mcs/class/corlib/System.Security.Permissions/SecurityPermission.cs

   1 //
   2 // System.Security.Permissions.SecurityPermission.cs
   3 //
   4 // Authors:
   5 //      Dan Lewis (dihlewis@yahoo.co.uk)
   6 //      Sebastien Pouliot  <sebastien@ximian.com>
   7 //
   8 // (C) 2002
   9 // Portions (C) 2003 Motus Technologies Inc. (http://www.motus.com)
  10 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System.Globalization;
  33 using System.Runtime.InteropServices;
  34
  35 namespace System.Security.Permissions {
  36
  37 #if NET_2_0
  38         [ComVisible (true)]
  39 #endif
  40
  41         [Serializable]
  42         public sealed class SecurityPermission :
  43                 CodeAccessPermission, IUnrestrictedPermission, IBuiltInPermission {
  44
  45                 private const int version = 1;
  46
  47                 private SecurityPermissionFlag flags;
  48
  49                 // constructors
  50
  51                 public SecurityPermission (PermissionState state)
  52                 {
  53                         if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
  54                                 flags = SecurityPermissionFlag.AllFlags;
  55                         else
  56                                 flags = SecurityPermissionFlag.NoFlags;
  57                 }
  58
  59                 public SecurityPermission (SecurityPermissionFlag flags)
  60                 {
  61                         // reuse validation by the Flags property
  62                         Flags = flags;
  63                 }
  64
  65                 public SecurityPermissionFlag Flags {
  66                         get { return flags; }
  67                         set {
  68                                 if ((value & SecurityPermissionFlag.AllFlags) != value) {
  69                                         string msg = String.Format (Locale.GetText ("Invalid flags {0}"), value);
  70                                         throw new ArgumentException (msg, "SecurityPermissionFlag");
  71                                 }
  72                                 flags = value;
  73                         }
  74                 }
  75
  76                 // IUnrestrictedPermission
  77                 public bool IsUnrestricted ()
  78                 {
  79                         return (flags == SecurityPermissionFlag.AllFlags);
  80                 }
  81
  82                 public override IPermission Copy ()
  83                 {
  84                         return new SecurityPermission (flags);
  85                 }
  86
  87                 public override IPermission Intersect (IPermission target)
  88                 {
  89                         SecurityPermission sp = Cast (target);
  90                         if (sp == null)
  91                                 return null;
  92                         if (IsEmpty () || sp.IsEmpty ())
  93                                 return null;
  94
  95                         if (this.IsUnrestricted () && sp.IsUnrestricted ())
  96                                 return new SecurityPermission (PermissionState.Unrestricted);
  97                         if (this.IsUnrestricted ())
  98                                 return sp.Copy ();
  99                         if (sp.IsUnrestricted ())
 100                                 return this.Copy ();
 101
 102                         SecurityPermissionFlag f = flags & sp.flags;
 103                         if (f == SecurityPermissionFlag.NoFlags)
 104                                 return null;
 105                         else
 106                                 return new SecurityPermission (f);
 107                 }
 108
 109                 public override IPermission Union (IPermission target)
 110                 {
 111                         SecurityPermission sp = Cast (target);
 112                         if (sp == null)
 113                                 return this.Copy ();
 114
 115                         if (this.IsUnrestricted () || sp.IsUnrestricted ())
 116                                 return new SecurityPermission (PermissionState.Unrestricted);
 117
 118                         return new SecurityPermission (flags | sp.flags);
 119                 }
 120
 121                 public override bool IsSubsetOf (IPermission target)
 122                 {
 123                         SecurityPermission sp = Cast (target);
 124                         if (sp == null)
 125                                 return IsEmpty ();
 126
 127                         if (sp.IsUnrestricted ())
 128                                 return true;
 129                         if (this.IsUnrestricted ())
 130                                 return false;
 131
 132                         return ((flags & ~sp.flags) == 0);
 133                 }
 134
 135                 public override void FromXml (SecurityElement e)
 136                 {
 137                         // General validation in CodeAccessPermission
 138                         CheckSecurityElement (e, "e", version, version);
 139                         // Note: we do not (yet) care about the return value
 140                         // as we only accept version 1 (min/max values)
 141
 142                         if (IsUnrestricted (e)) {
 143                                 flags = SecurityPermissionFlag.AllFlags;
 144                         }
 145                         else {
 146                                 string f = e.Attribute ("Flags");
 147                                 if (f == null) {
 148                                         flags = SecurityPermissionFlag.NoFlags;
 149                                 }
 150                                 else {
 151                                         flags = (SecurityPermissionFlag) Enum.Parse (
 152                                                 typeof (SecurityPermissionFlag), f);
 153                                 }
 154                         }
 155                 }
 156
 157                 public override SecurityElement ToXml ()
 158                 {
 159                         SecurityElement e = Element (version);
 160                         if (IsUnrestricted ())
 161                                 e.AddAttribute ("Unrestricted", "true");
 162                         else
 163                                 e.AddAttribute ("Flags", flags.ToString ());
 164                         return e;
 165                 }
 166
 167                 // IBuiltInPermission
 168                 int IBuiltInPermission.GetTokenIndex ()
 169                 {
 170                         return (int) BuiltInToken.Security;
 171                 }
 172
 173                 // helpers
 174
 175                 private bool IsEmpty ()
 176                 {
 177                         return (flags == SecurityPermissionFlag.NoFlags);
 178                 }
 179
 180                 private SecurityPermission Cast (IPermission target)
 181                 {
 182                         if (target == null)
 183                                 return null;
 184
 185                         SecurityPermission sp = (target as SecurityPermission);
 186                         if (sp == null) {
 187                                 ThrowInvalidPermission (target, typeof (SecurityPermission));
 188                         }
 189
 190                         return sp;
 191                 }
 192         }
 193 }