fix(bar): 修复 bar_cell_t text 字段可能为野指针 bug

src/bar/bar.c

@@ -33,6 +33,11 @@ static void bar_item_cleanup(zdwm_bar_item_t *item) {
   if (destroy_state) destroy_state(item->state);
   item->state = nullptr;
 
+  for (size_t i = 0; i < item->count; ++i) {
+    auto cell = &item->cells[i];
+    p_delete(&cell->text);
+  }
+
   p_delete(&item->cells);
   p_clear(item, 1);
 }

src/bar/cell.c

@@ -68,9 +68,11 @@ void bar_cell_set_text(zdwm_bar_item_t *item, size_t index, const char *text) {
   if (index >= item->count) return;
 
   auto cell = &item->cells[index];
-  if (cell->text == text || strcmp(cell->text, text) == 0) return;
+  if (cell->text && text && strcmp(cell->text, text) == 0) return;
 
-  cell->text = text;
+  p_delete(&cell->text);
+
+  cell->text = p_strdup_nullable(text);
 
   cell->dirty = true;
   item->dirty = true;

src/bar/types.h

@@ -14,7 +14,7 @@ typedef struct bar_x_region_t {
 
 typedef struct bar_cell_t {
   zdwm_icon_t icon;
-  const char *text;
+  char *text; /* 持有内存，避免野指针问题 */
   const color_t *fg;
   const color_t *bg;
   bar_x_region_t region;