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//------------------------------------------------------------------------------
// <copyright file="ExecutionContextUtil.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Util {
using System;
using System.Reflection;
using System.Security.Permissions;
using System.Threading;
// This class contains utility methods for dealing with security contexts when crossing AppDomain boundaries.
[SecurityPermission(SecurityAction.LinkDemand, Unrestricted = true)]
internal static class ExecutionContextUtil {
private static readonly ContextCallback s_actionToActionObjShunt = obj => ((Action)obj)();
private static readonly ExecutionContext s_dummyDefaultEC = GetDummyDefaultEC();
[ReflectionPermission(SecurityAction.Assert, MemberAccess = true)]
private static ExecutionContext GetDummyDefaultEC() {
// The ExecutionContext.PreAllocatedDefault property is special-cased by ExecutionContext to be a blank context and to allow multiple invocation.
PropertyInfo propInfo = typeof(ExecutionContext).GetProperty("PreAllocatedDefault", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
if (propInfo == null) {
throw new Exception(SR.GetString(SR.Type_doesnt_have_property, typeof(ExecutionContext).FullName, "PreAllocatedDefault"));
}
return (ExecutionContext) propInfo.GetValue(null, null);
}
// Removes all context associated with the current thread (call context, IPrincipal, etc.) and invokes the provided callback.
// The intent of this method is to get any user-provided context off the current thread before crossing an AppDomain boundary,
// as the existence of that context could lead to behavioral problems (see DevDiv #205764) or security problems (see DevDiv #206598).
internal static void RunInNullExecutionContext(Action callback) {
ExecutionContext.Run(s_dummyDefaultEC, s_actionToActionObjShunt, callback);
}
}
}
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