fix(compatibility): fix crash and don't allow cursor beyond row width (#1349)

* fix(compatibility): fix crash and don't allow cursor beyond row width

* style(fmt): rustfmt

5 files changed, 72 insertions, 70 deletions

diff --git a/zellij-server/src/panes/grid.rs b/zellij-server/src/panes/grid.rs
index b74966f3..4a569bb1 100644
--- a/zellij-server/src/panes/grid.rs
+++ b/zellij-server/src/panes/grid.rs
@@ -382,7 +382,7 @@ impl Grid {
             .horizontal_tabstops
             .iter()
             .copied()
-            .find(|&tabstop| tabstop > self.cursor.x);
+            .find(|&tabstop| tabstop > self.cursor.x && tabstop < self.width);
         match next_tabstop {
             Some(tabstop) => {
                 self.cursor.x = tabstop;
@@ -935,37 +935,22 @@ impl Grid {
     pub fn move_cursor_to_beginning_of_line(&mut self) {
         self.cursor.x = 0;
     }
-    pub fn insert_character_at_cursor_position(&mut self, terminal_character: TerminalCharacter) {
-        match self.viewport.get_mut(self.cursor.y) {
-            Some(row) => {
-                row.insert_character_at(terminal_character, self.cursor.x);
-                if row.width() > self.width {
-                    row.truncate(self.width);
-                }
-                self.output_buffer.update_line(self.cursor.y);
-            }
-            None => {
-                // pad lines until cursor if they do not exist
-                for _ in self.viewport.len()..self.cursor.y {
-                    self.viewport.push(Row::new(self.width).canonical());
-                }
-                self.viewport.push(
-                    Row::new(self.width)
-                        .with_character(terminal_character)
-                        .canonical(),
-                );
-                self.output_buffer.update_all_lines();
-            }
-        }
-    }
-    pub fn add_character_at_cursor_position(&mut self, terminal_character: TerminalCharacter) {
+    pub fn add_character_at_cursor_position(
+        &mut self,
+        terminal_character: TerminalCharacter,
+        should_insert_character: bool,
+    ) {
+        // this function assumes the current line has enough room for terminal_character (that its
+        // width has been checked beforehand)
         match self.viewport.get_mut(self.cursor.y) {
             Some(row) => {
-                if self.insert_mode {
+                if self.insert_mode || should_insert_character {
                     row.insert_character_at(terminal_character, self.cursor.x);
+                    if row.width() > self.width {
+                        row.truncate(self.width);
+                    }
                 } else {
                     row.add_character_at(terminal_character, self.cursor.x);
-                    // self.move_cursor_forward_until_edge(count_to_move_cursor);
                 }
                 self.output_buffer.update_line(self.cursor.y);
             }
@@ -984,7 +969,6 @@ impl Grid {
         }
     }
     pub fn add_character(&mut self, terminal_character: TerminalCharacter) {
-        // TODO: try to separate adding characters from moving the cursors in this function
         let character_width = terminal_character.width;
         if character_width == 0 {
             return;
@@ -993,28 +977,9 @@ impl Grid {
             if self.disable_linewrap {
                 return;
             }
-            // line wrap
-            self.cursor.x = 0;
-            if self.cursor.y == self.height - 1 {
-                if self.alternate_lines_above_viewport_and_cursor.is_none() {
-                    self.transfer_rows_to_lines_above(1);
-                } else {
-                    self.viewport.remove(0);
-                }
-                let wrapped_row = Row::new(self.width);
-                self.viewport.push(wrapped_row);
-                self.selection.move_up(1);
-                self.output_buffer.update_all_lines();
-            } else {
-                self.cursor.y += 1;
-                if self.viewport.len() <= self.cursor.y {
-                    let line_wrapped_row = Row::new(self.width);
-                    self.viewport.push(line_wrapped_row);
-                    self.output_buffer.update_line(self.cursor.y);
-                }
-            }
+            self.line_wrap();
         }
-        self.add_character_at_cursor_position(terminal_character);
+        self.add_character_at_cursor_position(terminal_character, false);
         self.move_cursor_forward_until_edge(character_width);
     }
     pub fn get_character_under_cursor(&self) -> Option<TerminalCharacter> {
@@ -1075,6 +1040,27 @@ impl Grid {
         }
         self.output_buffer.update_all_lines();
     }
+    fn line_wrap(&mut self) {
+        self.cursor.x = 0;
+        if self.cursor.y == self.height - 1 {
+            if self.alternate_lines_above_viewport_and_cursor.is_none() {
+                self.transfer_rows_to_lines_above(1);
+            } else {
+                self.viewport.remove(0);
+            }
+            let wrapped_row = Row::new(self.width);
+            self.viewport.push(wrapped_row);
+            self.selection.move_up(1);
+            self.output_buffer.update_all_lines();
+        } else {
+            self.cursor.y += 1;
+            if self.viewport.len() <= self.cursor.y {
+                let line_wrapped_row = Row::new(self.width);
+                self.viewport.push(line_wrapped_row);
+                self.output_buffer.update_line(self.cursor.y);
+            }
+        }
+    }
     fn clear_lines_above(&mut self) {
         self.lines_above.clear();
         self.scrollback_buffer_lines = self.recalculate_scrollback_buffer_count();
@@ -1546,8 +1532,8 @@ impl Perform for Grid {
             // Set color index.
             b"4" => {
                 for chunk in params[1..].chunks(2) {
-                    let index = parse_number(chunk[0]);
