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         [ComVisible (true)]
  38         [Serializable]
  39         public sealed class SecurityPermission :
  40                 CodeAccessPermission, IUnrestrictedPermission, IBuiltInPermission {
  41
  42                 private const int version = 1;
  43
  44                 private SecurityPermissionFlag flags;
  45
  46                 // constructors
  47
  48                 public SecurityPermission (PermissionState state)
  49                 {
  50                         if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
  51                                 flags = SecurityPermissionFlag.AllFlags;
  52                         else
  53                                 flags = SecurityPermissionFlag.NoFlags;
  54                 }
  55
  56                 public SecurityPermission (SecurityPermissionFlag flag)
  57                 {
  58                         // reuse validation by the Flags property
  59                         Flags = flag;
  60                 }
  61
  62                 public SecurityPermissionFlag Flags {
  63                         get { return flags; }
  64                         set {
  65                                 if ((value & SecurityPermissionFlag.AllFlags) != value) {
  66                                         string msg = String.Format (Locale.GetText ("Invalid flags {0}"), value);
  67                                         throw new ArgumentException (msg, "SecurityPermissionFlag");
  68                                 }
  69                                 flags = value;
  70                         }
  71                 }
  72
  73                 // IUnrestrictedPermission
  74                 public bool IsUnrestricted ()
  75                 {
  76                         return (flags == SecurityPermissionFlag.AllFlags);
  77                 }
  78
  79                 public override IPermission Copy ()
  80                 {
  81                         return new SecurityPermission (flags);
  82                 }
  83
  84                 public override IPermission Intersect (IPermission target)
  85                 {
  86                         SecurityPermission sp = Cast (target);
  87                         if (sp == null)
  88                                 return null;
  89                         if (IsEmpty () || sp.IsEmpty ())
  90                                 return null;
  91
  92                         if (this.IsUnrestricted () && sp.IsUnrestricted ())
  93                                 return new SecurityPermission (PermissionState.Unrestricted);
  94                         if (this.IsUnrestricted ())
  95                                 return sp.Copy ();
  96                         if (sp.IsUnrestricted ())
  97                                 return this.Copy ();
  98
  99                         SecurityPermissionFlag f = flags & sp.flags;
 100                         if (f == SecurityPermissionFlag.NoFlags)
 101                                 return null;
 102                         else
 103                                 return new SecurityPermission (f);
 104                 }
 105
 106                 public override IPermission Union (IPermission target)
 107                 {
 108                         SecurityPermission sp = Cast (target);
 109                         if (sp == null)
 110                                 return this.Copy ();
 111
 112                         if (this.IsUnrestricted () || sp.IsUnrestricted ())
 113                                 return new SecurityPermission (PermissionState.Unrestricted);
 114
 115                         return new SecurityPermission (flags | sp.flags);
 116                 }
 117
 118                 public override bool IsSubsetOf (IPermission target)
 119                 {
 120                         SecurityPermission sp = Cast (target);
 121                         if (sp == null)
 122                                 return IsEmpty ();
 123
 124                         if (sp.IsUnrestricted ())
 125                                 return true;
 126                         if (this.IsUnrestricted ())
 127                                 return false;
 128
 129                         return ((flags & ~sp.flags) == 0);
 130                 }
 131
 132                 public override void FromXml (SecurityElement esd)
 133                 {
 134                         // General validation in CodeAccessPermission
 135                         CheckSecurityElement (esd, "esd", version, version);
 136                         // Note: we do not (yet) care about the return value
 137                         // as we only accept version 1 (min/max values)
 138
 139                         if (IsUnrestricted (esd)) {
 140                                 flags = SecurityPermissionFlag.AllFlags;
 141                         }
 142                         else {
 143                                 string f = esd.Attribute ("Flags");
 144                                 if (f == null) {
 145                                         flags = SecurityPermissionFlag.NoFlags;
 146                                 }
 147                                 else {
 148                                         flags = (SecurityPermissionFlag) Enum.Parse (
 149                                                 typeof (SecurityPermissionFlag), f);
 150                                 }
 151                         }
 152                 }
 153
 154                 public override SecurityElement ToXml ()
 155                 {
 156                         SecurityElement e = Element (version);
 157                         if (IsUnrestricted ())
 158                                 e.AddAttribute ("Unrestricted", "true");
 159                         else
 160                                 e.AddAttribute ("Flags", flags.ToString ());
 161                         return e;
 162                 }
 163
 164                 // IBuiltInPermission
 165                 int IBuiltInPermission.GetTokenIndex ()
 166                 {
 167                         return (int) BuiltInToken.Security;
 168                 }
 169
 170                 // helpers
 171
 172                 private bool IsEmpty ()
 173                 {
 174                         return (flags == SecurityPermissionFlag.NoFlags);
 175                 }
 176
 177                 private SecurityPermission Cast (IPermission target)
 178                 {
 179                         if (target == null)
 180                                 return null;
 181
 182                         SecurityPermission sp = (target as SecurityPermission);
 183                         if (sp == null) {
 184                                 ThrowInvalidPermission (target, typeof (SecurityPermission));
 185                         }
 186
 187                         return sp;
 188                 }
 189         }
 190 }