objectinputstream.java

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/* ObjectInputStream.java -- Class used to read serialized objects
   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.io;

import java.lang.reflect.Array;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.security.PrivilegedAction;
import java.security.AccessController;
import java.util.Arrays;
import java.util.Hashtable;
import java.util.Vector;


import gnu.java.io.ObjectIdentityWrapper;
import gnu.java.lang.reflect.TypeSignature;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

import gnu.classpath.Configuration;

public class ObjectInputStream extends InputStream
  implements ObjectInput, ObjectStreamConstants
{
  /**
   * Creates a new <code>ObjectInputStream</code> that will do all of
   * its reading from <code>in</code>.  This method also checks
   * the stream by reading the header information (stream magic number
   * and stream version).
   *
   * @exception IOException Reading stream header from underlying
   * stream cannot be completed.
   *
   * @exception StreamCorruptedException An invalid stream magic
   * number or stream version was read from the stream.
   *
   * @see #readStreamHeader()
   */
  public ObjectInputStream(InputStream in)
    throws IOException, StreamCorruptedException
  {
    if (Configuration.DEBUG)
      {
	String val = System.getProperty("gcj.dumpobjects");
	if (dump == false && val != null && !val.equals(""))
	  {
	    dump = true;
	    System.out.println ("Serialization debugging enabled");
	  }
	else if (dump == true && (val == null || val.equals("")))
	  {
	    dump = false;
	    System.out.println ("Serialization debugging disabled");
	  }
      }

    this.resolveEnabled = false;
    this.isDeserializing = false;
    this.blockDataPosition = 0;
    this.blockDataBytes = 0;
    this.blockData = new byte[BUFFER_SIZE];
    this.blockDataInput = new DataInputStream(this);
    this.realInputStream = new DataInputStream(in);
    this.nextOID = baseWireHandle;
    this.objectLookupTable = new Hashtable();
    this.validators = new Vector();
    this.classLookupTable = new Hashtable();
    setBlockDataMode(true);
    readStreamHeader();
  }


  /**
   * Returns the next deserialized object read from the underlying stream.
   *
   * This method can be overriden by a class by implementing
   * <code>private void readObject (ObjectInputStream)</code>.
   *
   * If an exception is thrown from this method, the stream is left in
   * an undefined state.
   *
   * @exception ClassNotFoundException The class that an object being
   * read in belongs to cannot be found.
   *
   * @exception IOException Exception from underlying
   * <code>InputStream</code>.
   */
  public final Object readObject() throws ClassNotFoundException, IOException
  {
    if (this.useSubclassMethod)
      return readObjectOverride();

    boolean was_deserializing;

    Object ret_val;
    was_deserializing = this.isDeserializing;

    boolean is_consumed = false;
    boolean old_mode = setBlockDataMode(false);

    this.isDeserializing = true;

    byte marker = this.realInputStream.readByte();
    if(dump) dumpElement("MARKER: 0x" + Integer.toHexString(marker) + " ");

    try
      {
	switch (marker)
	  {
	  case TC_ENDBLOCKDATA:
	    {
	      ret_val = null;
	      is_consumed = true;
	      break;
	    }

	  case TC_BLOCKDATA:
	  case TC_BLOCKDATALONG:
	    {
	      if (marker == TC_BLOCKDATALONG)
		if(dump) dumpElementln("BLOCKDATALONG");
	      else
		if(dump) dumpElementln("BLOCKDATA");
	      readNextBlock(marker);
	      throw new StreamCorruptedException("Unexpected blockData");
	    }

	  case TC_NULL:
	    {
	      if(dump) dumpElementln("NULL");
	      ret_val = null;
	      break;
	    }

	  case TC_REFERENCE:
	    {
	      if(dump) dumpElement("REFERENCE ");
	      Integer oid = new Integer(this.realInputStream.readInt());
	      if(dump) dumpElementln(Integer.toHexString(oid.intValue()));
	      ret_val = ((ObjectIdentityWrapper)
			 this.objectLookupTable.get(oid)).object;
	      break;
	    }

	  case TC_CLASS:
	    {
	      if(dump) dumpElementln("CLASS");
	      ObjectStreamClass osc = (ObjectStreamClass)readObject();
	      Class clazz = osc.forClass();
	      assignNewHandle(clazz);
	      ret_val = clazz;
	      break;
	    }

	  case TC_PROXYCLASSDESC:
	    {
	      if(dump) dumpElementln("PROXYCLASS");
	      int n_intf = this.realInputStream.readInt();
	      String[] intfs = new String[n_intf];
	      for (int i = 0; i < n_intf; i++)
		{
		  intfs[i] = this.realInputStream.readUTF();
		  System.out.println(intfs[i]);
		}
	      
	      boolean oldmode = setBlockDataMode(true);
	      Class cl = resolveProxyClass(intfs);
	      setBlockDataMode(oldmode);
	      
