linux-kernel - Re: dup2() vs dup3() inconsistency when

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Date:	Fri, 10 Oct 2008 14:15:23 +0200
From:	"Michael Kerrisk" <mtk.manpages@...glemail.com>
To:	"Bernd Petrovitsch" <bernd@...mix.at>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	"Ulrich Drepper" <drepper@...hat.com>,
	"Al Viro" <viro@...iv.linux.org.uk>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: dup2() vs dup3() inconsistency when

On Fri, Oct 10, 2008 at 2:09 PM, Bernd Petrovitsch <bernd@...mix.at> wrote:
> On Fri, 2008-10-10 at 07:04 +0200, Michael Kerrisk wrote:
> [....]
>> Well, as long as we are fixing the dup3() interface in the way that Al
>> and Ulrich have suggested, what about another fix:
>>
>> give an error if newfd is already open, thus forcing the user to do an
>> explicit close
>>
>> ?
>>
>> This silent close in dup2() is an implementation blemish.  Why not eliminate it?
>
> Apart from the usual "do not break almost all existing apps" killer
> reason: The alternative is that people will simply add a "close(newfd)"
> everytime before "dup2(oldfd,newfd)" since close() is harmless on a
> non-open fd.

Bernd,

I think you've missed the point.  The idea is not to change to dup2(),
but to eliminate the blemish in its design in the new dup3() (since we
have alrady eliminated one other blemish).

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git
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