content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.io;
  
  import java.io.ObjectStreamClass.WeakClassKey;
  import java.lang.ref.ReferenceQueue;
  import java.lang.reflect.Array;
  import java.lang.reflect.Modifier;
  import java.lang.reflect.Proxy;
  import java.security.AccessControlContext;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.security.PrivilegedActionException;
  import java.security.PrivilegedExceptionAction;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.atomic.AtomicBoolean;
  import static java.io.ObjectStreamClass.processQueue;
  import sun.reflect.misc.ReflectUtil;
  import dalvik.system.VMStack;
  
  /**
   * An ObjectInputStream deserializes primitive data and objects previously
   * written using an ObjectOutputStream.
   *
   * <p>ObjectOutputStream and ObjectInputStream can provide an application with
   * persistent storage for graphs of objects when used with a FileOutputStream
   * and FileInputStream respectively.  ObjectInputStream is used to recover
   * those objects previously serialized. Other uses include passing objects
   * between hosts using a socket stream or for marshaling and unmarshaling
   * arguments and parameters in a remote communication system.
   *
   * <p>ObjectInputStream ensures that the types of all objects in the graph
   * created from the stream match the classes present in the Java Virtual
   * Machine.  Classes are loaded as required using the standard mechanisms.
   *
   * <p>Only objects that support the java.io.Serializable or
   * java.io.Externalizable interface can be read from streams.
   *
   * <p>The method <code>readObject</code> is used to read an object from the
   * stream.  Java's safe casting should be used to get the desired type.  In
   * Java, strings and arrays are objects and are treated as objects during
   * serialization. When read they need to be cast to the expected type.
   *
   * <p>Primitive data types can be read from the stream using the appropriate
   * method on DataInput.
   *
   * <p>The default deserialization mechanism for objects restores the contents
   * of each field to the value and type it had when it was written.  Fields
   * declared as transient or static are ignored by the deserialization process.
   * References to other objects cause those objects to be read from the stream
   * as necessary.  Graphs of objects are restored correctly using a reference
   * sharing mechanism.  New objects are always allocated when deserializing,
   * which prevents existing objects from being overwritten.
   *
   * <p>Reading an object is analogous to running the constructors of a new
   * object.  Memory is allocated for the object and initialized to zero (NULL).
   * No-arg constructors are invoked for the non-serializable classes and then
   * the fields of the serializable classes are restored from the stream starting
   * with the serializable class closest to java.lang.object and finishing with
   * the object's most specific class.
   *
   * <p>For example to read from a stream as written by the example in
   * ObjectOutputStream:
   * <br>
   * <pre>
   *      FileInputStream fis = new FileInputStream("t.tmp");
   *      ObjectInputStream ois = new ObjectInputStream(fis);
   *
   *      int i = ois.readInt();
   *      String today = (String) ois.readObject();
   *      Date date = (Date) ois.readObject();
   *
   *      ois.close();
   * </pre>
   *
   * <p>Classes control how they are serialized by implementing either the
   * java.io.Serializable or java.io.Externalizable interfaces.
   *
   * <p>Implementing the Serializable interface allows object serialization to
   * save and restore the entire state of the object and it allows classes to
   * evolve between the time the stream is written and the time it is read.  It
   * automatically traverses references between objects, saving and restoring
   * entire graphs.
   *
   * <p>Serializable classes that require special handling during the
   * serialization and deserialization process should implement the following
   * methods:
   *
   * <pre>
   * private void writeObject(java.io.ObjectOutputStream stream)
   *     throws IOException;
   * private void readObject(java.io.ObjectInputStream stream)
   *     throws IOException, ClassNotFoundException;
   * private void readObjectNoData()
   *     throws ObjectStreamException;
   * </pre>
   *
   * <p>The readObject method is responsible for reading and restoring the state
   * of the object for its particular class using data written to the stream by
   * the corresponding writeObject method.  The method does not need to concern
   * itself with the state belonging to its superclasses or subclasses.  State is
   * restored by reading data from the ObjectInputStream for the individual
   * fields and making assignments to the appropriate fields of the object.
   * Reading primitive data types is supported by DataInput.
   *
   * <p>Any attempt to read object data which exceeds the boundaries of the
   * custom data written by the corresponding writeObject method will cause an
   * OptionalDataException to be thrown with an eof field value of true.
   * Non-object reads which exceed the end of the allotted data will reflect the
   * end of data in the same way that they would indicate the end of the stream:
   * bytewise reads will return -1 as the byte read or number of bytes read, and
   * primitive reads will throw EOFExceptions.  If there is no corresponding
   * writeObject method, then the end of default serialized data marks the end of
   * the allotted data.
   *
   * <p>Primitive and object read calls issued from within a readExternal method
   * behave in the same manner--if the stream is already positioned at the end of
   * data written by the corresponding writeExternal method, object reads will
   * throw OptionalDataExceptions with eof set to true, bytewise reads will
   * return -1, and primitive reads will throw EOFExceptions.  Note that this
   * behavior does not hold for streams written with the old
   * <code>ObjectStreamConstants.PROTOCOL_VERSION_1</code> protocol, in which the
   * end of data written by writeExternal methods is not demarcated, and hence
   * cannot be detected.
   *
   * <p>The readObjectNoData method is responsible for initializing the state of
   * the object for its particular class in the event that the serialization
   * stream does not list the given class as a superclass of the object being
   * deserialized.  This may occur in cases where the receiving party uses a
   * different version of the deserialized instance's class than the sending
   * party, and the receiver's version extends classes that are not extended by
   * the sender's version.  This may also occur if the serialization stream has
   * been tampered; hence, readObjectNoData is useful for initializing
   * deserialized objects properly despite a "hostile" or incomplete source
   * stream.
   *
   * <p>Serialization does not read or assign values to the fields of any object
   * that does not implement the java.io.Serializable interface.  Subclasses of
   * Objects that are not serializable can be serializable. In this case the
   * non-serializable class must have a no-arg constructor to allow its fields to
   * be initialized.  In this case it is the responsibility of the subclass to
   * save and restore the state of the non-serializable class. It is frequently
   * the case that the fields of that class are accessible (public, package, or
   * protected) or that there are get and set methods that can be used to restore
   * the state.
   *
   * <p>Any exception that occurs while deserializing an object will be caught by
   * the ObjectInputStream and abort the reading process.
   *
   * <p>Implementing the Externalizable interface allows the object to assume
   * complete control over the contents and format of the object's serialized
   * form.  The methods of the Externalizable interface, writeExternal and
   * readExternal, are called to save and restore the objects state.  When
   * implemented by a class they can write and read their own state using all of
   * the methods of ObjectOutput and ObjectInput.  It is the responsibility of
   * the objects to handle any versioning that occurs.
   *
   * <p>Enum constants are deserialized differently than ordinary serializable or
   * externalizable objects.  The serialized form of an enum constant consists
   * solely of its name; field values of the constant are not transmitted.  To
   * deserialize an enum constant, ObjectInputStream reads the constant name from
   * the stream; the deserialized constant is then obtained by calling the static
   * method <code>Enum.valueOf(Class, String)</code> with the enum constant's
   * base type and the received constant name as arguments.  Like other
   * serializable or externalizable objects, enum constants can function as the
   * targets of back references appearing subsequently in the serialization
   * stream.  The process by which enum constants are deserialized cannot be
   * customized: any class-specific readObject, readObjectNoData, and readResolve
   * methods defined by enum types are ignored during deserialization.
   * Similarly, any serialPersistentFields or serialVersionUID field declarations
   * are also ignored--all enum types have a fixed serialVersionUID of 0L.
   *
   * @author      Mike Warres
   * @author      Roger Riggs
   * @see DataInput
   * @see ObjectOutputStream
   * @see Serializable
   * @see <a href="../../../platform/serialization/spec/input.html"> Object Serialization Specification, Section 3, Object Input Classes</a>
   * @since   JDK1.1
   */
  public class ObjectInputStream
      extends InputStream implements ObjectInput, ObjectStreamConstants
  {
      /** handle value representing null */
      private static final int NULL_HANDLE = -1;
  
      /** marker for unshared objects in internal handle table */
      private static final Object unsharedMarker = new Object();
  
      /** table mapping primitive type names to corresponding class objects */
      private static final HashMap<String, Class<?>> primClasses
          = new HashMap<>(8, 1.0F);
      static {
          primClasses.put("boolean", boolean.class);
          primClasses.put("byte", byte.class);
          primClasses.put("char", char.class);
          primClasses.put("short", short.class);
          primClasses.put("int", int.class);
          primClasses.put("long", long.class);
          primClasses.put("float", float.class);
          primClasses.put("double", double.class);
          primClasses.put("void", void.class);
      }
  
      private static class Caches {
          /** cache of subclass security audit results */
          static final ConcurrentMap<WeakClassKey,Boolean> subclassAudits =
              new ConcurrentHashMap<>();
  
          /** queue for WeakReferences to audited subclasses */
          static final ReferenceQueue<Class<?>> subclassAuditsQueue =
              new ReferenceQueue<>();
      }
  
      // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
      /*
      static {
          /* Setup access so sun.misc can invoke package private functions. *
          sun.misc.SharedSecrets.setJavaOISAccess(new JavaOISAccess() {
              public void setObjectInputFilter(ObjectInputStream stream, ObjectInputFilter filter) {
                  stream.setInternalObjectInputFilter(filter);
              }
  
              public ObjectInputFilter getObjectInputFilter(ObjectInputStream stream) {
                  return stream.getInternalObjectInputFilter();
              }
          });
      }
  
      /*
       * Separate class to defer initialization of logging until needed.
       *
      private static class Logging {
  
          /*
           * Logger for ObjectInputFilter results.
           * Setup the filter logger if it is set to INFO or WARNING.
           * (Assuming it will not change).
           *
          private static final PlatformLogger traceLogger;
          private static final PlatformLogger infoLogger;
          static {
              PlatformLogger filterLog = PlatformLogger.getLogger("java.io.serialization");
              infoLogger = (filterLog != null &&
                  filterLog.isLoggable(PlatformLogger.Level.INFO)) ? filterLog : null;
              traceLogger = (filterLog != null &&
                  filterLog.isLoggable(PlatformLogger.Level.FINER)) ? filterLog : null;
          }
      }
      */
  
      /** filter stream for handling block data conversion */
      private final BlockDataInputStream bin;
      /** validation callback list */
      private final ValidationList vlist;
      /** recursion depth */
      // Android-changed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
      // private long depth;
      private int depth;
      // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
      // /** Total number of references to any type of object, class, enum, proxy, etc. */
      // private long totalObjectRefs;
      /** whether stream is closed */
      private boolean closed;
  
      /** wire handle -> obj/exception map */
      private final HandleTable handles;
      /** scratch field for passing handle values up/down call stack */
      private int passHandle = NULL_HANDLE;
      /** flag set when at end of field value block with no TC_ENDBLOCKDATA */
      private boolean defaultDataEnd = false;
  
      /** buffer for reading primitive field values */
      private byte[] primVals;
  
      /** if true, invoke readObjectOverride() instead of readObject() */
      private final boolean enableOverride;
      /** if true, invoke resolveObject() */
      private boolean enableResolve;
  
      /**
       * Context during upcalls to class-defined readObject methods; holds
       * object currently being deserialized and descriptor for current class.
       * Null when not during readObject upcall.
       */
      private SerialCallbackContext curContext;
  
      // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
      /**
       * Filter of class descriptors and classes read from the stream;
       * may be null.
       *
      private ObjectInputFilter serialFilter;
      */
  
      /**
       * Creates an ObjectInputStream that reads from the specified InputStream.
       * A serialization stream header is read from the stream and verified.
       * This constructor will block until the corresponding ObjectOutputStream
       * has written and flushed the header.
       *
       * <p>If a security manager is installed, this constructor will check for
       * the "enableSubclassImplementation" SerializablePermission when invoked
       * directly or indirectly by the constructor of a subclass which overrides
       * the ObjectInputStream.readFields or ObjectInputStream.readUnshared
       * methods.
       *
       * @param   in input stream to read from
       * @throws  StreamCorruptedException if the stream header is incorrect
       * @throws  IOException if an I/O error occurs while reading stream header
       * @throws  SecurityException if untrusted subclass illegally overrides
       *          security-sensitive methods
       * @throws  NullPointerException if <code>in</code> is <code>null</code>
       * @see     ObjectInputStream#ObjectInputStream()
       * @see     ObjectInputStream#readFields()
       * @see     ObjectOutputStream#ObjectOutputStream(OutputStream)
       */
      public ObjectInputStream(InputStream in) throws IOException {
          verifySubclass();
          bin = new BlockDataInputStream(in);
          handles = new HandleTable(10);
          vlist = new ValidationList();
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // serialFilter = ObjectInputFilter.Config.getSerialFilter();
          enableOverride = false;
          readStreamHeader();
          bin.setBlockDataMode(true);
      }
  
      /**
       * Provide a way for subclasses that are completely reimplementing
       * ObjectInputStream to not have to allocate private data just used by this
       * implementation of ObjectInputStream.
       *
       * <p>If there is a security manager installed, this method first calls the
       * security manager's <code>checkPermission</code> method with the
       * <code>SerializablePermission("enableSubclassImplementation")</code>
       * permission to ensure it's ok to enable subclassing.
       *
       * @throws  SecurityException if a security manager exists and its
       *          <code>checkPermission</code> method denies enabling
       *          subclassing.
       * @throws  IOException if an I/O error occurs while creating this stream
       * @see SecurityManager#checkPermission
       * @see SerializablePermission
       */
      protected ObjectInputStream() throws IOException, SecurityException {
          SecurityManager sm = System.getSecurityManager();
          if (sm != null) {
              sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
          }
          bin = null;
          handles = null;
          vlist = null;
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // serialFilter = ObjectInputFilter.Config.getSerialFilter();
          enableOverride = true;
      }
  
