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Date: Mon, 22 Jan 2007 14:29:34 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: "id -Gn" w/ username doesn't return all associated groups.  Issue  with getgrent()?
Message-ID: <20070122132934.GU27843@calimero.vinschen.de>
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References: <001a01c73dae$7dec4af0$6152a8c0 AT ziesemermark> <20070122093419 DOT GR27843 AT calimero DOT vinschen DOT de> <45B4B622 DOT 9040406 AT byu DOT net>
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On Jan 22 06:03, Eric Blake wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> According to Corinna Vinschen on 1/22/2007 2:34 AM:
> >> When "id" is called without a username, it calls the getgroups(...) function
> >> which appears to work as expected.  However, when a specific username is
> >> passed, even the username of the current user, getugroups(...) is called,
> >> and does _not_ appear to work as expected.
> > 
> > That's by design.  getgroups() has access to the user token of the
> > current process and returns every group which is in this token.
> > getgrent() is a function which enumerates /etc/groups.
> 
> So my translation of this would be that the bug is not in id, but in the
> fact that your /etc/groups is out-of-date.  Use mkgroups to remedy the
> situation.

A little bit more specific:  Use the mkgroup -u flag.  By default,
mkgroup does not add the users to the gr_mem field since that's not
necessary for correct operation of setuid(2).  By adding the users
to the gr_mem field (the -u option), you probably get what you want.


Corinna

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

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