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 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
  34 namespace System.Security.Permissions {
  35
  36         [Serializable]
  37         public sealed class SecurityPermission :
  38                 CodeAccessPermission, IUnrestrictedPermission, IBuiltInPermission {
  39
  40                 private const int version = 1;
  41
  42                 private SecurityPermissionFlag flags;
  43
  44                 // constructors
  45
  46                 public SecurityPermission (PermissionState state)
  47                 {
  48                         if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
  49                                 flags = SecurityPermissionFlag.AllFlags;
  50                         else
  51                                 flags = SecurityPermissionFlag.NoFlags;
  52                 }
  53
  54                 public SecurityPermission (SecurityPermissionFlag flags)
  55                 {
  56                         // reuse validation by the Flags property
  57                         Flags = flags;
  58                 }
  59
  60                 public SecurityPermissionFlag Flags {
  61                         get { return flags; }
  62                         set {
  63                                 if ((value & SecurityPermissionFlag.AllFlags) != value) {
  64                                         string msg = String.Format (Locale.GetText ("Invalid flags {0}"), value);
  65                                         throw new ArgumentException (msg, "SecurityPermissionFlag");
  66                                 }
  67                                 flags = value;
  68                         }
  69                 }
  70
  71                 // IUnrestrictedPermission
  72                 public bool IsUnrestricted ()
  73                 {
  74                         return (flags == SecurityPermissionFlag.AllFlags);
  75                 }
  76
  77                 public override IPermission Copy ()
  78                 {
  79                         return new SecurityPermission (flags);
  80                 }
  81
  82                 public override IPermission Intersect (IPermission target)
  83                 {
  84                         SecurityPermission sp = Cast (target);
  85                         if (sp == null)
  86                                 return null;
  87                         if (IsEmpty () || sp.IsEmpty ())
  88                                 return null;
  89
  90                         if (this.IsUnrestricted () && sp.IsUnrestricted ())
  91                                 return new SecurityPermission (PermissionState.Unrestricted);
  92                         if (this.IsUnrestricted ())
  93                                 return sp.Copy ();
  94                         if (sp.IsUnrestricted ())
  95                                 return this.Copy ();
  96
  97                         SecurityPermissionFlag f = flags & sp.flags;
  98                         if (f == SecurityPermissionFlag.NoFlags)
  99                                 return null;
 100                         else
 101                                 return new SecurityPermission (f);
 102                 }
 103
 104                 public override IPermission Union (IPermission target)
 105                 {
 106                         SecurityPermission sp = Cast (target);
 107                         if (sp == null)
 108                                 return this.Copy ();
 109
 110                         if (this.IsUnrestricted () || sp.IsUnrestricted ())
 111                                 return new SecurityPermission (PermissionState.Unrestricted);
 112
 113                         return new SecurityPermission (flags | sp.flags);
 114                 }
 115
 116                 public override bool IsSubsetOf (IPermission target)
 117                 {
 118                         SecurityPermission sp = Cast (target);
 119                         if (sp == null)
 120                                 return IsEmpty ();
 121
 122                         if (sp.IsUnrestricted ())
 123                                 return true;
 124                         if (this.IsUnrestricted ())
 125                                 return false;
 126
 127                         return ((flags & ~sp.flags) == 0);
 128                 }
 129
 130                 public override void FromXml (SecurityElement e)
 131                 {
 132                         // General validation in CodeAccessPermission
 133                         CheckSecurityElement (e, "e", version, version);
 134                         // Note: we do not (yet) care about the return value
 135                         // as we only accept version 1 (min/max values)
 136
 137                         if (IsUnrestricted (e)) {
 138                                 flags = SecurityPermissionFlag.AllFlags;
 139                         }
 140                         else {
 141                                 string f = e.Attribute ("Flags");
 142                                 if (f == null) {
 143                                         flags = SecurityPermissionFlag.NoFlags;
 144                                 }
 145                                 else {
 146                                         flags = (SecurityPermissionFlag) Enum.Parse (
 147                                                 typeof (SecurityPermissionFlag), f);
 148                                 }
 149                         }
 150                 }
 151
 152                 public override SecurityElement ToXml ()
 153                 {
 154                         SecurityElement e = Element (version);
 155                         if (IsUnrestricted ())
 156                                 e.AddAttribute ("Unrestricted", "true");
 157                         else
 158                                 e.AddAttribute ("Flags", flags.ToString ());
 159                         return e;
 160                 }
 161
 162                 // IBuiltInPermission
 163                 int IBuiltInPermission.GetTokenIndex ()
 164                 {
 165                         return (int) BuiltInToken.Security;
 166                 }
 167
 168                 // helpers
 169
 170                 private bool IsEmpty ()
 171                 {
 172                         return (flags == SecurityPermissionFlag.NoFlags);
 173                 }
 174
 175                 private SecurityPermission Cast (IPermission target)
 176                 {
 177                         if (target == null)
 178                                 return null;
 179
 180                         SecurityPermission sp = (target as SecurityPermission);
 181                         if (sp == null) {
 182                                 ThrowInvalidPermission (target, typeof (SecurityPermission));
 183                         }
 184
 185                         return sp;
 186                 }
 187         }
 188 }