GClosure: add valgrind hints

GClosure has been in the "allocate area before the pointer" game since
before we did this with GTypeInstance.  At the time that this was done
for GClosure, we didn't have valgrind.h in GLib.

Now that we do, we should add similar valgrind hints as the ones we did
for GTypeInstance.  This substantially reduces reports of "possibly
lost" on pretty much any program that makes use of signals.

https://bugzilla.gnome.org/show_bug.cgi?id=739850

diff --git a/gobject/gclosure.c b/gobject/gclosure.c
index 33353bb..014e40a 100644 (file)
--- a/gobject/gclosure.c
+++ b/gobject/gclosure.c
@@ -22,6 +22,7 @@
 
 #include "config.h"
 
+#include "../glib/valgrind.h"
 #include <string.h>
 
 #include <ffi.h>
@@ -189,14 +190,31 @@ GClosure*
 g_closure_new_simple (guint           sizeof_closure,
                      gpointer        data)
 {
-  GRealClosure *real_closure;
   GClosure *closure;
+  gint private_size;
+  gchar *allocated;
 
   g_return_val_if_fail (sizeof_closure >= sizeof (GClosure), NULL);
-  sizeof_closure = sizeof_closure + sizeof (GRealClosure) - sizeof (GClosure);
 
-  real_closure = g_malloc0 (sizeof_closure);
-  closure = &real_closure->closure;
+  private_size = sizeof (GRealClosure) - sizeof (GClosure);
+
+  /* See comments in gtype.c about what's going on here... */
+  if (RUNNING_ON_VALGRIND)
+    {
+      private_size += sizeof (gpointer);
+
+      allocated = g_malloc0 (private_size + sizeof_closure + sizeof (gpointer));
+
+      *(gpointer *) (allocated + private_size + sizeof_closure) = allocated + sizeof (gpointer);
+
+      VALGRIND_MALLOCLIKE_BLOCK (allocated + private_size, sizeof_closure + sizeof (gpointer), 0, TRUE);
+      VALGRIND_MALLOCLIKE_BLOCK (allocated + sizeof (gpointer), private_size - sizeof (gpointer), 0, TRUE);
+    }
+  else
+    allocated = g_malloc0 (private_size + sizeof_closure);
+
+  closure = (GClosure *) (allocated + private_size);
+
   SET (closure, ref_count, 1);
   SET (closure, floating, TRUE);
   closure->data = data;
@@ -589,7 +607,22 @@ g_closure_unref (GClosure *closure)
     {
       closure_invoke_notifiers (closure, FNOTIFY);
       g_free (closure->notifiers);
-      g_free (G_REAL_CLOSURE (closure));
+
+      /* See comments in gtype.c about what's going on here... */
+      if (RUNNING_ON_VALGRIND)
+        {
+          gchar *allocated;
+
+          allocated = (gchar *) G_REAL_CLOSURE (closure);
+          allocated -= sizeof (gpointer);
+
+          g_free (allocated);
+
+          VALGRIND_FREELIKE_BLOCK (allocated + sizeof (gpointer), 0);
+          VALGRIND_FREELIKE_BLOCK (closure, 0);
+        }
+      else
+        g_free (G_REAL_CLOSURE (closure));
     }
 }