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Date:	Mon, 9 Dec 2024 14:17:58 +0100
To:	cygwin AT cygwin DOT com
Subject:	Re: cygpath and unc paths
Message-ID:	<Z1buBnm2WlNEG8t1@calimero.vinschen.de>
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	<053d21b3-ee11-4858-a60d-54cd154fd98c AT kircheis DOT it>
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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>
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On Dec  9 13:47, Federico Kircheis via Cygwin wrote:
> On 09/12/2024 12.46, Corinna Vinschen via Cygwin wrote:
> > On Dec  6 13:23, Federico Kircheis via Cygwin wrote:
> > > Hello,
> > > 
> > > was it considered to add a flag to cygpath to output a path in unc format?
> > 
> > No.  But it wouldn't be much work.
> 
> It would be very nice if it ever happens.
> 
> > > For example, the folder
> > > 
> > > C:\test.
> > > 
> > > cannot be accessed from many Windows applications (powershell and cmd
> > > included) because of the trailing dot, while cygwin has no issue creating,
> > > accessing and deleting such files/folders.
> > > 
> > > Using an unc path
> > > 
> > > \\?\C:\test.
> > > 
> > > solves the issue for some programs, but cygpath currently misses an option
> > > for creating such path.
> > 
> > As a workaround you can just prepend the long path prefix:
> > 
> >    echo -n '\\?\'; cygpath ...
> 
> Which is what I'm doing, plus special-casing
> 
> 1)
> root path, like C:\ , because for whatever reason \\?\C:\ is not valid, it
> has to be a subfolder (and trying to trick it with \\?\C:\\ does not work
> either).

In which scenario?  \\?\C:\ is just the same as \??\C:\ in NT speak, and
that's a perfectly valid directory path.

> 2)
> unmounted network drives (\\server\path)

Yeah, those have a different prefix:

  \\?\UNC\server\share

> I'm not sure how a --unc should handle those cases.
> For all things I have in mind, not appending \\?\ is preferred, but someone
> might expect a hard error.
> 
> Either way, it is another reason why it makes sense for cygpath to handle
> those cases, currently I have to parse it's output before prepending '\\?\'.

I'll take a look.

> > > Notice that creating a dos path leads to an error.
> > 
> > I don't understand. Creating which DOS path with which application?
> 
> I meant that it is not possible to create a DOS path to C:\test., thus using
> a dos path is not a viable workaround to unc:
> 
> ----
> > cd 'C:/test.'
> > cygpath -ws .
> cygpath: cannot create short name of .
> ----

Don't use -s, it's just for the old short name style of DOS paths.
Nobody should actually need this nowadays, and sometimes short paths
don't even exist.  It's a functionality inside the FS driver, afaik, and
it can be switched off in the system.

In your example, standard filenames work:

  $ cd /cygdrive/c
  $ mkdir test.
  $ cd test.
  $ cygpath -ws .
  cygpath: cannot create short name of C:\test.
  $ cygpath -wa .
  C:\test.


Corinna

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