      /**
       * Read an object from the ObjectInputStream.  The class of the object, the
       * signature of the class, and the values of the non-transient and
       * non-static fields of the class and all of its supertypes are read.
       * Default deserializing for a class can be overridden using the writeObject
       * and readObject methods.  Objects referenced by this object are read
       * transitively so that a complete equivalent graph of objects is
       * reconstructed by readObject.
       *
       * <p>The root object is completely restored when all of its fields and the
       * objects it references are completely restored.  At this point the object
       * validation callbacks are executed in order based on their registered
       * priorities. The callbacks are registered by objects (in the readObject
       * special methods) as they are individually restored.
       *
       * <p>Exceptions are thrown for problems with the InputStream and for
       * classes that should not be deserialized.  All exceptions are fatal to
       * the InputStream and leave it in an indeterminate state; it is up to the
       * caller to ignore or recover the stream state.
       *
       * @throws  ClassNotFoundException Class of a serialized object cannot be
       *          found.
       * @throws  InvalidClassException Something is wrong with a class used by
       *          serialization.
       * @throws  StreamCorruptedException Control information in the
       *          stream is inconsistent.
       * @throws  OptionalDataException Primitive data was found in the
       *          stream instead of objects.
       * @throws  IOException Any of the usual Input/Output related exceptions.
       */
      public final Object readObject()
          throws IOException, ClassNotFoundException
      {
          if (enableOverride) {
              return readObjectOverride();
          }
  
          // if nested read, passHandle contains handle of enclosing object
          int outerHandle = passHandle;
          try {
              Object obj = readObject0(false);
              handles.markDependency(outerHandle, passHandle);
              ClassNotFoundException ex = handles.lookupException(passHandle);
              if (ex != null) {
                  throw ex;
              }
              if (depth == 0) {
                  vlist.doCallbacks();
              }
              return obj;
          } finally {
              passHandle = outerHandle;
              if (closed && depth == 0) {
                  clear();
              }
          }
      }
  
      /**
       * This method is called by trusted subclasses of ObjectOutputStream that
       * constructed ObjectOutputStream using the protected no-arg constructor.
       * The subclass is expected to provide an override method with the modifier
       * "final".
       *
       * @return  the Object read from the stream.
       * @throws  ClassNotFoundException Class definition of a serialized object
       *          cannot be found.
       * @throws  OptionalDataException Primitive data was found in the stream
       *          instead of objects.
       * @throws  IOException if I/O errors occurred while reading from the
       *          underlying stream
       * @see #ObjectInputStream()
       * @see #readObject()
       * @since 1.2
       */
      protected Object readObjectOverride()
          throws IOException, ClassNotFoundException
      {
          return null;
      }
  
      /**
       * Reads an "unshared" object from the ObjectInputStream.  This method is
       * identical to readObject, except that it prevents subsequent calls to
       * readObject and readUnshared from returning additional references to the
       * deserialized instance obtained via this call.  Specifically:
       * <ul>
       *   <li>If readUnshared is called to deserialize a back-reference (the
       *       stream representation of an object which has been written
       *       previously to the stream), an ObjectStreamException will be
       *       thrown.
       *
       *   <li>If readUnshared returns successfully, then any subsequent attempts
       *       to deserialize back-references to the stream handle deserialized
       *       by readUnshared will cause an ObjectStreamException to be thrown.
       * </ul>
       * Deserializing an object via readUnshared invalidates the stream handle
       * associated with the returned object.  Note that this in itself does not
       * always guarantee that the reference returned by readUnshared is unique;
       * the deserialized object may define a readResolve method which returns an
       * object visible to other parties, or readUnshared may return a Class
       * object or enum constant obtainable elsewhere in the stream or through
       * external means. If the deserialized object defines a readResolve method
       * and the invocation of that method returns an array, then readUnshared
       * returns a shallow clone of that array; this guarantees that the returned
       * array object is unique and cannot be obtained a second time from an
       * invocation of readObject or readUnshared on the ObjectInputStream,
       * even if the underlying data stream has been manipulated.
       *
       * <p>ObjectInputStream subclasses which override this method can only be
       * constructed in security contexts possessing the
       * "enableSubclassImplementation" SerializablePermission; any attempt to
       * instantiate such a subclass without this permission will cause a
       * SecurityException to be thrown.
       *
       * @return  reference to deserialized object
       * @throws  ClassNotFoundException if class of an object to deserialize
       *          cannot be found
       * @throws  StreamCorruptedException if control information in the stream
       *          is inconsistent
       * @throws  ObjectStreamException if object to deserialize has already
       *          appeared in stream
       * @throws  OptionalDataException if primitive data is next in stream
       * @throws  IOException if an I/O error occurs during deserialization
       * @since   1.4
       */
      public Object readUnshared() throws IOException, ClassNotFoundException {
          // if nested read, passHandle contains handle of enclosing object
          int outerHandle = passHandle;
          try {
              Object obj = readObject0(true);
              handles.markDependency(outerHandle, passHandle);
              ClassNotFoundException ex = handles.lookupException(passHandle);
              if (ex != null) {
                  throw ex;
              }
              if (depth == 0) {
                  vlist.doCallbacks();
              }
              return obj;
          } finally {
              passHandle = outerHandle;
              if (closed && depth == 0) {
                  clear();
              }
          }
      }
  
      /**
       * Read the non-static and non-transient fields of the current class from
       * this stream.  This may only be called from the readObject method of the
       * class being deserialized. It will throw the NotActiveException if it is
       * called otherwise.
       *
       * @throws  ClassNotFoundException if the class of a serialized object
       *          could not be found.
       * @throws  IOException if an I/O error occurs.
       * @throws  NotActiveException if the stream is not currently reading
       *          objects.
       */
      public void defaultReadObject()
          throws IOException, ClassNotFoundException
      {
          SerialCallbackContext ctx = curContext;
          if (ctx == null) {
              throw new NotActiveException("not in call to readObject");
          }
          Object curObj = ctx.getObj();
          ObjectStreamClass curDesc = ctx.getDesc();
          bin.setBlockDataMode(false);
          defaultReadFields(curObj, curDesc);
          bin.setBlockDataMode(true);
          if (!curDesc.hasWriteObjectData()) {
              /*
               * Fix for 4360508: since stream does not contain terminating
               * TC_ENDBLOCKDATA tag, set flag so that reading code elsewhere
               * knows to simulate end-of-custom-data behavior.
               */
              defaultDataEnd = true;
          }
          ClassNotFoundException ex = handles.lookupException(passHandle);
          if (ex != null) {
              throw ex;
          }
      }
  
      /**
       * Reads the persistent fields from the stream and makes them available by
       * name.
       *
       * @return  the <code>GetField</code> object representing the persistent
       *          fields of the object being deserialized
       * @throws  ClassNotFoundException if the class of a serialized object
       *          could not be found.
       * @throws  IOException if an I/O error occurs.
       * @throws  NotActiveException if the stream is not currently reading
       *          objects.
       * @since 1.2
       */
      public GetField readFields()
          throws IOException, ClassNotFoundException
      {
          SerialCallbackContext ctx = curContext;
          if (ctx == null) {
              throw new NotActiveException("not in call to readObject");
          }
          Object curObj = ctx.getObj();
          ObjectStreamClass curDesc = ctx.getDesc();
          bin.setBlockDataMode(false);
          GetFieldImpl getField = new GetFieldImpl(curDesc);
          getField.readFields();
          bin.setBlockDataMode(true);
          if (!curDesc.hasWriteObjectData()) {
              /*
               * Fix for 4360508: since stream does not contain terminating
               * TC_ENDBLOCKDATA tag, set flag so that reading code elsewhere
               * knows to simulate end-of-custom-data behavior.
               */
              defaultDataEnd = true;
          }
  
          return getField;
      }
  
      /**
       * Register an object to be validated before the graph is returned.  While
       * similar to resolveObject these validations are called after the entire
       * graph has been reconstituted.  Typically, a readObject method will
       * register the object with the stream so that when all of the objects are
       * restored a final set of validations can be performed.
       *
       * @param   obj the object to receive the validation callback.
       * @param   prio controls the order of callbacks;zero is a good default.
       *          Use higher numbers to be called back earlier, lower numbers for
       *          later callbacks. Within a priority, callbacks are processed in
       *          no particular order.
       * @throws  NotActiveException The stream is not currently reading objects
       *          so it is invalid to register a callback.
       * @throws  InvalidObjectException The validation object is null.
       */
      public void registerValidation(ObjectInputValidation obj, int prio)
          throws NotActiveException, InvalidObjectException
      {
          if (depth == 0) {
              throw new NotActiveException("stream inactive");
          }
          vlist.register(obj, prio);
      }
  
      /**
       * Load the local class equivalent of the specified stream class
       * description.  Subclasses may implement this method to allow classes to
       * be fetched from an alternate source.
       *
       * <p>The corresponding method in <code>ObjectOutputStream</code> is
       * <code>annotateClass</code>.  This method will be invoked only once for
       * each unique class in the stream.  This method can be implemented by
       * subclasses to use an alternate loading mechanism but must return a
       * <code>Class</code> object. Once returned, if the class is not an array
       * class, its serialVersionUID is compared to the serialVersionUID of the
       * serialized class, and if there is a mismatch, the deserialization fails
       * and an {@link InvalidClassException} is thrown.
       *
       * <p>The default implementation of this method in
       * <code>ObjectInputStream</code> returns the result of calling
       * <pre>
       *     Class.forName(desc.getName(), false, loader)
       * </pre>
       * where <code>loader</code> is determined as follows: if there is a
       * method on the current thread's stack whose declaring class was
       * defined by a user-defined class loader (and was not a generated to
       * implement reflective invocations), then <code>loader</code> is class
       * loader corresponding to the closest such method to the currently
       * executing frame; otherwise, <code>loader</code> is
       * <code>null</code>. If this call results in a
       * <code>ClassNotFoundException</code> and the name of the passed
       * <code>ObjectStreamClass</code> instance is the Java language keyword
       * for a primitive type or void, then the <code>Class</code> object
       * representing that primitive type or void will be returned
       * (e.g., an <code>ObjectStreamClass</code> with the name
       * <code>"int"</code> will be resolved to <code>Integer.TYPE</code>).
       * Otherwise, the <code>ClassNotFoundException</code> will be thrown to
       * the caller of this method.
       *
       * @param   desc an instance of class <code>ObjectStreamClass</code>
       * @return  a <code>Class</code> object corresponding to <code>desc</code>
       * @throws  IOException any of the usual Input/Output exceptions.
       * @throws  ClassNotFoundException if class of a serialized object cannot
       *          be found.
       */
      protected Class<?> resolveClass(ObjectStreamClass desc)
          throws IOException, ClassNotFoundException
      {
          String name = desc.getName();
          try {
              return Class.forName(name, false, latestUserDefinedLoader());
          } catch (ClassNotFoundException ex) {
              Class<?> cl = primClasses.get(name);
              if (cl != null) {
                  return cl;
              } else {
                  throw ex;
              }
          }
      }
  
      /**
       * Returns a proxy class that implements the interfaces named in a proxy
       * class descriptor; subclasses may implement this method to read custom
       * data from the stream along with the descriptors for dynamic proxy
       * classes, allowing them to use an alternate loading mechanism for the
       * interfaces and the proxy class.
       *
       * <p>This method is called exactly once for each unique proxy class
       * descriptor in the stream.
       *
       * <p>The corresponding method in <code>ObjectOutputStream</code> is
       * <code>annotateProxyClass</code>.  For a given subclass of
       * <code>ObjectInputStream</code> that overrides this method, the
       * <code>annotateProxyClass</code> method in the corresponding subclass of
       * <code>ObjectOutputStream</code> must write any data or objects read by
       * this method.
       *
       * <p>The default implementation of this method in
       * <code>ObjectInputStream</code> returns the result of calling
       * <code>Proxy.getProxyClass</code> with the list of <code>Class</code>
       * objects for the interfaces that are named in the <code>interfaces</code>
       * parameter.  The <code>Class</code> object for each interface name
       * <code>i</code> is the value returned by calling
       * <pre>
       *     Class.forName(i, false, loader)
       * </pre>
       * where <code>loader</code> is that of the first non-<code>null</code>
       * class loader up the execution stack, or <code>null</code> if no
       * non-<code>null</code> class loaders are on the stack (the same class
       * loader choice used by the <code>resolveClass</code> method).  Unless any
       * of the resolved interfaces are non-public, this same value of
       * <code>loader</code> is also the class loader passed to
       * <code>Proxy.getProxyClass</code>; if non-public interfaces are present,
       * their class loader is passed instead (if more than one non-public
       * interface class loader is encountered, an
       * <code>IllegalAccessError</code> is thrown).
       * If <code>Proxy.getProxyClass</code> throws an
       * <code>IllegalArgumentException</code>, <code>resolveProxyClass</code>
       * will throw a <code>ClassNotFoundException</code> containing the
       * <code>IllegalArgumentException</code>.
       *
       * @param interfaces the list of interface names that were
       *                deserialized in the proxy class descriptor
       * @return  a proxy class for the specified interfaces
       * @throws        IOException any exception thrown by the underlying
       *                <code>InputStream</code>
       * @throws        ClassNotFoundException if the proxy class or any of the
       *                named interfaces could not be found
       * @see ObjectOutputStream#annotateProxyClass(Class)
       * @since 1.3
       */
      protected Class<?> resolveProxyClass(String[] interfaces)
          throws IOException, ClassNotFoundException
      {
          ClassLoader latestLoader = latestUserDefinedLoader();
          ClassLoader nonPublicLoader = null;
          boolean hasNonPublicInterface = false;
  
