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 * 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 6402006 7030573 8011136

 * @summary Test if available returns correct value when reading

 *          a large file.

 * @run main/timeout=300 LargeFileAvailable

 */

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.channels.*;

import java.nio.file.Files;

import static java.nio.file.StandardOpenOption.*;

import java.util.concurrent.TimeUnit;

public class LargeFileAvailable {

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

        // Create a temporary file in the current directory.

        // Use it to check if we have 7G available for

        // a large sparse file test. As a fallback use whatever

        // space is available, so the test can proceed.

        File file = File.createTempFile("largefile", null, new File("."));

        long spaceavailable = file.getUsableSpace();

        long filesize = Math.min(spaceavailable,  7405576182L);

        if (spaceavailable == 0L) {

            // A full disk is considered fatal.

            throw new RuntimeException("No space available for temp file.");

        }

        createLargeFile(filesize, file);

        try (FileInputStream fis = new FileInputStream(file)) {

            if (file.length() != filesize) {

                throw new RuntimeException("unexpected file size = "

                                           + file.length());

            }

            long bigSkip = Math.min(filesize/2, 3110608882L);

            long remaining = filesize;

            remaining -= skipBytes(fis, bigSkip, remaining);

            remaining -= skipBytes(fis, 10L, remaining);

            remaining -= skipBytes(fis, bigSkip, remaining);

            int expected = (remaining >= Integer.MAX_VALUE)

                           ? Integer.MAX_VALUE

                           : (remaining > 0 ? (int) remaining : 0);

            if (fis.available() != expected) {

                throw new RuntimeException("available() returns "

                        + fis.available() + " but expected " + expected);

            }

        } finally {

            file.delete();

        }

        System.out.println("Test succeeded.");

        System.out.flush();

    }

    // Skip toSkip number of bytes and expect that the available() method

    // returns avail number of bytes.

    private static long skipBytes(InputStream is, long toSkip, long avail)

            throws IOException {

        long skip = is.skip(toSkip);

        if (skip != toSkip) {

            throw new RuntimeException("skip() returns " + skip

                                       + " but expected " + toSkip);

        }

        long remaining = avail - skip;

        int expected = (remaining >= Integer.MAX_VALUE)

                       ? Integer.MAX_VALUE

                       : (remaining > 0 ? (int) remaining : 0);

        System.out.println("Skipped " + skip + " bytes, available() returns "

                           + expected + ", remaining " + remaining);

        if (is.available() != expected) {

            throw new RuntimeException("available() returns "

                    + is.available() + " but expected " + expected);

        }

        return skip;

    }

    private static void createLargeFile(long filesize,

                                        File file) throws Exception {

        // Recreate a large file as a sparse file if possible

        Files.delete(file.toPath());

        try (FileChannel fc =

             FileChannel.open(file.toPath(),

                              CREATE_NEW, WRITE, SPARSE)) {

            ByteBuffer bb = ByteBuffer.allocate(1).put((byte)1);

            bb.rewind();

            System.out.println("  Writing large file...");

            long t0 = System.nanoTime();

            int rc = fc.write(bb, filesize - 1);

            long t1 = System.nanoTime();

            System.out.printf("  Wrote large file in %d ns (%d ms) %n",

                t1 - t0, TimeUnit.NANOSECONDS.toMillis(t1 - t0));

            if (rc != 1) {

                throw new RuntimeException("Failed to write 1 byte"

                                           + " to the large file");

            }

        }

        return;

    }

}