1 /*
   2  * Copyright (c) 1997, 2017, 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 com.sun.xml.internal.bind.v2.runtime.reflect.opt;
  27 
  28 import java.lang.reflect.InvocationTargetException;
  29 import java.lang.reflect.Method;
  30 import java.lang.ref.WeakReference;
  31 import java.security.AccessController;
  32 import java.security.PrivilegedAction;
  33 import java.util.concurrent.locks.Lock;
  34 import java.util.concurrent.locks.ReentrantReadWriteLock;
  35 import java.util.HashMap;
  36 import java.util.Map;
  37 import java.util.WeakHashMap;
  38 import java.util.logging.Level;
  39 import java.util.logging.Logger;
  40 
  41 import com.sun.xml.internal.bind.Util;
  42 import com.sun.xml.internal.bind.v2.runtime.reflect.Accessor;
  43 import java.lang.reflect.Field;
  44 import java.security.CodeSource;
  45 import java.security.PrivilegedActionException;
  46 import java.security.PrivilegedExceptionAction;
  47 import java.security.ProtectionDomain;
  48 
  49 /**
  50  * A {@link ClassLoader} used to "inject" optimized accessor classes
  51  * into the VM.
  52  *
  53  * <p>
  54  * Its parent class loader needs to be set to the one that can see the user
  55  * class.
  56  *
  57  * @author Kohsuke Kawaguchi
  58  */
  59 final class Injector {
  60 
  61     /**
  62      * {@link Injector}s keyed by their parent {@link ClassLoader}.
  63      *
  64      * We only need one injector per one user class loader.
  65      */
  66     private static final ReentrantReadWriteLock irwl = new ReentrantReadWriteLock();
  67     private static final Lock ir = irwl.readLock();
  68     private static final Lock iw = irwl.writeLock();
  69     private static final Map<ClassLoader, WeakReference<Injector>> injectors =
  70             new WeakHashMap<ClassLoader, WeakReference<Injector>>();
  71     private static final Logger logger = Util.getClassLogger();
  72 
  73     /**
  74      * Injects a new class into the given class loader.
  75      *
  76      * @return null
  77      *      if it fails to inject.
  78      */
  79     static Class inject(ClassLoader cl, String className, byte[] image) {
  80         Injector injector = get(cl);
  81         if (injector != null) {
  82             return injector.inject(className, image);
  83         } else {
  84             return null;
  85         }
  86     }
  87 
  88     /**
  89      * Returns the already injected class, or null.
  90      */
  91     static Class find(ClassLoader cl, String className) {
  92         Injector injector = get(cl);
  93         if (injector != null) {
  94             return injector.find(className);
  95         } else {
  96             return null;
  97         }
  98     }
  99 
 100     /**
 101      * Gets or creates an {@link Injector} for the given class loader.
 102      *
 103      * @return null
 104      *      if it fails.
 105      */
 106     private static Injector get(ClassLoader cl) {
 107         Injector injector = null;
 108         WeakReference<Injector> wr;
 109         ir.lock();
 110         try {
 111             wr = injectors.get(cl);
 112         } finally {
 113             ir.unlock();
 114         }
 115         if (wr != null) {
 116             injector = wr.get();
 117         }
 118         if (injector == null) {
 119             try {
 120                 wr = new WeakReference<Injector>(injector = new Injector(cl));
 121                 iw.lock();
 122                 try {
 123                     if (!injectors.containsKey(cl)) {
 124                         injectors.put(cl, wr);
 125                     }
 126                 } finally {
 127                     iw.unlock();
 128                 }
 129             } catch (SecurityException e) {
 130                 logger.log(Level.FINE, "Unable to set up a back-door for the injector", e);
 131                 return null;
 132             }
 133         }
 134         return injector;
 135     }
 136     /**
 137      * Injected classes keyed by their names.
 138      */
 139     private final Map<String, Class> classes = new HashMap<>();
 140     private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
 141     private final Lock r = rwl.readLock();
 142     private final Lock w = rwl.writeLock();
 143     private final ClassLoader parent;
 144     /**
 145      * True if this injector is capable of injecting accessors.
 146      * False otherwise, which happens if this classloader can't see {@link Accessor}.
