| /* |
| * Copyright (c) 2014, 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 gc.g1.unloading.bytecode; |
| |
| import java.io.*; |
| import java.nio.charset.*; |
| import java.util.*; |
| |
| |
| /** |
| * This BytecodeFactory produces bytecode that is golden bytecode with className substituted. |
| */ |
| public class BytecodeMutatorFactory implements BytecodeFactory { |
| |
| private static final String FILLER_CHARACTER = "_"; |
| |
| /** |
| * Utility method in this class |
| */ |
| public static String padName(String s, int length) { |
| int difference = length - s.length(); |
| StringBuilder sb = new StringBuilder(s); |
| for (int i = 0; i < difference; i++) { |
| sb.append(FILLER_CHARACTER); |
| } |
| return sb.toString(); |
| } |
| |
| public String padName(String s) { |
| return padName(s, getNameLength()); |
| } |
| |
| private final Charset CHARACTER_SET = StandardCharsets.UTF_8; |
| |
| private List<Integer> offsets = new LinkedList<>(); |
| |
| private byte[] templateBytecode; |
| |
| private String templateClassName; |
| |
| private byte[] templateClassNameAsBytes; |
| |
| public BytecodeMutatorFactory() { |
| this(DefaultTemplateClass.class.getName()); |
| } |
| |
| public BytecodeMutatorFactory(String templateClassName) { |
| this.templateClassName = templateClassName; |
| |
| // Read bytecode to array |
| InputStream is = ClassLoader.getSystemResourceAsStream(templateClassName.replace('.', '/').concat(".class")); |
| try { |
| templateBytecode = new byte[is.available()]; |
| is.read(templateBytecode); |
| is.close(); |
| } catch (IOException e) { |
| throw new RuntimeException(e); |
| } |
| |
| // Save offsets |
| templateClassNameAsBytes = templateClassName.replace('.', '/').getBytes(CHARACTER_SET); |
| for (int i = 0; i < templateBytecode.length; i++) { |
| boolean match = true; |
| for (int j = 0; j < templateClassNameAsBytes.length; j++) { |
| if (i + j >= templateBytecode.length || templateClassNameAsBytes[j] != templateBytecode[i + j]) { |
| match = false; |
| break; |
| } |
| } |
| if (match) { |
| offsets.add(i); |
| } |
| } |
| } |
| |
| public byte[] getBytecode(String className) { |
| |
| // Check size of name constraint |
| byte[] newClassNameAsBytes = className.replace('.', '/').getBytes(CHARACTER_SET); |
| if (newClassNameAsBytes.length != templateClassNameAsBytes.length) { |
| throw new RuntimeException("Can't produce bytecode with \"" + className + "\" substituted as class name. " + |
| "Length of this name differs from length of \"" + templateClassName + "\" which equals to " + templateClassName.length() + |
| ". Length of \"" + className + "\" is " + className.length() + "."); |
| } |
| |
| // Prepare bytecode |
| byte[] result = Arrays.copyOf(templateBytecode, templateBytecode.length); |
| for (int offset : offsets) { |
| System.arraycopy(newClassNameAsBytes, 0, result, offset, newClassNameAsBytes.length); |
| } |
| return result; |
| } |
| |
| public int getNameLength() { |
| return templateClassName.length(); |
| } |
| |
| @Override |
| public Bytecode createBytecode(String className) { |
| String finalClassName = padName(className); |
| byte[] bytecode = getBytecode(finalClassName); |
| return new Bytecode(finalClassName, bytecode); |
| } |
| |
| } |