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

[Jonathon Jongsma]

On Thu, 2015-12-03 at 15:28 +0000, Frediano Ziglio wrote:
> Check the pointer given is the same type as member pointer.
> 

maybe mention here that this uses a gcc extension: 
https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html


> 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.

Did it uncover some bugs, or?


> 
> 
> 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)))


Acked-by: Jonathon Jongsma <jjongsma at redhat.com>