class/corlib/System.Security.Principal/WindowsImpersonationContext.cs

   1 //
   2 // System.Security.Principal.WindowsImpersonationContext
   3 //
   4 // Authors:
   5 //      Gonzalo Paniagua Javier (gonzalo@ximian.com)
   6 //      Sebastien Pouliot  (sebastien@ximian.com)
   7 //
   8 // (C) 2002 Ximian, Inc (http://www.ximian.com)
   9 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System.Runtime.CompilerServices;
  32 using System.Runtime.InteropServices;
  33 using System.Security;
  34
  35 namespace System.Security.Principal {
  36
  37         [ComVisible (true)]
  38         public class WindowsImpersonationContext : IDisposable {
  39
  40                 private IntPtr _token;
  41                 private bool undo;
  42
  43                 internal WindowsImpersonationContext (IntPtr token)
  44                 {
  45                         // we get a copy to control it's lifetime
  46                         _token = DuplicateToken (token);
  47                         if (!SetCurrentToken (token)) {
  48                                 throw new SecurityException ("Couldn't impersonate token.");
  49                         }
  50                         undo = false;
  51                 }
  52                 [ComVisible (false)]
  53                 public void Dispose ()
  54                 {
  55                         if (!undo) {
  56                                 Undo ();
  57                         }
  58                 }
  59
  60                 [ComVisible (false)]
  61                 protected virtual void Dispose (bool disposing)
  62                 {
  63                         if (!undo) {
  64                                 Undo ();
  65                         }
  66                         if (disposing){
  67                                 // If we are explicitly disposed, we can avoid finalization.
  68                                 GC.SuppressFinalize (this);
  69                         }
  70                 }
  71
  72                 public void Undo ()
  73                 {
  74                         if (!RevertToSelf ()) {
  75                                 CloseToken (_token);
  76                                 throw new SecurityException ("Couldn't switch back to original token.");
  77                         }
  78                         CloseToken (_token);
  79                         undo = true;
  80                         GC.SuppressFinalize (this);
  81                 }
  82
  83                 // see mono/mono/metadata/security.c for implementation
  84
  85                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  86                 private extern static bool CloseToken (IntPtr token);
  87
  88                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  89                 private extern static IntPtr DuplicateToken (IntPtr token);
  90
  91                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  92                 private extern static bool SetCurrentToken (IntPtr token);
  93
  94                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  95                 private extern static bool RevertToSelf ();
  96         }
  97 }