J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1998-2004 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. |
| 8 | * |
| 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 12 | * version 2 for more details (a copy is included in the LICENSE file that |
| 13 | * accompanied this code). |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License version |
| 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 18 | * |
| 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 21 | * have any questions. |
| 22 | */ |
| 23 | |
| 24 | /* |
| 25 | * |
| 26 | */ |
| 27 | |
| 28 | import java.io.*; |
| 29 | import java.util.Vector; |
| 30 | import java.util.Stack; |
| 31 | import java.util.Hashtable; |
| 32 | import java.lang.Math; |
| 33 | import java.lang.reflect.InvocationTargetException; |
| 34 | import java.lang.reflect.Method; |
| 35 | import java.lang.reflect.Modifier; |
| 36 | |
| 37 | /** |
| 38 | * This abstract class enables one to subclass ObjectInputStream |
| 39 | * for the purpose of re-implementing serialization while preserving the |
| 40 | * existing public serialization API. A complimentary subclass of |
| 41 | * AbstractObjectInputStream must also be implemented.<p> |
| 42 | * |
| 43 | * Since serialization must override java access rules in order to |
| 44 | * access private, protected and package accessible Serializable fields, |
| 45 | * only trusted classes are allowed to subclass AbstractObjectInputStream. |
| 46 | * Subclasses of AbstractObjectInputStream must define SerializablePermission |
| 47 | * "enableAbstractSubclass" within a security policy file or this |
| 48 | * constructor will throw a SecurityException. Implementations of this |
| 49 | * class should protect themselves from being subclassed in a way that will |
| 50 | * provide access to object references and other sensitive info. |
| 51 | * Specifically, readObjectOverride() should be made final. |
| 52 | * <p> |
| 53 | * |
| 54 | * A subclass of AbstractObjectInputStream deserializes primitive data and |
| 55 | * objects previously written by a subclass of AbstractObjectOutputStream. |
| 56 | * The subclass ensures that the types of all objects in the graph created |
| 57 | * from the stream match the classes present in the Java Virtual Machine. |
| 58 | * Classes are loaded as required using the standard mechanisms. <p> |
| 59 | * |
| 60 | * Only objects that support the java.io.Serializable or |
| 61 | * java.io.Externalizable interface can be read from streams. |
| 62 | * |
| 63 | * The method <STRONG>readObjectOverride</STRONG> is used to read an object |
| 64 | * from the stream. Java's safe casting should be used to get the |
| 65 | * desired type. In Java, strings and arrays are objects and are |
| 66 | * treated as objects during serialization. When read with readObject() |
| 67 | * they need to be cast to the expected type.<p> |
| 68 | * |
| 69 | * Primitive data types can be read from the stream using the appropriate |
| 70 | * method on DataInput. <p> |
| 71 | * |
| 72 | * The default deserialization mechanism for objects restores the |
| 73 | * contents of each field to the value and type it had when it was written. |
| 74 | * References to other objects cause those |
| 75 | * objects to be read from the stream as necessary. Graphs of objects |
| 76 | * are restored correctly using a reference sharing mechanism. New |
| 77 | * objects are always allocated when deserializing, which prevents |
| 78 | * existing objects from being overwritten. <p> |
| 79 | * |
| 80 | * Reading an object is analogous to running the constructors of a new |
| 81 | * object. Memory is allocated for the object and initialized to zero |
| 82 | * (NULL). No-arg constructors are invoked for the first non-serializable |
| 83 | * super class and then the fields of the serializable classes are |
| 84 | * restored from the stream starting with the serializable class closest to |
| 85 | * java.lang.object and finishing with the object's most specifiec |
| 86 | * class. <p> |
| 87 | * |
| 88 | * Classes control how they are serialized by implementing either the |
| 89 | * java.io.Serializable or java.io.Externalizable interfaces.<P> |
| 90 | * |
| 91 | * Implementing the Serializable interface allows object serialization |
| 92 | * to save and restore the entire state of the object and it allows |
| 93 | * classes to evolve between the time the stream is written and the time it is |
| 94 | * read. It automatically traverses references between objects, |
| 95 | * saving and restoring entire graphs. |
| 96 | * |
| 97 | * Serializable classes that require special handling during the |
| 98 | * serialization and deserialization process should implement both |
| 99 | * of these methods:<p> |
| 100 | * |
| 101 | * <PRE> |
| 102 | * private void writeObject(java.io.ObjectOutputStream stream) |
| 103 | * throws IOException; |
| 104 | * private void readObject(java.io.ObjectInputStream stream) |
| 105 | * throws IOException, ClassNotFoundException; |
| 106 | * </PRE><p> |
| 107 | * |
| 108 | * The readObject method is responsible for reading and restoring the |
| 109 | * state of the object for its particular class using data written to |
| 110 | * the stream by the corresponding writeObject method. The method |
