[PATCH v2 29/45] image: Correct strncpy() warning with image_set_name()

[Heinrich Schuchardt]

On 10/13/22 14:29, Simon Glass wrote:
> gcc 12 seems to warn on strncpy() as a matter of course. Rewrite the code
> a different way to do the same thing, to avoid the warning.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> (no changes since v1)
>
>   include/image.h | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/image.h b/include/image.h
> index 7c91e705bf1..a8fd3e34287 100644
> --- a/include/image.h
> +++ b/include/image.h
> @@ -853,7 +853,13 @@ image_set_hdr_b(comp)		/* image_set_comp */
>
>   static inline void image_set_name(struct legacy_img_hdr *hdr, const char *name)
>   {
> -	strncpy(image_get_name(hdr), name, IH_NMLEN);
> +	/*
> +	 * This is equivalent to: strncpy(image_get_name(hdr), name, IH_NMLEN);
> +	 *
> +	 * Use the tortured code below to avoid a warning with gcc 12. We do not
> +	 * want to include a nul terminator if the name is of length IH_NMLEN
> +	 */
> +	memcpy(image_get_name(hdr), name, strnlen(name, IH_NMLEN));
>   }
>
>   int image_check_hcrc(const struct legacy_img_hdr *hdr);

memcpy does not add a trailing '\0' if there is enough space.

In a parallel thread today it was indicated that the proper way of
addressing the problem is using __attribute__(nonstring), cf.

https://lore.kernel.org/u-boot/dad17a9f-d823-1e8b-3381-53961294521c@prevas.dk/

Best regards

Heinrich