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Date:	Thu, 8 Apr 2021 23:28:26 +0300
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Subject:	Re: A problem with noacl+umask+chmod result
To:	cygwin AT cygwin DOT com
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From:	Orgad Shaneh via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Orgad Shaneh <orgads AT gmail DOT com>
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On Wed, Apr 7, 2021 at 11:47 PM Orgad Shaneh <orgads AT gmail DOT com> wrote:
>
> Hi,
>
> If a filesystem is mounted with noacl, calling chmod to add write
> permissions after umasking this permission doesn't work. Demonstrated
> with command-line and C++.
>
> Did I miss something or is this a real bug? According to umask man, it
> should only affect newly created files and directories, but I didn't
> find anything that relates to chmod.
>
> Command-line:
> touch foo
> ls -l foo
> # -rw-r--r-- ... foo
> umask 200
> chmod 0 foo
> ls -l foo
> # -r--r--r-- ... foo
> chmod 200 foo
> ls -l foo
> # -r--r--r-- ... foo
> # Expected to have rw

Marco Atzeri replied to the mailing list but did not CC me, so I
didn't receive it:

> without ACL you can not expect the POSIX scheme to properly work.
> see
> https://cygwin.com/cygwin-ug-net/ntsec.html
> to understand how Cygwin uses ACL to mimic POSIX permissions

Thanks Marco!

I'm well aware of that. I don't expect it to work properly. From what
I know, it can only set/unset user write bit. Read bits are always
enabled, even on chmod 0.

What I do expect is that the write bit will not be affected by umask.
umask should only affect newly created files, not direct chmod
commands.

- Orgad
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