Re: [PATCH] darray: Fix bug in the darray_remove() macro

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On Mon, Aug 28, 2017 at 07:09:35AM +0200, Damien Grassart wrote:
> The memmove() call should be using the index argument to determine the
> number of bytes to copy. To be consistent with the rest of the code,
> we should also not evaluate the index parameter multiple
> times. Calling this with rand() % arr.size would otherwise generally
> segfault.
>=20
> Finally, we want to avoid using "index" as an identifier so as to not
> shadow index(3) in the C library.

Uh.. sorry, I think we're in a state of confusion because applied some
of the patches then removed them again due to problems discovered
later.

Can you please rebase on the latest ccan tree and send me the whole
set of patches as a batch.

>=20
> Signed-off-by: Damien Grassart <[email protected]>
> ---
>  ccan/darray/darray.h | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
>=20
> diff --git a/ccan/darray/darray.h b/ccan/darray/darray.h
> index 82726c05..58470fde 100644
> --- a/ccan/darray/darray.h
> +++ b/ccan/darray/darray.h
> @@ -170,8 +170,8 @@ typedef darray(unsigned long)  darray_ulong;
>  		memmove((arr).item+1, (arr).item, ((arr).size-1)*sizeof(*(arr).item));=
 \
>  		(arr).item[0] =3D (__VA_ARGS__); \
>  	} while(0)
> -#define darray_insert(arr, index, ...) do { \
> -		size_t index_ =3D index; \
> +#define darray_insert(arr, i, ...) do { \
> +		size_t index_ =3D (i); \
>  		darray_resize(arr, (arr).size+1); \
>  		memmove((arr).item+index_+1, (arr).item+index_, ((arr).size-index_-1)*=
sizeof(*(arr).item)); \
>  		(arr).item[index_] =3D (__VA_ARGS__); \
> @@ -230,9 +230,10 @@ typedef darray(unsigned long)  darray_ulong;
>  #define darray_pop(arr) ((arr).item[--(arr).size])
>  #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-i)*siz=
eof(*(arr).item)); \
> +#define darray_remove(arr, i) do { \
> +	size_t index_ =3D (i); \
> +	if (index_ < arr.size-1)    \
> +		memmove(&(arr).item[index_], &(arr).item[index_+1], ((arr).size-1-inde=
x_)*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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