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Reply-To: moss AT cs DOT umass DOT edu
Subject: Re: Permissions change concern
References: <5712F224 DOT 7070308 AT cs DOT umass DOT edu> <20160418101803 DOT GM24565 AT calimero DOT vinschen DOT de> <5714DDA9 DOT 3030002 AT cs DOT umass DOT edu> <20160418185553 DOT GB31378 AT calimero DOT vinschen DOT de>
To: cygwin AT cygwin DOT com
From: Eliot Moss <moss AT cs DOT umass DOT edu>
Message-ID: <5715448F.8080204@cs.umass.edu>
Date: Mon, 18 Apr 2016 16:33:19 -0400
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On 4/18/2016 2:55 PM, Corinna Vinschen wrote:
> On Apr 18 09:14, Eliot Moss wrote:
>> On 4/18/2016 6:18 AM, Corinna Vinschen wrote:
>>> On Apr 16 22:17, Eliot Moss wrote:

> Your example looks like 775.  But even then, the actual permissions
> depend on the mode bits given to the open(2) call, which are usually 666
> in this echo example.  The resulting perms should be 664.

Thank you -- I am convinced and agree, and that is what I get.

> Cygwin also takes the umask value into account if the newly created
> ACL only contains default POSIX permissions.  That's not quite correct
> in terms of POSIX 1003.1e draft 17, but in contrast to Linux, Windows
> directory ACLs practically always have default ACEs, so we have to
> compromise a bit, or umask just has no effect at all.  I fixed a
> problem with the permssion handling in case a mask value is present, but
> that shouldn't matter in your case.
>
>> 2) If the directory has g+s set (visible from -s- in the flags shown
>>     by getfacl), the directory's group is Cygwin, and my primary group is moss,
>>     then the file gets created with group moss, not group Cygwin (which is
>>     what g+s is supposed to mean, right?)
>
> There was still another bug in the same code snippet which disallowed to
> set the special POSIX bits S_ISVTX/S_ISGID/S_ISUID under some
> circumstances, but apart from that what you describe works for me if the
> bit is set in the parent dir and the parent dir inherits entries.
>
> But this only works if you create the file with a Cygwin executable and
> the parent dir has inheritable ACEs.
>
> I uploaded another snapshot to https://cygwin.com/snapshots/ to make
> sure the aforementioned bug can be tested as well.  Please check the
> latest snapshot again.
>
> However, if the s bit (aka S_ISGID) doesn't quite work as desired, I
> have to defer any solution (if possible) until after my vaca.

The g+s bit now works as I hoped/expected. Thanks!     E

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