Date: Fri, 10 Oct 2008 16:43:51 +0300
From: Heikki Orsila <shdl@zakalwe.fi>
To: Ulrich Drepper <drepper@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, mtk.manpages@gmail.com,
       Al Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: dup2() vs dup3() inconsistency when
Message-ID: <20081010134351.GL16289@zakalwe.fi>
References: <cfd18e0f0810090510i87f088fi9eeea829ae2b58c1@mail.gmail.com> <48EE3D84.6000003@zytor.com> <48EE6A2B.8030005@redhat.com>
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On Thu, Oct 09, 2008 at 01:31:39PM -0700, Ulrich Drepper wrote:
> H. Peter Anvin wrote:
> > The dup2() behavior comes from the logical consequence of dup2()'s
> > "close on reuse"; one would think it would be logical for dup3() to
> > behave the same way.
> 
> No.  We deliberately decided on this change.  Otherwise, what is the
> result of dup3(fd, fd, O_CLOEXEC)?  There is no reason to use
> dup2(fd,fd), so why the hell somebody wants to defend this is beyond me.

The reason is: application programmers expect it to behave that way. 
The interface is mostly targeted for typical application programmers, 
and consistency decreases bugs. In this respect, it would be a good 
idea for dup3() to have the same semantics. Doing that might not make 
practical sense, but it is secondary to obviousness.

-- 
Heikki Orsila
heikki.orsila@iki.fi
http://www.iki.fi/shd
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