linux-kernel - Re: Does Linux select() violate POSIX?

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Message-ID: <BANLkTimAxbVWzahU8Ke_Rb8bgiVVrsihRA@mail.gmail.com>
Date:	Sun, 19 Jun 2011 15:21:27 -0700
From:	Nemo Publius <nemo@...f-evident.org>
To:	Bernd Petrovitsch <bernd@...rovitsch.priv.at>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Eric Dumazet <eric.dumazet@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Does Linux select() violate POSIX?

On Sun, Jun 19, 2011 at 7:41 AM, Bernd Petrovitsch
<bernd@...rovitsch.priv.at> wrote:
> On Sam, 2011-06-18 at 11:51 -0700, Nemo Publius wrote:
>
> Then you should reformulate your question because the answer is
> technically correct.

First of all, had you bothered to read the very next sentence in the
Email to which you felt the need to reply, you would find I did
precisely that:

    "Of course I am talking about select() followed by recv() without
any intervening user-space operations on the descriptor."

Second, you are wrong.  I basically asked, "Is select() followed by
recv() guaranteed not to block?"

Possible answers include:

"No; your computer might crash."

"No; your kernel image might be corrupt."

"No; space aliens might destroy the earth."

"No; some other process might access the descriptor in the meantime."

All of these are "technically" correct.  All of them are also
completely useless.  You -- and everyone else who read my question --
know _exactly_ what I was asking.

And I got my answer, which is yes, Linux select() violates POSIX, and
that decision is deliberate.

But again, thank you so much for your valuable contribution to the discussion.
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