Fix a crash on restore down

src/host/VtIo.cpp

@@ -397,3 +397,37 @@ void VtIo::_ShutdownIfNeeded()
         ServiceLocator::RundownAndExit(ERROR_BROKEN_PIPE);
     }
 }
+
+// Method Description:
+// - Tell the vt renderer to begin a resize operation. During a resize
+//   operation, the vt renderer should _not_ request to be repainted during a
+//   text buffer circling event. Any callers of this method should make sure to
+//   call EndResize to make sure the renderer returns to normal behavior.
+//   See GH#1795 for context on this method.
+// Arguments:
+// - <none>
+// Return Value:
+// - <none>
+void VtIo::BeginResize()
+{
+    if (_pVtRenderEngine)
+    {
+        _pVtRenderEngine->BeginResizeRequest();
+    }
+}
+
+// Method Description:
+// - Tell the vt renderer to end a resize operation.
+//   See BeginResize for more details.
+//   See GH#1795 for context on this method.
+// Arguments:
+// - <none>
+// Return Value:
+// - <none>
+void VtIo::EndResize()
+{
+    if (_pVtRenderEngine)
+    {
+        _pVtRenderEngine->EndResizeRequest();
+    }
+}

src/host/VtIo.hpp

@@ -36,6 +36,9 @@ namespace Microsoft::Console::VirtualTerminal
         void CloseInput() override;
         void CloseOutput() override;
 
+        void BeginResize();
+        void EndResize();
+
     private:
         // After CreateIoHandlers is called, these will be invalid.
         wil::unique_hfile _hInput;

src/host/screenInfo.cpp

@@ -1670,6 +1670,19 @@ bool SCREEN_INFORMATION::IsMaximizedY() const
     CONSOLE_INFORMATION& gci = ServiceLocator::LocateGlobals().getConsoleInformation();
     NTSTATUS status = STATUS_SUCCESS;
 
+    // If we're in conpty mode, suppress any immediate painting we might do
+    // during the resize.
+    if (gci.IsInVtIoMode())
+    {
+        gci.GetVtIo()->BeginResize();
+    }
+    auto endResize = wil::scope_exit([&] {
+        if (gci.IsInVtIoMode())
+        {
+            gci.GetVtIo()->EndResize();
+        }
+    });
+
     // cancel any active selection before resizing or it will not necessarily line up with the new buffer positions
     Selection::Instance().ClearSelection();
 

src/renderer/vt/invalidate.cpp

@@ -102,11 +102,19 @@ using namespace Microsoft::Console::Render;
 // - S_OK
 [[nodiscard]] HRESULT VtEngine::InvalidateCircling(_Out_ bool* const pForcePaint) noexcept
 {
-    *pForcePaint = true;
+    // If we're in the middle of a resize request, don't try to immediately start a frame.
+    if (_inResizeRequest)
+    {
+        *pForcePaint = false;
+    }
+    else
+    {
+        *pForcePaint = true;
 
-    // Keep track of the fact that we circled, we'll need to do some work on
-    //      end paint to specifically handle this.
-    _circled = true;
+        // Keep track of the fact that we circled, we'll need to do some work on
+        //      end paint to specifically handle this.
+        _circled = true;
+    }
 
     return S_OK;
 }

src/renderer/vt/state.cpp

@@ -54,6 +54,7 @@ VtEngine::VtEngine(_In_ wil::unique_hfile pipe,
     _terminalOwner{ nullptr },
     _newBottomLine{ false },
     _deferredCursorPos{ INVALID_COORDS },
+    _inResizeRequest{ false },
     _trace{}
 {
 #ifndef UNIT_TESTING
@@ -417,3 +418,31 @@ HRESULT VtEngine::RequestCursor() noexcept
     RETURN_IF_FAILED(_Flush());
     return S_OK;
 }
+
+// Method Description:
+// - Tell the vt renderer to begin a resize operation. During a resize
+//   operation, the vt renderer should _not_ request to be repainted during a
+//   text buffer circling event. Any callers of this method should make sure to
+//   call EndResize to make sure the renderer returns to normal behavior.
+//   See GH#1795 for context on this method.
+// Arguments:
+// - <none>
+// Return Value:
+// - <none>
+void VtEngine::BeginResizeRequest()
+{
+    _inResizeRequest = true;
+}
+
+// Method Description:
+// - Tell the vt renderer to end a resize operation.
+//   See BeginResize for more details.
+//   See GH#1795 for context on this method.
+// Arguments:
+// - <none>
+// Return Value:
+// - <none>
+void VtEngine::EndResizeRequest()
+{
+    _inResizeRequest = false;
+}

src/renderer/vt/vtrenderer.hpp

@@ -94,6 +94,8 @@ namespace Microsoft::Console::Render
         [[nodiscard]] virtual HRESULT WriteTerminalW(const std::wstring& str) noexcept = 0;
 
         void SetTerminalOwner(Microsoft::Console::ITerminalOwner* const terminalOwner);
+        void BeginResizeRequest();
+        void EndResizeRequest();
 
     protected:
         wil::unique_hfile _hFile;
@@ -132,6 +134,7 @@ namespace Microsoft::Console::Render
         Microsoft::Console::ITerminalOwner* _terminalOwner;
 
         Microsoft::Console::VirtualTerminal::RenderTracing _trace;
+        bool _inResizeRequest{ false };
 
         [[nodiscard]] HRESULT _Write(std::string_view const str) noexcept;
         [[nodiscard]] HRESULT _WriteFormattedString(const std::string* const pFormat, ...) noexcept;

src/terminal/adapter/InteractDispatch.cpp

@@ -114,6 +114,8 @@ bool InteractDispatch::WindowManipulation(const DispatchTypes::WindowManipulatio
         }
         break;
     case DispatchTypes::WindowManipulationType::ResizeWindowInCharacters:
+        // TODO:GH#1765 We should introduce a better `ResizeConpty` function to
+        // the ConGetSet interface, that specifically handles a conpty resize.
         if (cParams == 2)
         {
             fSuccess = DispatchCommon::s_ResizeWindow(*_pConApi, rgusParams[1], rgusParams[0]);