8210721: Replace legacy serial exception field with Throwable::cause

Reviewed-by: dfuchs, lancea

src/java.base/share/classes/java/lang/ClassNotFoundException.java

@@ -25,6 +25,11 @@
 
 package java.lang;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.ObjectStreamField;
+
 /**
  * Thrown when an application tries to load in a class through its
  * string name using:
@@ -56,15 +61,6 @@ public class ClassNotFoundException extends ReflectiveOperationException {
      */
      private static final long serialVersionUID = 9176873029745254542L;
 
-    /**
-     * This field holds the exception ex if the
-     * ClassNotFoundException(String s, Throwable ex) constructor was
-     * used to instantiate the object
-     * @serial
-     * @since 1.2
-     */
-    private Throwable ex;
-
     /**
      * Constructs a <code>ClassNotFoundException</code> with no detail message.
      */
@@ -92,8 +88,7 @@ public ClassNotFoundException(String s) {
      * @since 1.2
      */
     public ClassNotFoundException(String s, Throwable ex) {
-        super(s, null);  //  Disallow initCause
-        this.ex = ex;
+        super(s, ex);  //  Disallow initCause
     }
 
     /**
@@ -108,18 +103,42 @@ public ClassNotFoundException(String s, Throwable ex) {
      * @since 1.2
      */
     public Throwable getException() {
-        return ex;
+        return super.getCause();
     }
 
     /**
-     * Returns the cause of this exception (the exception that was raised
-     * if an error occurred while attempting to load the class; otherwise
-     * {@code null}).
+     * Serializable fields for ClassNotFoundException.
      *
-     * @return  the cause of this exception.
-     * @since   1.4
+     * @serialField ex Throwable
+     */
+    private static final ObjectStreamField[] serialPersistentFields = {
+        new ObjectStreamField("ex", Throwable.class)
+    };
+
+    /*
+     * Reconstitutes the ClassNotFoundException instance from a stream
+     * and initialize the cause properly when deserializing from an older
+     * version.
+     *
+     * The getException and getCause method returns the private "ex" field
+     * in the older implementation and ClassNotFoundException::cause
+     * was set to null.
+     */
+    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
+        ObjectInputStream.GetField fields = s.readFields();
+        Throwable exception = (Throwable) fields.get("ex", null);
+        if (exception != null) {
+            setCause(exception);
+        }
+    }
+
+    /*
+     * To maintain compatibility with older implementation, write a serial
+     * "ex" field with the cause as the value.
      */
-    public Throwable getCause() {
-        return ex;
+    private void writeObject(ObjectOutputStream out) throws IOException {
+        ObjectOutputStream.PutField fields = out.putFields();
+        fields.put("ex", super.getCause());
+        out.writeFields();
     }
 }

src/java.base/share/classes/java/lang/ExceptionInInitializerError.java

@@ -25,6 +25,11 @@
 
 package java.lang;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.ObjectStreamField;
+
 /**
  * Signals that an unexpected exception has occurred in a static initializer.
  * An <code>ExceptionInInitializerError</code> is thrown to indicate that an
@@ -47,24 +52,14 @@ public class ExceptionInInitializerError extends LinkageError {
      */
     private static final long serialVersionUID = 1521711792217232256L;
 
-    /**
-     * This field holds the exception if the
-     * ExceptionInInitializerError(Throwable thrown) constructor was
-     * used to instantiate the object
-     *
-     * @serial
-     *
-     */
-    private Throwable exception;
-
     /**
      * Constructs an <code>ExceptionInInitializerError</code> with
      * <code>null</code> as its detail message string and with no saved
      * throwable object.
      * A detail message is a String that describes this particular exception.
      */
     public ExceptionInInitializerError() {
-        initCause(null);  // Disallow subsequent initCause
+        initCause(null); // Disallow subsequent initCause
     }
 
     /**
@@ -76,23 +71,20 @@ public ExceptionInInitializerError() {
      * @param thrown The exception thrown
      */
     public ExceptionInInitializerError(Throwable thrown) {
-        initCause(null);  // Disallow subsequent initCause
-        this.exception = thrown;
+        super(null, thrown); // Disallow subsequent initCause
     }
 
     /**
-     * Constructs an ExceptionInInitializerError with the specified detail
+     * Constructs an {@code ExceptionInInitializerError} with the specified detail
      * message string.  A detail message is a String that describes this
      * particular exception. The detail message string is saved for later
      * retrieval by the {@link Throwable#getMessage()} method. There is no
      * saved throwable object.
      *
-     *
      * @param s the detail message
      */
     public ExceptionInInitializerError(String s) {
-        super(s);
-        initCause(null);  // Disallow subsequent initCause
+        super(s, null);  // Disallow subsequent initCause
     }
 
     /**
@@ -109,18 +101,43 @@ public ExceptionInInitializerError(String s) {
      *         throwable object.
      */
     public Throwable getException() {
-        return exception;
+        return super.getCause();
     }
 
