[tz] [Tzdist] Regression Tests and Revision Controls

Lester Caine lester at lsces.co.uk
Wed Aug 13 07:10:32 UTC 2014

On 13/08/14 06:52, Paul Eggert wrote:
> Lester Caine wrote:
>> That we need to know which version of tz was used to normalize a record
>> has been a given
> Although it's been an assumption I doubt whether it's a given, as (A)
> the versioning is complicated, and (B) the version info is often not
> readily available.
> Here's a bit more about (A).  The tz database is typically massaged by
> downstream distributions before users see it.  Android discards all data
> outside the 32-bit window (roughly, before 1901 or after 2038).  Other
> distributions discard data before 1970, or add their own zones, or
> cherry-pick upstream changes, or invent their own changes.
> Here's an example of versions being distributed today.  Debian currently
> sports four distinct tzdata versions which it calls 2014e-0squeeze1,
> 2014e-0wheezy1, 2014e-1, and 2014f-1, each derived from an upstream
> release and with Debian-specific changes; see
> <https://packages.debian.org/search?keywords=tzdata>.  Ubuntu, which is
> downstream from Debian, currently has seven different versions with
> Ubuntu-specific changes, which it calls 2014e-0ubuntu0.10.04,
> 2014e-0ubuntu0.12.04, 2013b-1ubuntu1, 2013g-0ubuntu0.13.04,
> 2014e-0ubuntu0.13.10, 2014e-0ubuntu0.14.04, and 2014f-1; see
> <http://packages.ubuntu.com/search?keywords=tzdata>.  And Linux Mint,
> which is downstream from Ubuntu, has its own four versions 2010i-1,
> 2011n-0ubuntu0.11.10, 2013b-1ubuntu1, and 2014b-1; see
> <http://community.linuxmint.com/software/view/tzdata>.
> That's just three distributors; there are dozens more.  And if you care
> about Java, PHP, Go, etc., then multiply everything by another factor,
> as these subsystems have their own database copies with their own
> idiosyncrasies.  Good luck to anybody who wants to keep track of what
> all those versions actually mean.
> And that's just (A).  I suspect that (B) is a bigger kettle of fish.

All that just strengthens the argument for a properly managed
distribution system? And perhaps at the same time the major hole caused
by only providing a time offset in the browser header rather than a
users actual timezone can be address? It's not a lot of use giving
correct timezone data if you have no idea of the clients offset in 6
months time :(

Lester Caine - G8HFL
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