class/corlib/System.Security.Permissions/HostProtectionPermission.cs

   1 //
   2 // System.Security.Permissions.HostProtectionPermission.cs
   3 //
   4 // Author:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //
   7 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System.Globalization;
  30
  31 namespace System.Security.Permissions {
  32
  33         [Serializable]
  34         internal sealed class HostProtectionPermission : CodeAccessPermission, IUnrestrictedPermission, IBuiltInPermission {
  35
  36                 private const int version = 1;
  37
  38                 private HostProtectionResource _resources;
  39
  40                 // constructors
  41
  42                 public HostProtectionPermission (PermissionState state)
  43                 {
  44                         if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
  45                                 _resources = HostProtectionResource.All;
  46                         else
  47                                 _resources = HostProtectionResource.None;
  48                 }
  49
  50                 public HostProtectionPermission (HostProtectionResource resources)
  51                 {
  52                         // reuse validation by the Flags property
  53                         Resources = _resources;
  54                 }
  55
  56                 public HostProtectionResource Resources {
  57                         get { return _resources; }
  58                         set {
  59                                 if (!Enum.IsDefined (typeof (HostProtectionResource), value)) {
  60                                         string msg = String.Format (Locale.GetText ("Invalid enum {0}"), value);
  61                                         throw new ArgumentException (msg, "HostProtectionResource");
  62                                 }
  63                                 _resources = value;
  64                         }
  65                 }
  66
  67                 public override IPermission Copy ()
  68                 {
  69                         return new HostProtectionPermission (_resources);
  70                 }
  71
  72                 public override IPermission Intersect (IPermission target)
  73                 {
  74                         HostProtectionPermission hpp = Cast (target);
  75                         if (hpp == null)
  76                                 return null;
  77
  78                         if (this.IsUnrestricted () && hpp.IsUnrestricted ())
  79                                 return new HostProtectionPermission (PermissionState.Unrestricted);
  80                         if (this.IsUnrestricted ())
  81                                 return hpp.Copy ();
  82                         if (hpp.IsUnrestricted ())
  83                                 return this.Copy ();
  84                         return new HostProtectionPermission (_resources & hpp._resources);
  85                 }
  86
  87                 public override IPermission Union (IPermission target)
  88                 {
  89                         HostProtectionPermission hpp = Cast (target);
  90                         if (hpp == null)
  91                                 return this.Copy ();
  92
  93                         if (this.IsUnrestricted () || hpp.IsUnrestricted ())
  94                                 return new HostProtectionPermission (PermissionState.Unrestricted);
  95
  96                         return new HostProtectionPermission (_resources | hpp._resources);
  97                 }
  98
  99                 public override bool IsSubsetOf (IPermission target)
 100                 {
 101                         HostProtectionPermission hpp = Cast (target);
 102                         if (hpp == null)
 103                                 return (_resources == HostProtectionResource.None);
 104
 105                         if (hpp.IsUnrestricted ())
 106                                 return true;
 107                         if (this.IsUnrestricted ())
 108                                 return false;
 109
 110                         return ((_resources & ~hpp._resources) == 0);
 111                 }
 112
 113                 public override void FromXml (SecurityElement e)
 114                 {
 115                         // General validation in CodeAccessPermission
 116                         CheckSecurityElement (e, "e", version, version);
 117                         // Note: we do not (yet) care about the return value
 118                         // as we only accept version 1 (min/max values)
 119
 120                         _resources = (HostProtectionResource) Enum.Parse (
 121                                 typeof (HostProtectionResource), e.Attribute ("Resources"));
 122                 }
 123
 124                 public override SecurityElement ToXml ()
 125                 {
 126                         SecurityElement e = Element (version);
 127                         e.AddAttribute ("Resources", _resources.ToString ());
 128                         return e;
 129                 }
 130
 131                 // IUnrestrictedPermission
 132                 public bool IsUnrestricted ()
 133                 {
 134                         return (_resources == HostProtectionResource.All);
 135                 }
 136
 137                 // IBuiltInPermission
 138                 int IBuiltInPermission.GetTokenIndex ()
 139                 {
 140                         return (int) BuiltInToken.HostProtection;
 141                 }
 142
 143                 // helpers
 144
 145                 private HostProtectionPermission Cast (IPermission target)
 146                 {
 147                         if (target == null)
 148                                 return null;
 149
 150                         HostProtectionPermission hpp = (target as HostProtectionPermission);
 151                         if (hpp == null) {
 152                                 ThrowInvalidPermission (target, typeof (HostProtectionPermission));
 153                         }
 154
 155                         return hpp;
 156                 }
 157         }
 158 }
 159