LibLineEdit + Shell: Handle Termios internally and give a copy if asked

This moves the Termios logic inside LibLineEdit and allows users to
simply forget about the existence of termios if they so choose to :^)

Libraries/LibLineEdit/LineEditor.cpp

@@ -30,9 +30,7 @@
 #include <sys/ioctl.h>
 #include <unistd.h>
 
-LineEditor::LineEditor(struct termios termios)
-    : m_termios(termios)
-    , m_initialized(true)
+LineEditor::LineEditor()
 {
     struct winsize ws;
     if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0)
@@ -41,13 +39,9 @@ LineEditor::LineEditor(struct termios termios)
         m_num_columns = ws.ws_col;
 }
 
-LineEditor::LineEditor()
-    : LineEditor(termios {})
-{
-}
-
 LineEditor::~LineEditor()
 {
+    tcsetattr(0, TCSANOW, &m_default_termios);
 }
 
 void LineEditor::add_to_history(const String& line)
@@ -378,7 +372,7 @@ String LineEditor::get_line(const String& prompt)
                     do_backspace();
                 continue;
             }
-            if (ch == 0xc) {                    // ^L
+            if (ch == 0xc) { // ^L
                 printf("\033[3J\033[H\033[2J"); // Clear screen.
                 fputs(prompt.characters(), stdout);
                 for (size_t i = 0; i < m_buffer.size(); ++i)

Libraries/LibLineEdit/LineEditor.h

@@ -50,13 +50,19 @@ struct KeyCallback {
 
 class LineEditor {
 public:
-    LineEditor(struct termios);
     LineEditor();
     ~LineEditor();
 
-    void initialize(struct termios termios)
+    void initialize()
     {
         ASSERT(!m_initialized);
+        struct termios termios;
+        tcgetattr(0, &termios);
+        m_default_termios = termios; // grab a copy to restore
+        // Because we use our own line discipline which includes echoing,
+        // we disable ICANON and ECHO.
+        termios.c_lflag &= ~(ECHO | ICANON);
+        tcsetattr(0, TCSANOW, &termios);
         m_termios = termios;
         m_initialized = true;
     }
@@ -85,6 +91,9 @@ public:
     void insert(const char);
     void cut_mismatching_chars(String& completion, const String& other, size_t start_compare);
 
+    const struct termios& termios() const { return m_termios; }
+    const struct termios& default_termios() const { return m_default_termios; }
+
 private:
     void vt_save_cursor();
     void vt_restore_cursor();
@@ -98,7 +107,7 @@ private:
     HashMap<char, NonnullOwnPtr<KeyCallback>> m_key_callbacks;
 
     // TODO: handle signals internally
-    struct termios m_termios;
+    struct termios m_termios, m_default_termios;
     bool m_was_interrupted = false;
     bool m_was_resized = false;
 

Shell/main.cpp

@@ -1031,14 +1031,11 @@ int main(int argc, char** argv)
 
     g.uid = getuid();
     tcsetpgrp(0, getpgrp());
-    tcgetattr(0, &g.default_termios);
-    g.termios = g.default_termios;
-    // Because we use our own line discipline which includes echoing,
-    // we disable ICANON and ECHO.
-    g.termios.c_lflag &= ~(ECHO | ICANON);
-    tcsetattr(0, TCSANOW, &g.termios);
-
-    editor.initialize(g.termios);
+
+    editor.initialize();
+    g.termios = editor.termios();
+    g.default_termios = editor.default_termios();
+
     editor.on_tab_complete_first_token = [&](const String& token) -> Vector<String> {
         auto match = binary_search(cached_path.data(), cached_path.size(), token, [](const String& token, const String& program) -> int {
             return strncmp(token.characters(), program.characters(), token.length());