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Date: Thu, 6 May 2010 10:41:02 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: V1.7 and endless loops triggerd by junction points
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On May  5 21:15, Matthias Meyer wrote:
> Corinna Vinschen wrote:
> > Otherwise, the only difference as far as I can see is the fact that the
> > user token attrib inherited from the Cygwin shell has more user rights
> > enabled.  Namely the backup and restore rights, which allows to access
> > files and directories which are not available by default.  However, this
> > only works in an elevated shell, too.
> > 
> > However, it's not Cygwin's fault that attrib is not up to speed with
> > circular symlinks on an OS which allows them.
> > 
> It seems to be the backup and restore rights. I can run a cmd as
> administrator and attrib don't run into the endless loop.
> Also I can run sh from a normal user and attrib will work right.
> Only if I run attrib within a process with the backup and restore rights
> attrib will run into this endless loop :-(

There's a workaround for you, the cygdrop tool, part of the cygutils
package.

Here's an example:

  elevated bash$ cd /cygdrive/c/Users/All\ Users

  elevated bash$ attrib Desktop
      HR       C:\ProgramData\Desktop

  elevated bash$ attrib Desktop\\Cygwin.lnk
  A            C:\ProgramData\Desktop\Cygwin.lnk

  elevated bash$ cygdrop -p SeBackupPrivilege /cygdrive/c/Windows/System32/attrib -p Desktop\\Cygwin.lnk
  File not found - Desktop\Cygwin.lnk

Unfortunately you have to use the full path to attrib to make it work
since cygdrop doesn't perform a path search.

Still, it's Windows' own attrib command which fails because it doesn't
take extended user rights into account.  That's a bug in attrib, not
in Cygwin.


Corinna

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

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