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Date: Tue, 14 Aug 2001 12:10:21 +0200
From: Corinna Vinschen <vinschen AT redhat DOT com>
To: cygwin-developers AT cygwin DOT com
Subject: Re: readonly, NTFS, and file metadata
Message-ID: <20010814121021.E17709@cygbert.vinschen.de>
Reply-To: cygdev <cygwin-developers AT cygwin DOT com>
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References: <3B783E6E DOT 2546DF0 AT ece DOT gatech DOT edu> <20010814120018 DOT D17709 AT cygbert DOT vinschen DOT de>
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In-Reply-To: <20010814120018.D17709@cygbert.vinschen.de>; from vinschen@redhat.com on Tue, Aug 14, 2001 at 12:00:18PM +0200

On Tue, Aug 14, 2001 at 12:00:18PM +0200, Corinna Vinschen wrote:
> On Mon, Aug 13, 2001 at 04:54:06PM -0400, Charles Wilson wrote:
> > There is an ongoing thread on the automake list (started by yours truly,
> > agent provocateur) concerning some strangeness I've encountered on
> > NTFS(ntsec), with 'cp -p' and readonly files.  The URL for the beginning
> > [...]
> > What happens is this: first, foo is copied to bar, with perms
> > -r--r--r--.  But, the timestamp is wrong.  Since cp was called with
> > '-p', cp then tries to set the timestamp of bar to match foo.  But it
> > can't on cygwin.  On linux, it can.
> > 
> > My suggestion to the automake list, which was to make foo be -rw-r--r--,
> > was not well received.  The suggestion in return was: make cygwin act
> > like linux.  I can't really argue against that, since that's been our
> > stated goal anyway.
> > 
> > Does anybody know offhand what it would take to 'linux-ize' this
> > behavior (e.g. would we have to take a performance hit?)  Do we want to
> > be like linux in this particular? Also, please check the thread
> > referenced above.
> 
> Check return code of SetFileTime(), check if ntsec ON and
> file is on NTFS, get current ACL, modify to have write_data
> access for current user, call SetFileTime() again, reset ACL.
> 
> The only problem is that we need a new function set which
> _exactly_ saves and restores a given ACL and another function
> which exactly adds write access to the current user. The
> standard functions in security.cc are not appropriate.

Wait, that's not quite true. read_sd() and write_sd() are
the functions to save and restore a SD. So there's only
a function to set write access for the current user missing...

Is it true that the problem can be restricted to files
which are actually owned by the current user???

Corinna

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