linux-kernel - Re: No NONBLOCK flag for dup3() or epoll

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Message-ID: <cfd18e0f0808291344g6c96a626x952a0016d3178053@mail.gmail.com>
Date:	Fri, 29 Aug 2008 22:44:08 +0200
From:	"Michael Kerrisk" <mtk.manpages@...glemail.com>
To:	"Ulrich Drepper" <drepper@...hat.com>
Cc:	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Al Viro" <viro@...iv.linux.org.uk>,
	lkml <linux-kernel@...r.kernel.org>,
	"Davide Libenzi" <davidel@...ilserver.org>
Subject: Re: No NONBLOCK flag for dup3() or epoll_create1()?

Ping!

On Wed, Aug 20, 2008 at 6:49 PM, Michael Kerrisk
<mtk.manpages@...glemail.com> wrote:
> Ulrich
>
> I've been doing some testing (2.6.27-rc3) of your new
> file-descriptor-creating syscalls that accept flags.  According to
>
> http://udrepper.livejournal.com/20407.html
>
> all of the system calls should accept a *_NONBLOCK flag.  All of them do,
> except for two:
> dup3(olfd, newfd, flags)
> and
> epoll_create1(flags).
>
> For epoll_create1() this certainly appears to be an oversight, since I can't
> think of a reason not to support *_NONBLOCK.
>
> For dup3() it is perhaps also an oversight.  However, it's not really clear
> to me whether supporting O_NONBLOCK makes sense, since that would change the
> file status flags of the open file description that is (also) referred to by
> oldfd.  (Furthermore, given a open file description for which O_NONBLOCK is
> already enabled, it is not possible to make a dup3() call that disables
> O_NONBLOCK, which is an odd asymmetry in the API.)  What are your thoughts
> on
> this?
>
> Cheers,
>
> Michael
>
>



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