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Date: Fri, 18 Dec 2015 07:26:24 -0700 (Mountain Standard Time)
From: Marc Aurele La France <tsi@tuyoix.net>
To: Peter Hurley <peter@hurleysoftware.com>
cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>, linux-kernel@vger.kernel.org,
        Volth <openssh@volth.com>, Damien Miller <djm@mindrot.org>
Subject: Re: n_tty: Check the other end of pty pair before returning EAGAIN
 on a read()
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On Fri, 11 Dec 2015, Peter Hurley wrote:
> On 12/11/2015 05:37 AM, Marc Aurele La France wrote:

>> I am not asking to read data before it has been produced.  I am puzzled
>> that despite knowing that the data exists, I can now be lied to when I
>> try to retrieve it, when I wasn't before.  We are talking about what is
>> essentially a two-way pipe, not some network or serial connection with
>> transmission delays userland has long experience in dealing with.

>> These previously internal additional delays, that are now exposed to
>> userland, are simply an implementation detail that userland did not,
>> and should not, need to worry about.
>
> Your mental model is that pseudo-terminals are a synchronous pipe, which
> is not true.
>
> But this argument is pointless because the regression needs to be fixed
> regardless of the merits.

Fair enough.

Anything new on this?

Thanks.

Marc.