Weirdest bug yet.

Eric S. Raymond esr at thyrsus.com
Thu Jul 7 03:59:24 UTC 2016


OK, this is officially bizarre.

Earlier this evening I got a report from Gary that ntpd wasn't logging
peerstats.  I'd just done a significan change to logging ("More
magic-address banishment.) so I hastily reverted that. Then tested -
still no good, no peerstats.

Picking an arbitrary revision a couple weeks back, I verified that it
emitted peerstats and bisected.  To make a long story short, I did find the
change that broke peerstats logging.

It was adding "subtype" as an alias for "mode" in the lexical analyzer.
This somehow confuses the crap out of the parser's FSM. Even though
neither "subtype" nor "mode" occurs anywhere near the relevant productions
(sttistics and filegen) and those tokens don't even share a prefix with
anything that does.

It looks like my ability to modify the configuration grammar has some
hidden limits due to bugs or undocumented features of the lexical analyzer 
generator,
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>


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