Re: [Xen-devel] [PATCH V3 4/8] xen/common: Introduce xrealloc_flex_struct() helper macros

[Jan Beulich <jbeulich@xxxxxxxx>]

On 28.08.2019 20:23, Oleksandr wrote:
> --- a/xen/include/xen/xmalloc.h
> +++ b/xen/include/xen/xmalloc.h
> @@ -35,6 +35,18 @@
>   #define xzalloc_array(_type, _num) \
>       ((_type *)_xzalloc_array(sizeof(_type), __alignof__(_type), _num))
> 
> +/* Allocate space for a structure with a flexible array of typed 
> objects. */
> +#define xmalloc_flex_struct(type, field, nr) \
> +    ((type *)_xmalloc(offsetof(type, field[nr]), __alignof__(type)))
> +
> +/* Re-allocate space for a structure with a flexible array of typed 
> objects. */
> +#define xrealloc_flex_struct(ptr, type, field, nr) 
> ({                        \
> +    typeof(*(ptr)) *ptr_ = 
> (ptr);                                            \
> +    /* Type checking: make sure that incoming pointer is of correct 
> type */  \
> +    (void)((ptr) == (type 
> *)0);                                              \
> +    (type *)_xrealloc(ptr_, offsetof(type, field[nr]), 
> __alignof__(type));   \
> +})
> +

What about

#define xrealloc_flex_struct(ptr, field, nr)                         \
    (typeof(ptr))_xrealloc(ptr, offsetof(typeof(*(ptr)), field[nr]), \
                           __alignof__(typeof(*(ptr))))

?

Jan

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