/*

 * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package vm.share.transform;

import vm.share.FileUtils;

public class TransformingClassLoader extends ClassLoader {

    private final AbstractClassFileTransformer transformer;

    protected TransformingClassLoader(ClassLoader parent,

            AbstractClassFileTransformer transformer) {

        super(parent);

        this.transformer = transformer;

    }

    @Override

    protected Class<?> loadClass(String name, boolean resolve)

            throws ClassNotFoundException {

        if (!transformer.shouldBeTransformed(name)) {

            return super.loadClass(name, resolve);

        }

        synchronized (getClassLoadingLock(name)) {

            // First, check if the class has already been loaded

            Class<?> c = findLoadedClass(name);

            if (c == null) {

                try {

                    byte[] bytes = FileUtils.readClass(name);

                    bytes = transformer.transformClass(bytes);

                    c = defineClass(name, bytes, 0, bytes.length);

                } catch (Exception e) {

                    e.printStackTrace();

                    return super.loadClass(name, resolve);

                }

            }

            if (resolve) {

                resolveClass(c);

            }

            return c;

        }

    }

}