Enable the Terminal to tell ConPTY who the owner is

.github/actions/spelling/allow/apis.txt

@@ -145,6 +145,7 @@ REGCLS
 RETURNCMD
 rfind
 roundf
+ROOTOWNER
 RSHIFT
 SACL
 schandle

src/cascadia/TerminalApp/TerminalPage.cpp

@@ -60,6 +60,12 @@ namespace winrt::TerminalApp::implementation
 
     // Method Description:
     // - implements the IInitializeWithWindow interface from shobjidl_core.
+    // - We're going to use this HWND as the owner for the ConPTY windows, via
+    //   ConptyConnection::ReparentWindow. We need this for applications that
+    //   call GetConsoleWindow, and attempt to open a MessageBox for the
+    //   console. By marking the conpty windows as owned by the Terminal HWND,
+    //   the message box will be owned by the Terminal window as well.
+    //   - see GH#2988
     HRESULT TerminalPage::Initialize(HWND hwnd)
     {
         _hostingHwnd = hwnd;
@@ -2424,6 +2430,11 @@ namespace winrt::TerminalApp::implementation
         // create here.
         // TermControl will copy the settings out of the settings passed to it.
         TermControl term{ settings.DefaultSettings(), settings.UnfocusedSettings(), connection };
+
+        if (_hostingHwnd.has_value())
+        {
+            term.OwningHwnd(reinterpret_cast<uint64_t>(*_hostingHwnd));
+        }
         return term;
     }
 

src/cascadia/TerminalConnection/ConptyConnection.cpp

@@ -310,6 +310,12 @@ namespace winrt::Microsoft::Terminal::TerminalConnection::implementation
             }
 
             THROW_IF_FAILED(_CreatePseudoConsoleAndPipes(dimensions, flags, &_inPipe, &_outPipe, &_hPC));
+
+            if (_initialParentHwnd != 0)
+            {
+                THROW_IF_FAILED(ConptyReparentPseudoConsole(_hPC.get(), reinterpret_cast<HWND>(_initialParentHwnd)));
+            }
+
             THROW_IF_FAILED(_LaunchAttachedClient());
         }
         // But if it was an inbound handoff... attempt to synchronize the size of it with what our connection
@@ -327,6 +333,7 @@ namespace winrt::Microsoft::Terminal::TerminalConnection::implementation
                 TelemetryPrivacyDataTag(PDT_ProductAndServicePerformance));
 
             THROW_IF_FAILED(ConptyResizePseudoConsole(_hPC.get(), dimensions));
+            THROW_IF_FAILED(ConptyReparentPseudoConsole(_hPC.get(), reinterpret_cast<HWND>(_initialParentHwnd)));
         }
 
         _startTime = std::chrono::high_resolution_clock::now();
@@ -482,6 +489,22 @@ namespace winrt::Microsoft::Terminal::TerminalConnection::implementation
         }
     }
 
+    void ConptyConnection::ReparentWindow(const uint64_t newParent)
+    {
+        // If we haven't started connecting at all, stash this HWND to use once we have started.
+        if (!_isStateAtOrBeyond(ConnectionState::Connecting))
+        {
+            _initialParentHwnd = newParent;
+        }
+        // Otherwise, just inform the conpty of the new owner window handle.
+        // This shouldn't be hittable until GH#5000 / GH#1256, when it's
+        // possible to reparent terminals to different windows.
+        else if (_isConnected())
+        {
+            THROW_IF_FAILED(ConptyReparentPseudoConsole(_hPC.get(), reinterpret_cast<HWND>(newParent)));
+        }
+    }
+
     void ConptyConnection::Close() noexcept
     try
     {

src/cascadia/TerminalConnection/ConptyConnection.h

@@ -35,6 +35,7 @@ namespace winrt::Microsoft::Terminal::TerminalConnection::implementation
         void Resize(uint32_t rows, uint32_t columns);
         void Close() noexcept;
         void ClearBuffer();
+        void ReparentWindow(const uint64_t newParent);
 
         winrt::guid Guid() const noexcept;
         winrt::hstring Commandline() const;
@@ -65,6 +66,7 @@ namespace winrt::Microsoft::Terminal::TerminalConnection::implementation
 
         uint32_t _initialRows{};
         uint32_t _initialCols{};
+        uint64_t _initialParentHwnd{ 0 };
         hstring _commandline{};
         hstring _startingDirectory{};
         hstring _startingTitle{};

src/cascadia/TerminalConnection/ConptyConnection.idl

@@ -13,6 +13,7 @@ namespace Microsoft.Terminal.TerminalConnection
         Guid Guid { get; };
         String Commandline { get; };
         void ClearBuffer();
+        void ReparentWindow(UInt64 newParent);
 
         static event NewConnectionHandler NewConnection;
         static void StartInboundListener();

src/cascadia/TerminalControl/ControlCore.cpp

@@ -262,6 +262,14 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             const auto height = vp.Height();
             _connection.Resize(height, width);
 
