1 /*
   2  * Copyright (c) 1996, 2011, 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 java.io;
  27 
  28 import java.lang.ref.Reference;
  29 import java.lang.ref.ReferenceQueue;
  30 import java.lang.ref.SoftReference;
  31 import java.lang.ref.WeakReference;
  32 import java.lang.reflect.Constructor;
  33 import java.lang.reflect.Field;
  34 import java.lang.reflect.InvocationTargetException;
  35 import java.lang.reflect.Member;
  36 import java.lang.reflect.Method;
  37 import java.lang.reflect.Modifier;
  38 import java.lang.reflect.Proxy;
  39 import java.security.AccessController;
  40 import java.security.MessageDigest;
  41 import java.security.NoSuchAlgorithmException;
  42 import java.security.PrivilegedAction;
  43 import java.util.ArrayList;
  44 import java.util.Arrays;
  45 import java.util.Collections;
  46 import java.util.Comparator;
  47 import java.util.HashSet;
  48 import java.util.Set;
  49 import java.util.concurrent.ConcurrentHashMap;
  50 import java.util.concurrent.ConcurrentMap;
  51 import sun.misc.Unsafe;
  52 import sun.reflect.ReflectionFactory;
  53 
  54 /**
  55  * Serialization's descriptor for classes.  It contains the name and
  56  * serialVersionUID of the class.  The ObjectStreamClass for a specific class
  57  * loaded in this Java VM can be found/created using the lookup method.
  58  *
  59  * <p>The algorithm to compute the SerialVersionUID is described in
  60  * <a href="../../../platform/serialization/spec/class.html#4100">Object
  61  * Serialization Specification, Section 4.6, Stream Unique Identifiers</a>.
  62  *
  63  * @author      Mike Warres
  64  * @author      Roger Riggs
  65  * @see ObjectStreamField
  66  * @see <a href="../../../platform/serialization/spec/class.html">Object Serialization Specification, Section 4, Class Descriptors</a>
  67  * @since   JDK1.1
  68  */
  69 public class ObjectStreamClass implements Serializable {
  70 
  71     /** serialPersistentFields value indicating no serializable fields */
  72     public static final ObjectStreamField[] NO_FIELDS =
  73         new ObjectStreamField[0];
  74 
  75     private static final long serialVersionUID = -6120832682080437368L;
  76     private static final ObjectStreamField[] serialPersistentFields =
  77         NO_FIELDS;
  78 
  79     /** reflection factory for obtaining serialization constructors */
  80     private static final ReflectionFactory reflFactory =
  81         AccessController.doPrivileged(
  82             new ReflectionFactory.GetReflectionFactoryAction());
  83 
  84     private static class Caches {
  85         /** cache mapping local classes -> descriptors */
  86         static final ConcurrentMap<WeakClassKey,Reference<?>> localDescs =
  87             new ConcurrentHashMap<>();
  88 
  89         /** cache mapping field group/local desc pairs -> field reflectors */
  90         static final ConcurrentMap<FieldReflectorKey,Reference<?>> reflectors =
  91             new ConcurrentHashMap<>();
  92 
  93         /** queue for WeakReferences to local classes */
  94         private static final ReferenceQueue<Class<?>> localDescsQueue =
  95             new ReferenceQueue<>();
  96         /** queue for WeakReferences to field reflectors keys */
  97         private static final ReferenceQueue<Class<?>> reflectorsQueue =
  98             new ReferenceQueue<>();
  99     }
 100 
 101     /** class associated with this descriptor (if any) */
 102     private Class<?> cl;
 103     /** name of class represented by this descriptor */
 104     private String name;
 105     /** serialVersionUID of represented class (null if not computed yet) */
 106     private volatile Long suid;
 107 
 108     /** true if represents dynamic proxy class */
 109     private boolean isProxy;
 110     /** true if represents enum type */
 111     private boolean isEnum;
 112     /** true if represented class implements Serializable */
 113     private boolean serializable;
 114     /** true if represented class implements Externalizable */
 115     private boolean externalizable;
 116     /** true if desc has data written by class-defined writeObject method */
 117     private boolean hasWriteObjectData;
 118     /**
 119      * true if desc has externalizable data written in block data format; this
 120      * must be true by default to accommodate ObjectInputStream subclasses which
 121      * override readClassDescriptor() to return class descriptors obtained from
 122      * ObjectStreamClass.lookup() (see 4461737)
 123      */
 124     private boolean hasBlockExternalData = true;
 125 
 126     /** exception (if any) thrown while attempting to resolve class */
 127     private ClassNotFoundException resolveEx;
 128     /** exception (if any) to throw if non-enum deserialization attempted */
 129     private InvalidClassException deserializeEx;
 130     /** exception (if any) to throw if non-enum serialization attempted */
 131     private InvalidClassException serializeEx;
 132     /** exception (if any) to throw if default serialization attempted */
 133     private InvalidClassException defaultSerializeEx;
 134 
 135     /** serializable fields */
 136     private ObjectStreamField[] fields;
 137     /** aggregate marshalled size of primitive fields */
 138     private int primDataSize;
 139     /** number of non-primitive fields */
 140     private int numObjFields;
 141     /** reflector for setting/getting serializable field values */
 142     private FieldReflector fieldRefl;
 143     /** data layout of serialized objects described by this class desc */
 144     private volatile ClassDataSlot[] dataLayout;
 145 
 146     /** serialization-appropriate constructor, or null if none */
 147     private Constructor<?> cons;
 148     /** class-defined writeObject method, or null if none */
 149     private Method writeObjectMethod;
 150     /** class-defined readObject method, or null if none */
 151     private Method readObjectMethod;
 152     /** class-defined readObjectNoData method, or null if none */
 153     private Method readObjectNoDataMethod;
 154     /** class-defined writeReplace method, or null if none */
 155     private Method writeReplaceMethod;
 156     /** class-defined readResolve method, or null if none */
 157     private Method readResolveMethod;
 158 
 159     /** local class descriptor for represented class (may point to self) */
 160     private ObjectStreamClass localDesc;
 161     /** superclass descriptor appearing in stream */
 162     private ObjectStreamClass superDesc;
 163 
 164     /**
 165      * Initializes native code.
 166      */
 167     private static native void initNative();
 168     static {
 169         initNative();
 170     }
 171 
 172     /**
 173      * Find the descriptor for a class that can be serialized.  Creates an
 174      * ObjectStreamClass instance if one does not exist yet for class. Null is
 175      * returned if the specified class does not implement java.io.Serializable
 176      * or java.io.Externalizable.
 177      *
 178      * @param   cl class for which to get the descriptor
 179      * @return  the class descriptor for the specified class
 180      */
 181     public static ObjectStreamClass lookup(Class<?> cl) {
 182         return lookup(cl, false);
 183     }
 184 
 185     /**
 186      * Returns the descriptor for any class, regardless of whether it
 187      * implements {@link Serializable}.
 188      *
 189      * @param        cl class for which to get the descriptor
 190      * @return       the class descriptor for the specified class
 191      * @since 1.6
 192      */
 193     public static ObjectStreamClass lookupAny(Class<?> cl) {
 194         return lookup(cl, true);
 195     }
 196 
 197     /**
 198      * Returns the name of the class described by this descriptor.
 199      * This method returns the name of the class in the format that
 200      * is used by the {@link Class#getName} method.
 201      *
 202      * @return a string representing the name of the class
 203      */
 204     public String getName() {
 205         return name;
 206     }
 207 
 208     /**
 209      * Return the serialVersionUID for this class.  The serialVersionUID
 210      * defines a set of classes all with the same name that have evolved from a
 211      * common root class and agree to be serialized and deserialized using a
 212      * common format.  NonSerializable classes have a serialVersionUID of 0L.
 213      *
 214      * @return  the SUID of the class described by this descriptor
 215      */
 216     public long getSerialVersionUID() {
 217         // REMIND: synchronize instead of relying on volatile?
 218         if (suid == null) {
 219             suid = AccessController.doPrivileged(
 220                 new PrivilegedAction<Long>() {
 221                     public Long run() {
 222                         return computeDefaultSUID(cl);
 223                     }
 224                 }
 225             );
 226         }
 227         return suid.longValue();
 228     }
 229 
 230     /**
 231      * Return the class in the local VM that this version is mapped to.  Null
 232      * is returned if there is no corresponding local class.
 233      *
 234      * @return  the <code>Class</code> instance that this descriptor represents
 235      */
 236     public Class<?> forClass() {
 237         return cl;
 238     }
 239 
 240     /**
 241      * Return an array of the fields of this serializable class.
 242      *
 243      * @return  an array containing an element for each persistent field of
 244      *          this class. Returns an array of length zero if there are no
 245      *          fields.
 246      * @since 1.2
 247      */
 248     public ObjectStreamField[] getFields() {
 249         return getFields(true);
 250     }
 251 
 252     /**
 253      * Get the field of this class by name.
 254      *
 255      * @param   name the name of the data field to look for
 256      * @return  The ObjectStreamField object of the named field or null if
 257      *          there is no such named field.
 258      */
 259     public ObjectStreamField getField(String name) {
 260         return getField(name, null);
 261     }
 262 
 263     /**
 264      * Return a string describing this ObjectStreamClass.
 265      */
 266     public String toString() {
 267         return name + ": static final long serialVersionUID = " +
 268             getSerialVersionUID() + "L;";
 269     }
 270 
 271     /**
 272      * Looks up and returns class descriptor for given class, or null if class
 273      * is non-serializable and "all" is set to false.
 274      *
 275      * @param   cl class to look up
 276      * @param   all if true, return descriptors for all classes; if false, only
 277      *          return descriptors for serializable classes
 278      */
 279     static ObjectStreamClass lookup(Class<?> cl, boolean all) {
 280         if (!(all || Serializable.class.isAssignableFrom(cl))) {
 281             return null;
 282         }
 283         processQueue(Caches.localDescsQueue, Caches.localDescs);
 284         WeakClassKey key = new WeakClassKey(cl, Caches.localDescsQueue);
 285         Reference<?> ref = Caches.localDescs.get(key);
 286         Object entry = null;
 287         if (ref != null) {
 288             entry = ref.get();
 289         }
 290         EntryFuture future = null;
 291         if (entry == null) {
 292             EntryFuture newEntry = new EntryFuture();
 293             Reference<?> newRef = new SoftReference<>(newEntry);
 294             do {
 295                 if (ref != null) {
 296                     Caches.localDescs.remove(key, ref);
 297                 }
 298                 ref = Caches.localDescs.putIfAbsent(key, newRef);
 299                 if (ref != null) {
 300                     entry = ref.get();
 301                 }
 302             } while (ref != null && entry == null);
 303             if (entry == null) {
 304                 future = newEntry;
 305             }
 306         }
 307 
 308         if (entry instanceof ObjectStreamClass) {  // check common case first
 309             return (ObjectStreamClass) entry;
 310         }
 311         if (entry instanceof EntryFuture) {
 312             future = (EntryFuture) entry;
 313             if (future.getOwner() == Thread.currentThread()) {
 314                 /*
 315                  * Handle nested call situation described by 4803747: waiting
 316                  * for future value to be set by a lookup() call further up the
 317                  * stack will result in deadlock, so calculate and set the
 318                  * future value here instead.