-                    let color = xparse_color(chunk[1]);
+                    let index = chunk.get(0).and_then(|index| parse_number(index));
+                    let color = chunk.get(1).and_then(|color| xparse_color(color));
                     if let (Some(i), Some(c)) = (index, color) {
                         if self.changed_colors.is_none() {
                             self.changed_colors = Some([None; 256]);
@@ -1893,6 +1879,7 @@ impl Perform for Grid {
             self.add_empty_lines_in_scroll_region(line_count_to_add, pad_character);
         } else if c == 'G' || c == '`' {
             let column = next_param_or(1).saturating_sub(1);
+            let column = std::cmp::min(column, self.width.saturating_sub(1));
             self.move_cursor_to_column(column);
         } else if c == 'g' {
             let clear_type = next_param_or(0);
@@ -1933,8 +1920,9 @@ impl Perform for Grid {
         } else if c == '@' {
             let count = next_param_or(1);
             for _ in 0..count {
-                // TODO: should this be styled?
-                self.insert_character_at_cursor_position(EMPTY_TERMINAL_CHARACTER);
+                let mut pad_character = EMPTY_TERMINAL_CHARACTER;
+                pad_character.styles = self.cursor.pending_styles;
+                self.add_character_at_cursor_position(pad_character, true);
             }
         } else if c == 'b' {
             if let Some(c) = self.preceding_char {
@@ -2327,9 +2315,10 @@ impl Row {
             self.columns.push_back(terminal_character);
             // this is much more performant than remove/insert
             let character = self.columns.swap_remove_back(absolute_x_index).unwrap();
-            let excess_width = character.width.saturating_sub(1);
+            let excess_width = character.width.saturating_sub(terminal_character.width);
             for _ in 0..excess_width {
-                self.columns.insert(absolute_x_index, terminal_character);
+                self.columns
+                    .insert(absolute_x_index, EMPTY_TERMINAL_CHARACTER);
             }
         }
         self.width = None;
@@ -2417,17 +2406,6 @@ impl Row {
         self.width = None;
         self.columns = replace_with;
     }
-    pub fn replace_beginning_with(&mut self, mut line_part: VecDeque<TerminalCharacter>) {
-        // this assumes line_part has no wide characters
-        if line_part.len() > self.columns.len() {
-            self.columns.clear();
-        } else {
-            drop(self.columns.drain(0..line_part.len()));
-        }
-        line_part.append(&mut self.columns);
-        self.width = None;
-        self.columns = line_part;
-    }
     pub fn len(&self) -> usize {
         self.columns.len()
     }
diff --git a/zellij-server/src/panes/unit/grid_tests.rs b/zellij-server/src/panes/unit/grid_tests.rs
index b0e00f9a..eac87284 100644
--- a/zellij-server/src/panes/unit/grid_tests.rs
+++ b/zellij-server/src/panes/unit/grid_tests.rs
@@ -1792,3 +1792,20 @@ fn terminal_pixel_size_reports_in_unsupported_terminals() {
         expected,
     );
 }
+
+#[test]
+pub fn ansi_csi_at_sign() {
+    let mut vte_parser = vte::Parser::new();
+    let mut grid = Grid::new(
+        51,
+        112,
+        Palette::default(),
+        Rc::new(RefCell::new(LinkHandler::new())),
+        Rc::new(RefCell::new(None)),
+    );
+    let content = "foo\u{1b}[2D\u{1b}[2@".as_bytes();
+    for byte in content {
+        vte_parser.advance(&mut grid, *byte);
+    }
+    assert_snapshot!(format!("{:?}", grid));
+}
diff --git a/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__ansi_csi_at_sign.snap b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__ansi_csi_at_sign.snap
new file mode 100644
index 00000000..12ec5d49
--- /dev/null
+++ b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__ansi_csi_at_sign.snap
@@ -0,0 +1,7 @@
+---
+source: zellij-server/src/panes/./unit/grid_tests.rs
+assertion_line: 1810
+expression: "format!(\"{:?}\", grid)"
+---
+00 (C): f  oo
+
diff --git a/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_1.snap b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_1.snap
index 4381306b..3e4ded7a 100644
--- a/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_1.snap
+++ b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_1.snap
@@ -1,9 +1,9 @@
 ---
 source: zellij-server/src/panes/./unit/grid_tests.rs
+assertion_line: 447
 expression: "format!(\"{:?}\", grid)"
-
 ---
-00 (C): A******************************************************************************BAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA                 
+00 (C): A******************************************************************************BAAAAAAAAAAAAAAAAA
 01 (C):                                                                                                  
 02 (C):                                                                                                  
 03 (C): Test of 'Insert Mode'. The top line should be 'A*** ... ***B'. Push <RETURN>                     
diff --git a/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_2.snap b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_2.snap
index 6d60398e..f319d10b 100644
--- a/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_2.snap
+++ b/zellij-server/src/panes/unit/snapshots/zellij_server__panes__grid__grid_tests__vttest8_2.snap
@@ -1,9 +1,9 @@
 ---
 source: zellij-server/src/panes/./unit/grid_tests.rs
+assertion_line: 465
 expression: "format!(\"{:?}\", grid)"
-
 ---
-00 (C): ABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA                 
+00 (C): ABAAAAAAAAAAAAAAAAA
 01 (C):                                                                                                  
 02 (C):                                                                                                  
 03 (C): Test of 'Delete Character'. The top line should be 'AB'. Push <RETURN>