1 /* 2 * Copyright (c) 2018, 2019, 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.jfr.event.oldobject; 27 28 import java.io.IOException; 29 import java.io.InputStream; 30 import java.util.ArrayList; 31 import java.util.List; 32 33 /* 34 * A special class loader that will, for our test class, make sure that each 35 * load will become a unique class 36 */ 37 public final class TestClassLoader extends ClassLoader { 38 39 public static final class TestClass0000000 { 40 public static final byte[] oneByte = new byte[1]; 41 } 42 43 static byte[] classByteCode = readTestClassBytes(); 44 private static int classIdCounter; 45 46 TestClassLoader() { 47 super(TestClassLoader.class.getClassLoader()); 48 } 49 50 public List<Class<?>> loadClasses(int count) throws Exception { 51 List<Class<?>> classes = new ArrayList<>(); 52 for (int i = 0; i < count; i++) { 53 String className = "jdk.jfr.event.oldobject.TestClassLoader$"; 54 className += "TestClass" + String.format("%07d", classIdCounter++); 55 Class<?> clazz = Class.forName(className, true, this); 56 classes.add(clazz); 57 } 58 return classes; 59 } 60 61 @Override 62 protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { 63 // If not loading the test class, just go on with the normal class loader 64 if (!name.contains("TestClass")) { 65 return super.loadClass(name, resolve); 66 } 67 String[] classNameParts = name.split("\\$"); 68 String newName = classNameParts[1]; 69 String oldName = "TestClass0000000"; 70 if (oldName.length() != newName.length()) { 71 throw new AssertionError("String lengths don't match. Unable to replace class name"); 72 } 73 byte[] newBytes = classByteCode.clone(); 74 replaceBytes(newBytes, oldName.getBytes(), newName.getBytes()); 75 Class<?> c = defineClass(name, newBytes, 0, newBytes.length); 76 if (resolve) { 77 resolveClass(c); 78 } 79 return c; 80 } 81 82 static void replaceBytes(byte[] bytes, byte[] find, byte[] replacement) { 83 for (int index = 0; index < bytes.length - find.length; index++) { 84 if (matches(bytes, index, find)) { 85 replace(bytes, index, replacement); 86 } 87 } 88 } 89 90 private static void replace(byte[] bytes, int startIndex, byte[] replacement) { 91 for (int index = 0; index < replacement.length; index++) { 92 bytes[startIndex + index] = replacement[index]; 93 } 94 } 95 96 private static boolean matches(byte[] bytes, int startIndex, byte[] matching) { 97 for (int i = 0; i < matching.length; i++) { 98 if (bytes[startIndex + i] != matching[i]) { 99 return false; 100 } 101 } 102 return true; 103 } 104 105 private static byte[] readTestClassBytes() { 106 try { 107 String classFileName = "jdk/jfr/event/oldobject/TestClassLoader$TestClass0000000.class"; 108 InputStream is = TestClassLoader.class.getClassLoader().getResourceAsStream(classFileName); 109 if (is == null) { 110 throw new RuntimeException("Culd not find class file " + classFileName); 111 } 112 byte[] b = is.readAllBytes(); 113 is.close(); 114 return b; 115 } catch (IOException ioe) { 116 ioe.printStackTrace(); 117 throw new RuntimeException(ioe); 118 } 119 } 120 }