svn commit: r277652 - in head/usr.sbin/pw: . tests

[Devin Teske]

> On Jan 25, 2015, at 7:31 AM, Bruce Evans <brde at optusnet.com.au> wrote:
> 
> On Sun, 25 Jan 2015, Slawa Olhovchenkov wrote:
> 
>> On Sun, Jan 25, 2015 at 04:56:24PM +1100, Bruce Evans wrote:
>> 
>>> Negative ids have historical abuses in places like mountd.

Which paves the way for the “accepted practice” argument
and backed up by “in-the-field usage” statement(s).



>>>  mountd still
>>> hard-codes -2 and -2 for the default uid and gid of an unprivileged user.
>>> It at least casts these values to uid_t and gid_t before using them.
>>> This gives the ids the non-random values of UINT32_MAX-1 if uid_t and
>>> gid_t are uint32_t.  (If uid_t and gid_t were signed, then it would
>>> leave the values as negative, so invalid.)  These magic values may work
>>> better than when ids were 16 bits, since there is less risk of them
>>> conflicting with a normal id.  However, the non-conflict is probably
>>> a bug.  FreeBSD uses the magic ids of 65534 for user nobody: group
>>> nobody.  These would have been (id_t)-2 with 16-bit ids.  They no
>>> longer match, so ls displays (id_t)-2 numerically.  FreeBSD also has
>>> a group nogroup = 65553 that doesn't match the nfs usage.  However2,
>>> in FreeBSD-1 wher ids were 16-bits, nobody was 32767 and nogroup was
>>> 32766. so they didn't match nfs for other reasons.  The 2 non-groups
>>> now seem to be just a bug -- FreeBSD-1 didn't have group nobody.
>>> 4.4BSD-Lite2 has the same values as FreeBSD-1.
>> 
>> This is not full true for ZFS case.
>> On ZFS nobody is 2^32-2.
> 
> File systems don't get to decide this.

+1 (and thanks for the historical account, bruce — sincerely)

However, I still want to make the argument that:

a. Because we’ve supported mapping negative inputs to unsigned values in pw *for over a decade*, that…

b. We should either revert or make a relnotes submission to note that we’re changing the long-standing accepted practice.

Changing the accepted practice broke code internally, it would have likely broken some external code as well — and people deserve to know about said change else we should continue to support accepted practice that is decade(s) old.
— 
Devin