linux-kernel - Re: [PATCH v7 1/3] mm: add kstrdup

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Message-Id: <20140205150101.f6fbe53db7d30a09854a5c5c@linux-foundation.org>
Date:	Wed, 5 Feb 2014 15:01:01 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Sebastian Capella <sebastian.capella@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-pm@...r.kernel.org, linaro-kernel@...ts.linaro.org,
	patches@...aro.org, "Michel Lespinasse" <walken@...gle.com>,
	"Shaohua Li" <shli@...nel.org>,
	"Jerome Marchand" <jmarchan@...hat.com>,
	"Mikulas Patocka" <mpatocka@...hat.com>,
	"Joonsoo Kim" <iamjoonsoo.kim@....com>,
	"Joe Perches" <joe@...ches.com>,
	"David Rientjes" <rientjes@...gle.com>,
	"Alexey Dobriyan" <adobriyan@...il.com>,
	"Pavel Machek" <pavel@....cz>
Subject: Re: [PATCH v7 1/3] mm: add kstrdup_trimnl function

On Wed, 05 Feb 2014 14:55:52 -0800 Sebastian Capella <sebastian.capella@...aro.org> wrote:

> Quoting Andrew Morton (2014-02-05 13:50:52)
> > On Tue,  4 Feb 2014 12:43:49 -0800 Sebastian Capella <sebastian.capella@...aro.org> wrote:
> > 
> > > kstrdup_trimnl creates a duplicate of the passed in
> > > null-terminated string.  If a trailing newline is found, it
> > > is removed before duplicating.  This is useful for strings
> > > coming from sysfs that often include trailing whitespace due to
> > > user input.
> > 
> > hm, why?  I doubt if any caller of this wants to retain leading and/or
> > trailing spaces and/or tabs.
> 
> Hi Andrew,
> 
> I agree the common case doesn't usually need leading or trailing whitespace.
> 
> Pavel and others pointed out that a valid filename could contain
> newlines/whitespace at any position.

The number of cases in which we provide the kernel with a filename via
sysfs will be very very small, or zero.

If we can go through existing code and find at least a few sites which
can usefully employ kstrdup_trimnl() then fine, we have evidence.  But
I doubt if we can do that?
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