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Date: Sat, 29 Mar 2025 13:41:25 +0100
To: Bruno Haible <bruno AT clisp DOT org>, bug-gnulib AT gnu DOT org, cygwin AT cygwin DOT com
Subject: Re: symbolic link curiousity in 3.6.0
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From: Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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On Mar 29 13:12, Corinna Vinschen via Cygwin wrote:
> On Mar 29 12:43, Bruno Haible via Cygwin wrote:
> > OK, and what does this mean for the *files* created in such a directory?
> 
> Just for clarity, permissions in Windows are *always* defined by an ACL.
> There's no such thing as default POSIX perms.  Don't try to look at
> non-Cygwin-created files from a POSIX permission POV, it's a lost cause.
> 
> But your question was specificially about files created in the above
> dir:
> 
> - Files created by a Cygwin process inside that dir will have only the
>   usual three ACL entries constituting standard POSIX permission bits,
>   combined with their umask, i.e.:
> 
>   $ cd /tmp/glo1FkFx/tmpdir0
>   $ umask
>   22
>   $ touch foo
>   $ getfacl foo
>   # file: foo
>   # owner: corinna
>   # group: vinschen
>   user::rw-
>   group::r--
>   other::r--
> 
> - Files created by non-Cygwin processes inside that dir will have by
>   default(*) only the usual three ACL entries constituting standard
>   POSIX permission bits, but there's no umask handling in the non-Cygwin
>   process, i.e.
> 
>   $ cd /tmp/glo1FkFx/tmpdir0
>   $ cmd
>   C:\cygwin64\tmp\glQatIoG\tmpdir0>echo foo > bar
>   C:\cygwin64\tmp\glQatIoG\tmpdir0>exit
>   $ getfacl bar
>   # file: bar
>   # owner: corinna
>   # group: vinschen
>   user::rwx
>   group::r-x
>   other::r-x
> 
>   (*) Most Windows processes rely entirely on the permissions in
>   the ACLs and the Windows ACL inheritance rules.
> 
> Does that answer your question?
> [...]
> For non-Cygwin-generated files, there's no such thing as a standard ACL,
> and the Cygwin user, looking from the POSIX perspective when using it,
> should see the '+'-sign to notice this file has no POSIX permissions.

Erm... except for non-Cygwin-generated files created in a Cygwin-created
dir, as outlined in the above example, in which case the inherited
default permissions emulate POSIX permissions and acl_extended_file() on
them returns 0.

I wasn't sure this was clear from the example...


Corinna

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