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From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.unix.wizards,comp.bugs.sys5
Subject: Re: setuid (euid) after setuid (uid) on System 5
Message-ID: <1212@auspex.UUCP>
Date: 26 Mar 89 01:25:05 GMT
References: <123@cat.Fulcrum.BT.CO.UK> <280@cbnewsc.ATT.COM> <1196@auspex.UUCP> <9915@smoke.BRL.MIL>
Reply-To: guy@auspex.UUCP (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 22

>>Both BSD and S5 flavors of "setuid" can be implemented atop "setreuid".
>
>I don't think the "saved set-UID" feature can be emulated using
>setreuid().

OK, let me state it better, making explicit an implicit part of my
statement:

	Both BSD and S5 flavors of "setuid" can be (and have been)
	implemented atop "setreuid" *if you put the saved set-UID
	feature into your system in the fashion described in my
	article in the parts preceding the statement.*

This isn't emulating the saved set-user ID feature using a vanilla
"setreuid"; it's emulating both the BSD and S5 behaviors of "setuid"
atop a "setreuid" that works with a saved set-user ID feature already in
the system.

>Maybe for 4.4BSD?

As I said, they may end up picking up a SunOS-style "saved set-user ID"
implementation (as I presume S5R4 will).