Date: Sun, 21 Jan 2001 15:32:56 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Sergey Babkin <babkin@bellatlantic.net> Cc: Greg Black <gjb@gbch.net>, Neil Blakey-Milner <nbm@mithrandr.moria.org>, John Gregor <johng@vieo.com>, Gerhard.Sittig@gmx.net, leifn@neland.dk, freebsd-hackers@FreeBSD.ORG Subject: Re: how to test out cron.c changes? (was: cvs commit: src/etc crontab) Message-ID: <200101212332.f0LNWun16287@earth.backplane.com> References: <200101140244.f0E2i3518278@vieo.com> <3A621ABF.FA2C6432@bellatlantic.net> <200101142155.f0ELtLO64117@earth.backplane.com> <3A6A059C.486F6237@bellatlantic.net> <20010120235412.A42508@rapier.smartspace.co.za> <3A6B3D85.9773C9ED@bellatlantic.net> <nospam-3a6b44dfe00a3f3@maxim.gbch.net> <3A6B68E9.278A6BBB@bellatlantic.net>
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The problem here has nothing to do with whether changing the behavior
is good or bad, and everything to do with the fact that cron is an
absolutely critical core piece of software that runs on these machines
and there is no guarentee that you haven't introduced one or many bugs
with your rather large diff set. For better or for worse, people
already know about the daylight savings shift problem. Thousands
of people depend on cron to work, which means that when you
make a major change like this it must be tested by a wider audience
for a longer time before becoming the default. It needs to have some
real-life operational experience behind it.
So I have to say here that I agree with the calls to back it out...
it needs to backed out, and then put back in as a command line option.
Or you need to commit the command line option code ASAP and make the
old behavior the default. Judging by the diffs, it should not be
difficult for you to do this.
Also, I've already found a problem with the code:
+ /* check for the daylight saving time change
+ * we support only change by +-1 hour happening at :00 minutes,
+ * those living in more strange timezones are out of luck
+ */
+ if (last_time != 0 && tm->tm_isdst != lasttm.tm_isdst
+ && TargetTime > last_time /* exclude stepping back */) {
This is broken. If you want to check for a DLS change there is only
one right way to do it, and that is to compare the wall clock
differential verses the GMT differential, and to not put in any silly
restrictions like the change having to occur at the top of the hour
or be a +-1 hour increment. I would rather see the code ripped completely
out then to have a semi-broken DLS test.
-Matt
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