gcj crashes if a user-thread gives up its rights

[Jost Boekemeier]

> My impression is that setuid is really intended to
> effect the whole process, not just a thread

As far as I can tell all modern thread implemtations
NPTL, BSD which I've tested change the permissions for
the current thread, only.  Everything else would not
make much sense, imho.


> You are relying on a violation of the applicable
> standards.

Not sure if that was ever a standard or documented
anywhere.  Applying the limited rights to all threads
would be useless; the only reason we've started the
new thread is to drop the rights for this session. 
Dropping the rights for all threads would trash the
whole java application.


> That aside, the garbage collector may currently run
> in any thread that allocates from the Java heap.

That makes sense.  An old version of the IBM JDK
(1.4.1) has had the same problem.  Since 1.4.2_02 and
the recent Sun JDK's this problem doesn't appear
anymore.


> Also Linuxthreads makes heavy use of signals
> internally for various

No.  Linux threads and NPTL work correctly.  The issue
is a gcj/GC issue, only.  

I think it may be possible to fix the problem in the
gc by using a different IPC mechanism instead of
sending a signal.  I will take a look at this when I
have some time.


Jost




	

	
		
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