Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / Orcas / NetFXw7 / wpf / src / Shared / MS / Win32 / HwndSubclass.cs / 1 / HwndSubclass.cs
using System;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using MS.Internal;
using MS.Utility;
using System.Windows;
using System.Windows.Threading;
using System.Security; // CAS
using System.Threading; // Thread
// The SecurityHelper class differs between assemblies and could not actually be
// shared, so it is duplicated across namespaces to prevent name collision.
#if WINDOWS_BASE
using MS.Internal.WindowsBase;
#elif PRESENTATION_CORE
using MS.Internal.PresentationCore;
#elif PRESENTATIONFRAMEWORK
using MS.Internal.PresentationFramework;
#elif DRT
using MS.Internal.Drt;
#else
#error Attempt to use a class (duplicated across multiple namespaces) from an unknown assembly.
#endif
namespace MS.Win32
{
///
/// The HwndSubclass class provides a managed way to subclass an existing
/// HWND. This class inserts itself into the WNDPROC chain for the
/// window, and will call a specified delegate to process the window
/// messages that arrive. The delegate has a slightly different
/// signature than a WNDPROC to be more specific about whether the
/// message was handled or not. If the message was not handled by the
/// delegate, this class passes the message on down the WNDPROC chain.
///
/// To use this class properly, simply:
/// 1) Create an instance of the HwndSubclass class and pass the delegate
/// to the constructor.
/// 2) Call Attach(HWND) to subclass an existing window.
/// 3) Call Detach(false) to unsubclass the window when you are done.
///
/// You can also just call RequestDetach() to send a message to the
/// window that will cause the HwndSubclass to detach itself. This is
/// important if you are on a different thread, as the HwndSubclass class
/// is not thread safe and will be operated on by the thread that owns
/// the window.
///
/// Not available to partial trust callers
[FriendAccessAllowed] // Built into Base, also used by Framework
internal class HwndSubclass : IDisposable
{
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
static HwndSubclass()
{
DetachMessage = UnsafeNativeMethods.RegisterWindowMessage("HwndSubclass.DetachMessage");
if (DetachMessage == 0)
{
throw new System.ComponentModel.Win32Exception();
}
// Go find the address of DefWindowProc.
IntPtr hModuleUser32 = UnsafeNativeMethods.GetModuleHandle(ExternDll.User32);
IntPtr address = UnsafeNativeMethods.GetProcAddress(new HandleRef(null,hModuleUser32), "DefWindowProcW");
DefWndProc = address;
}
///
/// This HwndSubclass constructor binds the HwndSubclass object to the
/// specified delegate. This delegate will be called to process
/// the messages that are sent or posted to the window.
///
///
/// The delegate that will be called to process the messages that
/// are sent or posted to the window.
///
///
/// Nothing.
///
///
/// Critical: This code creates an object that is not allowed in partial trust
///
[SecurityCritical]
internal HwndSubclass(HwndWrapperHook hook)
{
if(hook == null)
{
throw new ArgumentNullException("hook");
}
_bond = Bond.Unattached;
_hook = new WeakReference(hook);
// Allocate a GC handle so that we won't be collected, even if all
// references to us get released. This is because a component outside
// of the managed code (ie. the window we are subclassing) still holds
// a reference to us - just not a reference that the GC recognizes.
_gcHandle = GCHandle.Alloc(this);
}
// This is LIVE OBJECT because it has a GCHandle. The only time LIVE OBJECTS
// are destroyed is during Shutdown. But Shutdown cleanup is handled through
// the ManagedWndProcTracker and hence no work needs to happen here. PLEASE
// NOTE that reintroducing any cleanup logic in here will conflict with the cleanup
// logic in ManagedWndProcTracker and hence must be avoided. If this instance
// has been disposed its GCHandle is released at the time and hence this object
// is available for GC thereafter. Even in that case since all the cleanup has been
// done during dispose there is no further cleanup required.
// ///
// /// Critical - It calls the critical DisposeImpl.
// ///
// [SecurityCritical]
// ~HwndSubclass()
// {
// // In Shutdown, the finalizer is called on LIVE OBJECTS.
// //
// // So this method can be called. (even though we are pinned)
// // If it is, we're shutting down so it's OK to force unhooking
// // the subclass.
// DisposeImpl(true);
// }
///
/// Critical - It calls the critical DisposeImpl.
/// PublicOK - Demands for AllWindows permission.
///
[SecurityCritical]
public virtual void Dispose()
{
SecurityHelper.DemandUIWindowPermission();
DisposeImpl(false);
}
///
/// Critical - Calls the critical UnhookWindowProc.
///
[SecurityCritical]
private bool DisposeImpl(bool forceUnhook)
{
_hook = null;
return UnhookWindowProc(forceUnhook);
}
///
/// This method subclasses the specified window, such that the
/// delegate specified to the constructor will be called to process
/// the messages that are sent or posted to this window.
///
///
/// The window to subclass.
///
///
/// An identifier that can be used to reference this instance of
/// the HwndSubclass class in the static RequestDetach method.
///
///
/// Critical - It calls CriticalAttach.
/// TreatAsSafe - Demands for AllWindows permission.
///
[SecurityCritical, SecurityTreatAsSafe]
internal IntPtr Attach(IntPtr hwnd)
{
SecurityHelper.DemandUIWindowPermission();
if (_bond != Bond.Unattached)
throw new InvalidOperationException(SR.Get(SRID.HwndSubclassMultipleAttach));
return CriticalAttach( hwnd ) ;
}
///
/// This method unsubclasses this HwndSubclass object from the window
/// it previously subclassed. The HwndSubclass object is not thread
/// safe, and should thus be called only by the thread that owns
/// the window being unsubclassed.
