[vlc-commits] Avoid arithmetic on NULL in VLC_OBJECT() kludge-macro

[Rémi Denis-Courmont]

vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Sat May 12 23:40:32 2018 +0300| [b8c7cf13e274d58574c4574b44233a67a3e91450] | committer: Rémi Denis-Courmont

Avoid arithmetic on NULL in VLC_OBJECT() kludge-macro

If the offset of b within a is zero, then (&(a)->b) is equivalent to
casting a to a pointer to the type of the b member. However this implies
that a is a valid pointer. The expression is not valid if a is NULL.

Especially sanitizers do not like this.

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=b8c7cf13e274d58574c4574b44233a67a3e91450
---

 include/vlc_objects.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/vlc_objects.h b/include/vlc_objects.h
index 8a107dbfad..f619936504 100644
--- a/include/vlc_objects.h
+++ b/include/vlc_objects.h
@@ -85,11 +85,10 @@ struct vlc_common_members
 #if !defined(__cplusplus)
 # define VLC_OBJECT(x) \
     _Generic((x)->obj, \
-        struct vlc_common_members: (vlc_object_t *)(&(x)->obj), \
-        const struct vlc_common_members: (const vlc_object_t *)(&(x)->obj) \
+        struct vlc_common_members: (vlc_object_t *)(x) \
     )
 #else
-# define VLC_OBJECT( x ) ((vlc_object_t *)&(x)->obj)
+# define VLC_OBJECT(x) ((vlc_object_t *)(x))
 #endif
 
 /* Object flags */