 147      */
 148     private final boolean loadable;
 149     private static Method defineClass;
 150     private static Method resolveClass;
 151     private static Method findLoadedClass;
 152     private static Object U;
 153 
 154     static {
 155         try {
 156             Method[] m = AccessController.doPrivileged(
 157                     new PrivilegedAction<Method[]>() {
 158                 @Override
 159                 public Method[] run() {
 160                     return new Method[]{
 161                         getMethod(ClassLoader.class, "defineClass", String.class, byte[].class, Integer.TYPE, Integer.TYPE),
 162                         getMethod(ClassLoader.class, "resolveClass", Class.class),
 163                         getMethod(ClassLoader.class, "findLoadedClass", String.class)
 164                     };
 165                 }
 166             }
 167             );
 168             defineClass = m[0];
 169             resolveClass = m[1];
 170             findLoadedClass = m[2];
 171         } catch (Throwable t) {
 172             try {
 173                 U = AccessController.doPrivileged(new PrivilegedExceptionAction() {
 174                     @Override
 175                     public Object run() throws Exception {
 176                         Class u = Class.forName("sun.misc.Unsafe");
 177                         Field theUnsafe = u.getDeclaredField("theUnsafe");
 178                         theUnsafe.setAccessible(true);
 179                         return theUnsafe.get(null);
 180                     }
 181                 });
 182                 defineClass = AccessController.doPrivileged(new PrivilegedExceptionAction<Method>() {
 183                     @Override
 184                     public Method run() throws Exception {
 185                         try {
 186                             return U.getClass().getMethod("defineClass",
 187                                     new Class[]{String.class,
 188                                         byte[].class,
 189                                         Integer.TYPE,
 190                                         Integer.TYPE,
 191                                         ClassLoader.class,
 192                                         ProtectionDomain.class});
 193                         } catch (NoSuchMethodException | SecurityException ex) {
 194                             throw ex;
 195                         }
 196                     }
 197                 });
 198             } catch (SecurityException | PrivilegedActionException ex) {
 199                 Logger.getLogger(Injector.class.getName()).log(Level.SEVERE, null, ex);
 200             }
 201         }
 202     }
 203 
 204     private static Method getMethod(final Class<?> c, final String methodname, final Class<?>... params) {
 205         try {
 206             Method m = c.getDeclaredMethod(methodname, params);
 207             m.setAccessible(true);
 208             return m;
 209         } catch (NoSuchMethodException e) {
 210             throw new NoSuchMethodError(e.getMessage());
 211         }
 212     }
 213 
 214     private Injector(ClassLoader parent) {
 215         this.parent = parent;
 216         assert parent != null;
 217 
 218         boolean loadableCheck = false;
 219 
 220         try {
 221             loadableCheck = parent.loadClass(Accessor.class.getName()) == Accessor.class;
 222         } catch (ClassNotFoundException e) {
 223             // not loadable
 224         }
 225 
 226         this.loadable = loadableCheck;
 227     }
 228 
 229     @SuppressWarnings("LockAcquiredButNotSafelyReleased")
 230     private Class inject(String className, byte[] image) {
 231         if (!loadable) // this injector cannot inject anything
 232         {
 233             return null;
 234         }
 235 
 236         boolean wlocked = false;
 237         boolean rlocked = false;
 238         try {
 239 
 240             r.lock();
 241             rlocked = true;
 242 
 243             Class c = classes.get(className);
 244 
 245             // Unlock now during the findLoadedClass process to avoid
 246             // deadlocks
 247             r.unlock();
 248             rlocked = false;
 249 
 250             //find loaded class from classloader
 251             if (c == null && findLoadedClass != null) {
 252 
 253                 try {
 254                     c = (Class) findLoadedClass.invoke(parent, className.replace('/', '.'));
 255                 } catch (IllegalArgumentException | IllegalAccessException e) {
 256                     logger.log(Level.FINE, "Unable to find " + className, e);
 257                 } catch (InvocationTargetException e) {
 258                     Throwable t = e.getTargetException();
 259                     logger.log(Level.FINE, "Unable to find " + className, t);
 260                 }
 261 
 262                 if (c != null) {
 263 
 264                     w.lock();
 265                     wlocked = true;
 266 
 267                     classes.put(className, c);
 268 
 269                     w.unlock();
 270                     wlocked = false;
 271 
 272                     return c;
 273                 }
 274             }
 275 
 276             if (c == null) {
 277 
 278                 r.lock();
 279                 rlocked = true;
 280 
 281                 c = classes.get(className);
 282 
 283                 // Unlock now during the define/resolve process to avoid
 284                 // deadlocks
 285                 r.unlock();
 286                 rlocked = false;
 287 
 288                 if (c == null) {
 289 
 290                     // we need to inject a class into the
 291                     try {
 292                         if (resolveClass != null) {
 293                             c = (Class) defineClass.invoke(parent, className.replace('/', '.'), image, 0, image.length);
 294                             resolveClass.invoke(parent, c);
 295                         } else {
 296                             c = (Class) defineClass.invoke(U, className.replace('/', '.'), image, 0, image.length, parent, Injector.class.getProtectionDomain());
 297                         }
 298                     } catch (IllegalAccessException  e) {
 299                         logger.log(Level.FINE, "Unable to inject " + className, e);
 300                         return null;
 301                     } catch (InvocationTargetException e) {
 302                         Throwable t = e.getTargetException();
 303                         if (t instanceof LinkageError) {
 304                             logger.log(Level.FINE, "duplicate class definition bug occured? Please report this : " + className, t);
 305                         } else {
 306                             logger.log(Level.FINE, "Unable to inject " + className, t);
 307                         }
 308                         return null;
 309                     } catch (SecurityException e) {
 310                         logger.log(Level.FINE, "Unable to inject " + className, e);
 311                         return null;
 312                     } catch (LinkageError e) {
 313                         logger.log(Level.FINE, "Unable to inject " + className, e);
 314                         return null;
 315                     }
 316 
 317                     w.lock();
 318                     wlocked = true;
 319 
 320                     // During the time we were unlocked, we could have tried to
 321                     // load the class from more than one thread. Check now to see
 322                     // if someone else beat us to registering this class
 323                     if (!classes.containsKey(className)) {
 324                         classes.put(className, c);
 325                     }
 326 
 327                     w.unlock();
 328                     wlocked = false;
 329                 }
 330             }
 331             return c;
 332         } finally {
 333             if (rlocked) {
 334                 r.unlock();
 335             }
 336             if (wlocked) {
 337                 w.unlock();
 338             }
 339         }
 340     }
 341 
 342     private Class find(String className) {
 343         r.lock();
 344         try {
 345             return classes.get(className);
 346         } finally {
 347             r.unlock();
 348         }
 349     }
 350 }