From: Paul Eggert <eggert@cs.ucla.edu>
To: "Đoàn Trần Công Danh" <congdanhqx@gmail.com>,
"Russ Allbery" <eagle@eyrie.org>
Cc: musl@lists.openwall.com, tz@iana.org
Subject: [musl] Re: [tz] Weird PST8PDT and EST5EDT behavior on Alpine Linux
Date: Mon, 4 Mar 2024 20:31:58 -0800 [thread overview]
Message-ID: <0620fe7a-d3e7-42a0-b65e-f61979cacd22@cs.ucla.edu> (raw)
In-Reply-To: <ZeaW91rIn9kkNR0V@danh.dev>
On 3/4/24 19:52, Đoàn Trần Công Danh via tz wrote:
> But seems like nothings was enforced if rule isnot given in the
> timezone, which makes it open to intepretion.
>
> Musl inteprete that as no transition at all [2].
Thanks, that explains things. TZDB has a TZDEFRULESTRING setting that
specifies the transitions in this situation; it defaults to US rules, so
musl and TZDB always disagree about TZ settings like TZ='PST8PDT'.
In TZDB, though, TZDEFRULESTRING is not used for PST8PDT and EST5EDT, as
these are one of a small set of Zones that emulate the old System V
behavior except with later US law changes taken into account.
Another way to put it: for musl the two settings TZ='PST8PDT' and
TZ='pst8pdt' agree except for the case of time zone abbreviations, and
neither TZ setting ever uses daylight saving time.
For TZDB, though, those two TZ settings agree only back to 2007; for
earlier timestamps, TZ='PST8PDT' follows historical US behavior for
standard time (and thus agrees with TZ='America/Los_Angeles' for all
timestamps after 1883-11-18 at noon) whereas TZ='pst8pdt' disagrees with
historical behavior by assuming current (2007 and later) rules for DST
transitions before 2007.
These behaviors all conform to POSIX.
next prev parent reply other threads:[~2024-03-05 4:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87edcqv69m.fsf@hope.eyrie.org>
2024-03-05 3:52 ` Đoàn Trần Công Danh
2024-03-05 4:31 ` Paul Eggert [this message]
2024-03-05 20:12 ` Rich Felker
2024-03-05 20:56 ` Russ Allbery
2024-03-05 21:37 ` [musl] Re: [tz] [musl] " Guy Harris
2024-03-05 22:03 ` Russ Allbery
2024-03-05 22:12 ` Guy Harris
2024-03-05 22:31 ` Russ Allbery
2024-03-06 15:39 ` James Cloos
2024-03-08 17:46 ` [musl] Re: [tz] " Paul Eggert
2024-03-08 19:02 ` Rich Felker
2024-03-09 0:09 ` James Cloos
2024-03-09 1:57 ` [musl] Re: [tz] [musl] " Guy Harris
2024-03-08 18:39 ` Guy Harris
2024-03-08 19:05 ` [musl] Re: [tz] " Paul Eggert
2024-03-09 0:03 ` [musl] " James Cloos
2024-03-06 0:47 ` [musl] Re: [tz] " Paul Eggert
2024-03-06 1:54 ` Rich Felker
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