mcs/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 // (C) 2004 Novell (http://www.novell.com)
  10 //
  11
  12 using System;
  13 using System.Runtime.CompilerServices;
  14 using System.Security;
  15
  16 namespace System.Security.Principal {
  17
  18         public class WindowsImpersonationContext {
  19
  20                 private IntPtr _token;
  21                 private bool undo;
  22
  23                 internal WindowsImpersonationContext (IntPtr token)
  24                 {
  25                         // we get a copy to control it's lifetime
  26                         _token = DuplicateToken (token);
  27                         if (!SetCurrentToken (token)) {
  28                                 throw new SecurityException ("Couldn't impersonate token.");
  29                         }
  30                         undo = false;
  31                 }
  32
  33                 ~WindowsImpersonationContext ()
  34                 {
  35                         if (!undo) {
  36                                 Undo ();
  37                         }
  38                 }
  39
  40                 public void Undo ()
  41                 {
  42                         if (!RevertToSelf ()) {
  43                                 CloseToken (_token);
  44                                 throw new SecurityException ("Couldn't switch back to original token.");
  45                         }
  46                         CloseToken (_token);
  47                         undo = true;
  48                         GC.SuppressFinalize (this);
  49                 }
  50
  51                 // see mono/mono/metadata/security.c for implementation
  52
  53                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  54                 private extern static bool CloseToken (IntPtr token);
  55
  56                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  57                 private extern static IntPtr DuplicateToken (IntPtr token);
  58
  59                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  60                 private extern static bool SetCurrentToken (IntPtr token);
  61
  62                 [MethodImplAttribute (MethodImplOptions.InternalCall)]
  63                 private extern static bool RevertToSelf ();
  64         }
  65 }