From: Petr Baudis <pasky@ucw.cz>
Date: Sat, 06 Apr 2013 10:34:26 GMT
Subject: Re: [PATCH v2 1/2] perl: redirect stderr to /dev/null instead of closing
Message-ID: <20130406103426.GE6137@machine.or.cz>
In-Reply-To: <878v4wrsj7.fsf@linux-k42r.v.cablecom.net>

On Sat, Apr 06, 2013 at 10:07:40AM +0200, Thomas Rast wrote:
> The manpage for dup2 does, however, say
> 
>    If newfd was open, any errors  that  would  have  been  reported  at
>    close(2) time are lost.  A careful programmer will not use dup2() or
>    dup3() without closing newfd first.
> 
> which is probably what you were referring to.

Yes, that's probably one reason why I had this stuck in my mind (though,
how often does anyone bother to detect errors on close()...? ;-).

Funnily enough, POSIX.2008 specifies that if closing newfd would fail,
dup2() reports EIO and newfd is not closed, eliminating this problem.

The manpage does not cover this; well, that's fair enough as Linux just
doesn't care and never does that if I didn't miss anything in the code.

-- 
			Petr "Pasky who might even send
				a patch, but the matter is
				oh so obscure" Baudis