LibVT: Implement Bracketed Paste Mode

This mode allow us to escape any data that was not directly typed by the
user. `vim` currently uses this. If we implement it in the shell, we
could prevent newlines from being injected into the shell by pasting
text or dragging files into it (see #7276).

Userland/Libraries/LibVT/Terminal.cpp

@@ -105,6 +105,10 @@ void Terminal::alter_mode(bool should_set, Parameters params, Intermediates inte
                     m_client.set_cursor_style(None);
                 }
                 break;
+            case 2004:
+                dbgln_if(TERMINAL_DEBUG, "Setting bracketed mode enabled={}", should_set);
+                m_needs_bracketed_paste = should_set;
+                break;
             default:
                 dbgln("Terminal::alter_mode: Unimplemented private mode {} (should_set={})", mode, should_set);
                 break;

Userland/Libraries/LibVT/Terminal.h

@@ -157,6 +157,11 @@ public:
     Attribute attribute_at(const Position&) const;
 #endif
 
+    bool needs_bracketed_paste() const
+    {
+        return m_needs_bracketed_paste;
+    };
+
 protected:
     // ^EscapeSequenceExecutor
     virtual void emit_code_point(u32) override;
@@ -336,6 +341,8 @@ protected:
     CursorStyle m_cursor_style { BlinkingBlock };
     CursorStyle m_saved_cursor_style { BlinkingBlock };
 
+    bool m_needs_bracketed_paste { false };
+
     Attribute m_current_attribute;
     Attribute m_saved_attribute;
 

Userland/Libraries/LibVT/TerminalWidget.cpp

@@ -748,17 +748,14 @@ void TerminalWidget::paste()
 {
     if (m_ptm_fd == -1)
         return;
+
     auto mime_type = GUI::Clipboard::the().mime_type();
     if (!mime_type.starts_with("text/"))
         return;
     auto text = GUI::Clipboard::the().data();
     if (text.is_empty())
         return;
-    int nwritten = write(m_ptm_fd, text.data(), text.size());
+    send_non_user_input(text);
-    if (nwritten < 0) {
-        perror("write");
-        VERIFY_NOT_REACHED();
-    }
 }
 
 void TerminalWidget::copy()
@@ -1091,20 +1088,21 @@ void TerminalWidget::drop_event(GUI::DropEvent& event)
     if (event.mime_data().has_text()) {
         event.accept();
         auto text = event.mime_data().text();
-        write(m_ptm_fd, text.characters(), text.length());
+        send_non_user_input(text.bytes());
     } else if (event.mime_data().has_urls()) {
         event.accept();
         auto urls = event.mime_data().urls();
         bool first = true;
         for (auto& url : event.mime_data().urls()) {
-            if (!first) {
+            if (!first)
-                write(m_ptm_fd, " ", 1);
+                send_non_user_input(" "sv.bytes());
-                first = false;
+
-            }
             if (url.protocol() == "file")
-                write(m_ptm_fd, url.path().characters(), url.path().length());
+                send_non_user_input(url.path().bytes());
             else
-                write(m_ptm_fd, url.to_string().characters(), url.to_string().length());
+                send_non_user_input(url.to_string().bytes());
+
+            first = false;
         }
     }
 }
@@ -1155,4 +1153,34 @@ void TerminalWidget::set_font_and_resize_to_fit(const Gfx::Font& font)
     set_font(font);
     resize(widget_size_for_font(font));
 }
+
+// Used for sending data that was not directly typed by the user.
+// This basically wraps the code that handles sending the escape sequence in bracketed paste mode.
+void TerminalWidget::send_non_user_input(const ReadonlyBytes& bytes)
+{
+    constexpr StringView leading_control_sequence = "\e[200~";
+    constexpr StringView trailing_control_sequence = "\e[201~";
+
+    int nwritten;
+    if (m_terminal.needs_bracketed_paste()) {
+        // We do not call write() separately for the control sequences and the data,
+        // because that would present a race condition where another process could inject data
+        // to prematurely terminate the escape. Could probably be solved by file locking.
+        Vector<u8> output;
+        output.ensure_capacity(leading_control_sequence.bytes().size() + bytes.size() + trailing_control_sequence.bytes().size());
+
+        // HACK: We don't have a `Vector<T>::unchecked_append(Span<T> const&)` yet :^(
+        output.append(leading_control_sequence.bytes().data(), leading_control_sequence.bytes().size());
+        output.append(bytes.data(), bytes.size());
+        output.append(trailing_control_sequence.bytes().data(), trailing_control_sequence.bytes().size());
+        nwritten = write(m_ptm_fd, output.data(), output.size());
+    } else {
+        nwritten = write(m_ptm_fd, bytes.data(), bytes.size());
+    }
+    if (nwritten < 0) {
+        perror("write");
+        VERIFY_NOT_REACHED();
+    }
+}
+
 }

Userland/Libraries/LibVT/TerminalWidget.h

@@ -118,6 +118,8 @@ private:
 
     void set_logical_focus(bool);
 
+    void send_non_user_input(const ReadonlyBytes&);
+
     Gfx::IntRect glyph_rect(u16 row, u16 column);
     Gfx::IntRect row_rect(u16 row);