 319                  */
 320                 entry = null;
 321             } else {
 322                 entry = future.get();
 323             }
 324         }
 325         if (entry == null) {
 326             try {
 327                 entry = new ObjectStreamClass(cl);
 328             } catch (Throwable th) {
 329                 entry = th;
 330             }
 331             if (future.set(entry)) {
 332                 Caches.localDescs.put(key, new SoftReference<Object>(entry));
 333             } else {
 334                 // nested lookup call already set future
 335                 entry = future.get();
 336             }
 337         }
 338 
 339         if (entry instanceof ObjectStreamClass) {
 340             return (ObjectStreamClass) entry;
 341         } else if (entry instanceof RuntimeException) {
 342             throw (RuntimeException) entry;
 343         } else if (entry instanceof Error) {
 344             throw (Error) entry;
 345         } else {
 346             throw new InternalError("unexpected entry: " + entry);
 347         }
 348     }
 349 
 350     /**
 351      * Placeholder used in class descriptor and field reflector lookup tables
 352      * for an entry in the process of being initialized.  (Internal) callers
 353      * which receive an EntryFuture belonging to another thread as the result
 354      * of a lookup should call the get() method of the EntryFuture; this will
 355      * return the actual entry once it is ready for use and has been set().  To
 356      * conserve objects, EntryFutures synchronize on themselves.
 357      */
 358     private static class EntryFuture {
 359 
 360         private static final Object unset = new Object();
 361         private final Thread owner = Thread.currentThread();
 362         private Object entry = unset;
 363 
 364         /**
 365          * Attempts to set the value contained by this EntryFuture.  If the
 366          * EntryFuture's value has not been set already, then the value is
 367          * saved, any callers blocked in the get() method are notified, and
 368          * true is returned.  If the value has already been set, then no saving
 369          * or notification occurs, and false is returned.
 370          */
 371         synchronized boolean set(Object entry) {
 372             if (this.entry != unset) {
 373                 return false;
 374             }
 375             this.entry = entry;
 376             notifyAll();
 377             return true;
 378         }
 379 
 380         /**
 381          * Returns the value contained by this EntryFuture, blocking if
 382          * necessary until a value is set.
 383          */
 384         synchronized Object get() {
 385             boolean interrupted = false;
 386             while (entry == unset) {
 387                 try {
 388                     wait();
 389                 } catch (InterruptedException ex) {
 390                     interrupted = true;
 391                 }
 392             }
 393             if (interrupted) {
 394                 AccessController.doPrivileged(
 395                     new PrivilegedAction<Void>() {
 396                         public Void run() {
 397                             Thread.currentThread().interrupt();
 398                             return null;
 399                         }
 400                     }
 401                 );
 402             }
 403             return entry;
 404         }
 405 
 406         /**
 407          * Returns the thread that created this EntryFuture.
 408          */
 409         Thread getOwner() {
 410             return owner;
 411         }
 412     }
 413 
 414     /**
 415      * Creates local class descriptor representing given class.
 416      */
 417     private ObjectStreamClass(final Class<?> cl) {
 418         this.cl = cl;
 419         name = cl.getName();
 420         isProxy = Proxy.isProxyClass(cl);
 421         isEnum = Enum.class.isAssignableFrom(cl);
 422         serializable = Serializable.class.isAssignableFrom(cl);
 423         externalizable = Externalizable.class.isAssignableFrom(cl);
 424 
 425         Class<?> superCl = cl.getSuperclass();
 426         superDesc = (superCl != null) ? lookup(superCl, false) : null;
 427         localDesc = this;
 428 
 429         if (serializable) {
 430             AccessController.doPrivileged(new PrivilegedAction<Void>() {
 431                 public Void run() {
 432                     if (isEnum) {
 433                         suid = Long.valueOf(0);
 434                         fields = NO_FIELDS;
 435                         return null;
 436                     }
 437                     if (cl.isArray()) {
 438                         fields = NO_FIELDS;
 439                         return null;
 440                     }
 441 
 442                     suid = getDeclaredSUID(cl);
 443                     try {
 444                         fields = getSerialFields(cl);
 445                         computeFieldOffsets();
 446                     } catch (InvalidClassException e) {
 447                         serializeEx = deserializeEx = e;
 448                         fields = NO_FIELDS;
 449                     }
 450 
 451                     if (externalizable) {
 452                         cons = getExternalizableConstructor(cl);
 453                     } else {
 454                         cons = getSerializableConstructor(cl);
 455                         writeObjectMethod = getPrivateMethod(cl, "writeObject",
 456                             new Class<?>[] { ObjectOutputStream.class },
 457                             Void.TYPE);
 458                         readObjectMethod = getPrivateMethod(cl, "readObject",
 459                             new Class<?>[] { ObjectInputStream.class },
 460                             Void.TYPE);
 461                         readObjectNoDataMethod = getPrivateMethod(
 462                             cl, "readObjectNoData", null, Void.TYPE);
 463                         hasWriteObjectData = (writeObjectMethod != null);
 464                     }
 465                     writeReplaceMethod = getInheritableMethod(
 466                         cl, "writeReplace", null, Object.class);
 467                     readResolveMethod = getInheritableMethod(
 468                         cl, "readResolve", null, Object.class);
 469                     return null;
 470                 }
 471             });
 472         } else {
 473             suid = Long.valueOf(0);
 474             fields = NO_FIELDS;
 475         }
 476 
 477         try {
 478             fieldRefl = getReflector(fields, this);
 479         } catch (InvalidClassException ex) {
 480             // field mismatches impossible when matching local fields vs. self
 481             throw new InternalError(ex);
 482         }
 483 
 484         if (deserializeEx == null) {
 485             if (isEnum) {
 486                 deserializeEx = new InvalidClassException(name, "enum type");
 487             } else if (cons == null) {
 488                 deserializeEx = new InvalidClassException(
 489                     name, "no valid constructor");
 490             }
 491         }
 492         for (int i = 0; i < fields.length; i++) {
 493             if (fields[i].getField() == null) {
 494                 defaultSerializeEx = new InvalidClassException(
 495                     name, "unmatched serializable field(s) declared");
 496             }
 497         }
 498     }
 499 
 500     /**
 501      * Creates blank class descriptor which should be initialized via a
 502      * subsequent call to initProxy(), initNonProxy() or readNonProxy().
 503      */
 504     ObjectStreamClass() {
 505     }
 506 
 507     /**
 508      * Initializes class descriptor representing a proxy class.
 509      */
 510     void initProxy(Class<?> cl,
 511                    ClassNotFoundException resolveEx,
 512                    ObjectStreamClass superDesc)
 513         throws InvalidClassException
 514     {
 515         this.cl = cl;
 516         this.resolveEx = resolveEx;
 517         this.superDesc = superDesc;
 518         isProxy = true;
 519         serializable = true;
 520         suid = Long.valueOf(0);
 521         fields = NO_FIELDS;
 522 
 523         if (cl != null) {
 524             localDesc = lookup(cl, true);
 525             if (!localDesc.isProxy) {
 526                 throw new InvalidClassException(
 527                     "cannot bind proxy descriptor to a non-proxy class");
 528             }
 529             name = localDesc.name;
 530             externalizable = localDesc.externalizable;
 531             cons = localDesc.cons;
 532             writeReplaceMethod = localDesc.writeReplaceMethod;
 533             readResolveMethod = localDesc.readResolveMethod;
 534             deserializeEx = localDesc.deserializeEx;
 535         }
 536         fieldRefl = getReflector(fields, localDesc);
 537     }
 538 
 539     /**
 540      * Initializes class descriptor representing a non-proxy class.
 541      */
 542     void initNonProxy(ObjectStreamClass model,
 543                       Class<?> cl,
 544                       ClassNotFoundException resolveEx,
 545                       ObjectStreamClass superDesc)
 546         throws InvalidClassException
 547     {
 548         this.cl = cl;
 549         this.resolveEx = resolveEx;
 550         this.superDesc = superDesc;
 551         name = model.name;
 552         suid = Long.valueOf(model.getSerialVersionUID());
 553         isProxy = false;
 554         isEnum = model.isEnum;
 555         serializable = model.serializable;
 556         externalizable = model.externalizable;
 557         hasBlockExternalData = model.hasBlockExternalData;
 558         hasWriteObjectData = model.hasWriteObjectData;
 559         fields = model.fields;
 560         primDataSize = model.primDataSize;
 561         numObjFields = model.numObjFields;
 562 
 563         if (cl != null) {
 564             localDesc = lookup(cl, true);
 565             if (localDesc.isProxy) {
 566                 throw new InvalidClassException(
 567                     "cannot bind non-proxy descriptor to a proxy class");
 568             }
 569             if (isEnum != localDesc.isEnum) {
 570                 throw new InvalidClassException(isEnum ?
 571                     "cannot bind enum descriptor to a non-enum class" :
 572                     "cannot bind non-enum descriptor to an enum class");
 573             }
 574 
 575             if (serializable == localDesc.serializable &&
 576                 !cl.isArray() &&
 577                 suid.longValue() != localDesc.getSerialVersionUID())
 578             {
 579                 throw new InvalidClassException(localDesc.name,
 580                     "local class incompatible: " +
 581                     "stream classdesc serialVersionUID = " + suid +
 582                     ", local class serialVersionUID = " +
 583                     localDesc.getSerialVersionUID());
 584             }
 585 
 586             if (!classNamesEqual(name, localDesc.name)) {
 587                 throw new InvalidClassException(localDesc.name,
 588                     "local class name incompatible with stream class " +
 589                     "name \"" + name + "\"");
 590             }
 591 
 592             if (!isEnum) {
 593                 if ((serializable == localDesc.serializable) &&
 594                     (externalizable != localDesc.externalizable))
 595                 {
 596                     throw new InvalidClassException(localDesc.name,
 597                         "Serializable incompatible with Externalizable");
 598                 }
 599 
 600                 if ((serializable != localDesc.serializable) ||
 601                     (externalizable != localDesc.externalizable) ||
 602                     !(serializable || externalizable))
 603                 {
 604                     deserializeEx = new InvalidClassException(localDesc.name,
 605                         "class invalid for deserialization");
 606                 }
 607             }
 608 
 609             cons = localDesc.cons;
 610             writeObjectMethod = localDesc.writeObjectMethod;
 611             readObjectMethod = localDesc.readObjectMethod;
 612             readObjectNoDataMethod = localDesc.readObjectNoDataMethod;
 613             writeReplaceMethod = localDesc.writeReplaceMethod;
 614             readResolveMethod = localDesc.readResolveMethod;
 615             if (deserializeEx == null) {
 616                 deserializeEx = localDesc.deserializeEx;
 617             }
 618         }
 619         fieldRefl = getReflector(fields, localDesc);
 620         // reassign to matched fields so as to reflect local unshared settings
 621         fields = fieldRefl.getFields();
 622     }
 623 
 624     /**
 625      * Reads non-proxy class descriptor information from given input stream.
