>Number:         24381
>Category:       misc
>Synopsis:       Strange definitions of UID_MAX/GID_MAX and comments
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 10 17:05:00 UTC 2004
>Closed-Date:
>Last-Modified:
>Originator:     Christian Biere
>Release:        NetBSD 1.6ZH
>Organization:
>Environment:
System: NetBSD cyclonus 1.6ZH NetBSD 1.6ZH (STARSCREAM) #0: Fri Feb 6 00:16:58 CET 2004 root@cyclonus:/usr/src/sys/arch/i386/compile/STARSCREAM i386
>Description:

sys/sys/syslimits.h:
#define GID_MAX            2147483647U  /* max value for a gid_t (2^31-2) */
#define UID_MAX            2147483647U  /* max value for a uid_t (2^31-2) */

2147483647U is actually 2^31-1, not 2^31-2. This was already noticed by
Geoff Wing back in 1999:
http://mail-index.netbsd.org/current-users/1999/01/07/0002.html

Note the original commit message by Luke Mewburn:
-------
Revision 1.14, Thu May 22 03:02:50 1997 UTC (6 years, 8 months ago) by lukem
Branch: MAIN
Changes since 1.13: +3 -1 lines

define GID_MAX (max value permitted in gid_t) and UID_MAX (ditto for uid_t)
to 2^32-2
-------

Both were defined to 4294967294 as claimed in this message.

Here's his following commit message:
-------
Change {UID,GID}_MAX from 2^32-2 to 2^31-2 (which was the original
intention). This is because setreuid takes signed ints, which may
be -1 to indicate ``don't change [ug]id''.
-------

There are two mistakes. (-1) is 2^32-1 as long as we're at talking about
uint32_t (which is what uid_t and gid_t effectively are) but never 2^31-2.
I cannot see where setreuid uses signed ints, either. It never did, CMIIW.
The only reserved value (internally) is (-1) which is (2^32)-1
(sys/kern/kern_prot.c). So the intial commit was correct and the next was
caused by a misconception.

>How-To-Repeat:
>Fix:

Correct at least the comments to reflect reality and correct the values as
well if there aren't any obstacles.
>Release-Note:
>Audit-Trail:
>Unformatted: