Re: readonly, NTFS, and file metadata

[Earnie Boyd <earnie_boyd at yahoo dot com>]

Corinna Vinschen wrote:
> 
> 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???
> 

But, this only solves it for NTFS with ntsec set.  What about FAT?  I
think that it is wrong of automake maintainers to be so narrow minded. 
I plan to join that discussion.

Earnie.

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