[terminal] Screen: Fixes XTGETTCAP response to string requests and in…

…valid numeric requests. Closes #582

Changelog.md

@@ -6,6 +6,7 @@
 - Fixes PTY write race condition.
 - Fixes installation from `.deb` (missing terminfo dependency)
 - Fixes `DECRC` with respect to `DECSTBM` enabled and `DECOM` being inverted interpreted.
+- Fixes `XTGETTCAP` (#582).
 - Improved VT backend performance (#342).
 - Improved text selection behaviour.
 - Adds preliminary implementation of `DA3` VT sequence.

src/terminal/Capabilities.cpp

@@ -464,7 +464,7 @@ unsigned StaticDatabase::numericCapability(Code _cap) const
         if (cap.code.code == _cap.code)
             return cap.value;
 
-    return -1;
+    return npos;
 }
 
 string_view StaticDatabase::stringCapability(Code _cap) const
@@ -491,7 +491,7 @@ unsigned StaticDatabase::numericCapability(string_view _cap) const
         if (tcap.name == _cap || tcap.code == _cap)
             return tcap.value;
 
-    return -1;
+    return npos;
 }
 
 string_view StaticDatabase::stringCapability(string_view _cap) const

src/terminal/Capabilities.h

@@ -85,6 +85,8 @@ namespace literals
 class Database
 {
   public:
+    constexpr static inline unsigned npos = unsigned(-1);
+
     virtual ~Database() = default;
 
     virtual bool booleanCapability(Code _cap) const = 0;

src/terminal/Screen.cpp

@@ -2493,7 +2493,7 @@ void Screen<T>::requestCapability(std::string_view _name)
 
     if (booleanCapability(_name))
         reply("\033P1+r{}\033\\", toHexString(_name));
-    else if (auto const value = numericCapability(_name); value >= 0)
+    else if (auto const value = numericCapability(_name); value != Database::npos)
     {
         auto hexValue = fmt::format("{:X}", value);
         if (hexValue.size() % 2)

src/terminal/Screen_test.cpp

@@ -3203,6 +3203,15 @@ TEST_CASE("DECCRA.Left.intersecting", "[screen]")
 }
 // }}}
 
+TEST_CASE("Screen.tcap.string", "[screen, tcap]")
+{
+    using namespace terminal;
+    auto term = MockTerm(PageSize { LineCount(3), ColumnCount(5) }, LineCount(2));
+    auto& screen = term.screen;
+    screen.write("\033P+q687061\033\\"); // HPA
+    REQUIRE(e(term.replyData) == e("\033P1+r687061=1B5B2569257031256447\033\\"));
+}
+
 TEST_CASE("Sixel.simple", "[screen]")
 {
     auto const pageSize = PageSize { LineCount(10), ColumnCount(10) };