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2022-08-16Welcome to tzcode-2022cchristos
Work around a bug in onetrueawk that broke commands like 'make traditional_tarballs' on FreeBSD, macOS, etc. (Problem reported by Deborah Goldsmith.) Add code to tzselect that uses experimental structured comments in zone1970.tab to clarify whether Zones like Africa/Abidjan and Europe/Istanbul cross continent or ocean boundaries. (Inspired by a problem reported by Peter Krefting.) Fix bug with 'zic -d /a/b/c' when /a is unwritable but the directory /a/b already exists. Remove zoneinfo2tdf.pl, as it was unused and triggered false malware alarms on some email servers.
2021-10-22Change to code and documentation from 2021a -> 2021echristos
Release 2021e - 2021-10-21 18:41:00 -0700 Changes to code none Release 2021d - 2021-10-15 13:48:18 -0700 Changes to code 'zic -r' now uses "-00" time zone abbreviations for intervals with UT offsets that are unspecified due to -r truncation. This implements a change in draft Internet RFC 8536bis. Release 2021c - 2021-10-01 14:21:49 -0700 Changes to code Fix a bug in 'zic -b fat' that caused old timestamps to be mishandled in 32-bit-only readers (problem reported by Daniel Fischer). Changes to documentation Distribute the SECURITY file (problem reported by Andreas Radke). Release 2021b - 2021-09-24 16:23:00 -0700 Changes to maintenance procedure The new file SECURITY covers how to report security-related bugs. Several backward-compatibility links have been moved to the 'backward' file. These links, which range from Africa/Addis_Ababa to Pacific/Saipan, are only for compatibility with now-obsolete guidelines suggesting an entry for every ISO 3166 code. The intercontinental convenience links Asia/Istanbul and Europe/Nicosia have also been moved to 'backward'. Changes to code zic now creates each output file or link atomically, possibly by creating a temporary file and then renaming it. This avoids races where a TZ setting would temporarily stop working while zic was installing a replacement file or link. zic -L no longer omits the POSIX TZ string in its output. Starting with 2020a, zic -L truncated its output according to the "Expires" directive or "#expires" comment in the leapseconds file. The resulting TZif files omitted daylight saving transitions after the leap second table expired, which led to far less-accurate predictions of times after the expiry. Although future timestamps cannot be converted accurately in the presence of leap seconds, it is more accurate to convert near-future timestamps with a few seconds error than with an hour error, so zic -L no longer truncates output in this way. Instead, when zic -L is given the "Expires" directive, it now outputs the expiration by appending a no-change entry to the leap second table. Although this should work well with most TZif readers, it does not conform to Internet RFC 8536 and some pickier clients (including tzdb 2017c through 2021a) reject it, so "Expires" directives are currently disabled by default. To enable them, set the EXPIRES_LINE Makefile variable. If a TZif file uses this new feature it is marked with a new TZif version number 4, a format intended to be documented in a successor to RFC 8536. zic -L LEAPFILE -r @LO no longer generates an invalid TZif file that omits leap second information for the range LO..B when LO falls between two leap seconds A and B. Instead, it generates a TZif version 4 file that represents the previously-missing information. The TZif reader now allows the leap second table to begin with a correction other than -1 or +1, and to contain adjacent transitions with equal corrections. This supports TZif version 4. The TZif reader now lets leap seconds occur less than 28 days apart. This supports possible future TZif extensions. Fix bug that caused 'localtime' etc. to crash when TZ was set to a all-year DST string like "EST5EDT4,0/0,J365/25" that does not conform to POSIX but does conform to Internet RFC 8536. Fix another bug that caused 'localtime' etc. to crash when TZ was set to a POSIX-conforming but unusual TZ string like "EST5EDT4,0/0,J365/0", where almost all the year is DST. Fix yet another bug that caused 'localtime' etc. to mishandle slim TZif files containing leap seconds after the last explicit transition in the table, or when handling far-future timestamps in slim TZif files lacking leap seconds. Fix localtime misbehavior involving positive leap seconds. This change affects only behavior for "right" system time, which contains leap seconds, and only if the UT offset is not a multiple of 60 seconds when a positive leap second occurs. (No such timezone exists in tzdb, luckily.) Without the fix, the timestamp was ambiguous during a positive leap second. With the fix, any seconds occurring after a positive leap second and within the same localtime minute are counted through 60, not through 59; their UT offset (tm_gmtoff) is the same as before. Here is how the fix affects timestamps in a timezone with UT offset +01:23:45 (5025 seconds) and with a positive leap second at 1972-06-30 23:59:60 UTC (78796800): time_t without the fix with the fix 78796800 1972-07-01 01:23:45 1972-07-01 01:23:45 (leap second) 78796801 1972-07-01 01:23:45 1972-07-01 01:23:46 ... 