All of lore.kernel.org
 help / color / mirror / Atom feed
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mathias Krause <minipli@googlemail.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] lib/string_helpers.c: Refactor string_escape_mem
Date: Thu, 29 Jan 2015 15:37:29 +0200	[thread overview]
Message-ID: <1422538649.31903.330.camel@linux.intel.com> (raw)
In-Reply-To: <87sietbulp.fsf@rasmusvillemoes.dk>

On Thu, 2015-01-29 at 14:10 +0100, Rasmus Villemoes wrote:
> On Thu, Jan 29 2015, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:


> >> -	*out++ = '\\';
> >> -	*out++ = to;
> >> +	if (out + 0 < end)
> >> +		out[0] = '\\';
> >> +	if (out + 1 < end)
> >> +		out[1] = to;
> >
> > Could we do this in the same way like for hex_string, i.e.
> >
> > if (out < end)
> >  *out = '\\';
> > ++out;
> >
> > …
> >
> > *dst = out;
> > return true;
> >
> > ?
> 
> We could, but I don't think either is more readable than the
> other. Hence I chose the one requiring 2n+1 lines instead of 3n+1
> lines. Had this been in vsprintf.c I would stick to the pattern you
> suggest.

I think the pattern with 3n lines is a bit more readable.

> >> +	ret = p - *dst;
> >>  	*dst = p;
> >> -
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >> -	return p - out;
> >
> > …and do not change the logic right now. Just substitute if (ret < 0) by
> > above if (p > end).
> >
> 
> I'm not sure I follow. How does this change the logic? We return -ENOMEM
> if and only if the entire output didn't fit, while still updating *dst
> to point to one past the last output character. If the output did fit,
> we return the size of the output.

I meant to do the arithmetics like it was in the original code.

> One thing that only occured to me now is that we may now leave a partial
> escape sequence at the end of the buffer. I can't see how this can
> reasonably be avoided

I don't know which way is better, but you may check how it was done in
the original code. First it was checking for enough space, and only
after filling the destination buffer.

fs/proc/array.c, for example, originally might leave the back slash at
the end.

>  while still doing a meaningful refactorization
> preparing it for the next patch.
> 
> Rasmus


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


  reply	other threads:[~2015-01-29 13:37 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-28 13:25 [PATCH 0/2] Two printf fixes Rasmus Villemoes
2015-01-28 13:25 ` [PATCH 1/2] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-01-28 14:53   ` Andy Shevchenko
2015-01-28 15:49     ` Rasmus Villemoes
2015-01-28 16:43       ` Andy Shevchenko
2015-01-28 13:25 ` [PATCH 2/2] string_helpers: Change semantics of string_escape_mem Rasmus Villemoes
2015-01-28 15:05   ` Andy Shevchenko
2015-01-29 10:03 ` [PATCH v2 0/3] Two printf fixes Rasmus Villemoes
2015-01-29 10:03   ` [PATCH v2 1/3] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-01-29 10:43     ` Andy Shevchenko
2015-01-29 10:03   ` [PATCH v2 2/3] lib/string_helpers.c: Refactor string_escape_mem Rasmus Villemoes
2015-01-29 12:12     ` Andy Shevchenko
2015-01-29 13:10       ` Rasmus Villemoes
2015-01-29 13:37         ` Andy Shevchenko [this message]
2015-01-29 19:33           ` Jeff Epler
2015-01-30 10:14             ` Andy Shevchenko
2015-01-29 10:03   ` [PATCH v2 3/3] lib/string_helpers.c: Change semantics of string_escape_mem Rasmus Villemoes
2015-01-29 13:29     ` Andy Shevchenko
2015-01-29 14:29       ` Rasmus Villemoes
2015-01-30 10:27         ` Andy Shevchenko
2015-01-30 23:39           ` Rasmus Villemoes
2015-01-30 23:39             ` Rasmus Villemoes
2015-02-02 10:56             ` Andy Shevchenko
2015-02-09 23:44   ` [PATCH v3 0/3] Two printf fixes Rasmus Villemoes
2015-02-09 23:44     ` Rasmus Villemoes
2015-02-09 23:44     ` [PATCH v3 1/3] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-02-09 23:44     ` [PATCH v3 2/3] lib/string_helpers.c: Refactor string_escape_mem Rasmus Villemoes
2015-02-10 12:16       ` Andy Shevchenko
2015-02-09 23:44     ` [PATCH v3 3/3] lib/string_helpers.c: Change semantics of string_escape_mem Rasmus Villemoes
2015-02-09 23:44       ` Rasmus Villemoes
2015-02-10 12:32       ` Andy Shevchenko
2015-02-10 12:32         ` Andy Shevchenko
2015-02-10 13:02         ` Rasmus Villemoes
2015-02-10 14:22           ` Andy Shevchenko
2015-02-10 14:22             ` Andy Shevchenko
2015-02-21  1:35             ` Rasmus Villemoes
2015-02-23 12:50               ` Andy Shevchenko
2015-02-23 12:50                 ` Andy Shevchenko
2015-02-23 22:55                 ` Rasmus Villemoes
2015-02-23 22:55                   ` Rasmus Villemoes
2015-03-02 12:37                   ` Andy Shevchenko
2015-03-02 12:37                     ` Andy Shevchenko
2015-03-02 23:03                     ` Rasmus Villemoes
2015-03-03 10:26                       ` Andy Shevchenko
2015-03-03 10:26                         ` Andy Shevchenko
2015-03-03 23:20     ` [PATCH v4 0/3] Two printf fixes Rasmus Villemoes
2015-03-03 23:20       ` [PATCH v4 1/3] lib/vsprintf.c: Fix potential NULL deref in hex_string Rasmus Villemoes
2015-03-03 23:20       ` [PATCH v4 2/3] lib/string_helpers.c: Refactor string_escape_mem Rasmus Villemoes
2015-03-04 10:51         ` Andy Shevchenko
2015-03-03 23:20       ` [PATCH v4 3/3] lib/string_helpers.c: Change semantics of string_escape_mem Rasmus Villemoes
2015-03-04 11:49         ` Andy Shevchenko
2015-03-04 11:49           ` Andy Shevchenko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1422538649.31903.330.camel@linux.intel.com \
    --to=andriy.shevchenko@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@rasmusvillemoes.dk \
    --cc=minipli@googlemail.com \
    --subject='Re: [PATCH v2 2/3] lib/string_helpers.c: Refactor string_escape_mem' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.