/*
* 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.integration.hibernate4;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
import java.util.List;
import javassist.bytecode.BadBytecode;
import javassist.bytecode.Bytecode;
import javassist.bytecode.ClassFile;
import javassist.bytecode.CodeIterator;
import javassist.bytecode.MethodInfo;
import javassist.bytecode.Opcode;
import org.fakereplace.transformation.FakereplaceTransformer;
/**
* Class transformer that intercepts invocations of the HibernatePersistence create* methods.
*
* @author Stuart Douglas
*/
public class Hibernate4ClassTransformer implements FakereplaceTransformer {
public static final String PROXY_NAME = "org.fakereplace.integration.hibernate4.FakereplaceEntityManagerFactoryProxy";
@Override
public boolean transform(final ClassLoader loader, final String className, final Class<?> classBeingRedefined, final ProtectionDomain protectionDomain, final ClassFile file) throws IllegalClassFormatException, BadBytecode {
if (file.getName().equals("org.hibernate.ejb.HibernatePersistence")) {
for (MethodInfo method : (List<MethodInfo>) file.getMethods()) {
if (method.getName().equals("createContainerEntityManagerFactory")) {
//need to save the method params so we can re-use them when we re-create our EMF
final int oldMax = method.getCodeAttribute().getMaxLocals();
method.getCodeAttribute().setMaxLocals(oldMax + 2);
Bytecode s = new Bytecode(file.getConstPool());
s.addAload(1);
s.addAstore(oldMax);
s.addAload(2);
s.addAstore(oldMax + 1);
//we need to interceptor the return value
//and add in our own bytecode fragment.
//first lets create our proxy creation code
final Bytecode b = new Bytecode(file.getConstPool());
b.addNew(PROXY_NAME);
b.add(Opcode.DUP_X1);
b.add(Opcode.SWAP);
b.addAload(0);
b.addAload(oldMax);
b.addAload(oldMax + 1);
b.addInvokespecial(PROXY_NAME, "<init>", "(Ljavax/persistence/EntityManagerFactory;Lorg/hibernate/ejb/HibernatePersistence;Ljavax/persistence/spi/PersistenceUnitInfo;Ljava/util/Map;)V");
insertBeforeReturn(method, s, b);
} else if (method.getName().equals("createEntityManagerFactory") &&
method.getDescriptor().equals("(Ljava/lang/String;Ljava/util/Map;)Ljavax/persistence/EntityManagerFactory;")) {
//need to save the method params so we can re-use them when we re-create our EMF
final int oldMax = method.getCodeAttribute().getMaxLocals();
method.getCodeAttribute().setMaxLocals(oldMax + 2);
Bytecode s = new Bytecode(file.getConstPool());
s.addAload(1);
s.addAstore(oldMax);
s.addAload(2);
s.addAstore(oldMax + 1);
//we need to interceptor the return value
//and add in our own bytecode fragment.
//first lets create our proxy creation code
final Bytecode b = new Bytecode(file.getConstPool());
b.addNew(PROXY_NAME);
b.add(Opcode.DUP_X1);
b.add(Opcode.SWAP);
b.addAload(0);
b.addAload(oldMax);
b.addAload(oldMax + 1);
b.addInvokespecial(PROXY_NAME, "<init>", "(Ljavax/persistence/EntityManagerFactory;Lorg/hibernate/ejb/HibernatePersistence;Ljava/lang/String;Ljava/util/Map;)V");
insertBeforeReturn(method, s, b);
} else if (method.getName().equals("createEntityManagerFactory") &&
method.getDescriptor().equals("(Ljava/util/Map;)Ljavax/persistence/EntityManagerFactory;")) {
//need to save the method params so we can re-use them when we re-create our EMF
final int oldMax = method.getCodeAttribute().getMaxLocals();
method.getCodeAttribute().setMaxLocals(oldMax + 1);
Bytecode s = new Bytecode(file.getConstPool());
s.addAload(1);
s.addAstore(oldMax);
//we need to interceptor the return value
//and add in our own bytecode fragment.
//first lets create our proxy creation code
final Bytecode b = new Bytecode(file.getConstPool());
b.addNew(PROXY_NAME);
b.add(Opcode.DUP_X1);
b.add(Opcode.SWAP);
b.addAload(0);
b.add(Opcode.ACONST_NULL);
b.addAload(oldMax);
b.addInvokespecial(PROXY_NAME, "<init>", "(Ljavax/persistence/EntityManagerFactory;Lorg/hibernate/ejb/HibernatePersistence;Ljava/lang/String;Ljava/util/Map;)V");
insertBeforeReturn(method, s, b);
}
}
return true;
} else {
return false;
}
}
private void insertBeforeReturn(final MethodInfo method, final Bytecode s, final Bytecode b) throws BadBytecode {
final CodeIterator itr = method.getCodeAttribute().iterator();
itr.insert(s.get());
while (itr.hasNext()) {
final int pos = itr.next();
int opcode = itr.byteAt(pos);
if (opcode == Opcode.ARETURN) {
itr.insert(pos, b.get());
}
}
method.getCodeAttribute().computeMaxStack();
}
}