/*
* Copyright 2007-2009 Sun Microsystems, Inc.
*
* This file is part of Project Darkstar Server.
*
* Project Darkstar Server is free software: you can redistribute it
* and/or modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation and
* distributed hereunder to you.
*
* Project Darkstar Server 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.sun.sgs.impl.service.data;
import com.sun.sgs.app.ManagedObject;
import com.sun.sgs.app.ManagedReference;
import com.sun.sgs.app.ObjectIOException;
import com.sun.sgs.app.TransactionNotActiveException;
import com.sun.sgs.impl.sharedutil.LoggerWrapper;
import com.sun.sgs.impl.sharedutil.Objects;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import java.io.OutputStream;
import java.io.Serializable;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.IdentityHashMap;
import java.util.Stack;
import java.util.logging.Level;
import java.util.logging.Logger;
/** Defines serialization utilities. This class cannot be instantiated. */
final class SerialUtil {
/**
* The first 4 bytes of output streams created by serialization protocol
* version 2.
*/
private static final byte[] SERIAL_PROTOCOL_2_HEADER = {
(byte) 0xac, (byte) 0xed, 0x00, 0x05
};
/**
* The initial byte to use in place of the initial 4 bytes of serial output
* using serialization protocol version 2.
*/
private static final byte SERIAL_PROTOCOL_2 = 1;
/**
* The initial byte to use for serial output other than serialization
* protocol version 2.
*/
private static final byte SERIAL_PROTOCOL_OTHER = 2;
/** The logger for this class. */
private static final LoggerWrapper logger =
new LoggerWrapper(Logger.getLogger(SerialUtil.class.getName()));
/** This class cannot be instantiated. */
private SerialUtil() {
throw new AssertionError();
}
/**
* Converts serialized data into an object.
*
* @param data the serialized data
* @param classSerial controls reading of class descriptors
* @return the object
* @throws ObjectIOException if a problem occurs deserializing the object
*/
static Object deserialize(byte[] data, ClassSerialization classSerial) {
ObjectInputStream in = null;
try {
in = new CustomClassDescriptorObjectInputStream(
new CompressByteArrayInputStream(data), classSerial);
return in.readObject();
} catch (ClassNotFoundException e) {
throw new ObjectIOException(
"Class not found while deserializing object: " +
e.getMessage(),
e, false);
} catch (IOException e) {
throw new ObjectIOException(
"Problem deserializing object: " + e.getMessage(), e, false);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
}
}
}
}
/**
* Defines an ObjectInputStream whose reading of class descriptors is
* customized by an instance of ClassSerialization.
*/
private static final class CustomClassDescriptorObjectInputStream
extends ObjectInputStream
{
private final ClassSerialization classSerial;
CustomClassDescriptorObjectInputStream(InputStream in,
ClassSerialization classSerial)
throws IOException
{
super(in);
this.classSerial = classSerial;
}
protected ObjectStreamClass readClassDescriptor()
throws ClassNotFoundException, IOException
{
return classSerial.readClassDescriptor(this);
}
}
/**
* Defines an input stream that obtains its data from a byte array, like
* ByteArrayInputStream, and decompresses the start of the stream based on
* its first byte. Assumes that the first byte will either be
* SERIAL_PROTOCOL_2 or SERIAL_PROTOCOL_OTHER. If the value is
* SERIAL_PROTOCOL_2, then that byte is replaced with
* SERIAL_PROTOCOL_2_HEADER. If it is SERIAL_PROTOCOL_OTHER, then the real
* header is expected to follow.
*/
private static final class CompressByteArrayInputStream
extends ByteArrayInputStream
{
CompressByteArrayInputStream(byte[] bytes) throws IOException {
super(getBytes(bytes));
}
private static byte[] getBytes(byte[] bytes) throws IOException {
int b = (bytes.length > 0) ? bytes[0] : -1;
if (b == SERIAL_PROTOCOL_2) {
byte[] result = new byte[bytes.length + 3];
System.arraycopy(SERIAL_PROTOCOL_2_HEADER, 0, result, 0, 4);
System.arraycopy(bytes, 1, result, 4, bytes.length - 1);
return result;
} else if (b == SERIAL_PROTOCOL_OTHER) {
byte[] result = new byte[bytes.length - 1];
System.arraycopy(bytes, 1, result, 0, bytes.length - 1);
return result;
} else {
throw new IOException("Unexpected initial byte: " + b);
}
}
}
/**
* Converts an managed object into serialized data.
