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Date:	Mon, 22 Dec 2008 12:28:55 -0500
From:	Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: Named pipes (blocking problem)
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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

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