/*

 * Copyright (c) 2000, 2010, 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 4862411

 * @summary Test positional write method of FileChannel

 * @key randomness

 */

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.CharBuffer;

import java.nio.channels.*;

import java.nio.channels.FileChannel;

import java.util.Random;

/**

 * Testing FileChannel's positional write method.

 */

public class Pwrite {

    private static Random generator = new Random();

    private static File blah;

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

        genericTest();

        testUnwritableChannel();

    }

    // This test for bug 4862411

    private static void testUnwritableChannel() throws Exception {

        File blah = File.createTempFile("blah2", null);

        blah.deleteOnExit();

        FileOutputStream fos = new FileOutputStream(blah);

        fos.write(new byte[128]);

        fos.close();

        FileInputStream fis = new FileInputStream(blah);

        FileChannel fc = fis.getChannel();

        try {

            fc.write(ByteBuffer.allocate(256),1);

            throw new RuntimeException("Expected exception not thrown");

        } catch(NonWritableChannelException e) {

            // Correct result

        } finally {

            fc.close();

            blah.delete();

        }

    }

    private static void genericTest() throws Exception {

        StringBuffer sb = new StringBuffer();

        sb.setLength(4);

        blah = File.createTempFile("blah", null);

        blah.deleteOnExit();

        initTestFile(blah);

        RandomAccessFile raf = new RandomAccessFile(blah, "rw");

        FileChannel c = raf.getChannel();

        for (int x=0; x<100; x++) {

            long offset = generator.nextInt(1000);

            ByteBuffer bleck = ByteBuffer.allocateDirect(4);

            // Write known sequence out

            for (byte i=0; i<4; i++) {

                bleck.put(i);

            }

            bleck.flip();

            long originalPosition = c.position();

            int totalWritten = 0;

            while (totalWritten < 4) {

                int written = c.write(bleck, offset);

                if (written < 0)

                    throw new Exception("Read failed");

                totalWritten += written;

            }

            long newPosition = c.position();

            // Ensure that file pointer position has not changed

            if (originalPosition != newPosition)

                throw new Exception("File position modified");

            // Attempt to read sequence back in

            bleck = ByteBuffer.allocateDirect(4);

            originalPosition = c.position();

            int totalRead = 0;

            while (totalRead < 4) {

                int read = c.read(bleck, offset);

                if (read < 0)

                    throw new Exception("Read failed");

                totalRead += read;

            }

            newPosition = c.position();

            // Ensure that file pointer position has not changed

            if (originalPosition != newPosition)

                throw new Exception("File position modified");

            for (byte i=0; i<4; i++) {

                if (bleck.get(i) != i)

                    throw new Exception("Write test failed");

            }

        }

        c.close();

        raf.close();

        blah.delete();

    }

    /**

     * Creates file blah:

     * 0000

     * 0001

     * 0002

     * 0003

     * .

     * .

     * .

     * 3999

     *

     * Blah extends beyond a single page of memory so that the

     * ability to index into a file of multiple pages is tested.

     */

    private static void initTestFile(File blah) throws Exception {

        FileOutputStream fos = new FileOutputStream(blah);

        BufferedWriter awriter

            = new BufferedWriter(new OutputStreamWriter(fos, "8859_1"));

        for(int i=0; i<4000; i++) {

            String number = new Integer(i).toString();

            for (int h=0; h<4-number.length(); h++)

                awriter.write("0");

            awriter.write(""+i);

            awriter.newLine();

        }

       awriter.flush();

       awriter.close();

    }

}