8297298: SequenceInputStream should override transferTo

Reviewed-by: bpb

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

@@ -235,4 +235,19 @@ public void close() throws IOException {
             throw ioe;
         }
     }
+
+    @Override
+    public long transferTo(OutputStream out) throws IOException {
+        Objects.requireNonNull(out, "out");
+        if (getClass() == SequenceInputStream.class) {
+            long c = 0;
+            while (in != null) {
+                c += in.transferTo(out);
+                nextStream();
+            }
+            return c;
+        } else {
+            return super.transferTo(out);
+        }
+    }
 }

test/jdk/java/io/SequenceInputStream/TransferTo.java

@@ -0,0 +1,206 @@
+/*
+ * Copyright (c) 2022, 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.
+ */
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.SequenceInputStream;
+import java.util.Arrays;
+import java.util.Random;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+import org.testng.annotations.Test;
+
+import jdk.test.lib.RandomFactory;
+
+import static java.lang.String.format;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertThrows;
+import static org.testng.Assert.assertTrue;
+
+/*
+ * @test
+ * @library /test/lib
+ * @build jdk.test.lib.RandomFactory
+ * @run testng/othervm/timeout=180 TransferTo
+ * @bug 8297298
+ * @summary Tests whether java.io.SequenceInputStream.transferTo conforms to the
+ *          InputStream.transferTo specification
+ * @key randomness
+ */
+public class TransferTo {
+    private static final int MIN_SIZE      = 10_000;
+    private static final int MAX_SIZE_INCR = 100_000_000 - MIN_SIZE;
+
+    private static final int ITERATIONS = 10;
+
+    private static final Random RND = RandomFactory.getRandom();
+
+    /*
+     * Testing API compliance: input stream must throw NullPointerException
+     * when parameter "out" is null.
+     */
+    @Test
+    public void testNullPointerException() throws Exception {
+        // factory for incoming data provider
+        InputStreamProvider inputStreamProvider = byteArrayInput();
+
+        // tests empty input stream
+        assertThrows(NullPointerException.class,
+                () -> inputStreamProvider.input().transferTo(null));
+
+        // tests single-byte input stream
+        assertThrows(NullPointerException.class,
+                () -> inputStreamProvider.input((byte) 1).transferTo(null));
+
+        // tests dual-byte input stream
+        assertThrows(NullPointerException.class,
+                () -> inputStreamProvider.input((byte) 1, (byte) 2).transferTo(null));
+    }
+
+    /*
+     * Testing API compliance: complete content of input stream must be
+     * transferred to output stream.
+     */
+    @Test
+    public void testStreamContents() throws Exception {
+        // factory for incoming data provider
+        InputStreamProvider inputStreamProvider = byteArrayInput();
+
+        // factory for outgoing data recorder
+        OutputStreamProvider outputStreamProvider = byteArrayOutput();
+
+        // tests empty input stream
+        checkTransferredContents(inputStreamProvider,
+                outputStreamProvider, new byte[0]);
+
+        // tests input stream with a length between 1k and 4k
+        checkTransferredContents(inputStreamProvider,
+                outputStreamProvider, createRandomBytes(1024, 4096));
+
+        // tests input stream with several data chunks, as 16k is more than a
+        // single chunk can hold
+        checkTransferredContents(inputStreamProvider,
+                outputStreamProvider, createRandomBytes(16384, 16384));
+
+        // tests randomly chosen starting positions within source and
+        // target stream
+        for (int i = 0; i < ITERATIONS; i++) {
+            byte[] inBytes = createRandomBytes(MIN_SIZE, MAX_SIZE_INCR);
+            int posIn = RND.nextInt(inBytes.length);
+            int posOut = RND.nextInt(MIN_SIZE);
+            checkTransferredContents(inputStreamProvider,
+                    outputStreamProvider, inBytes, posIn, posOut);
+        }
+
+        // tests reading beyond source EOF (must not transfer any bytes)
+        checkTransferredContents(inputStreamProvider,
+                outputStreamProvider, createRandomBytes(4096, 0), 4096, 0);
+
+        // tests writing beyond target EOF (must extend output stream)
+        checkTransferredContents(inputStreamProvider,
+                outputStreamProvider, createRandomBytes(4096, 0), 0, 4096);
+    }
+
+    /*
+     * Asserts that the transferred content is correct, i.e., compares the bytes
+     * actually transferred to those expected. The position of the input and
+     * output streams before the transfer are zero (BOF).
+     */
+    private static void checkTransferredContents(InputStreamProvider inputStreamProvider,
+            OutputStreamProvider outputStreamProvider, byte[] inBytes) throws Exception {
+        checkTransferredContents(inputStreamProvider,
+                outputStreamProvider, inBytes, 0, 0);
+    }
+
+    /*
+     * Asserts that the transferred content is correct, i. e. compares the bytes
+     * actually transferred to those expected. The positions of the input and
+     * output streams before the transfer are provided by the caller.
+     */
+    private static void checkTransferredContents(InputStreamProvider inputStreamProvider,
+            OutputStreamProvider outputStreamProvider, byte[] inBytes, int posIn,
+            int posOut) throws Exception {
+        AtomicReference<Supplier<byte[]>> recorder = new AtomicReference<>();
+        try (InputStream in = inputStreamProvider.input(inBytes);
+            OutputStream out = outputStreamProvider.output(recorder::set)) {
+            // skip bytes until starting position
+            in.skipNBytes(posIn);
+            out.write(new byte[posOut]);
+
+            long reported = in.transferTo(out);
+            int count = inBytes.length - posIn;
+
+            assertEquals(reported, count,
+                    format("reported %d bytes but should report %d", reported, count));
+
+            byte[] outBytes = recorder.get().get();
+            assertTrue(Arrays.equals(inBytes, posIn, posIn + count,
+                    outBytes, posOut, posOut + count),
+                    format("inBytes.length=%d, outBytes.length=%d", count, outBytes.length));
+        }
+    }
+
+    /*
+     * Creates an array of random size (between min and min + maxRandomAdditive)
+     * filled with random bytes
+     */
+    private static byte[] createRandomBytes(int min, int maxRandomAdditive) {
+        byte[] bytes = new byte[min +
+                                (maxRandomAdditive == 0 ? 0 : RND.nextInt(maxRandomAdditive))];
+        RND.nextBytes(bytes);
+        return bytes;
+    }
+
+    private interface InputStreamProvider {
+        InputStream input(byte... bytes) throws Exception;
+    }
+
+    private interface OutputStreamProvider {
+        OutputStream output(Consumer<Supplier<byte[]>> spy) throws Exception;
+    }
+
+    private static InputStreamProvider byteArrayInput() {
+        return bytes -> {
+            InputStream is1 = new ByteArrayInputStream(bytes, 0, bytes.length / 2);
+            InputStream is2 = new ByteArrayInputStream(bytes, bytes.length / 2, bytes.length);
+            return new SequenceInputStream(is1, is2);
+        };
+    }
+
+    private static OutputStreamProvider byteArrayOutput() {
+        return new OutputStreamProvider() {
+            @Override
+            public OutputStream output(Consumer<Supplier<byte[]>> spy) {
+                ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+                spy.accept(outputStream::toByteArray);
+                return outputStream;
+            }
+        };
+    }
+
+}