          // define proxy in class loader of non-public interface(s), if any
          Class<?>[] classObjs = new Class<?>[interfaces.length];
          for (int i = 0; i < interfaces.length; i++) {
              Class<?> cl = Class.forName(interfaces[i], false, latestLoader);
              if ((cl.getModifiers() & Modifier.PUBLIC) == 0) {
                  if (hasNonPublicInterface) {
                      if (nonPublicLoader != cl.getClassLoader()) {
                          throw new IllegalAccessError(
                              "conflicting non-public interface class loaders");
                      }
                  } else {
                      nonPublicLoader = cl.getClassLoader();
                      hasNonPublicInterface = true;
                  }
              }
              classObjs[i] = cl;
          }
          try {
              return Proxy.getProxyClass(
                  hasNonPublicInterface ? nonPublicLoader : latestLoader,
                  classObjs);
          } catch (IllegalArgumentException e) {
              throw new ClassNotFoundException(null, e);
          }
      }
  
      /**
       * This method will allow trusted subclasses of ObjectInputStream to
       * substitute one object for another during deserialization. Replacing
       * objects is disabled until enableResolveObject is called. The
       * enableResolveObject method checks that the stream requesting to resolve
       * object can be trusted. Every reference to serializable objects is passed
       * to resolveObject.  To insure that the private state of objects is not
       * unintentionally exposed only trusted streams may use resolveObject.
       *
       * <p>This method is called after an object has been read but before it is
       * returned from readObject.  The default resolveObject method just returns
       * the same object.
       *
       * <p>When a subclass is replacing objects it must insure that the
       * substituted object is compatible with every field where the reference
       * will be stored.  Objects whose type is not a subclass of the type of the
       * field or array element abort the serialization by raising an exception
       * and the object is not be stored.
       *
       * <p>This method is called only once when each object is first
       * encountered.  All subsequent references to the object will be redirected
       * to the new object.
       *
       * @param   obj object to be substituted
       * @return  the substituted object
       * @throws  IOException Any of the usual Input/Output exceptions.
       */
      protected Object resolveObject(Object obj) throws IOException {
          return obj;
      }
  
      /**
       * Enable the stream to allow objects read from the stream to be replaced.
       * When enabled, the resolveObject method is called for every object being
       * deserialized.
       *
       * <p>If <i>enable</i> is true, and there is a security manager installed,
       * this method first calls the security manager's
       * <code>checkPermission</code> method with the
       * <code>SerializablePermission("enableSubstitution")</code> permission to
       * ensure it's ok to enable the stream to allow objects read from the
       * stream to be replaced.
       *
       * @param   enable true for enabling use of <code>resolveObject</code> for
       *          every object being deserialized
       * @return  the previous setting before this method was invoked
       * @throws  SecurityException if a security manager exists and its
       *          <code>checkPermission</code> method denies enabling the stream
       *          to allow objects read from the stream to be replaced.
       * @see SecurityManager#checkPermission
       * @see SerializablePermission
       */
      protected boolean enableResolveObject(boolean enable)
          throws SecurityException
      {
          if (enable == enableResolve) {
              return enable;
          }
          if (enable) {
              SecurityManager sm = System.getSecurityManager();
              if (sm != null) {
                  sm.checkPermission(SUBSTITUTION_PERMISSION);
              }
          }
          enableResolve = enable;
          return !enableResolve;
      }
  
      /**
       * The readStreamHeader method is provided to allow subclasses to read and
       * verify their own stream headers. It reads and verifies the magic number
       * and version number.
       *
       * @throws  IOException if there are I/O errors while reading from the
       *          underlying <code>InputStream</code>
       * @throws  StreamCorruptedException if control information in the stream
       *          is inconsistent
       */
      protected void readStreamHeader()
          throws IOException, StreamCorruptedException
      {
          short s0 = bin.readShort();
          short s1 = bin.readShort();
          if (s0 != STREAM_MAGIC || s1 != STREAM_VERSION) {
              throw new StreamCorruptedException(
                  String.format("invalid stream header: %04X%04X", s0, s1));
          }
      }
  
      /**
       * Read a class descriptor from the serialization stream.  This method is
       * called when the ObjectInputStream expects a class descriptor as the next
       * item in the serialization stream.  Subclasses of ObjectInputStream may
       * override this method to read in class descriptors that have been written
       * in non-standard formats (by subclasses of ObjectOutputStream which have
       * overridden the <code>writeClassDescriptor</code> method).  By default,
       * this method reads class descriptors according to the format defined in
       * the Object Serialization specification.
       *
       * @return  the class descriptor read
       * @throws  IOException If an I/O error has occurred.
       * @throws  ClassNotFoundException If the Class of a serialized object used
       *          in the class descriptor representation cannot be found
       * @see ObjectOutputStream#writeClassDescriptor(ObjectStreamClass)
       * @since 1.3
       */
      protected ObjectStreamClass readClassDescriptor()
          throws IOException, ClassNotFoundException
      {
          ObjectStreamClass desc = new ObjectStreamClass();
          desc.readNonProxy(this);
          return desc;
      }
  
      /**
       * Reads a byte of data. This method will block if no input is available.
       *
       * @return  the byte read, or -1 if the end of the stream is reached.
       * @throws  IOException If an I/O error has occurred.
       */
      public int read() throws IOException {
          return bin.read();
      }
  
      /**
       * Reads into an array of bytes.  This method will block until some input
       * is available. Consider using java.io.DataInputStream.readFully to read
       * exactly 'length' bytes.
       *
       * @param   buf the buffer into which the data is read
       * @param   off the start offset of the data
       * @param   len the maximum number of bytes read
       * @return  the actual number of bytes read, -1 is returned when the end of
       *          the stream is reached.
       * @throws  IOException If an I/O error has occurred.
       * @see DataInputStream#readFully(byte[],int,int)
       */
      public int read(byte[] buf, int off, int len) throws IOException {
          if (buf == null) {
              throw new NullPointerException();
          }
          int endoff = off + len;
          if (off < 0 || len < 0 || endoff > buf.length || endoff < 0) {
              throw new IndexOutOfBoundsException();
          }
          return bin.read(buf, off, len, false);
      }
  
      /**
       * Returns the number of bytes that can be read without blocking.
       *
       * @return  the number of available bytes.
       * @throws  IOException if there are I/O errors while reading from the
       *          underlying <code>InputStream</code>
       */
      public int available() throws IOException {
          return bin.available();
      }
  
      /**
       * Closes the input stream. Must be called to release any resources
       * associated with the stream.
       *
       * @throws  IOException If an I/O error has occurred.
       */
      public void close() throws IOException {
          /*
           * Even if stream already closed, propagate redundant close to
           * underlying stream to stay consistent with previous implementations.
           */
          closed = true;
          if (depth == 0) {
              clear();
          }
          bin.close();
      }
  
      /**
       * Reads in a boolean.
       *
       * @return  the boolean read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public boolean readBoolean() throws IOException {
          return bin.readBoolean();
      }
  
      /**
       * Reads an 8 bit byte.
       *
       * @return  the 8 bit byte read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public byte readByte() throws IOException  {
          return bin.readByte();
      }
  
      /**
       * Reads an unsigned 8 bit byte.
       *
       * @return  the 8 bit byte read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public int readUnsignedByte()  throws IOException {
          return bin.readUnsignedByte();
      }
  
      /**
       * Reads a 16 bit char.
       *
       * @return  the 16 bit char read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public char readChar()  throws IOException {
          return bin.readChar();
      }
  
      /**
       * Reads a 16 bit short.
       *
       * @return  the 16 bit short read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public short readShort()  throws IOException {
          return bin.readShort();
      }
  
      /**
       * Reads an unsigned 16 bit short.
       *
       * @return  the 16 bit short read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public int readUnsignedShort() throws IOException {
          return bin.readUnsignedShort();
      }
  
      /**
       * Reads a 32 bit int.
       *
       * @return  the 32 bit integer read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public int readInt()  throws IOException {
          return bin.readInt();
      }
  
      /**
       * Reads a 64 bit long.
       *
       * @return  the read 64 bit long.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public long readLong()  throws IOException {
          return bin.readLong();
      }
  
      /**
       * Reads a 32 bit float.
       *
       * @return  the 32 bit float read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public float readFloat() throws IOException {
          return bin.readFloat();
      }
  
      /**
       * Reads a 64 bit double.
       *
       * @return  the 64 bit double read.
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public double readDouble() throws IOException {
          return bin.readDouble();
      }
  
      /**
       * Reads bytes, blocking until all bytes are read.
       *
       * @param   buf the buffer into which the data is read
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public void readFully(byte[] buf) throws IOException {
          bin.readFully(buf, 0, buf.length, false);
      }
  
      /**
       * Reads bytes, blocking until all bytes are read.
       *
       * @param   buf the buffer into which the data is read
       * @param   off the start offset of the data
       * @param   len the maximum number of bytes to read
       * @throws  EOFException If end of file is reached.
       * @throws  IOException If other I/O error has occurred.
       */
      public void readFully(byte[] buf, int off, int len) throws IOException {
          int endoff = off + len;
          if (off < 0 || len < 0 || endoff > buf.length || endoff < 0) {
              throw new IndexOutOfBoundsException();
          }
          bin.readFully(buf, off, len, false);
      }
  
      /**
       * Skips bytes.
       *
       * @param   len the number of bytes to be skipped
       * @return  the actual number of bytes skipped.
       * @throws  IOException If an I/O error has occurred.
       */
      public int skipBytes(int len) throws IOException {
          return bin.skipBytes(len);
      }
  
      /**
       * Reads in a line that has been terminated by a \n, \r, \r\n or EOF.
       *
       * @return  a String copy of the line.
       * @throws  IOException if there are I/O errors while reading from the
       *          underlying <code>InputStream</code>
       * @deprecated This method does not properly convert bytes to characters.
       *          see DataInputStream for the details and alternatives.
       */
      @Deprecated
      public String readLine() throws IOException {
          return bin.readLine();
      }
  
      /**
       * Reads a String in
       * <a href="DataInput.html#modified-utf-8">modified UTF-8</a>
       * format.
       *
       * @return  the String.
       * @throws  IOException if there are I/O errors while reading from the
       *          underlying <code>InputStream</code>
       * @throws  UTFDataFormatException if read bytes do not represent a valid
       *          modified UTF-8 encoding of a string
       */
      public String readUTF() throws IOException {
          return bin.readUTF();
      }
  
      // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
      // Removed ObjectInputFilter related methods.
  
      /**
       * Provide access to the persistent fields read from the input stream.
       */
      public static abstract class GetField {
  
          /**
           * Get the ObjectStreamClass that describes the fields in the stream.
           *
           * @return  the descriptor class that describes the serializable fields
           */
          public abstract ObjectStreamClass getObjectStreamClass();
  
          /**
           * Return true if the named field is defaulted and has no value in this
           * stream.
           *
           * @param  name the name of the field
           * @return true, if and only if the named field is defaulted
           * @throws IOException if there are I/O errors while reading from
           *         the underlying <code>InputStream</code>
           * @throws IllegalArgumentException if <code>name</code> does not
           *         correspond to a serializable field
           */
          public abstract boolean defaulted(String name) throws IOException;
  
          /**
           * Get the value of the named boolean field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>boolean</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract boolean get(String name, boolean val)
              throws IOException;
  
          /**
           * Get the value of the named byte field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>byte</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract byte get(String name, byte val) throws IOException;
  
          /**
           * Get the value of the named char field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>char</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract char get(String name, char val) throws IOException;
  
          /**
           * Get the value of the named short field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>short</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract short get(String name, short val) throws IOException;
  
          /**
           * Get the value of the named int field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>int</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract int get(String name, int val) throws IOException;
  
          /**
           * Get the value of the named long field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>long</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract long get(String name, long val) throws IOException;
  
          /**
           * Get the value of the named float field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>float</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract float get(String name, float val) throws IOException;
  
          /**
           * Get the value of the named double field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>double</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract double get(String name, double val) throws IOException;
  
          /**
           * Get the value of the named Object field from the persistent field.
           *
           * @param  name the name of the field
           * @param  val the default value to use if <code>name</code> does not
           *         have a value
           * @return the value of the named <code>Object</code> field
           * @throws IOException if there are I/O errors while reading from the
           *         underlying <code>InputStream</code>
           * @throws IllegalArgumentException if type of <code>name</code> is
           *         not serializable or if the field type is incorrect
           */
          public abstract Object get(String name, Object val) throws IOException;
      }
  
      /**
       * Verifies that this (possibly subclass) instance can be constructed
       * without violating security constraints: the subclass must not override
       * security-sensitive non-final methods, or else the
       * "enableSubclassImplementation" SerializablePermission is checked.
       */
      private void verifySubclass() {
          Class<?> cl = getClass();
          if (cl == ObjectInputStream.class) {
              return;
          }
          SecurityManager sm = System.getSecurityManager();
          if (sm == null) {
              return;
          }
          processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
          WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
          Boolean result = Caches.subclassAudits.get(key);
          if (result == null) {
              result = Boolean.valueOf(auditSubclass(cl));
              Caches.subclassAudits.putIfAbsent(key, result);
          }
          if (result.booleanValue()) {
              return;
          }
          sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
      }
  
