Indicate support for OSC 52 in the DA1 report (#19034)

Some applications that make use of the `OSC 52` clipboard sequence will
only do so if they can be certain that the terminal actually has that
functionality. Indicating our support for `OSC 52` in the `DA1` report
will give them an easy way to detect that.

`OSC 52` support was added to Windows Terminal in issue #5823, and to
ConHost in issue #18949.

Support for writing to the clipboard is indicated in the primary device
attributes report by the extension parameter `52`. This is obviously not
a standard DEC extension, but it's one that's been agreed upon by a
number of modern terminals. The extension is only reported when writing
to the clipboard is actually permitted (Windows Terminal has an option
to disable that).

I've updated the Device Attributes unit test to check that we're
reporting extension `52` when clipboard access is enabled, and not
reporting it when disabled.

- [x] Closes #19017
- [x] Tests added/passed

(cherry picked from commit 00ee88400aab0cd94409204ce0c6d20854ba7eff)
Service-Card-Id: PVTI_lADOAF3p4s4AmhmQzgbpe4k
Service-Version: 1.22

src/cascadia/TerminalCore/Terminal.cpp

@@ -93,7 +93,7 @@ void Terminal::UpdateSettings(ICoreSettings settings)
 
     if (_stateMachine)
     {
-        SetVtChecksumReportSupport(settings.AllowVtChecksumReport());
+        SetOptionalFeatures(settings);
     }
 
     _getTerminalInput().ForceDisableWin32InputMode(settings.ForceVTInput());
@@ -218,10 +218,13 @@ void Terminal::SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle)
     engine.Dispatch().SetCursorStyle(cursorStyle);
 }
 
-void Terminal::SetVtChecksumReportSupport(const bool enabled)
+void Terminal::SetOptionalFeatures(winrt::Microsoft::Terminal::Core::ICoreSettings settings)
 {
     auto& engine = reinterpret_cast<OutputStateMachineEngine&>(_stateMachine->Engine());
-    engine.Dispatch().SetVtChecksumReportSupport(enabled);
+    auto features = til::enumset<ITermDispatch::OptionalFeature>{};
+    features.set(ITermDispatch::OptionalFeature::ChecksumReport, settings.AllowVtChecksumReport());
+    features.set(ITermDispatch::OptionalFeature::ClipboardWrite, settings.AllowVtClipboardWrite());
+    engine.Dispatch().SetOptionalFeatures(features);
 }
 
 bool Terminal::IsXtermBracketedPasteModeEnabled() const noexcept

src/cascadia/TerminalCore/Terminal.hpp

@@ -94,7 +94,7 @@ public:
     void UpdateAppearance(const winrt::Microsoft::Terminal::Core::ICoreAppearance& appearance);
     void SetFontInfo(const FontInfo& fontInfo);
     void SetCursorStyle(const ::Microsoft::Console::VirtualTerminal::DispatchTypes::CursorStyle cursorStyle);
-    void SetVtChecksumReportSupport(const bool enabled);
+    void SetOptionalFeatures(winrt::Microsoft::Terminal::Core::ICoreSettings settings);
     bool IsXtermBracketedPasteModeEnabled() const noexcept;
     std::wstring_view GetWorkingDirectory() noexcept;
 

src/terminal/adapter/ITermDispatch.hpp

@@ -25,6 +25,12 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
 public:
     using StringHandler = std::function<bool(const wchar_t)>;
 
+    enum class OptionalFeature
+    {
+        ChecksumReport,
+        ClipboardWrite,
+    };
+
 #pragma warning(push)
 #pragma warning(disable : 26432) // suppress rule of 5 violation on interface because tampering with this is fraught with peril
     virtual ~ITermDispatch() = 0;
@@ -132,7 +138,6 @@ public:
     virtual void ScreenAlignmentPattern() = 0; // DECALN
 
     virtual void SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) = 0; // DECSCUSR
-    virtual void SetVtChecksumReportSupport(const bool enabled) = 0;
 
     virtual void SetClipboard(wil::zwstring_view content) = 0; // OSCSetClipboard
 
@@ -184,6 +189,8 @@ public:
     virtual StringHandler RestorePresentationState(const DispatchTypes::PresentationReportFormat format) = 0; // DECRSPS
 
     virtual void PlaySounds(const VTParameters parameters) = 0; // DECPS
+
+    virtual void SetOptionalFeatures(const til::enumset<OptionalFeature> features) = 0;
 };
 inline Microsoft::Console::VirtualTerminal::ITermDispatch::~ITermDispatch() = default;
 #pragma warning(pop)

src/terminal/adapter/adaptDispatch.cpp

@@ -1304,11 +1304,6 @@ void AdaptDispatch::SelectAttributeChangeExtent(const DispatchTypes::ChangeExten
     }
 }
 
