/**************************************************************************************
* Copyright (c) The AspectWerkz Team. All rights reserved. *
* http://aspectwerkz.codehaus.org *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the BSD style license *
* a copy of which has been included with this distribution in the license.txt file. *
**************************************************************************************/
package org.codehaus.aspectwerkz.hook.impl;
import org.codehaus.aspectwerkz.hook.ClassLoaderPreProcessor;
import org.codehaus.aspectwerkz.hook.ClassLoaderPatcher;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.classfile.ClassParser;
import org.apache.bcel.Constants;
import org.apache.bcel.generic.*;
import java.io.InputStream;
import java.io.ByteArrayInputStream;
/**
* Instruments the java.lang.ClassLoader to plug in the Class PreProcessor
* mechanism using BCEL.
*
* We are using a lazy initialization of the class preprocessor to allow all class
* pre processor logic to be in system classpath and not in bootclasspath
*
* @author <a href="mailto:alex@gnilux.com">Alexandre Vasseur</a>
*/
public class ClassLoaderPreProcessorImpl implements ClassLoaderPreProcessor {
public ClassLoaderPreProcessorImpl() {
}
public byte[] preProcess(byte[] b) {
try {
// Implementation note: add modified ClassLoader in bcel/lib/ and add wished class in bootclasspath
// then turn on BCELifier to learn more about BCEL
//org.apache.bcel.util.BCELifier bc = new org.apache.bcel.util.BCELifier(repository.loadClass("java.lang.ClassLoader"), System.out);
//bc.start();
final ClassGen cg = new ClassGen(
(new ClassParser(new ByteArrayInputStream(b), "<generated>")).parse());
final String className = cg.getClassName();
final Method[] methods = cg.getMethods();
final ConstantPoolGen cpg = cg.getConstantPool();
final InstructionFactory factory = new InstructionFactory(cg);
// for all methods, look for caller side "this.define0" calls
for (int i = 0; i < methods.length; i++) {
final MethodGen mg = new MethodGen(methods[i], className, cpg);
final InstructionList il = mg.getInstructionList();
if (il == null) continue;
InstructionHandle ih = il.getStart();
while (ih != null) {
final Instruction ins = ih.getInstruction();
if (ins instanceof INVOKESPECIAL
|| ins instanceof INVOKESTATIC
|| ins instanceof INVOKEVIRTUAL) {
final InvokeInstruction invokeInst = (InvokeInstruction) ins;
final String callerSideMethodClassName = invokeInst.getClassName(cpg);
final String callerSideMethodName = invokeInst.getMethodName(cpg);
//System.out.println(callerSideMethodClassName + "." + callerSideMethodName);
if ("java.lang.ClassLoader".equals(callerSideMethodClassName)
&& "defineClass0".equals(callerSideMethodName)) {
InstructionHandle ihc = il.insert(ih, factory.createStore(Type.OBJECT, 16));
ihc = il.append(ihc, factory.createStore(Type.INT, 15));
ihc = il.append(ihc, factory.createStore(Type.INT, 14));
ihc = il.append(ihc, factory.createStore(Type.OBJECT, 13));
ihc = il.append(ihc, factory.createStore(Type.OBJECT, 12));
ihc = il.append(ihc, factory.createStore(Type.OBJECT, 11));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 11));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 12));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 13));
ihc = il.append(ihc, factory.createLoad(Type.INT, 14));
ihc = il.append(ihc, factory.createLoad(Type.INT, 15));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 16));
ihc = il.append(ihc, factory.createInvoke(
"org.codehaus.aspectwerkz.hook.impl.ClassPreProcessorHelper",
"defineClass0Pre",
new ArrayType(Type.BYTE, 1),
new Type[] {
new ObjectType("java.lang.ClassLoader"),
Type.STRING,
new ArrayType(Type.BYTE, 1),
Type.INT,
Type.INT,
new ObjectType("java.security.ProtectionDomain") },
Constants.INVOKESTATIC));
ihc = il.append(ihc, factory.createStore(Type.OBJECT, 18));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 11));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 12));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 18));
ihc = il.append(ihc, new PUSH(cpg, 0));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 18));
ihc = il.append(ihc, InstructionConstants.ARRAYLENGTH);
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 16));
// call to define0 occurs here
ihc = il.append(ihc.getNext(), factory.createStore(Type.OBJECT, 17));
ihc = il.append(ihc, factory.createLoad(Type.OBJECT, 17));
}
}
ih = ih.getNext();
}
mg.setInstructionList(il);
mg.setMaxLocals();
mg.setMaxStack();
methods[i] = mg.getMethod();
}
cg.setMethods(methods);
// dump generated BCEL stuff thru BCELifier
//org.apache.bcel.util.BCELifier bc = new org.apache.bcel.util.BCELifier(cg.getJavaClass(), System.out);
//bc.start();
// dump class file
//cg.getJavaClass().dump("ClassLoader.class");
return cg.getJavaClass().getBytes();
} catch (Exception e) {
System.err.println("failed to patch ClassLoader:");
e.printStackTrace();
return b;
}
}
/**
* main test
*/
public static void main(String args[]) throws Exception {
ClassLoaderPreProcessor me = new ClassLoaderPreProcessorImpl();
InputStream is = ClassLoader.getSystemClassLoader().getParent().getResourceAsStream("java/lang/ClassLoader.class");
me.preProcess(ClassLoaderPatcher.inputStreamToByteArray(is));
is.close();
}
}