	      ObjectStreamClass osc = lookupClass(cl);
	      assignNewHandle(osc);
	      
	      if (!is_consumed)
		{
		  byte b = this.realInputStream.readByte();
		  if (b != TC_ENDBLOCKDATA)
		    throw new IOException("Data annotated to class was not consumed." + b);
		}
	      else
		is_consumed = false;
	      ObjectStreamClass superosc = (ObjectStreamClass)readObject();
	      osc.setSuperclass(superosc);
	      ret_val = osc;
	      break;
	    }

	  case TC_CLASSDESC:
	    {
	      ObjectStreamClass osc = readClassDescriptor();
	      
	      if (!is_consumed)
		{
		  byte b = this.realInputStream.readByte();
		  if (b != TC_ENDBLOCKDATA)
		    throw new IOException("Data annotated to class was not consumed." + b);
		}
	      else
		is_consumed = false;
	      
	      osc.setSuperclass ((ObjectStreamClass)readObject());
	      ret_val = osc;
	      break;
	    }

	  case TC_STRING:
	  case TC_LONGSTRING:
	    {
	      if(dump) dumpElement("STRING=");
	      String s = this.realInputStream.readUTF();
	      if(dump) dumpElementln(s);
	      ret_val = processResolution(null, s, assignNewHandle(s));
	      break;
	    }

	  case TC_ARRAY:
	    {
	      if(dump) dumpElementln("ARRAY");
	      ObjectStreamClass osc = (ObjectStreamClass)readObject();
	      Class componentType = osc.forClass().getComponentType();
	      if(dump) dumpElement("ARRAY LENGTH=");
	      int length = this.realInputStream.readInt();
	      if(dump) dumpElementln (length + "; COMPONENT TYPE=" + componentType);
	      Object array = Array.newInstance(componentType, length);
	      int handle = assignNewHandle(array);
	      readArrayElements(array, componentType);
	      if(dump)
	        for (int i = 0, len = Array.getLength(array); i < len; i++)
		  dumpElementln("  ELEMENT[" + i + "]=" + Array.get(array, i));
	      ret_val = processResolution(null, array, handle);
	      break;
	    }

	  case TC_OBJECT:
	    {
	      if(dump) dumpElementln("OBJECT");
	      ObjectStreamClass osc = (ObjectStreamClass)readObject();
	      Class clazz = osc.forClass();
	      
	      if (!osc.realClassIsSerializable)
		throw new NotSerializableException
		  (clazz + " is not Serializable, and thus cannot be deserialized.");
	      
	      if (osc.realClassIsExternalizable)
		{
		  Externalizable obj = null;
		  
		  try
		    {
		      obj = (Externalizable)clazz.newInstance();
		    }
		  catch (InstantiationException e)
		    {
		      throw new ClassNotFoundException
			("Instance of " + clazz + " could not be created");
		    }
		  catch (IllegalAccessException e)
		    {
		      throw new ClassNotFoundException
			("Instance of " + clazz + " could not be created because class or "
			 + "zero-argument constructor is not accessible");
		    }
		  catch (NoSuchMethodError e)
		    {
		      throw new ClassNotFoundException
			("Instance of " + clazz
			 + " could not be created because zero-argument constructor is not defined");
		    }
		  
		  int handle = assignNewHandle(obj);
		  
		  boolean read_from_blocks = ((osc.getFlags() & SC_BLOCK_DATA) != 0);
		  
		  boolean oldmode = this.readDataFromBlock;
		  if (read_from_blocks)
		    setBlockDataMode(true);
		  
		  obj.readExternal(this);
		  
		  if (read_from_blocks)
		    setBlockDataMode(oldmode);
		  
		  ret_val = processResolution(osc, obj, handle);
		  break;
		} // end if (osc.realClassIsExternalizable)

	      Object obj = newObject(clazz, osc.firstNonSerializableParent);
	      
	      int handle = assignNewHandle(obj);
	      this.currentObject = obj;
	      ObjectStreamClass[] hierarchy =
		inputGetObjectStreamClasses(clazz);
	      
	      for (int i = 0; i < hierarchy.length; i++)
		{
		  this.currentObjectStreamClass = hierarchy[i];
		  
		  if(dump) dumpElementln("Reading fields of " + this.currentObjectStreamClass.getName ());

