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From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: [musl] Incompatible behaviour of res_query(3) w.r.t. NXDOMAIN
Date: Mon, 24 Aug 2020 18:09:23 -0400	[thread overview]
Message-ID: <20200824220922.GN3265@brightrain.aerifal.cx> (raw)
In-Reply-To: <0422ED16-0AA3-402E-8103-940EC2545A3B@rb67.eu>

On Mon, Aug 24, 2020 at 11:51:52PM +0200, Daniel Neri wrote:
> On 24 Aug 2020, at 23:32, Rich Felker <dalias@libc.org> wrote:
> > 
> > Does such a distinction exist? I thought res_query was just equivalent
> > to res_mkquery+res_send and that calling res_send directly would get
> > you the same errors.
> 
> I thought so too, but I’ve been reading the musl implementation. ;-)
> 
> After looking more at the other implementations, I think Florian is
> correct though: it’s more like res_mkquery+res_send+setting h_errno
> and the return value based on the RCODE of the response.

If this is indeed the case and the right behavior can be obtained
reliably by ignoring res_query and using res_mkquery+res_send, I have
no fundamental objection to changing this. However we should have a
plan for moving h_errno to be thread-local and figuring out what
breakage if any there could be for apps built with it global.

Thankfully, it looks like we're already using (*__h_errno_location())
even though it was not thread-local, so existing apps built against
current musl headers should be immediately compatible with changing it
to be thread-local.

Rich

  reply	other threads:[~2020-08-24 22:09 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-23 21:31 Daniel Neri
2020-08-24 16:16 ` Rich Felker
2020-08-24 16:43   ` Rich Felker
2020-08-24 20:39     ` Daniel Neri
2020-08-24 21:36       ` Rich Felker
2020-08-24 21:04     ` Florian Weimer
2020-08-24 21:32       ` Rich Felker
2020-08-24 21:51         ` Daniel Neri
2020-08-24 22:09           ` Rich Felker [this message]
2020-08-25  3:26             ` Rich Felker
2020-08-25 13:56               ` Daniel Neri
2020-08-24 22:04         ` Florian Weimer
2020-08-24 22:13           ` Rich Felker

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