On 12/12/2013 18:29, Mandy Chung wrote:
JDK-8021368: Launch of Java Web Start app fails with
ClassCircularityError exception in 7u25
https://bugs.openjdk.java.net/browse/JDK-8021368
This is a fix for 7u60 only. It's a regression in 7u25 due to
JDK-8010117 where it calls Class.getMethod to determine if the
checkMemberAccess method is overridden in a SecurityManager subclass
but Class.getMethod causes parameter types and returned type of other
public methods to be resolved and hence ClassCircularityError. It is
not an issue in JDK 8 as SecurityManager.checkMemberAccess is
deprecated and not called by the JDK (see JDK-8007035).
Webrev at:
http://cr.openjdk.java.net/~mchung/jdk7u/webrevs/8021368/webrev.00/
An alternative implementation is to add a new VM entry point to look
up the declaring class of an overridden method instead of using
JNI_GetMethodID and get a reflective method for a faster query. Since
this check is only performed once in most cases, this performance cost
of using JNI is not too bad that the new VM entry point doesn't
necessarily buy much more.
I looked at changes and the approach seems okay to me (at least I can't
of other ways to check for the override without also tickling the issue.
I think you are right that a special entry point for this is excessive
given that the result can be cached.
A minor point on the SecurityManagerHelper constructor, shouldn't it be:
boolean overridden = false;
if (smgr.getClass() != SecurityManager.class) {
try { overridden = ... }
}
A minor comment on naming where "cache" seems a bit general given that
Class has several caches (I know useCaches is general too). Also I see
the new code is using "smgr" whereas everywhere every seems to be using
"sm", "security" or other.
-Alan.
