constraints: fix mem leak in meta_window_constrain()

MetaFrameBorders leaked when orig_borders != NULL and
window->fullscreen == TRUE

https://bugzilla.gnome.org/show_bug.cgi?id=679153

upstream commit:
https://gitlab.gnome.org/GNOME/metacity/commit/7e7f25f4

1 files changed, 10 insertions, 3 deletions

diff --git a/src/core/constraints.c b/src/core/constraints.c
index 8f7e0d7e..c886d927 100644
--- a/src/core/constraints.c
+++ b/src/core/constraints.c
@@ -118,6 +118,7 @@ typedef struct
   MetaRectangle        orig;
   MetaRectangle        current;
   MetaFrameBorders    *borders;
+  gboolean             must_free_borders;
   ActionType           action_type;
   gboolean             is_user_action;
 
@@ -339,7 +340,7 @@ meta_window_constrain (MetaWindow          *window,
    * not gobject-style--gobject would be more pain than it's worth) or
    * smart pointers would be so much nicer here.  *shrug*
    */
-  if (!orig_borders)
+  if (info.must_free_borders)
     g_free (info.borders);
 }
 
@@ -360,9 +361,15 @@ setup_constraint_info (ConstraintInfo      *info,
 
   /* Create a fake frame geometry if none really exists */
   if (orig_borders && !window->fullscreen)
-    info->borders = orig_borders;
+    {
+      info->borders = orig_borders;
+      info->must_free_borders = FALSE;
+    }
   else
-    info->borders = g_new0 (MetaFrameBorders, 1);
+    {
+      info->borders = g_new0 (MetaFrameBorders, 1);
+      info->must_free_borders = TRUE;
+    }
 
   if (flags & META_IS_MOVE_ACTION && flags & META_IS_RESIZE_ACTION)
     info->action_type = ACTION_MOVE_AND_RESIZE;