[Xymon] Bug in holidays calculation

[J.C. Cleaver]

On Tue, February 2, 2016 1:34 pm, Tom Schmidt (tschmidt) wrote:
> I have noticed a bug in the holidays feature of Xymon.  I am using Xymon
> 4.3.24 and have seen it on previous releases as well.  The issue is that
> the US Holiday of Thanksgiving is not showing the correct date during
> leap years.  Thanksgiving is the fourth Thursday in November, so is
> using this entry in holidays.cfg:
>
> Thanksgiving:type=thu month=11 offset=4
>
> This works correctly during non-leap years, but it is a day off during
> leap years like 2016.  I added these simple entries to holidays.cfg to
> better show the issue:
>
> November Week 1 Thu:type=thu month=11 offset=1
> November Week 2 Thu:type=thu month=11 offset=2
> November Week 3 Thu:type=thu month=11 offset=3
>
> When I look at the holidays that it calculates, I get this in the info
> column:
>
> Holidays 2015/2016 (USA)
> November Week 1 Thu	Nov 05
> November Week 2 Thu	Nov 12
> November Week 3 Thu	Nov 19
> Thanksgiving		Nov 26
> Christmas Day		Dec 25
> New Year's Day		Jan 01
> Easter Sunday		Mar 27
> Memorial Day		May 30
> Independence Day	Jul 04
> Labor Day		Sep 05
> November Week 1 Thu	Nov 03
> November Week 2 Thu	Nov 09
> November Week 3 Thu	Nov 16
> Thanksgiving		Nov 23
>
> Note that the November 2015 dates are correct, but the November 2016
> dates for Week 2 and later are a day early.  Thus it thinks Thanksgiving
> 2016 is on November 23 instead of the correct November 24 date.
>
> I looked at the source code some, but I could not follow the logic of
> how it is calculating this date incorrectly.  It is a minor bug only
> affecting those that use the holidays feature for alerts or look at the
> holidays table in the info tab.  Can someone figure out why it is not
> calculating the date offsets correctly?  It only seems to be doing this
> during leap years.
>
> Thanks...Tom


Hi,

This is definitely a bug in the holidays code; I think the *1st* X of the
month is being calculated OK, but others aren't... Unfortunately, my eyes
began to glaze over the further I got into mktime() response parsing :/

Looks like we had this issue four years ago too:
http://lists.xymon.com/archive/2012-January/033507.html


I'll see if I can take a closer look later on.

Regards,
-jc