tzsetup: add baseline file to control parsed zonetab contents

[yuripv]

Summary

Introduce undocumented option -d to dump parsed zonetab file contents
and add a "baseline" target along with instructions.

Baseline file is not installed in the system, and serves only as a check for when zoneinfo or tzsetup is updated.

Do this before changes in D39606 land to make sure it doesn't break anything it's not supposed to.
Intended to catch unexpected changes (like Iceland being listed under Africa that D39606 should fix).

[philip]

I like this idea, but I don't think this should live under /usr/share/zoneinfo. I believe that zoneinfo should *only* contain files generated by tzdata.

Maybe this should live in /usr/share/misc instead?

Also: please take a look at what upstream has done to their tzselect since the Great Merging (groan) of historical time zone data a couple of years ago. Perhaps our tzsetup can pick up some of those changes?

[yuripv]

In D39634#902042, @philip wrote:

I like this idea, but I don't think this should live under /usr/share/zoneinfo. I believe that zoneinfo should *only* contain files generated by tzdata.

Maybe this should live in /usr/share/misc instead?

I don't intend to install the file, it should only exist in src tree and serve as a check when updating zoneinfo (check that tzsetup is still able to parse it) or tzsetup (check that it didn't introduce unwanted changes).

Also: please take a look at what upstream has done to their tzselect since the Great Merging (groan) of historical time zone data a couple of years ago. Perhaps our tzsetup can pick up some of those changes?

D39606 is a result of running tzselect and being confused about how does it know to list Iceland properly under Atlantic while zone1970.tab says it's in Africa :)

[yuripv]

• make -d take path to zonetab file, so that baseline target uses the zone1970.tab in src and not from installed system
• update summary to explain why ${SRCTOP}/share/zoneinfo location

[yuripv]

move baseline file to usr.sbin/tzsetup to not clobber seemingly unrelated share/zoneinfo

[yuripv]

fix uninitialized variable

[philip]

I think this looks good now. Thanks you!

[otis]

usr.sbin/tzsetup/baseline

543

Shouldn't this read Europe/Bratislava ?

[yuripv]

usr.sbin/tzsetup/baseline

543

That is what in zone1970.tab, this file only contains the parsed information and is NOT the source for anything (i.e. it was that way always once we started using zone1970.tab).