8273038: ChannelInputStream.transferTo() uses FileChannel.transferTo(FileChannel)

Reviewed-by: alanb

src/java.base/share/classes/sun/nio/ch/ChannelOutputStream.java

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2021, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package sun.nio.ch;
+
+import java.io.*;
+import java.nio.*;
+import java.nio.channels.*;
+import java.nio.channels.spi.*;
+import java.util.Objects;
+
+/**
+ * This class is defined here rather than in java.nio.channels.Channels
+ * so that it will be accessible from java.nio.channels.Channels and
+ * sun.nio.ch.ChannelInputStream.
+ *
+ *
+ * @author Mark Reinhold
+ * @author Mike McCloskey
+ * @author JSR-51 Expert Group
+ * @since 18
+ */
+public class ChannelOutputStream extends OutputStream {
+
+    private final WritableByteChannel ch;
+    private ByteBuffer bb;
+    private byte[] bs;       // Invoker's previous array
+    private byte[] b1;
+
+    /**
+     * Write all remaining bytes in buffer to the given channel.
+     * If the channel is selectable then it must be configured blocking.
+     */
+    private static void writeFullyImpl(WritableByteChannel ch, ByteBuffer bb)
+        throws IOException
+    {
+        while (bb.remaining() > 0) {
+            int n = ch.write(bb);
+            if (n <= 0)
+                throw new RuntimeException("no bytes written");
+        }
+    }
+
+    /**
+     * Write all remaining bytes in buffer to the given channel.
+     *
+     * @throws  IllegalBlockingModeException
+     *          If the channel is selectable and configured non-blocking.
+     */
+    private static void writeFully(WritableByteChannel ch, ByteBuffer bb)
+        throws IOException
+    {
+        if (ch instanceof SelectableChannel sc) {
+            synchronized (sc.blockingLock()) {
+                if (!sc.isBlocking())
+                    throw new IllegalBlockingModeException();
+                writeFullyImpl(ch, bb);
+            }
+        } else {
+            writeFullyImpl(ch, bb);
+        }
+    }
+
+    /**
+     * @param ch The channel wrapped by this stream.
+     */
+    public ChannelOutputStream(WritableByteChannel ch) {
+        this.ch = ch;
+    }
+
+    /**
+     * @return The channel wrapped by this stream.
+     */
+    WritableByteChannel channel() {
+        return ch;
+    }
+
+    @Override
+    public synchronized void write(int b) throws IOException {
+        if (b1 == null)
+            b1 = new byte[1];
+        b1[0] = (byte) b;
+        this.write(b1);
+    }
+
+    @Override
+    public synchronized void write(byte[] bs, int off, int len)
+        throws IOException {
+        Objects.checkFromIndexSize(off, len, bs.length);
+        if (len == 0) {
+            return;
+        }
+        ByteBuffer bb = ((this.bs == bs)
+                         ? this.bb
+                         : ByteBuffer.wrap(bs));
+        bb.limit(Math.min(off + len, bb.capacity()));
+        bb.position(off);
+        this.bb = bb;
+        this.bs = bs;
+        writeFully(ch, bb);
+    }
+
+    @Override
+    public void close() throws IOException {
+        ch.close();
+    }
+
+}