64-bit time_t and tz file format

John Cowan cowan at locke.ccil.org
Thu Jun 10 19:06:45 UTC 1999

alan perry wrote:

> A couple of days ago, I posted something to this list about how to
> go about changing the tz file format to support a 64-bit time_t
> value.  I have heard nothing back.

I've been thinking about the problem a bit, since I'm interested
in adapting the code to Java, which has a 64-bit millisecond
time count with the same epoch as Unix time_t.
> As I noted earlier, the current tz file format doesn't scale
> well to a 64-bit time_t and all of the possible additional timezone
> transitions that result from the addition years that can be
> represented.

Actually, the current format is quite suitable (doubling the
size of all time_t's in it, obviously).  It just becomes necessary
to drop the idea that timezone files are good from now until
the End Of Time.

The idea of setting an explicit expiration date has been around
for a while, but not IMHO implemented yet.  A 64-bit version of
zic can set the expiration date based on information in the
source files, or simply to some sufficiently remote date like
2100.  Time zone data changes fairly often anyway, and 2100 will
see most of us safely dead.  :-)

John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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