X-Recipient: archive-cygwin AT delorie DOT com
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=1e100.net; s=20161025;
 h=x-gm-message-state:subject:to:cc:references:from:message-id:date
 :user-agent:mime-version:in-reply-to:content-language;
 bh=bH+AOompwHM0Lm65nxUrkJR3iRFKsclwlTddRJbEtVc=;
 b=naXcysSlDsKDVuYRHLrzloWIqkd5iQZs4W4RiRF01IoyWwysNuTQSepusSOoHTsQ4F
 CrDWTTNDMfN2BC73iZ1GRn3j3vtehb0aOife1hNW8HMSoNfktjakSPCrQjRTsH4wcdKQ
 NMuZ9C/c+OfyftVttEV1p7LjmtIIStl5LGuAnWYk32pxUd75K/oXPR68pOUc7AVctYFR
 T70FZpXMdPsoA4moYis2SrBRtwGY+4kinsAPf5P7JV9Tg1/QWOweIZDY0tqd0zwUmanJ
 LjZT7KKUD7mthuL+JrWHfFdyQz7sFQw8r+AqVSqDmUWOXHeOj9VDiSzrFdlGpHxTxOZq
 Y2fg==
X-Gm-Message-State: ANhLgQ0HG9+FPJ7/ypyiXnJ3x0761ZgtDjagRql2EGTRN/ppduIqQMqA
 HiVjOy74GSowYfuY4kc8dPU8YsRV6P0=
X-Google-Smtp-Source: ADFU+vuN/QdnbDYB1CR2nBaugAwGQhQdogEOqy250tvoVMBcFzI16/bme+4Ptsh+Ty7diEj9Ly5ToA==
X-Received: by 2002:ac2:4316:: with SMTP id l22mr4985607lfh.150.1584010866366; 
 Thu, 12 Mar 2020 04:01:06 -0700 (PDT)
Subject: Re: Setting termios VMIN > 0 and VTIME > 0 on non blocking file
To: Thomas Dickey <dickey AT his DOT com>
References: <mailman DOT 1473 DOT 1583981776 DOT 15804 DOT cygwin AT cygwin DOT com>
 <791909910 DOT 16332184 DOT 1584000356533 DOT JavaMail DOT zimbra AT his DOT com>
Message-ID: <a5818b72-23f5-d9d0-10a7-4ca2f47b35e3@gmail.com>
Date: Thu, 12 Mar 2020 12:01:01 +0100
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.5.0
MIME-Version: 1.0
In-Reply-To: <791909910.16332184.1584000356533.JavaMail.zimbra@his.com>
Content-Language: en-US
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, HTML_MESSAGE,
 RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,
 SPF_PASS autolearn=ham autolearn_force=no version=3.4.2
X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on
 server2.sourceware.org
X-Content-Filtered-By: Mailman/MimeDel 2.1.29
X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Cygwin mailing list <cygwin.cygwin.com>
List-Unsubscribe: <http://cygwin.com/mailman/options/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=unsubscribe>
List-Archive: <http://cygwin.com/pipermail/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe: <http://cygwin.com/mailman/listinfo/cygwin>,
 <mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From: =?utf-8?q?=C3=85ke_Rehnman_via_Cygwin?= <cygwin AT cygwin DOT com>
Reply-To: =?UTF-8?Q?=c3=85ke_Rehnman?= <ake DOT rehnman AT gmail DOT com>
Cc: cygwin <cygwin AT cygwin DOT com>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
Errors-To: cygwin-bounces AT cygwin DOT com
Sender: "Cygwin" <cygwin-bounces AT cygwin DOT com>
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from base64 to 8bit by delorie.com id 02CB1YlJ007790


On 2020-03-12 09:05, Thomas Dickey wrote:
> If not "correct", it's certainly inconsistent with all other systems.
> I noticed it recently:
>
> https://invisible-island.net/ncurses/tack/CHANGES.html#t20200220
>
> https://github.com/cygwinports/tack/issues/1
>
> It's either recently-broken, or just coincidence :-)


Beer fine for you Thomas for copying email-addresses in the reply :-)

Looking at Linux tty line discipline reveals the VMIN and VTIME are 
ignored if O_NONBLOCK flag is set.

         if (!input_available_p(tty, 0)) {
             up_read(&tty->termios_rwsem);
             tty_buffer_flush_work(tty->port);
             down_read(&tty->termios_rwsem);
             if (!input_available_p(tty, 0)) {
                 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
                     retval = -EIO;
                     break;
                 }
                 if (tty_hung_up_p(file))
                     break;
                 /*
                  * Abort readers for ttys which never actually
                  * get hung up.  See __tty_hangup().
                  */
                 if (test_bit(TTY_HUPPING, &tty->flags))
                     break;
                 if (!timeout)
                     break; *<= EXIT HERE if VTIME == 0*
                 if (file->f_flags & O_NONBLOCK) {
                     retval = -EAGAIN; *<==== EXIT HERE*
                     break;
                 }
                 if (signal_pending(current)) {
                     retval = -ERESTARTSYS;
                     break;
                 }
                 up_read(&tty->termios_rwsem);

                 timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, *<=== 
BLOCKING HERE!*
                         timeout);

                 down_read(&tty->termios_rwsem);
                 continue;
             }
         }

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple