linux-kernel - Re: [PATCH 2/3] string: provide strscpy() and strscpy

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Message-ID: <20150507090034.GV16501@mwanda>
Date:	Thu, 7 May 2015 12:00:34 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Chris Metcalf <cmetcalf@...hip.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Fabian Frederick <fabf@...net.be>,
	Randy Dunlap <rdunlap@...radead.org>,
	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>,
	Greg KH <gregkh@...uxfoundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"David S. Miller" <davem@...emloft.net>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sam Ravnborg <sam@...nborg.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	"Theodore Ts'o" <tytso@....edu>,
	Grant Likely <grant.likely@...aro.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux-Arch <linux-arch@...r.kernel.org>
Subject: Re: [PATCH 2/3] string: provide strscpy() and strscpy_truncate()

On Wed, May 06, 2015 at 06:45:56PM +0200, Geert Uytterhoeven wrote:
> On Wed, May 6, 2015 at 5:59 PM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
> > We actually do have a __must_check tag so it's easy enough to force
> > people to check.  A different option is we could make it trigger a
> 
> People tend to ignore compiler warnings...

We're doing a lot better these days with zero day build testing.  There
is not even one ignored __must_check return in my allmodconfig.

> 
> > WARN_ONCE().
> >
> > #define strXcpy(dest, src, len) (({                             \
> >         ssize_t __ret = strscpy_truncate(dest, src, len);       \
> >         WARN_ONCE(__ret < 0, "strXcpy trancates\n");            \
> >         __ret; }))
> 
> Which will probably trigger only in extreme cases in the wild, not during
> development.

It's less subtle than just putting an empty string there so we're more
likely to get bug reports than with the original code.

regards,
dan carpenter
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