linux-kernel - Re: [PATCH] Fix strim() semantics for strings that have only blanks

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Message-ID: <CAGje9yQOmBe45DC_k67AL4V24Pkr_+6MRFK4Gfj9uYNEGVOpkg@mail.gmail.com>
Date:	Mon, 17 Oct 2011 09:24:57 -0200
From:	André Goddard Rosa <andre.goddard@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Cc:	schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix strim() semantics for strings that have only blanks

Hello Michael,

On Thu, Oct 13, 2011 at 8:54 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Wed, 12 Oct 2011 10:31:57 +0200
> Michael Holzheu <holzheu@...ux.vnet.ibm.com> wrote:
>
>> Hello Andre,
>>
>> With git commit 84c95c9acf088c99d8793d78036b67faa5d0b851 a patch from
>> you went upstream where you wanted to improve the performance of the
>> strim() function.
>>
>> Unfortunately this changed the semantics of strim() and broke my code. Before
>> the patch it was possible to use strim() without using the return value for
>> removing trailing spaces from strings that had either only blanks or only
>> trailing blanks.
>>
>> Now this does not work any longer for strings that *only* have blanks.
>>
>> Before patch: "   " -> ""    (empty string)
>> After patch:  "   " -> "   " (no change)
>>
>> I think we should remove your patch to restore the old behavior.
>>
>> >From the description (lib/string.c):
>>
>>  * Note that the first trailing whitespace is replaced with a %NUL-terminator
>>
>> => The first trailing whitespace of a string that only has whitespace
>>    characters is the first whitespace
>
> Yes, that change makes sense.

breaking your code was not good at all. Is it maintained off tree?
I believe It happened because you use strim() without using its return.
In any case, I'm OK on reverting it to fix your problem.

Thanks,
André
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