[tz] tzfiles contain Unix epoch for the first transition time

Robert Elz kre at munnari.OZ.AU
Fri Aug 14 14:14:29 UTC 2015

    Date:        Fri, 14 Aug 2015 12:55:20 +0100
    From:        Ian Abbott <abbotti at mev.co.uk>
    Message-ID:  <55CDD728.7040401 at mev.co.uk>

  | If the initial transitions are also missing in Eric's tzfiles, perhaps 
  | the bug is related to that.

Actually, given the values that Paul reported, I suspect the bug might be
in the code that's reading the files - the epoch result reported looks
like something is not using all 64 bits of the values - somehow dropping
the top 8 (or more) bits, which would make the big bang timestamp look like 0.

It must be using more than 32 bits though, otherwise it couldn't get the
1883 value - but it only needs to be using 33 bits for that one to work.

Perhaps some range check is happening, to keep the years within 32 bit
signed numbers?

Or maybe the top 32 bits are being used only to set the sign for an
unsigned bottom 32 bit value - that would produce the results indicated.
(for the big bang value, the sign would be negative, but the value is 0,
so it wouldn't affect anything.)


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