linux-kernel - Re: [PATCH 3/6] lib80211: re-use string_escape_mem_any

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Date:	Wed, 02 Jul 2014 06:43:31 -0700
From:	Joe Perches <joe@...ches.com>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	"John W. Linville" <linville@...driver.com>,
	Johannes Berg <johannes@...solutions.net>,
	devel@...verdev.osuosl.org, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 3/6] lib80211: re-use string_escape_mem_any_np()

On Wed, 2014-07-02 at 16:20 +0300, Andy Shevchenko wrote:
> In kernel we have function to escape a given string. Let's use it instead of
> custom approach.
> 
> This fixes a bug. The current implementation wrongly prints octal numbers: only
> two first digits are used in case when 3 are required and the rest of the
> string ends up cut off.
[]
> diff --git a/net/wireless/lib80211.c b/net/wireless/lib80211.c
[]
> @@ -48,31 +49,10 @@ static void lib80211_crypt_deinit_handler(unsigned long data);
>  
>  const char *print_ssid(char *buf, const char *ssid, u8 ssid_len)
>  {
> -	const char *s = ssid;
>  	char *d = buf;
>  
>  	ssid_len = min_t(u8, ssid_len, IEEE80211_MAX_SSID_LEN);
> -	while (ssid_len--) {
> -		if (isprint(*s)) {
> -			*d++ = *s++;
> -			continue;
> -		}
> -
> -		*d++ = '\\';
> -		if (*s == '\0')
> -			*d++ = '0';
> -		else if (*s == '\n')
> -			*d++ = 'n';
> -		else if (*s == '\r')
> -			*d++ = 'r';
> -		else if (*s == '\t')
> -			*d++ = 't';
> -		else if (*s == '\\')
> -			*d++ = '\\';
> -		else
> -			d += snprintf(d, 3, "%03o", *s);
> -		s++;
> -	}
> +	d += string_escape_mem_any_np(ssid, ssid_len, buf, ~0UL, NULL);
>  	*d = '\0';
>  	return buf;
>  }

This code looks like it was adapted from the old print_mac
ethernet code that was eventually replaced by a vsprintf
pointer extension %pM

So a better way to do this might be to add and use yet
another vsprintf %p<foo> extension for ssids.


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