+            if (_OwningHwnd != 0)
+            {
+                if (auto conpty{ _connection.try_as<TerminalConnection::ConptyConnection>() })
+                {
+                    conpty.ReparentWindow(_OwningHwnd);
+                }
+            }
+
             // Override the default width and height to match the size of the swapChainPanel
             _settings->InitialCols(width);
             _settings->InitialRows(height);

src/cascadia/TerminalControl/ControlCore.h

@@ -168,6 +168,11 @@ namespace winrt::Microsoft::Terminal::Control::implementation
 
         void AdjustOpacity(const double opacity, const bool relative);
 
+        // TODO:GH#1256 - When a tab can be torn out or otherwise reparented to
+        // another window, this value will need a custom setter, so that we can
+        // also update the connection.
+        WINRT_PROPERTY(uint64_t, OwningHwnd, 0);
+
         RUNTIME_SETTING(double, Opacity, _settings->Opacity());
         RUNTIME_SETTING(bool, UseAcrylic, _settings->UseAcrylic());
 

src/cascadia/TerminalControl/ICoreState.idl

@@ -24,5 +24,8 @@ namespace Microsoft.Terminal.Control
         Microsoft.Terminal.TerminalConnection.ConnectionState ConnectionState { get; };
 
         Microsoft.Terminal.Core.Scheme ColorScheme { get; set; };
+
+        UInt64 OwningHwnd;
+
     };
 }

src/cascadia/TerminalControl/TermControl.cpp

@@ -2794,4 +2794,14 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         }
     }
 
+    void TermControl::OwningHwnd(uint64_t owner)
+    {
+        _core.OwningHwnd(owner);
+    }
+
+    uint64_t TermControl::OwningHwnd()
+    {
+        return _core.OwningHwnd();
+    }
+
 }

src/cascadia/TerminalControl/TermControl.h

@@ -59,6 +59,9 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         bool BracketedPasteEnabled() const noexcept;
 
         double BackgroundOpacity() const;
+
+        uint64_t OwningHwnd();
+        void OwningHwnd(uint64_t owner);
 #pragma endregion
 
         void ScrollViewport(int viewTop);

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -41,6 +41,11 @@ IslandWindow::~IslandWindow()
     _source.Close();
 }
 
+HWND IslandWindow::GetInteropHandle() const
+{
+    return _interopWindowHandle;
+}
+
 // Method Description:
 // - Create the actual window that we'll use for the application.
 // Arguments:

src/cascadia/WindowsTerminal/IslandWindow.h

@@ -23,6 +23,7 @@ class IslandWindow :
     virtual void MakeWindow() noexcept;
     void Close();
     virtual void OnSize(const UINT width, const UINT height);
+    HWND GetInteropHandle() const;
 
     [[nodiscard]] virtual LRESULT MessageHandler(UINT const message, WPARAM const wparam, LPARAM const lparam) noexcept override;
     void OnResize(const UINT width, const UINT height) override;

src/host/PtySignalInputThread.cpp

@@ -56,6 +56,10 @@ DWORD WINAPI PtySignalInputThread::StaticThreadProc(_In_ LPVOID lpParameter)
 //      (in and screen buffers) haven't yet been initialized.
 // - NOTE: Call under LockConsole() to ensure other threads have an opportunity
 //         to set early-work state.
+// - We need to do this specifically on the thread with the message pump. If the
+//   window is created on another thread, then the window won't have a message
+//   pump associated with it, and a DPI change in the connected terminal could
+//   end up HANGING THE CONPTY (for example).
 // Arguments:
 // - <none>
 // Return Value:
@@ -67,6 +71,12 @@ void PtySignalInputThread::ConnectConsole() noexcept
     {
         _DoResizeWindow(*_earlyResize);
     }
+
+    // If we were given a owner HWND, then manually start the pseudo window now.
+    if (_earlyReparent)
+    {
+        _DoSetWindowParent(*_earlyReparent);
+    }
 }
 
 // Method Description:
@@ -119,6 +129,28 @@ void PtySignalInputThread::ConnectConsole() noexcept
 
             break;
         }
+        case PtySignal::SetParent:
+        {
+            SetParentData reparentMessage = { 0 };
+            _GetData(&reparentMessage, sizeof(reparentMessage));
+
+            LockConsole();
+            auto Unlock = wil::scope_exit([&] { UnlockConsole(); });
+
+            // If the client app hasn't yet connected, stash the new owner.
+            // We'll later (PtySignalInputThread::ConnectConsole) use the value
+            // to set up the owner of the conpty window.
+            if (!_consoleConnected)
+            {
+                _earlyReparent = reparentMessage;
+            }
+            else
+            {
+                _DoSetWindowParent(reparentMessage);
+            }
+
+            break;
+        }
         default:
         {
             THROW_HR(E_UNEXPECTED);
@@ -147,6 +179,20 @@ void PtySignalInputThread::_DoClearBuffer()
     _pConApi->ClearBuffer();
 }
 
