X-Recipient: archive-cygwin AT delorie DOT com X-Spam-Check-By: sourceware.org Date: Mon, 22 Dec 2008 12:28:55 -0500 From: Christopher Faylor To: cygwin AT cygwin DOT com Subject: Re: Named pipes (blocking problem) Message-ID: <20081222172855.GB27364@ednor.casa.cgf.cx> Reply-To: cygwin AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com References: <005b01c96455$6c6bed60$4001a8c0 AT mycomputer> <2ca21dcc0812220903k38b8923v892f508b2ec55620 AT mail DOT gmail DOT com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2ca21dcc0812220903k38b8923v892f508b2ec55620@mail.gmail.com> User-Agent: Mutt/1.5.16 (2007-06-09) Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com Note-from-DJ: This may be spam On Mon, Dec 22, 2008 at 05:03:02PM +0000, Dave Korn wrote: >John Emmas wrote: >> I'm trying to build a program that implements inter-process communication >> using named pipes. Because the code needs to also work under Windows >> (MSVC++) it uses CreateNamedPipe(...) to create the pipes (described here):- >> >> http://msdn.microsoft.com/en-us/library/aa365150(VS.85).aspx >> >> If I understand the description, it seems that the created pipe can either >> be blocking or nonblocking depending on whether the flag >> FILE_FLAG_OVERLAPPED is specified at creation time. > > Nope. Overlapped and blocking are slightly different concepts; >overlapped basically means "enabled for asynchronous I/O". What >you're looking for is PIPE_WAIT/_NOWAIT, further down the same page. That's not exactly true. You can use FILE_FLAG_OVERLAPPED to simulate blocking or non-blocking behavior. If the OP is creating a pipe using CreateNamedPipe and then trying to somehow read it using Cygwin's I/O library then I wouldn't be surprised to see strange behavior. Otherwise, Cygwin does not impose any strange limitations on CreateNamedPipe. Note that if this really is just a pure Windows program you probably should be using MinGW. cgf -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/