X-Recipient: archive-cygwin@delorie.com X-Original-To: cygwin@cygwin.com Delivered-To: cygwin@cygwin.com DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 951183858D28 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=lyx.org Authentication-Results: sourceware.org; spf=none smtp.mailfrom=lyx.org Message-ID: <1b28b650-b588-e34f-919e-e75f5a01196f@lyx.org> Date: Tue, 20 Sep 2022 00:05:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.1 To: cygwin@cygwin.com References: From: Enrico Forestieri Subject: Re: FIFO issues In-Reply-To: X-Spam-Status: No, score=0.5 required=5.0 tests=BAYES_00, HTML_MESSAGE, KAM_DMARC_STATUS, KAM_LAZY_DOMAIN_SECURITY, NICE_REPLY_A, RCVD_IN_BARRACUDACENTRAL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: cygwin-bounces+archive-cygwin=delorie.com@cygwin.com Sender: "Cygwin" Ken Brown wrote: > I did an internet search on this issue and found the following, which describes the > situation we're discussing: > https://stackoverflow.com/questions/14594508/fifo-pipe-is-always-readable-in-select > According to that post, select on Linux will wait for a writer the first time it's > called to check read readiness for a FIFO opened for reading with O_NONBLOCK set. > But if the writer then closes the FIFO, subsequent calls to select will always find > the FIFO read ready (and read will return 0). This behavior is not documented, as far as > I can tell, and in fact it contradicts the existing documentation (both POSIX and Linux). > So I don't think someone trying to write a portable program should rely on it. Please, note that this code was working on cygwin the way it works on linux until some time ago, maybe last year, I am not sure. I also found this stackoverflow discussion: https://stackoverflow.com/questions/28851639/select-with-non-blocking-reads I tried the code also on Solaris and NetBSD and it works exactly as on linux, so I think it is portable. -- Enrico -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple