stty: Implemented saved state parser for stty

src/uu/stty/src/stty.rs

@@ -150,6 +150,7 @@ enum ArgOptions<'a> {
     Mapping((S, u8)),
     Special(SpecialSetting),
     Print(PrintSetting),
+    SavedState(Vec<u32>),
 }
 
 impl<'a> From<AllFlags<'a>> for ArgOptions<'a> {
@@ -352,8 +353,12 @@ fn stty(opts: &Options) -> UResult<()> {
                     valid_args.push(ArgOptions::Print(PrintSetting::Size));
                 }
                 _ => {
+                    // Try to parse saved format (hex string like "6d02:5:4bf:8a3b:...")
+                    if let Some(state) = parse_saved_state(arg) {
+                        valid_args.push(ArgOptions::SavedState(state));
+                    }
                     // control char
-                    if let Some(char_index) = cc_to_index(arg) {
+                    else if let Some(char_index) = cc_to_index(arg) {
                         if let Some(mapping) = args_iter.next() {
                             let cc_mapping = string_to_control_char(mapping).map_err(|e| {
                                 let message = match e {
@@ -418,6 +423,9 @@ fn stty(opts: &Options) -> UResult<()> {
                 ArgOptions::Print(setting) => {
                     print_special_setting(setting, opts.file.as_raw_fd())?;
                 }
+                ArgOptions::SavedState(state) => {
+                    apply_saved_state(&mut termios, state)?;
+                }
             }
         }
         tcsetattr(opts.file.as_fd(), set_arg, &termios)?;
@@ -478,6 +486,29 @@ fn parse_rows_cols(arg: &str) -> Option<u16> {
     None
 }
 
+fn parse_saved_state(arg: &str) -> Option<Vec<u32>> {
+    let parts: Vec<&str> = arg.split(':').collect();
+
+    if parts.len() < 4 {
+        return None;
+    }
+
+    let is_valid_hex = |s: &&str| s.is_empty() || u32::from_str_radix(s, 16).is_ok();
+    if !parts.iter().all(is_valid_hex) {
+        return None;
+    }
+
+    let parse_hex = |part: &&str| {
+        if part.is_empty() {
+            0
+        } else {
+            u32::from_str_radix(part, 16).unwrap()
+        }
+    };
+
+    Some(parts.iter().map(parse_hex).collect())
+}
+
 fn check_flag_group<T>(flag: &Flag<T>, remove: bool) -> bool {
     remove && flag.group.is_some()
 }
@@ -857,6 +888,23 @@ fn apply_char_mapping(termios: &mut Termios, mapping: &(S, u8)) {
     termios.control_chars[mapping.0 as usize] = mapping.1;
 }
 
+fn apply_saved_state(termios: &mut Termios, state: &[u32]) -> nix::Result<()> {
+    if state.len() >= 4 {
+        termios.input_flags = InputFlags::from_bits_truncate(state[0] as _);
+        termios.output_flags = OutputFlags::from_bits_truncate(state[1] as _);
+        termios.control_flags = ControlFlags::from_bits_truncate(state[2] as _);
+        termios.local_flags = LocalFlags::from_bits_truncate(state[3] as _);
+
+        // Apply control characters (stored as u32 but used as u8)
+        for (i, &cc_val) in state.iter().skip(4).enumerate() {
+            if i < termios.control_chars.len() {
+                termios.control_chars[i] = cc_val as u8;
+            }
+        }
+    }
+    Ok(())
+}
+
 fn apply_special_setting(
     _termios: &mut Termios,
     setting: &SpecialSetting,

tests/by-util/test_stty.rs

@@ -349,3 +349,56 @@ fn non_negatable_combo() {
         .fails()
         .stderr_contains("invalid argument '-ek'");
 }
+
+#[test]
+#[cfg(unix)]
+fn test_save_and_restore() {
+    let (path, _controller, _replica) = pty_path();
+    let saved = new_ucmd!()
+        .args(&["--save", "--file", &path])
+        .succeeds()
+        .stdout_move_str();
+
+    let saved = saved.trim();
+    assert!(saved.contains(':'));
+
+    new_ucmd!().args(&["--file", &path, saved]).succeeds();
+}
+
+#[test]
+#[cfg(unix)]
+fn test_save_with_g_flag() {
+    let (path, _controller, _replica) = pty_path();
+    let saved = new_ucmd!()
+        .args(&["-g", "--file", &path])
+        .succeeds()
+        .stdout_move_str();
+
+    let saved = saved.trim();
+    assert!(saved.contains(':'));
+
+    new_ucmd!().args(&["--file", &path, saved]).succeeds();
+}
+
+#[test]
+#[cfg(unix)]
+fn test_save_restore_after_change() {
+    let (path, _controller, _replica) = pty_path();
+    let saved = new_ucmd!()
+        .args(&["--save", "--file", &path])
+        .succeeds()
+        .stdout_move_str();
+
+    let saved = saved.trim();
+
+    new_ucmd!()
+        .args(&["--file", &path, "intr", "^A"])
+        .succeeds();
+
+    new_ucmd!().args(&["--file", &path, saved]).succeeds();
+
+    new_ucmd!()
+        .args(&["--file", &path])
+        .succeeds()
+        .stdout_str_check(|s| !s.contains("intr = ^A"));
+}