59 lines
2.2 KiB
Java
59 lines
2.2 KiB
Java
/*
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* Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package gc.g1.unloading.bytecode;
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import java.util.*;
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/**
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* This utility class replaces peaces of bytes in bytecode by another peaces according to dictionary. This is useful for class redefenition.
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*/
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public class BytecodePatcher {
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static private Map<byte[], byte[]> dictionary = new HashMap<>();
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static {
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dictionary.put("bytesToReplace0".getBytes(), "bytesToReplace1".getBytes());
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dictionary.put("bytesToReplace2".getBytes(), "bytesToReplace3".getBytes());
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}
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public static void patch(byte[] bytecode) {
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for (Map.Entry<byte[], byte[]> entry : dictionary.entrySet()) {
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for (int i = 0; i + entry.getKey().length < bytecode.length; i++) {
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boolean match = true;
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for (int j = 0; j < entry.getKey().length; j++) {
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if (bytecode[i + j] != entry.getKey()[j]) {
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match = false;
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break;
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}
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}
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if (match) {
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for (int j = 0; j < entry.getKey().length; j++)
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bytecode[i + j] = entry.getValue()[j];
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}
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}
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}
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}
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}
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