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.Posix;
  34
  35 namespace Beagle.Util {
  36
  37         public class ExtendedAttribute {
  38
  39                 // FIXME: Once Mono 1.1/1.2 is required, we should start using the
  40                 // xattr bindings which are now present in the Mono.Unix.Syscall class.
  41                 // The interface provided via Syscall in future Mono versions will support both
  42                 // Linux/FreeBSD attributes transparently.
  43
  44                 // Linux xattrs
  45                 [DllImport (ExternalStringsHack.XattrLib, SetLastError=true)]
  46                 static extern int lsetxattr (string path, string name, byte[] value, uint size, int flags);
  47
  48                 [DllImport (ExternalStringsHack.XattrLib, SetLastError=true)]
  49                 static extern int lgetxattr (string path, string name, byte[] value, uint size);
  50
  51                 [DllImport (ExternalStringsHack.XattrLib, SetLastError=true)]
  52                 static extern int lremovexattr (string path, string name);
  53
  54                 // FreeBSD extattrs
  55                 // Very similar to Linux xattrs, but the namespace is provided as a
  56                 // parameter as opposed to a string prefix to the name.
  57                 [DllImport (ExternalStringsHack.XattrLib, SetLastError=true)]
  58                 static extern int extattr_set_link (string path, int attrnamespace, string attrname, byte[] value, uint size);
  59
  60                 [DllImport (ExternalStringsHack.XattrLib, SetLastError=true)]
  61                 static extern int extattr_get_link (string path, int attrnamespace, string attrname, byte[] value, uint size);
  62
  63                 [DllImport (ExternalStringsHack.XattrLib, SetLastError=true)]
  64                 static extern int extattr_delete_link (string path, int attrnamespace, string attrname);
  65
  66                 private static string AddPrefix (string name)
  67                 {
  68 #if OS_LINUX
  69                         return "user.Beagle." + name;
  70 #elif OS_FREEBSD
  71                         return "Beagle." + name;
  72 #endif
  73                 }
  74
  75                 static Encoding encoding = new UTF8Encoding ();
  76
  77                 public static void Set (string path, string name, string value)
  78                 {
  79                         if (! FileSystem.Exists (path))
  80                                 throw new IOException (path);
  81
  82                         name = AddPrefix (name);
  83
  84                         byte[] buffer = encoding.GetBytes (value);
  85 #if OS_LINUX
  86                         int retval = lsetxattr (path, name, buffer, (uint) buffer.Length, 0);
  87 #elif OS_FREEBSD
  88                         int retval = extattr_set_link (path, 1, name, buffer, (uint) buffer.Length);
  89 #endif
  90                         if (retval == -1)
  91                                 throw new IOException ("Could not set extended attribute on " + path + ": " + Syscall.strerror (Marshal.GetLastWin32Error ()));
  92                 }
  93
  94                 public static bool Exists (string path, string name)
  95                 {
  96                         if (! FileSystem.Exists (path))
  97                                 throw new IOException (path);
  98
  99                         name = AddPrefix (name);
 100
 101                         byte[] buffer = null;
 102 #if OS_LINUX
 103                         int size = lgetxattr (path, name, buffer, 0);
 104 #elif OS_FREEBSD
 105                         int size = extattr_get_link (path, 1, name, buffer, 0);
 106 #endif
 107
 108                         return size <= 0;
 109                 }
 110
 111                 public static string Get (string path, string name)
 112                 {
 113                         if (! FileSystem.Exists (path))
 114                                 throw new IOException (path);
 115
 116                         name = AddPrefix (name);
 117
 118                         byte[] buffer = null;
 119 #if OS_LINUX
 120                         int size = lgetxattr (path, name, buffer, 0);
 121 #elif OS_FREEBSD
 122                         int size = extattr_get_link (path, 1, name, buffer, 0);
 123 #endif
 124                         if (size <= 0)
 125                                 return null;
 126                         buffer = new byte [size];
 127 #if OS_LINUX
 128                         int retval = lgetxattr (path, name, buffer, (uint) size);
 129 #elif OS_FREEBSD
 130                         int retval = extattr_get_link (path, 1, name, buffer, (uint) size);
 131 #endif
 132                         if (retval < 0)
 133                                 throw new IOException ("Could not get extended attribute on " + path + ": " + Syscall.strerror (Marshal.GetLastWin32Error ()));
 134
 135                         return encoding.GetString (buffer);
 136                 }
 137
 138                 public static void Remove (string path, string name)
 139                 {
 140                         if (! FileSystem.Exists (path))
 141                                 throw new IOException (path);
 142
 143                         name = AddPrefix (name);
 144
 145 #if OS_LINUX
 146                         int retval = lremovexattr (path, name);
 147 #elif OS_FREEBSD
 148                         int retval = extattr_delete_link (path, 1, name);
 149 #endif
 150                         if (retval != 0)
 151                                 throw new IOException ("Could not remove extended attribute on " + path + ": " + Syscall.strerror (Marshal.GetLastWin32Error ()));
 152                 }
 153
 154                 // Check to see if it is possible to get and set attributes on a given file.
 155                 public static bool Test (string path)
 156                 {
 157                         const string test_key = "__test_key__";
 158                         const string test_value = "__test_value__";
 159
 160                         try {
 161                                 Set (path, test_key, test_value);
 162                                 if (Get (path, test_key) != test_value)
 163                                         return false;
 164                                 Remove (path, test_key);
 165                                 return Get (path, test_key) == null;
 166
 167                         } catch (Exception ex) {
 168                                 return false;
 169                         }
 170                 }
 171
 172                 private static bool ea_support_tested = false;
 173                 private static bool ea_supported = false;
 174
 175                 public static bool Supported {
 176                         get {
 177                                 if (ea_support_tested)
 178                                         return ea_supported;
 179
 180                                 ea_supported = Test (PathFinder.HomeDir);
 181                                 ea_support_tested = true;
 182
 183                                 return ea_supported;
 184                         }
 185                 }
 186         }
 187 }