1 /*
   2  * Copyright (c) 2010, 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 6402006
  27  * @summary Test if available returns correct value when reading
  28  *          a large file.
  29  */
  30 
  31 import java.io.*;
  32 import java.nio.ByteBuffer;
  33 import java.nio.channels.*;
  34 import static java.nio.file.StandardOpenOption.*;
  35 
  36 public class LargeFileAvailable {
  37     private static final long FILESIZE = 7405576182L;
  38     public static void main(String args[]) throws Exception {
  39         File file = createLargeFile(FILESIZE);
  40         try (FileInputStream fis = new FileInputStream(file)) {
  41             if (file.length() != FILESIZE) {
  42                 throw new RuntimeException("unexpected file size = " + file.length());
  43             }
  44 
  45             long bigSkip = 3110608882L;
  46             long remaining = FILESIZE;
  47             remaining -= skipBytes(fis, bigSkip, remaining);
  48             remaining -= skipBytes(fis, 10L, remaining);
  49             remaining -= skipBytes(fis, bigSkip, remaining);
  50             if (fis.available() != (int) remaining) {
  51                  throw new RuntimeException("available() returns " +
  52                      fis.available() +
  53                      " but expected " + remaining);
  54             }
  55         } finally {
  56             file.delete();
  57         }
  58     }
  59 
  60     // Skip toSkip number of bytes and expect that the available() method
  61     // returns avail number of bytes.
  62     private static long skipBytes(InputStream is, long toSkip, long avail)
  63             throws IOException {
  64         long skip = is.skip(toSkip);
  65         if (skip != toSkip) {
  66             throw new RuntimeException("skip() returns " + skip +
  67                 " but expected " + toSkip);
  68         }
  69         long remaining = avail - skip;
  70         int expected = remaining >= Integer.MAX_VALUE
  71                            ? Integer.MAX_VALUE
  72                            : (int) remaining;
  73 
  74         System.out.println("Skipped " + skip + " bytes " +
  75             " available() returns " + expected +
  76             " remaining=" + remaining);
  77         if (is.available() != expected) {
  78             throw new RuntimeException("available() returns " +
  79                 is.available() + " but expected " + expected);
  80         }
  81         return skip;
  82     }
  83 
  84     private static File createLargeFile(long filesize) throws Exception {
  85         // Create a large file as a sparse file if possible
  86         File largefile = File.createTempFile("largefile", null);
  87         // re-create as a sparse file
  88         largefile.toPath().delete();
  89         try (FileChannel fc =
  90                 FileChannel.open(largefile.toPath(),
  91                                  CREATE_NEW, WRITE, SPARSE)) {
  92             ByteBuffer bb = ByteBuffer.allocate(1).put((byte)1);
  93             bb.rewind();
  94             int rc = fc.write(bb, filesize-1);
  95             if (rc != 1) {
  96                 throw new RuntimeException("Failed to write 1 byte to the large file");
  97             }
  98         }
  99         return largefile;
 100     }
 101 }