78796815 1972-07-01 01:23:59 1972-07-01 01:23:60 78796816 1972-07-01 01:24:00 1972-07-01 01:24:00 Fix an unlikely bug that caused 'localtime' etc. to misbehave if civil time changes a few seconds before time_t wraps around, when leap seconds are enabled. Fix bug in zic -r; in some cases, the dummy time type after the last time transition disagreed with the TZ string, contrary to Internet RFC 8563 section 3.3. Fix a bug with 'zic -r @X' when X is a negative leap second that has a nonnegative correction. Without the fix, the output file was truncated so that X appeared to be a positive leap second. Fix a similar, even-less-likely bug when truncating at a positive leap second that has a nonpositive correction. zic -r now reports an error if given rolling leap seconds, as this usage has never generally worked and is evidently unused. zic now generates a POSIX-conforming TZ string for TZif files where all-year DST is predicted for the indefinite future. For example, for all-year Eastern Daylight Time, zic now generates "XXX3EDT4,0/0,J365/23" where it previously generated "EST5EDT,0/0,J365/25" or "". (Thanks to Michael Deckers for noting the possibility of POSIX conformance.) zic.c no longer requires sys/wait.h (thanks to spazmodius for noting it wasn't needed). When reading slim TZif files, zdump no longer mishandles leap seconds on the rare platforms where time_t counts leap seconds, fixing a bug introduced in 2014g. zdump -v now outputs timestamps at boundaries of what localtime and gmtime can represent, instead of the less-useful timestamps one day after the minimum and one day before the maximum. (Thanks to Arthur David Olson for prototype code, and to Manuela Friedrich for debugging help.) zdump's -c and -t options are now consistently inclusive for the lower time bound and exclusive for the upper. Formerly they were inconsistent. (Confusion noted by Martin Burnicki.) Changes to build procedure You can now compile with -DHAVE_MALLOC_ERRNO=0 to port to non-POSIX hosts where malloc doesn't set errno. (Problem reported by Jan Engelhardt.) Changes to documentation tzfile.5 better matches a draft successor to RFC 8536 <https://datatracker.ietf.org/doc/draft-murchison-rfc8536bis/01/>.
2021-03-01Merge tzcode-2021achristos
- No comments in the changelog about the code changes.
2020-10-09Merge tzcode2020b (except we keep tzsetwall(3) for now for compatibility,christos
and we were "slim" already) Support for zic's long-obsolete '-y YEARISTYPE' option has been removed and, with it, so has support for the TYPE field in Rule lines, which is now reserved for compatibility with earlier zic. These features were previously deprecated in release 2015f. (Thanks to Tim Parenti.) zic now defaults to '-b slim' instead of to '-b fat'. zic's new '-l -' and '-p -' options uninstall any existing localtime and posixrules files, respectively. The undocumented and ineffective tzsetwall function has been removed.
2020-05-25Bring in 2020achristos
2019-07-03Sync with 2019b:christos
zic's new -b option supports a way to control data bloat and to test for year-2038 bugs in software that reads TZif files. 'zic -b fat' and 'zic -b slim' generate larger and smaller output; for example, changing from fat to slim shrinks the Europe/London file from 3648 to 1599 bytes, saving about 56%. Fat and slim files represent the same set of timestamps and use the same TZif format as documented in tzfile(5) and in Internet RFC 8536. Fat format attempts to work around bugs or incompatibilities in older software, notably software that mishandles 64-bit TZif data or uses obsolete TZ strings like "EET-2EEST" that lack DST rules. Slim format is more efficient and does not work around 64-bit bugs or obsolete TZ strings. Currently zic defaults to fat format unless you compile with -DZIC_BLOAT_DEFAULT=\"slim\"; this out-of-the-box default is intended to change in future releases as the buggy software often mishandles timestamps anyway. zic no longer treats a set of rules ending in 2037 specially. Previously, zic assumed that such a ruleset meant that future timestamps could not be predicted, and therefore omitted a POSIX-like TZ string in the TZif output. The old behavior is no longer needed for current tzdata, and caused problems with newlib when used with older tzdata (reported by David Gauchard). zic no longer generates some artifact transitions. For example, Europe/London no longer has a no-op transition in January 1996.
2019-04-04merge 2019achristos
Changes to code zic now has an -r option to limit the time range of output data. For example, 'zic -r @1000000000' limits the output data to timestamps starting 1000000000 seconds after the Epoch. This helps shrink output size and can be useful for applications not needing the full timestamp history, such as TZDIST truncation; see Internet RFC 8536 section 5.1. (Inspired by a feature request from Christopher Wong, helped along by bug reports from Wong and from Tim Parenti.) Changes to documentation Mention Internet RFC 8536 (February 2019), which documents TZif. tz-link.html now cites tzdata-meta <https://tzdata-meta.timtimeonline.com/>.
