[Pkg-shadow-devel] Bug#1032393: Bug#1032393: [PATCH v2 2/2] debian/control: Add libbsd-dev and pkg-config

[Alejandro Colomar]

Hi Paul,

On 3/11/23 20:29, Paul Eggert wrote:
> From d40e2f92f3e50d13d87393bd30b2b4b20b89a2d6 Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert at cs.ucla.edu>
> Date: Sat, 11 Mar 2023 00:01:02 -0800
> Subject: [PATCH 1/6] Fix undefined behavior in change_field
> 
> * lib/fields.c (change_field): Do not ever compute &newf[-1],
> as behavior is undefined.  Since we know that the string fits,
> use memcpy rather than strlcpy.

I'd separate the UB fix, from the transformation to memcpy(3),
in two separate commits, since they are conceptually unrelated.

> 
> Signed-off-by: Paul Eggert <eggert at cs.ucla.edu>
> ---
>  lib/fields.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/fields.c b/lib/fields.c
> index 0b5f91b2..3b119502 100644
> --- a/lib/fields.c
> +++ b/lib/fields.c
> @@ -90,17 +90,17 @@ void change_field (char *buf, size_t maxsize, const char *prompt)
>  		 * makes it possible to change the field to empty, by
>  		 * entering a space.  --marekm
>  		 */
> +		char *bp = newf;
>  
> -		while (--cp >= newf && isspace (*cp));
> -		cp++;
> +		while (newf < cp && isspace (cp[-1])) {
> +			cp--;
> +		}
>  		*cp = '\0';
>  
> -		cp = newf;
> -		while (('\0' != *cp) && isspace (*cp)) {
> -			cp++;
> +		while (isspace (*bp)) {
> +			bp++;
>  		}
>  
> -		strlcpy (buf, cp, maxsize);
> +		memcpy (buf, bp, cp + 1 - bp);

Regarding this transformation, I'd prefer transforming to strcpy(3).
It avoids the manual `cp + 1 - bp` calculation.

Thanks for the review and patches!

Cheers,
Alex

>  	}
>  }
> -
> -- 
> 2.37.2
> 


-- 
<http://www.alejandro-colomar.es/>
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