rubah.runtime.classloader.DefaultClassLoader.java Source code

Introduction

Here is the source code for rubah.runtime.classloader.DefaultClassLoader.java

Source

/*******************************************************************************
 *     Copyright 2014,
 *        Luis Pina <luis@luispina.me>,
 *        Michael Hicks <mwh@cs.umd.edu>
 *     
 *     This file is part of Rubah.
 *
 *     Rubah is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     (at your option) any later version.
 *
 *     Rubah 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 General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with Rubah.  If not, see <http://www.gnu.org/licenses/>.
 *******************************************************************************/
package rubah.runtime.classloader;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;

import org.apache.commons.io.IOUtils;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;

import rubah.bytecode.transformers.AddForwardField;
import rubah.bytecode.transformers.DecreaseClassMethodsProtection;
import rubah.bytecode.transformers.RedirectFieldManipulation;
import rubah.bytecode.transformers.ReplaceOriginalNamesByUnique;
import rubah.bytecode.transformers.ReplaceUniqueByOriginalNames;
import rubah.framework.Namespace;

public abstract class DefaultClassLoader implements Opcodes {
    protected Namespace namespace;
    protected TransformerFactory factory;

    public DefaultClassLoader(Namespace namespace, TransformerFactory factory) {
        this.namespace = namespace;
        this.factory = factory;
    }

    protected byte[] getOriginalClassBytes(String className) throws IOException {
        className = "/" + className.replace('.', '/') + ".class";

        InputStream stream = DefaultClassLoader.class.getResourceAsStream(className);
        if (stream == null) {
            throw new IOException(className);
        }

        byte[] ret = IOUtils.toByteArray(stream);

        // Analyze non-updatable class
        this.analyzeClass(ret);

        return ret;
    }

    public byte[] getResource(String resourceName) throws IOException {
        InputStream stream = DefaultClassLoader.class.getResourceAsStream(resourceName);
        if (stream == null) {
            throw new IOException(resourceName);
        }

        return IOUtils.toByteArray(stream);
    }

    public byte[] getClass(String className) throws IOException {

        className = this.getOriginalClassName(className);
        if (className == null) {
            return null;
        }

        byte[] classBytes = this.getOriginalClassBytes(className);
        ClassReader reader = new ClassReader(classBytes);
        ClassWriter writer = this.getClassWriter(ClassWriter.COMPUTE_MAXS);
        ClassVisitor visitor = writer;

        HashMap<Object, String> namesMap = new HashMap<Object, String>();
        HashMap<String, Object> objectsMap = new HashMap<String, Object>();

        visitor = this.addPostTransformer(visitor);

        visitor = new ReplaceUniqueByOriginalNames(namesMap, objectsMap, this.namespace, visitor);

        visitor = this.addTransformers(visitor, objectsMap);

        visitor = new ReplaceOriginalNamesByUnique(namesMap, objectsMap, this.namespace, visitor);

        visitor = this.addPreTransformer(visitor);

        reader.accept(visitor, ClassReader.SKIP_FRAMES);

        return writer.toByteArray();
    }

    protected ClassVisitor addPreTransformer(ClassVisitor visitor) {
        return visitor;
    }

    protected ClassVisitor addPostTransformer(ClassVisitor visitor) {
        return visitor;
    }

    protected ClassWriter getClassWriter(int flags) {
        return new ClassWriter(flags);
    }

    protected ClassVisitor addTransformers(ClassVisitor visitor, HashMap<String, Object> objectsMap) {

        visitor = new AddForwardField(objectsMap, this.namespace, visitor);
        visitor = this.factory.getAddGettersAndSetters(objectsMap, this.namespace, visitor);
        visitor = new RedirectFieldManipulation(objectsMap, this.namespace, visitor);
        visitor = new DecreaseClassMethodsProtection(visitor);

        return visitor;
    }

    protected abstract String getOriginalClassName(String className);

    protected abstract void analyzeClass(byte[] classBytes);
}