 626      * The resulting class descriptor is not fully functional; it can only be
 627      * used as input to the ObjectInputStream.resolveClass() and
 628      * ObjectStreamClass.initNonProxy() methods.
 629      */
 630     void readNonProxy(ObjectInputStream in)
 631         throws IOException, ClassNotFoundException
 632     {
 633         name = in.readUTF();
 634         suid = Long.valueOf(in.readLong());
 635         isProxy = false;
 636 
 637         byte flags = in.readByte();
 638         hasWriteObjectData =
 639             ((flags & ObjectStreamConstants.SC_WRITE_METHOD) != 0);
 640         hasBlockExternalData =
 641             ((flags & ObjectStreamConstants.SC_BLOCK_DATA) != 0);
 642         externalizable =
 643             ((flags & ObjectStreamConstants.SC_EXTERNALIZABLE) != 0);
 644         boolean sflag =
 645             ((flags & ObjectStreamConstants.SC_SERIALIZABLE) != 0);
 646         if (externalizable && sflag) {
 647             throw new InvalidClassException(
 648                 name, "serializable and externalizable flags conflict");
 649         }
 650         serializable = externalizable || sflag;
 651         isEnum = ((flags & ObjectStreamConstants.SC_ENUM) != 0);
 652         if (isEnum && suid.longValue() != 0L) {
 653             throw new InvalidClassException(name,
 654                 "enum descriptor has non-zero serialVersionUID: " + suid);
 655         }
 656 
 657         int numFields = in.readShort();
 658         if (isEnum && numFields != 0) {
 659             throw new InvalidClassException(name,
 660                 "enum descriptor has non-zero field count: " + numFields);
 661         }
 662         fields = (numFields > 0) ?
 663             new ObjectStreamField[numFields] : NO_FIELDS;
 664         for (int i = 0; i < numFields; i++) {
 665             char tcode = (char) in.readByte();
 666             String fname = in.readUTF();
 667             String signature = ((tcode == 'L') || (tcode == '[')) ?
 668                 in.readTypeString() : new String(new char[] { tcode });
 669             try {
 670                 fields[i] = new ObjectStreamField(fname, signature, false);
 671             } catch (RuntimeException e) {
 672                 throw (IOException) new InvalidClassException(name,
 673                     "invalid descriptor for field " + fname).initCause(e);
 674             }
 675         }
 676         computeFieldOffsets();
 677     }
 678 
 679     /**
 680      * Writes non-proxy class descriptor information to given output stream.
 681      */
 682     void writeNonProxy(ObjectOutputStream out) throws IOException {
 683         out.writeUTF(name);
 684         out.writeLong(getSerialVersionUID());
 685 
 686         byte flags = 0;
 687         if (externalizable) {
 688             flags |= ObjectStreamConstants.SC_EXTERNALIZABLE;
 689             int protocol = out.getProtocolVersion();
 690             if (protocol != ObjectStreamConstants.PROTOCOL_VERSION_1) {
 691                 flags |= ObjectStreamConstants.SC_BLOCK_DATA;
 692             }
 693         } else if (serializable) {
 694             flags |= ObjectStreamConstants.SC_SERIALIZABLE;
 695         }
 696         if (hasWriteObjectData) {
 697             flags |= ObjectStreamConstants.SC_WRITE_METHOD;
 698         }
 699         if (isEnum) {
 700             flags |= ObjectStreamConstants.SC_ENUM;
 701         }
 702         out.writeByte(flags);
 703 
 704         out.writeShort(fields.length);
 705         for (int i = 0; i < fields.length; i++) {
 706             ObjectStreamField f = fields[i];
 707             out.writeByte(f.getTypeCode());
 708             out.writeUTF(f.getName());
 709             if (!f.isPrimitive()) {
 710                 out.writeTypeString(f.getTypeString());
 711             }
 712         }
 713     }
 714 
 715     /**
 716      * Returns ClassNotFoundException (if any) thrown while attempting to
 717      * resolve local class corresponding to this class descriptor.
 718      */
 719     ClassNotFoundException getResolveException() {
 720         return resolveEx;
 721     }
 722 
 723     /**
 724      * Throws an InvalidClassException if object instances referencing this
 725      * class descriptor should not be allowed to deserialize.  This method does
 726      * not apply to deserialization of enum constants.
 727      */
 728     void checkDeserialize() throws InvalidClassException {
 729         if (deserializeEx != null) {
 730             InvalidClassException ice =
 731                 new InvalidClassException(deserializeEx.classname,
 732                                           deserializeEx.getMessage());
 733             ice.initCause(deserializeEx);
 734             throw ice;
 735         }
 736     }
 737 
 738     /**
 739      * Throws an InvalidClassException if objects whose class is represented by
 740      * this descriptor should not be allowed to serialize.  This method does
 741      * not apply to serialization of enum constants.
 742      */
 743     void checkSerialize() throws InvalidClassException {
 744         if (serializeEx != null) {
 745             InvalidClassException ice =
 746                 new InvalidClassException(serializeEx.classname,
 747                                           serializeEx.getMessage());
 748             ice.initCause(serializeEx);
 749             throw ice;
 750         }
 751     }
 752 
 753     /**
 754      * Throws an InvalidClassException if objects whose class is represented by
 755      * this descriptor should not be permitted to use default serialization
 756      * (e.g., if the class declares serializable fields that do not correspond
 757      * to actual fields, and hence must use the GetField API).  This method
 758      * does not apply to deserialization of enum constants.
 759      */
 760     void checkDefaultSerialize() throws InvalidClassException {
 761         if (defaultSerializeEx != null) {
 762             InvalidClassException ice =
 763                 new InvalidClassException(defaultSerializeEx.classname,
 764                                           defaultSerializeEx.getMessage());
 765             ice.initCause(defaultSerializeEx);
 766             throw ice;
 767         }
 768     }
 769 
 770     /**
 771      * Returns superclass descriptor.  Note that on the receiving side, the
 772      * superclass descriptor may be bound to a class that is not a superclass
 773      * of the subclass descriptor's bound class.
 774      */
 775     ObjectStreamClass getSuperDesc() {
 776         return superDesc;
 777     }
 778 
 779     /**
 780      * Returns the "local" class descriptor for the class associated with this
 781      * class descriptor (i.e., the result of
 782      * ObjectStreamClass.lookup(this.forClass())) or null if there is no class
 783      * associated with this descriptor.
 784      */
 785     ObjectStreamClass getLocalDesc() {
 786         return localDesc;
 787     }
 788 
 789     /**
 790      * Returns arrays of ObjectStreamFields representing the serializable
 791      * fields of the represented class.  If copy is true, a clone of this class
 792      * descriptor's field array is returned, otherwise the array itself is
 793      * returned.
 794      */
 795     ObjectStreamField[] getFields(boolean copy) {
 796         return copy ? fields.clone() : fields;
 797     }
 798 
 799     /**
 800      * Looks up a serializable field of the represented class by name and type.
 801      * A specified type of null matches all types, Object.class matches all
 802      * non-primitive types, and any other non-null type matches assignable
 803      * types only.  Returns matching field, or null if no match found.
 804      */
 805     ObjectStreamField getField(String name, Class<?> type) {
 806         for (int i = 0; i < fields.length; i++) {
 807             ObjectStreamField f = fields[i];
 808             if (f.getName().equals(name)) {
 809                 if (type == null ||
 810                     (type == Object.class && !f.isPrimitive()))
 811                 {
 812                     return f;
 813                 }
 814                 Class<?> ftype = f.getType();
 815                 if (ftype != null && type.isAssignableFrom(ftype)) {
 816                     return f;
 817                 }
 818             }
 819         }
 820         return null;
 821     }
 822 
 823     /**
 824      * Returns true if class descriptor represents a dynamic proxy class, false
 825      * otherwise.
 826      */
 827     boolean isProxy() {
 828         return isProxy;
 829     }
 830 
 831     /**
 832      * Returns true if class descriptor represents an enum type, false
 833      * otherwise.
 834      */
 835     boolean isEnum() {
 836         return isEnum;
 837     }
 838 
 839     /**
 840      * Returns true if represented class implements Externalizable, false
 841      * otherwise.
 842      */
 843     boolean isExternalizable() {
 844         return externalizable;
 845     }
 846 
 847     /**
 848      * Returns true if represented class implements Serializable, false
 849      * otherwise.
 850      */
 851     boolean isSerializable() {
 852         return serializable;
 853     }
 854 
 855     /**
 856      * Returns true if class descriptor represents externalizable class that
 857      * has written its data in 1.2 (block data) format, false otherwise.
 858      */
 859     boolean hasBlockExternalData() {
 860         return hasBlockExternalData;
 861     }
 862 
 863     /**
 864      * Returns true if class descriptor represents serializable (but not
 865      * externalizable) class which has written its data via a custom
 866      * writeObject() method, false otherwise.
 867      */
 868     boolean hasWriteObjectData() {
 869         return hasWriteObjectData;
 870     }
 871 
 872     /**
 873      * Returns true if represented class is serializable/externalizable and can
 874      * be instantiated by the serialization runtime--i.e., if it is
 875      * externalizable and defines a public no-arg constructor, or if it is
 876      * non-externalizable and its first non-serializable superclass defines an
 877      * accessible no-arg constructor.  Otherwise, returns false.
 878      */
 879     boolean isInstantiable() {
 880         return (cons != null);
 881     }
 882 
 883     /**
 884      * Returns true if represented class is serializable (but not
 885      * externalizable) and defines a conformant writeObject method.  Otherwise,
 886      * returns false.
