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Date:	Wed, 9 Aug 2023 11:56:43 +0200
To:	Martin Wege <martin DOT l DOT wege AT gmail DOT com>
Subject:	Re: mkfifo: cannot set permissions of 'x.fifo': Not a directory
Message-ID:	<ZNNi2//PUy0QPNa9@calimero.vinschen.de>
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From:	Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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Cc:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>, cygwin AT cygwin DOT com
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On Aug  9 11:12, Martin Wege via Cygwin wrote:
> On Wed, Aug 9, 2023 at 10:01 AM Corinna Vinschen
> <corinna-cygwin AT cygwin DOT com> wrote:
> >
> > On Aug  8 21:38, Martin Wege via Cygwin wrote:
> > > On Tue, Aug 8, 2023 at 10:20 AM Corinna Vinschen
> > > <corinna-cygwin AT cygwin DOT com> wrote:
> > > >
> > > > On Aug  7 23:14, Martin Wege via Cygwin wrote:
> > > > > Secondly, how are fifos, other device nodes and mknod implemented? You
> > > > > encode them as softlinks on ntfs?
> > > >
> > > > Not only on NTFS.  FIFOs on the disk are always created as symlinks
> > > > with a special target string, recognized by Cygwin.  No differece on
> > > > NFS.  Microsoft NFSv3 has no way to specify creating a "real" FIFO
> > > > on the remote filesystem.  It wouldn't make sense anyway, because
> > > > there's no way to share the FIFO across systems.
> > >
> > > So no Windows ioctl to do a mknod?
> >
> > Windows does not have provisions to store FIFOs on disk.  The closest
> > you get in Windows are Windows named pipes, and those are stored
> > non-permanently in a special, temporary filesystem inside the native NT
> > namespace.  Try this in Cygwin:
> >
> >   $ cd /proc/sys/Device/NamedPipe/    <-- trailing slash!
> >   $ ls -l
> >
> > FIFOs in the normal Windows filesystem are a Cygwin fake.
> 
> Maybe make pipes in Cygwin symlinks to /proc/sys/Device/NamedPipe/?

Why?  Windows Named Pipes don't act like UNIX FIFOs.

> > > What does a Linux/FreeBSD FIFO file look like, if you export that
> > > filesystem via NFSv3, and mount it via the native Windows NFSv3
> > > driver, and do a ls -l in Cygwin?
> >
> > It looks like a FIFO because MSFT NFSv3 exports the stat(2) info
> > verbatim:
> >
> > linux$ mkfifo blubb
> >
> > cygwin$ ls -l blubb
> > prw-r--r-- 1 corinna vinschen 0 Aug  8 10:22 blubb
> 
> Will cygwin treat this as a FIFO?

No.  Cygwin FIFOs != Unix FIFOs.

> Can cygwin set the 'p' flag via a magic ioctl?

No.  I don't understand your insistence to use FIFOs on NFS.  There is
no value in that, because you can't share them between systems anyway.

https://www.unix.com/unix-for-advanced-and-expert-users/10861-fifo-over-nfs.html
https://stackoverflow.com/questions/1038788/cant-write-to-fifo-file-mouted-via-nfs


Corinna

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