HostProtectionPermission.cs :  » 2.6.4-mono-.net-core » System.Security » System » Security » Permissions » C# / CSharp Open Source

//
// System.Security.Permissions.HostProtectionPermission.cs
//
// Author:
//  Sebastien Pouliot  <sebastien@ximian.com>
//
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System.Globalization;

namespace System.Security.Permissions{
  
  [Serializable]
  internal sealed class HostProtectionPermission : CodeAccessPermission, IUnrestrictedPermission, IBuiltInPermission {

    private const int version = 1;

    private HostProtectionResource _resources;

    // constructors

    public HostProtectionPermission (PermissionState state)
    {
      if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
        _resources = HostProtectionResource.All;
      else
        _resources = HostProtectionResource.None;
    }

    public HostProtectionPermission (HostProtectionResource resources) 
    {
      // reuse validation by the Flags property
      Resources = _resources;
    }

    public HostProtectionResource Resources {
      get { return _resources; }
      set {
        if (!Enum.IsDefined (typeof (HostProtectionResource), value)) {
          string msg = String.Format (Locale.GetText ("Invalid enum {0}"), value);
          throw new ArgumentException (msg, "HostProtectionResource");
        }
        _resources = value;
      }
    }

    public override IPermission Copy () 
    {
      return new HostProtectionPermission (_resources);
    }

    public override IPermission Intersect (IPermission target) 
    {
      HostProtectionPermission hpp = Cast (target);
      if (hpp == null)
        return null;

      if (this.IsUnrestricted () && hpp.IsUnrestricted ())
        return new HostProtectionPermission (PermissionState.Unrestricted);
      if (this.IsUnrestricted ())
        return hpp.Copy ();
      if (hpp.IsUnrestricted ())
        return this.Copy ();
      return new HostProtectionPermission (_resources & hpp._resources);
    }

    public override IPermission Union (IPermission target) 
    {
      HostProtectionPermission hpp = Cast (target);
      if (hpp == null)
        return this.Copy ();

      if (this.IsUnrestricted () || hpp.IsUnrestricted ())
        return new HostProtectionPermission (PermissionState.Unrestricted);
      
      return new HostProtectionPermission (_resources | hpp._resources);
    }

    public override bool IsSubsetOf (IPermission target) 
    {
      HostProtectionPermission hpp = Cast (target);
      if (hpp == null) 
        return (_resources == HostProtectionResource.None);

      if (hpp.IsUnrestricted ())
        return true;
      if (this.IsUnrestricted ())
        return false;

      return ((_resources & ~hpp._resources) == 0);
    }

    public override void FromXml (SecurityElement e) 
    {
      // General validation in CodeAccessPermission
      CheckSecurityElement (e, "e", version, version);
      // Note: we do not (yet) care about the return value 
      // as we only accept version 1 (min/max values)

      _resources = (HostProtectionResource) Enum.Parse (
        typeof (HostProtectionResource), e.Attribute ("Resources"));
    }

    public override SecurityElement ToXml () 
    {
      SecurityElement e = Element (version);
      e.AddAttribute ("Resources", _resources.ToString ());
      return e;
    }

    // IUnrestrictedPermission
    public bool IsUnrestricted () 
    {
      return (_resources == HostProtectionResource.All);
    }

    // IBuiltInPermission
    int IBuiltInPermission.GetTokenIndex ()
    {
      return (int) BuiltInToken.HostProtection;
    }

    // helpers

    private HostProtectionPermission Cast (IPermission target)
    {
      if (target == null)
        return null;

      HostProtectionPermission hpp = (target as HostProtectionPermission);
      if (hpp == null) {
        ThrowInvalidPermission (target, typeof (HostProtectionPermission));
      }

      return hpp;
    }
  }
}