LibVT: Support the DA (Device Attributes) request (final 'c')

This is used by vttest on startup to query the device for identity.

Libraries/LibVT/Terminal.cpp

@@ -491,6 +491,12 @@ void Terminal::escape$L(const ParamVector& params)
     m_need_full_flush = true;
 }
 
+void Terminal::escape$c(const ParamVector&)
+{
+    // DA - Device Attributes
+    emit_string("\033[?1;0c");
+}
+
 void Terminal::escape$M(const ParamVector& params)
 {
     int count = 1;
@@ -659,6 +665,9 @@ void Terminal::execute_escape_sequence(u8 final)
     case 'h':
         escape$h_l(false, question_param, params);
         break;
+    case 'c':
+        escape$c(params);
+        break;
     default:
         dbgprintf("Terminal::execute_escape_sequence: Unhandled final '%c'\n", final);
         break;
@@ -867,6 +876,12 @@ void Terminal::inject_string(const StringView& str)
         on_char(str[i]);
 }
 
+void Terminal::emit_string(const StringView& str)
+{
+    for (size_t i = 0; i < str.length(); ++i)
+        m_client.emit_char(str[i]);
+}
+
 void Terminal::unimplemented_escape()
 {
     StringBuilder builder;

Libraries/LibVT/Terminal.h

@@ -41,6 +41,7 @@ public:
     virtual void set_window_title(const StringView&) = 0;
     virtual void terminal_did_resize(u16 columns, u16 rows) = 0;
     virtual void terminal_history_changed() = 0;
+    virtual void emit_char(u8) = 0;
 };
 
 struct Attribute {
@@ -145,6 +146,8 @@ private:
     void unimplemented_escape();
     void unimplemented_xterm_escape();
 
+    void emit_string(const StringView&);
+
     void escape$A(const ParamVector&);
     void escape$B(const ParamVector&);
     void escape$C(const ParamVector&);
@@ -167,6 +170,7 @@ private:
     void escape$T(const ParamVector&);
     void escape$L(const ParamVector&);
     void escape$h_l(bool, bool, const ParamVector&);
+    void escape$c(const ParamVector&);
 
     TerminalClient& m_client;
 

Libraries/LibVT/TerminalWidget.cpp

@@ -679,6 +679,13 @@ void TerminalWidget::beep()
     force_repaint();
 }
 
+void TerminalWidget::emit_char(u8 ch)
+{
+    if (write(m_ptm_fd, &ch, 1) < 0) {
+        perror("emit_char: write");
+    }
+}
+
 void TerminalWidget::context_menu_event(GContextMenuEvent& event)
 {
     if (!m_context_menu) {

Libraries/LibVT/TerminalWidget.h

@@ -108,6 +108,7 @@ private:
     virtual void set_window_title(const StringView&) override;
     virtual void terminal_did_resize(u16 columns, u16 rows) override;
     virtual void terminal_history_changed() override;
+    virtual void emit_char(u8) override;
 
     void set_logical_focus(bool);