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//---------------------------------------------------------------------------
//
// <copyright file="ReturnEventSaver.cs" company="Microsoft">
// Copyright (C) Microsoft Corporation. All rights reserved.
// </copyright>
//
// Description:
// This class provides a convenient way to persist/depersist the events on a PageFunction
//
// By calling the _Detach() method on a pagefunction,
// this class will build a list of the class & methods on that Pagefunction,
// as well as removing the current listener on the class when it's done.
//
// By passing in a pagefunction on the _Attach method, the class will reattach the
// saved list to the calling pagefunction
//
// History:
// 06/11/03: marka created
//
//---------------------------------------------------------------------------
using System;
using System.Windows.Navigation;
using System.Windows;
using System.Diagnostics;
using System.Collections;
using System.Reflection;
using System.IO;
using System.Security.Permissions;
using System.Security;
namespace MS.Internal.AppModel
{
[Serializable]
internal struct ReturnEventSaverInfo
{
internal ReturnEventSaverInfo(string delegateTypeName, string targetTypeName, string delegateMethodName, bool fSamePf)
{
_delegateTypeName = delegateTypeName;
_targetTypeName = targetTypeName;
_delegateMethodName = delegateMethodName;
_delegateInSamePF = fSamePf;
}
internal String _delegateTypeName;
internal String _targetTypeName;
internal String _delegateMethodName;
internal bool _delegateInSamePF; // Return Event handler comes from the same pagefunction, this is for non-generic workaround.
}
[Serializable]
internal class ReturnEventSaver
{
internal ReturnEventSaver()
{
}
/// <SecurityNote>
/// Critical - sets the critical _returnList.
/// TreatAsSafe - _returnList is not exposed in any way.
/// </SecurityNote>
[SecurityCritical, SecurityTreatAsSafe]
internal void _Detach(PageFunctionBase pf)
{
if (pf._Return != null && pf._Saver == null)
{
ReturnEventSaverInfo[] list = null;
Delegate[] delegates = null;
delegates = (pf._Return).GetInvocationList();
list = _returnList = new ReturnEventSaverInfo[delegates.Length];
for (int i = 0; i < delegates.Length; i++)
{
Delegate returnDelegate = delegates[i];
bool bSamePf = false;
if (returnDelegate.Target == pf)
{
// This is the Event Handler implemented by the same PF, use for NonGeneric handling.
bSamePf = true;
}
MethodInfo m = returnDelegate.Method;
ReturnEventSaverInfo info = new ReturnEventSaverInfo(
returnDelegate.GetType().AssemblyQualifiedName,
returnDelegate.Target.GetType().AssemblyQualifiedName,
m.Name, bSamePf);
list[i] = info;
}
//
// only save if there were delegates already attached.
// note that there will be cases where the Saver has already been pre-populated from a Load
// but no delegates have been created yet ( as the PF hasn`t called finish as yet)
//
// By only storing the saver once there are delegates - we avoid the problem of
// wiping out any newly restored saver
pf._Saver = this;
}
pf._DetachEvents();
}
//
// Attach the stored events to the supplied pagefunction.
//
// caller - the Calling Page's root element. We will reattach events *from* this page root element *to* the child
//
// child - the child PageFunction. Caller was originally attached to child, we're now reattaching *to* the child
//
/// <SecurityNote>
/// Critical - Asserts ReflectionPermission to be able re-create delegate to private method.
/// TreatAsSafe - The delegate created is identical to the one that _Detach() received from
/// the application and saved. This is ensured by matching the type of the original target
/// object against the type of the new target. Thus we know that the application was able
/// to create a delegate over the exact method, and even if that method had a LinkDemand,
/// it was satisfied by the application.
/// </SecurityNote>
[SecurityCritical, SecurityTreatAsSafe]
internal void _Attach(Object caller, PageFunctionBase child)
{
ReturnEventSaverInfo[] list = null;
list = _returnList;
if (list != null)
{
Debug.Assert(caller != null, "Caller should not be null");
for (int i = 0; i < list.Length; i++)
{
//
//
if (string.Compare(_returnList[i]._targetTypeName, caller.GetType().AssemblyQualifiedName, StringComparison.Ordinal) != 0)
{
throw new NotSupportedException(SR.Get(SRID.ReturnEventHandlerMustBeOnParentPage));
}
Delegate d;
try
{
new ReflectionPermission(ReflectionPermissionFlag.MemberAccess).Assert(); // BlessedAssert
d = Delegate.CreateDelegate(
Type.GetType(_returnList[i]._delegateTypeName),
caller,
_returnList[i]._delegateMethodName);
}
catch (Exception ex)
{
throw new NotSupportedException(SR.Get(SRID.ReturnEventHandlerMustBeOnParentPage), ex);
}
finally
{
ReflectionPermission.RevertAssert();
}
child._AddEventHandler(d);
}
}
}
/// <SecurityNote>
/// Critical: contains metadata for delegates created under elevation.
/// </SecurityNote>
[SecurityCritical]
private ReturnEventSaverInfo[] _returnList; // The list of delegates we want to persist and return later
}
}
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