[glib] GClosure: add valgrind hints

[Ryan Lortie <desrt src gnome org>]

commit 69fd1fd1d0f110800ec713bac5dafb418ceecc1c
Author: Ryan Lortie <desrt desrt ca>
Date:   Sun Nov 9 11:22:42 2014 -0500

    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

 gobject/gclosure.c |   43 ++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 38 insertions(+), 5 deletions(-)
---
diff --git a/gobject/gclosure.c b/gobject/gclosure.c
index 33353bb..014e40a 100644
--- 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));
     }
 }