      /**
       * Performs reflective checks on given subclass to verify that it doesn't
       * override security-sensitive non-final methods.  Returns true if subclass
       * is "safe", false otherwise.
       */
      private static boolean auditSubclass(final Class<?> subcl) {
          Boolean result = AccessController.doPrivileged(
              new PrivilegedAction<Boolean>() {
                  public Boolean run() {
                      for (Class<?> cl = subcl;
                           cl != ObjectInputStream.class;
                           cl = cl.getSuperclass())
                      {
                          try {
                              cl.getDeclaredMethod(
                                  "readUnshared", (Class[]) null);
                              return Boolean.FALSE;
                          } catch (NoSuchMethodException ex) {
                          }
                          try {
                              cl.getDeclaredMethod("readFields", (Class[]) null);
                              return Boolean.FALSE;
                          } catch (NoSuchMethodException ex) {
                          }
                      }
                      return Boolean.TRUE;
                  }
              }
          );
          return result.booleanValue();
      }
  
      /**
       * Clears internal data structures.
       */
      private void clear() {
          handles.clear();
          vlist.clear();
      }
  
      /**
       * Underlying readObject implementation.
       */
      private Object readObject0(boolean unshared) throws IOException {
          boolean oldMode = bin.getBlockDataMode();
          if (oldMode) {
              int remain = bin.currentBlockRemaining();
              if (remain > 0) {
                  throw new OptionalDataException(remain);
              } else if (defaultDataEnd) {
                  /*
                   * Fix for 4360508: stream is currently at the end of a field
                   * value block written via default serialization; since there
                   * is no terminating TC_ENDBLOCKDATA tag, simulate
                   * end-of-custom-data behavior explicitly.
                   */
                  throw new OptionalDataException(true);
              }
              bin.setBlockDataMode(false);
          }
  
          byte tc;
          while ((tc = bin.peekByte()) == TC_RESET) {
              bin.readByte();
              handleReset();
          }
  
          depth++;
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // totalObjectRefs++;
          try {
              switch (tc) {
                  case TC_NULL:
                      return readNull();
  
                  case TC_REFERENCE:
                      return readHandle(unshared);
  
                  case TC_CLASS:
                      return readClass(unshared);
  
                  case TC_CLASSDESC:
                  case TC_PROXYCLASSDESC:
                      return readClassDesc(unshared);
  
                  case TC_STRING:
                  case TC_LONGSTRING:
                      return checkResolve(readString(unshared));
  
                  case TC_ARRAY:
                      return checkResolve(readArray(unshared));
  
                  case TC_ENUM:
                      return checkResolve(readEnum(unshared));
  
                  case TC_OBJECT:
                      return checkResolve(readOrdinaryObject(unshared));
  
                  case TC_EXCEPTION:
                      IOException ex = readFatalException();
                      throw new WriteAbortedException("writing aborted", ex);
  
                  case TC_BLOCKDATA:
                  case TC_BLOCKDATALONG:
                      if (oldMode) {
                          bin.setBlockDataMode(true);
                          bin.peek();             // force header read
                          throw new OptionalDataException(
                              bin.currentBlockRemaining());
                      } else {
                          throw new StreamCorruptedException(
                              "unexpected block data");
                      }
  
                  case TC_ENDBLOCKDATA:
                      if (oldMode) {
                          throw new OptionalDataException(true);
                      } else {
                          throw new StreamCorruptedException(
                              "unexpected end of block data");
                      }
  
                  default:
                      throw new StreamCorruptedException(
                          String.format("invalid type code: %02X", tc));
              }
          } finally {
              depth--;
              bin.setBlockDataMode(oldMode);
          }
      }
  
      /**
       * If resolveObject has been enabled and given object does not have an
       * exception associated with it, calls resolveObject to determine
       * replacement for object, and updates handle table accordingly.  Returns
       * replacement object, or echoes provided object if no replacement
       * occurred.  Expects that passHandle is set to given object's handle prior
       * to calling this method.
       */
      private Object checkResolve(Object obj) throws IOException {
          if (!enableResolve || handles.lookupException(passHandle) != null) {
              return obj;
          }
          Object rep = resolveObject(obj);
          if (rep != obj) {
              // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
              /*
              // The type of the original object has been filtered but resolveObject
              // may have replaced it;  filter the replacement's type
              if (rep != null) {
                  if (rep.getClass().isArray()) {
                      filterCheck(rep.getClass(), Array.getLength(rep));
                  } else {
                      filterCheck(rep.getClass(), -1);
                  }
              }
              */
              handles.setObject(passHandle, rep);
          }
          return rep;
      }
  
      /**
       * Reads string without allowing it to be replaced in stream.  Called from
       * within ObjectStreamClass.read().
       */
      String readTypeString() throws IOException {
          int oldHandle = passHandle;
          try {
              byte tc = bin.peekByte();
              switch (tc) {
                  case TC_NULL:
                      return (String) readNull();
  
                  case TC_REFERENCE:
                      return (String) readHandle(false);
  
                  case TC_STRING:
                  case TC_LONGSTRING:
                      return readString(false);
  
                  default:
                      throw new StreamCorruptedException(
                          String.format("invalid type code: %02X", tc));
              }
          } finally {
              passHandle = oldHandle;
          }
      }
  
      /**
       * Reads in null code, sets passHandle to NULL_HANDLE and returns null.
       */
      private Object readNull() throws IOException {
          if (bin.readByte() != TC_NULL) {
              throw new InternalError();
          }
          passHandle = NULL_HANDLE;
          return null;
      }
  
      /**
       * Reads in object handle, sets passHandle to the read handle, and returns
       * object associated with the handle.
       */
      private Object readHandle(boolean unshared) throws IOException {
          if (bin.readByte() != TC_REFERENCE) {
              throw new InternalError();
          }
          passHandle = bin.readInt() - baseWireHandle;
          if (passHandle < 0 || passHandle >= handles.size()) {
              throw new StreamCorruptedException(
                  String.format("invalid handle value: %08X", passHandle +
                  baseWireHandle));
          }
          if (unshared) {
              // REMIND: what type of exception to throw here?
              throw new InvalidObjectException(
                  "cannot read back reference as unshared");
          }
  
          Object obj = handles.lookupObject(passHandle);
          if (obj == unsharedMarker) {
              // REMIND: what type of exception to throw here?
              throw new InvalidObjectException(
                  "cannot read back reference to unshared object");
          }
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // filterCheck(null, -1);       // just a check for number of references, depth, no class
          return obj;
      }
  
      /**
       * Reads in and returns class object.  Sets passHandle to class object's
       * assigned handle.  Returns null if class is unresolvable (in which case a
       * ClassNotFoundException will be associated with the class' handle in the
       * handle table).
       */
      private Class<?> readClass(boolean unshared) throws IOException {
          if (bin.readByte() != TC_CLASS) {
              throw new InternalError();
          }
          ObjectStreamClass desc = readClassDesc(false);
          Class<?> cl = desc.forClass();
          passHandle = handles.assign(unshared ? unsharedMarker : cl);
  
          ClassNotFoundException resolveEx = desc.getResolveException();
          if (resolveEx != null) {
              handles.markException(passHandle, resolveEx);
          }
  
          handles.finish(passHandle);
          return cl;
      }
  
      /**
       * Reads in and returns (possibly null) class descriptor.  Sets passHandle
       * to class descriptor's assigned handle.  If class descriptor cannot be
       * resolved to a class in the local VM, a ClassNotFoundException is
       * associated with the class descriptor's handle.
       */
      private ObjectStreamClass readClassDesc(boolean unshared)
          throws IOException
      {
          byte tc = bin.peekByte();
          ObjectStreamClass descriptor;
          switch (tc) {
              case TC_NULL:
                  descriptor = (ObjectStreamClass) readNull();
                  break;
              case TC_REFERENCE:
                  descriptor = (ObjectStreamClass) readHandle(unshared);
                  break;
              case TC_PROXYCLASSDESC:
                  descriptor = readProxyDesc(unshared);
                  break;
              case TC_CLASSDESC:
                  descriptor = readNonProxyDesc(unshared);
                  break;
              default:
                  throw new StreamCorruptedException(
                      String.format("invalid type code: %02X", tc));
          }
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // if (descriptor != null) {
          //     validateDescriptor(descriptor);
          // }
          return descriptor;
      }
  
      private boolean isCustomSubclass() {
          // Return true if this class is a custom subclass of ObjectInputStream
          return getClass().getClassLoader()
                      != ObjectInputStream.class.getClassLoader();
      }
  
      /**
       * Reads in and returns class descriptor for a dynamic proxy class.  Sets
       * passHandle to proxy class descriptor's assigned handle.  If proxy class
       * descriptor cannot be resolved to a class in the local VM, a
       * ClassNotFoundException is associated with the descriptor's handle.
       */
      private ObjectStreamClass readProxyDesc(boolean unshared)
          throws IOException
      {
          if (bin.readByte() != TC_PROXYCLASSDESC) {
              throw new InternalError();
          }
  
          ObjectStreamClass desc = new ObjectStreamClass();
          int descHandle = handles.assign(unshared ? unsharedMarker : desc);
          passHandle = NULL_HANDLE;
  
          int numIfaces = bin.readInt();
          String[] ifaces = new String[numIfaces];
          for (int i = 0; i < numIfaces; i++) {
              ifaces[i] = bin.readUTF();
          }
  
          Class<?> cl = null;
          ClassNotFoundException resolveEx = null;
          bin.setBlockDataMode(true);
          try {
              if ((cl = resolveProxyClass(ifaces)) == null) {
                  resolveEx = new ClassNotFoundException("null class");
              } else if (!Proxy.isProxyClass(cl)) {
                  throw new InvalidClassException("Not a proxy");
              } else {
                  // ReflectUtil.checkProxyPackageAccess makes a test
                  // equivalent to isCustomSubclass so there's no need
                  // to condition this call to isCustomSubclass == true here.
                  ReflectUtil.checkProxyPackageAccess(
                          getClass().getClassLoader(),
                          cl.getInterfaces());
                  // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
                  // // Filter the interfaces
                  // for (Class<?> clazz : cl.getInterfaces()) {
                  //     filterCheck(clazz, -1);
                  // }
              }
          } catch (ClassNotFoundException ex) {
              resolveEx = ex;
          }
          skipCustomData();
  
          desc.initProxy(cl, resolveEx, readClassDesc(false));
  
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // // Call filterCheck on the definition
          // filterCheck(desc.forClass(), -1);
  
          handles.finish(descHandle);
          passHandle = descHandle;
          return desc;
      }
  
      /**
       * Reads in and returns class descriptor for a class that is not a dynamic
       * proxy class.  Sets passHandle to class descriptor's assigned handle.  If
       * class descriptor cannot be resolved to a class in the local VM, a
       * ClassNotFoundException is associated with the descriptor's handle.
       */
      private ObjectStreamClass readNonProxyDesc(boolean unshared)
          throws IOException
      {
          if (bin.readByte() != TC_CLASSDESC) {
              throw new InternalError();
          }
  
          ObjectStreamClass desc = new ObjectStreamClass();
          int descHandle = handles.assign(unshared ? unsharedMarker : desc);
          passHandle = NULL_HANDLE;
  
          ObjectStreamClass readDesc = null;
          try {
              readDesc = readClassDescriptor();
          } catch (ClassNotFoundException ex) {
              throw (IOException) new InvalidClassException(
                  "failed to read class descriptor").initCause(ex);
          }
  
          Class<?> cl = null;
          ClassNotFoundException resolveEx = null;
          bin.setBlockDataMode(true);
          final boolean checksRequired = isCustomSubclass();
          try {
              if ((cl = resolveClass(readDesc)) == null) {
                  resolveEx = new ClassNotFoundException("null class");
              } else if (checksRequired) {
                  ReflectUtil.checkPackageAccess(cl);
              }
          } catch (ClassNotFoundException ex) {
              resolveEx = ex;
          }
          skipCustomData();
  
          desc.initNonProxy(readDesc, cl, resolveEx, readClassDesc(false));
  
          // Android-removed: ObjectInputFilter unsupported - removed filterCheck() call.
          // // Call filterCheck on the definition
          // filterCheck(desc.forClass(), -1);
  
          handles.finish(descHandle);
          passHandle = descHandle;
  
          return desc;
      }
  
      /**
       * Reads in and returns new string.  Sets passHandle to new string's
       * assigned handle.
       */
      private String readString(boolean unshared) throws IOException {
          String str;
          byte tc = bin.readByte();
          switch (tc) {
              case TC_STRING:
                  str = bin.readUTF();
                  break;
  
              case TC_LONGSTRING:
                  str = bin.readLongUTF();
                  break;
  
              default:
                  throw new StreamCorruptedException(
                      String.format("invalid type code: %02X", tc));
          }
          passHandle = handles.assign(unshared ? unsharedMarker : str);
          handles.finish(passHandle);
          return str;
      }
  
      /**
       * Reads in and returns array object, or null if array class is
       * unresolvable.  Sets passHandle to array's assigned handle.
       */
      private Object readArray(boolean unshared) throws IOException {
          if (bin.readByte() != TC_ARRAY) {
              throw new InternalError();
          }
  
          ObjectStreamClass desc = readClassDesc(false);
          int len = bin.readInt();
  
          // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
          // filterCheck(desc.forClass(), len);
  
