linux-kernel - Re: [PATCH] vsprintf: automatic parameters for %pIS via 'a'

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Date:	Wed, 03 Feb 2016 15:05:21 -0800
From:	Joe Perches <joe@...ches.com>
To:	"Jason A. Donenfeld" <Jason@...c4.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux@...musvillemoes.dk, andriy.shevchenko@...ux.intel.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] vsprintf: automatic parameters for %pIS via 'a'

On Wed, 2016-02-03 at 23:53 +0100, Jason A. Donenfeld wrote:
> This patch adds a variable 'a' which indicates that the 'p',
> 'f', and 's' options should be toggled on or off depending on
> whether or not those parameters are actually valid inside the
> passed sockaddr.

OK

> This is something that probably most users of
> the %pIS family of functions will prefer to use.

More doubtful.

There isn't a single user of flowinfo or scope today.

These are the current uses of %pIS

      8 %pIS
     11 %pISc
      5 %pIScp
      2 %pISp
     23 %pISpc

> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
[]
> @@ -1169,9 +1169,18 @@ char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
>  		case 'c':
>  			have_c = true;
>  			break;
> +		case 'a':
> +			have_a = true;
> +			break;
>  		}
>  	}
>  
> +	if (have_a) {
> +		have_p = sa->sin6_port != 0;
> +		have_s = sa->sin6_scope_id != 0;
> +		have_f = sa->sin6_flowinfo != 0;

Doesn't this needs the mask tested?

		sa->sin6_flowinfo & IPV6_FLOWINFO_MASK

given the use of bool, the != 0 are unnecessary.

Other than that, looks good to me.