///
///
/// Whether or not the unsubclassing should be forced. Due to the
/// way that Win32 implements window subclassing, it is not always
/// possible to safely remove a window proc from the WNDPROC chain.
/// However, the delegate will not be called again after this
/// method returns.
///
///
/// Whether or not this HwndSubclass object was actually removed from
/// the WNDPROC chain.
///
///
/// TreatAsSafe: Demands for all windows
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
internal bool Detach(bool force)
{
SecurityHelper.DemandUIWindowPermission();
return CriticalDetach(force);
}
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
internal bool CriticalDetach(bool force)
{
bool detached;
// If we have already detached, return immediately.
if(_bond == Bond.Detached || _bond == Bond.Unattached)
{
detached = true;
}
else
{
// When we detach, we simply make a note of it.
_bond = Bond.Orphaned;
// try to unhook the subclass
detached = DisposeImpl(force);
}
return detached;
}
///
/// This method sends a message to the window that is currently
/// subclassed by this instance of the HwndSubclass class, in order
/// to unsubclass the window. This is important if a different
/// thread than the thread that owns the window wants to initiate
/// the unsubclassing.
///
///
/// Whether or not the unsubclassing should be forced. Due to the
/// way that Win32 implements window subclassing, it is not always
/// possible to safely remove a window proc from the WNDPROC chain.
/// However, the delegate will not be called again after this
/// method returns.
///
///
/// Nothing.
///
///
/// Critical - Probes _hwndAttached for value.
/// TreatAsSafe - The RequestDetach overload we're calling is public and safe (demands UIWindowPermission).
///
[SecurityCritical, SecurityTreatAsSafe]
internal void RequestDetach(bool force)
{
// Let the static version do the work.
if(_hwndAttached != IntPtr.Zero)
{
RequestDetach(_hwndAttached, (IntPtr) _gcHandle, force);
}
}
///
/// This method sends a message to the specified window in order to
/// cause the specified bridge to unsubclass the window. This is
/// important if a different thread than the thread that owns the
/// window wants to initiate the unsubclassing. The HwndSubclass
/// object must be identified by the value returned from Attach().
///
///
/// The window to unsubclass.
///
///
/// The identifier of the subclass to unsubclass.
///
///
/// Whether or not the unsubclassing should be forced. Due to the
/// way that Win32 implements window subclassing, it is not always
/// possible to safely remove a window proc from the WNDPROC chain.
/// However, the delegate will not be called again after this
/// method returns.
///
///
/// Nothing.
///
///
/// Critical - This touches the underlying windowing infrastructure; we may want to intercept windows-messages for security-related purposes in the future.
/// In general we restrict access to window handles.
/// TreatAsSafe - Demands UIWindowPermission.
///
[SecurityCritical, SecurityTreatAsSafe]
internal static void RequestDetach(IntPtr hwnd, IntPtr subclass, bool force)
{
SecurityHelper.DemandUIWindowPermission();
if(hwnd == IntPtr.Zero)
{
throw new ArgumentNullException("hwnd");
}
if(subclass == IntPtr.Zero)
{
throw new ArgumentNullException("subclass");
}
int iForce = force ? 1 : 0;
UnsafeNativeMethods.UnsafeSendMessage(hwnd, DetachMessage, subclass, (IntPtr) iForce);
}
///
/// This is the WNDPROC that gets inserted into the window's
/// WNDPROC chain. It responds to various conditions that
/// would cause this HwndSubclass object to unsubclass the window,
/// and then calls the delegate specified to the HwndSubclass
/// constructor to process the message. If the delegate does not
/// handle the message, the message is then passed on down the
/// WNDPROC chain for further processing.
///
///
/// The window that this message was sent or posted to.
///
///
/// The message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// The value that is the result of processing the message.
///
///
/// Critical: this function elevates via unsafe native method calls
///
[SecurityCritical]
internal IntPtr SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
{
IntPtr retval = IntPtr.Zero;
bool handled = false;
// If we are unattached and we receive a message, then we must have
// been used as the original window proc. In this case, we insert
// ourselves as if the original window proc had been DefWindowProc.
// We pass in DefWndProcStub as a workaround for a bug in UxTheme on
// Windows XP. For details see the comment on the DefWndProcWrapper method.
if(_bond == Bond.Unattached)
{
HookWindowProc(hwnd, new NativeMethods.WndProc(SubclassWndProc),
Marshal.GetFunctionPointerForDelegate(DefWndProcStub));
}
else if(_bond == Bond.Detached)
{
throw new InvalidOperationException();
}
IntPtr oldWndProc = _oldWndProc; // in case we get detached during this method
if(msg == DetachMessage)
{
// We received our special message to detach. Make sure it is intended
// for us by matching the bridge.
if(wParam == IntPtr.Zero || wParam == (IntPtr)_gcHandle)
{
int param = (int)lParam; // 0 - normal, 1 - force, 2 - force and forward
bool force = (param > 0);
retval = CriticalDetach(force) ? new IntPtr(1) : IntPtr.Zero ;
handled = (param < 2);
}
}
else
{
// Pass this message to our delegate function. Do this under
// the exception filter/handlers of the dispatcher for this thread.
