8246729: MappedByteBuffer.force() throws IndexOutOfBoundsException

Reviewed-by: psandoz, alanb

src/java.base/share/classes/java/nio/MappedByteBuffer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -223,11 +223,9 @@ public final MappedByteBuffer force() {
         if (fd == null) {
             return this;
         }
-        if (isSync) {
-            return force(0, limit());
-        }
-        if ((address != 0) && (capacity() != 0)) {
-            return force(0, capacity());
+        int limit = limit();
+        if (isSync || ((address != 0) && (limit != 0))) {
+            return force(0, limit);
         }
         return this;
     }
@@ -278,9 +276,10 @@ public final MappedByteBuffer force(int index, int length) {
         if (fd == null) {
             return this;
         }
-        if ((address != 0) && (limit() != 0)) {
+        int limit = limit();
+        if ((address != 0) && (limit != 0)) {
             // check inputs
-            Objects.checkFromIndexSize(index, length, limit());
+            Objects.checkFromIndexSize(index, length, limit);
             MappedMemoryUtils.force(fd, address, isSync, index, length);
         }
         return this;

test/jdk/java/nio/MappedByteBuffer/Force.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 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
@@ -22,20 +22,31 @@
  */
 
 /* @test
- * @bug 4625907
+ * @bug 4625907 8246729
  * @summary Testing force()
+ * @library /test/lib
+ * @build jdk.test.lib.RandomFactory
  * @run main/othervm Force
  * @key randomness
  */
 
-import java.io.*;
-import java.nio.*;
-import java.util.*;
-import java.nio.channels.*;
+import java.io.File;
+import java.io.RandomAccessFile;
+import java.nio.MappedByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import static java.nio.file.StandardOpenOption.*;
+import java.util.Random;
+import jdk.test.lib.RandomFactory;
 
 public class Force {
     public static void main(String[] args) throws Exception {
-        Random random = new Random();
+        test1();
+        test2();
+    }
+
+    private static void test1() throws Exception {
+        Random random = RandomFactory.getRandom();
         long filesize = random.nextInt(3*1024*1024);
         int cut = random.nextInt((int)filesize);
         File file = File.createTempFile("Blah", null);
@@ -51,4 +62,14 @@ public static void main(String[] args) throws Exception {
         System.gc();
         Thread.sleep(500);
     }
+
+    private static void test2() throws Exception {
+        var path = Files.createTempFile("test", "map");
+        var channel = FileChannel.open(path, READ, WRITE);
+        MappedByteBuffer buffer =
+            channel.map(FileChannel.MapMode.READ_WRITE, 0, 1000);
+        buffer.putInt(1234);
+        buffer.limit(4);
+        buffer.force();
+    }
 }