directory
- New tests to complement existing tests by adding in testcases not previously
expressible.
- For example java/lang/invoke/SpecialInterfaceCall.java tests use of
invokespecial for private interface methods and performing receiver typechecks,
so we add java/lang/invoke/PrivateInterfaceCall.java to do similar tests for
invokeinterface.
- New JVM TI tests to verify the spec changes related to nest attributes.
- Existing tests significantly affected by the nestmates changes, primarily:
- runtime/SelectionResolution
In most cases the nestmate changes makes certain invocations that were
illegal, legal (e.g. not requiring invokespecial to invoke private interface
methods; allowing access to private members via reflection/Methodhandles that
were previously not allowed).
- Existing tests incidentally affected by the nestmate changes
This includes tests of things utilising class redefinition/retransformation
to alter nested types but which unintentionally alter nest relationships (which
is not permitted).
There are still a number of tests problem-listed with issues filed against them
to have them adapted to work with nestmates. Some of these are intended to be
addressed in the short-term, while some (such as the
runtime/SelectionResolution test changes) may not eventuate.
- https://bugs.openjdk.java.net/browse/JDK-8203033
- https://bugs.openjdk.java.net/browse/JDK-8199450
- https://bugs.openjdk.java.net/browse/JDK-8196855
- https://bugs.openjdk.java.net/browse/JDK-8194857
- https://bugs.openjdk.java.net/browse/JDK-8187655
There is also further test work still to be completed (the JNI and JDI
invocation tests):
- https://bugs.openjdk.java.net/browse/JDK-8191117
which will continue in parallel with the main RFR.
Pre-integration Testing:
- General:
- Mach5: hs/jdk tier1,2
- Mach5: hs-nightly (tiers 1 -3)
- Targetted
- nashorn (for asm changes)
- hotspot: runtime/*
serviceability/*
compiler/*
vmTestbase/*
- jdk: java/lang/invoke/*
java/lang/reflect/*
java/lang/instrument/*
java/lang/Class/*
java/lang/management/*
- langtools: tools/javac
tools/javap