Dispatcher dispatcher = Dispatcher.FromThread(Thread.CurrentThread);
if(dispatcher != null && !dispatcher.HasShutdownFinished)
{
if (_dispatcherOperationCallback == null)
_dispatcherOperationCallback = new DispatcherOperationCallback(this.DispatcherCallbackOperation);
// _paramDispatcherCallbackOperation is a thread static member which should be reused to avoid
// creating a new data structure every time we call DispatcherCallbackOperation
// Cache the param locally in case of reentrance and set _paramDispatcherCallbackOperation to null so reentrancy calls will create a new param
if (_paramDispatcherCallbackOperation == null)
_paramDispatcherCallbackOperation = new DispatcherOperationCallbackParameter();
DispatcherOperationCallbackParameter param = _paramDispatcherCallbackOperation;
_paramDispatcherCallbackOperation = null;
param.hwnd = hwnd;
param.msg = msg;
param.wParam = wParam;
param.lParam = lParam;
//synchronous call
object result = dispatcher.Invoke(
DispatcherPriority.Send,
_dispatcherOperationCallback,
param);
if (result != null)
{
handled = param.handled;
retval = param.retVal;
}
// Restore _paramDispatcherCallbackOperation to the previous value so we will reuse it on the next call
_paramDispatcherCallbackOperation = param;
}
// Handle WM_NCDESTROY explicitly to forcibly clean up.
if(msg == NativeMethods.WM_NCDESTROY)
{
// The fact that we received this message means that we are
// still in the call chain. This is our last chance to clean
// up, and no other message should be received by this window
// proc again. It is OK to force a cleanup now.
CriticalDetach(true);
// Always pass the WM_NCDESTROY message down the chain!
handled = false;
}
}
// If our window proc didn't handle this message, pass it on down the
// chain.
if(!handled)
{
retval = CallOldWindowProc(oldWndProc, hwnd, msg, wParam, lParam);
}
return retval;
}
// Perf bug: 1963989
// _paramDispatcherCallbackOperation is a thread static member which should be reused to avoid
// creating a new data structure every time we DispatcherCallbackOperation is called
// It also contains the return results (handled and retValue) from DispatcherCallbackOperation call
///
/// Critical: DispatcherOperationCallbackParameter contains hwnd, which is critical
///
[SecurityCritical]
[ThreadStatic]
private static DispatcherOperationCallbackParameter _paramDispatcherCallbackOperation;
// This class is used as a parameter and return result for DispatcherCallbackOperation call
private class DispatcherOperationCallbackParameter
{
internal IntPtr hwnd, wParam, lParam, retVal;
internal int msg;
internal bool handled;
}
private DispatcherOperationCallback _dispatcherOperationCallback = null;
///
/// Critical: it calls GetWindowLongPtr(), which is Critical
///
[ SecurityCritical ]
internal IntPtr CriticalAttach( IntPtr hwnd )
{
if(hwnd == IntPtr.Zero)
{
throw new ArgumentNullException("hwnd");
}
if(_bond != Bond.Unattached)
{
throw new InvalidOperationException();
}
NativeMethods.WndProc newWndProc = new NativeMethods.WndProc(SubclassWndProc);
IntPtr oldWndProc = UnsafeNativeMethods.GetWindowLongPtr(new HandleRef(this,hwnd), NativeMethods.GWL_WNDPROC);
HookWindowProc(hwnd, newWndProc, oldWndProc);
// Return the GC handle as a unique identifier of this
return (IntPtr) _gcHandle;
}
///
/// Critical: This code is a callback into the dispatcher. It is present
/// because under enforcements anonymous delagates throw a demand since
/// it becomes a transparent calling critical for this particular call
///
[SecurityCritical]
private object DispatcherCallbackOperation(object o)
{
DispatcherOperationCallbackParameter param = (DispatcherOperationCallbackParameter)o;
param.handled = false;
param.retVal = IntPtr.Zero;
if (_bond == Bond.Attached)
{
HwndWrapperHook hook= _hook.Target as HwndWrapperHook;
if (hook != null)
{
// make the call
param.retVal = hook(param.hwnd, param.msg, param.wParam, param.lParam, ref param.handled);
}
}
return param;
}
///
/// This method lets the user call the old WNDPROC, i.e
/// the next WNDPROC in the chain directly.
///
///
/// The WndProc to call.
///
///
/// The window that this message was sent or posted to.
///
///
/// The message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// The value that is the result of processing the message.
///
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
IntPtr CallOldWindowProc(IntPtr oldWndProc, IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam)
{
return UnsafeNativeMethods.CallWindowProc(oldWndProc, hwnd, msg, wParam, lParam);
}
///
/// Critical - it calls CriticalSetWindowLong()
///
[SecurityCritical]
private void HookWindowProc(IntPtr hwnd, NativeMethods.WndProc newWndProc, IntPtr oldWndProc)
{
_hwndAttached = hwnd;
_hwndHandleRef = new HandleRef(null,_hwndAttached);
_bond = Bond.Attached;
_attachedWndProc = newWndProc;
_oldWndProc = oldWndProc;
IntPtr oldWndProc2 = (IntPtr)UnsafeNativeMethods.CriticalSetWindowLong(_hwndHandleRef, NativeMethods.GWL_WNDPROC, _attachedWndProc);
// Track this window so that we can rip out the managed window proc
// when the CLR shuts down.
ManagedWndProcTracker.TrackHwndSubclass(this, _hwndAttached);
}
// This method should only be called from Dispose. Otherwise assumptions about the disposing/finalize state could be violated.
// force - when true, remove this subclass from the WndProc chain regardless of
// its current position. When false, remove this subclass only
// if it is possible to do so without damaging other WndProcs
// (i.e. only if this is at the head of the chain).