          Object array = null;
          Class<?> cl, ccl = null;
          if ((cl = desc.forClass()) != null) {
              ccl = cl.getComponentType();
              array = Array.newInstance(ccl, len);
          }
  
          int arrayHandle = handles.assign(unshared ? unsharedMarker : array);
          ClassNotFoundException resolveEx = desc.getResolveException();
          if (resolveEx != null) {
              handles.markException(arrayHandle, resolveEx);
          }
  
          if (ccl == null) {
              for (int i = 0; i < len; i++) {
                  readObject0(false);
              }
          } else if (ccl.isPrimitive()) {
              if (ccl == Integer.TYPE) {
                  bin.readInts((int[]) array, 0, len);
              } else if (ccl == Byte.TYPE) {
                  bin.readFully((byte[]) array, 0, len, true);
              } else if (ccl == Long.TYPE) {
                  bin.readLongs((long[]) array, 0, len);
              } else if (ccl == Float.TYPE) {
                  bin.readFloats((float[]) array, 0, len);
              } else if (ccl == Double.TYPE) {
                  bin.readDoubles((double[]) array, 0, len);
              } else if (ccl == Short.TYPE) {
                  bin.readShorts((short[]) array, 0, len);
              } else if (ccl == Character.TYPE) {
                  bin.readChars((char[]) array, 0, len);
              } else if (ccl == Boolean.TYPE) {
                  bin.readBooleans((boolean[]) array, 0, len);
              } else {
                  throw new InternalError();
              }
          } else {
              Object[] oa = (Object[]) array;
              for (int i = 0; i < len; i++) {
                  oa[i] = readObject0(false);
                  handles.markDependency(arrayHandle, passHandle);
              }
          }
  
          handles.finish(arrayHandle);
          passHandle = arrayHandle;
          return array;
      }
  
      /**
       * Reads in and returns enum constant, or null if enum type is
       * unresolvable.  Sets passHandle to enum constant's assigned handle.
       */
      private Enum<?> readEnum(boolean unshared) throws IOException {
          if (bin.readByte() != TC_ENUM) {
              throw new InternalError();
          }
  
          ObjectStreamClass desc = readClassDesc(false);
          if (!desc.isEnum()) {
              throw new InvalidClassException("non-enum class: " + desc);
          }
  
          int enumHandle = handles.assign(unshared ? unsharedMarker : null);
          ClassNotFoundException resolveEx = desc.getResolveException();
          if (resolveEx != null) {
              handles.markException(enumHandle, resolveEx);
          }
  
          String name = readString(false);
          Enum<?> result = null;
          Class<?> cl = desc.forClass();
          if (cl != null) {
              try {
                  @SuppressWarnings("unchecked")
                  Enum<?> en = Enum.valueOf((Class)cl, name);
                  result = en;
              } catch (IllegalArgumentException ex) {
                  throw (IOException) new InvalidObjectException(
                      "enum constant " + name + " does not exist in " +
                      cl).initCause(ex);
              }
              if (!unshared) {
                  handles.setObject(enumHandle, result);
              }
          }
  
          handles.finish(enumHandle);
          passHandle = enumHandle;
          return result;
      }
  
      /**
       * Reads and returns "ordinary" (i.e., not a String, Class,
       * ObjectStreamClass, array, or enum constant) object, or null if object's
       * class is unresolvable (in which case a ClassNotFoundException will be
       * associated with object's handle).  Sets passHandle to object's assigned
       * handle.
       */
      private Object readOrdinaryObject(boolean unshared)
          throws IOException
      {
          if (bin.readByte() != TC_OBJECT) {
              throw new InternalError();
          }
  
          ObjectStreamClass desc = readClassDesc(false);
          desc.checkDeserialize();
  
          Class<?> cl = desc.forClass();
          if (cl == String.class || cl == Class.class
                  || cl == ObjectStreamClass.class) {
              throw new InvalidClassException("invalid class descriptor");
          }
  
          Object obj;
          try {
              obj = desc.isInstantiable() ? desc.newInstance() : null;
          } catch (Exception ex) {
              throw (IOException) new InvalidClassException(
                  desc.forClass().getName(),
                  "unable to create instance").initCause(ex);
          }
  
          passHandle = handles.assign(unshared ? unsharedMarker : obj);
          ClassNotFoundException resolveEx = desc.getResolveException();
          if (resolveEx != null) {
              handles.markException(passHandle, resolveEx);
          }
  
          if (desc.isExternalizable()) {
              readExternalData((Externalizable) obj, desc);
          } else {
              readSerialData(obj, desc);
          }
  
          handles.finish(passHandle);
  
          if (obj != null &&
              handles.lookupException(passHandle) == null &&
              desc.hasReadResolveMethod())
          {
              Object rep = desc.invokeReadResolve(obj);
              if (unshared && rep.getClass().isArray()) {
                  rep = cloneArray(rep);
              }
              if (rep != obj) {
                  // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
                  /*
                  // Filter the replacement object
                  if (rep != null) {
                      if (rep.getClass().isArray()) {
                          filterCheck(rep.getClass(), Array.getLength(rep));
                      } else {
                          filterCheck(rep.getClass(), -1);
                      }
                  }
                  */
                  handles.setObject(passHandle, obj = rep);
              }
          }
  
          return obj;
      }
  
      /**
       * If obj is non-null, reads externalizable data by invoking readExternal()
       * method of obj; otherwise, attempts to skip over externalizable data.
       * Expects that passHandle is set to obj's handle before this method is
       * called.
       */
      private void readExternalData(Externalizable obj, ObjectStreamClass desc)
          throws IOException
      {
          SerialCallbackContext oldContext = curContext;
          if (oldContext != null)
              oldContext.check();
          curContext = null;
          try {
              boolean blocked = desc.hasBlockExternalData();
              if (blocked) {
                  bin.setBlockDataMode(true);
              }
              if (obj != null) {
                  try {
                      obj.readExternal(this);
                  } catch (ClassNotFoundException ex) {
                      /*
                       * In most cases, the handle table has already propagated
                       * a CNFException to passHandle at this point; this mark
                       * call is included to address cases where the readExternal
                       * method has cons'ed and thrown a new CNFException of its
                       * own.
                       */
                       handles.markException(passHandle, ex);
                  }
              }
              if (blocked) {
                  skipCustomData();
              }
          } finally {
              if (oldContext != null)
                  oldContext.check();
              curContext = oldContext;
          }
          /*
           * At this point, if the externalizable data was not written in
           * block-data form and either the externalizable class doesn't exist
           * locally (i.e., obj == null) or readExternal() just threw a
           * CNFException, then the stream is probably in an inconsistent state,
           * since some (or all) of the externalizable data may not have been
           * consumed.  Since there's no "correct" action to take in this case,
           * we mimic the behavior of past serialization implementations and
           * blindly hope that the stream is in sync; if it isn't and additional
           * externalizable data remains in the stream, a subsequent read will
           * most likely throw a StreamCorruptedException.
           */
      }
  
      /**
       * Reads (or attempts to skip, if obj is null or is tagged with a
       * ClassNotFoundException) instance data for each serializable class of
       * object in stream, from superclass to subclass.  Expects that passHandle
       * is set to obj's handle before this method is called.
       */
      private void readSerialData(Object obj, ObjectStreamClass desc)
          throws IOException
      {
          ObjectStreamClass.ClassDataSlot[] slots = desc.getClassDataLayout();
          for (int i = 0; i < slots.length; i++) {
              ObjectStreamClass slotDesc = slots[i].desc;
  
              if (slots[i].hasData) {
                  if (obj == null || handles.lookupException(passHandle) != null) {
                      defaultReadFields(null, slotDesc); // skip field values
                  } else if (slotDesc.hasReadObjectMethod()) {
                      // BEGIN Android-changed: ThreadDeath cannot cause corruption on Android.
                      // Android does not support Thread.stop() or Thread.stop(Throwable) so this
                      // does not need to protect against state corruption that can occur when a
                      // ThreadDeath Error is thrown in the middle of the finally block.
                      SerialCallbackContext oldContext = curContext;
                      if (oldContext != null)
                          oldContext.check();
                      try {
                          curContext = new SerialCallbackContext(obj, slotDesc);
  
                          bin.setBlockDataMode(true);
                          slotDesc.invokeReadObject(obj, this);
                      } catch (ClassNotFoundException ex) {
                          /*
                           * In most cases, the handle table has already
                           * propagated a CNFException to passHandle at this
                           * point; this mark call is included to address cases
                           * where the custom readObject method has cons'ed and
                           * thrown a new CNFException of its own.
                           */
                          handles.markException(passHandle, ex);
                      } finally {
                          curContext.setUsed();
                          if (oldContext!= null)
                              oldContext.check();
                          curContext = oldContext;
                          // END Android-changed: ThreadDeath cannot cause corruption on Android.
                      }
  
                      /*
                       * defaultDataEnd may have been set indirectly by custom
                       * readObject() method when calling defaultReadObject() or
                       * readFields(); clear it to restore normal read behavior.
                       */
                      defaultDataEnd = false;
                  } else {
                      defaultReadFields(obj, slotDesc);
                      }
  
                  if (slotDesc.hasWriteObjectData()) {
                      skipCustomData();
                  } else {
                      bin.setBlockDataMode(false);
                  }
              } else {
                  if (obj != null &&
                      slotDesc.hasReadObjectNoDataMethod() &&
                      handles.lookupException(passHandle) == null)
                  {
                      slotDesc.invokeReadObjectNoData(obj);
                  }
              }
          }
              }
  
      /**
       * Skips over all block data and objects until TC_ENDBLOCKDATA is
       * encountered.
       */
      private void skipCustomData() throws IOException {
          int oldHandle = passHandle;
          for (;;) {
              if (bin.getBlockDataMode()) {
                  bin.skipBlockData();
                  bin.setBlockDataMode(false);
              }
              switch (bin.peekByte()) {
                  case TC_BLOCKDATA:
                  case TC_BLOCKDATALONG:
                      bin.setBlockDataMode(true);
                      break;
  
                  case TC_ENDBLOCKDATA:
                      bin.readByte();
                      passHandle = oldHandle;
                      return;
  
                  default:
                      readObject0(false);
                      break;
              }
          }
      }
  
      /**
       * Reads in values of serializable fields declared by given class
       * descriptor.  If obj is non-null, sets field values in obj.  Expects that
       * passHandle is set to obj's handle before this method is called.
       */
      private void defaultReadFields(Object obj, ObjectStreamClass desc)
          throws IOException
      {
          Class<?> cl = desc.forClass();
          if (cl != null && obj != null && !cl.isInstance(obj)) {
              throw new ClassCastException();
          }
  
          int primDataSize = desc.getPrimDataSize();
          if (primVals == null || primVals.length < primDataSize) {
              primVals = new byte[primDataSize];
          }
              bin.readFully(primVals, 0, primDataSize, false);
          if (obj != null) {
              desc.setPrimFieldValues(obj, primVals);
          }
  
          int objHandle = passHandle;
          ObjectStreamField[] fields = desc.getFields(false);
          Object[] objVals = new Object[desc.getNumObjFields()];
          int numPrimFields = fields.length - objVals.length;
          for (int i = 0; i < objVals.length; i++) {
              ObjectStreamField f = fields[numPrimFields + i];
              objVals[i] = readObject0(f.isUnshared());
              if (f.getField() != null) {
                  handles.markDependency(objHandle, passHandle);
              }
          }
          if (obj != null) {
              desc.setObjFieldValues(obj, objVals);
          }
          passHandle = objHandle;
      }
  
      /**
       * Reads in and returns IOException that caused serialization to abort.
       * All stream state is discarded prior to reading in fatal exception.  Sets
       * passHandle to fatal exception's handle.
       */
      private IOException readFatalException() throws IOException {
          if (bin.readByte() != TC_EXCEPTION) {
              throw new InternalError();
          }
          clear();
          // BEGIN Android-changed: Fix SerializationStressTest#test_2_writeReplace.
          IOException e = (IOException) readObject0(false);
          // If we want to continue reading from same stream after fatal exception, we
          // need to clear internal data structures.
          clear();
          return e;
          // END Android-changed: Fix SerializationStressTest#test_2_writeReplace.
      }
  
      /**
       * If recursion depth is 0, clears internal data structures; otherwise,
       * throws a StreamCorruptedException.  This method is called when a
       * TC_RESET typecode is encountered.
       */
      private void handleReset() throws StreamCorruptedException {
          if (depth > 0) {
              throw new StreamCorruptedException(
                  "unexpected reset; recursion depth: " + depth);
          }
          clear();
      }
  
      /**
       * Converts specified span of bytes into float values.
       */
      // REMIND: remove once hotspot inlines Float.intBitsToFloat
      private static native void bytesToFloats(byte[] src, int srcpos,
                                               float[] dst, int dstpos,
                                               int nfloats);
  
      /**
       * Converts specified span of bytes into double values.
       */
      // REMIND: remove once hotspot inlines Double.longBitsToDouble
      private static native void bytesToDoubles(byte[] src, int srcpos,
                                                double[] dst, int dstpos,
                                                int ndoubles);
  
      /**
       * Returns the first non-null class loader (not counting class loaders of
       * generated reflection implementation classes) up the execution stack, or
       * null if only code from the null class loader is on the stack.  This
       * method is also called via reflection by the following RMI-IIOP class:
       *
       *     com.sun.corba.se.internal.util.JDKClassLoader
       *
       * This method should not be removed or its signature changed without
       * corresponding modifications to the above class.
       */
      private static ClassLoader latestUserDefinedLoader() {
          // Android-changed: Use VMStack on Android.
          return VMStack.getClosestUserClassLoader();
      }
  
      /**
       * Default GetField implementation.
       */
      private class GetFieldImpl extends GetField {
  
          /** class descriptor describing serializable fields */
          private final ObjectStreamClass desc;
          /** primitive field values */
          private final byte[] primVals;
          /** object field values */
          private final Object[] objVals;
          /** object field value handles */
          private final int[] objHandles;
  