*
* @param object the object
* @param classSerial controls writing of class descriptors
* @return the serialized data
* @throws ObjectIOException if a problem occurs serializing the object
* and, in particular, if a <code>ManagedObject</code> is
* referenced without an intervening <code>ManagedReference</code>
*/
static byte[] serialize(ManagedObject object,
ClassSerialization classSerial)
{
ObjectOutputStream out = null;
try {
ByteArrayOutputStream baos = new CompressByteArrayOutputStream();
out = new CheckReferencesObjectOutputStream(
baos, object, classSerial);
out.writeObject(object);
out.flush();
return baos.toByteArray();
} catch (ObjectIOException e) {
check(object, e);
throw e;
} catch (TransactionNotActiveException e) {
throw new TransactionNotActiveException(
"Attempt to perform an operation during serialization that " +
"requires a active transaction: " + e.getMessage(),
e);
} catch (IOException e) {
throw new ObjectIOException(
"Problem serializing object: " + e.getMessage(), e, false);
} finally {
if (out != null) {
try {
out.close();
} catch (IOException e) {
}
}
}
}
/**
* Defines a ByteArrayOutputStream that compresses the first 4 bytes if
* they match the standard values for a serialization stream. If those
* bytes match SERIAL_PROTOCOL_2_HEADER, replaces them with
* SERIAL_PROTOCOL_2. Otherwise, prepends SERIAL_PROTOCOL_OTHER.
*/
private static final class CompressByteArrayOutputStream
extends ByteArrayOutputStream
{
CompressByteArrayOutputStream() { }
public byte[] toByteArray() {
byte[] newbuf;
if (startsWith(SERIAL_PROTOCOL_2_HEADER)) {
newbuf = new byte[count - 3];
newbuf[0] = SERIAL_PROTOCOL_2;
System.arraycopy(buf, 4, newbuf, 1, count - 4);
} else {
newbuf = new byte[count + 1];
newbuf[0] = SERIAL_PROTOCOL_OTHER;
System.arraycopy(buf, 0, newbuf, 1, count);
}
return newbuf;
}
private boolean startsWith(byte[] prefix) {
if (count < prefix.length) {
return false;
}
for (int i = 0; i < prefix.length; i++) {
if (buf[i] != prefix[i]) {
return false;
}
}
return true;
}
}
/**
* Defines an ObjectOutputStream whose writing of class descriptors can be
* customized.
*/
private static class CustomClassDescriptorObjectOutputStream
extends ObjectOutputStream
{
final ClassSerialization classSerial;
CustomClassDescriptorObjectOutputStream(OutputStream out,
ClassSerialization classSerial)
throws IOException
{
super(out);
this.classSerial = classSerial;
}
protected void writeClassDescriptor(ObjectStreamClass desc)
throws IOException
{
classSerial.writeClassDescriptor(desc, this);
}
}
/**
* Define an ObjectOutputStream that checks for references to
* ManagedObjects not made through ManagedReferences. Note that this
* stream will not be able to detect direct references to the top level
* object, except when the reference is the synthetic reference made by an
* inner class instance.
*/
private static final class CheckReferencesObjectOutputStream
extends CustomClassDescriptorObjectOutputStream
{
/** The top level managed object being serialized. */
private final ManagedObject topLevelObject;
/**
* Creates an instance that writes to a stream for a managed object
* being serialized.
*/
CheckReferencesObjectOutputStream(OutputStream out,
ManagedObject topLevelObject,
ClassSerialization classSerial)
throws IOException
{
super(out, classSerial);
this.topLevelObject = topLevelObject;
AccessController.doPrivileged(
new PrivilegedAction<Void>() {
public Void run() {
enableReplaceObject(true);
return null;
}
});
}
/** Check for references to managed objects. */
protected Object replaceObject(Object object) throws IOException {
if (object == null) {
return null;
}
Class<?> cl = object.getClass();
if (object != topLevelObject && object instanceof ManagedObject) {
throw new ObjectIOException(
"ManagedObject was not referenced through a " +
"ManagedReference: " + Objects.safeToString(object),
false);
} else if (object instanceof Serializable) {
classSerial.checkInstantiable(ObjectStreamClass.lookup(cl));
}
if (cl.isAnonymousClass()) {
if (logger.isLoggable(Level.FINE)) {
logger.log(
Level.FINE,
"Storing an instance of an anonymous class: " +
"{0}, {1}",
Objects.safeToString(object), cl);
}
} else if (cl.isLocalClass()) {
if (logger.isLoggable(Level.FINE)) {
logger.log(
Level.FINE,
"Storing an instance of a local class: {0}, {1}",
Objects.safeToString(object), cl);
}
}
return object;
}
}
/**
* Checks an object for direct references to managed objects, throwing an
* exception that contains debugging information about where the bad
* reference was found.