     /**
-     * Returns the cause of this error (the exception that occurred
-     * during a static initialization that caused this error to be created).
+     * Serializable fields for ExceptionInInitializerError.
      *
-     * @return  the cause of this error or <code>null</code> if the
-     *          cause is nonexistent or unknown.
-     * @since   1.4
+     * @serialField exception Throwable
      */
-    public Throwable getCause() {
-        return exception;
+    private static final ObjectStreamField[] serialPersistentFields = {
+        new ObjectStreamField("exception", Throwable.class)
+    };
+
+    /*
+     * Reconstitutes the ExceptionInInitializerError instance from a stream
+     * and initialize the cause properly when deserializing from an older
+     * version.
+     *
+     * The getException and getCause method returns the private "exception"
+     * field in the older implementation and ExceptionInInitializerError::cause
+     * was set to null.
+     */
+    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
+        ObjectInputStream.GetField fields = s.readFields();
+        Throwable exception = (Throwable) fields.get("exception", null);
+        if (exception != null) {
+            setCause(exception);
+        }
     }
+
+    /*
+     * To maintain compatibility with older implementation, write a serial
+     * "exception" field with the cause as the value.
+     */
+    private void writeObject(ObjectOutputStream out) throws IOException {
+        ObjectOutputStream.PutField fields = out.putFields();
+        fields.put("exception", super.getCause());
+        out.writeFields();
+    }
+
 }

src/java.base/share/classes/java/lang/System.java

@@ -2201,6 +2201,9 @@ public byte[] getBytesUTF8NoRepl(String s) {
                 return StringCoding.getBytesUTF8NoRepl(s);
             }
 
+            public void setCause(Throwable t, Throwable cause) {
+                t.setCause(cause);
+            }
         });
     }
 }

src/java.base/share/classes/java/lang/Throwable.java

@@ -466,6 +466,16 @@ public synchronized Throwable initCause(Throwable cause) {
         return this;
     }
 
+    /*
+     * This is called by readObject of a few exceptions such as
+     * ClassNotFoundException and ExceptionInInitializerError to deserialize
+     * a stream output from an older runtime version where the cause may
+     * have set to null.
+     */
+    final void setCause(Throwable t) {
+        this.cause = t;
+    }
+
     /**
      * Returns a short description of this throwable.
      * The result is the concatenation of:

src/java.base/share/classes/java/lang/reflect/InvocationTargetException.java

@@ -25,6 +25,12 @@
 
 package java.lang.reflect;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.ObjectStreamField;
+import jdk.internal.misc.SharedSecrets;
+
 /**
  * InvocationTargetException is a checked exception that wraps
  * an exception thrown by an invoked method or constructor.
@@ -46,16 +52,6 @@ public class InvocationTargetException extends ReflectiveOperationException {
      */
     private static final long serialVersionUID = 4085088731926701167L;
 
-     /**
-     * This field holds the target if the
-     * InvocationTargetException(Throwable target) constructor was
-     * used to instantiate the object
-     *
-     * @serial
-     *
-     */
-    private Throwable target;
-
     /**
      * Constructs an {@code InvocationTargetException} with
      * {@code null} as the target exception.
@@ -70,8 +66,7 @@ protected InvocationTargetException() {
      * @param target the target exception
      */
     public InvocationTargetException(Throwable target) {
-        super((Throwable)null);  // Disallow initCause
-        this.target = target;
+        super(null, target);  // Disallow initCause
     }
 
     /**
@@ -82,8 +77,7 @@ public InvocationTargetException(Throwable target) {
      * @param s      the detail message
      */
     public InvocationTargetException(Throwable target, String s) {
-        super(s, null);  // Disallow initCause
-        this.target = target;
+        super(s, target);  // Disallow initCause
     }
 
     /**
@@ -96,17 +90,42 @@ public InvocationTargetException(Throwable target, String s) {
      * @return the thrown target exception (cause of this exception).
      */
     public Throwable getTargetException() {
-        return target;
+        return super.getCause();
     }
 
     /**
-     * Returns the cause of this exception (the thrown target exception,
-     * which may be {@code null}).
+     * Serializable fields for UndeclaredThrowableException.
      *
-     * @return  the cause of this exception.
-     * @since   1.4
+     * @serialField target Throwable
+     */
+    private static final ObjectStreamField[] serialPersistentFields = {
+        new ObjectStreamField("target", Throwable.class)
+    };
+
+    /*
+     * Reconstitutes the InvocationTargetException instance from a stream
+     * and initialize the cause properly when deserializing from an older
+     * version.
+     *
+     * The getException and getCause method returns the private "target" field
+     * in the older implementation and InvocationTargetException::cause
+     * was set to null.
+     */
+    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
+        ObjectInputStream.GetField fields = s.readFields();
+        Throwable exception = (Throwable) fields.get("target", null);
+        if (exception != null) {
+            SharedSecrets.getJavaLangAccess().setCause(this, exception);
+        }
+    }
+
+    /*
+     * To maintain compatibility with older implementation, write a serial
+     * "target" field with the cause as the value.
      */
-    public Throwable getCause() {
-        return target;
+    private void writeObject(ObjectOutputStream out) throws IOException {
+        ObjectOutputStream.PutField fields = out.putFields();
+        fields.put("target", super.getCause());
+        out.writeFields();
     }
 }