Merge pull request #9079 from bfredl/tui_cursor

TUI cursor fixes: avoid memory errors after resize with invalid cursor position

src/nvim/tui/tui.c

@@ -88,7 +88,6 @@ typedef struct {
   bool cont_received;
   UGrid grid;
   kvec_t(Rect) invalid_regions;
-  bool did_resize;
   int row, col;
   int out_fd;
   bool scroll_region_is_full_screen;
@@ -577,7 +576,7 @@ static void final_column_wrap(UI *ui)
 {
   TUIData *data = ui->data;
   UGrid *grid = &data->grid;
-  if (grid->col == ui->width) {
+  if (grid->row != -1 && grid->col == ui->width) {
     grid->col = 0;
     if (grid->row < MIN(ui->height, grid->height - 1)) {
       grid->row++;
@@ -647,6 +646,9 @@ static void cursor_goto(UI *ui, int row, int col)
     ugrid_goto(grid, row, col);
     return;
   }
+  if (grid->row == -1) {
+    goto safe_move;
+  }
   if (0 == col ? col != grid->col :
       row != grid->row ? false :
       1 == col ? 2 < grid->col && cheap_to_print(ui, grid->row, 0, col) :
@@ -725,6 +727,8 @@ static void cursor_goto(UI *ui, int row, int col)
       return;
     }
   }
+
+safe_move:
   unibi_goto(ui, row, col);
   ugrid_goto(grid, row, col);
 }
@@ -773,20 +777,9 @@ static void clear_region(UI *ui, int top, int bot, int left, int right,
       cursor_goto(ui, row, col);
       print_cell(ui, cell);
     });
-
-    if (data->did_resize && top == 0) {
-      // TODO(bfredl): the first line of the screen doesn't gets properly
-      // cleared after resize by the loop above, so redraw the final state
-      // after the next flush.
-      invalidate(ui, 0, bot, left, right);
-      data->did_resize = false;
   }
 }
 
-  // restore cursor
-  cursor_goto(ui, data->row, data->col);
-}
-
 static void set_scroll_region(UI *ui, int top, int bot, int left, int right)
 {
   TUIData *data = ui->data;
@@ -808,7 +801,7 @@ static void set_scroll_region(UI *ui, int top, int bot, int left, int right)
       unibi_out(ui, unibi_set_right_margin_parm);
     }
   }
-  unibi_goto(ui, grid->row, grid->col);
+  grid->row = -1;
 }
 
 static void reset_scroll_region(UI *ui, bool fullwidth)
@@ -836,7 +829,7 @@ static void reset_scroll_region(UI *ui, bool fullwidth)
     }
     unibi_out_ext(ui, data->unibi_ext.disable_lr_margin);
   }
-  unibi_goto(ui, grid->row, grid->col);
+  grid->row = -1;
 }
 
 static void tui_grid_resize(UI *ui, Integer g, Integer width, Integer height)
@@ -844,7 +837,6 @@ static void tui_grid_resize(UI *ui, Integer g, Integer width, Integer height)
   TUIData *data = ui->data;
   UGrid *grid = &data->grid;
   ugrid_resize(grid, (int)width, (int)height);
-  data->did_resize = true;
 
   // resize might not always be followed by a clear before flush
   // so clip the invalid region
@@ -864,6 +856,7 @@ static void tui_grid_resize(UI *ui, Integer g, Integer width, Integer height)
     }
   } else {  // Already handled the SIGWINCH signal; avoid double-resize.
     got_winch = false;
+    grid->row = -1;
   }
 }
 
@@ -880,9 +873,10 @@ static void tui_grid_clear(UI *ui, Integer g)
 static void tui_grid_cursor_goto(UI *ui, Integer grid, Integer row, Integer col)
 {
   TUIData *data = ui->data;
+
+  // cursor position is validated in tui_flush
   data->row = (int)row;
   data->col = (int)col;
-  cursor_goto(ui, (int)row, (int)col);
 }
 
 CursorShape tui_cursor_decode_shape(const char *shape_str)
@@ -1070,7 +1064,6 @@ static void tui_grid_scroll(UI *ui, Integer g, Integer startrow, Integer endrow,
     if (!data->scroll_region_is_full_screen) {
       reset_scroll_region(ui, fullwidth);
     }
-    cursor_goto(ui, data->row, data->col);
 
     if (!(data->bce || no_bg(ui, data->clear_attrs))) {
       // Scrolling will leave wrong background in the cleared area on non-BCE

src/nvim/ugrid.c

@@ -32,7 +32,6 @@ void ugrid_resize(UGrid *grid, int width, int height)
     grid->cells[i] = xcalloc((size_t)width, sizeof(UCell));
   }
 
-  grid->row = grid->col = 0;
   grid->width = width;
   grid->height = height;
 }

test/functional/terminal/tui_spec.lua

@@ -17,7 +17,6 @@ local nvim_prog = helpers.nvim_prog
 local nvim_set = helpers.nvim_set
 local ok = helpers.ok
 local read_file = helpers.read_file
-local wait = helpers.wait
 
 if helpers.pending_win32(pending) then return end
 
@@ -473,14 +472,24 @@ describe("tui 't_Co' (terminal colors)", function()
       nvim_prog,
       nvim_set))
 
-    feed_data(":echo &t_Co\n")
-    wait()
     local tline
     if maxcolors == 8 or maxcolors == 16 then
       tline = "~                                                 "
     else
       tline = "{4:~                                                 }"
     end
+
+    screen:expect(string.format([[
+      {1: }                                                 |
+      %s|
+      %s|
+      %s|
+      %s|
+                                                        |
+      {3:-- TERMINAL --}                                    |
+    ]], tline, tline, tline, tline))
+
+    feed_data(":echo &t_Co\n")
     screen:expect(string.format([[
       {1: }                                                 |
       %s|