1 /*
   2  * Copyright (c) 1997, 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 4016710
  27    @summary check for correct implementation of InputStream.skip
  28    */
  29 
  30 import java.io.*;
  31 
  32 
  33 public class Skip{
  34 
  35     private static void dotest(InputStream in , int curpos ,
  36                                long total , long toskip , long expected)
  37         throws Exception
  38     {
  39 
  40         try {
  41 
  42             System.err.println("\n\nCurrently at pos = " + curpos +
  43                                "\nTotal bytes in the Stream = " + total +
  44                                "\nNumber of bytes to skip = " + toskip +
  45                                "\nNumber of bytes that should be skipped = " +
  46                                expected);
  47 
  48             long skipped = in.skip(toskip);
  49 
  50             System.err.println("actual number skipped: "+ skipped);
  51 
  52             if ((skipped < 0) || (skipped > expected)) {
  53                 throw new RuntimeException("Unexpected number of bytes skipped");
  54             }
  55 
  56         } catch (IOException e) {
  57             System.err.println("IOException is thrown - possible result");
  58         } catch (Throwable e) {
  59             throw new RuntimeException("Unexpected "+e+" is thrown!");
  60         }
  61 
  62     }
  63 
  64     public static void main( String argv[] ) throws Exception {
  65 
  66         MyInputStream in = new MyInputStream(11);
  67 
  68         /* test for negative skip */
  69         dotest(in,  0, 11, -23,  0);
  70 
  71         /* check for skip beyond EOF starting from before EOF */
  72         dotest(in,  0, 11,  20, 11);
  73 
  74         /* check for skip after EOF */
  75         dotest(in, -1, 11,  20,  0);
  76 
  77         in = new MyInputStream(9000);
  78         /* check for skip equal to the read chunk size in InputStream.java */
  79         dotest(in,  0, 9000, 2048, 2048);
  80 
  81         /* check for skip greater than the read chunk size in InputStream.java */
  82         dotest(in, 2048, 9000, 5000, 5000);
  83 
  84         /* check for skip beyond EOF starting from before EOF */
  85         dotest(in, 7048, 9000, 5000, 1952);
  86 
  87         in = new MyInputStream(5000);
  88 
  89         /* check for multiple chunk reads */
  90         dotest(in, 0, 5000, 6000, 5000);
  91 
  92         /*
  93          * check for skip larger than Integer.MAX_VALUE
  94          * (Takes about 2 hrs on a sparc ultra-1)
  95          * long total = (long)Integer.MAX_VALUE + (long)10;
  96          * long toskip = total - (long)6;
  97          * in = new MyInputStream(total);
  98          * dotest(in, 0, total, toskip, toskip);
  99          */
 100 
 101     }
 102 
 103 }
 104 
 105 class MyInputStream extends InputStream {
 106 
 107     private int readctr = 0;
 108     private long endoffile;
 109 
 110     public MyInputStream(long endoffile) {
 111         this.endoffile = endoffile;
 112     }
 113 
 114     public int read() {
 115 
 116         if (readctr == endoffile) {
 117             return -1;
 118         }
 119         else {
 120             readctr++;
 121             return 0;
 122         }
 123     }
 124 
 125     public int available() { return 0; }
 126 }