You have to chmod it to the correct group afterwards. It's a standard that
when a file is created it gets the same group as the parent directory. So
just chmod the file :-)

Douwe

----- Original Message -----
From: "Jorgen Lundman" <lundman@lundman.net>
To: <netbsd-users@netbsd.org>
Sent: Monday, April 21, 2003 8:03 AM
Subject: setegid() magic..


>
> Just out of curiosity,
>
> If I write a piece of code, run as root, or setuid root, that does:
>
>     unlink("testfile");
>     seteuid(10000);
>     F=fopen("testfile", "w");
>
> It creates the file as the user I want. Now I also want to do the same
with
> groups, so we add:
>
>     unlink("testfile");
>     setegid(10001);
>     seteuid(10000);
>     F=fopen("testfile", "w");
>
> It creates the file as 10000, but the group is "wheel". Or to be precise,
it is
> the same group as "." of the directory.
>
> Is there a way that I can "become" the user "properly" so items are
created both
> as user 10000 and group 10001?
>
> I've tried sticking
>
>     gid_t p = 10001;
>     unlink("testfile");
>     setegid(10001);
>     setgroups(1, &p);
>     seteuid(10000);
>     F=fopen("testfile", "w");
>
> Which made no difference, however, in the last example, if I stick
>    fchown(fileno(F), -1, 10001);
>
> .. after the fopen then it works in that I am now allowed to chgrp the
file (as
> user 10000) to 10001. But it would be nice to become a user, then have all
> open/fopen etc calls just create it the files as I wanted (10000,10001).
>
> Oh and it makes no difference if I use 10001 that isn't in /etc/group, or
gid
> 20, that is in /etc/group.
>
> I could also seteuid; fopen; seteuid(root); chown(uid,gid).  But wonder if
there
> was a better way.
>
> Lund
>
>
>
>
> --
> Jorgen Lundman       | <lundman@lundman.net>
> Unix Administrator   | +81 (0)3 -5456-2687 ext 1017 (work)
> Shibuya-ku, Tokyo    | +81 (0)90-5578-8500          (cell)
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>
>