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 beyong
  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 }