1 /*

     2  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  */

    23 

    24 /*

    25  * @test

    26  * @bug 8010837

    27  * @summary Test if available returns correct value when skipping beyond

    28  *          the end of a file.

    29  * @author Dan Xu

    30  */

    31 

    32 import java.io.BufferedWriter;

    33 import java.io.File;

    34 import java.io.FileInputStream;

    35 import java.io.IOException;

    36 import java.nio.charset.Charset;

    37 import java.nio.file.Files;

    38 import java.nio.file.Path;

    39 

    40 public class NegativeAvailable {

    41 

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

    43         final int SIZE = 10;

    44         final int SKIP = 5;

    45 

    46         // Create a temporary file with size of 10 bytes.

    47         Path tmp = Files.createTempFile(null, null);

    48         try (BufferedWriter writer =

    49             Files.newBufferedWriter(tmp, Charset.defaultCharset())) {

    50             for (int i = 0; i < SIZE; i++) {

    51                 writer.write('1');

    52             }

    53         }

    54 

    55         File tempFile = tmp.toFile();

    56         try (FileInputStream fis = new FileInputStream(tempFile)) {

    57             if (tempFile.length() != SIZE) {

    58                 throw new RuntimeException("unexpected file size = "

    59                     + tempFile.length());

    60             }

    61             long space = skipBytes(fis, SKIP, SIZE);

    62             space = skipBytes(fis, SKIP, space);

    63             space = skipBytes(fis, SKIP, space);

    64             space = skipBytes(fis, SKIP, space);

    65         }

    66         Files.deleteIfExists(tmp);

    67     }

    68 

    69     /**

    70      *  Skip toSkip number of bytes and return the remaining bytes of the file.

    71      */

    72     private static long skipBytes(FileInputStream fis, int toSkip, long space)

    73             throws IOException {

    74         long skip = fis.skip(toSkip);

    75         if (skip != toSkip) {

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

    77                 + " but expected " + toSkip);

    78         }

    79         long remaining = space - toSkip;

    80         int avail = fis.available();

    81         if (avail != remaining) {

    82             throw new RuntimeException("available() returns " + avail

    83                 + " but expected " + remaining);

    84         }

    85 

    86         System.out.println("Skipped " + skip + " bytes "

    87             + " available() returns " + avail);

    88         return remaining;

    89     }

    90 }