[xymon] parsing bug in hobbit-clients.cfg

Henrik Størner henrik at hswn.dk
Mon Nov 22 22:52:00 CET 2010

In <4CE6A88E.3010004 at phys.ethz.ch> Elmar Heeb <heeb at phys.ethz.ch> writes:

>On 11/19/2010 12:53 PM, Elmar Heeb wrote:
>> Suppose you have the following entry in hobbit-clients.cfg:
>> HOST=blog.example.com,example.com
>> PROC apache
>> then the PROC test will be ignored for example.com. If the two hosts are
>> reversed, i.e.
>> HOST=example.com,blog.example.com
>> PROC apache
>> then the PROC test will be done for both hosts. I tried with a few
>> variations on this and it appears that any later string in the comma
>> separated list will be ignored if it is a substring of a string that
>> appeared earlier. The same goes for EXHOSTS and probably most other
>> selectors.
>> This bug is present in at least versions 4.3.0 beta2 (from Debian
>> lenny-backports) and 4.2.0 (from Debian lenny).

>I have narrowed down the bug to the namematch subroutine in 
>lib/matching.c and attached a patch.

>The old code (which is the same in 4.2.0 and the svn trunk version) 
>indeed explains the wrong behaviour.  Lacking a preceeding comma as a 
>guard character essentially made any non-comma character a negating 
>match and not just an '!'.  The patch explicitly tests for ",%s," and 
>",!%s," and thus makes sure that a partial match cannot prevent a later 
>full match.

Thank You for a very detailed bug-report. Providing a simple testcase
was especially helpful. I considered using your suggested patch, but
instead decided to rewrite the routine since this turned out to be a
cleaner/simpler solution. So fixed in rev 6598.


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