/*
 * Copyright (c) 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
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 * questions.
 */

/*
 * @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 static java.nio.file.StandardOpenOption.*;

public class LargeFileAvailable {
    private static final long FILESIZE = 7405576182L;
    private static long skippedBytes = 0;
    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 pos = 3110608882L;
            skipBytes(fis, pos, Integer.MAX_VALUE);
            skipBytes(fis, 10L, Integer.MAX_VALUE);
    
            Long remaining = new Long(FILESIZE-pos-10-pos);
            skipBytes(fis, pos, remaining.intValue());
        } finally {
            file.delete();
        }
    }

    // Skip toSkip number of bytes and expect that the available() method
    // returns avail number of bytes.
    private static void skipBytes(InputStream is, long toSkip, int avail) 
            throws IOException {
        long skip = is.skip(toSkip);
        if (skip != toSkip) {
             throw new RuntimeException("skip() returns " + skip +
                 " but expected " + toSkip);
        }
        skippedBytes += skip;
        int value = is.available();
        if (value != avail) {
             throw new RuntimeException("available() returns " + value +
                 " but expected " + avail);
        }
        System.out.println("skipped " + toSkip +
            " bytes remaining " + (FILESIZE - skippedBytes));
    }

    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
        largefile.toPath().delete();
        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");
            }
        }
        largefile.deleteOnExit();
        return largefile;
    }
}