//
// Removing this subclass from the WndProc chain when it is not at the head
// also removes all other WndProcs that appear before this one on the chain,
// so is generally not appropriate. It is OK in the following situations:
// a) in response to the WM_NCDESTROY message
// b) in response to the AppDomainProcessExit event
// c) in response to the AppDomainExit event
// In cases (a) and (b) the HWND is being destroyed, so the earlier
// WndProcs are no longer useful anyway. In case (c), we have to remove
// all managed code from the chain lest it be called after it has been
// removed from memory; removing earlier WndProcs is unfortunate, but
// necessary. [Note that at AppDomainExit we remove all managed WndProcs,
// regardless of which AppDomain they came from. There is room for
// improvement here - we could remove only the ones belong to the AppDomain
// that is exiting. This situation seems too unlikely to worry about in V1.]
//
// This method returns true if the subclass is no longer in the WndProc chain.
//
///
/// Critical - Calls CriticalSetWindowLong() and GetWindowLongWndProc().
/// This touches the underlying windowing infrastructure; we may want to intercept windows-messages for security-related purposes in the future.
/// In general we restrict access to window handles.
///
[SecurityCritical]
private bool UnhookWindowProc(bool force)
{
// if we're not in the WndProc chain, there's nothing to do
if (_bond == Bond.Unattached || _bond == Bond.Detached)
{
return true;
}
// we'll remove ourselves from the chain if we're at the head, or if
// the 'force' parameter was true.
if (!force)
{
NativeMethods.WndProc currentWndProc = UnsafeNativeMethods.GetWindowLongWndProc(new HandleRef(this,_hwndAttached));
force = (currentWndProc == _attachedWndProc);
}
// if we're not unhooking, return and report
if (!force)
{
return false;
}
// unhook from the tracker
_bond = Bond.Orphaned; // ignore messages while we're unhooking
ManagedWndProcTracker.UnhookHwndSubclass(this);
// unhook, the Win32 way
try
{
UnsafeNativeMethods.CriticalSetWindowLong(_hwndHandleRef, NativeMethods.GWL_WNDPROC, _oldWndProc);
}
catch (System.ComponentModel.Win32Exception e)
{
if (e.NativeErrorCode != 1400) // ERROR_INVALID_WINDOW_HANDLE
{
throw;
}
}
// clear our state
_bond = Bond.Detached;
_oldWndProc = IntPtr.Zero;
_attachedWndProc = null;
_hwndAttached = IntPtr.Zero;
_hwndHandleRef = new HandleRef(null,IntPtr.Zero);
// un-Pin this object.
// Note: the GC is free to collect this object at anytime
// after we have freed this handle - that is, once all
// other managed references go away.
//AvDebug.Assert(_gcHandle.IsAllocated, "External GC handle has not been allocated.");
if(null != _gcHandle)
_gcHandle.Free();
return true;
}
///
/// DefWndProcWrapper is a wrapper around DefWndProc. This is a workaround
/// for WindowsSE bugs 124461 and 124455, which affect Windows XP SP2, Luna theme.
///
/// HwndSubclass.SubclassWndProc is sometimes directly set as the window proc of a
/// Window (HwndWrapper's constructor does this). When this happens it subclasses
/// itself on the first message it receives. Since the old window proc is itself,
/// it saves off DefWndProc as the old window proc instead.
///
/// As described by the bugs and and KB article 319740, if we set DefWndProc
/// as the window proc of the window, we'll leak 6 GDI region objects
/// corresponding to the Luna-themed non-client area.
///
/// The reason for this is that the kernel will flag that window as a server-side
/// window. If the WndProc replacement happens in response to a WM_NCDESTROY message
/// (as it does in the case where Avalon is creating and closing windows), the Shell
/// won't clean up the regions.
///
/// The fix is slated for XP SP3, so for now WPF is implementing a workaround:
/// if we set the window proc to be a stub that calls into DefWndProc, the kernel
/// won't set us as a server-side window.
///
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
private static IntPtr DefWndProcWrapper(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
{
return UnsafeNativeMethods.CallWindowProc(DefWndProc, hwnd, msg, wParam, lParam);
}
// Message to cause a detach.
// WPARAM=IntPtr returned from Attach(), or 0 to match all subclasses.
// LPARAM= 0 - normal (unhook subclass if it is first on the chain)
// 1 - force unhooking subclass from the chain
// 2 - force, and forward message to next WndProc
internal static readonly int DetachMessage;
private enum Bond
{
Unattached,
Attached,
Detached,
Orphaned
}
///
/// This is a delegate that points to DefWndProcWrapper. It is set into
/// a Window's WndProc instead of DefWndProc in order to work around a bug.
/// See the comment on DefWndProcWrapper.
///
/// By instantiating this delegate as a static variable we ensure that
/// it will remain alive long enough to process messages.
///
///
/// Critical: This will expose DefWndProc
///
[SecurityCritical]
private static NativeMethods.WndProc DefWndProcStub = new NativeMethods.WndProc(DefWndProcWrapper);
///
/// Critical: This will expose wndproc
///
[SecurityCritical]
private static IntPtr DefWndProc;
///
/// Critical: This will expose the intptr of the window
///
[SecurityCritical]
private IntPtr _hwndAttached;
///
/// Critical: This will expose window handle
///
[SecurityCritical]
private HandleRef _hwndHandleRef;
///
/// Critical: This will expose wndproc
///
[SecurityCritical]
private NativeMethods.WndProc _attachedWndProc;
///
/// Critical: This will expose wndproc
///
[SecurityCritical]
private IntPtr _oldWndProc;
private Bond _bond;
private GCHandle _gcHandle;
///
/// Critical: This will expose hook
///
[SecurityCritical]
private WeakReference _hook;
};
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
using System;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using MS.Internal;
using MS.Utility;
using System.Windows;
using System.Windows.Threading;
using System.Security; // CAS
using System.Threading; // Thread
// The SecurityHelper class differs between assemblies and could not actually be
// shared, so it is duplicated across namespaces to prevent name collision.
