1 /* 2 * Copyright (c) 2015, 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. 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 package jdk.test.lib.classloader; 24 25 import java.io.*; 26 import java.util.*; 27 28 /** 29 * Classloader that generates classes on the fly. 30 * 31 * This classloader can load classes with name starting with 'Class'. It will 32 * use TemplateClass as template and will replace class name in the bytecode of 33 * template class. It can be used for example to detect memory leaks in class 34 * loading or to quickly fill Metaspace. 35 */ 36 class TemplateClass { 37 } 38 39 public class GeneratingClassLoader extends ClassLoader { 40 41 public synchronized Class loadClass(String name) throws ClassNotFoundException { 42 return loadClass(name, false); 43 } 44 45 public synchronized Class loadClass(String name, boolean resolve) 46 throws ClassNotFoundException { 47 Class c = findLoadedClass(name); 48 if (c != null) { 49 return c; 50 } 51 if (!name.startsWith(PREFIX)) { 52 return super.loadClass(name, resolve); 53 } 54 if (name.length() != templateClassName.length()) { 55 throw new ClassNotFoundException("Only can load classes with name.length() = " + getNameLength() + " got: '" + name + "' length: " + name.length()); 56 } 57 byte[] bytecode = getPatchedByteCode(name); 58 c = defineClass(name, bytecode, 0, bytecode.length); 59 if (resolve) { 60 resolveClass(c); 61 } 62 return c; 63 } 64 65 /** 66 * Create generating class loader that will use class file for given class 67 * from classpath as template. 68 */ 69 public GeneratingClassLoader(String templateClassName) { 70 this.templateClassName = templateClassName; 71 classPath = System.getProperty("java.class.path").split(File.pathSeparator); 72 try { 73 templateClassNameBytes = templateClassName.getBytes(encoding); 74 } catch (UnsupportedEncodingException e) { 75 throw new RuntimeException(e); 76 } 77 } 78 79 /** 80 * Create generating class loader that will use class file for 81 * nsk.share.classload.TemplateClass as template. 82 */ 83 public GeneratingClassLoader() { 84 this(TemplateClass.class.getName()); 85 } 86 87 public int getNameLength() { 88 return templateClassName.length(); 89 } 90 91 String getPrefix() { 92 return PREFIX; 93 } 94 95 public String getClassName(int number) { 96 StringBuffer sb = new StringBuffer(); 97 sb.append(PREFIX); 98 sb.append(number); 99 int n = templateClassName.length() - sb.length(); 100 for (int i = 0; i < n; ++i) { 101 sb.append("_"); 102 } 103 return sb.toString(); 104 } 105 106 private byte[] getPatchedByteCode(String name) throws ClassNotFoundException { 107 try { 108 byte[] bytecode = getByteCode(); 109 String fname = name.replace(".", File.separator); 110 byte[] replaceBytes = fname.getBytes(encoding); 111 for (int offset : offsets) { 112 for (int i = 0; i < replaceBytes.length; ++i) { 113 bytecode[offset + i] = replaceBytes[i]; 114 } 115 } 116 return bytecode; 117 } catch (UnsupportedEncodingException e) { 118 throw new RuntimeException(e); 119 } 120 } 121 122 private byte[] getByteCode() throws ClassNotFoundException { 123 if (bytecode == null) { 124 readByteCode(); 125 } 126 if (offsets == null) { 127 getOffsets(bytecode); 128 if (offsets == null) { 129 throw new RuntimeException("Class name not found in template class file"); 130 } 131 } 132 return (byte[]) bytecode.clone(); 133 } 134 135 private void readByteCode() throws ClassNotFoundException { 136 String fname = templateClassName.replace(".", File.separator) + ".class"; 137 File target = null; 138 for (int i = 0; i < classPath.length; ++i) { 139 target = new File(classPath[i] + File.separator + fname); 140 if (target.exists()) { 141 break; 142 } 143 } 144 145 if (target == null || !target.exists()) { 146 throw new ClassNotFoundException("File not found: " + target); 147 } 148 try { 149 bytecode = ClassLoadUtils.readFile(target); 150 } catch (IOException e) { 151 throw new ClassNotFoundException(templateClassName, e); 152 } 153 } 154 155 private void getOffsets(byte[] bytecode) { 156 List<Integer> offsets = new ArrayList<Integer>(); 157 if (this.offsets == null) { 158 String pname = templateClassName.replace(".", "/"); 159 try { 160 byte[] pnameb = pname.getBytes(encoding); 161 int i = 0; 162 while (true) { 163 while (i < bytecode.length) { 164 int j = 0; 165 while (j < pnameb.length && bytecode[i + j] == pnameb[j]) { 166 ++j; 167 } 168 if (j == pnameb.length) { 169 break; 170 } 171 i++; 172 } 173 if (i == bytecode.length) { 174 break; 175 } 176 offsets.add(new Integer(i)); 177 i++; 178 } 179 } catch (UnsupportedEncodingException e) { 180 throw new RuntimeException(e); 181 } 182 this.offsets = new int[offsets.size()]; 183 for (int i = 0; i < offsets.size(); ++i) { 184 this.offsets[i] = offsets.get(i).intValue(); 185 } 186 } 187 } 188 189 public static final String DEFAULT_CLASSNAME = TemplateClass.class.getName(); 190 static final String PREFIX = "Class"; 191 192 private final String[] classPath; 193 private byte[] bytecode; 194 private int[] offsets; 195 private final String encoding = "UTF8"; 196 private final String templateClassName; 197 private final byte[] templateClassNameBytes; 198 }