--- /dev/null 2020-01-15 12:45:36.000000000 +0000 +++ new/test/jdk/java/nio/channels/DatagramChannel/Truncate.java 2020-01-15 12:45:35.000000000 +0000 @@ -0,0 +1,140 @@ +/* + * 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 8053479 + * @run main Truncate + * @summary Test DatagramChannel receive/read where there are fewer bytes remaining + * in the buffer than are required to hold the datagram. The remainder of the + * datagram should be silently discarded. + */ + +import java.io.IOException; +import java.net.InetAddress; +import java.net.InetSocketAddress; +import java.net.SocketAddress; +import java.nio.ByteBuffer; +import java.nio.channels.DatagramChannel; +import java.util.Arrays; +import java.util.stream.IntStream; + +public class Truncate { + static final int LARGE_SIZE = 1000; + static final int SMALL_SIZE = 100; + + public static void main(String[] args) throws Exception { + try (DatagramChannel dc = DatagramChannel.open()) { + dc.bind(new InetSocketAddress(InetAddress.getLoopbackAddress(), 0)); + + // not connected + testReceiveDiscards(dc); + + // connected + dc.connect(dc.getLocalAddress()); + testReceiveDiscards(dc); + testReadDiscards(dc); + testScatteringReadDiscards(dc); + } + } + + /** + * Receive a datagram with a buffer that has fewer bytes remaining than are + * required to hold the datagram. + */ + static void testReceiveDiscards(DatagramChannel dc) throws IOException { + ByteBuffer largeBuffer = send(dc, LARGE_SIZE, dc.getLocalAddress()); + + ByteBuffer smallBuffer = ByteBuffer.allocate(SMALL_SIZE); + SocketAddress sender = dc.receive(smallBuffer); + assertTrue(sender.equals(dc.getLocalAddress())); + + // check buffer/contents + smallBuffer.flip(); + assertTrue(smallBuffer.remaining() == SMALL_SIZE); + assertTrue(Arrays.equals(smallBuffer.array(), 0, SMALL_SIZE, + largeBuffer.array(), 0, SMALL_SIZE)); + } + + /** + * Read a datagram with a buffer that has fewer bytes remaining than are + * required to hold the datagram. + */ + static void testReadDiscards(DatagramChannel dc) throws IOException { + ByteBuffer largeBuffer = send(dc, LARGE_SIZE, dc.getRemoteAddress()); + + ByteBuffer smallBuffer = ByteBuffer.allocate(SMALL_SIZE); + int n = dc.read(smallBuffer); + assertTrue(n == SMALL_SIZE); + + // check buffer/contents + smallBuffer.flip(); + assertTrue(smallBuffer.remaining() == SMALL_SIZE); + assertTrue(Arrays.equals(smallBuffer.array(), 0, SMALL_SIZE, + largeBuffer.array(), 0, SMALL_SIZE)); + } + + /** + * Read a datagram with an array of buffers that have fewer bytes remaining + * than are required to hold the datagram. + */ + static void testScatteringReadDiscards(DatagramChannel dc) throws IOException { + ByteBuffer largeBuffer = send(dc, LARGE_SIZE, dc.getRemoteAddress()); + + ByteBuffer smallBuffer1 = ByteBuffer.allocate(SMALL_SIZE); + ByteBuffer smallBuffer2 = ByteBuffer.allocate(SMALL_SIZE); + ByteBuffer[] bufs = new ByteBuffer[] { smallBuffer1, smallBuffer2 }; + long n = dc.read(bufs); + assertTrue(n == (SMALL_SIZE * bufs.length)); + + // check buffer/contents + smallBuffer1.flip(); + assertTrue(smallBuffer1.remaining() == SMALL_SIZE); + assertTrue(Arrays.equals(smallBuffer1.array(), 0, SMALL_SIZE, + largeBuffer.array(), 0, SMALL_SIZE)); + smallBuffer2.flip(); + assertTrue(smallBuffer2.remaining() == SMALL_SIZE); + assertTrue(Arrays.equals(smallBuffer2.array(), 0, SMALL_SIZE, + largeBuffer.array(), SMALL_SIZE, SMALL_SIZE << 1)); + } + + /** + * Send a datagram of the given size to the given target address. + * @return the buffer with the datagram sent to the target address + */ + static ByteBuffer send(DatagramChannel dc, int size, SocketAddress target) + throws IOException + { + ByteBuffer buffer = ByteBuffer.allocate(size); + IntStream.range(0, size).forEach(i -> buffer.put((byte)i)); + buffer.flip(); + + int n = dc.send(buffer, target); + assertTrue(n == size); + buffer.flip(); + return buffer; + } + + static void assertTrue(boolean e) { + if (!e) throw new RuntimeException(); + } +}