8238763: ObjectInputStream readUnshared method handling of Records

Reviewed-by: rriggs

src/java.base/share/classes/java/io/ObjectInputStream.java

@@ -2186,7 +2186,8 @@ public class ObjectInputStream
         if (isRecord) {
             assert obj == null;
             obj = readRecord(desc);
-            handles.setObject(passHandle, obj);
+            if (!unshared)
+                handles.setObject(passHandle, obj);
         } else if (desc.isExternalizable()) {
             readExternalData((Externalizable) obj, desc);
         } else {

test/jdk/java/io/Serializable/records/UnsharedTest.java

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2020, 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.
+ *
+ * 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.
+ */
+
+/*
+ * @test
+ * @bug 8238763
+ * @summary ObjectInputStream readUnshared method handling of Records
+ * @compile --enable-preview -source ${jdk.version} UnsharedTest.java
+ * @run testng/othervm --enable-preview UnsharedTest
+ */
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InvalidObjectException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import org.testng.annotations.Test;
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.expectThrows;
+
+/**
+ * Tests OOS::writeUnshared and OIS::readUnshared to verify that records
+ * are correctly unshared in the stream as appropriate.
+ */
+public class UnsharedTest {
+
+    record Foo(int x) implements Serializable { }
+
+    static final Class<InvalidObjectException> IOE = InvalidObjectException.class;
+
+    @Test
+    public void testReadUnshared() throws Exception {
+        var foo = new Foo(6);
+        {  // shared - sanity to ensure the second foo is a ref
+            var byteStream = serialize(foo, foo);
+            var foo1 = (Foo) deserializeOne(byteStream);
+            assertEquals(foo1.x, foo.x);
+            var foo2 = (Foo) deserializeOne(byteStream);
+            assertEquals(foo2.x, foo.x);
+            assertTrue(foo2 == foo1);
+        }
+        {  // unshared
+            var byteStream = serialize(foo, foo);
+            var foo1 = (Foo) deserializeOneUnshared(byteStream);
+            assertEquals(foo1.x, foo.x);
+            var expected = expectThrows(IOE, () -> deserializeOne(byteStream));
+            assertTrue(expected.getMessage().contains("cannot read back reference to unshared object"));
+        }
+    }
+
+    @Test
+    public void testWriteUnshared() throws Exception {
+        var foo = new Foo(7);
+        {  // shared - sanity to ensure the second foo is NOT a ref
+            var byteStream = serializeUnshared(foo, foo);
+            var foo1 = (Foo) deserializeOne(byteStream);
+            assertEquals(foo1.x, foo.x);
+            var foo2 = (Foo) deserializeOne(byteStream);
+            assertEquals(foo2.x, foo.x);
+            assertTrue(foo2 != foo1);
+        }
+        {  // unshared
+            var byteStream = serializeUnshared(foo, foo);
+            var foo1 = (Foo) deserializeOneUnshared(byteStream);
+            assertEquals(foo1.x, foo.x);
+            var foo2 = (Foo) deserializeOneUnshared(byteStream);
+            assertEquals(foo2.x, foo.x);
+            assertTrue(foo2 != foo1);
+        }
+    }
+
+    // ---
+
+    static ObjectInputStream serialize(Object... objs) throws IOException {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ObjectOutputStream oos = new ObjectOutputStream(baos);
+        for (Object obj : objs)
+            oos.writeObject(obj);
+        oos.close();
+        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+        return new ObjectInputStream(bais);
+    }
+
+    static ObjectInputStream serializeUnshared(Object... objs) throws IOException {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ObjectOutputStream oos = new ObjectOutputStream(baos);
+        for (Object obj : objs)
+            oos.writeUnshared(obj);
+        oos.close();
+        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+        return new ObjectInputStream(bais);
+    }
+
+    @SuppressWarnings("unchecked")
+    static Object deserializeOne(ObjectInputStream ois)
+        throws IOException, ClassNotFoundException
+    {
+        return ois.readObject();
+    }
+
+    @SuppressWarnings("unchecked")
+    static Object deserializeOneUnshared(ObjectInputStream ois)
+        throws IOException, ClassNotFoundException
+    {
+        return ois.readUnshared();
+    }
+}