Ludovic =?UTF-8?Q?Court=C3=A8s?= writes: > > OTOH, on POSIX-conforming systems (which includes GNU/Linux, so it may > be the majority of systems in use), -1 may well be a valid UID/GID.
That's a bizarre statement. 3.428 User ID A non-negative integer that is used to identify a system user. When the identity of a user is associated with a process, a user ID value is referred to as a real user ID, an effective user ID, or a saved set-user-ID. chown(2) uses (uid_t)-1 and (gid_t)-1 as the "don't change" special values. So does setreuid(2)/setregid(2). setuid(-1) isn't documented as special. Trying it out, it seems to be treated as equivalent to setuid(1). Not what I expected, but it doesn't really support your "-1 is a valid uid" theory. -- Alan Curry