 887      */
 888     boolean hasWriteObjectMethod() {
 889         return (writeObjectMethod != null);
 890     }
 891 
 892     /**
 893      * Returns true if represented class is serializable (but not
 894      * externalizable) and defines a conformant readObject method.  Otherwise,
 895      * returns false.
 896      */
 897     boolean hasReadObjectMethod() {
 898         return (readObjectMethod != null);
 899     }
 900 
 901     /**
 902      * Returns true if represented class is serializable (but not
 903      * externalizable) and defines a conformant readObjectNoData method.
 904      * Otherwise, returns false.
 905      */
 906     boolean hasReadObjectNoDataMethod() {
 907         return (readObjectNoDataMethod != null);
 908     }
 909 
 910     /**
 911      * Returns true if represented class is serializable or externalizable and
 912      * defines a conformant writeReplace method.  Otherwise, returns false.
 913      */
 914     boolean hasWriteReplaceMethod() {
 915         return (writeReplaceMethod != null);
 916     }
 917 
 918     /**
 919      * Returns true if represented class is serializable or externalizable and
 920      * defines a conformant readResolve method.  Otherwise, returns false.
 921      */
 922     boolean hasReadResolveMethod() {
 923         return (readResolveMethod != null);
 924     }
 925 
 926     /**
 927      * Creates a new instance of the represented class.  If the class is
 928      * externalizable, invokes its public no-arg constructor; otherwise, if the
 929      * class is serializable, invokes the no-arg constructor of the first
 930      * non-serializable superclass.  Throws UnsupportedOperationException if
 931      * this class descriptor is not associated with a class, if the associated
 932      * class is non-serializable or if the appropriate no-arg constructor is
 933      * inaccessible/unavailable.
 934      */
 935     Object newInstance()
 936         throws InstantiationException, InvocationTargetException,
 937                UnsupportedOperationException
 938     {
 939         if (cons != null) {
 940             try {
 941                 return cons.newInstance();
 942             } catch (IllegalAccessException ex) {
 943                 // should not occur, as access checks have been suppressed
 944                 throw new InternalError(ex);
 945             }
 946         } else {
 947             throw new UnsupportedOperationException();
 948         }
 949     }
 950 
 951     /**
 952      * Invokes the writeObject method of the represented serializable class.
 953      * Throws UnsupportedOperationException if this class descriptor is not
 954      * associated with a class, or if the class is externalizable,
 955      * non-serializable or does not define writeObject.
 956      */
 957     void invokeWriteObject(Object obj, ObjectOutputStream out)
 958         throws IOException, UnsupportedOperationException
 959     {
 960         if (writeObjectMethod != null) {
 961             try {
 962                 writeObjectMethod.invoke(obj, new Object[]{ out });
 963             } catch (InvocationTargetException ex) {
 964                 Throwable th = ex.getTargetException();
 965                 if (th instanceof IOException) {
 966                     throw (IOException) th;
 967                 } else {
 968                     throwMiscException(th);
 969                 }
 970             } catch (IllegalAccessException ex) {
 971                 // should not occur, as access checks have been suppressed
 972                 throw new InternalError(ex);
 973             }
 974         } else {
 975             throw new UnsupportedOperationException();
 976         }
 977     }
 978 
 979     /**
 980      * Invokes the readObject method of the represented serializable class.
 981      * Throws UnsupportedOperationException if this class descriptor is not
 982      * associated with a class, or if the class is externalizable,
 983      * non-serializable or does not define readObject.
 984      */
 985     void invokeReadObject(Object obj, ObjectInputStream in)
 986         throws ClassNotFoundException, IOException,
 987                UnsupportedOperationException
 988     {
 989         if (readObjectMethod != null) {
 990             try {
 991                 readObjectMethod.invoke(obj, new Object[]{ in });
 992             } catch (InvocationTargetException ex) {
 993                 Throwable th = ex.getTargetException();
 994                 if (th instanceof ClassNotFoundException) {
 995                     throw (ClassNotFoundException) th;
 996                 } else if (th instanceof IOException) {
 997                     throw (IOException) th;
 998                 } else {
 999                     throwMiscException(th);
1000                 }
1001             } catch (IllegalAccessException ex) {
1002                 // should not occur, as access checks have been suppressed
1003                 throw new InternalError(ex);
1004             }
1005         } else {
1006             throw new UnsupportedOperationException();
1007         }
1008     }
1009 
1010     /**
1011      * Invokes the readObjectNoData method of the represented serializable
1012      * class.  Throws UnsupportedOperationException if this class descriptor is
1013      * not associated with a class, or if the class is externalizable,
1014      * non-serializable or does not define readObjectNoData.
1015      */
1016     void invokeReadObjectNoData(Object obj)
1017         throws IOException, UnsupportedOperationException
1018     {
1019         if (readObjectNoDataMethod != null) {
1020             try {
1021                 readObjectNoDataMethod.invoke(obj, (Object[]) null);
1022             } catch (InvocationTargetException ex) {
1023                 Throwable th = ex.getTargetException();
1024                 if (th instanceof ObjectStreamException) {
1025                     throw (ObjectStreamException) th;
1026                 } else {
1027                     throwMiscException(th);
1028                 }
1029             } catch (IllegalAccessException ex) {
1030                 // should not occur, as access checks have been suppressed
1031                 throw new InternalError(ex);
1032             }
1033         } else {
1034             throw new UnsupportedOperationException();
1035         }
1036     }
1037 
1038     /**
1039      * Invokes the writeReplace method of the represented serializable class and
1040      * returns the result.  Throws UnsupportedOperationException if this class
1041      * descriptor is not associated with a class, or if the class is
1042      * non-serializable or does not define writeReplace.
1043      */
1044     Object invokeWriteReplace(Object obj)
1045         throws IOException, UnsupportedOperationException
1046     {
1047         if (writeReplaceMethod != null) {
1048             try {
1049                 return writeReplaceMethod.invoke(obj, (Object[]) null);
1050             } catch (InvocationTargetException ex) {
1051                 Throwable th = ex.getTargetException();
1052                 if (th instanceof ObjectStreamException) {
1053                     throw (ObjectStreamException) th;
1054                 } else {
1055                     throwMiscException(th);
1056                     throw new InternalError(th);  // never reached
1057                 }
1058             } catch (IllegalAccessException ex) {
1059                 // should not occur, as access checks have been suppressed
1060                 throw new InternalError(ex);
1061             }
1062         } else {
1063             throw new UnsupportedOperationException();
1064         }
1065     }
1066 
1067     /**
1068      * Invokes the readResolve method of the represented serializable class and
1069      * returns the result.  Throws UnsupportedOperationException if this class
1070      * descriptor is not associated with a class, or if the class is
1071      * non-serializable or does not define readResolve.
1072      */
1073     Object invokeReadResolve(Object obj)
1074         throws IOException, UnsupportedOperationException
1075     {
1076         if (readResolveMethod != null) {
1077             try {
1078                 return readResolveMethod.invoke(obj, (Object[]) null);
1079             } catch (InvocationTargetException ex) {
1080                 Throwable th = ex.getTargetException();
1081                 if (th instanceof ObjectStreamException) {
1082                     throw (ObjectStreamException) th;
1083                 } else {
1084                     throwMiscException(th);
1085                     throw new InternalError(th);  // never reached
1086                 }
1087             } catch (IllegalAccessException ex) {
1088                 // should not occur, as access checks have been suppressed
1089                 throw new InternalError(ex);
1090             }
1091         } else {
1092             throw new UnsupportedOperationException();
1093         }
1094     }
1095 
1096     /**
1097      * Class representing the portion of an object's serialized form allotted
1098      * to data described by a given class descriptor.  If "hasData" is false,
1099      * the object's serialized form does not contain data associated with the
1100      * class descriptor.
1101      */
1102     static class ClassDataSlot {
1103 
1104         /** class descriptor "occupying" this slot */
1105         final ObjectStreamClass desc;
1106         /** true if serialized form includes data for this slot's descriptor */
1107         final boolean hasData;
1108 
1109         ClassDataSlot(ObjectStreamClass desc, boolean hasData) {
1110             this.desc = desc;
1111             this.hasData = hasData;
1112         }
1113     }
1114 
1115     /**
1116      * Returns array of ClassDataSlot instances representing the data layout
1117      * (including superclass data) for serialized objects described by this
1118      * class descriptor.  ClassDataSlots are ordered by inheritance with those
1119      * containing "higher" superclasses appearing first.  The final
1120      * ClassDataSlot contains a reference to this descriptor.
1121      */
1122     ClassDataSlot[] getClassDataLayout() throws InvalidClassException {
1123         // REMIND: synchronize instead of relying on volatile?
1124         if (dataLayout == null) {
1125             dataLayout = getClassDataLayout0();
1126         }
1127         return dataLayout;
1128     }
1129 
1130     private ClassDataSlot[] getClassDataLayout0()
1131         throws InvalidClassException
1132     {
1133         ArrayList<ClassDataSlot> slots = new ArrayList<>();
1134         Class<?> start = cl, end = cl;
1135 
1136         // locate closest non-serializable superclass
1137         while (end != null && Serializable.class.isAssignableFrom(end)) {
1138             end = end.getSuperclass();
1139         }
1140 
1141         for (ObjectStreamClass d = this; d != null; d = d.superDesc) {
1142 
1143             // search up inheritance hierarchy for class with matching name
1144             String searchName = (d.cl != null) ? d.cl.getName() : d.name;
1145             Class<?> match = null;
1146             for (Class<?> c = start; c != end; c = c.getSuperclass()) {
1147                 if (searchName.equals(c.getName())) {
1148                     match = c;
1149                     break;
1150                 }
1151             }
1152 
1153             // add "no data" slot for each unmatched class below match
1154             if (match != null) {
1155                 for (Class<?> c = start; c != match; c = c.getSuperclass()) {
1156                     slots.add(new ClassDataSlot(
1157                         ObjectStreamClass.lookup(c, true), false));
1158                 }
1159                 start = match.getSuperclass();
1160             }
1161 
1162             // record descriptor/class pairing
1163             slots.add(new ClassDataSlot(d.getVariantFor(match), true));
1164         }
1165 
1166         // add "no data" slot for any leftover unmatched classes
1167         for (Class<?> c = start; c != end; c = c.getSuperclass()) {
1168             slots.add(new ClassDataSlot(
1169                 ObjectStreamClass.lookup(c, true), false));
1170         }
1171 
1172         // order slots from superclass -> subclass
1173         Collections.reverse(slots);
1174         return slots.toArray(new ClassDataSlot[slots.size()]);
1175     }
1176 
1177     /**
1178      * Returns aggregate size (in bytes) of marshalled primitive field values
1179      * for represented class.
