Util/ExtendedAttribute.cs

   1 //
   2 // ExtendedAttribute.cs
   3 //
   4 // Copyright (C) 2004 Novell, Inc.
   5 //
   6
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining a
   9 // copy of this software and associated documentation files (the "Software"),
  10 // to deal in the Software without restriction, including without limitation
  11 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12 // and/or sell copies of the Software, and to permit persons to whom the
  13 // Software is furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in
  16 // all copies or substantial portions of the Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24 // DEALINGS IN THE SOFTWARE.
  25 //
  26
  27 // FIXME: This is not portable to Win32
  28
  29 using System;
  30 using System.IO;
  31 using System.Text;
  32 using System.Runtime.InteropServices;
  33 using Mono.Unix.Native;
  34
  35 namespace Beagle.Util {
  36
  37         public class ExtendedAttribute {
  38
  39                 private static string AddPrefix (string name)
  40                 {
  41                         return "user.Beagle." + name;
  42                 }
  43
  44                 static Encoding encoding = new UTF8Encoding ();
  45
  46                 public static void Set (string path, string name, string value)
  47                 {
  48                         if (! FileSystem.Exists (path))
  49                                 throw new IOException (path);
  50
  51                         name = AddPrefix (name);
  52
  53                         byte[] buffer = encoding.GetBytes (value);
  54                         int retval = Syscall.lsetxattr (path, name, buffer);
  55                         if (retval == -1)
  56                                 throw new IOException ("Could not set extended attribute on " + path + ": " + Mono.Unix.Native.Stdlib.strerror (Mono.Unix.Native.Stdlib.GetLastError ()));
  57                 }
  58
  59                 public static bool Exists (string path, string name)
  60                 {
  61                         if (! FileSystem.Exists (path))
  62                                 throw new IOException (path);
  63
  64                         name = AddPrefix (name);
  65
  66                         long size = Syscall.lgetxattr (path, name, null, 0);
  67                         return size >= 0;
  68                 }
  69
  70                 public static string Get (string path, string name)
  71                 {
  72                         if (! FileSystem.Exists (path))
  73                                 throw new IOException (path);
  74
  75                         name = AddPrefix (name);
  76
  77                         byte[] buffer;
  78                         long size = Syscall.lgetxattr (path, name, out buffer);
  79                         if (size <= 0)
  80                                 return null;
  81                         return encoding.GetString (buffer);
  82                 }
  83
  84                 public static void Remove (string path, string name)
  85                 {
  86                         if (! FileSystem.Exists (path))
  87                                 throw new IOException (path);
  88
  89                         name = AddPrefix (name);
  90
  91                         int retval = Syscall.lremovexattr (path, name);
  92                         if (retval != 0)
  93                                 throw new IOException ("Could not remove extended attribute on " + path + ": " + Mono.Unix.Native.Stdlib.strerror (Mono.Unix.Native.Stdlib.GetLastError ()));
  94                 }
  95
  96                 // Check to see if it is possible to get and set attributes on a given file.
  97                 public static bool Test (string path)
  98                 {
  99                         const string test_key = "__test_key__";
 100                         const string test_value = "__test_value__";
 101
 102                         try {
 103                                 Set (path, test_key, test_value);
 104                                 if (Get (path, test_key) != test_value)
 105                                         return false;
 106                                 Remove (path, test_key);
 107                                 return Get (path, test_key) == null;
 108
 109                         } catch (Exception ex) {
 110                                 return false;
 111                         }
 112                 }
 113
 114                 private static bool ea_support_tested = false;
 115                 private static bool ea_supported = false;
 116
 117                 public static bool Supported {
 118                         get {
 119                                 if (ea_support_tested)
 120                                         return ea_supported;
 121
 122                                 ea_supported = Test (PathFinder.HomeDir);
 123                                 ea_support_tested = true;
 124
 125                                 return ea_supported;
 126                         }
 127                 }
 128         }
 129 }