utmp update for bsd systems (try 2)
t.d.lee at durham.ac.uk
Mon Apr 18 09:46:48 GMT 2005
On Sat, 16 Apr 2005, Michael Shalayeff wrote:
> Making, drinking tea and reading an opus magnum from Andrew Bartlett:
> -- Start of PGP signed section.
>> On Sat, 2005-04-16 at 07:18 -0400, Michael Shalayeff wrote:
>>> what is so "wrong" in it for you?
>>> maybe we can "fix" it...
>> I don't like such low-level messing with the utmp file. How does ftpd
>> on the BSDs handle utmp? This is the modal David Lee used originally, I
>> If the login() and logout() apis are not useful (has this been tested?),
>> can they be improved by the BSD crew to honour the contents of the
>> struct utmp?
>> Basically, I want anything that avoids doing a write() to those files
> i think i've figured out the difficult part for you.
> if you open the source and read it you would see that
> there are whole bunch of functions that use all kinds
> of so called high-leel apis to write into utmp that do
> exist on many operating systems. this particular function
> that is losely aimed for bsd support exists for the whole
> purpose for systems that lack such functions.
> that is it -- IT MUST BE LOW-LEVEL as you call it.
(By "open the source", I assume the source in questions is Samba's
I admit that I did insert hooks for direct file-writing if necessary.
But that was really only for last-resort, absence-of-anything-else,
purposes. And I admit that I made an association between these hooks and
possible need for their use on BSD, but based on a no-direct-experience
reading of the "utmp" man page, and over five years ago.
However, almost my first comment in the file, the first "Hints for
porting", strongly urges programmatic (perhaps a poorly chosen word) use
rather than direct file access. I stand by this strong preference, not
least because it should avoid (bugs notwithstanding) locking problems
with simultaneous update.
A reading of the BSD man pages (at "www.freebsd.org") for "login(3)" and
"logout(3)", suggests that this login/logout avenue looks reasonable for
further investigation. There seems nothing in the man page which says
that it has to be associated with a "tty". Of course, such investigation
might reveal a fundamental show-stopper along these (or other) lines for
such a login/logout implementation.
We're all agreed that a Samba/utmp interface on BSD is desirable. What it
now needs is someone with a test rig (BSD, Samba 3.0.x) to try to do the
best implementation. I would suggest that the login/logout route is
investigated first. If some reasons then emerge that can prove this to be
unworkable, then a fall-back direct file access method would seem to be
Michael: I've been, and, indeed, still am, where you are! A relative
"outsider" trying to get patches accepted by the Samba Team. It can seem
tedious. They do sometimes need reminding. But they are open to
well-reasoned suggestions. Samba is phenomenally impressive, not least in
its technical rigour and its high portability across a range of diverse OS
features and interfaces. To us, as outsiders, it can sometimes seem
annoying and frustating. But I can see, and understand, why they need to
do this to preserve the integrity, protability and functionality of Samba.
(Andrew and I have had our differences, haven't we?!)
Hope that helps.
: David Lee I.T. Service :
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