*
* @param object the object to check
* @param cause the exception that prompted the check, or null
* @throws ObjectIOException if a direct reference to a managed object is
* found
*/
static void check(Object object, ObjectIOException cause) {
try {
new Check(object, cause).checkObject(object);
} catch (ObjectIOException e) {
/* Don't include the nested stack trace from the check itself */
e.fillInStackTrace();
throw e;
}
}
/**
* Class to check for bad references. Uses reflection to traverse the
* object graph, keeping a stack describing the traversal for use in error
* messages. Although the check performed does not account for
* serialization features such as writeReplace, the assumption is that
* direct references to managed objects are wrong wherever they are found.
*/
private static class Check {
/** The top level object being checked. */
private final Object topObject;
/** The thrown exception that prompted the check, or null. */
private final ObjectIOException cause;
/** The stack that stores information about object references. */
private final DebugStack stack = new DebugStack();
/** Stores information about objects already seen. */
private final IdentityHashMap<Object, Boolean> seen =
new IdentityHashMap<Object, Boolean>();
/** A version of Stack that formats output appropriately. */
private static class DebugStack extends Stack<String> {
/* Silence lint warning */
private static final long serialVersionUID = 1;
DebugStack() { }
public String push(String s) {
return super.push((isEmpty() ? "\t-root: " : "\t-") + s);
}
public String toString() {
StringBuilder buffer = new StringBuilder();
if (!isEmpty()) {
while (true) {
buffer.append(pop());
if (isEmpty()) {
break;
}
buffer.append('\n');
}
}
return buffer.toString();
}
}
/**
* Creates an instance for the specified top level object and cause.
*/
Check(Object topObject, ObjectIOException cause) {
this.topObject = topObject;
this.cause = cause;
}
/** Checks an object for bad references. */
void checkObject(Object object) {
if (object != null &&
!(object instanceof ManagedReference) &&
!seen.containsKey(object))
{
Class<?> cl = object.getClass();
if (object != topObject && object instanceof ManagedObject) {
stack.push("object (class \"" + cl.getName() + "\", " +
Objects.safeToString(object) + ")");
throw new ObjectIOException(
"ManagedObject was not referenced through a " +
"ManagedReference:\n" + stack,
cause, false);
}
seen.put(object, Boolean.TRUE);
if (cl.isArray()) {
checkArray(object);
} else {
checkNonArray(object);
}
}
}
/** Checks an array for bad reference. */
private void checkArray(Object array) {
Class<?> cl = array.getClass();
Class<?> compCl = cl.getComponentType();
if (!compCl.isPrimitive()) {
int len = Array.getLength(array);
stack.push("array (class \"" + className(cl) +
"\", size: " + len + ")");
for (int i = 0; i < len; i++) {
stack.push("element of array (index: " + i + ")");
checkObject(Array.get(array, i));
stack.pop();
}
stack.pop();
}
}
/** Checks an non-array for bad reference. */
private void checkNonArray(Object object) {
Class<?> cl = object.getClass();
stack.push("object (class \"" + cl.getName() + "\", " +
Objects.safeToString(object) + ")");
/*
* According to the JLS 3.0, all local classes are considered to be
* inner classes, even if they appear in a static context. Testing
* shows, though, that instances of local classes created in a
* static context do not contain a pointer to the enclosing class.
* For that reason, there is no good way to distinguish which local
* classes could cause a non-managed reference to the enclosing
* class, so don't check that case here. -tjb@sun.com (03/30/2009)
*/
if (!cl.isLocalClass() && !Modifier.isStatic(cl.getModifiers())) {
Class<?> enclosingClass = cl.getEnclosingClass();
if (enclosingClass != null &&
ManagedObject.class.isAssignableFrom(enclosingClass))
{
throw new ObjectIOException(
"ManagedObject of type " + enclosingClass.getName() +
" was not referenced through a ManagedReference" +
" because of a reference from an inner class:\n" +
stack,
cause, false);
}
}
for ( ; cl != null; cl = cl.getSuperclass()) {
for (Field f : cl.getDeclaredFields()) {
if (!Modifier.isStatic(f.getModifiers()) &&
!f.getType().isPrimitive())
{
stack.push((f.isSynthetic() ? "synthetic " : "") +
"field (class \"" + cl.getName() +
"\", name: \"" + f.getName() +
"\", type: \"" + className(f.getType()) +
"\")");
f.setAccessible(true);
try {
checkObject(f.get(object));
} catch (IllegalAccessException e) {
throw new AssertionError(e);
}
stack.pop();
}
}
}
stack.pop();
}
/** Returns the name of a class, converting array class names. */
private static String className(Class<?> cl) {
StringBuilder sb = new StringBuilder();
while (cl.isArray()) {
sb.append("[]");
cl = cl.getComponentType();
}
String className = cl.getName();
sb.insert(0, className);
return sb.toString();
}
}
}