1180      */
1181     int getPrimDataSize() {
1182         return primDataSize;
1183     }
1184 
1185     /**
1186      * Returns number of non-primitive serializable fields of represented
1187      * class.
1188      */
1189     int getNumObjFields() {
1190         return numObjFields;
1191     }
1192 
1193     /**
1194      * Fetches the serializable primitive field values of object obj and
1195      * marshals them into byte array buf starting at offset 0.  It is the
1196      * responsibility of the caller to ensure that obj is of the proper type if
1197      * non-null.
1198      */
1199     void getPrimFieldValues(Object obj, byte[] buf) {
1200         fieldRefl.getPrimFieldValues(obj, buf);
1201     }
1202 
1203     /**
1204      * Sets the serializable primitive fields of object obj using values
1205      * unmarshalled from byte array buf starting at offset 0.  It is the
1206      * responsibility of the caller to ensure that obj is of the proper type if
1207      * non-null.
1208      */
1209     void setPrimFieldValues(Object obj, byte[] buf) {
1210         fieldRefl.setPrimFieldValues(obj, buf);
1211     }
1212 
1213     /**
1214      * Fetches the serializable object field values of object obj and stores
1215      * them in array vals starting at offset 0.  It is the responsibility of
1216      * the caller to ensure that obj is of the proper type if non-null.
1217      */
1218     void getObjFieldValues(Object obj, Object[] vals) {
1219         fieldRefl.getObjFieldValues(obj, vals);
1220     }
1221 
1222     /**
1223      * Sets the serializable object fields of object obj using values from
1224      * array vals starting at offset 0.  It is the responsibility of the caller
1225      * to ensure that obj is of the proper type if non-null.
1226      */
1227     void setObjFieldValues(Object obj, Object[] vals) {
1228         fieldRefl.setObjFieldValues(obj, vals);
1229     }
1230 
1231     /**
1232      * Calculates and sets serializable field offsets, as well as primitive
1233      * data size and object field count totals.  Throws InvalidClassException
1234      * if fields are illegally ordered.
1235      */
1236     private void computeFieldOffsets() throws InvalidClassException {
1237         primDataSize = 0;
1238         numObjFields = 0;
1239         int firstObjIndex = -1;
1240 
1241         for (int i = 0; i < fields.length; i++) {
1242             ObjectStreamField f = fields[i];
1243             switch (f.getTypeCode()) {
1244                 case 'Z':
1245                 case 'B':
1246                     f.setOffset(primDataSize++);
1247                     break;
1248 
1249                 case 'C':
1250                 case 'S':
1251                     f.setOffset(primDataSize);
1252                     primDataSize += 2;
1253                     break;
1254 
1255                 case 'I':
1256                 case 'F':
1257                     f.setOffset(primDataSize);
1258                     primDataSize += 4;
1259                     break;
1260 
1261                 case 'J':
1262                 case 'D':
1263                     f.setOffset(primDataSize);
1264                     primDataSize += 8;
1265                     break;
1266 
1267                 case '[':
1268                 case 'L':
1269                     f.setOffset(numObjFields++);
1270                     if (firstObjIndex == -1) {
1271                         firstObjIndex = i;
1272                     }
1273                     break;
1274 
1275                 default:
1276                     throw new InternalError();
1277             }
1278         }
1279         if (firstObjIndex != -1 &&
1280             firstObjIndex + numObjFields != fields.length)
1281         {
1282             throw new InvalidClassException(name, "illegal field order");
1283         }
1284     }
1285 
1286     /**
1287      * If given class is the same as the class associated with this class
1288      * descriptor, returns reference to this class descriptor.  Otherwise,
1289      * returns variant of this class descriptor bound to given class.
1290      */
1291     private ObjectStreamClass getVariantFor(Class<?> cl)
1292         throws InvalidClassException
1293     {
1294         if (this.cl == cl) {
1295             return this;
1296         }
1297         ObjectStreamClass desc = new ObjectStreamClass();
1298         if (isProxy) {
1299             desc.initProxy(cl, null, superDesc);
1300         } else {
1301             desc.initNonProxy(this, cl, null, superDesc);
1302         }
1303         return desc;
1304     }
1305 
1306     /**
1307      * Returns public no-arg constructor of given class, or null if none found.
1308      * Access checks are disabled on the returned constructor (if any), since
1309      * the defining class may still be non-public.
1310      */
1311     private static Constructor<?> getExternalizableConstructor(Class<?> cl) {
1312         try {
1313             Constructor<?> cons = cl.getDeclaredConstructor((Class<?>[]) null);
1314             cons.setAccessible(true);
1315             return ((cons.getModifiers() & Modifier.PUBLIC) != 0) ?
1316                 cons : null;
1317         } catch (NoSuchMethodException ex) {
1318             return null;
1319         }
1320     }
1321 
1322     /**
1323      * Returns subclass-accessible no-arg constructor of first non-serializable
1324      * superclass, or null if none found.  Access checks are disabled on the
1325      * returned constructor (if any).
1326      */
1327     private static Constructor<?> getSerializableConstructor(Class<?> cl) {
1328         Class<?> initCl = cl;
1329         while (Serializable.class.isAssignableFrom(initCl)) {
1330             if ((initCl = initCl.getSuperclass()) == null) {
1331                 return null;
1332             }
1333         }
1334         try {
1335             Constructor<?> cons = initCl.getDeclaredConstructor((Class<?>[]) null);
1336             int mods = cons.getModifiers();
1337             if ((mods & Modifier.PRIVATE) != 0 ||
1338                 ((mods & (Modifier.PUBLIC | Modifier.PROTECTED)) == 0 &&
1339                  !packageEquals(cl, initCl)))
1340             {
1341                 return null;
1342             }
1343             cons = reflFactory.newConstructorForSerialization(cl, cons);
1344             cons.setAccessible(true);
1345             return cons;
1346         } catch (NoSuchMethodException ex) {
1347             return null;
1348         }
1349     }
1350 
1351     /**
1352      * Returns non-static, non-abstract method with given signature provided it
1353      * is defined by or accessible (via inheritance) by the given class, or
1354      * null if no match found.  Access checks are disabled on the returned
1355      * method (if any).
1356      */
1357     private static Method getInheritableMethod(Class<?> cl, String name,
1358                                                Class<?>[] argTypes,
1359                                                Class<?> returnType)
1360     {
1361         Method meth = null;
1362         Class<?> defCl = cl;
1363         while (defCl != null) {
1364             try {
1365                 meth = defCl.getDeclaredMethod(name, argTypes);
1366                 break;
1367             } catch (NoSuchMethodException ex) {
1368                 defCl = defCl.getSuperclass();
1369             }
1370         }
1371 
1372         if ((meth == null) || (meth.getReturnType() != returnType)) {
1373             return null;
1374         }
1375         meth.setAccessible(true);
1376         int mods = meth.getModifiers();
1377         if ((mods & (Modifier.STATIC | Modifier.ABSTRACT)) != 0) {
1378             return null;
1379         } else if ((mods & (Modifier.PUBLIC | Modifier.PROTECTED)) != 0) {
1380             return meth;
1381         } else if ((mods & Modifier.PRIVATE) != 0) {
1382             return (cl == defCl) ? meth : null;
1383         } else {
1384             return packageEquals(cl, defCl) ? meth : null;
1385         }
1386     }
1387 
1388     /**
1389      * Returns non-static private method with given signature defined by given
1390      * class, or null if none found.  Access checks are disabled on the
1391      * returned method (if any).
1392      */
1393     private static Method getPrivateMethod(Class<?> cl, String name,
1394                                            Class<?>[] argTypes,
1395                                            Class<?> returnType)
1396     {
1397         try {
1398             Method meth = cl.getDeclaredMethod(name, argTypes);
1399             meth.setAccessible(true);
1400             int mods = meth.getModifiers();
1401             return ((meth.getReturnType() == returnType) &&
1402                     ((mods & Modifier.STATIC) == 0) &&
1403                     ((mods & Modifier.PRIVATE) != 0)) ? meth : null;
1404         } catch (NoSuchMethodException ex) {
1405             return null;
1406         }
1407     }
1408 
1409     /**
1410      * Returns true if classes are defined in the same runtime package, false
1411      * otherwise.
1412      */
1413     private static boolean packageEquals(Class<?> cl1, Class<?> cl2) {
1414         return (cl1.getClassLoader() == cl2.getClassLoader() &&
1415                 getPackageName(cl1).equals(getPackageName(cl2)));
1416     }
1417 
1418     /**
1419      * Returns package name of given class.
1420      */
1421     private static String getPackageName(Class<?> cl) {
1422         String s = cl.getName();
1423         int i = s.lastIndexOf('[');
1424         if (i >= 0) {
1425             s = s.substring(i + 2);
1426         }
1427         i = s.lastIndexOf('.');
1428         return (i >= 0) ? s.substring(0, i) : "";
1429     }
1430 
1431     /**
1432      * Compares class names for equality, ignoring package names.  Returns true
1433      * if class names equal, false otherwise.
1434      */
1435     private static boolean classNamesEqual(String name1, String name2) {
1436         name1 = name1.substring(name1.lastIndexOf('.') + 1);
1437         name2 = name2.substring(name2.lastIndexOf('.') + 1);
1438         return name1.equals(name2);
1439     }
1440 
1441     /**
1442      * Returns JVM type signature for given class.
1443      */
1444     private static String getClassSignature(Class<?> cl) {
1445         StringBuilder sbuf = new StringBuilder();
1446         while (cl.isArray()) {
1447             sbuf.append('[');
1448             cl = cl.getComponentType();
1449         }
1450         if (cl.isPrimitive()) {
1451             if (cl == Integer.TYPE) {
1452                 sbuf.append('I');
1453             } else if (cl == Byte.TYPE) {
1454                 sbuf.append('B');
1455             } else if (cl == Long.TYPE) {
1456                 sbuf.append('J');
1457             } else if (cl == Float.TYPE) {
1458                 sbuf.append('F');
1459             } else if (cl == Double.TYPE) {
1460                 sbuf.append('D');
1461             } else if (cl == Short.TYPE) {
1462                 sbuf.append('S');
1463             } else if (cl == Character.TYPE) {
1464                 sbuf.append('C');
1465             } else if (cl == Boolean.TYPE) {
1466                 sbuf.append('Z');
1467             } else if (cl == Void.TYPE) {
1468                 sbuf.append('V');
1469             } else {
1470                 throw new InternalError();
1471             }
1472         } else {
1473             sbuf.append('L' + cl.getName().replace('.', '/') + ';');
1474         }
1475         return sbuf.toString();
1476     }
1477 
1478     /**
1479      * Returns JVM type signature for given list of parameters and return type.
