[jboss-user] [Javassist] - Javassist 3.15.0-GA, StackOverflowError with $sig in call to static method, can anyone confirm?

[Wanja Gayk]

Wanja Gayk [http://community.jboss.org/people/wgayk] created the discussion

"Javassist 3.15.0-GA, StackOverflowError with $sig in call to static method, can anyone confirm?"

To view the discussion, visit: http://community.jboss.org/message/643454#643454

--------------------------------------------------------------
Cheers,

here's an Example of a possible bug I've found.
Could anyone confirm this or prove me an idiot, so I can either file a bug report or go kill myself in shame?

Using $sig or $class as method parameter only seems to work on nonstatic methods, on static methods I get a StackOverflow Error.
Have I missed something in the dicumentation or is that a serious bug?

I could reproduce this with the latest JRE6 and the current JRE7:

Using $sig:

instrumenting class: de/plush/brix/instrumentation/Main (995 bytes)
instrumenting class: javassist/runtime/Desc (3280 bytes)
Exception in thread "main" java.lang.StackOverflowError
 at javassist.runtime.Desc.getParams(Desc.java)
 at javassist.runtime.Desc.getParams(Desc.java)
 at javassist.runtime.Desc.getParams(Desc.java)
[..]

Using $class:

instrumenting class: de/plush/brix/instrumentation/Main (995 bytes)
instrumenting class: javassist/runtime/Desc (3280 bytes)
Exception in thread "main" java.lang.StackOverflowError
 at javassist.runtime.Desc.getClazz(Desc.java)
 at javassist.runtime.Desc.getClazz(Desc.java)
[...]

Compile the following code, create JAR-File, have a manifest like:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.2
Created-By: 1.7.0_02-b13 (Oracle Corporation)
Premain-Class: de.plush.brix.instrumentation.Agent
Class-Path: javassist.jar

Start some Main.class with the jvm-arg:
-javaagent:${project_loc}\Agent.jar

And watch it happen.

package de.plush.brix.instrumentation;

public class Main {
 void foo() {
  System.out.println("Hello world");
  }
 public static void main(final String[] args) {
  new Main().foo();
 }
}

package de.plush.brix.instrumentation;

import java.io.IOException;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.lang.reflect.Modifier;
import java.security.ProtectionDomain;
import java.util.Arrays;

import javassist.ByteArrayClassPath;
import javassist.CannotCompileException;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.NotFoundException;

public class Agent implements ClassFileTransformer {

 public Agent(final String agentArgs, final Instrumentation instrumentation) {
  instrumentation.addTransformer(this);
 }

 public static void premain(final String agentArgs, final Instrumentation inst) {
  new Agent(agentArgs, inst);
 }

public static void before(Class[] paramTypes) { //works
 System.out.println("test passed");
 }

public static void before(Class paramTypes) { //works
 System.out.println("test passed");
 }

public static void beforeStatic(Class[] paramTypes) { //stackOverflow
  System.out.println("test passed");
 }

public static void beforeStatic2(Class paramTypes) { //stackOverflow
 System.out.println("test passed");
 }

 @Override
 public byte[] transform(final ClassLoader loader, final String className, final Class<?> classBeingRedefined, final ProtectionDomain protectionDomain,
 final byte[] classfileBuffer) throws IllegalClassFormatException {

  System.out.println("instrumenting class: " + className + " (" + classfileBuffer.length + " bytes)");

  try {
  final String javaClassName = className.replace('/', '.');
  // turn bytecodes into a Javassist CtClass
  final CtClass clazz = createClass(classfileBuffer, javaClassName);
  // add output at the beginning and end of each method
  for (final CtMethod method : clazz.getMethods()) {
   if (!isInherited(javaClassName, method)) {
     if (Modifier.isStatic(method.getModifiers())) {
      method.insertBefore("{"+Agent.class.getName() + ".beforeStatic($sig);}"); // -- $sig kills it!, also $class
      // method.insertBefore("{"+Agent.class.getName() + ".beforeStatic2($sig);}"); // -- kills it too!
     } else {
      method.insertBefore("{"+Agent.class.getName() + ".before($sig);}"); // -- $sig kills it!, also $class
      // method.insertBefore("{"+Agent.class.getName() + ".before2($class);}"); // -- kills it too!
    }
   }
  }
  return clazz.toBytecode();
 } catch (final NotFoundException e) {
   throw new RuntimeException(e);
 } catch (final CannotCompileException e) {
   if (!e.getMessage().contains("no method body")) {
    throw new RuntimeException(e);
   }
  // don't care
 } catch (final IOException e) {
  throw new RuntimeException(e);
 }
 return classfileBuffer;
 }

private boolean isInherited(final String javaClassName, final CtMethod method) {
  return !method.getLongName().startsWith(javaClassName);
 }

 private CtClass createClass(final byte[] classfileBuffer, final String javassistClassName) throws NotFoundException {
 final ClassPool cp = ClassPool.getDefault();
 cp.insertClassPath(new ByteArrayClassPath(javassistClassName, classfileBuffer));
 final CtClass cc = cp.get(javassistClassName);
 return cc;
 }
}
--------------------------------------------------------------

Reply to this message by going to Community
[http://community.jboss.org/message/643454#643454]

Start a new discussion in Javassist at Community
[http://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2062]

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/jboss-user/attachments/20111227/65249026/attachment-0001.html