[tz-announce] 2025a release of tz code and data available

Jan. 16, 2025

      The 2025a release of the tz code and data is available.

This release contains the following changes:

   Briefly:
     Paraguay adopts permanent -03 starting spring 2024.
     Improve pre-1991 data for the Philippines.
     Etc/Unknown is now reserved.

   Changes to future timestamps

     Paraguay will stop changing its clocks after the spring-forward
     transition on 2024-10-06, so it is now permanently at -03.
     (Thanks to Heitor David Pinto and Even Scharning.)
     This affects timestamps starting 2025-03-22, as well as the
     obsolescent tm_isdst flags starting 2024-10-15.

   Changes to past timestamps

     Correct timestamps for the Philippines before 1900, and from 1937
     through 1990.  (Thanks to P Chan for the heads-up and citations.)
     This includes adjusting local mean time before 1899; fixing
     transitions in September 1899, January 1937, and June 1954; adding
     transitions in December 1941, November 1945, March and September
     1977, and May and July 1990; and removing incorrect transitions in
     March and September 1978.

   Changes to data

     Add zone1970.tab lines for the Concordia and Eyre Bird Observatory
     research stations.  (Thanks to Derick Rethans and Jule Dabars.)

   Changes to code

     strftime %s now generates the correct numeric string even when the
     represented number does not fit into time_t.  This is better than
     generating the numeric equivalent of (time_t) -1, as strftime did
     in TZDB releases 96a (when %s was introduced) through 2020a and in
     releases 2022b through 2024b.  It is also better than failing and
     returning 0, as strftime did in releases 2020b through 2022a.

     strftime now outputs an invalid conversion specifier as-is,
     instead of eliding the leading '%', which confused debugging.

     An invalid TZ now generates the time zone abbreviation "-00", not
     "UTC", to help the user see that an error has occurred.  (Thanks
     to Arthur David Olson for suggesting a "wrong result".)

     mktime and timeoff no longer incorrectly fail merely because a
     struct tm component near INT_MIN or INT_MAX overflows when a
     lower-order component carries into it.

     TZNAME_MAXIMUM, the maximum number of bytes in a proleptic TZ
     string's time zone abbreviation, now defaults to 254 not 255.
     This helps reduce the size of internal state from 25480 to 21384
     on common platforms.  This change should not be a problem, as
     nobody uses such long "abbreviations" and the longstanding tzcode
     maximum was 16 until release 2023a.  For those who prefer no
     arbitrary limits, you can now specify TZNAME_MAXIMUM values up to
     PTRDIFF_MAX, a limit forced by C anyway; formerly tzcode silently
     misbehaved unless TZNAME_MAXIMUM was less than INT_MAX.

     tzset and related functions no longer leak a file descriptor if
     another thread forks or execs at about the same time and if the
     platform has O_CLOFORK and O_CLOEXEC respectively.  Also, the
     functions no longer let a TZif file become a controlling terminal.

     'zdump -' now reads TZif data from /dev/stdin.
     (From a question by Arthur David Olson.)

   Changes to documentation

     The name Etc/Unknown is now reserved: it will not be used by TZDB.
     This is for compatibility with CLDR, which uses the string
     "Etc/Unknown" for an unknown or invalid timezone.  (Thanks to
     Justin Grant, Mark Davis, and Guy Harris.)

     Cite Internet RFC 9636, which obsoletes RFC 8536 for TZif format.

Here are links to the release files:

   https://www.iana.org/time-zones/repository/releases/tzcode2025a.tar.gz
   https://www.iana.org/time-zones/repository/releases/tzdata2025a.tar.gz
   https://www.iana.org/time-zones/repository/releases/tzdb-2025a.tar.lz

The following convenience links are also available, although they may 
point to the previous release until the relevant caches are refreshed:

   https://www.iana.org/time-zones/repository/tzcode-latest.tar.gz
   https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz
   https://www.iana.org/time-zones/repository/tzdb-latest.tar.lz

Links are also available via plain HTTP, and via FTP from 
ftp://ftp.iana.org/tz/releases with the same basenames as above.

Each release file has a GPG signature, which can be retrieved by 
appending ".asc" to the above URLs. Copies of these signatures are 
appended to this message.

This release corresponds to commit 
a8e2fcd87bc5f83fec0a76652095e8d7881b0763 dated 2025-01-15 10:47:24 -0800 
and tagged '2025a' in the development GitHub repository at 
<https://github.com/eggert/tz>.

Here are the SHA-512 checksums for the release files:

308f6a3d6ebfa18446f8296e5c799e18dccecd79ace3ba004d3f233892c7428faae152b217b22d229c59dd4e0faafee797d8b3583b58fa982b81f7cc7347f502 
  tzcode2025a.tar.gz
93b8f939d39bdfe451e262666f9099c529c96c49d14c08e3611560ca660e12e16d08a22b145d615e00570fb194881618d6f9a0a617c119ab447be03279d747c3 
  tzdata2025a.tar.gz
1e8c4e141158d63ca5c39babc9d18c32df14e2e59bc7649a7fed8c3e577f7b175bafa43883cf351139ff198515f5f8c22b1418e2ac7efb7f837faa8f61d2574d 
  tzdb-2025a.tar.lz

Here are GPG digital signatures for the release files:

[tz-announce] 2025a release of tz code and data available

Paul Eggert