          /**
           * Creates GetFieldImpl object for reading fields defined in given
           * class descriptor.
           */
          GetFieldImpl(ObjectStreamClass desc) {
              this.desc = desc;
              primVals = new byte[desc.getPrimDataSize()];
              objVals = new Object[desc.getNumObjFields()];
              objHandles = new int[objVals.length];
          }
  
          public ObjectStreamClass getObjectStreamClass() {
              return desc;
          }
  
          public boolean defaulted(String name) throws IOException {
              return (getFieldOffset(name, null) < 0);
          }
  
          public boolean get(String name, boolean val) throws IOException {
              int off = getFieldOffset(name, Boolean.TYPE);
              return (off >= 0) ? Bits.getBoolean(primVals, off) : val;
          }
  
          public byte get(String name, byte val) throws IOException {
              int off = getFieldOffset(name, Byte.TYPE);
              return (off >= 0) ? primVals[off] : val;
          }
  
          public char get(String name, char val) throws IOException {
              int off = getFieldOffset(name, Character.TYPE);
              return (off >= 0) ? Bits.getChar(primVals, off) : val;
          }
  
          public short get(String name, short val) throws IOException {
              int off = getFieldOffset(name, Short.TYPE);
              return (off >= 0) ? Bits.getShort(primVals, off) : val;
          }
  
          public int get(String name, int val) throws IOException {
              int off = getFieldOffset(name, Integer.TYPE);
              return (off >= 0) ? Bits.getInt(primVals, off) : val;
          }
  
          public float get(String name, float val) throws IOException {
              int off = getFieldOffset(name, Float.TYPE);
              return (off >= 0) ? Bits.getFloat(primVals, off) : val;
          }
  
          public long get(String name, long val) throws IOException {
              int off = getFieldOffset(name, Long.TYPE);
              return (off >= 0) ? Bits.getLong(primVals, off) : val;
          }
  
          public double get(String name, double val) throws IOException {
              int off = getFieldOffset(name, Double.TYPE);
              return (off >= 0) ? Bits.getDouble(primVals, off) : val;
          }
  
          public Object get(String name, Object val) throws IOException {
              int off = getFieldOffset(name, Object.class);
              if (off >= 0) {
                  int objHandle = objHandles[off];
                  handles.markDependency(passHandle, objHandle);
                  return (handles.lookupException(objHandle) == null) ?
                      objVals[off] : null;
              } else {
                  return val;
              }
          }
  
          /**
           * Reads primitive and object field values from stream.
           */
          void readFields() throws IOException {
              bin.readFully(primVals, 0, primVals.length, false);
  
              int oldHandle = passHandle;
              ObjectStreamField[] fields = desc.getFields(false);
              int numPrimFields = fields.length - objVals.length;
              for (int i = 0; i < objVals.length; i++) {
                  objVals[i] =
                      readObject0(fields[numPrimFields + i].isUnshared());
                  objHandles[i] = passHandle;
              }
              passHandle = oldHandle;
          }
  
          /**
           * Returns offset of field with given name and type.  A specified type
           * of null matches all types, Object.class matches all non-primitive
           * types, and any other non-null type matches assignable types only.
           * If no matching field is found in the (incoming) class
           * descriptor but a matching field is present in the associated local
           * class descriptor, returns -1.  Throws IllegalArgumentException if
           * neither incoming nor local class descriptor contains a match.
           */
          private int getFieldOffset(String name, Class<?> type) {
              ObjectStreamField field = desc.getField(name, type);
              if (field != null) {
                  return field.getOffset();
              } else if (desc.getLocalDesc().getField(name, type) != null) {
                  return -1;
              } else {
                  throw new IllegalArgumentException("no such field " + name +
                                                     " with type " + type);
              }
          }
      }
  
      /**
       * Prioritized list of callbacks to be performed once object graph has been
       * completely deserialized.
       */
      private static class ValidationList {
  
          private static class Callback {
              final ObjectInputValidation obj;
              final int priority;
              Callback next;
              final AccessControlContext acc;
  
              Callback(ObjectInputValidation obj, int priority, Callback next,
                  AccessControlContext acc)
              {
                  this.obj = obj;
                  this.priority = priority;
                  this.next = next;
                  this.acc = acc;
              }
          }
  
          /** linked list of callbacks */
          private Callback list;
  
          /**
           * Creates new (empty) ValidationList.
           */
          ValidationList() {
          }
  
          /**
           * Registers callback.  Throws InvalidObjectException if callback
           * object is null.
           */
          void register(ObjectInputValidation obj, int priority)
              throws InvalidObjectException
          {
              if (obj == null) {
                  throw new InvalidObjectException("null callback");
              }
  
              Callback prev = null, cur = list;
              while (cur != null && priority < cur.priority) {
                  prev = cur;
                  cur = cur.next;
              }
              AccessControlContext acc = AccessController.getContext();
              if (prev != null) {
                  prev.next = new Callback(obj, priority, cur, acc);
              } else {
                  list = new Callback(obj, priority, list, acc);
              }
          }
  
          /**
           * Invokes all registered callbacks and clears the callback list.
           * Callbacks with higher priorities are called first; those with equal
           * priorities may be called in any order.  If any of the callbacks
           * throws an InvalidObjectException, the callback process is terminated
           * and the exception propagated upwards.
           */
          void doCallbacks() throws InvalidObjectException {
              try {
                  while (list != null) {
                      AccessController.doPrivileged(
                          new PrivilegedExceptionAction<Void>()
                      {
                          public Void run() throws InvalidObjectException {
                              list.obj.validateObject();
                              return null;
                          }
                      }, list.acc);
                      list = list.next;
                  }
              } catch (PrivilegedActionException ex) {
                  list = null;
                  throw (InvalidObjectException) ex.getException();
              }
          }
  
          /**
           * Resets the callback list to its initial (empty) state.
           */
          public void clear() {
              list = null;
          }
      }
  
      // Android-removed: ObjectInputFilter logic, to be reconsidered. http://b/110252929
      // Removed FilterValues class.
  
      /**
       * Input stream supporting single-byte peek operations.
       */
      private static class PeekInputStream extends InputStream {
  
          /** underlying stream */
          private final InputStream in;
          /** peeked byte */
          private int peekb = -1;
          /** total bytes read from the stream */
          private long totalBytesRead = 0;
  
          /**
           * Creates new PeekInputStream on top of given underlying stream.
           */
          PeekInputStream(InputStream in) {
              this.in = in;
          }
  
          /**
           * Peeks at next byte value in stream.  Similar to read(), except
           * that it does not consume the read value.
           */
          int peek() throws IOException {
              if (peekb >= 0) {
                  return peekb;
              }
              peekb = in.read();
              totalBytesRead += peekb >= 0 ? 1 : 0;
              return peekb;
          }
  
          public int read() throws IOException {
              if (peekb >= 0) {
                  int v = peekb;
                  peekb = -1;
                  return v;
              } else {
                  int nbytes = in.read();
                  totalBytesRead += nbytes >= 0 ? 1 : 0;
                  return nbytes;
              }
          }
  
          public int read(byte[] b, int off, int len) throws IOException {
              int nbytes;
              if (len == 0) {
                  return 0;
              } else if (peekb < 0) {
                  nbytes = in.read(b, off, len);
                  totalBytesRead += nbytes >= 0 ? nbytes : 0;
                  return nbytes;
              } else {
                  b[off++] = (byte) peekb;
                  len--;
                  peekb = -1;
                  nbytes = in.read(b, off, len);
                  totalBytesRead += nbytes >= 0 ? nbytes : 0;
                  return (nbytes >= 0) ? (nbytes + 1) : 1;
              }
          }
  
          void readFully(byte[] b, int off, int len) throws IOException {
              int n = 0;
              while (n < len) {
                  int count = read(b, off + n, len - n);
                  if (count < 0) {
                      throw new EOFException();
                  }
                  n += count;
              }
          }
  
          public long skip(long n) throws IOException {
              if (n <= 0) {
                  return 0;
              }
              int skipped = 0;
              if (peekb >= 0) {
                  peekb = -1;
                  skipped++;
                  n--;
              }
              n = skipped + in.skip(n);
              totalBytesRead += n;
              return n;
          }
  
          public int available() throws IOException {
              return in.available() + ((peekb >= 0) ? 1 : 0);
          }
  
          public void close() throws IOException {
              in.close();
          }
  
          public long getBytesRead() {
              return totalBytesRead;
          }
      }
  
      /**
       * Input stream with two modes: in default mode, inputs data written in the
       * same format as DataOutputStream; in "block data" mode, inputs data
       * bracketed by block data markers (see object serialization specification
       * for details).  Buffering depends on block data mode: when in default
       * mode, no data is buffered in advance; when in block data mode, all data
       * for the current data block is read in at once (and buffered).
       */
      private class BlockDataInputStream
          extends InputStream implements DataInput
      {
          /** maximum data block length */
          private static final int MAX_BLOCK_SIZE = 1024;
          /** maximum data block header length */
          private static final int MAX_HEADER_SIZE = 5;
          /** (tunable) length of char buffer (for reading strings) */
          private static final int CHAR_BUF_SIZE = 256;
          /** readBlockHeader() return value indicating header read may block */
          private static final int HEADER_BLOCKED = -2;
  
          /** buffer for reading general/block data */
          private final byte[] buf = new byte[MAX_BLOCK_SIZE];
          /** buffer for reading block data headers */
          private final byte[] hbuf = new byte[MAX_HEADER_SIZE];
          /** char buffer for fast string reads */
          private final char[] cbuf = new char[CHAR_BUF_SIZE];
  
          /** block data mode */
          private boolean blkmode = false;
  
          // block data state fields; values meaningful only when blkmode true
          /** current offset into buf */
          private int pos = 0;
          /** end offset of valid data in buf, or -1 if no more block data */
          private int end = -1;
          /** number of bytes in current block yet to be read from stream */
          private int unread = 0;
  
          /** underlying stream (wrapped in peekable filter stream) */
          private final PeekInputStream in;
          /** loopback stream (for data reads that span data blocks) */
          private final DataInputStream din;
  
          /**
           * Creates new BlockDataInputStream on top of given underlying stream.
           * Block data mode is turned off by default.
           */
          BlockDataInputStream(InputStream in) {
              this.in = new PeekInputStream(in);
              din = new DataInputStream(this);
          }
  
          /**
           * Sets block data mode to the given mode (true == on, false == off)
           * and returns the previous mode value.  If the new mode is the same as
           * the old mode, no action is taken.  Throws IllegalStateException if
           * block data mode is being switched from on to off while unconsumed
           * block data is still present in the stream.
           */
          boolean setBlockDataMode(boolean newmode) throws IOException {
              if (blkmode == newmode) {
                  return blkmode;
              }
              if (newmode) {
                  pos = 0;
                  end = 0;
                  unread = 0;
              } else if (pos < end) {
                  throw new IllegalStateException("unread block data");
              }
              blkmode = newmode;
              return !blkmode;
          }
  
          /**
           * Returns true if the stream is currently in block data mode, false
           * otherwise.
           */
          boolean getBlockDataMode() {
              return blkmode;
          }
  
          /**
           * If in block data mode, skips to the end of the current group of data
           * blocks (but does not unset block data mode).  If not in block data
           * mode, throws an IllegalStateException.
           */
          void skipBlockData() throws IOException {
              if (!blkmode) {
                  throw new IllegalStateException("not in block data mode");
              }
              while (end >= 0) {
                  refill();
              }
          }
  
          /**
           * Attempts to read in the next block data header (if any).  If
           * canBlock is false and a full header cannot be read without possibly
           * blocking, returns HEADER_BLOCKED, else if the next element in the
           * stream is a block data header, returns the block data length
           * specified by the header, else returns -1.
           */
          private int readBlockHeader(boolean canBlock) throws IOException {
              if (defaultDataEnd) {
                  /*
                   * Fix for 4360508: stream is currently at the end of a field
                   * value block written via default serialization; since there
                   * is no terminating TC_ENDBLOCKDATA tag, simulate
                   * end-of-custom-data behavior explicitly.
                   */
                  return -1;
              }
              try {
                  for (;;) {
                      int avail = canBlock ? Integer.MAX_VALUE : in.available();
                      if (avail == 0) {
                          return HEADER_BLOCKED;
                      }
  
                      int tc = in.peek();
                      switch (tc) {
                          case TC_BLOCKDATA:
                              if (avail < 2) {
                                  return HEADER_BLOCKED;
                              }
                              in.readFully(hbuf, 0, 2);
                              return hbuf[1] & 0xFF;
  
                          case TC_BLOCKDATALONG:
                              if (avail < 5) {
                                  return HEADER_BLOCKED;
                              }
                              in.readFully(hbuf, 0, 5);
                              int len = Bits.getInt(hbuf, 1);
                              if (len < 0) {
                                  throw new StreamCorruptedException(
                                      "illegal block data header length: " +
                                      len);
                              }
                              return len;
  
                          /*
                           * TC_RESETs may occur in between data blocks.
                           * Unfortunately, this case must be parsed at a lower
                           * level than other typecodes, since primitive data
                           * reads may span data blocks separated by a TC_RESET.
                           */
                          case TC_RESET:
                              in.read();
                              handleReset();
                              break;
  
                          default:
                              if (tc >= 0 && (tc < TC_BASE || tc > TC_MAX)) {
                                  throw new StreamCorruptedException(
                                      String.format("invalid type code: %02X",
                                      tc));
                              }
                              return -1;
                      }
                  }
              } catch (EOFException ex) {
                  throw new StreamCorruptedException(
                      "unexpected EOF while reading block data header");
              }
          }
  
          /**
           * Refills internal buffer buf with block data.  Any data in buf at the
           * time of the call is considered consumed.  Sets the pos, end, and
           * unread fields to reflect the new amount of available block data; if
           * the next element in the stream is not a data block, sets pos and
           * unread to 0 and end to -1.
           */
          private void refill() throws IOException {
              try {
                  do {
                      pos = 0;
                      if (unread > 0) {
                          int n =
                              in.read(buf, 0, Math.min(unread, MAX_BLOCK_SIZE));
                          if (n >= 0) {
                              end = n;
                              unread -= n;
                          } else {
                              throw new StreamCorruptedException(
                                  "unexpected EOF in middle of data block");
                          }
                      } else {
                          int n = readBlockHeader(true);
                          if (n >= 0) {
                              end = 0;
                              unread = n;
                          } else {
                              end = -1;
                              unread = 0;
                          }
                      }
                  } while (pos == end);
              } catch (IOException ex) {
                  pos = 0;
                  end = -1;
                  unread = 0;
                  throw ex;
              }
          }
  
