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&...]