/*

 * Copyright (c) 2018, 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.

 *

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 */

/* @test

 * @bug 8204310

 * @summary Check how FileChannel behaves if the file size/offset change via

 *          RAF.setLength() and other methods.

 * @run main TruncateRAF

 */

import java.io.File;

import java.io.RandomAccessFile;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

public class TruncateRAF {

    static void checkState(RandomAccessFile raf, FileChannel fch,

            long expectedOffset, long expectedLength)

        throws IOException

    {

        long rafLength = raf.length();

        long rafOffset = raf.getFilePointer();

        long fchLength = fch.size();

        long fchOffset = fch.position();

        if (rafLength != expectedLength)

            throw new RuntimeException("rafLength (" + rafLength + ") != " +

                    "expectedLength (" + expectedLength + ")");

        if (rafOffset != expectedOffset)

            throw new RuntimeException("rafOffset (" + rafOffset + ") != " +

                    "expectedOffset (" + expectedOffset + ")");

        if (fchLength != expectedLength)

            throw new RuntimeException("fchLength (" + fchLength + ") != " +

                    "expectedLength (" + expectedLength + ")");

        if (fchOffset != expectedOffset)

            throw new RuntimeException("fchOffset (" + fchOffset + ") != " +

                    "expectedOffset (" + expectedOffset + ")");

    }

    public static void main(String[] args) throws Throwable {

        File file = new File("tmp");

        try (RandomAccessFile raf = new RandomAccessFile(file, "rw");

             FileChannel fch = raf.getChannel()) {

            // initially empty

            checkState(raf, fch, 0, 0);

            // seeking beyond EOF

            raf.seek(42);

            checkState(raf, fch, 42, 0);

            // seeking beyond EOF

            fch.position(84);

            checkState(raf, fch, 84, 0);

            // writing at offset beyond EOF

            raf.write(1);

            checkState(raf, fch, 85, 85);

            // truncating

            raf.setLength(63);

            checkState(raf, fch, 63, 63);

            // writing at EOF

            fch.write(ByteBuffer.wrap(new byte[1]));

            checkState(raf, fch, 64, 64);

            // seeking at the middle

            fch.position(32);

            checkState(raf, fch, 32, 64);

            // truncating beyond offset

            fch.truncate(42);

            checkState(raf, fch, 32, 42);

            // truncating before offset

            fch.truncate(16);

            checkState(raf, fch, 16, 16);

            // writing at position beyond EOF

            fch.write(ByteBuffer.wrap(new byte[1]), 127);

            checkState(raf, fch, 16, 128);

            // writing at position before EOF

            fch.write(ByteBuffer.wrap(new byte[1]), 42);

            checkState(raf, fch, 16, 128);

            // truncating

            raf.setLength(64);

            checkState(raf, fch, 16, 64);

            // changing offset

            raf.seek(21);

            checkState(raf, fch, 21, 64);

            // skipping should change offset

            raf.skipBytes(4);

            checkState(raf, fch, 25, 64);

            // reading should change offset

            raf.read();

            checkState(raf, fch, 26, 64);

            // truncating to zero

            raf.setLength(0);

            checkState(raf, fch, 0, 0);

            // FileChannel cannot expand size

            fch.truncate(42);

            checkState(raf, fch, 0, 0);

            // expanding

            raf.setLength(42);

            checkState(raf, fch, 0, 42);

            // seeking beyond EOF

            raf.seek(512);

            checkState(raf, fch, 512, 42);

            // truncating to the same size

            fch.truncate(256);

            checkState(raf, fch, 256, 42);

            // truncating to the same size

            fch.truncate(42);

            checkState(raf, fch, 42, 42);

            // truncating to zero

            fch.truncate(0);

            checkState(raf, fch, 0, 0);

        }

    }

}