[Spice-devel] [PATCH] macros: make SPICE_CONTAINEROF more typesafe

[Frediano Ziglio]

Check the pointer given is the same type as member pointer.

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 spice/macros.h | 6 ++++++
 1 file changed, 6 insertions(+)


Note that some spice-server need some update in order to compile after
this macro change.


diff --git a/spice/macros.h b/spice/macros.h
index cd63528..2efbaff 100644
--- a/spice/macros.h
+++ b/spice/macros.h
@@ -143,8 +143,14 @@
     ((long) ((uint8_t*) &((struct_type*) 0)->member))
 #endif
 
+#if    __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+#define SPICE_CONTAINEROF(ptr, struct_type, member) ({ \
+    const typeof( ((struct_type *)0)->member ) *__mptr = (ptr);    \
+    ((struct_type *)(void *)((uint8_t *)(__mptr) - SPICE_OFFSETOF(struct_type, member))); })
+#else
 #define SPICE_CONTAINEROF(ptr, struct_type, member) \
     ((struct_type *)(void *)((uint8_t *)(ptr) - SPICE_OFFSETOF(struct_type, member)))
+#endif
 
 #define SPICE_MEMBER_P(struct_p, struct_offset)   \
     ((gpointer) ((guint8*) (struct_p) + (glong) (struct_offset)))
-- 
2.4.3