1480      */
1481     private static String getMethodSignature(Class<?>[] paramTypes,
1482                                              Class<?> retType)
1483     {
1484         StringBuilder sbuf = new StringBuilder();
1485         sbuf.append('(');
1486         for (int i = 0; i < paramTypes.length; i++) {
1487             sbuf.append(getClassSignature(paramTypes[i]));
1488         }
1489         sbuf.append(')');
1490         sbuf.append(getClassSignature(retType));
1491         return sbuf.toString();
1492     }
1493 
1494     /**
1495      * Convenience method for throwing an exception that is either a
1496      * RuntimeException, Error, or of some unexpected type (in which case it is
1497      * wrapped inside an IOException).
1498      */
1499     private static void throwMiscException(Throwable th) throws IOException {
1500         if (th instanceof RuntimeException) {
1501             throw (RuntimeException) th;
1502         } else if (th instanceof Error) {
1503             throw (Error) th;
1504         } else {
1505             IOException ex = new IOException("unexpected exception type");
1506             ex.initCause(th);
1507             throw ex;
1508         }
1509     }
1510 
1511     /**
1512      * Returns ObjectStreamField array describing the serializable fields of
1513      * the given class.  Serializable fields backed by an actual field of the
1514      * class are represented by ObjectStreamFields with corresponding non-null
1515      * Field objects.  Throws InvalidClassException if the (explicitly
1516      * declared) serializable fields are invalid.
1517      */
1518     private static ObjectStreamField[] getSerialFields(Class<?> cl)
1519         throws InvalidClassException
1520     {
1521         ObjectStreamField[] fields;
1522         if (Serializable.class.isAssignableFrom(cl) &&
1523             !Externalizable.class.isAssignableFrom(cl) &&
1524             !Proxy.isProxyClass(cl) &&
1525             !cl.isInterface())
1526         {
1527             if ((fields = getDeclaredSerialFields(cl)) == null) {
1528                 fields = getDefaultSerialFields(cl);
1529             }
1530             Arrays.sort(fields);
1531         } else {
1532             fields = NO_FIELDS;
1533         }
1534         return fields;
1535     }
1536 
1537     /**
1538      * Returns serializable fields of given class as defined explicitly by a
1539      * "serialPersistentFields" field, or null if no appropriate
1540      * "serialPersistentFields" field is defined.  Serializable fields backed
1541      * by an actual field of the class are represented by ObjectStreamFields
1542      * with corresponding non-null Field objects.  For compatibility with past
1543      * releases, a "serialPersistentFields" field with a null value is
1544      * considered equivalent to not declaring "serialPersistentFields".  Throws
1545      * InvalidClassException if the declared serializable fields are
1546      * invalid--e.g., if multiple fields share the same name.
1547      */
1548     private static ObjectStreamField[] getDeclaredSerialFields(Class<?> cl)
1549         throws InvalidClassException
1550     {
1551         ObjectStreamField[] serialPersistentFields = null;
1552         try {
1553             Field f = cl.getDeclaredField("serialPersistentFields");
1554             int mask = Modifier.PRIVATE | Modifier.STATIC | Modifier.FINAL;
1555             if ((f.getModifiers() & mask) == mask) {
1556                 f.setAccessible(true);
1557                 serialPersistentFields = (ObjectStreamField[]) f.get(null);
1558             }
1559         } catch (Exception ex) {
1560         }
1561         if (serialPersistentFields == null) {
1562             return null;
1563         } else if (serialPersistentFields.length == 0) {
1564             return NO_FIELDS;
1565         }
1566 
1567         ObjectStreamField[] boundFields =
1568             new ObjectStreamField[serialPersistentFields.length];
1569         Set<String> fieldNames = new HashSet<>(serialPersistentFields.length);
1570 
1571         for (int i = 0; i < serialPersistentFields.length; i++) {
1572             ObjectStreamField spf = serialPersistentFields[i];
1573 
1574             String fname = spf.getName();
1575             if (fieldNames.contains(fname)) {
1576                 throw new InvalidClassException(
1577                     "multiple serializable fields named " + fname);
1578             }
1579             fieldNames.add(fname);
1580 
1581             try {
1582                 Field f = cl.getDeclaredField(fname);
1583                 if ((f.getType() == spf.getType()) &&
1584                     ((f.getModifiers() & Modifier.STATIC) == 0))
1585                 {
1586                     boundFields[i] =
1587                         new ObjectStreamField(f, spf.isUnshared(), true);
1588                 }
1589             } catch (NoSuchFieldException ex) {
1590             }
1591             if (boundFields[i] == null) {
1592                 boundFields[i] = new ObjectStreamField(
1593                     fname, spf.getType(), spf.isUnshared());
1594             }
1595         }
1596         return boundFields;
1597     }
1598 
1599     /**
1600      * Returns array of ObjectStreamFields corresponding to all non-static
1601      * non-transient fields declared by given class.  Each ObjectStreamField
1602      * contains a Field object for the field it represents.  If no default
1603      * serializable fields exist, NO_FIELDS is returned.
1604      */
1605     private static ObjectStreamField[] getDefaultSerialFields(Class<?> cl) {
1606         Field[] clFields = cl.getDeclaredFields();
1607         ArrayList<ObjectStreamField> list = new ArrayList<>();
1608         int mask = Modifier.STATIC | Modifier.TRANSIENT;
1609 
1610         for (int i = 0; i < clFields.length; i++) {
1611             if ((clFields[i].getModifiers() & mask) == 0) {
1612                 list.add(new ObjectStreamField(clFields[i], false, true));
1613             }
1614         }
1615         int size = list.size();
1616         return (size == 0) ? NO_FIELDS :
1617             list.toArray(new ObjectStreamField[size]);
1618     }
1619 
1620     /**
1621      * Returns explicit serial version UID value declared by given class, or
1622      * null if none.
1623      */
1624     private static Long getDeclaredSUID(Class<?> cl) {
1625         try {
1626             Field f = cl.getDeclaredField("serialVersionUID");
1627             int mask = Modifier.STATIC | Modifier.FINAL;
1628             if ((f.getModifiers() & mask) == mask) {
1629                 f.setAccessible(true);
1630                 return Long.valueOf(f.getLong(null));
1631             }
1632         } catch (Exception ex) {
1633         }
1634         return null;
1635     }
1636 
1637     /**
1638      * Computes the default serial version UID value for the given class.
1639      */
1640     private static long computeDefaultSUID(Class<?> cl) {
1641         if (!Serializable.class.isAssignableFrom(cl) || Proxy.isProxyClass(cl))
1642         {
1643             return 0L;
1644         }
1645 
1646         try {
1647             ByteArrayOutputStream bout = new ByteArrayOutputStream();
1648             DataOutputStream dout = new DataOutputStream(bout);
1649 
1650             dout.writeUTF(cl.getName());
1651 
1652             int classMods = cl.getModifiers() &
1653                 (Modifier.PUBLIC | Modifier.FINAL |
1654                  Modifier.INTERFACE | Modifier.ABSTRACT);
1655 
1656             /*
1657              * compensate for javac bug in which ABSTRACT bit was set for an
1658              * interface only if the interface declared methods
1659              */
1660             Method[] methods = cl.getDeclaredMethods();
1661             if ((classMods & Modifier.INTERFACE) != 0) {
1662                 classMods = (methods.length > 0) ?
1663                     (classMods | Modifier.ABSTRACT) :
1664                     (classMods & ~Modifier.ABSTRACT);
1665             }
1666             dout.writeInt(classMods);
1667 
1668             if (!cl.isArray()) {
1669                 /*
1670                  * compensate for change in 1.2FCS in which
1671                  * Class.getInterfaces() was modified to return Cloneable and
1672                  * Serializable for array classes.
1673                  */
1674                 Class<?>[] interfaces = cl.getInterfaces();
1675                 String[] ifaceNames = new String[interfaces.length];
1676                 for (int i = 0; i < interfaces.length; i++) {
1677                     ifaceNames[i] = interfaces[i].getName();
1678                 }
1679                 Arrays.sort(ifaceNames);
1680                 for (int i = 0; i < ifaceNames.length; i++) {
1681                     dout.writeUTF(ifaceNames[i]);
1682                 }
1683             }
1684 
1685             Field[] fields = cl.getDeclaredFields();
1686             MemberSignature[] fieldSigs = new MemberSignature[fields.length];
1687             for (int i = 0; i < fields.length; i++) {
1688                 fieldSigs[i] = new MemberSignature(fields[i]);
1689             }
1690             Arrays.sort(fieldSigs, new Comparator<MemberSignature>() {
1691                 public int compare(MemberSignature ms1, MemberSignature ms2) {
1692                     return ms1.name.compareTo(ms2.name);
1693                 }
1694             });
1695             for (int i = 0; i < fieldSigs.length; i++) {
1696                 MemberSignature sig = fieldSigs[i];
1697                 int mods = sig.member.getModifiers() &
1698                     (Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED |
1699                      Modifier.STATIC | Modifier.FINAL | Modifier.VOLATILE |
1700                      Modifier.TRANSIENT);
1701                 if (((mods & Modifier.PRIVATE) == 0) ||
1702                     ((mods & (Modifier.STATIC | Modifier.TRANSIENT)) == 0))
1703                 {
1704                     dout.writeUTF(sig.name);
1705                     dout.writeInt(mods);
1706                     dout.writeUTF(sig.signature);
1707                 }
1708             }
1709 
1710             if (hasStaticInitializer(cl)) {
1711                 dout.writeUTF("<clinit>");
1712                 dout.writeInt(Modifier.STATIC);
1713                 dout.writeUTF("()V");
1714             }
1715 
1716             Constructor[] cons = cl.getDeclaredConstructors();
1717             MemberSignature[] consSigs = new MemberSignature[cons.length];
1718             for (int i = 0; i < cons.length; i++) {
1719                 consSigs[i] = new MemberSignature(cons[i]);
1720             }
1721             Arrays.sort(consSigs, new Comparator<MemberSignature>() {
1722                 public int compare(MemberSignature ms1, MemberSignature ms2) {
1723                     return ms1.signature.compareTo(ms2.signature);
1724                 }
1725             });
1726             for (int i = 0; i < consSigs.length; i++) {
1727                 MemberSignature sig = consSigs[i];
1728                 int mods = sig.member.getModifiers() &
1729                     (Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED |
1730                      Modifier.STATIC | Modifier.FINAL |
1731                      Modifier.SYNCHRONIZED | Modifier.NATIVE |
1732                      Modifier.ABSTRACT | Modifier.STRICT);
1733                 if ((mods & Modifier.PRIVATE) == 0) {
1734                     dout.writeUTF("<init>");
1735                     dout.writeInt(mods);
1736                     dout.writeUTF(sig.signature.replace('/', '.'));
1737                 }
1738             }
1739 
1740             MemberSignature[] methSigs = new MemberSignature[methods.length];
1741             for (int i = 0; i < methods.length; i++) {
1742                 methSigs[i] = new MemberSignature(methods[i]);
1743             }
1744             Arrays.sort(methSigs, new Comparator<MemberSignature>() {
1745                 public int compare(MemberSignature ms1, MemberSignature ms2) {
1746                     int comp = ms1.name.compareTo(ms2.name);
1747                     if (comp == 0) {
1748                         comp = ms1.signature.compareTo(ms2.signature);
1749                     }
1750                     return comp;
1751                 }
1752             });
1753             for (int i = 0; i < methSigs.length; i++) {
1754                 MemberSignature sig = methSigs[i];
1755                 int mods = sig.member.getModifiers() &
1756                     (Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED |
1757                      Modifier.STATIC | Modifier.FINAL |
1758                      Modifier.SYNCHRONIZED | Modifier.NATIVE |
1759                      Modifier.ABSTRACT | Modifier.STRICT);
1760                 if ((mods & Modifier.PRIVATE) == 0) {
1761                     dout.writeUTF(sig.name);
1762                     dout.writeInt(mods);
1763                     dout.writeUTF(sig.signature.replace('/', '.'));
1764                 }
1765             }
1766 
1767             dout.flush();
1768 
1769             MessageDigest md = MessageDigest.getInstance("SHA");
1770             byte[] hashBytes = md.digest(bout.toByteArray());
1771             long hash = 0;
1772             for (int i = Math.min(hashBytes.length, 8) - 1; i >= 0; i--) {
1773                 hash = (hash << 8) | (hashBytes[i] & 0xFF);
1774             }
1775             return hash;
1776         } catch (IOException ex) {
1777             throw new InternalError(ex);
1778         } catch (NoSuchAlgorithmException ex) {
1779             throw new SecurityException(ex.getMessage());
1780         }
1781     }
1782 
1783     /**
1784      * Returns true if the given class defines a static initializer method,
1785      * false otherwise.
