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Date: Mon, 06 Jul 2009 07:12:27 -0600
From: Eric Blake <ebb9 AT byu DOT net>
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To: cygwin AT cygwin DOT com
Subject: Re: [1.7] fifo regression
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According to Eric Blake on 7/6/2009 7:03 AM:
> But on cygwin 1.7, when you attempt to create multiple writers to a single
> fifo, the second writer creates an fd just fine but then fails on any
> attempt to write to that fd:
> 
> $ mkfifo fifo
> $ (exec 5>fifo; sleep 25; echo one >&5)&
> [1] 4200
> $ (exec 5>fifo; sleep 15; echo two >&5)&
> [2] 204

It appears that part of the problem is that cygwin is violating POSIX - a
process that opens a fifo for writes must block until a corresponding
process opens the same fifo for reads, but cygwin is creating the fd
without blocking.  A pstree at this point shows that the sleep processes
have already been spawned...

> $ exec 5<fifo

...even though on Linux, the sleeps cannot spawn until after this point.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9 AT byu DOT net
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