X-Recipient: archive-cygwin AT delorie DOT com
X-Spam-Check-By: sourceware.org
Date: Thu, 26 Feb 2009 12:05:20 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: special name for vss shadow copy device?
Message-ID: <20090226110520.GW18319@calimero.vinschen.de>
Reply-To: cygwin AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
References: <87f94c370902241242q78d0d068o4416b4ae2aa9be62 AT mail DOT gmail DOT com> <49A59485 DOT 8090401 AT t-online DOT de> <87f94c370902251121s12579193q3032a5ce7cdef685 AT mail DOT gmail DOT com> <49A5CDDE DOT 4040703 AT cygwin DOT com> <87f94c370902251620h746060f8j4137fa5c3747e6e4 AT mail DOT gmail DOT com> <20090226091054 DOT GS18319 AT calimero DOT vinschen DOT de>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20090226091054.GS18319@calimero.vinschen.de>
User-Agent: Mutt/1.5.19 (2009-02-20)
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
Precedence: bulk
List-Id: <cygwin.cygwin.com>
List-Unsubscribe: <mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

On Feb 26 10:10, Corinna Vinschen wrote:
> On Feb 25 19:20, Greg Freemyer wrote:
> > On Wed, Feb 25, 2009 at 6:01 PM, Larry Hall (Cygwin)
> > <reply-to-list-only-lh AT cygwin DOT com> wrote:
> > > Greg Freemyer wrote:
> > > <snip>
> > >
> > >> Time to experiment with Cygwin 1.7
> > >>
> > >> I know the whole package is still considered test.  How stable is the
> > >> actual dll(s).  Especially as relates to this type of functionality.
> 
> The DLL is quite stable but there are certainly some bugs as well.
> 
> > I tried the "dosdev" trick from one of the links to mount the snapshot
> > as V:.  Apparently that is a XP only trick.  Or at least Vista does
> > not have it.

Here's how it does NOT work:

  $ dosdev 'V:' '\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy21'
  $ mount
  [...]
  C: on /cygdrive/c type ntfs ...
  $

  The reason is that the path the drive points to has to be a native NT
  path.  The path containg the GLOBALROOT is a long Win32 path name which
  is invalid in this case.  However, the dosdev functionality is nothing
  but creating a symbolic link in the native NT namespace and the target
  of such a symlink can be anything which can be expressed in a 64K buffer.

Here is how it works:

  $ dosdev 'V:' '\Device\HarddiskVolumeShadowCopy21'
  $ mount
  [...]
  C: on /cygdrive/c type ntfs ...
  V: on /cygdrive/v type ntfs ...

  What you have to do is to create a native NT symlink which points
  to the actual native NT device name which is as shown above, just
  \Device\HarddiskVolumeShadowCopy21.

  That works like a champ on Cygwin and in Windows Explorer on Vista.

Btw., I'm using my own crude dosdev:

======================================================================
#include <stdio.h>
#include <windows.h>

int
main (int argc, char **argv)
{
  DWORD flags = 0;

  if (argc < 2)
    {
      fprintf (stderr, "usage: %s DosDevice [NTDevice]\n", argv[0]);
      return 1;
    }
  if (argc == 2)
    flags = DDD_REMOVE_DEFINITION;
  else
    flags = DDD_RAW_TARGET_PATH;
  if (!DefineDosDevice (flags, argv[1], argc == 2 ? NULL : argv[2]))
    {
      fprintf (stderr, "Error %d\n", GetLastError ());
      return 1;
    }
  return 0;
}
======================================================================

$ gcc -o mydosdev mydosdev.c
$ # Create the dos link
$ ./mydosdev 'V:' '\Device\HarddiskVolumeShadowCopy21'
$ # Remove it
$ ./mydosdev 'V:'                                       


HTH,
Corinna

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

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/