inject bytecode into java native classes

[Lee Ming]

Hi,

Thank you for your reply,
Actually I have located the class file, it's inside a file named rt.jar
It's seem like I can build a new StringBuilder class which extends
from the original with some new method, update the new class into rt.jar
and Java still works pretty well. I can use the new methods from
StringBuilder

There's still one important issue, if I try to use ASM, to probe for
any special signature in any native class, for example java.lang.String
then insert a few bytecodes which will invoke static to the newly 
created method inside java.lang.StringBuilder. The result is the JVM 
will crash each time it starts up with message:

 # A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00000000, pid=7356, tid=1576
#
# JRE version: 6.0_17-b04
# Java VM: Java HotSpot(TM) Client VM (14.3-b01 mixed mode windows-x86 )
# Problematic frame:
# C  0x00000000

The ASM code works perfectly well with non-native classes,

Is there hint for this issue ?

Thank you
Bhm

> Date: Tue, 5 Jul 2011 17:51:06 +0400
> From: Dmitry.Samersoff at oracle.com
> To: wonderer_101 at live.com
> CC: serviceability-dev at openjdk.java.net
> Subject: Re: inject bytecode into java native classes
> 
> On 2011-07-05 16:37, Lee Ming wrote:
> > Hi,
> >
> > I'm trying to do some experiment with the native classes, for example
> > java.lang.StringBuilder.
> > I intend to inject some bytecodes into the class, but I could not find
> > the location of the class
> > file. Anyone can point out ?
> 
> see below (error handling is omitted)
> 
>          clz = Class.forName(p_className.replace('/', '.'));
>          ClassLoader loader = ProfilerAgent.class.getClassLoader();
>          URL classURL = loader.getResource(p_className + ".class");
> 
>          InputStream fis;
> 
>          if (classURL.getProtocol().equals("file")) {
>              File f = new File(classURL.getFile());
>              fis = new FileInputStream(f);
>          } else {
>              URLConnection conn = classURL.openConnection();
>              fis = conn.getInputStream();
>          }
> 
> Then use ASM to do instrumentation.
> 
> -- 
> Dmitry Samersoff
> Java Hotspot development team, SPB04
> * There will come soft rains ...
 		 	   		  
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