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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	"David S. Miller" <davem@davemloft.net>,
	linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH v2 3/3] lib/string_helpers.c: Change semantics of string_escape_mem
Date: Mon, 02 Feb 2015 12:56:37 +0200	[thread overview]
Message-ID: <1422874597.31903.358.camel@linux.intel.com> (raw)
In-Reply-To: <87pp9vhm8l.fsf@rasmusvillemoes.dk>

On Sat, 2015-01-31 at 00:39 +0100, Rasmus Villemoes wrote:
> On Fri, Jan 30 2015, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> >> >>   * Return:
> >> >> - * The amount of the characters processed to the destination buffer, or
> >> >> - * %-ENOMEM if the size of buffer is not enough to put an escaped character is
> >> >> - * returned.
> >> >> - *
> >> >> - * Even in the case of error @dst pointer will be updated to point to the byte
> >> >> - * after the last processed character.
> >> >> + * The total size of the escaped output that would be generated for
> >> >> + * the given input and flags. To check whether the output was
> >> >> + * truncated, compare the return value to osz. There is room left in
> >> >> + * dst for a '\0' terminator if and only if ret < osz.
> >> >>   */
> >> >> -int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz,
> >> >> -		      unsigned int flags, const char *esc)
> >> >> +size_t string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
> >> >> +			 unsigned int flags, const char *esc)
> >> >
> >> > I prefer to leave the prototype the same. int for return is okay. dst
> >> > should be updated accordingly.
> >> 
> >> Please explain exactly what you think the return value should be, and
> >> what *dst should be set to.
> >
> > Return value like you proposed, *dst is incremented by it.
> 
> The more I think about it, the less I like having dst being char**.
> 
> (1) It is unlike most other functions taking buffer+size arguments.
> (2) It is inconvenient. Callers doing
> 
>   char escaped[SOME_SIZE];
> 
> or
> 
>   char *escaped = kmalloc(likely_big_enough);
> 
> can't just pass &escaped; they would need to use an extra dummy variable.
> 
> (3) With the return value telling the size of the would-be generated
> output, it is redundant.
> 
> In fact, I dislike it so much that I'm not going to sign off on a patch
> where dst is still char**.

Fair enough, though there usual case when temporary variable is already
present (at least current users).

Let's proceed with char *dst.

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


  reply	other threads:[~2015-02-02 10:56 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
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 [this message]
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

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