newsyslog(8) patch for both size and time checks

Garance A Drosehn gad at
Thu May 14 20:53:47 UTC 2009

     [I wrote this yesterday, but apparently I then miniaturized
      the window instead of posting it...]

At 11:45 AM +0400 5/13/09, Dmitry Morozovsky wrote:
>On Tue, 12 May 2009, Garance A Drosehn wrote:
>GAD> > for now, if log is configured to be rotated in time manner, its
>GAD> > size is not checked,
>GAD> > so /var/log may be DoSed by some service (in our case, it was
>GAD> > mad DHCP client which fills up our /var/log with dhcpd log; our
>GAD> > newsyslog.conf line was
>GAD> >
>GAD> > /var/log/dhcpd				640  5     5000	@T00	JC
>GAD> >
>GAD> > The following simple patch should fix the problem. Any objection to
>GAD> > commit
>GAD> > this?
>GAD> It would fix your problem, but it changes the behavior as is explicitly
>GAD> documented in  'man newsyslog.conf' .  There is a paragraph in the man
>GAD> page which makes it clear that if both fields are specified, then the
>GAD> log file will only be rotated if both conditions are true.
>Nope, there is statement about time/interval combination, and size is not
>== 8< ==
>When both a time and an interval are specified then both conditions
>must be satisfied for the rotation to take place.
>== 8< ==

Admittedly I did look at that and read it wrong, but there is also:

     If a time is specified, the log file will only be trimmed if
     newsyslog(8) is run within one hour of the specified time.

>Also, I can't find anything about expected behaviour in the standards...

Well, it's a BSD program.  I wouldn't expect to see anything about it
in any standards writeup!

>GAD> I agree that newsyslog needs some way to specify an "either/or"
>GAD> combination of those fields.  I believe I have some time to look
>GAD> into changes to newsyslog right this week, so I'll see what is
>GAD> needed to address this issue.
>Thank you for looking into this.

The behavior you want is something many people (including me!) have
wanted, and it is something we should add.  I could have sworn there
was an undocumented way to get this behavior, but I recently tried
what I thought that method was, and it doesn't seem to work.

Garance Alistair Drosehn     =               drosehn at
Senior Systems Programmer               or   gad at
Rensselaer Polytechnic Institute;             Troy, NY;  USA

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