		  // XXX: should initialize fields in classes in the hierarchy
		  // that aren't in the stream
		  // should skip over classes in the stream that aren't in the
		  // real classes hierarchy
		  
		  Method readObjectMethod = this.currentObjectStreamClass.readObjectMethod;
		  if (readObjectMethod != null)
		    {
		      fieldsAlreadyRead = false;
		      boolean oldmode = setBlockDataMode(true);
		      callReadMethod(readObjectMethod, this.currentObjectStreamClass.forClass(), obj);
		      setBlockDataMode(oldmode);
		      if(dump) dumpElement("ENDBLOCKDATA? ");
		      try
			{
			  // FIXME: XXX: This try block is to catch EOF which is
			  // thrown for some objects.  That indicates a bug in the logic.
			  if (this.realInputStream.readByte() != TC_ENDBLOCKDATA)
			    throw new IOException
			      ("No end of block data seen for class with readObject (ObjectInputStream) method.");
			  if(dump) dumpElementln("yes");
			}
		      catch (EOFException e)
			{
			  if(dump) dumpElementln("no, got EOFException");
			}
		      catch (IOException e)
			{
			  if(dump) dumpElementln("no, got IOException");
			}
		    }
		  else
		    {
		      readFields(obj, currentObjectStreamClass);
		    }
		}

	      this.currentObject = null;
	      this.currentObjectStreamClass = null;
	      ret_val = processResolution(osc, obj, handle);
	      break;
	    }

	  case TC_RESET:
	    if(dump) dumpElementln("RESET");
	    clearHandles();
	    ret_val = readObject();
	    break;

	  case TC_EXCEPTION:
	    {
	      if(dump) dumpElement("EXCEPTION=");
	      Exception e = (Exception)readObject();
	      if(dump) dumpElementln(e.toString());
	      clearHandles();
	      throw new WriteAbortedException("Exception thrown during writing of stream", e);
	    }

	  default:
	    throw new IOException("Unknown marker on stream: " + marker);
	  }
      }
    finally
      {
	setBlockDataMode(old_mode);
	
	this.isDeserializing = was_deserializing;
	
	if (! was_deserializing)
	  {
	    if (validators.size() > 0)
	      invokeValidators();
	  }
      }
    
    return ret_val;
  }

  /**
   * This method reads a class descriptor from the real input stream
   * and use these data to create a new instance of ObjectStreamClass.
   * Fields are sorted and ordered for the real read which occurs for
   * each instance of the described class. Be aware that if you call that
   * method you must ensure that the stream is synchronized, in the other
   * case it may be completely desynchronized.
   *
   * @return A new instance of ObjectStreamClass containing the freshly
   * created descriptor.
   * @throws ClassNotFoundException if the required class to build the
   * descriptor has not been found in the system.
   * @throws IOException An input/output error occured.
   * @throws InvalidClassException If there was a compatibility problem
   * between the class present in the system and the serialized class.
   */
  protected ObjectStreamClass readClassDescriptor()
    throws ClassNotFoundException, IOException
  {
    if(dump) dumpElement("CLASSDESC NAME=");
    String name = this.realInputStream.readUTF();
    if(dump) dumpElement(name + "; UID=");
    long uid = this.realInputStream.readLong ();
    if(dump) dumpElement(Long.toHexString(uid) + "; FLAGS=");
    byte flags = this.realInputStream.readByte ();
    if(dump) dumpElement(Integer.toHexString(flags) + "; FIELD COUNT=");
    short field_count = this.realInputStream.readShort();
    if(dump) dumpElementln(Short.toString(field_count));
    ObjectStreamField[] fields = new ObjectStreamField[field_count];
    ObjectStreamClass osc = new ObjectStreamClass(name, uid,
						  flags, fields);
    assignNewHandle(osc);

    ClassLoader currentLoader = currentLoader();
	      
    for (int i = 0; i < field_count; i++)
      {
	if(dump) dumpElement("  TYPE CODE=");
	char type_code = (char)this.realInputStream.readByte();
	if(dump) dumpElement(type_code + "; FIELD NAME=");
	String field_name = this.realInputStream.readUTF();
	if(dump) dumpElementln(field_name);
	String class_name;
		  
	// If the type code is an array or an object we must
	// decode a String here. In the other case we convert
	// the type code and pass it to ObjectStreamField.
	// Type codes are decoded by gnu.java.lang.reflect.TypeSignature.
	if (type_code == 'L' || type_code == '[')