1786      */
1787     private native static boolean hasStaticInitializer(Class<?> cl);
1788 
1789     /**
1790      * Class for computing and caching field/constructor/method signatures
1791      * during serialVersionUID calculation.
1792      */
1793     private static class MemberSignature {
1794 
1795         public final Member member;
1796         public final String name;
1797         public final String signature;
1798 
1799         public MemberSignature(Field field) {
1800             member = field;
1801             name = field.getName();
1802             signature = getClassSignature(field.getType());
1803         }
1804 
1805         public MemberSignature(Constructor<?> cons) {
1806             member = cons;
1807             name = cons.getName();
1808             signature = getMethodSignature(
1809                 cons.getParameterTypes(), Void.TYPE);
1810         }
1811 
1812         public MemberSignature(Method meth) {
1813             member = meth;
1814             name = meth.getName();
1815             signature = getMethodSignature(
1816                 meth.getParameterTypes(), meth.getReturnType());
1817         }
1818     }
1819 
1820     /**
1821      * Class for setting and retrieving serializable field values in batch.
1822      */
1823     // REMIND: dynamically generate these?
1824     private static class FieldReflector {
1825 
1826         /** handle for performing unsafe operations */
1827         private static final Unsafe unsafe = Unsafe.getUnsafe();
1828 
1829         /** fields to operate on */
1830         private final ObjectStreamField[] fields;
1831         /** number of primitive fields */
1832         private final int numPrimFields;
1833         /** unsafe field keys for reading fields - may contain dupes */
1834         private final long[] readKeys;
1835         /** unsafe fields keys for writing fields - no dupes */
1836         private final long[] writeKeys;
1837         /** field data offsets */
1838         private final int[] offsets;
1839         /** field type codes */
1840         private final char[] typeCodes;
1841         /** field types */
1842         private final Class<?>[] types;
1843 
1844         /**
1845          * Constructs FieldReflector capable of setting/getting values from the
1846          * subset of fields whose ObjectStreamFields contain non-null
1847          * reflective Field objects.  ObjectStreamFields with null Fields are
1848          * treated as filler, for which get operations return default values
1849          * and set operations discard given values.
1850          */
1851         FieldReflector(ObjectStreamField[] fields) {
1852             this.fields = fields;
1853             int nfields = fields.length;
1854             readKeys = new long[nfields];
1855             writeKeys = new long[nfields];
1856             offsets = new int[nfields];
1857             typeCodes = new char[nfields];
1858             ArrayList<Class<?>> typeList = new ArrayList<>();
1859             Set<Long> usedKeys = new HashSet<>();
1860 
1861 
1862             for (int i = 0; i < nfields; i++) {
1863                 ObjectStreamField f = fields[i];
1864                 Field rf = f.getField();
1865                 long key = (rf != null) ?
1866                     unsafe.objectFieldOffset(rf) : Unsafe.INVALID_FIELD_OFFSET;
1867                 readKeys[i] = key;
1868                 writeKeys[i] = usedKeys.add(key) ?
1869                     key : Unsafe.INVALID_FIELD_OFFSET;
1870                 offsets[i] = f.getOffset();
1871                 typeCodes[i] = f.getTypeCode();
1872                 if (!f.isPrimitive()) {
1873                     typeList.add((rf != null) ? rf.getType() : null);
1874                 }
1875             }
1876 
1877             types = typeList.toArray(new Class<?>[typeList.size()]);
1878             numPrimFields = nfields - types.length;
1879         }
1880 
1881         /**
1882          * Returns list of ObjectStreamFields representing fields operated on
1883          * by this reflector.  The shared/unshared values and Field objects
1884          * contained by ObjectStreamFields in the list reflect their bindings
1885          * to locally defined serializable fields.
1886          */
1887         ObjectStreamField[] getFields() {
1888             return fields;
1889         }
1890 
1891         /**
1892          * Fetches the serializable primitive field values of object obj and
1893          * marshals them into byte array buf starting at offset 0.  The caller
1894          * is responsible for ensuring that obj is of the proper type.
1895          */
1896         void getPrimFieldValues(Object obj, byte[] buf) {
1897             if (obj == null) {
1898                 throw new NullPointerException();
1899             }
1900             /* assuming checkDefaultSerialize() has been called on the class
1901              * descriptor this FieldReflector was obtained from, no field keys
1902              * in array should be equal to Unsafe.INVALID_FIELD_OFFSET.
1903              */
1904             for (int i = 0; i < numPrimFields; i++) {
1905                 long key = readKeys[i];
1906                 int off = offsets[i];
1907                 switch (typeCodes[i]) {
1908                     case 'Z':
1909                         Bits.putBoolean(buf, off, unsafe.getBoolean(obj, key));
1910                         break;
1911 
1912                     case 'B':
1913                         buf[off] = unsafe.getByte(obj, key);
1914                         break;
1915 
1916                     case 'C':
1917                         Bits.putChar(buf, off, unsafe.getChar(obj, key));
1918                         break;
1919 
1920                     case 'S':
1921                         Bits.putShort(buf, off, unsafe.getShort(obj, key));
1922                         break;
1923 
1924                     case 'I':
1925                         Bits.putInt(buf, off, unsafe.getInt(obj, key));
1926                         break;
1927 
1928                     case 'F':
1929                         Bits.putFloat(buf, off, unsafe.getFloat(obj, key));
1930                         break;
1931 
1932                     case 'J':
1933                         Bits.putLong(buf, off, unsafe.getLong(obj, key));
1934                         break;
1935 
1936                     case 'D':
1937                         Bits.putDouble(buf, off, unsafe.getDouble(obj, key));
1938                         break;
1939 
1940                     default:
1941                         throw new InternalError();
1942                 }
1943             }
1944         }
1945 
1946         /**
1947          * Sets the serializable primitive fields of object obj using values
1948          * unmarshalled from byte array buf starting at offset 0.  The caller
1949          * is responsible for ensuring that obj is of the proper type.
1950          */
1951         void setPrimFieldValues(Object obj, byte[] buf) {
1952             if (obj == null) {
1953                 throw new NullPointerException();
1954             }
1955             for (int i = 0; i < numPrimFields; i++) {
1956                 long key = writeKeys[i];
1957                 if (key == Unsafe.INVALID_FIELD_OFFSET) {
1958                     continue;           // discard value
1959                 }
1960                 int off = offsets[i];
1961                 switch (typeCodes[i]) {
1962                     case 'Z':
1963                         unsafe.putBoolean(obj, key, Bits.getBoolean(buf, off));
1964                         break;
1965 
1966                     case 'B':
1967                         unsafe.putByte(obj, key, buf[off]);
1968                         break;
1969 
1970                     case 'C':
1971                         unsafe.putChar(obj, key, Bits.getChar(buf, off));
1972                         break;
1973 
1974                     case 'S':
1975                         unsafe.putShort(obj, key, Bits.getShort(buf, off));
1976                         break;
1977 
1978                     case 'I':
1979                         unsafe.putInt(obj, key, Bits.getInt(buf, off));
1980                         break;
1981 
1982                     case 'F':
1983                         unsafe.putFloat(obj, key, Bits.getFloat(buf, off));
1984                         break;
1985 
1986                     case 'J':
1987                         unsafe.putLong(obj, key, Bits.getLong(buf, off));
1988                         break;
1989 
1990                     case 'D':
1991                         unsafe.putDouble(obj, key, Bits.getDouble(buf, off));
1992                         break;
1993 
1994                     default:
1995                         throw new InternalError();
1996                 }
1997             }
1998         }
1999 
2000         /**
2001          * Fetches the serializable object field values of object obj and
2002          * stores them in array vals starting at offset 0.  The caller is
2003          * responsible for ensuring that obj is of the proper type.
2004          */
2005         void getObjFieldValues(Object obj, Object[] vals) {
2006             if (obj == null) {
2007                 throw new NullPointerException();
2008             }
2009             /* assuming checkDefaultSerialize() has been called on the class
2010              * descriptor this FieldReflector was obtained from, no field keys
2011              * in array should be equal to Unsafe.INVALID_FIELD_OFFSET.
