netdev - Re: [RFC PATCH] vsprintf: Add %p*D extension for 80211 SSIDs

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Date:	Mon, 07 Jan 2013 14:07:14 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Joe Perches <joe@...ches.com>
CC:	"John W. Linville" <linville@...driver.com>,
	stas.yakovlev@...il.com, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [RFC PATCH] vsprintf: Add %p*D extension for 80211 SSIDs

于 2013年01月07日 12:49, Joe Perches 写道:
> On Sun, 2013-01-06 at 19:19 -0800, Joe Perches wrote:
>> Maybe these days this should be another vsprintf %p extension
>> like %pM when the DECLARE_MAC_BUF/print_mac uses were converted.
>>
>> (or maybe extend %ph for ssids with %*phs, length, array)
> 

  excuse me:
    I do not quite know how to reply the [RFC PATCH].
    it would be better if you can tell me how to do for [RFC PATCH], thanks.

    :-)


  at least for me:

    although it is good idea to add common, widely used features in public tools function.

    after searching the relative source code:
      it seems print ssid is not quite widely used (although it is a common feature).
        it is used by drivers/net/wireless/libertas
        it is used by drivers/net/wireless/ipw2x00
        no additional using in current kernel source code wide.
      if another modules want to print ssid,
        they can still call print_ssid now (EXPORT_SYMBOL in net/wireless).

    so at least now, it is not necessary to add this feature to public tools function.

  Regards

gchen.

> Maybe like this:
> 
>  lib/vsprintf.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 55 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index fab33a9..98916a0 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -26,6 +26,7 @@
>  #include <linux/math64.h>
>  #include <linux/uaccess.h>
>  #include <linux/ioport.h>
> +#include <linux/ieee80211.h>
>  #include <net/addrconf.h>
>  
>  #include <asm/page.h>		/* for PAGE_SIZE */
> @@ -660,10 +661,59 @@ char *resource_string(char *buf, char *end, struct resource *res,
>  }
>  
>  static noinline_for_stack
> +char *ssid_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
> +		  const char *fmt)
> +{
> +	int i, len = 1;		/* if we pass %*p, field width remains
> +				   negative value, fallback to the default */
> +
> +	if (spec.field_width == 0)
> +		/* nothing to print */
> +		return buf;
> +
> +	if (ZERO_OR_NULL_PTR(addr))
> +		/* NULL pointer */
> +		return string(buf, end, NULL, spec);
> +
> +	if (spec.field_width > 0)
> +		len = min_t(int, spec.field_width, IEEE80211_MAX_SSID_LEN);
> +
> +	for (i = 0; i < len && buf < end; i++) {
> +		if (isprint(addr[i])) {
> +			*buf++ = addr[i];
> +			continue;
> +		}
> +		*buf++ = '\\';
> +		if (buf >= end)
> +			continue;
> +		if (addr[i] == '\0')
> +			*buf++ = '0';
> +		else if (addr[i] == '\n')
> +			*buf++ = 'n';
> +		else if (addr[i] == '\r')
> +			*buf++ = 'r';
> +		else if (addr[i] == '\t')
> +			*buf++ = 't';
> +		else if (addr[i] == '\\')
> +			*buf++ = '\\';
> +		else {
> +			if (buf < end)
> +				*buf++ = ((addr[i] >> 6) & 7) + '0';
> +			if (buf < end)
> +				*buf++ = ((addr[i] >> 3) & 7) + '0';
> +			if (buf < end)
> +				*buf++ = ((addr[i] >> 0) & 7) + '0';
> +		}
> +	}
> +
> +	return buf;
> +}
> +
> +static noinline_for_stack
>  char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
>  		 const char *fmt)
>  {
> -	int i, len = 1;		/* if we pass '%ph[CDN]', field witdh remains
> +	int i, len = 1;		/* if we pass '%ph[CDN]', field width remains
>  				   negative value, fallback to the default */
>  	char separator;
>  
> @@ -695,7 +745,6 @@ char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
>  
>  	for (i = 0; i < len && buf < end - 1; i++) {
>  		buf = hex_byte_pack(buf, addr[i]);
> -
>  		if (buf < end && separator && i != len - 1)
>  			*buf++ = separator;
>  	}
> @@ -1016,6 +1065,8 @@ int kptr_restrict __read_mostly;
>   *             [0][1][2][3]-[4][5]-[6][7]-[8][9]-[10][11][12][13][14][15]
>   *           little endian output byte order is:
>   *             [3][2][1][0]-[5][4]-[7][6]-[8][9]-[10][11][12][13][14][15]
> + * - 'D' For a 80211 SSID, it prints the SSID escaping any non-printable
> +         characters with a leading \ and octal or [0nrt\]
>   * - 'V' For a struct va_format which contains a format string * and va_list *,
>   *       call vsnprintf(->format, *->va_list).
>   *       Implements a "recursive vsnprintf".
> @@ -1088,6 +1139,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
>  		break;
>  	case 'U':
>  		return uuid_string(buf, end, ptr, spec, fmt);
> +	case 'D':
> +		return ssid_string(buf, end, ptr, spec, fmt);
>  	case 'V':
>  		{
>  			va_list va;
> 
> 
> 
> 


-- 
Chen Gang

Asianux Corporation
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