-void AdaptDispatch::SetVtChecksumReportSupport(const bool enabled) noexcept
-{
-    _vtChecksumReportEnabled = enabled;
-}
-
 // Routine Description:
 // - DECRQCRA - Computes and reports a checksum of the specified area of
 //   the buffer memory.
@@ -1325,7 +1320,7 @@ void AdaptDispatch::RequestChecksumRectangularArea(const VTInt id, const VTInt p
     // If this feature is not enabled, we'll just report a zero checksum.
     if constexpr (Feature_VtChecksumReport::IsEnabled())
     {
-        if (_vtChecksumReportEnabled)
+        if (_optionalFeatures.test(OptionalFeature::ChecksumReport))
         {
             // If the page number is 0, then we're meant to return a checksum of all
             // of the pages, but we have no need for that, so we'll just return 0.
@@ -1491,8 +1486,16 @@ void AdaptDispatch::DeviceAttributes()
     // 28 = Rectangular area operations
     // 32 = Text macros
     // 42 = ISO Latin-2 character set
+    // 52 = Clipboard access
 
-    _api.ReturnResponse(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42c");
+    if (_optionalFeatures.test(OptionalFeature::ClipboardWrite))
+    {
+        _api.ReturnResponse(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42;52c");
+    }
+    else
+    {
+        _api.ReturnResponse(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42c");
+    }
 }
 
 // Routine Description:
@@ -4769,3 +4772,8 @@ void AdaptDispatch::PlaySounds(const VTParameters parameters)
         _api.PlayMidiNote(noteNumber, noteNumber == 71 ? 0 : velocity, duration);
     });
 }
+
+void AdaptDispatch::SetOptionalFeatures(const til::enumset<OptionalFeature> features) noexcept
+{
+    _optionalFeatures = features;
+}

src/terminal/adapter/adaptDispatch.hpp

@@ -187,7 +187,7 @@ namespace Microsoft::Console::VirtualTerminal
 
         void PlaySounds(const VTParameters parameters) override; // DECPS
 
-        void SetVtChecksumReportSupport(const bool enabled) noexcept override;
+        void SetOptionalFeatures(const til::enumset<OptionalFeature> features) noexcept override;
 
     private:
         enum class Mode
@@ -308,7 +308,7 @@ namespace Microsoft::Console::VirtualTerminal
         std::unique_ptr<FontBuffer> _fontBuffer;
         std::shared_ptr<MacroBuffer> _macroBuffer;
         std::optional<unsigned int> _initialCodePage;
-        bool _vtChecksumReportEnabled = false;
+        til::enumset<OptionalFeature> _optionalFeatures = { OptionalFeature::ClipboardWrite };
 
         // We have two instances of the saved cursor state, because we need
         // one for the main buffer (at index 0), and another for the alt buffer

src/terminal/adapter/termDispatch.hpp

@@ -177,7 +177,7 @@ public:
 
     void PlaySounds(const VTParameters /*parameters*/) override{}; // DECPS
 
-    void SetVtChecksumReportSupport(const bool /*enabled*/) override{};
+    void SetOptionalFeatures(const til::enumset<OptionalFeature> /*features*/) override{};
 };
 
 #pragma warning(default : 26440) // Restore "can be declared noexcept" warning

src/terminal/adapter/ut_adapter/adapterTest.cpp

@@ -405,7 +405,6 @@ public:
             auto& renderer = _testGetSet->_renderer;
             auto& renderSettings = renderer._renderSettings;
             auto adapter = std::make_unique<AdaptDispatch>(*_testGetSet, &renderer, renderSettings, _terminalInput);
-            adapter->SetVtChecksumReportSupport(true);
 
             fSuccess = adapter.get() != nullptr;
             if (fSuccess)
@@ -1727,11 +1726,15 @@ public:
         Log::Comment(L"Test 1: Verify normal response.");
         _testGetSet->PrepData();
         _pDispatch->DeviceAttributes();
+        _testGetSet->ValidateInputEvent(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42;52c");
 
-        auto pwszExpectedResponse = L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42c";
-        _testGetSet->ValidateInputEvent(pwszExpectedResponse);
+        Log::Comment(L"Test 2: Verify response with clipboard disabled.");
+        _testGetSet->PrepData();
+        _pDispatch->SetOptionalFeatures({});
+        _pDispatch->DeviceAttributes();
+        _testGetSet->ValidateInputEvent(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42c");
 
-        Log::Comment(L"Test 2: Verify failure when ReturnResponse doesn't work.");
+        Log::Comment(L"Test 3: Verify failure when ReturnResponse doesn't work.");
         _testGetSet->PrepData();
         _testGetSet->_returnResponseResult = FALSE;
 
@@ -2177,6 +2180,8 @@ public:
 
         using namespace std::string_view_literals;
 
+        _pDispatch->SetOptionalFeatures(ITermDispatch::OptionalFeature::ChecksumReport);
+
         Log::Comment(L"Test 1: ASCII characters");
         outputText(L"A"sv);
         verifyChecksumReport(L"FF4F");