fix: wide-char drop on resize to 1 and invalid session names (#2082)

* fix: deny invalid session name

* fix: `zellij attach --create SESSION_NAME` check session name

* fix: drain_until(1) discard widechar

* style(grid): add comment explaining the change

Co-authored-by: Aram Drevekenin <aram@poor.dev>

src/commands.rs

@@ -324,6 +324,10 @@ pub(crate) fn start_client(opts: CliArgs) {
     };
     let os_input = get_os_input(get_client_os_input);
 
+    let start_client_plan = |session_name: std::string::String| {
+        assert_session_ne(&session_name);
+    };
+
     if let Some(Command::Sessions(Sessions::Attach {
         session_name,
         create,
@@ -339,6 +343,9 @@ pub(crate) fn start_client(opts: CliArgs) {
         let client = if let Some(idx) = index {
             attach_with_session_index(config_options.clone(), idx, create)
         } else {
+            if create {
+                session_name.clone().map(start_client_plan);
+            }
             attach_with_session_name(session_name, config_options.clone(), create)
         };
 
@@ -363,10 +370,6 @@ pub(crate) fn start_client(opts: CliArgs) {
             attach_layout,
         );
     } else {
-        let start_client_plan = |session_name: std::string::String| {
-            assert_session_ne(&session_name);
-        };
-
         if let Some(session_name) = opts.session.clone() {
             start_client_plan(session_name.clone());
             start_client_impl(

src/sessions.rs

@@ -202,6 +202,14 @@ pub(crate) fn assert_session_ne(name: &str) {
         eprintln!("Session name cannot be empty. Please provide a specific session name.");
         process::exit(1);
     }
+    if name == "." || name == ".." {
+        eprintln!("Invalid session name: \"{}\".", name);
+        process::exit(1);
+    }
+    if name.contains('/') {
+        eprintln!("Session name cannot contains '/'.");
+        process::exit(1);
+    }
 
     match session_exists(name) {
         Ok(result) if !result => return,

zellij-server/src/panes/grid.rs

@@ -3218,7 +3218,9 @@ impl Row {
         let mut drained_part: VecDeque<TerminalCharacter> = VecDeque::new();
         let mut drained_part_len = 0;
         while let Some(next_character) = self.columns.remove(0) {
-            if drained_part_len + next_character.width <= x {
+            // drained_part_len == 0 here is so that if the grid is resized
+            // to a size of 1, we won't drop wide characters
+            if drained_part_len + next_character.width <= x || drained_part_len == 0 {
                 drained_part.push_back(next_character);
                 drained_part_len += next_character.width;
             } else {