#if WINDOWS_BASE
using MS.Internal.WindowsBase;
#elif PRESENTATION_CORE
using MS.Internal.PresentationCore;
#elif PRESENTATIONFRAMEWORK
using MS.Internal.PresentationFramework;
#elif DRT
using MS.Internal.Drt;
#else
#error Attempt to use a class (duplicated across multiple namespaces) from an unknown assembly.
#endif
namespace MS.Win32
{
///
/// The HwndSubclass class provides a managed way to subclass an existing
/// HWND. This class inserts itself into the WNDPROC chain for the
/// window, and will call a specified delegate to process the window
/// messages that arrive. The delegate has a slightly different
/// signature than a WNDPROC to be more specific about whether the
/// message was handled or not. If the message was not handled by the
/// delegate, this class passes the message on down the WNDPROC chain.
///
/// To use this class properly, simply:
/// 1) Create an instance of the HwndSubclass class and pass the delegate
/// to the constructor.
/// 2) Call Attach(HWND) to subclass an existing window.
/// 3) Call Detach(false) to unsubclass the window when you are done.
///
/// You can also just call RequestDetach() to send a message to the
/// window that will cause the HwndSubclass to detach itself. This is
/// important if you are on a different thread, as the HwndSubclass class
/// is not thread safe and will be operated on by the thread that owns
/// the window.
///
/// Not available to partial trust callers
[FriendAccessAllowed] // Built into Base, also used by Framework
internal class HwndSubclass : IDisposable
{
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
static HwndSubclass()
{
DetachMessage = UnsafeNativeMethods.RegisterWindowMessage("HwndSubclass.DetachMessage");
if (DetachMessage == 0)
{
throw new System.ComponentModel.Win32Exception();
}
// Go find the address of DefWindowProc.
IntPtr hModuleUser32 = UnsafeNativeMethods.GetModuleHandle(ExternDll.User32);
IntPtr address = UnsafeNativeMethods.GetProcAddress(new HandleRef(null,hModuleUser32), "DefWindowProcW");
DefWndProc = address;
}
///
/// This HwndSubclass constructor binds the HwndSubclass object to the
/// specified delegate. This delegate will be called to process
/// the messages that are sent or posted to the window.
///
///
/// The delegate that will be called to process the messages that
/// are sent or posted to the window.
///
///
/// Nothing.
///
///
/// Critical: This code creates an object that is not allowed in partial trust
///
[SecurityCritical]
internal HwndSubclass(HwndWrapperHook hook)
{
if(hook == null)
{
throw new ArgumentNullException("hook");
}
_bond = Bond.Unattached;
_hook = new WeakReference(hook);
// Allocate a GC handle so that we won't be collected, even if all
// references to us get released. This is because a component outside
// of the managed code (ie. the window we are subclassing) still holds
// a reference to us - just not a reference that the GC recognizes.
_gcHandle = GCHandle.Alloc(this);
}
// This is LIVE OBJECT because it has a GCHandle. The only time LIVE OBJECTS
// are destroyed is during Shutdown. But Shutdown cleanup is handled through
// the ManagedWndProcTracker and hence no work needs to happen here. PLEASE
// NOTE that reintroducing any cleanup logic in here will conflict with the cleanup
// logic in ManagedWndProcTracker and hence must be avoided. If this instance
// has been disposed its GCHandle is released at the time and hence this object
// is available for GC thereafter. Even in that case since all the cleanup has been
// done during dispose there is no further cleanup required.
// ///
// /// Critical - It calls the critical DisposeImpl.
// ///
// [SecurityCritical]
// ~HwndSubclass()
// {
// // In Shutdown, the finalizer is called on LIVE OBJECTS.
// //
// // So this method can be called. (even though we are pinned)
// // If it is, we're shutting down so it's OK to force unhooking
// // the subclass.
// DisposeImpl(true);
// }
///
/// Critical - It calls the critical DisposeImpl.
/// PublicOK - Demands for AllWindows permission.
///
[SecurityCritical]
public virtual void Dispose()
{
SecurityHelper.DemandUIWindowPermission();
DisposeImpl(false);
}
///
/// Critical - Calls the critical UnhookWindowProc.
///
[SecurityCritical]
private bool DisposeImpl(bool forceUnhook)
{
_hook = null;
return UnhookWindowProc(forceUnhook);
}
///
/// This method subclasses the specified window, such that the
/// delegate specified to the constructor will be called to process
/// the messages that are sent or posted to this window.
///
///
/// The window to subclass.
///
///
/// An identifier that can be used to reference this instance of
/// the HwndSubclass class in the static RequestDetach method.
///
///
/// Critical - It calls CriticalAttach.
/// TreatAsSafe - Demands for AllWindows permission.
///
[SecurityCritical, SecurityTreatAsSafe]
internal IntPtr Attach(IntPtr hwnd)
{
SecurityHelper.DemandUIWindowPermission();
if (_bond != Bond.Unattached)
throw new InvalidOperationException(SR.Get(SRID.HwndSubclassMultipleAttach));
return CriticalAttach( hwnd ) ;
}
///
/// This method unsubclasses this HwndSubclass object from the window
/// it previously subclassed. The HwndSubclass object is not thread
/// safe, and should thus be called only by the thread that owns
/// the window being unsubclassed.
