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Date: Mon, 13 Nov 2017 01:35:46 +0000
From: Brooks Davis <brooks@freebsd.org>
To: Mariusz Zaborski <oshogbo@FreeBSD.org>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: Re: svn commit: r325741 - head/sbin/dhclient
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On Sun, Nov 12, 2017 at 08:54:23AM +0000, Mariusz Zaborski wrote:
> Author: oshogbo
> Date: Sun Nov 12 08:54:23 2017
> New Revision: 325741
> URL: https://svnweb.freebsd.org/changeset/base/325741
>=20
> Log:
>   dhclient(8) should not close stdio using daemon(3) function.
>  =20
>   dhclient(8) is chrooted so opening /dev/null always will fail.
>   In capability world this is also annoying because we getting error that
>   open(2) is not permitted in Capsicum. dhclient(8) is closing stdio by
>   precaching fd to /dev/null before chroot.
>   This is done few lines below daemon(3) function so let's not try to do =
that
>   in daemon(3) function.

This makes me wonder if there would be some sense in a syscall that
just creates a file descriptor morally equivalant to opening /dev/null.

A slightly crazy option would be to extend dup2 to treat some invalid
descriptor (-2?) as that.

-- Brooks

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