harmony-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Alexey Varlamov" <alexey.v.varla...@gmail.com>
Subject Re: [drlvm] Non-bug difference HARMONY-1688?
Date Mon, 09 Oct 2006 12:16:04 GMT
2006/10/9, Alexey Varlamov <alexey.v.varlamov@gmail.com>:
> 2006/10/9, Alexey Varlamov <alexey.v.varlamov@gmail.com>:
> > 2006/10/9, Pavel Pervov <pmcfirst@gmail.com>:
> > > Commenting on (1) I should note, that VM generally can't determine the fact
> > > of "initiating" class loading; it can only be done in Java (except bootstrap
> > > class loader, of course).
> > I presume you mean cases of direct calls to loadClass() from executed
> > Java code. Well, the same way VM loads array classes on its own, not
> > resorting to Java loader instance. So AFAIU, neither VM nor Java have
> > 100% chance to register initiating loading singly on their own.
> >
> Hey, I found the clear specification on (1)! Look at JVMS 2nd ed, Para
> 5.3.2 - 5.3.3, it reads:
> "First, the Java virtual machine determines whether L has already been
> recorded as an initiating loader of a class or interface denoted by N.
> If so, this class or interface is C, and no class creation is
> necessary.
> Otherwise the Java virtual machine invokes loadClass(N ) on L."

[0] http://java.sun.com/docs/books/vmspec/2nd-edition/html/ConstantPool.doc.html#79441

> So this is definitely bug of DRLVM, which should be fixed mainly on VM
> side. And we may want to think how to avoid data duplication in VM and
> kernel classes on this matter...
>
> > > AFAIK, there is the bug: DRLVM does not record initiating class loader of a
> > > class. (1) is just the consequence.
> > Not really. After H-1363 (aka BBC), j.l.ClassLoader records initiated
> > classes. There may be some holes in impl (e.g. for array classes), but
> > kernel classes fulfill API contract in general.
> >
> > >
> > >
> > > On 10/9/06, Alexey Varlamov <alexey.v.varlamov@gmail.com> wrote:
> > > >
> > > > Folks,
> > > >
> > > > Would you mind to spend some time looking at HARMONY-1688? Good
> > > > knowledge of classloading and security machinery is an advantage :)
> > > >
> > > > In short, we face 2 issues in DRLVM:
> > > > 1) DRLVM itself is not aware of classes initiated (in contrast to
> > > > defined ones) by a loader, and always delegates to Java classes for
> > > > lookup (except bootstrap loader, of course). This is not really queer
> > > > behaviour, but seems incompartible with most VMs. BTW, currently this
> > > > affects implementation of jvmtiGetClassLoaderClasses(), which I
> > > > believe has a bug - it returns defined classes only.
> > > > 2) j.s.AccessController of DRLVM treats system classes (i.e. loaded by
> > > > bootstrap loader) equally with application classes while examining
> > > > execution stack, while RI seems to be simply skipping them. In other
> > > > words, DRLVM would always perform ProtectionDomain.checkPermission()
> > > > with AllPermission for bootstrap classes, and RI will omit such check
> > > > if no user classes on stack. This potentially may produce subtle
> > > > effects in security-exigent areas.
> > > >
> > > > Also, both can be considered from performance perspective, probably
> > > > having somewhat negative impact.
> > > > What do you think, how will we resolve this?
> > > >
> > > > [0] http://issues.apache.org/jira/browse/HARMONY-1688
> > > >
> > > > ---------------------------------------------------------------------
> > > > Terms of use : http://incubator.apache.org/harmony/mailing.html
> > > > To unsubscribe, e-mail: harmony-dev-unsubscribe@incubator.apache.org
> > > > For additional commands, e-mail: harmony-dev-help@incubator.apache.org
> > > >
> > > >
> > >
> > >
> >
>

---------------------------------------------------------------------
Terms of use : http://incubator.apache.org/harmony/mailing.html
To unsubscribe, e-mail: harmony-dev-unsubscribe@incubator.apache.org
For additional commands, e-mail: harmony-dev-help@incubator.apache.org


Mime
View raw message