/*

 * 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

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 */

/*

 * @test

 * @bug 6402006

 * @summary Test if available returns correct value when reading

 *          a large file.

 */

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.channels.*;

import java.nio.file.Files;

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

public class LargeFileAvailable {

    private static final long FILESIZE = 7405576182L;

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

        File file = createLargeFile(FILESIZE);

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

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

                throw new RuntimeException("unexpected file size = " + file.length());

            }

            long bigSkip = 3110608882L;

            long remaining = FILESIZE;

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

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

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

            if (fis.available() != (int) remaining) {

                 throw new RuntimeException("available() returns " +

                     fis.available() +

                     " but expected " + remaining);

            }

        } finally {

            file.delete();

        }

    }

    // 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

                           : (int) remaining;

        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 File createLargeFile(long filesize) throws Exception {

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

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

        // re-create as a sparse file

        Files.delete(largefile.toPath());

        try (FileChannel fc =

                FileChannel.open(largefile.toPath(),

                                 CREATE_NEW, WRITE, SPARSE)) {

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

            bb.rewind();

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

            if (rc != 1) {

                throw new RuntimeException("Failed to write 1 byte to the large file");

            }

        }

        return largefile;

    }

}