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Date: Tue, 14 Feb 2012 16:17:45 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: File operations really slow in emacs
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On Feb 14 09:44, Ryan Johnson wrote:
> On 14/02/2012 8:52 AM, Corinna Vinschen wrote:
> >On Feb 14 08:37, Ryan Johnson wrote:
> >>>>>(\??\C:\cygwin\cygdrive,0x28BB68)
> >>>>   ^^^^^^^^^^^^^^^^^^^^^^^
> >>>>   This looks suspicious.  I assume you're suffering from SMB network
> >>>>   scanning.
> >>>is there a workaround? Neither "always run elevated" nor "always
> >>>keep all network drives mounted" seems like a reasonable
> >>>requirement
> >What are you expecting?  Was my reply in
> >http://cygwin.com/ml/cygwin/2012-02/msg00375.html not sufficient?
> The reply explains why running elevated avoids the problem --
> apparently a side-effect of Windows' user token handling.
> 
> It does not explain why it's a good idea to always run elevated to
> get a side effect that compensates for bad behavior which is
> arguably a bug (though that's what I'm doing right now for lack of a
> better option -- I often work off-grid, so I can't always have all
> network drives mapped).
> 
> AFAICT, `stat /cydrive` runs into trouble because it enumerates all
> drive letters using GetFileAttributes, and only counts local drives
> as "links" to the "directory" : 2 + ndrives - nfloppies - nnonlocal.

That's only for stat and, yes, that can be removed and the link
set to 1, as for disk-based directories.

But that's not all.  GetFileAttributes is called in readdir as well, and
if it works, the subsequent code tries to open the drive and fetch the
inode number.  The inode number is important because otherwise find(1)
and other tools might print confused warnings.

So, even if we fix fstat, it doesn't solve the problem for readdir.  The
GetFileAttributes call is obviously supposed to find out if the drive is
accessible.  If not, it's omitted from the cygdrive dir.  Unfortunately...

Does anybody know a system call which allows to fetch the network drive
state (connected/not connected) without a billion microsecond timeout?


Corinna

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

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