1 /*
   2  * Copyright (c) 2002, 2012, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.nio.ch;
  27 
  28 
  29 // Constants for reporting I/O status
  30 
  31 public final class IOStatus {
  32 
  33     private IOStatus() { }
  34 
  35     public static final int EOF = -1;              // End of file
  36     public static final int UNAVAILABLE = -2;      // Nothing available (non-blocking)
  37     public static final int INTERRUPTED = -3;      // System call interrupted
  38     public static final int UNSUPPORTED = -4;      // Operation not supported
  39     public static final int THROWN = -5;           // Exception thrown in JNI code
  40     public static final int UNSUPPORTED_CASE = -6; // This case not supported
  41 
  42     // The following two methods are for use in try/finally blocks where a
  43     // status value needs to be normalized before being returned to the invoker
  44     // but also checked for illegal negative values before the return
  45     // completes, like so:
  46     //
  47     //     int n = 0;
  48     //     try {
  49     //         begin();
  50     //         n = op(fd, buf, ...);
  51     //         return IOStatus.normalize(n);    // Converts UNAVAILABLE to zero
  52     //     } finally {
  53     //         end(n > 0);
  54     //         assert IOStatus.check(n);        // Checks other negative values
  55     //     }
  56     //
  57 
  58     public static int normalize(int n) {
  59         if (n == UNAVAILABLE)
  60             return 0;
  61         return n;
  62     }
  63 
  64     public static boolean check(int n) {
  65         return (n >= UNAVAILABLE);
  66     }
  67 
  68     public static long normalize(long n) {
  69         if (n == UNAVAILABLE)
  70             return 0;
  71         return n;
  72     }
  73 
  74     public static boolean check(long n) {
  75         return (n >= UNAVAILABLE);
  76     }
  77 
  78     // Return true iff n is not one of the IOStatus values
  79     public static boolean checkAll(long n) {
  80         return ((n > EOF) || (n < UNSUPPORTED_CASE));
  81     }
  82 
  83 }