Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media / EventProxy.cs / 1305600 / EventProxy.cs
//------------------------------------------------------------------------------ // Microsoft Avalon // Copyright (c) Microsoft Corporation, 2003 // // File: eventproxy.cs //----------------------------------------------------------------------------- #pragma warning disable 1634, 1691 // Allow suppression of certain presharp messages using System.Windows.Media; using System; using MS.Internal; using MS.Win32; using System.Reflection; using System.Collections; using System.Diagnostics; using System.Security; using System.Security.Permissions; using System.Runtime.InteropServices; using Microsoft.Internal; using MS.Internal.PresentationCore; // TODOTODO Make our own namespace for internal stuff. namespace System.Windows.Media { #region EventProxyDescriptor [StructLayout(LayoutKind.Sequential)] internal struct EventProxyDescriptor { internal delegate void Dispose( ref EventProxyDescriptor pEPD ); internal delegate int RaiseEvent( ref EventProxyDescriptor pEPD, [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 2)] byte[] buffer, uint cb ); internal Dispose pfnDispose; internal RaiseEvent pfnRaiseEvent; ////// Critical: calls GCHandle.get_Target which LinkDemands /// TreatAsSafe: can't pass in an arbitrary class, only EventProxyDescriptor. Also, it's OK to dispose this. /// [SecurityCritical, SecurityTreatAsSafe] internal static void StaticDispose(ref EventProxyDescriptor pEPD) { Debug.Assert(((IntPtr)pEPD.m_handle) != IntPtr.Zero, "If this asserts fires: Why is it firing? It might be legal in future."); EventProxyWrapper epw = (EventProxyWrapper)(pEPD.m_handle.Target); ((System.Runtime.InteropServices.GCHandle)(pEPD.m_handle)).Free(); } internal System.Runtime.InteropServices.GCHandle m_handle; } #endregion #region EventProxyStaticPtrs ////// We need to keep the delegates alive. /// internal static class EventProxyStaticPtrs { static EventProxyStaticPtrs() { EventProxyStaticPtrs.pfnDispose = new EventProxyDescriptor.Dispose(EventProxyDescriptor.StaticDispose); EventProxyStaticPtrs.pfnRaiseEvent = new EventProxyDescriptor.RaiseEvent(EventProxyWrapper.RaiseEvent); } internal static EventProxyDescriptor.Dispose pfnDispose; internal static EventProxyDescriptor.RaiseEvent pfnRaiseEvent; } #endregion #region EventProxyWrapper ////// Event proxy wrapper will relay events from unmanaged code to managed code /// internal class EventProxyWrapper { private WeakReference target; #region Constructor private EventProxyWrapper(IInvokable invokable) { target = new WeakReference(invokable); } #endregion #region Verify private void Verify() { if (target == null) { throw new System.ObjectDisposedException("EventProxyWrapper"); } } #endregion #region Public methods ////// Critical: calls Marshal.GetHRForException which LinkDemands /// TreatAsSafe: ok to return an hresult in partial trust /// [SecurityCritical, SecurityTreatAsSafe] public int RaiseEvent(byte[] buffer, uint cb) { #pragma warning disable 6500 try { Verify(); IInvokable invokable = (IInvokable)target.Target; if (invokable != null) { invokable.RaiseEvent(buffer, (int)cb); } else { // return E_HANDLE to notify that object is no longer alive return NativeMethods.E_HANDLE; } } catch (Exception e) { return Marshal.GetHRForException(e); } #pragma warning restore 6500 return NativeMethods.S_OK; } #endregion #region Delegate Implemetations ////// Critical: This code calls into handle to get Target which has a link demand /// TreatAsSafe: EventProxyWrapper is safe to expose /// [SecurityCritical,SecurityTreatAsSafe] internal static EventProxyWrapper FromEPD(ref EventProxyDescriptor epd) { Debug.Assert(((IntPtr)epd.m_handle) != IntPtr.Zero, "Stream is disposed."); System.Runtime.InteropServices.GCHandle handle = (System.Runtime.InteropServices.GCHandle)(epd.m_handle); return (EventProxyWrapper)(handle.Target); } internal static int RaiseEvent(ref EventProxyDescriptor pEPD, byte[] buffer, uint cb) { EventProxyWrapper target = EventProxyWrapper.FromEPD(ref pEPD); if (target != null) { return target.RaiseEvent(buffer, cb); } else { return NativeMethods.E_HANDLE; } } #endregion #region Static Create Method(s) ////// Critical: This code hooks up event sinks for unmanaged events /// It also calls into a native method via MILCreateEventProxy /// [SecurityCritical] internal static SafeMILHandle CreateEventProxyWrapper(IInvokable invokable) { if (invokable == null) { throw new System.ArgumentNullException("invokable"); } SafeMILHandle eventProxy = null; EventProxyWrapper epw = new EventProxyWrapper(invokable); EventProxyDescriptor epd = new EventProxyDescriptor(); epd.pfnDispose = EventProxyStaticPtrs.pfnDispose; epd.pfnRaiseEvent = EventProxyStaticPtrs.pfnRaiseEvent; epd.m_handle = System.Runtime.InteropServices.GCHandle.Alloc(epw, System.Runtime.InteropServices.GCHandleType.Normal); HRESULT.Check(MILCreateEventProxy(ref epd, out eventProxy)); return eventProxy; } #endregion ////// Critical: Elevates to unmanaged code permission /// [SuppressUnmanagedCodeSecurity] [SecurityCritical] [DllImport(DllImport.MilCore)] private extern static int /* HRESULT */ MILCreateEventProxy(ref EventProxyDescriptor pEPD, out SafeMILHandle ppEventProxy); } #endregion } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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