BlackListTransformer.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * 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.jboss.capedwarf.bytecode.blacklist;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.List;

import javassist.bytecode.ClassFile;
import org.jboss.capedwarf.bytecode.AbstractClassFileTransformer;
import org.jboss.capedwarf.shared.compatibility.Compatibility;

/**
 * Check black list
 *
 * @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a>
 */
public class BlackListTransformer extends AbstractClassFileTransformer {
    private volatile Boolean disabled;

    private List<Rewriter> rewriters = new ArrayList<Rewriter>();

    public BlackListTransformer() {
        rewriters.add(new MethodsRewriter());
    }

    protected boolean isDisabled(ClassLoader cl) {
        if (disabled == null) {
            synchronized (this) {
                if (disabled == null) {
                    Compatibility instance = Compatibility.readCompatibility(cl);
                    disabled = instance.isEnabled(Compatibility.Feature.DISABLE_BLACK_LIST);
                }
            }
        }
        return disabled;
    }

    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain domain, byte[] bytes) throws IllegalClassFormatException {
        if (isIgnoredPackage(className) || isDisabled(loader)) {
            return bytes;
        }

        LineContext.CL.set(loader);
        try {
            ClassFile file = new ClassFile(new DataInputStream(new ByteArrayInputStream(bytes)));
            for (Rewriter rewriter : rewriters) {
                rewriter.visit(file);
            }
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            file.write(new DataOutputStream(baos));
            return baos.toByteArray();
        } catch (Exception e) {
            IllegalClassFormatException icfe = new IllegalClassFormatException("Cannot rewrite class: " + className);
            icfe.initCause(e);
            throw icfe;
        } finally {
            LineContext.CL.remove();
        }
    }
}