+// Method Description:
+// - Update the owner of the pseudo-window we're using for the conpty HWND. This
+//   allows to mark the pseudoconsole windows as "owner" by the terminal HWND
+//   that's actually hosting them.
+// - Refer to GH#2988
+// Arguments:
+// - data - Packet information containing owner HWND information
+// Return Value:
+// - <none>
+void PtySignalInputThread::_DoSetWindowParent(const SetParentData& data)
+{
+    _pConApi->ReparentWindow(data.handle);
+}
+
 // Method Description:
 // - Retrieves bytes from the file stream and exits or throws errors should the pipe state
 //   be compromised.

src/host/PtySignalInputThread.hpp

@@ -41,6 +41,7 @@ namespace Microsoft::Console
         enum class PtySignal : unsigned short
         {
             ClearBuffer = 2,
+            SetParent = 3,
             ResizeWindow = 8
         };
 
@@ -49,10 +50,15 @@ namespace Microsoft::Console
             unsigned short sx;
             unsigned short sy;
         };
+        struct SetParentData
+        {
+            uint64_t handle;
+        };
 
         [[nodiscard]] HRESULT _InputThread();
         bool _GetData(_Out_writes_bytes_(cbBuffer) void* const pBuffer, const DWORD cbBuffer);
         void _DoResizeWindow(const ResizeWindowData& data);
+        void _DoSetWindowParent(const SetParentData& data);
         void _DoClearBuffer();
         void _Shutdown();
 
@@ -62,5 +68,8 @@ namespace Microsoft::Console
         bool _consoleConnected;
         std::optional<ResizeWindowData> _earlyResize;
         std::unique_ptr<Microsoft::Console::VirtualTerminal::ConGetSet> _pConApi;
+
+    public:
+        std::optional<SetParentData> _earlyReparent;
     };
 }

src/host/VtIo.cpp

@@ -296,6 +296,11 @@ bool VtIo::IsUsingVt() const
 
     if (_pPtySignalInputThread)
     {
+        // IMPORTANT! Start the pseudo window on this thread. This thread has a
+        // message pump. If you DON'T, then a DPI change in the owning hwnd will
+        // cause us to get a dpi change as well, which we'll never deque and
+        // handle, effectively HANGING THE OWNER HWND.
+        //
         // Let the signal thread know that the console is connected
         _pPtySignalInputThread->ConnectConsole();
     }

src/host/outputStream.cpp

@@ -892,3 +892,17 @@ void ConhostInternalGetSet::UpdateSoftFont(const gsl::span<const uint16_t> bitPa
         pRender->UpdateSoftFont(bitPattern, cellSize, centeringHint);
     }
 }
+
+void ConhostInternalGetSet::ReparentWindow(const uint64_t handle)
+{
+    // This will initialize s_interactivityFactory for us. It will also
+    // conveniently return 0 when we're on OneCore.
+    //
+    // If the window hasn't been created yet, by some other call to
+    // LocatePseudoWindow, then this will also initialize the owner of the
+    // window.
+    if (const auto psuedoHwnd{ ServiceLocator::LocatePseudoWindow(reinterpret_cast<HWND>(handle)) })
+    {
+        LOG_LAST_ERROR_IF_NULL(::SetParent(psuedoHwnd, reinterpret_cast<HWND>(handle)));
+    }
+}

src/host/outputStream.hpp

@@ -116,6 +116,8 @@ class ConhostInternalGetSet final : public Microsoft::Console::VirtualTerminal::
                         const SIZE cellSize,
                         const size_t centeringHint) override;
 
+    void ReparentWindow(const uint64_t handle);
+
 private:
     void _modifyLines(const size_t count, const bool insert);
 

src/inc/conpty-static.h

@@ -25,6 +25,8 @@ HRESULT WINAPI ConptyResizePseudoConsole(HPCON hPC, COORD size);
 
 HRESULT WINAPI ConptyClearPseudoConsole(HPCON hPC);
 
+HRESULT WINAPI ConptyReparentPseudoConsole(HPCON hPC, HWND newParent);
+
 VOID WINAPI ConptyClosePseudoConsole(HPCON hPC);
 
 HRESULT WINAPI ConptyPackPseudoConsole(HANDLE hServerProcess, HANDLE hRef, HANDLE hSignal, HPCON* phPC);