/*

 * Copyright (c) 2000, 2019, 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.FileDescriptor;

import java.io.IOException;

/**

 * Allows different platforms to call different native methods

 * for read and write operations.

 */

abstract class NativeDispatcher {

    abstract int read(FileDescriptor fd, long address, int len)

        throws IOException;

    /**

     * Returns {@code true} if pread/pwrite needs to be synchronized with

     * position sensitive methods.

     */

    boolean needsPositionLock() {

        return false;

    }

    int pread(FileDescriptor fd, long address, int len, long position)

        throws IOException

    {

        throw new IOException("Operation Unsupported");

    }

    abstract long readv(FileDescriptor fd, long address, int len)

        throws IOException;

    abstract int write(FileDescriptor fd, long address, int len)

        throws IOException;

    int pwrite(FileDescriptor fd, long address, int len, long position)

        throws IOException

    {

        throw new IOException("Operation Unsupported");

    }

    abstract long writev(FileDescriptor fd, long address, int len)

        throws IOException;

    abstract void close(FileDescriptor fd) throws IOException;

    // Prepare the given fd for closing by duping it to a known internal fd

    // that's already closed.  This is necessary on some operating systems

    // (Solaris and Linux) to prevent fd recycling.

    //

    void preClose(FileDescriptor fd) throws IOException {

        // Do nothing by default; this is only needed on Unix

    }

    /**

     * Duplicates a file descriptor.

     * @param fd1 the file descriptor to duplicate

     * @param fd2 the new file descriptor, the socket or file that it is connected

     *            to will be closed by this method

     */

    void dup(FileDescriptor fd1, FileDescriptor fd2) throws IOException {

        throw new UnsupportedOperationException();

    }

}