| 111 | * does not need to concern itself with the state belonging to its |
| 112 | * superclasses or subclasses. State is restored by reading data from |
| 113 | * the ObjectInputStream for the individual fields and making |
| 114 | * assignments to the appropriate fields of the object. Reading |
| 115 | * primitive data types is supported by DataInput. <p> |
| 116 | * |
| 117 | * Serialization does not read or assign values to the fields of any |
| 118 | * object that does not implement the java.io.Serializable interface. |
| 119 | * Subclasses of Objects that are not serializable can be |
| 120 | * serializable. In this case the non-serializable class must have an |
| 121 | * accessible no-arg constructor to allow its fields to be initialized. |
| 122 | * In this case it is the responsibility of the subclass to save and restore |
| 123 | * the state of the non-serializable class. It is frequently the case that |
| 124 | * the fields of that class are accessible (public, package, or |
| 125 | * protected) or that there are get and set methods that can be used |
| 126 | * to restore the state. <p> |
| 127 | * |
| 128 | * Implementing the Externalizable interface allows the object to |
| 129 | * assume complete control over the contents and format of the object's |
| 130 | * serialized form. The methods of the Externalizable interface, |
| 131 | * writeExternal and readExternal, are called to save and restore the |
| 132 | * objects state. When implemented by a class they can write and read |
| 133 | * their own state using all of the methods of ObjectOutput and |
| 134 | * ObjectInput. It is the responsibility of the objects to handle any |
| 135 | * versioning that occurs. |
| 136 | * |
| 137 | * @author Joe Fialli |
| 138 | * |
| 139 | * @see java.io.ObjectInputStream |
| 140 | * @see java.io.DataInput |
| 141 | * @see java.io.Serializable |
| 142 | * @see java.io.Externalizable |
| 143 | * @see java.io.ext.AbstractObjectOutputStream |
| 144 | * @since JDK1.2 |
| 145 | */ |
| 146 | abstract public class AbstractObjectInputStream extends ObjectInputStream |
| 147 | { |
| 148 | protected InputStream in; |
| 149 | /** |
| 150 | * Create an ObjectInputStream that reads from the specified InputStream.<p> |
| 151 | * |
| 152 | * Add the following line to the security policy file to enable |
| 153 | * subclassing. |
| 154 | * |
| 155 | * <PRE> |
| 156 | * permission SerializablePermission "enableAbstractSubclass" ; |
| 157 | * </PRE><p> |
| 158 | * |
| 159 | * @exception StreamCorruptedException The version or magic number are incorrect. |
| 160 | * @exception IOException An exception occurred in the underlying stream. |
| 161 | * @exception SecurityException if subclass does not have SerializablePermiision |
| 162 | * "enableAbstractSubclass". |
| 163 | */ |
| 164 | public AbstractObjectInputStream(InputStream in) |
| 165 | throws IOException, StreamCorruptedException |
| 166 | { |
| 167 | this.in = in; |
| 168 | } |
| 169 | |
| 170 | abstract public void close() throws IOException; |
| 171 | |
| 172 | /***************************************************************/ |
| 173 | /* Read an object from the stream. */ |
| 174 | |
| 175 | /** |
| 176 | * Read an object from the ObjectInputStream.<p> |
| 177 | * |
| 178 | * NOTE: The override method of this class should have the modifier final.<p> |
| 179 | * |
| 180 | * Default deserializing for a class can be |
| 181 | * overriden by defining a readObject method for the Serializable class. |
| 182 | * Objects referenced by this object are read transitively so |
| 183 | * that a complete equivalent graph of objects is reconstructed by |
| 184 | * readObject. <p> |
| 185 | * |
| 186 | * The root object is completely restored when all of its fields |
| 187 | * and the objects it references are completely restored. At this |
| 188 | * point the object validation callbacks are executed in order |
| 189 | * based on their registered priorities. The callbacks are |
| 190 | * registered by objects (in the readObject special methods) |
| 191 | * as they are individually restored. <p> |
| 192 | * |
| 193 | * For security's sake, any overrides of this method should be final. |
| 194 | * Serialization typically needs to disable java access rules |
| 195 | * to serialize private, protected and package accessible Serializable |
| 196 | * fields. This method gets called for ALL Serializable objects. |
| 197 | * |
| 198 | * @exception java.lang.ClassNotFoundException Class of a serialized object |
| 199 | * cannot be found. |
| 200 | * @exception InvalidClassException Something is wrong with a class used by |
| 201 | * serialization. |
| 202 | * @exception StreamCorruptedException Control information in the |
| 203 | * stream is inconsistent. |
| 204 | * @exception OptionalDataException Primitive data was found in the |
| 205 | * stream instead of objects. |
| 206 | * @exception IOException Any of the usual Input/Output related exceptions. |
| 207 | * |
| 208 | * @see java.io.ObjectInputStream#resolveObject(Object) |
| 209 | * @see java.io.Resolvable |
| 210 | * @see java.io.Externalizable |
| 211 | * @see java.io.ObjectInputValidation |
| 212 | * @see #registerValidation(ObjectInputValidation, int) |
| 213 | * @see java.io.ObjectInputStream#resolveClass(ObjectStreamClass) |
