[Patch] BZ#14080: Fix daylight time change for the US

[Joseph S. Myers]

On Thu, 10 May 2012, Roland McGrath wrote:

> I think the ideal implementation-defined resolution for us would be to use
> something table-driven for this case.  That is, "TZ=fooNbar" would obey the
> N, the "foo", and the "bar", but refer to some canonical tzdata file for
> the rules to follow.  Given the style of the tzdata format I'm not sure

As I understand it, that's what the code does (file "posixrules").

> exactly how this would work.  Perhaps it's as simple as computing a bias to
> apply to the transition times in the file, which would mean that we encode
> both a canonical tzdata file name and the knowledge of what that file's
> baseline GMT offset is (i.e. "US/Eastern" and 5 hours west).  Of course,
> we'd still need a fallback when the file is not found.  But at least in the
> normal case we wouldn't be relying on library or program binaries made long
> ago to encode rules that can change over time.

And I thought this code was just that fallback if "posixrules" is missing.

-- 
Joseph S. Myers
joseph@codesourcery.com