[Devel] Re: [PATCH 4/6] BC: user interface (syscalls)

[Alexey Dobriyan]

On Thu, Aug 24, 2006 at 12:04:16PM +0100, Alan Cox wrote:
> Ar Mer, 2006-08-23 am 21:35 -0700, ysgrifennodd Andrew Morton:
> > > Its a uid_t because of setluid() and twenty odd years of existing unix
> > > practice.
> > >
> >
> > I don't understand.  This number is an identifier for an accounting
> > container, which was somehow dreamed up by userspace.
>
> Which happens to be a uid_t. It could easily be anyother_t of itself and
> you can create a container_id_t or whatever. It is just a number.
>
> The ancient Unix implementations of this kind of resource management and
> security are built around setluid() which sets a uid value that cannot
> be changed again and is normally used for security purposes. That
> happened to be a uid_t and in simple setups at login uid = luid = euid
> would be the norm.
>
> Thus the Linux one happens to be a uid_t. It could be something else but
> for the "container per user" model whatever a container is must be able
> to hold all possible uid_t values. So we can certainly do something like
>
> typedef uid_t	container_id_t;

What about cid_t? Google mentions cid_t was used in HP-UX specific IPC (only if
_INCLUDE_HPUX_SOURCE is defined).