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Date: Wed, 9 Oct 2002 17:45:48 -0400 (EDT)
From: Mikhail Kruk <meshko@cs.brandeis.edu>
To: <freebsd-questions@freebsd.org>
Subject: setregid question
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I have the following program:

main()
{
   printf("uid: %d\n", getuid());
   printf("euid: %d\n", geteuid());

   system("/root/uid.sh");

   setreuid(geteuid());
   setregid(getegid());
   printf("uid: %d\n", getuid());
   printf("euid: %d\n", geteuid());

   system("/root/uid.sh");
}

where uid.sh runs 'id' command.
I make executable 
chown meshko a.out; chgrp meshko a.out ; chmod 6770 a.out

and when I run it I get the following output:

uid: 0
euid: 1001
uid=0(root) euid=1001(meshko) gid=0(wheel) egid=1001(meshko) 
groups=1001(meshko), 0(wheel), 2(kmem), 3(sys), 4(tty), 5(operator), 
20(staff), 31(guest)
uid: 1001
euid: 1001
uid=1001(meshko) gid=1001(meshko) groups=1001(meshko), 0(wheel), 2(kmem), 
3(sys), 4(tty), 5(operator), 20(staff), 31(guest)

It seems to do everything the way I expect it, except for the printout of 
the group membership. I'm trying to lower my real group id to my effective 
group id, and gid output reflects the change, but I still get the list of 
groups in which root it... How come?


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