efl_ui/box: avoid exploding stack with lots of subobjects

using alloca like this without any limits is dangerous, so switch to
malloc here in such cases

Reviewed-by: Cedric BAIL <cedric.bail@free.fr>
Differential Revision: https://phab.enlightenment.org/D9341

diff --git a/src/lib/elementary/efl_ui_box_layout.c b/src/lib/elementary/efl_ui_box_layout.c
index eede41e..d45532d 100644 (file)
--- a/src/lib/elementary/efl_ui_box_layout.c
+++ b/src/lib/elementary/efl_ui_box_layout.c
@@ -52,7 +52,16 @@ _efl_ui_box_custom_layout(Efl_Ui_Box *ui_box, Efl_Ui_Box_Data *pd)
 
    _efl_ui_container_layout_init(ui_box, box_calc);
 
-   items = alloca(count * sizeof(*items));
+   /* Item_Calc struct is currently 152 bytes.
+    * this is pretty big to be allocating a huge number of, and we don't want to explode the stack
+    */
+   if (count >= 500)
+     {
+        items = malloc(count * sizeof(*items));
+        EINA_SAFETY_ON_NULL_RETURN(items);
+     }
+   else
+     items = alloca(count * sizeof(*items));
 #ifdef DEBUG
    memset(items, 0, count * sizeof(*items));
 #endif
@@ -201,4 +210,5 @@ _efl_ui_box_custom_layout(Efl_Ui_Box *ui_box, Efl_Ui_Box_Data *pd)
    efl_gfx_hint_size_restricted_min_set(ui_box, EINA_SIZE2D(want[0], want[1]));
 
    efl_event_callback_call(ui_box, EFL_PACK_EVENT_LAYOUT_UPDATED, NULL);
+   if (count >= 500) free(items);
 }