Date: Fri, 8 Sep 2023 12:59:36 +0200
To: cygwin@cygwin.com
Subject: Re: NFS mkfifo support in cygwin 3.5.0 Re: [ANNOUNCEMENT] cygwin
 3.4.9-1
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From: Corinna Vinschen via Cygwin <cygwin@cygwin.com>
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Cc: Corinna Vinschen <corinna-cygwin@cygwin.com>
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On Sep  8 06:48, Cedric Blancher via Cygwin wrote:
> On Thu, 7 Sept 2023 at 23:20, Martin Wege via Cygwin <cygwin@cygwin.com> wrote:
> >
> > On Wed, Sep 6, 2023 at 5:27 PM Corinna Vinschen via Cygwin-announce
> > via Cygwin <cygwin@cygwin.com> wrote:
> > >
> > > The following packages have been uploaded to the Cygwin distribution:
> > >
> > > * cygwin-3.4.9-1
> > > * cygwin-devel-3.4.9-1
> > > * cygwin-doc-3.4.9-1
> > >
> > > Bug Fixes
> > > ---------
> > >
> > > - Fix a bug introduced in cygwin 3.4.0 that switch_to_nat_pipe flag is
> > >   not cleared properly when non-cygwin app is terminated in the case
> > >   where pseudo console is not activated.
> > >
> > > - For the time being, disable creating special files using mknod/mkfifo
> > >   on NFS.
> > >   Addresses: https://cygwin.com/pipermail/cygwin/2023-August/254266.html
> >
> > While I am unhappy that you disabled this for Cygwin 3.4.9-1, we
> > noticed that you added mkfifo support for Cygwin 3.5.0 in
> > https://cygwin.com/git/?p=newlib-cygwin.git;a=commit;h=622fb0776ea333dd708ff312f08ec98311138fbe
> > 🙏😁 :-)
> >
> > Thanks
> >
> > We are testing 3.5.0-0.423.g7ced682549ae.x86_64 - which includes
> > 622fb0776ea333dd708ff312f08ec98311138fbe - right now, feedback will
> > come on Monday
> 
> That's amazing news.
> 
> But an old bug crept in:
> H is NFS file system
> $ uname -a
> CYGWIN_NT-10.0-19045 bastille0x44ef 3.5.0-0.423.g7ced682549ae.x86_64
> 2023-09-07 17:19 UTC x86_64 Cygwin
> $ mount
> C:/cygwin64/bin on /usr/bin type ntfs (binary,auto)
> C:/cygwin64/lib on /usr/lib type ntfs (binary,auto)
> C:/cygwin64 on / type ntfs (binary,auto)
> C: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)
> H: on /cygdrive/h type nfs (binary,posix=0,user,noumount,auto)
> M: on /cygdrive/m type nfs (binary,posix=0,user,noumount,auto)
> N: on /cygdrive/n type nfs (binary,posix=0,user,noumount,auto)
> O: on /cygdrive/o type nfs (binary,posix=0,user,noumount,auto)
> P: on /cygdrive/p type nfs (binary,posix=0,user,noumount,auto)
> $ cd /cygdrive/h/tmp/
> $ mkfifo f1.fifo ; echo $?
> 0
> $ mkfifo -m 0600 f2.fifo ; echo $?
> mkfifo: cannot set permissions of 'f2.fifo': No such file or directory
> 1
> 
> So chmod() for a FIFO inode on NFS fails. Tested with MSFT NFSv3 and
> new builds of the NFSv4.1 ms-nfs41-client filesystems.

Did you actually test this with 3.4.8?  It never worked on NFS.

Just to be clear, the above creates a Cygwin FIFO.  The situation
is different with native FIFOs, created on the host.  With those,
chmod worked before because native FIFOs were handled like normal files,
except in stat(2).  Now that they are handled as FIFOs, the mechanism
to change the file mode doesn't work anymore, because it depends on
FIFOs being WIndows shortcuts.

I will look into that at one point, but it's not a regression.


Corinna

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