linux-kernel - Re: [PATCH 12/24] getgrent_r.3: Use sizeof() to get buffer size (instead of hardcoding macro name)

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Date:   Fri, 11 Sep 2020 17:35:28 +0300
From:   Stefan Puiu <stefan.puiu@...il.com>
To:     Alejandro Colomar <colomar.6.4.3@...il.com>
Cc:     Michael Kerrisk <mtk.manpages@...il.com>,
        lnx-man <linux-man@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/24] getgrent_r.3: Use sizeof() to get buffer size
 (instead of hardcoding macro name)

Hi,

On Fri, Sep 11, 2020 at 12:15 AM Alejandro Colomar
<colomar.6.4.3@...il.com> wrote:
>
> Signed-off-by: Alejandro Colomar <colomar.6.4.3@...il.com>
> ---
>  man3/getgrent_r.3 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/man3/getgrent_r.3 b/man3/getgrent_r.3
> index 81d81a851..76deec370 100644
> --- a/man3/getgrent_r.3
> +++ b/man3/getgrent_r.3
> @@ -186,7 +186,7 @@ main(void)
>
>      setgrent();
>      while (1) {
> -        i = getgrent_r(&grp, buf, BUFLEN, &grpp);
> +        i = getgrent_r(&grp, buf, sizeof(buf), &grpp);

I'm worried that less attentive people might copy/paste parts of this
in their code, where maybe buf is just a pointer, and expect it to
work. Maybe leaving BUFLEN here is useful as a reminder that they need
to change something to adapt the code?

Just my 2 cents,
Stefan.