1 /* 2 * Copyright (c) 2007, 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 24 package nsk.share.classload; 25 26 import java.io.*; 27 import java.util.*; 28 import nsk.share.*; 29 30 /** 31 * Classloader that generates classes on the fly. 32 * 33 * This classloader can load classes with name starting with 'Class'. 34 * It will use nsk.share.classload.TemplateClass as template and will 35 * replace class name in the bytecode of template class. It can be used 36 * for example to detect memory leaks in class loading or to quickly 37 * fill PermGen. 38 */ 39 public class GeneratingClassLoader extends ClassLoader { 40 public static final String DEFAULT_CLASSNAME = TemplateClass.class.getName(); 41 public static final String PREFIX = "Class"; 42 43 private final String [] classPath; 44 private byte[] bytecode; 45 private int[] offsets; 46 private final String encoding = "UTF8"; 47 private final String templateClassName; 48 private final byte[] templateClassNameBytes; 49 50 /** 51 * Create generating class loader that will use class file 52 * for given class from classpath as template. 53 */ GeneratingClassLoader(String templateClassName)54 public GeneratingClassLoader(String templateClassName) { 55 this.templateClassName = templateClassName; 56 classPath = System.getProperty("java.class.path").split(File.pathSeparator); 57 try { 58 templateClassNameBytes = templateClassName.getBytes(encoding); 59 } catch (UnsupportedEncodingException e) { 60 throw new TestBug(e); 61 } 62 } 63 64 /** 65 * Create generating class loader that will use class file 66 * for nsk.share.classload.TemplateClass as template. 67 */ GeneratingClassLoader()68 public GeneratingClassLoader() { 69 this("nsk.share.classload.TemplateClass"); 70 } 71 getNameLength()72 public int getNameLength() { 73 return templateClassName.length(); 74 } 75 getPrefix()76 public String getPrefix() { 77 return PREFIX; 78 } 79 getClassName(int number)80 public String getClassName(int number) { 81 StringBuffer sb = new StringBuffer(); 82 sb.append(PREFIX); 83 sb.append(number); 84 int n = templateClassName.length() - sb.length(); 85 for (int i = 0; i < n; ++i) 86 sb.append("_"); 87 return sb.toString(); 88 } 89 loadClass(String name)90 public synchronized Class loadClass(String name) throws ClassNotFoundException { 91 return loadClass(name, false); 92 } 93 loadClass(String name, boolean resolve)94 public synchronized Class loadClass(String name, boolean resolve) 95 throws ClassNotFoundException { 96 Class c = findLoadedClass(name); 97 if (c != null) 98 return c; 99 if (!name.startsWith(PREFIX)) 100 return super.loadClass(name, resolve); 101 if (name.length() != templateClassName.length()) 102 throw new ClassNotFoundException("Only can load classes with name.length() = " + getNameLength() + " got: '" + name + "' length: " + name.length()); 103 byte[] bytecode = getPatchedByteCode(name); 104 c = defineClass(name, bytecode, 0, bytecode.length); 105 if (resolve) 106 resolveClass(c); 107 return c; 108 } 109 getPatchedByteCode(String name)110 private byte[] getPatchedByteCode(String name) throws ClassNotFoundException { 111 try { 112 byte[] bytecode = getByteCode(); 113 String fname = name.replace(".", File.separator); 114 byte[] replaceBytes = fname.getBytes(encoding); 115 for (int offset : offsets) { 116 for (int i = 0; i < replaceBytes.length; ++i) 117 bytecode[offset + i] = replaceBytes[i]; 118 } 119 return bytecode; 120 } catch (UnsupportedEncodingException e) { 121 throw new TestBug(e); 122 } catch (IOException e) { 123 throw new TestBug(e); 124 } 125 } 126 getByteCode()127 private byte[] getByteCode() throws ClassNotFoundException { 128 if (bytecode == null) 129 readByteCode(); 130 if (offsets == null) { 131 getOffsets(bytecode); 132 if (offsets == null) 133 throw new TestBug("Class name not found in template class file"); 134 } 135 return (byte[]) bytecode.clone(); 136 } 137 readByteCode()138 private void readByteCode() throws ClassNotFoundException { 139 String fname = templateClassName.replace(".", File.separator) + ".class"; 140 File target = null; 141 for (int i = 0; i < classPath.length; ++i) { 142 target = new File(classPath[i] + File.separator + fname); 143 if (target.exists()) 144 break; 145 } 146 147 if (target == null || !target.exists()) 148 throw new ClassNotFoundException("File not found: " + target); 149 try { 150 bytecode = FileUtils.readFile(target); 151 } catch (IOException e) { 152 throw new ClassNotFoundException(templateClassName, e); 153 } 154 } 155 getOffsets(byte[] bytecode)156 private void getOffsets(byte[] bytecode) { 157 List<Integer> offsets = new ArrayList<Integer>(); 158 if (this.offsets == null) { 159 String pname = templateClassName.replace(".", "/"); 160 try { 161 byte[] pnameb = pname.getBytes(encoding); 162 int i = 0; 163 while (true) { 164 while (i < bytecode.length) { 165 int j = 0; 166 while (j < pnameb.length && bytecode[i + j] == pnameb[j]) 167 ++j; 168 if (j == pnameb.length) 169 break; 170 i++; 171 } 172 if (i == bytecode.length) 173 break; 174 offsets.add(new Integer(i)); 175 i++; 176 } 177 } catch (UnsupportedEncodingException e) { 178 throw new TestBug(e); 179 } 180 this.offsets = new int[offsets.size()]; 181 for (int i = 0; i < offsets.size(); ++i) 182 this.offsets[i] = offsets.get(i).intValue(); 183 } 184 } 185 } 186