1 /* 2 * Copyright (c) 2018, 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 import java.io.ByteArrayOutputStream; 33 34 /* 35 * A special class loader that will, for our test class, make sure that each 36 * load will become a unique class 37 */ 38 public final class TestClassLoader extends ClassLoader { 39 40 public static final class TestClass0000000 { 41 public static final byte[] oneByte = new byte[1]; 42 } 43 44 static byte[] classByteCode = readTestClassBytes(); 45 private static int classIdCounter; 46 47 TestClassLoader() { 48 super(TestClassLoader.class.getClassLoader()); 49 } 50 51 public List<Class<?>> loadClasses(int count) throws Exception { 52 List<Class<?>> classes = new ArrayList<>(); 53 for (int i = 0; i < count; i++) { 54 String className = "jdk.jfr.event.oldobject.TestClassLoader$"; 55 className += "TestClass" + String.format("%07d", classIdCounter++); 56 Class<?> clazz = Class.forName(className, true, this); 57 classes.add(clazz); 58 } 59 return classes; 60 } 61 62 @Override 63 protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { 64 // If not loading the test class, just go on with the normal class loader 65 if (!name.contains("TestClass")) { 66 return super.loadClass(name, resolve); 67 } 68 String[] classNameParts = name.split("\\$"); 69 String newName = classNameParts[1]; 70 String oldName = "TestClass0000000"; 71 if (oldName.length() != newName.length()) { 72 throw new AssertionError("String lengths don't match. Unable to replace class name"); 73 } 74 byte[] newBytes = classByteCode.clone(); 75 replaceBytes(newBytes, oldName.getBytes(), newName.getBytes()); 76 Class<?> c = defineClass(name, newBytes, 0, newBytes.length); 77 if (resolve) { 78 resolveClass(c); 79 } 80 return c; 81 } 82 83 static void replaceBytes(byte[] bytes, byte[] find, byte[] replacement) { 84 for (int index = 0; index < bytes.length - find.length; index++) { 85 if (matches(bytes, index, find)) { 86 replace(bytes, index, replacement); 87 } 88 } 89 } 90 91 private static void replace(byte[] bytes, int startIndex, byte[] replacement) { 92 for (int index = 0; index < replacement.length; index++) { 93 bytes[startIndex + index] = replacement[index]; 94 } 95 } 96 97 private static boolean matches(byte[] bytes, int startIndex, byte[] matching) { 98 for (int i = 0; i < matching.length; i++) { 99 if (bytes[startIndex + i] != matching[i]) { 100 return false; 101 } 102 } 103 return true; 104 } 105 106 private static byte[] readTestClassBytes() { 107 try { 108 String classFileName = "jdk/jfr/event/oldobject/TestClassLoader$TestClass0000000.class"; 109 InputStream is = TestClassLoader.class.getClassLoader().getResourceAsStream(classFileName); 110 if (is == null) { 111 throw new RuntimeException("Culd not find class file " + classFileName); 112 } 113 //byte[] b;= is.readAllBytes(); 114 //is.read(b); 115 ByteArrayOutputStream os = new ByteArrayOutputStream(); 116 byte[] buffer = new byte[0xFFFF]; 117 for (int len = is.read(buffer); len != -1; len = is.read(buffer)) { 118 os.write(buffer, 0, len); 119 } 120 is.close(); 121 return os.toByteArray(); 122 } catch (IOException ioe) { 123 ioe.printStackTrace(); 124 throw new RuntimeException(ioe); 125 } 126 } 127 }