2012              */
2013             for (int i = numPrimFields; i < fields.length; i++) {
2014                 switch (typeCodes[i]) {
2015                     case 'L':
2016                     case '[':
2017                         vals[offsets[i]] = unsafe.getObject(obj, readKeys[i]);
2018                         break;
2019 
2020                     default:
2021                         throw new InternalError();
2022                 }
2023             }
2024         }
2025 
2026         /**
2027          * Sets the serializable object fields of object obj using values from
2028          * array vals starting at offset 0.  The caller is responsible for
2029          * ensuring that obj is of the proper type; however, attempts to set a
2030          * field with a value of the wrong type will trigger an appropriate
2031          * ClassCastException.
2032          */
2033         void setObjFieldValues(Object obj, Object[] vals) {
2034             if (obj == null) {
2035                 throw new NullPointerException();
2036             }
2037             for (int i = numPrimFields; i < fields.length; i++) {
2038                 long key = writeKeys[i];
2039                 if (key == Unsafe.INVALID_FIELD_OFFSET) {
2040                     continue;           // discard value
2041                 }
2042                 switch (typeCodes[i]) {
2043                     case 'L':
2044                     case '[':
2045                         Object val = vals[offsets[i]];
2046                         if (val != null &&
2047                             !types[i - numPrimFields].isInstance(val))
2048                         {
2049                             Field f = fields[i].getField();
2050                             throw new ClassCastException(
2051                                 "cannot assign instance of " +
2052                                 val.getClass().getName() + " to field " +
2053                                 f.getDeclaringClass().getName() + "." +
2054                                 f.getName() + " of type " +
2055                                 f.getType().getName() + " in instance of " +
2056                                 obj.getClass().getName());
2057                         }
2058                         unsafe.putObject(obj, key, val);
2059                         break;
2060 
2061                     default:
2062                         throw new InternalError();
2063                 }
2064             }
2065         }
2066     }
2067 
2068     /**
2069      * Matches given set of serializable fields with serializable fields
2070      * described by the given local class descriptor, and returns a
2071      * FieldReflector instance capable of setting/getting values from the
2072      * subset of fields that match (non-matching fields are treated as filler,
2073      * for which get operations return default values and set operations
2074      * discard given values).  Throws InvalidClassException if unresolvable
2075      * type conflicts exist between the two sets of fields.
2076      */
2077     private static FieldReflector getReflector(ObjectStreamField[] fields,
2078                                                ObjectStreamClass localDesc)
2079         throws InvalidClassException
2080     {
2081         // class irrelevant if no fields
2082         Class<?> cl = (localDesc != null && fields.length > 0) ?
2083             localDesc.cl : null;
2084         processQueue(Caches.reflectorsQueue, Caches.reflectors);
2085         FieldReflectorKey key = new FieldReflectorKey(cl, fields,
2086                                                       Caches.reflectorsQueue);
2087         Reference<?> ref = Caches.reflectors.get(key);
2088         Object entry = null;
2089         if (ref != null) {
2090             entry = ref.get();
2091         }
2092         EntryFuture future = null;
2093         if (entry == null) {
2094             EntryFuture newEntry = new EntryFuture();
2095             Reference<?> newRef = new SoftReference<>(newEntry);
2096             do {
2097                 if (ref != null) {
2098                     Caches.reflectors.remove(key, ref);
2099                 }
2100                 ref = Caches.reflectors.putIfAbsent(key, newRef);
2101                 if (ref != null) {
2102                     entry = ref.get();
2103                 }
2104             } while (ref != null && entry == null);
2105             if (entry == null) {
2106                 future = newEntry;
2107             }
2108         }
2109 
2110         if (entry instanceof FieldReflector) {  // check common case first
2111             return (FieldReflector) entry;
2112         } else if (entry instanceof EntryFuture) {
2113             entry = ((EntryFuture) entry).get();
2114         } else if (entry == null) {
2115             try {
2116                 entry = new FieldReflector(matchFields(fields, localDesc));
2117             } catch (Throwable th) {
2118                 entry = th;
2119             }
2120             future.set(entry);
2121             Caches.reflectors.put(key, new SoftReference<Object>(entry));
2122         }
2123 
2124         if (entry instanceof FieldReflector) {
2125             return (FieldReflector) entry;
2126         } else if (entry instanceof InvalidClassException) {
2127             throw (InvalidClassException) entry;
2128         } else if (entry instanceof RuntimeException) {
2129             throw (RuntimeException) entry;
2130         } else if (entry instanceof Error) {
2131             throw (Error) entry;
2132         } else {
2133             throw new InternalError("unexpected entry: " + entry);
2134         }
2135     }
2136 
2137     /**
2138      * FieldReflector cache lookup key.  Keys are considered equal if they
2139      * refer to the same class and equivalent field formats.
2140      */
2141     private static class FieldReflectorKey extends WeakReference<Class<?>> {
2142 
2143         private final String sigs;
2144         private final int hash;
2145         private final boolean nullClass;
2146 
2147         FieldReflectorKey(Class<?> cl, ObjectStreamField[] fields,
2148                           ReferenceQueue<Class<?>> queue)
2149         {
2150             super(cl, queue);
2151             nullClass = (cl == null);
2152             StringBuilder sbuf = new StringBuilder();
2153             for (int i = 0; i < fields.length; i++) {
2154                 ObjectStreamField f = fields[i];
2155                 sbuf.append(f.getName()).append(f.getSignature());
2156             }
2157             sigs = sbuf.toString();
2158             hash = System.identityHashCode(cl) + sigs.hashCode();
2159         }
2160 
2161         public int hashCode() {
2162             return hash;
2163         }
2164 
2165         public boolean equals(Object obj) {
2166             if (obj == this) {
2167                 return true;
2168             }
2169 
2170             if (obj instanceof FieldReflectorKey) {
2171                 FieldReflectorKey other = (FieldReflectorKey) obj;
2172                 Class<?> referent;
2173                 return (nullClass ? other.nullClass
2174                                   : ((referent = get()) != null) &&
2175                                     (referent == other.get())) &&
2176                     sigs.equals(other.sigs);
2177             } else {
2178                 return false;
2179             }
2180         }
2181     }
2182 
2183     /**
2184      * Matches given set of serializable fields with serializable fields
2185      * obtained from the given local class descriptor (which contain bindings
2186      * to reflective Field objects).  Returns list of ObjectStreamFields in
2187      * which each ObjectStreamField whose signature matches that of a local
2188      * field contains a Field object for that field; unmatched
2189      * ObjectStreamFields contain null Field objects.  Shared/unshared settings
2190      * of the returned ObjectStreamFields also reflect those of matched local
2191      * ObjectStreamFields.  Throws InvalidClassException if unresolvable type
2192      * conflicts exist between the two sets of fields.
2193      */
2194     private static ObjectStreamField[] matchFields(ObjectStreamField[] fields,
2195                                                    ObjectStreamClass localDesc)
2196         throws InvalidClassException
2197     {
2198         ObjectStreamField[] localFields = (localDesc != null) ?
2199             localDesc.fields : NO_FIELDS;
2200 
2201         /*
2202          * Even if fields == localFields, we cannot simply return localFields
2203          * here.  In previous implementations of serialization,
2204          * ObjectStreamField.getType() returned Object.class if the
2205          * ObjectStreamField represented a non-primitive field and belonged to
2206          * a non-local class descriptor.  To preserve this (questionable)
2207          * behavior, the ObjectStreamField instances returned by matchFields
2208          * cannot report non-primitive types other than Object.class; hence
2209          * localFields cannot be returned directly.
2210          */
2211 
2212         ObjectStreamField[] matches = new ObjectStreamField[fields.length];
2213         for (int i = 0; i < fields.length; i++) {
2214             ObjectStreamField f = fields[i], m = null;
2215             for (int j = 0; j < localFields.length; j++) {
2216                 ObjectStreamField lf = localFields[j];
2217                 if (f.getName().equals(lf.getName())) {
2218                     if ((f.isPrimitive() || lf.isPrimitive()) &&
2219                         f.getTypeCode() != lf.getTypeCode())
2220                     {
2221                         throw new InvalidClassException(localDesc.name,
2222                             "incompatible types for field " + f.getName());
2223                     }
2224                     if (lf.getField() != null) {
2225                         m = new ObjectStreamField(
2226                             lf.getField(), lf.isUnshared(), false);
2227                     } else {
2228                         m = new ObjectStreamField(
2229                             lf.getName(), lf.getSignature(), lf.isUnshared());
2230                     }
2231                 }
2232             }
2233             if (m == null) {
2234                 m = new ObjectStreamField(
2235                     f.getName(), f.getSignature(), false);
2236             }
2237             m.setOffset(f.getOffset());
2238             matches[i] = m;
2239         }
2240         return matches;
2241     }
2242 
2243     /**
2244      * Removes from the specified map any keys that have been enqueued
2245      * on the specified reference queue.
2246      */
2247     static void processQueue(ReferenceQueue<Class<?>> queue,
2248                              ConcurrentMap<? extends
2249                              WeakReference<Class<?>>, ?> map)
2250     {
2251         Reference<? extends Class<?>> ref;
2252         while((ref = queue.poll()) != null) {
2253             map.remove(ref);
2254         }
2255     }
2256 
2257     /**
2258      *  Weak key for Class objects.
2259      *
2260      **/
2261     static class WeakClassKey extends WeakReference<Class<?>> {
2262         /**
2263          * saved value of the referent's identity hash code, to maintain
2264          * a consistent hash code after the referent has been cleared
2265          */
2266         private final int hash;
2267 
2268         /**
2269          * Create a new WeakClassKey to the given object, registered
2270          * with a queue.
2271          */
2272         WeakClassKey(Class<?> cl, ReferenceQueue<Class<?>> refQueue) {
2273             super(cl, refQueue);
2274             hash = System.identityHashCode(cl);
2275         }
2276 
2277         /**
2278          * Returns the identity hash code of the original referent.
2279          */
2280         public int hashCode() {
2281             return hash;
2282         }
2283 
2284         /**
2285          * Returns true if the given object is this identical
2286          * WeakClassKey instance, or, if this object's referent has not
2287          * been cleared, if the given object is another WeakClassKey
2288          * instance with the identical non-null referent as this one.
2289          */
2290         public boolean equals(Object obj) {
2291             if (obj == this) {
2292                 return true;
2293             }
2294 
2295             if (obj instanceof WeakClassKey) {
2296                 Object referent = get();
2297                 return (referent != null) &&
2298                        (referent == ((WeakClassKey) obj).get());
2299             } else {
2300                 return false;
2301             }
2302         }
2303     }
2304 }