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Date: Wed, 3 Aug 2005 22:08:18 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin and NTFS Junction Points
Message-ID: <20050803200818.GI14783@calimero.vinschen.de>
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On Aug  3 11:57, Brian Dessent wrote:
> Richard Campbell wrote:
> 
> > > To some degree, Junction Points are more like directory HARD links,
> > > rather than symlinks.
> > 
> > What degree is this?
> > 
> > Everything I can see seems to say junction points function as symlinks
> > for directories, with retargeting, dangling, and fixing options.
> > 
> > I admit the documentation I have been looking at is sketchy - do you
> > have some better info?
> 
> You can't use a junction point to make a relative link, as you can with
> symbolic links.  That makes them significantly less useful.

That makes them next to useless from a POSIX point of view.  Actually,
even though junction points allow to create links to directories on the
same file system (but not to files *shaking head*), the important
functionality is to allow to mount file systems into the hirarchy of
another file system.  To me, junction points are more like mount points,
not symlinks.  Since mount points are transparent and don't act like
symlinks to cp/mv/rm and friends, I won't opt for treating junctions as
symlinks in the Cygwin DLL.

At least not in the general case.  In theory, we could implement it like
this:  If the target is a fs, treat the junction like a mount point (aka,
transparently as a normal directory), otherwise, if the target is a
directory, treat the junction as a symlink.

However, this is complicated, time consuming and error prone.  I can easily
imagine that this behaviour results in a strange, unexpected behaviour for
some people.

As a side note, I must admit that I was very excited when I heard about
reparse points for the first time when Win2K was in Beta stage.  Back then,
it sounded like the kitchen sink for getting rid of drive letters and to
allow mounts and symlinks being implemented transparently throughout Cygwin
and Win32 native apps.  Well, reality catched up pretty quickly...


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

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