linux-kernel - Re: [PATCH v2 04/10] lib/vsprintf: add %*pE[achnops] format specifier

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Date:	Tue, 08 Jul 2014 11:50:00 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Joe Perches <joe@...ches.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 v2 04/10] lib/vsprintf: add %*pE[achnops] format
 specifier

On Mon, 2014-07-07 at 09:25 -0700, Joe Perches wrote:
> [trivial notes]

Thanks! Fixed locally, though am waiting for few more days if any other
comment comes.

> 
> On Mon, 2014-07-07 at 18:21 +0300, Andy Shevchenko wrote:
> > This allows user to print a given buffer as esaped string. The rules applied
> 
> as an escaped
> 
> > accordingly to the mix of the flags provided by additional format letters.
> 
> rules are applied according to an optional mix of flags
> 
> > For example, if the given buffer:
> > 
> > 	1b 62 20 5c 43 07 22 90 0d 5d
> > 
> > The result strings could be:
> 
> would be
> 
> > 	%*pE            "\eb \C\a"\220\r]"
> 
> Maybe say something about ssid's here.

Mentioned in the printk-formats.txt part.

> or maybe add an %*pES just for the ssid type.

I gave a thought to it, and it seems to me we will increase complexity
of the code to get none beneficial. The SSID in most cases has a
variable-length, thus we will pass it anyway, what else could be differ
here? Default set of flags?

> 
> > diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
> []
> > @@ -70,6 +70,34 @@ DMA addresses types dma_addr_t:
> >  	For printing a dma_addr_t type which can vary based on build options,
> >  	regardless of the width of the CPU data path. Passed by reference.
> >  
> > +Raw buffer as an escaped string:
> > +
> > +	%*pE[achnops]
> > +
> > +	For printing raw buffer as an escaped string. For the following buffer
> > +
> > +		1b 62 20 5c 43 07 22 90 0d 5d
> > +
> > +	few examples show how the conversion could be done (the result string
> > +	without embraced quotes):
> 
> 'embraced' is a bit of an awkward word choice.  Maybe surrounding.
> 
> > +
> > +		%*pE		"\eb \C\a"\220\r]"
> 
> Oh, the initial commit log comments above are really for this block

Phrasing is a bit different, though I rephrased above sentence.

> 
> > +		%*pEhp		"\x1bb \C\x07"\x90\x0d]"
> > +		%*pEa		"\e\142\040\\\103\a\042\220\r\135"
> > +
> > +	The converion rules are defined by combination of the following flags
> 
> conversion
> 
> > +	(see string_escape_mem() kernel documentation for the details):
> > +		a - ESCAPE_ANY
> > +		c - ESCAPE_SPECIAL
> > +		h - ESCAPE_HEX
> > +		n - ESCAPE_NULL
> > +		o - ESCAPE_OCTAL
> > +		p - ESCAPE_NP
> > +		s - ESCAPE_SPACE
> > +	By default ESCAPE_ANY_NP is used.
> > +
> > +	If field width is ommited the 1 byte only will be escaped.
> 
> omitted
> 
> 


-- 
Andy Shevchenko <andriy.shevchenko@...el.com>
Intel Finland Oy

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