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

//
// System.Security.Permissions.SecurityPermission.cs
//
// Authors:
//  Dan Lewis (dihlewis@yahoo.co.uk)
//  Sebastien Pouliot  <sebastien@ximian.com>
//
// (C) 2002
// Portions (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2005 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;
using System.Runtime.InteropServices;

namespace System.Security.Permissions{

  [ComVisible (true)]
  [Serializable]
  public sealed class SecurityPermission :
    CodeAccessPermission, IUnrestrictedPermission, IBuiltInPermission {

    private const int version = 1;

    private SecurityPermissionFlag flags;

    // constructors

    public SecurityPermission (PermissionState state)
    {
      if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
        flags = SecurityPermissionFlag.AllFlags;
      else
        flags = SecurityPermissionFlag.NoFlags;
    }

    public SecurityPermission (SecurityPermissionFlag flag) 
    {
      // reuse validation by the Flags property
      Flags = flag;
    }

    public SecurityPermissionFlag Flags {
      get { return flags; }
      set {
        if ((value & SecurityPermissionFlag.AllFlags) != value) {
          string msg = String.Format (Locale.GetText ("Invalid flags {0}"), value);
          throw new ArgumentException (msg, "SecurityPermissionFlag");
        }
        flags = value;
      }
    }

    // IUnrestrictedPermission
    public bool IsUnrestricted () 
    {
      return (flags == SecurityPermissionFlag.AllFlags);
    }

    public override IPermission Copy () 
    {
      return new SecurityPermission (flags);
    }

    public override IPermission Intersect (IPermission target) 
    {
      SecurityPermission sp = Cast (target);
      if (sp == null)
        return null;
      if (IsEmpty () || sp.IsEmpty ())
        return null;

      if (this.IsUnrestricted () && sp.IsUnrestricted ())
        return new SecurityPermission (PermissionState.Unrestricted);
      if (this.IsUnrestricted ())
        return sp.Copy ();
      if (sp.IsUnrestricted ())
        return this.Copy ();

      SecurityPermissionFlag f = flags & sp.flags;
      if (f == SecurityPermissionFlag.NoFlags)
        return null;
      else
        return new SecurityPermission (f);
    }

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

      if (this.IsUnrestricted () || sp.IsUnrestricted ())
        return new SecurityPermission (PermissionState.Unrestricted);
      
      return new SecurityPermission (flags | sp.flags);
    }

    public override bool IsSubsetOf (IPermission target) 
    {
      SecurityPermission sp = Cast (target);
      if (sp == null) 
        return IsEmpty ();

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

      return ((flags & ~sp.flags) == 0);
    }

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

      if (IsUnrestricted (esd)) {
        flags = SecurityPermissionFlag.AllFlags;
      }
      else {
        string f = esd.Attribute ("Flags");
        if (f == null) {
          flags = SecurityPermissionFlag.NoFlags;
        }
        else {
          flags = (SecurityPermissionFlag) Enum.Parse (
            typeof (SecurityPermissionFlag), f);
        }
      }
    }

    public override SecurityElement ToXml () 
    {
      SecurityElement e = Element (version);
      if (IsUnrestricted ())
        e.AddAttribute ("Unrestricted", "true");
      else
        e.AddAttribute ("Flags", flags.ToString ());
      return e;
    }

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

    // helpers

    private bool IsEmpty ()
    {
      return (flags == SecurityPermissionFlag.NoFlags);
    }

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

      SecurityPermission sp = (target as SecurityPermission);
      if (sp == null) {
        ThrowInvalidPermission (target, typeof (SecurityPermission));
      }

      return sp;
    }
  }
}