1 /*

     2  * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.

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

     4  *

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

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

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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

    13  * accompanied this code).

    14  *

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

    16  * 2 along with this work; if not, write to the Free Software Foundation,

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

    18  *

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

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

    21  * questions.

    22  *

    23  */

    24 

    25 import java.lang.instrument.ClassFileTransformer;

    26 import java.lang.instrument.IllegalClassFormatException;

    27 import java.security.ProtectionDomain;

    28 

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

    30 

    31 public class InstrumentationClassFileTransformer implements ClassFileTransformer {

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

    33                             ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {

    34 

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

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

    37             try {

    38                 if (classBeingRedefined == null) {

    39                     // Initial transform

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

    41                 } else {

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

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

    44                 }

    45             } catch (Throwable t) {

    46                 t.printStackTrace();

    47             }

    48             return buffer;

    49         }

    50         return null;

    51     }

    52 

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

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

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

    56     }

    57 }