| 214 | */ |
| 215 | protected Object readObjectOverride() |
| 216 | throws OptionalDataException, ClassNotFoundException, IOException { |
| 217 | return null; |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * Read the Serializable fields of the current object from this stream.<p> |
| 222 | * |
| 223 | * Note: The object being deserialized is not passed to this method. |
| 224 | * For security purposes, the initial implementation maintained |
| 225 | * the state of the last object to be read by readObject |
| 226 | * only allowed this method to be invoked for this object.<p> |
| 227 | * |
| 228 | * @exception NotActiveException Thrown if a readObject method is not |
| 229 | * active. |
| 230 | * @exception ClassNotFoundException if no corresponding local class can be |
| 231 | * found in the local JVM. |
| 232 | */ |
| 233 | abstract public void defaultReadObject() |
| 234 | throws IOException, ClassNotFoundException, NotActiveException; |
| 235 | |
| 236 | /** |
| 237 | * Enable allocation for subclass reimplementing serialization.<p> |
| 238 | * |
| 239 | * Note: Default allocation does not have the java access priviledges |
| 240 | * to invoke package and protected constructors.<p> |
| 241 | * |
| 242 | * Security alert: this JVM native method is private within ObjectInputStream; however, |
| 243 | * it was anticipated that re-implementors of serialization would need |
| 244 | * access to this method. Is this allocator considered a security problem? <p> |
| 245 | * |
| 246 | * @param ctorClass is the same class or a superclass of <STRONG>ofClass</STRONG> |
| 247 | * @param ofClass the type of the object to allocate. |
| 248 | * @return an object of <STRONG>ofClass</STRONG> type. |
| 249 | * |
| 250 | * @exception IllegalAccessException if no-arg constructor of |
| 251 | * <STRONG>ctorClass</STRONG> is not accessible from |
| 252 | * <STRONG>ofClass</STRONG>. |
| 253 | * @exception InstantiationException TBD. |
| 254 | */ |
| 255 | final protected native Object |
| 256 | allocateNewObject(Class ofClass, Class ctorClass) |
| 257 | throws InstantiationException, IllegalAccessException; |
| 258 | |
| 259 | /** |
| 260 | * Enable allocation for subclass reimplementing serialization.<p> |
| 261 | * |
| 262 | * Note: Default allocation does not have the java access priviledges |
| 263 | * to invoke package and protected constructors.<p> |
| 264 | * |
| 265 | * Security alert: this JVM native method is private within ObjectInputStream; however, |
| 266 | * it was anticipated that re-implementors of serialization would need |
| 267 | * access to this method. Is this allocator considered a security problem?<p> |
| 268 | * |
| 269 | * |
| 270 | * @exception IllegalAccessException TBD. |
| 271 | * @exception InstantiationException TBD. |
| 272 | */ |
| 273 | final protected native Object |
| 274 | allocateNewArray(Class componentClass, int length) |
| 275 | throws InstantiationException, IllegalAccessException; |
| 276 | |
| 277 | /** |
| 278 | * Reads the Serializable fields from the stream into a buffer |
| 279 | * and makes the fields available by name. |
| 280 | * |
| 281 | * @exception java.lang.ClassNotFoundException if the class of a serialized |
| 282 | * object could not be found. |
| 283 | * @exception IOException if an I/O error occurs. |
| 284 | * @exception NotActiveException if readObject() is not currently active. |
| 285 | */ |
| 286 | abstract public ObjectInputStream.GetField readFields() |
| 287 | throws IOException, ClassNotFoundException, NotActiveException; |
| 288 | |
| 289 | abstract protected boolean enableResolveObject(boolean enable) throws SecurityException; |
| 290 | |
| 291 | abstract public void registerValidation(ObjectInputValidation obj, |
| 292 | int prio) |
| 293 | throws NotActiveException, InvalidObjectException; |
| 294 | |
| 295 | |
| 296 | /****************************************************************/ |
| 297 | |
| 298 | /* Use DataInput methods to read primitive data from the stream. */ |
| 299 | |
| 300 | abstract public int read() throws IOException; |
| 301 | abstract public int read(byte[] data, int offset, int length) |
| 302 | throws IOException; |
| 303 | abstract public boolean readBoolean() throws IOException; |
| 304 | abstract public byte readByte() throws IOException; |
| 305 | abstract public int readUnsignedByte() throws IOException; |
| 306 | abstract public short readShort() throws IOException; |
| 307 | abstract public int readUnsignedShort() throws IOException; |
| 308 | abstract public char readChar() throws IOException; |
| 309 | abstract public int readInt() throws IOException; |
| 310 | abstract public long readLong() throws IOException; |
| 311 | abstract public float readFloat() throws IOException; |
| 312 | abstract public double readDouble() throws IOException; |
| 313 | abstract public void readFully(byte[] data) throws IOException; |
| 314 | abstract public void readFully(byte[] data, int offset, int size) throws IOException; |
| 315 | abstract public String readUTF() throws IOException; |
| 316 | abstract public int available() throws IOException; |
| 317 | abstract public int skipBytes(int len) throws IOException; |
| 318 | |
| 319 | /* @deprecated */ |
| 320 | abstract public String readLine() throws IOException; |
| 321 | }; |