          /**
           * If in block data mode, returns the number of unconsumed bytes
           * remaining in the current data block.  If not in block data mode,
           * throws an IllegalStateException.
           */
          int currentBlockRemaining() {
              if (blkmode) {
                  return (end >= 0) ? (end - pos) + unread : 0;
              } else {
                  throw new IllegalStateException();
              }
          }
  
          /**
           * Peeks at (but does not consume) and returns the next byte value in
           * the stream, or -1 if the end of the stream/block data (if in block
           * data mode) has been reached.
           */
          int peek() throws IOException {
              if (blkmode) {
                  if (pos == end) {
                      refill();
                  }
                  return (end >= 0) ? (buf[pos] & 0xFF) : -1;
              } else {
                  return in.peek();
              }
          }
  
          /**
           * Peeks at (but does not consume) and returns the next byte value in
           * the stream, or throws EOFException if end of stream/block data has
           * been reached.
           */
          byte peekByte() throws IOException {
              int val = peek();
              if (val < 0) {
                  throw new EOFException();
              }
              return (byte) val;
          }
  
  
          /* ----------------- generic input stream methods ------------------ */
          /*
           * The following methods are equivalent to their counterparts in
           * InputStream, except that they interpret data block boundaries and
           * read the requested data from within data blocks when in block data
           * mode.
           */
  
          public int read() throws IOException {
              if (blkmode) {
                  if (pos == end) {
                      refill();
                  }
                  return (end >= 0) ? (buf[pos++] & 0xFF) : -1;
              } else {
                  return in.read();
              }
          }
  
          public int read(byte[] b, int off, int len) throws IOException {
              return read(b, off, len, false);
          }
  
          public long skip(long len) throws IOException {
              long remain = len;
              while (remain > 0) {
                  if (blkmode) {
                      if (pos == end) {
                          refill();
                      }
                      if (end < 0) {
                          break;
                      }
                      int nread = (int) Math.min(remain, end - pos);
                      remain -= nread;
                      pos += nread;
                  } else {
                      int nread = (int) Math.min(remain, MAX_BLOCK_SIZE);
                      if ((nread = in.read(buf, 0, nread)) < 0) {
                          break;
                      }
                      remain -= nread;
                  }
              }
              return len - remain;
          }
  
          public int available() throws IOException {
              if (blkmode) {
                  if ((pos == end) && (unread == 0)) {
                      int n;
                      while ((n = readBlockHeader(false)) == 0) ;
                      switch (n) {
                          case HEADER_BLOCKED:
                              break;
  
                          case -1:
                              pos = 0;
                              end = -1;
                              break;
  
                          default:
                              pos = 0;
                              end = 0;
                              unread = n;
                              break;
                      }
                  }
                  // avoid unnecessary call to in.available() if possible
                  int unreadAvail = (unread > 0) ?
                      Math.min(in.available(), unread) : 0;
                  return (end >= 0) ? (end - pos) + unreadAvail : 0;
              } else {
                  return in.available();
              }
          }
  
          public void close() throws IOException {
              if (blkmode) {
                  pos = 0;
                  end = -1;
                  unread = 0;
              }
              in.close();
          }
  
          /**
           * Attempts to read len bytes into byte array b at offset off.  Returns
           * the number of bytes read, or -1 if the end of stream/block data has
           * been reached.  If copy is true, reads values into an intermediate
           * buffer before copying them to b (to avoid exposing a reference to
           * b).
           */
          int read(byte[] b, int off, int len, boolean copy) throws IOException {
              if (len == 0) {
                  return 0;
              } else if (blkmode) {
                  if (pos == end) {
                      refill();
                  }
                  if (end < 0) {
                      return -1;
                  }
                  int nread = Math.min(len, end - pos);
                  System.arraycopy(buf, pos, b, off, nread);
                  pos += nread;
                  return nread;
              } else if (copy) {
                  int nread = in.read(buf, 0, Math.min(len, MAX_BLOCK_SIZE));
                  if (nread > 0) {
                      System.arraycopy(buf, 0, b, off, nread);
                  }
                  return nread;
              } else {
                  return in.read(b, off, len);
              }
          }
  
          /* ----------------- primitive data input methods ------------------ */
          /*
           * The following methods are equivalent to their counterparts in
           * DataInputStream, except that they interpret data block boundaries
           * and read the requested data from within data blocks when in block
           * data mode.
           */
  
          public void readFully(byte[] b) throws IOException {
              readFully(b, 0, b.length, false);
          }
  
          public void readFully(byte[] b, int off, int len) throws IOException {
              readFully(b, off, len, false);
          }
  
          public void readFully(byte[] b, int off, int len, boolean copy)
              throws IOException
          {
              while (len > 0) {
                  int n = read(b, off, len, copy);
                  if (n < 0) {
                      throw new EOFException();
                  }
                  off += n;
                  len -= n;
              }
          }
  
          public int skipBytes(int n) throws IOException {
              return din.skipBytes(n);
          }
  
          public boolean readBoolean() throws IOException {
              int v = read();
              if (v < 0) {
                  throw new EOFException();
              }
              return (v != 0);
          }
  
          public byte readByte() throws IOException {
              int v = read();
              if (v < 0) {
                  throw new EOFException();
              }
              return (byte) v;
          }
  
          public int readUnsignedByte() throws IOException {
              int v = read();
              if (v < 0) {
                  throw new EOFException();
              }
              return v;
          }
  
          public char readChar() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 2);
              } else if (end - pos < 2) {
                  return din.readChar();
              }
              char v = Bits.getChar(buf, pos);
              pos += 2;
              return v;
          }
  
          public short readShort() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 2);
              } else if (end - pos < 2) {
                  return din.readShort();
              }
              short v = Bits.getShort(buf, pos);
              pos += 2;
              return v;
          }
  
          public int readUnsignedShort() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 2);
              } else if (end - pos < 2) {
                  return din.readUnsignedShort();
              }
              int v = Bits.getShort(buf, pos) & 0xFFFF;
              pos += 2;
              return v;
          }
  
          public int readInt() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 4);
              } else if (end - pos < 4) {
                  return din.readInt();
              }
              int v = Bits.getInt(buf, pos);
              pos += 4;
              return v;
          }
  
          public float readFloat() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 4);
              } else if (end - pos < 4) {
                  return din.readFloat();
              }
              float v = Bits.getFloat(buf, pos);
              pos += 4;
              return v;
          }
  
          public long readLong() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 8);
              } else if (end - pos < 8) {
                  return din.readLong();
              }
              long v = Bits.getLong(buf, pos);
              pos += 8;
              return v;
          }
  
          public double readDouble() throws IOException {
              if (!blkmode) {
                  pos = 0;
                  in.readFully(buf, 0, 8);
              } else if (end - pos < 8) {
                  return din.readDouble();
              }
              double v = Bits.getDouble(buf, pos);
              pos += 8;
              return v;
          }
  
          public String readUTF() throws IOException {
              return readUTFBody(readUnsignedShort());
          }
  
          @SuppressWarnings("deprecation")
          public String readLine() throws IOException {
              return din.readLine();      // deprecated, not worth optimizing
          }
  
          /* -------------- primitive data array input methods --------------- */
          /*
           * The following methods read in spans of primitive data values.
           * Though equivalent to calling the corresponding primitive read
           * methods repeatedly, these methods are optimized for reading groups
           * of primitive data values more efficiently.
           */
  
          void readBooleans(boolean[] v, int off, int len) throws IOException {
              int stop, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      int span = Math.min(endoff - off, MAX_BLOCK_SIZE);
                      in.readFully(buf, 0, span);
                      stop = off + span;
                      pos = 0;
                  } else if (end - pos < 1) {
                      v[off++] = din.readBoolean();
                      continue;
                  } else {
                      stop = Math.min(endoff, off + end - pos);
                  }
  
                  while (off < stop) {
                      v[off++] = Bits.getBoolean(buf, pos++);
                  }
              }
          }
  
          void readChars(char[] v, int off, int len) throws IOException {
              int stop, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 1);
                      in.readFully(buf, 0, span << 1);
                      stop = off + span;
                      pos = 0;
                  } else if (end - pos < 2) {
                      v[off++] = din.readChar();
                      continue;
                  } else {
                      stop = Math.min(endoff, off + ((end - pos) >> 1));
                  }
  
                  while (off < stop) {
                      v[off++] = Bits.getChar(buf, pos);
                      pos += 2;
                  }
              }
          }
  
          void readShorts(short[] v, int off, int len) throws IOException {
              int stop, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 1);
                      in.readFully(buf, 0, span << 1);
                      stop = off + span;
                      pos = 0;
                  } else if (end - pos < 2) {
                      v[off++] = din.readShort();
                      continue;
                  } else {
                      stop = Math.min(endoff, off + ((end - pos) >> 1));
                  }
  
                  while (off < stop) {
                      v[off++] = Bits.getShort(buf, pos);
                      pos += 2;
                  }
              }
          }
  
          void readInts(int[] v, int off, int len) throws IOException {
              int stop, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 2);
                      in.readFully(buf, 0, span << 2);
                      stop = off + span;
                      pos = 0;
                  } else if (end - pos < 4) {
                      v[off++] = din.readInt();
                      continue;
                  } else {
                      stop = Math.min(endoff, off + ((end - pos) >> 2));
                  }
  
                  while (off < stop) {
                      v[off++] = Bits.getInt(buf, pos);
                      pos += 4;
                  }
              }
          }
  
          void readFloats(float[] v, int off, int len) throws IOException {
              int span, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 2);
                      in.readFully(buf, 0, span << 2);
                      pos = 0;
                  } else if (end - pos < 4) {
                      v[off++] = din.readFloat();
                      continue;
                  } else {
                      span = Math.min(endoff - off, ((end - pos) >> 2));
                  }
  
                  bytesToFloats(buf, pos, v, off, span);
                  off += span;
                  pos += span << 2;
              }
          }
  
          void readLongs(long[] v, int off, int len) throws IOException {
              int stop, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 3);
                      in.readFully(buf, 0, span << 3);
                      stop = off + span;
                      pos = 0;
                  } else if (end - pos < 8) {
                      v[off++] = din.readLong();
                      continue;
                  } else {
                      stop = Math.min(endoff, off + ((end - pos) >> 3));
                  }
  
                  while (off < stop) {
                      v[off++] = Bits.getLong(buf, pos);
                      pos += 8;
                  }
              }
          }
  
          void readDoubles(double[] v, int off, int len) throws IOException {
              int span, endoff = off + len;
              while (off < endoff) {
                  if (!blkmode) {
                      span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 3);
                      in.readFully(buf, 0, span << 3);
                      pos = 0;
                  } else if (end - pos < 8) {
                      v[off++] = din.readDouble();
                      continue;
                  } else {
                      span = Math.min(endoff - off, ((end - pos) >> 3));
                  }
  
                  bytesToDoubles(buf, pos, v, off, span);
                  off += span;
                  pos += span << 3;
              }
          }
  
          /**
           * Reads in string written in "long" UTF format.  "Long" UTF format is
           * identical to standard UTF, except that it uses an 8 byte header
           * (instead of the standard 2 bytes) to convey the UTF encoding length.
           */
          String readLongUTF() throws IOException {
              return readUTFBody(readLong());
          }
  
          /**
           * Reads in the "body" (i.e., the UTF representation minus the 2-byte
           * or 8-byte length header) of a UTF encoding, which occupies the next
           * utflen bytes.
           */
          private String readUTFBody(long utflen) throws IOException {
              StringBuilder sbuf = new StringBuilder();
              if (!blkmode) {
                  end = pos = 0;
              }
  
              while (utflen > 0) {
                  int avail = end - pos;
                  if (avail >= 3 || (long) avail == utflen) {
                      utflen -= readUTFSpan(sbuf, utflen);
                  } else {
                      if (blkmode) {
                          // near block boundary, read one byte at a time
                          utflen -= readUTFChar(sbuf, utflen);
                      } else {
                          // shift and refill buffer manually
                          if (avail > 0) {
                              System.arraycopy(buf, pos, buf, 0, avail);
                          }
                          pos = 0;
                          end = (int) Math.min(MAX_BLOCK_SIZE, utflen);
                          in.readFully(buf, avail, end - avail);
                      }
                  }
              }
  
              return sbuf.toString();
          }
  
          /**
           * Reads span of UTF-encoded characters out of internal buffer
           * (starting at offset pos and ending at or before offset end),
           * consuming no more than utflen bytes.  Appends read characters to
           * sbuf.  Returns the number of bytes consumed.
           */
          private long readUTFSpan(StringBuilder sbuf, long utflen)
              throws IOException
          {
              int cpos = 0;
              int start = pos;
              int avail = Math.min(end - pos, CHAR_BUF_SIZE);
              // stop short of last char unless all of utf bytes in buffer
              int stop = pos + ((utflen > avail) ? avail - 2 : (int) utflen);
              boolean outOfBounds = false;
  
              try {
                  while (pos < stop) {
                      int b1, b2, b3;
                      b1 = buf[pos++] & 0xFF;
                      switch (b1 >> 4) {
                          case 0:
                          case 1:
                          case 2:
                          case 3:
                          case 4:
                          case 5:
                          case 6:
                          case 7:   // 1 byte format: 0xxxxxxx
                              cbuf[cpos++] = (char) b1;
                              break;
  
