Re: rt.jat instrumentation causes JVM crash

On Sat, Oct 17, 2009 at 2:09 PM, Guy Korland <[email protected]> wrote:
> Hi,
>
> I'm trying to instrument the boot class loader classes, after some
> long work I found out that adding new field to some of these classes
> breaks the JVM.
This topic is NOT related to asm, I think, :)

What "core" classes do you instrument?  It is not supported for JVM
for instrumented "core" classes, such as java.lang.Thread,
java.lang.Object.

My preferred approach is to instrument java "core" classes by ASM, and
dump them in file system as new class files.  Use -Xbootclasspath
option to replace your original "core" classes.

> So after I removed those fields and left only adding new methods to
> the boot classes I'm still getting the following error on JVM
> initialization, any ideas?
>
> Error occurred during initialization of VM
> java.lang.ExceptionInInitializerError
> Caused by: java.lang.NullPointerException
>       at java.lang.String.charAt(String.java:689)
>       at java.security.BasicPermission.init(BasicPermission.java:93)
>       at java.security.BasicPermission.<init>(BasicPermission.java:129)
>       at java.lang.RuntimePermission.<init>(RuntimePermission.java:335)
>       at java.lang.Thread.<clinit>(Thread.java:1493)
>
> Or if I don't instrument the java.lang.* classes.
>
> Error occurred during initialization of VM
> java.lang.NullPointerException
>       at java.util.Hashtable.put(Hashtable.java:394)
>       at java.lang.System.initProperties(Native Method)
>       at java.lang.System.initializeSystemClass(System.java:1072)
>
> Thanks,
> Guy
>
>
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>



-- 
Yao
GNU/Linux Developer

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