///
///
/// Whether or not the unsubclassing should be forced. Due to the
/// way that Win32 implements window subclassing, it is not always
/// possible to safely remove a window proc from the WNDPROC chain.
/// However, the delegate will not be called again after this
/// method returns.
///
///
/// Whether or not this HwndSubclass object was actually removed from
/// the WNDPROC chain.
///
///
/// TreatAsSafe: Demands for all windows
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
internal bool Detach(bool force)
{
SecurityHelper.DemandUIWindowPermission();
return CriticalDetach(force);
}
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
internal bool CriticalDetach(bool force)
{
bool detached;
// If we have already detached, return immediately.
if(_bond == Bond.Detached || _bond == Bond.Unattached)
{
detached = true;
}
else
{
// When we detach, we simply make a note of it.
_bond = Bond.Orphaned;
// try to unhook the subclass
detached = DisposeImpl(force);
}
return detached;
}
///
/// This method sends a message to the window that is currently
/// subclassed by this instance of the HwndSubclass class, in order
/// to unsubclass the window. This is important if a different
/// thread than the thread that owns the window wants to initiate
/// the unsubclassing.
///
///
/// Whether or not the unsubclassing should be forced. Due to the
/// way that Win32 implements window subclassing, it is not always
/// possible to safely remove a window proc from the WNDPROC chain.
/// However, the delegate will not be called again after this
/// method returns.
///
///
/// Nothing.
///
///
/// Critical - Probes _hwndAttached for value.
/// TreatAsSafe - The RequestDetach overload we're calling is public and safe (demands UIWindowPermission).
///
[SecurityCritical, SecurityTreatAsSafe]
internal void RequestDetach(bool force)
{
// Let the static version do the work.
if(_hwndAttached != IntPtr.Zero)
{
RequestDetach(_hwndAttached, (IntPtr) _gcHandle, force);
}
}
///
/// This method sends a message to the specified window in order to
/// cause the specified bridge to unsubclass the window. This is
/// important if a different thread than the thread that owns the
/// window wants to initiate the unsubclassing. The HwndSubclass
/// object must be identified by the value returned from Attach().
///
///
/// The window to unsubclass.
///
///
/// The identifier of the subclass to unsubclass.
///
///
/// Whether or not the unsubclassing should be forced. Due to the
/// way that Win32 implements window subclassing, it is not always
/// possible to safely remove a window proc from the WNDPROC chain.
/// However, the delegate will not be called again after this
/// method returns.
///
///
/// Nothing.
///
///
/// Critical - This touches the underlying windowing infrastructure; we may want to intercept windows-messages for security-related purposes in the future.
/// In general we restrict access to window handles.
/// TreatAsSafe - Demands UIWindowPermission.
///
[SecurityCritical, SecurityTreatAsSafe]
internal static void RequestDetach(IntPtr hwnd, IntPtr subclass, bool force)
{
SecurityHelper.DemandUIWindowPermission();
if(hwnd == IntPtr.Zero)
{
throw new ArgumentNullException("hwnd");
}
if(subclass == IntPtr.Zero)
{
throw new ArgumentNullException("subclass");
}
int iForce = force ? 1 : 0;
UnsafeNativeMethods.UnsafeSendMessage(hwnd, DetachMessage, subclass, (IntPtr) iForce);
}
///
/// This is the WNDPROC that gets inserted into the window's
/// WNDPROC chain. It responds to various conditions that
/// would cause this HwndSubclass object to unsubclass the window,
/// and then calls the delegate specified to the HwndSubclass
/// constructor to process the message. If the delegate does not
/// handle the message, the message is then passed on down the
/// WNDPROC chain for further processing.
///
///
/// The window that this message was sent or posted to.
///
///
/// The message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// The value that is the result of processing the message.
///
///
/// Critical: this function elevates via unsafe native method calls
///
[SecurityCritical]
internal IntPtr SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
{
IntPtr retval = IntPtr.Zero;
bool handled = false;
// If we are unattached and we receive a message, then we must have
// been used as the original window proc. In this case, we insert
// ourselves as if the original window proc had been DefWindowProc.
// We pass in DefWndProcStub as a workaround for a bug in UxTheme on
// Windows XP. For details see the comment on the DefWndProcWrapper method.
if(_bond == Bond.Unattached)
{
HookWindowProc(hwnd, new NativeMethods.WndProc(SubclassWndProc),
Marshal.GetFunctionPointerForDelegate(DefWndProcStub));
}
else if(_bond == Bond.Detached)
{
throw new InvalidOperationException();
}
IntPtr oldWndProc = _oldWndProc; // in case we get detached during this method
if(msg == DetachMessage)
{
// We received our special message to detach. Make sure it is intended
// for us by matching the bridge.
if(wParam == IntPtr.Zero || wParam == (IntPtr)_gcHandle)
{
int param = (int)lParam; // 0 - normal, 1 - force, 2 - force and forward
bool force = (param > 0);
retval = CriticalDetach(force) ? new IntPtr(1) : IntPtr.Zero ;
handled = (param < 2);
}
}
else
{
// Pass this message to our delegate function. Do this under
// the exception filter/handlers of the dispatcher for this thread.