                          case 12:
                          case 13:  // 2 byte format: 110xxxxx 10xxxxxx
                              b2 = buf[pos++];
                              if ((b2 & 0xC0) != 0x80) {
                                  throw new UTFDataFormatException();
                              }
                              cbuf[cpos++] = (char) (((b1 & 0x1F) << 6) |
                                                     ((b2 & 0x3F) << 0));
                              break;
  
                          case 14:  // 3 byte format: 1110xxxx 10xxxxxx 10xxxxxx
                              b3 = buf[pos + 1];
                              b2 = buf[pos + 0];
                              pos += 2;
                              if ((b2 & 0xC0) != 0x80 || (b3 & 0xC0) != 0x80) {
                                  throw new UTFDataFormatException();
                              }
                              cbuf[cpos++] = (char) (((b1 & 0x0F) << 12) |
                                                     ((b2 & 0x3F) << 6) |
                                                     ((b3 & 0x3F) << 0));
                              break;
  
                          default:  // 10xx xxxx, 1111 xxxx
                              throw new UTFDataFormatException();
                      }
                  }
              } catch (ArrayIndexOutOfBoundsException ex) {
                  outOfBounds = true;
              } finally {
                  if (outOfBounds || (pos - start) > utflen) {
                      /*
                       * Fix for 4450867: if a malformed utf char causes the
                       * conversion loop to scan past the expected end of the utf
                       * string, only consume the expected number of utf bytes.
                       */
                      pos = start + (int) utflen;
                      throw new UTFDataFormatException();
                  }
              }
  
              sbuf.append(cbuf, 0, cpos);
              return pos - start;
          }
  
          /**
           * Reads in single UTF-encoded character one byte at a time, appends
           * the character to sbuf, and returns the number of bytes consumed.
           * This method is used when reading in UTF strings written in block
           * data mode to handle UTF-encoded characters which (potentially)
           * straddle block-data boundaries.
           */
          private int readUTFChar(StringBuilder sbuf, long utflen)
              throws IOException
          {
              int b1, b2, b3;
              b1 = readByte() & 0xFF;
              switch (b1 >> 4) {
                  case 0:
                  case 1:
                  case 2:
                  case 3:
                  case 4:
                  case 5:
                  case 6:
                  case 7:     // 1 byte format: 0xxxxxxx
                      sbuf.append((char) b1);
                      return 1;
  
                  case 12:
                  case 13:    // 2 byte format: 110xxxxx 10xxxxxx
                      if (utflen < 2) {
                          throw new UTFDataFormatException();
                      }
                      b2 = readByte();
                      if ((b2 & 0xC0) != 0x80) {
                          throw new UTFDataFormatException();
                      }
                      sbuf.append((char) (((b1 & 0x1F) << 6) |
                                          ((b2 & 0x3F) << 0)));
                      return 2;
  
                  case 14:    // 3 byte format: 1110xxxx 10xxxxxx 10xxxxxx
                      if (utflen < 3) {
                          if (utflen == 2) {
                              readByte();         // consume remaining byte
                          }
                          throw new UTFDataFormatException();
                      }
                      b2 = readByte();
                      b3 = readByte();
                      if ((b2 & 0xC0) != 0x80 || (b3 & 0xC0) != 0x80) {
                          throw new UTFDataFormatException();
                      }
                      sbuf.append((char) (((b1 & 0x0F) << 12) |
                                          ((b2 & 0x3F) << 6) |
                                          ((b3 & 0x3F) << 0)));
                      return 3;
  
                  default:   // 10xx xxxx, 1111 xxxx
                      throw new UTFDataFormatException();
              }
          }
  
          /**
           * Returns the number of bytes read from the input stream.
           * @return the number of bytes read from the input stream
           */
          long getBytesRead() {
              return in.getBytesRead();
          }
      }
  
      /**
       * Unsynchronized table which tracks wire handle to object mappings, as
       * well as ClassNotFoundExceptions associated with deserialized objects.
       * This class implements an exception-propagation algorithm for
       * determining which objects should have ClassNotFoundExceptions associated
       * with them, taking into account cycles and discontinuities (e.g., skipped
       * fields) in the object graph.
       *
       * <p>General use of the table is as follows: during deserialization, a
       * given object is first assigned a handle by calling the assign method.
       * This method leaves the assigned handle in an "open" state, wherein
       * dependencies on the exception status of other handles can be registered
       * by calling the markDependency method, or an exception can be directly
       * associated with the handle by calling markException.  When a handle is
       * tagged with an exception, the HandleTable assumes responsibility for
       * propagating the exception to any other objects which depend
       * (transitively) on the exception-tagged object.
       *
       * <p>Once all exception information/dependencies for the handle have been
       * registered, the handle should be "closed" by calling the finish method
       * on it.  The act of finishing a handle allows the exception propagation
       * algorithm to aggressively prune dependency links, lessening the
       * performance/memory impact of exception tracking.
       *
       * <p>Note that the exception propagation algorithm used depends on handles
       * being assigned/finished in LIFO order; however, for simplicity as well
       * as memory conservation, it does not enforce this constraint.
       */
      // REMIND: add full description of exception propagation algorithm?
      private static class HandleTable {
  
          /* status codes indicating whether object has associated exception */
          private static final byte STATUS_OK = 1;
          private static final byte STATUS_UNKNOWN = 2;
          private static final byte STATUS_EXCEPTION = 3;
  
          /** array mapping handle -> object status */
          byte[] status;
          /** array mapping handle -> object/exception (depending on status) */
          Object[] entries;
          /** array mapping handle -> list of dependent handles (if any) */
          HandleList[] deps;
          /** lowest unresolved dependency */
          int lowDep = -1;
          /** number of handles in table */
          int size = 0;
  
          /**
           * Creates handle table with the given initial capacity.
           */
          HandleTable(int initialCapacity) {
              status = new byte[initialCapacity];
              entries = new Object[initialCapacity];
              deps = new HandleList[initialCapacity];
          }
  
          /**
           * Assigns next available handle to given object, and returns assigned
           * handle.  Once object has been completely deserialized (and all
           * dependencies on other objects identified), the handle should be
           * "closed" by passing it to finish().
           */
          int assign(Object obj) {
              if (size >= entries.length) {
                  grow();
              }
              status[size] = STATUS_UNKNOWN;
              entries[size] = obj;
              return size++;
          }
  
          /**
           * Registers a dependency (in exception status) of one handle on
           * another.  The dependent handle must be "open" (i.e., assigned, but
           * not finished yet).  No action is taken if either dependent or target
           * handle is NULL_HANDLE.
           */
          void markDependency(int dependent, int target) {
              if (dependent == NULL_HANDLE || target == NULL_HANDLE) {
                  return;
              }
              switch (status[dependent]) {
  
                  case STATUS_UNKNOWN:
                      switch (status[target]) {
                          case STATUS_OK:
                              // ignore dependencies on objs with no exception
                              break;
  
                          case STATUS_EXCEPTION:
                              // eagerly propagate exception
                              markException(dependent,
                                  (ClassNotFoundException) entries[target]);
                              break;
  
                          case STATUS_UNKNOWN:
                              // add to dependency list of target
                              if (deps[target] == null) {
                                  deps[target] = new HandleList();
                              }
                              deps[target].add(dependent);
  
                              // remember lowest unresolved target seen
                              if (lowDep < 0 || lowDep > target) {
                                  lowDep = target;
                              }
                              break;
  
                          default:
                              throw new InternalError();
                      }
                      break;
  
                  case STATUS_EXCEPTION:
                      break;
  
                  default:
                      throw new InternalError();
              }
          }
  
          /**
           * Associates a ClassNotFoundException (if one not already associated)
           * with the currently active handle and propagates it to other
           * referencing objects as appropriate.  The specified handle must be
           * "open" (i.e., assigned, but not finished yet).
           */
          void markException(int handle, ClassNotFoundException ex) {
              switch (status[handle]) {
                  case STATUS_UNKNOWN:
                      status[handle] = STATUS_EXCEPTION;
                      entries[handle] = ex;
  
                      // propagate exception to dependents
                      HandleList dlist = deps[handle];
                      if (dlist != null) {
                          int ndeps = dlist.size();
                          for (int i = 0; i < ndeps; i++) {
                              markException(dlist.get(i), ex);
                          }
                          deps[handle] = null;
                      }
                      break;
  
                  case STATUS_EXCEPTION:
                      break;
  
                  default:
                      throw new InternalError();
              }
          }
  
          /**
           * Marks given handle as finished, meaning that no new dependencies
           * will be marked for handle.  Calls to the assign and finish methods
           * must occur in LIFO order.
           */
          void finish(int handle) {
              int end;
              if (lowDep < 0) {
                  // no pending unknowns, only resolve current handle
                  end = handle + 1;
              } else if (lowDep >= handle) {
                  // pending unknowns now clearable, resolve all upward handles
                  end = size;
                  lowDep = -1;
              } else {
                  // unresolved backrefs present, can't resolve anything yet
                  return;
              }
  
              // change STATUS_UNKNOWN -> STATUS_OK in selected span of handles
              for (int i = handle; i < end; i++) {
                  switch (status[i]) {
                      case STATUS_UNKNOWN:
                          status[i] = STATUS_OK;
                          deps[i] = null;
                          break;
  
                      case STATUS_OK:
                      case STATUS_EXCEPTION:
                          break;
  
                      default:
                          throw new InternalError();
                  }
              }
          }
  
          /**
           * Assigns a new object to the given handle.  The object previously
           * associated with the handle is forgotten.  This method has no effect
           * if the given handle already has an exception associated with it.
           * This method may be called at any time after the handle is assigned.
           */
          void setObject(int handle, Object obj) {
              switch (status[handle]) {
                  case STATUS_UNKNOWN:
                  case STATUS_OK:
                      entries[handle] = obj;
                      break;
  
                  case STATUS_EXCEPTION:
                      break;
  
                  default:
                      throw new InternalError();
              }
          }
  
          /**
           * Looks up and returns object associated with the given handle.
           * Returns null if the given handle is NULL_HANDLE, or if it has an
           * associated ClassNotFoundException.
           */
          Object lookupObject(int handle) {
              return (handle != NULL_HANDLE &&
                      status[handle] != STATUS_EXCEPTION) ?
                  entries[handle] : null;
          }
  
          /**
           * Looks up and returns ClassNotFoundException associated with the
           * given handle.  Returns null if the given handle is NULL_HANDLE, or
           * if there is no ClassNotFoundException associated with the handle.
           */
          ClassNotFoundException lookupException(int handle) {
              return (handle != NULL_HANDLE &&
                      status[handle] == STATUS_EXCEPTION) ?
                  (ClassNotFoundException) entries[handle] : null;
          }
  
          /**
           * Resets table to its initial state.
           */
          void clear() {
              Arrays.fill(status, 0, size, (byte) 0);
              Arrays.fill(entries, 0, size, null);
              Arrays.fill(deps, 0, size, null);
              lowDep = -1;
              size = 0;
          }
  
          /**
           * Returns number of handles registered in table.
           */
          int size() {
              return size;
          }
  
          /**
           * Expands capacity of internal arrays.
           */
          private void grow() {
              int newCapacity = (entries.length << 1) + 1;
  
              byte[] newStatus = new byte[newCapacity];
              Object[] newEntries = new Object[newCapacity];
              HandleList[] newDeps = new HandleList[newCapacity];
  
              System.arraycopy(status, 0, newStatus, 0, size);
              System.arraycopy(entries, 0, newEntries, 0, size);
              System.arraycopy(deps, 0, newDeps, 0, size);
  
              status = newStatus;
              entries = newEntries;
              deps = newDeps;
          }
  
          /**
           * Simple growable list of (integer) handles.
           */
          private static class HandleList {
              private int[] list = new int[4];
              private int size = 0;
  
              public HandleList() {
              }
  
              public void add(int handle) {
                  if (size >= list.length) {
                      int[] newList = new int[list.length << 1];
                      System.arraycopy(list, 0, newList, 0, list.length);
                      list = newList;
                  }
                  list[size++] = handle;
              }
  
              public int get(int index) {
                  if (index >= size) {
                      throw new ArrayIndexOutOfBoundsException();
                  }
                  return list[index];
              }
  
              public int size() {
                  return size;
              }
          }
      }
  
      /**
       * Method for cloning arrays in case of using unsharing reading
       */
      private static Object cloneArray(Object array) {
          if (array instanceof Object[]) {
              return ((Object[]) array).clone();
          } else if (array instanceof boolean[]) {
              return ((boolean[]) array).clone();
          } else if (array instanceof byte[]) {
              return ((byte[]) array).clone();
          } else if (array instanceof char[]) {
              return ((char[]) array).clone();
          } else if (array instanceof double[]) {
              return ((double[]) array).clone();
          } else if (array instanceof float[]) {
              return ((float[]) array).clone();
          } else if (array instanceof int[]) {
              return ((int[]) array).clone();
          } else if (array instanceof long[]) {
              return ((long[]) array).clone();
          } else if (array instanceof short[]) {
              return ((short[]) array).clone();
          } else {
              throw new AssertionError();
          }
      }
  
      // Android-removed: Logic related to ObjectStreamClassValidator, unused on Android
      /*
      private void validateDescriptor(ObjectStreamClass descriptor) {
          ObjectStreamClassValidator validating = validator;
          if (validating != null) {
              validating.validateDescriptor(descriptor);
          }
      }
  
      // controlled access to ObjectStreamClassValidator
      private volatile ObjectStreamClassValidator validator;
  
      private static void setValidator(ObjectInputStream ois, ObjectStreamClassValidator validator) {
          ois.validator = validator;
      }
      static {
          SharedSecrets.setJavaObjectInputStreamAccess(ObjectInputStream::setValidator);
      }
      */
  }
  