/*

 * Copyright (c) 2014, 2019, 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

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 * questions.

 *

 */

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.IllegalClassFormatException;

import java.security.ProtectionDomain;

// Note: Util is from /test/hotspot/jtreg/runtime/cds/appcds/test-classes/TestCommon.java

public class InstrumentationClassFileTransformer implements ClassFileTransformer {

    public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,

                            ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {

        if (name.startsWith("InstrumentationApp$") && !name.equals("InstrumentationApp$NotTransformed")) {

            System.out.println("Transforming: " + name + " class = " + classBeingRedefined);

            try {

                if (classBeingRedefined == null) {

                    // Initial transform

                    replace(buffer, "buzz", "fuzz");

                } else {

                    replace(buffer, "buzz", "guzz"); // Retransform

                    replace(buffer, "huzz", "quzz"); // Redefine

                }

            } catch (Throwable t) {

                t.printStackTrace();

            }

            return buffer;

        }

        return null;

    }

    static void replace(byte[] buffer, String from, String to) {

        int n = Util.replace(buffer, from, to);

        System.out.println("..... replaced " + n + " occurrence(s) of '" + from + "' to '" + to + "'");

    }

}