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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Konstantin Osipov <kostja.osipov@gmail.com>
Cc: tml <tarantool-patches@dev.tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH 1/5] popen: Introduce a backend engine
Date: Sat, 30 Nov 2019 13:47:34 +0300	[thread overview]
Message-ID: <20191130104734.GR19879@uranus> (raw)
In-Reply-To: <20191130100445.GA16163@atlas>

On Sat, Nov 30, 2019 at 01:04:45PM +0300, Konstantin Osipov wrote:
> 
> Could you provide a Lua example usage of popen() which would lead 
> to the situation you describe here?
> 
> Seems like in order for that to happen the Lua script has to
> provide both input and output streams to the called program, and
> in this case the script should not expect that there is any
> ordering in which the input is consumed and the output is
> produced.
> 
> In any case discussing this problem would be easier if there is an
> example.

An example is in one of my patch, here is it (result file)
---

--
-- Test for stdin/out stream
--
script="prompt=''; read -n 5 prompt; echo -n $prompt"
 | ---
 | ...
popen = fio.popen(script, "rw")
 | ---
 | ...
popen:write("input")
 | ---
 | - 5
 | ...
popen:read()
 | ---
 | - input
 | ...
popen:close()
 | ---
 | - true
 | - null
 | ...

The main thing is that as far as I remember "real" stdin/out/err are
the unix pty terminals, and they are in blocking mode. IOW if you
run

 $ sh -c "prompt=''; read -n 5 prompt; echo -n $prompt"

inside real shell the read will be blocked until you enter data
to stdin. And I think users of popen will expect the same behaviour.
Anyway, Kostya, I'll investigate python behaviour more on the weekend
to get in with more details.

  reply	other threads:[~2019-11-30 10:47 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-28 20:45 [Tarantool-patches] [PATCH 0/5] popen: Add ability to run external process Cyrill Gorcunov
2019-11-28 20:45 ` [Tarantool-patches] [PATCH 1/5] popen: Introduce a backend engine Cyrill Gorcunov
2019-11-29  5:52   ` Konstantin Osipov
2019-11-29  9:57     ` Cyrill Gorcunov
2019-11-29  5:59   ` Konstantin Osipov
2019-11-29  9:40     ` Cyrill Gorcunov
2019-11-29 11:19       ` Konstantin Osipov
2019-11-29 11:36         ` Cyrill Gorcunov
2019-11-29 14:50           ` Konstantin Osipov
2019-11-29 15:14             ` Cyrill Gorcunov
2019-11-29 15:17               ` Cyrill Gorcunov
2019-11-29 18:31               ` Konstantin Osipov
2019-11-29 19:17                 ` Cyrill Gorcunov
2019-11-29 22:36                   ` Cyrill Gorcunov
2019-11-30  4:21                     ` Konstantin Osipov
2019-11-30  7:48                       ` Cyrill Gorcunov
2019-11-30  4:14                   ` Konstantin Osipov
2019-11-30  7:36                     ` Cyrill Gorcunov
2019-11-30 10:04                       ` Konstantin Osipov
2019-11-30 10:47                         ` Cyrill Gorcunov [this message]
2019-11-30 10:54                           ` Cyrill Gorcunov
2019-11-30 12:16                             ` Cyrill Gorcunov
2019-11-30 20:30                             ` Konstantin Osipov
2019-11-30 20:36                               ` Cyrill Gorcunov
2019-12-13  2:50   ` Alexander Turenko
2019-11-28 20:45 ` [Tarantool-patches] [PATCH 2/5] lua/fio: Add lbox_fio_push_error as a separate helper Cyrill Gorcunov
2019-11-29  6:02   ` Konstantin Osipov
2019-11-29  9:47     ` Cyrill Gorcunov
2019-11-29 11:22       ` Konstantin Osipov
2019-11-29 11:42         ` Cyrill Gorcunov
2019-11-29 14:51           ` Konstantin Osipov
2019-11-28 20:45 ` [Tarantool-patches] [PATCH 3/5] popen/fio: Merge popen engine into fio internal module Cyrill Gorcunov
2019-11-28 20:45 ` [Tarantool-patches] [PATCH 4/5] popen/fio: Implement lua interface for a popen object Cyrill Gorcunov
2019-11-28 20:45 ` [Tarantool-patches] [PATCH 5/5] test: Add app/popen test Cyrill Gorcunov

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