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Date: Wed, 15 Nov 2017 08:59:26 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: BSD file flags support in Cygwin?
Message-ID: <20171115075926.GL6054@calimero.vinschen.de>
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References: <D62F6895.F75A%billziss AT navimatics DOT com> <20171114100658 DOT GH6054 AT calimero DOT vinschen DOT de> <D6307C50.F768%billziss AT navimatics DOT com>
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On Nov 14 19:17, Bill Zissimopoulos wrote:
> Corinna, thanks for your answer.
>=20
> My question was largely to confirm my understanding as I probably do not
> have time to produce such a patch currently. For the benefit of the
> discussion and to assist any future attempts at doing this:
>=20
> Chflags(2) and friends would be relatively easy to implement. OTOH the
> BSD=E2=80=99s and OSX use stat(2) to report file flags in st_flags. Since=
 Cygwin
> lacks an st_flags field, we would have to somehow change struct stat to
> accommodate it. Do you have guidance on how to handle such a change? Would
> you even want such a change? [I suspect not.]

You're right.  Struct stat is exposed to user space so changing this is
bound to break existing applications.  We *might* get away lightly with
just adding a member to the end as in this case, but is the support for
DOS flags actually worth it?  It's still a hassle to support new and old
apps in Cygwin in such cases.

> [I know some OS=E2=80=99es have had to deal with stat(2) changes over the=
 years,
> but I am not as familiar with Cygwin history.]

An executable has the version info of the Cygwin version at the
time of building compiled in.  This is used in Cygwin to check
what an executable expects.

See winsup/cygwin/include/cygwin/version.h and the usage of the
checks throughout the code.


Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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