/*
* Copyright 2012, Stuart Douglas, and individual contributors as indicated
* by the @authors tag.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.fakereplace.manip;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javassist.bytecode.Bytecode;
import javassist.bytecode.ClassFile;
import javassist.bytecode.CodeIterator;
import javassist.bytecode.ConstPool;
import javassist.bytecode.MethodInfo;
import javassist.bytecode.Opcode;
import org.fakereplace.logging.Logger;
import org.fakereplace.util.JumpMarker;
import org.fakereplace.util.JumpUtils;
/**
* manipulator that replaces Method.invokewith the following:
* <p/>
* <code>
* if(MethodReflection.fakeCallRequired)
* MethodReflection.invoke
* else
* method.invoke
* </code>
*
* @author stuart
*/
public class MethodReflectionManipulator implements ClassManipulator {
public static final String METHOD_NAME = "invoke";
public static final String REPLACED_METHOD_DESCRIPTOR = "(Ljava/lang/reflect/Method;Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;";
public static final String METHOD_DESCRIPTOR = "(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;";
private static final Logger log = Logger.getLogger(MethodReflectionManipulator.class);
public void clearRewrites(String className, ClassLoader loader) {
}
public boolean transformClass(ClassFile file, ClassLoader loader, boolean modifiableClass, final Set<MethodInfo> modifiedMethods) {
Set<Integer> methodCallLocations = new HashSet<Integer>();
Integer newCallLocation = null;
Integer methodReflectionLocation = null;
Integer fakeCallRequiredLocation = null;
// first we need to scan the constant pool looking for
// CONSTANT_method_info_ref structures
ConstPool pool = file.getConstPool();
for (int i = 1; i < pool.getSize(); ++i) {
// we have a method call
if (pool.getTag(i) == ConstPool.CONST_Methodref) {
String className = pool.getMethodrefClassName(i);
String methodName = pool.getMethodrefName(i);
if (className.equals(Method.class.getName())) {
if (methodName.equals("invoke")) {
// store the location in the const pool of the method ref
methodCallLocations.add(i);
// we have found a method call
// if we have not already stored a reference to our new
// method in the const pool
if (newCallLocation == null) {
methodReflectionLocation = pool.addClassInfo("org.fakereplace.reflection.MethodReflection");
int nt = pool.addNameAndTypeInfo("fakeCallRequired", "(Ljava/lang/reflect/Method;)Z");
fakeCallRequiredLocation = pool.addMethodrefInfo(methodReflectionLocation, nt);
newCallLocation = pool.addNameAndTypeInfo(METHOD_NAME, REPLACED_METHOD_DESCRIPTOR);
}
}
}
}
}
// this means we found an instance of the call, now we have to iterate
// through the methods and replace instances of the call
if (newCallLocation != null) {
List<MethodInfo> methods = file.getMethods();
for (MethodInfo m : methods) {
try {
// ignore abstract methods
if (m.getCodeAttribute() == null) {
continue;
}
CodeIterator it = m.getCodeAttribute().iterator();
while (it.hasNext()) {
// loop through the bytecode
int index = it.next();
int op = it.byteAt(index);
// if the bytecode is a method invocation
if (op == CodeIterator.INVOKEVIRTUAL) {
int val = it.s16bitAt(index + 1);
// if the method call is one of the methods we are
// replacing
if (methodCallLocations.contains(val)) {
Bytecode b = new Bytecode(file.getConstPool());
// our stack looks like Method, instance,params
// we need Method, instance, params , Method
b.add(Opcode.DUP_X2);
b.add(Opcode.POP);
b.add(Opcode.DUP_X2);
b.add(Opcode.POP);
b.add(Opcode.DUP_X2);
b.addInvokestatic(methodReflectionLocation, "fakeCallRequired", "(Ljava/lang/reflect/Method;)Z");
b.add(Opcode.IFEQ);
JumpMarker performRealCall = JumpUtils.addJumpInstruction(b);
// now perform the fake call
b.addInvokestatic(methodReflectionLocation, "invoke", REPLACED_METHOD_DESCRIPTOR);
b.add(Opcode.GOTO);
JumpMarker finish = JumpUtils.addJumpInstruction(b);
performRealCall.mark();
b.addInvokevirtual(Method.class.getName(), METHOD_NAME, METHOD_DESCRIPTOR);
finish.mark();
it.writeByte(CodeIterator.NOP, index);
it.writeByte(CodeIterator.NOP, index + 1);
it.writeByte(CodeIterator.NOP, index + 2);
it.insert(b.get());
}
}
}
m.getCodeAttribute().computeMaxStack();
modifiedMethods.add(m);
} catch (Exception e) {
log.error("Bad byte code transforming " + file.getName());
e.printStackTrace();
}
}
return true;
} else {
return false;
}
}
}