/*

 * Copyright (c) 2017, 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

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 * questions.

 */

/* @test

 * @bug 8164900

 * @summary Test positional read method of FileChannel with DirectIO

 * (use -Dseed=X to set PRNG seed)

 * @library .. /test/lib

 * @build jdk.test.lib.RandomFactory

 *        DirectIOTest

 * @run main/othervm PreadDirect

 * @key randomness

 */

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.CharBuffer;

import java.nio.channels.*;

import java.nio.file.Files;

import java.nio.file.FileStore;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

import java.util.Random;

import com.sun.nio.file.ExtendedOpenOption;

import jdk.test.lib.RandomFactory;

/**

 * Testing FileChannel's positional read method.

 */

public class PreadDirect {

    private static PrintStream err = System.err;

    private static Random generator = RandomFactory.getRandom();

    private static int charsPerGroup = -1;

    private static int alignment = -1;

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

        if (initTests()) {

            genericTest();

            testNotAlignedChannelPosition();

            testNegativeChannelPosition();

        }

    }

    private static boolean initTests() throws Exception {

        Path p = DirectIOTest.createTempFile();

        if (!DirectIOTest.isDirectIOSupportedByFS(p)) {

            Files.delete(p);

            return false;

        }

        try {

            FileStore fs = Files.getFileStore(p);

            alignment = (int)fs.getBlockSize();

            charsPerGroup = alignment;

        } finally {

            Files.delete(p);

        }

        return true;

    }

    private static void testNegativeChannelPosition() throws Exception {

        Path p = DirectIOTest.createTempFile();

        try (OutputStream fos = Files.newOutputStream(p)) {

            fos.write(new byte[charsPerGroup]);

        }

        try (FileChannel fc = FileChannel.open(p,

            StandardOpenOption.DELETE_ON_CLOSE, ExtendedOpenOption.DIRECT)) {

            try {

                fc.read(ByteBuffer.allocate(charsPerGroup), -1L);

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

            } catch(IllegalArgumentException e) {

                // Correct result

            }

        }

    }

    private static void testNotAlignedChannelPosition() throws Exception {

        Path p = DirectIOTest.createTempFile();

        try (OutputStream fos = Files.newOutputStream(p)) {

            fos.write(new byte[charsPerGroup]);

        }

        try (FileChannel fc = FileChannel.open(p,

            StandardOpenOption.DELETE_ON_CLOSE, ExtendedOpenOption.DIRECT)) {

            long pos = charsPerGroup - 1;

            try {

                fc.read(ByteBuffer.allocate(charsPerGroup), pos);

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

            } catch(IOException e) {

                if (!e.getMessage().contains("Channel position (" + pos

                    + ") is not a multiple of the block size (" + alignment + ")"))

                    throw new RuntimeException("Read test failed");

            }

        }

    }

    private static void genericTest() throws Exception {

        StringBuffer sb = new StringBuffer();

        sb.setLength(2);

        Path p = DirectIOTest.createTempFile();

        initTestFile(p);

        try (FileChannel fc = FileChannel.open(p,

            StandardOpenOption.DELETE_ON_CLOSE, ExtendedOpenOption.DIRECT)) {

            ByteBuffer block =

                ByteBuffer.allocateDirect(charsPerGroup + alignment - 1)

                          .alignedSlice(alignment);

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

                block.clear();

                long offset = generator.nextInt(100) * charsPerGroup;

                long expectedResult = offset / charsPerGroup;

                offset = expectedResult * charsPerGroup;

                long originalPosition = fc.position();

                int read = fc.read(block, offset);

                if (read != charsPerGroup)

                    throw new Exception("Read failed");

                long newPosition = fc.position();

                for (int i = 0; i < 2; i++) {

                    byte aByte = block.get(i);

                    sb.setCharAt(i, (char)aByte);

                }

                int result = Integer.parseInt(sb.toString());

                if (result != expectedResult) {

                    err.println("I expected "+ expectedResult);

                    err.println("I got "+ result);

                    throw new Exception("Read test failed");

                }

                // Ensure that file pointer position has not changed

                if (originalPosition != newPosition)

                    throw new Exception("File position modified");

            }

        }

    }

    private static void initTestFile(Path p) throws Exception {

        try (OutputStream fos = Files.newOutputStream(p)) {

            try (BufferedWriter awriter

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

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

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

                    for (int h = 0; h < 2 - number.length(); h++)

                        awriter.write("0");

                    awriter.write(""+i);

                    for (int j = 0; j < (charsPerGroup - 2); j++)

                        awriter.write("0");

                }

                awriter.flush();

            }

        }

    }

}