From: Christian Schulte <cs@schulte.it>
Subject: Re: new warning in make
To: millert@openbsd.org, tech@openbsd.org
Date: Fri, 26 Sep 2025 11:03:56 +0200

Am 25.09.2025 um 11:35 schrieb Marc Espie:
> cc now warns over arch.c
> /usr/src/usr.bin/make/arch.c:839:3: warning: 'snprintf' will always be truncated; specified size is 12, but format string expands to at least 13 [-Wformat-truncation]
>   839 |                 snprintf(arHeader.ar_date, sizeof(arHeader.ar_date),
>       |                 ^
> 
> 
> Pretty sure it's correct, considering that snprintf will truncate with a 0.
> 
> Printing to a temp buffer and copying only the string ought to fix it
> if I'm not mistaken.
> 
> Index: arch.c
> ===================================================================
> RCS file: /vide/cvs/src/usr.bin/make/arch.c,v
> diff -u -p -r1.94 arch.c
> --- arch.c	4 Sep 2023 11:35:11 -0000	1.94
> +++ arch.c	25 Sep 2025 09:33:07 -0000
> @@ -836,8 +836,9 @@ ArchTouch(const char *archive, const cha
>  
>  	arch = ArchFindMember(archive, member, &arHeader, "r+");
>  	if (arch != NULL) {
> -		snprintf(arHeader.ar_date, sizeof(arHeader.ar_date),
> -		    "%-12ld", (long) time(NULL));
> +		char temp[sizeof(arHeader.ar_date)+1];
> +		snprintf(temp, sizeof(temp), "%-12ld", (long) time(NULL));

I am really not sure but I think this should read "%-12" PRIdMAX,
(intmax_t)time(NULL));

Just my 2 cents.

-- 
Christian