Re: [PATCH 2/2] darray: Evaluate the index parameter only once in darray_remove()

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On Sat, Aug 26, 2017 at 06:26:52PM +0200, Damien Grassart wrote:
> To be consistent with the rest of the code, the index paramater should
> not be evaluated multiple times. Calling this with rand() % arr.size
> would otherwise generally segfault.
> ---
>  ccan/darray/darray.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Looks like a definite improvement, but I need a Signed-off-by line in
order to apply it.

Also.. identifiers starting with _ are technically reserved for system
use.  You'd probably get away with it, but it's best to avoid them.  I
usually put _ after the name instead for this sort of thing.

>=20
> diff --git a/ccan/darray/darray.h b/ccan/darray/darray.h
> index 8d47645b..6dd34f08 100644
> --- a/ccan/darray/darray.h
> +++ b/ccan/darray/darray.h
> @@ -224,8 +224,9 @@ typedef darray(unsigned long)  darray_ulong;
>  #define darray_pop_check(arr) ((arr).size ? darray_pop(arr) : NULL)
>  /* Warning, slow: Requires copying all elements after removed item. */
>  #define darray_remove(arr, index) do { \
> -	if (index < arr.size-1)    \
> -		memmove(&(arr).item[index], &(arr).item[index+1], ((arr).size-1-index)=
*sizeof(*(arr).item)); \
> +	size_t __index =3D index; \
> +	if (__index < arr.size-1)    \
> +		memmove(&(arr).item[__index], &(arr).item[__index+1], ((arr).size-1-__=
index)*sizeof(*(arr).item)); \
>  	(arr).size--;  \
>  	} while(0)
> =20

--=20
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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