Re: [TESTERS needed] New POSIX permission handling

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

Hi Ismail,

On Apr 12 16:25, Corinna Vinschen wrote:
> On Apr 12 06:21, Äsmail DÃnmez wrote:
> > Corinna Vinschen-2 wrote
> > > On Apr 11 10:11, donmez wrote:
> > >> Corinna Vinschen-2 wrote
> > >> > I just applied a patch I'm working on for quite some time now.  As I
> > >> > outlined before on this list, the POSIX permission handling has aged
> > >> > considerably and, for historical reasons, did things differently
> > >> > dependent on the calling function.  I took the time to reimplement the
> > >> > core functionality to handle all ACLs as strictly following POSIX ACL
> > >> > rules as possible.
> > >> 
> > >> I tested the updated package and at least quilt and mutt seems to broken
> > >> by
> > >> the permission changes:
> > >> [...]
> > > No offense, but this is not overly helpful.  The problem is to learn
> > > *why* this happens and how to fix it.  For that I'd need to know what
> > > your permissions on /tmp look like (ls -l, getfacl, icacls).  Creating
> > > files in my /tmp (having an old-style ACL) with the following
> > > permissions works as desired for me:
> > 
> > Hopefully this will shed some more light:
> 
> It does, thank you.  The problem is the dreaded "owner == group" problem
> introduced with these weird Microsoft accounts.  I completely forgot
> about this while implementing the new code.  It's pretty tricky to get
> the Windows ACL right for this.  Additionally the ACLs already created
> by setup are... borderline correct only.  Back to the drawing board...

I just applied a patch which is supposed to handle this owner==group
scenario better.

In short, Cygwin will try to handle POSIX user and group permissions
separately, even if owner == group.  This is basically a fake as far
as the actual permissions of the account are concerned, but it allows
applications still to chmod to different user and group perms.  It
just *looks* different in the end.

The only restriction of this is that the POSIX user permissions are
always changed so that the user perms are >= the group perms in this
situation.  So this:

  chmod 460 foo

will be internally twisted into

  chmod 660 foo


I uploaded new developer snapshots to https://cygwin.com/snapshots/
and I'm just uploading a 2.0.0-0.5 test release with this change.

Please give either of them a try.  I'd be interested in feedback,
ideally with details if something doesn't work as desired.


Thanks,
Corinna

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

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