Dispatcher dispatcher = Dispatcher.FromThread(Thread.CurrentThread);
if(dispatcher != null && !dispatcher.HasShutdownFinished)
{
if (_dispatcherOperationCallback == null)
_dispatcherOperationCallback = new DispatcherOperationCallback(this.DispatcherCallbackOperation);
// _paramDispatcherCallbackOperation is a thread static member which should be reused to avoid
// creating a new data structure every time we call DispatcherCallbackOperation
// Cache the param locally in case of reentrance and set _paramDispatcherCallbackOperation to null so reentrancy calls will create a new param
if (_paramDispatcherCallbackOperation == null)
_paramDispatcherCallbackOperation = new DispatcherOperationCallbackParameter();
DispatcherOperationCallbackParameter param = _paramDispatcherCallbackOperation;
_paramDispatcherCallbackOperation = null;
param.hwnd = hwnd;
param.msg = msg;
param.wParam = wParam;
param.lParam = lParam;
//synchronous call
object result = dispatcher.Invoke(
DispatcherPriority.Send,
_dispatcherOperationCallback,
param);
if (result != null)
{
handled = param.handled;
retval = param.retVal;
}
// Restore _paramDispatcherCallbackOperation to the previous value so we will reuse it on the next call
_paramDispatcherCallbackOperation = param;
}
// Handle WM_NCDESTROY explicitly to forcibly clean up.
if(msg == NativeMethods.WM_NCDESTROY)
{
// The fact that we received this message means that we are
// still in the call chain. This is our last chance to clean
// up, and no other message should be received by this window
// proc again. It is OK to force a cleanup now.
CriticalDetach(true);
// Always pass the WM_NCDESTROY message down the chain!
handled = false;
}
}
// If our window proc didn't handle this message, pass it on down the
// chain.
if(!handled)
{
retval = CallOldWindowProc(oldWndProc, hwnd, msg, wParam, lParam);
}
return retval;
}
// Perf bug: 1963989
// _paramDispatcherCallbackOperation is a thread static member which should be reused to avoid
// creating a new data structure every time we DispatcherCallbackOperation is called
// It also contains the return results (handled and retValue) from DispatcherCallbackOperation call
///
/// Critical: DispatcherOperationCallbackParameter contains hwnd, which is critical
///
[SecurityCritical]
[ThreadStatic]
private static DispatcherOperationCallbackParameter _paramDispatcherCallbackOperation;
// This class is used as a parameter and return result for DispatcherCallbackOperation call
private class DispatcherOperationCallbackParameter
{
internal IntPtr hwnd, wParam, lParam, retVal;
internal int msg;
internal bool handled;
}
private DispatcherOperationCallback _dispatcherOperationCallback = null;
///
/// Critical: it calls GetWindowLongPtr(), which is Critical
///
[ SecurityCritical ]
internal IntPtr CriticalAttach( IntPtr hwnd )
{
if(hwnd == IntPtr.Zero)
{
throw new ArgumentNullException("hwnd");
}
if(_bond != Bond.Unattached)
{
throw new InvalidOperationException();
}
NativeMethods.WndProc newWndProc = new NativeMethods.WndProc(SubclassWndProc);
IntPtr oldWndProc = UnsafeNativeMethods.GetWindowLongPtr(new HandleRef(this,hwnd), NativeMethods.GWL_WNDPROC);
HookWindowProc(hwnd, newWndProc, oldWndProc);
// Return the GC handle as a unique identifier of this
return (IntPtr) _gcHandle;
}
///
/// Critical: This code is a callback into the dispatcher. It is present
/// because under enforcements anonymous delagates throw a demand since
/// it becomes a transparent calling critical for this particular call
///
[SecurityCritical]
private object DispatcherCallbackOperation(object o)
{
DispatcherOperationCallbackParameter param = (DispatcherOperationCallbackParameter)o;
param.handled = false;
param.retVal = IntPtr.Zero;
if (_bond == Bond.Attached)
{
HwndWrapperHook hook= _hook.Target as HwndWrapperHook;
if (hook != null)
{
// make the call
param.retVal = hook(param.hwnd, param.msg, param.wParam, param.lParam, ref param.handled);
}
}
return param;
}
///
/// This method lets the user call the old WNDPROC, i.e
/// the next WNDPROC in the chain directly.
///
///
/// The WndProc to call.
///
///
/// The window that this message was sent or posted to.
///
///
/// The message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// A parameter for the message that was sent or posted.
///
///
/// The value that is the result of processing the message.
///
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
IntPtr CallOldWindowProc(IntPtr oldWndProc, IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam)
{
return UnsafeNativeMethods.CallWindowProc(oldWndProc, hwnd, msg, wParam, lParam);
}
///
/// Critical - it calls CriticalSetWindowLong()
///
[SecurityCritical]
private void HookWindowProc(IntPtr hwnd, NativeMethods.WndProc newWndProc, IntPtr oldWndProc)
{
_hwndAttached = hwnd;
_hwndHandleRef = new HandleRef(null,_hwndAttached);
_bond = Bond.Attached;
_attachedWndProc = newWndProc;
_oldWndProc = oldWndProc;
IntPtr oldWndProc2 = (IntPtr)UnsafeNativeMethods.CriticalSetWindowLong(_hwndHandleRef, NativeMethods.GWL_WNDPROC, _attachedWndProc);
// Track this window so that we can rip out the managed window proc
// when the CLR shuts down.
ManagedWndProcTracker.TrackHwndSubclass(this, _hwndAttached);
}
// This method should only be called from Dispose. Otherwise assumptions about the disposing/finalize state could be violated.
// force - when true, remove this subclass from the WndProc chain regardless of
// its current position. When false, remove this subclass only
// if it is possible to do so without damaging other WndProcs
// (i.e. only if this is at the head of the chain).
