8374382: (aio) AsynchronousFileChannel writes wrong content using heap ByteBuffer when position != 0

Reviewed-by: jpai

Author: Alan Bateman

src/java.base/windows/classes/sun/nio/ch/WindowsAsynchronousFileChannelImpl.java

@@ -452,7 +452,7 @@ public void run() {
                 address = IOUtil.bufferAddress(dst) + pos;
             } else {
                 buf = Util.getTemporaryDirectBuffer(rem);
-                address = IOUtil.bufferAddress(buf) + pos;
+                address = IOUtil.bufferAddress(buf);
             }
 
             boolean pending = false;
@@ -640,7 +640,7 @@ public void run() {
                 // temporarily restore position as we don't know how many bytes
                 // will be written
                 src.position(pos);
-                address = IOUtil.bufferAddress(buf) + pos;
+                address = IOUtil.bufferAddress(buf);
             }
 
             try {

test/jdk/java/nio/channels/AsynchronousFileChannel/BufferPositions.java

@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2025, 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 8374382
+ * @summary Test AsynchronousFileChannel.read/write with ByteBuffers and varied buffer positions
+ * @run junit/othervm BufferPositions
+ */
+
+import java.lang.foreign.Arena;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousFileChannel;
+import java.nio.channels.CompletionHandler;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.stream.Stream;
+import static java.nio.file.StandardOpenOption.*;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+import static org.junit.jupiter.api.Assertions.*;
+
+class BufferPositions {
+
+    private static final int BUF_SIZE = 32;
+
+    /**
+     * The buffers to test.
+     */
+    static Stream<ByteBuffer> buffers() {
+        List<ByteBuffer> buffers = List.of(
+                ByteBuffer.allocate(BUF_SIZE),
+                ByteBuffer.allocateDirect(BUF_SIZE),
+                ByteBuffer.wrap(new byte[BUF_SIZE]),
+                Arena.global().allocate(BUF_SIZE).asByteBuffer(),
+                Arena.ofAuto().allocate(BUF_SIZE).asByteBuffer(),
+                Arena.ofShared().allocate(BUF_SIZE).asByteBuffer()
+        );
+        Stream<ByteBuffer> slices = buffers.stream()
+                .map(bb -> bb.slice(1, bb.capacity() - 1));
+        return Stream.concat(buffers.stream(), slices);
+    }
+
+    /**
+     * Test using an AsynchronousFileChannel to read bytes into the given buffer.
+     */
+    @ParameterizedTest
+    @MethodSource("buffers")
+    void testRead(ByteBuffer bb) throws Exception {
+        Path file = Files.createTempFile(Path.of("."), "test", "dat");
+
+        // populate temp file
+        int size = bb.capacity();
+        byte[] contents = new byte[size];
+        for (int i = 0; i < size; i++) {
+            contents[i] = (byte)(i + 1);
+        }
+        Files.write(file, contents);
+
+        // read bytes using the buffer as the destination and all possible buffer positions
+        try (AsynchronousFileChannel ch = AsynchronousFileChannel.open(file, READ)) {
+            for (int filePosition = 0; filePosition < size; filePosition++) {
+                for (int bufPos = 0; bufPos < size; bufPos++) {
+                    // read one byte
+                    bb.position(bufPos);
+                    bb.limit(bufPos + 1);
+                    int n = read(ch, filePosition, bb);
+                    assertEquals(1, n);
+                    assertEquals(bufPos + 1, bb.position());
+                    assertEquals(contents[filePosition], bb.get(bufPos));
+                }
+            }
+        }
+    }
+
+    /**
+     * Test using an AsynchronousFileChannel to write bytes from the given buffer.
+     */
+    @ParameterizedTest
+    @MethodSource("buffers")
+    void testWrite(ByteBuffer bb) throws Exception {
+        Path file = Files.createTempFile(Path.of("."), "test", "dat");
+
+        // populate temp file, all zeros
+        int size = bb.capacity();
+        byte[] contents = new byte[size];
+        Files.write(file, contents);
+
+        // write bytes using the buffer as the source and all possible buffer positions
+        try (AsynchronousFileChannel ch = AsynchronousFileChannel.open(file, READ, WRITE)) {
+            for (int filePosition = 0; filePosition < size; filePosition++) {
+                for (int bufPos = 0; bufPos < size; bufPos++) {
+                    // write one byte
+                    byte b = (byte) ThreadLocalRandom.current().nextInt();
+                    bb.position(bufPos);
+                    bb.limit(bufPos + 1);
+                    bb.put(bufPos, b);
+                    int n = write(ch, filePosition, bb);
+                    assertEquals(1, n);
+                    assertEquals(bufPos + 1, bb.position());
+                    assertEquals(b, bb.get(bufPos));
+
+                    // check byte was written at the expected file position
+                    ByteBuffer dst = ByteBuffer.allocate(1);
+                    int nread = ch.read(dst, filePosition).get();
+                    assertEquals(1, nread);
+                    assertEquals(b, dst.get(0));
+                }
+            }
+        }
+    }
+
+    /**
+     * Reads a byte from a channel into the given buffer, at the given file position.
+     */
+    private int read(AsynchronousFileChannel ch, long position, ByteBuffer bb) throws Exception {
+        if (ThreadLocalRandom.current().nextBoolean()) {
+            return ch.read(bb, position).get();
+        } else {
+            var handler = new Handler<Integer>();
+            ch.read(bb, position, null, handler);
+            return handler.result();
+        }
+    }
+
+    /**
+     * Writes a byte to a channel from the given buffer, at the given file position.
+     */
+    private int write(AsynchronousFileChannel ch, long position, ByteBuffer bb) throws Exception {
+        if (ThreadLocalRandom.current().nextBoolean()) {
+            return ch.write(bb, position).get();
+        } else {
+            var handler = new Handler<Integer>();
+            ch.write(bb, position, null, handler);
+            return handler.result();
+        }
+    }
+
+    /**
+     * CompletionHandler that defines a method to await the result of an I/O operation.
+     */
+    private static class Handler<T> implements CompletionHandler<T, Void> {
+        T result;
+        Throwable ex;
+        final CountDownLatch done = new CountDownLatch(1);
+
+        @Override
+        public void completed(T result, Void att) {
+            this.result = result;
+            done.countDown();
+        }
+
+        @Override
+        public void failed(Throwable ex, Void att) {
+            this.ex = ex;
+            done.countDown();
+        }
+
+        T result() throws InterruptedException {
+            done.await();
+            assertNull(ex);
+            return result;
+        }
+    }
+}