FW: tz interface problems

Olson, Arthur David OLSONA at dc37a.nci.nih.gov
Wed May 20 13:47:42 UTC 1998

From: 	D. J. Bernstein[SMTP:djb at cr.yp.to]
Sent: 	Monday, May 18, 1998 3:32 AM
To: 	arthur_david_olson at nih.gov; djb at cr.yp.to
Subject: 	tz interface problems

1. Check out the dates produced by sendmail on one host:

   Mon, 18 May 1998 16:36:37 +0930
   Mon, 18 May 1998 16:36:38 +0930
   Mon, 18 May 1998 16:36:39 +0929
   Mon, 18 May 1998 16:36:40 +0929

The problem, of course, is that sendmail is figuring out the offset by
comparing the hours and minutes shown by localtime() and gmtime().

Mailers don't care about time zone names; they want the UTC offset. Do
you have a routine that, given a time, returns the offset? (1-second
offsets can't be expressed in mail, but that's a separate problem.)

2. I'm sure you're aware that BSD and Linux now include your routines.
Unfortunately, they don't make it easy for typical users to regenerate
the time-zone files. Users could download new files, but that's a
megabyte of data.

The practical effect is that many systems slipped by a second in 1997,
and will probably slip by another second at the end of 1998.

How difficult would it be for you to get leap-second data from another
file? I've been working on the Y2038 problem, and I've put together an
/etc/leapsecs.dat format for recording leap seconds.


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