//
// Removing this subclass from the WndProc chain when it is not at the head
// also removes all other WndProcs that appear before this one on the chain,
// so is generally not appropriate. It is OK in the following situations:
// a) in response to the WM_NCDESTROY message
// b) in response to the AppDomainProcessExit event
// c) in response to the AppDomainExit event
// In cases (a) and (b) the HWND is being destroyed, so the earlier
// WndProcs are no longer useful anyway. In case (c), we have to remove
// all managed code from the chain lest it be called after it has been
// removed from memory; removing earlier WndProcs is unfortunate, but
// necessary. [Note that at AppDomainExit we remove all managed WndProcs,
// regardless of which AppDomain they came from. There is room for
// improvement here - we could remove only the ones belong to the AppDomain
// that is exiting. This situation seems too unlikely to worry about in V1.]
//
// This method returns true if the subclass is no longer in the WndProc chain.
//
///
/// Critical - Calls CriticalSetWindowLong() and GetWindowLongWndProc().
/// This touches the underlying windowing infrastructure; we may want to intercept windows-messages for security-related purposes in the future.
/// In general we restrict access to window handles.
///
[SecurityCritical]
private bool UnhookWindowProc(bool force)
{
// if we're not in the WndProc chain, there's nothing to do
if (_bond == Bond.Unattached || _bond == Bond.Detached)
{
return true;
}
// we'll remove ourselves from the chain if we're at the head, or if
// the 'force' parameter was true.
if (!force)
{
NativeMethods.WndProc currentWndProc = UnsafeNativeMethods.GetWindowLongWndProc(new HandleRef(this,_hwndAttached));
force = (currentWndProc == _attachedWndProc);
}
// if we're not unhooking, return and report
if (!force)
{
return false;
}
// unhook from the tracker
_bond = Bond.Orphaned; // ignore messages while we're unhooking
ManagedWndProcTracker.UnhookHwndSubclass(this);
// unhook, the Win32 way
try
{
UnsafeNativeMethods.CriticalSetWindowLong(_hwndHandleRef, NativeMethods.GWL_WNDPROC, _oldWndProc);
}
catch (System.ComponentModel.Win32Exception e)
{
if (e.NativeErrorCode != 1400) // ERROR_INVALID_WINDOW_HANDLE
{
throw;
}
}
// clear our state
_bond = Bond.Detached;
_oldWndProc = IntPtr.Zero;
_attachedWndProc = null;
_hwndAttached = IntPtr.Zero;
_hwndHandleRef = new HandleRef(null,IntPtr.Zero);
// un-Pin this object.
// Note: the GC is free to collect this object at anytime
// after we have freed this handle - that is, once all
// other managed references go away.
//AvDebug.Assert(_gcHandle.IsAllocated, "External GC handle has not been allocated.");
if(null != _gcHandle)
_gcHandle.Free();
return true;
}
///
/// DefWndProcWrapper is a wrapper around DefWndProc. This is a workaround
/// for WindowsSE bugs 124461 and 124455, which affect Windows XP SP2, Luna theme.
///
/// HwndSubclass.SubclassWndProc is sometimes directly set as the window proc of a
/// Window (HwndWrapper's constructor does this). When this happens it subclasses
/// itself on the first message it receives. Since the old window proc is itself,
/// it saves off DefWndProc as the old window proc instead.
///
/// As described by the bugs and and KB article 319740, if we set DefWndProc
/// as the window proc of the window, we'll leak 6 GDI region objects
/// corresponding to the Luna-themed non-client area.
///
/// The reason for this is that the kernel will flag that window as a server-side
/// window. If the WndProc replacement happens in response to a WM_NCDESTROY message
/// (as it does in the case where Avalon is creating and closing windows), the Shell
/// won't clean up the regions.
///
/// The fix is slated for XP SP3, so for now WPF is implementing a workaround:
/// if we set the window proc to be a stub that calls into DefWndProc, the kernel
/// won't set us as a server-side window.
///
///
/// Critical: Elevates by calling an UnsafeNativeMethod
///
[SecurityCritical]
private static IntPtr DefWndProcWrapper(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
{
return UnsafeNativeMethods.CallWindowProc(DefWndProc, hwnd, msg, wParam, lParam);
}
// Message to cause a detach.
// WPARAM=IntPtr returned from Attach(), or 0 to match all subclasses.
// LPARAM= 0 - normal (unhook subclass if it is first on the chain)
// 1 - force unhooking subclass from the chain
// 2 - force, and forward message to next WndProc
internal static readonly int DetachMessage;
private enum Bond
{
Unattached,
Attached,
Detached,
Orphaned
}
///
/// This is a delegate that points to DefWndProcWrapper. It is set into
/// a Window's WndProc instead of DefWndProc in order to work around a bug.
/// See the comment on DefWndProcWrapper.
///
/// By instantiating this delegate as a static variable we ensure that
/// it will remain alive long enough to process messages.
///
///
/// Critical: This will expose DefWndProc
///
[SecurityCritical]
private static NativeMethods.WndProc DefWndProcStub = new NativeMethods.WndProc(DefWndProcWrapper);
///
/// Critical: This will expose wndproc
///
[SecurityCritical]
private static IntPtr DefWndProc;
///
/// Critical: This will expose the intptr of the window
///
[SecurityCritical]
private IntPtr _hwndAttached;
///
/// Critical: This will expose window handle
///
[SecurityCritical]
private HandleRef _hwndHandleRef;
///
/// Critical: This will expose wndproc
///
[SecurityCritical]
private NativeMethods.WndProc _attachedWndProc;
///
/// Critical: This will expose wndproc
///
[SecurityCritical]
private IntPtr _oldWndProc;
private Bond _bond;
private GCHandle _gcHandle;
///
/// Critical: This will expose hook
///
[SecurityCritical]
private WeakReference _hook;
};
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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