2019-01-01Release 2018i - 2018-12-30 11:05:43 -0800christos
Briefly: São Tomé and Príncipe switches from +01 to +00 on 2019-01-01. Changes to future timestamps Due to a change in government, São Tomé and Príncipe switches back from +01 to +00 on 2019-01-01 at 02:00. (Thanks to Vadim Nasardinov and Michael Deckers.) Release 2018h - 2018-12-23 17:59:32 -0800 Briefly: Qyzylorda, Kazakhstan moved from +06 to +05 on 2018-12-21. New zone Asia/Qostanay because Qostanay, Kazakhstan didn't move. Metlakatla, Alaska observes PST this winter only. Guess Morocco will continue to adjust clocks around Ramadan. Add predictions for Iran from 2038 through 2090. Changes to future timestamps Guess that Morocco will continue to fall back just before and spring forward just after Ramadan, the practice since 2012. (Thanks to Maamar Abdelkader.) This means Morocco will observe negative DST during Ramadan in main and vanguard formats, and in rearguard format it stays in the +00 timezone and observes ordinary DST in all months other than Ramadan. As before, extend this guesswork to the year 2037. As a consequence, Morocco is scheduled to observe three DST transitions in some Gregorian years (e.g., 2033) due to the mismatch between the Gregorian and Islamic calendars. The table of exact transitions for Iranian DST has been extended. It formerly cut off before the year 2038 in a nod to 32-bit time_t. It now cuts off before 2091 as there is doubt about how the Persian calendar will treat 2091. This change predicts DST transitions in 2038-9, 2042-3, and 2046-7 to occur one day later than previously predicted. As before, post-cutoff transitions are approximated. Changes to past and future timestamps Qyzylorda (aka Kyzylorda) oblast in Kazakhstan moved from +06 to +05 on 2018-12-21. This is a zone split as Qostanay (aka Kostanay) did not switch, so create a zone Asia/Qostanay. Metlakatla moved from Alaska to Pacific standard time on 2018-11-04. It did not change clocks that day and remains on -08 this winter. (Thanks to Ryan Stanley.) It will revert to the usual Alaska rules next spring, so this change affects only timestamps from 2018-11-04 through 2019-03-10. Change to past timestamps Kwajalein's 1993-08-20 transition from -12 to +12 was at 24:00, not 00:00. I transcribed the time incorrectly from Shanks. (Thanks to Phake Nick.) Nauru's 1979 transition was on 02-10 at 02:00, not 05-01 at 00:00. (Thanks to Phake Nick.) Guam observed DST irregularly from 1959 through 1977. (Thanks to Phake Nick.) Hong Kong observed DST in 1941 starting 06-15 (not 04-01), then on 10-01 changed standard time to +08:30 (not +08). Its transition back to +08 after WWII was on 1945-09-15, not the previous day. Its 1904-10-30 change took effect at 01:00 +08 (not 00:00 LMT). (Thanks to Phake Nick, Steve Allen, and Joseph Myers.) Also, its 1952 fallback was on 11-02 (not 10-25). This release contains many changes to timestamps before 1946 due to Japanese possession or occupation of Pacific/Chuuk, Pacific/Guam, Pacific/Kosrae, Pacific/Kwajalein, Pacific/Majuro, Pacific/Nauru, Pacific/Palau, and Pacific/Pohnpei. (Thanks to Phake Nick.) Assume that the Spanish East Indies was like the Philippines and observed American time until the end of 1844. This affects Pacific/Chuuk, Pacific/Kosrae, Pacific/Palau, and Pacific/Pohnpei. Changes to past tm_isdst flags For the recent Morocco change, the tm_isdst flag should be 1 from 2018-10-27 00:00 to 2018-10-28 03:00. (Thanks to Michael Deckers.) Give a URL to the official decree. (Thanks to Matt Johnson.)
2018-10-19Update to 2018f:christos
Changes to code zic now always generates TZif files where time type 0 is used for timestamps before the first transition. This simplifies the reading of TZif files and should not affect behavior of existing TZif readers because the same set of time types is used; only their internal indexes may have changed. This affects only the legacy zones EST5EDT, CST6CDT, MST7MDT, PST8PDT, CET, MET, and EET, which previously used nonzero types for these timestamps. Because of the type 0 change, zic no longer outputs a dummy transition at time -2**59 (before the Big Bang), as clients should no longer need this to handle historical timestamps correctly. This reverts a change introduced in 2013d and shrinks most TZif files by a few bytes. zic now supports negative time-of-day in Rule and Leap lines, e.g., "Rule X min max - Apr lastSun -6:00 1:00 -" means the transition occurs at 18:00 on the Saturday before the last Sunday in April. This behavior was documented in 2018a but the code did not entirely match the documentation. localtime.c no longer requires at least one time type in TZif files that lack transitions or have a POSIX-style TZ string. This future-proofs the code against possible future extensions to the format that would allow TZif files with POSIX-style TZ strings and without transitions or time types. A read-access subscript error in localtime.c has been fixed. It could occur only in TZif files with timecnt == 0, something that does not happen in practice now but could happen in future versions. localtime.c no longer ignores TZif POSIX-style TZ strings that specify only standard time. Instead, these TZ strings now override the default time type for timestamps after the last transition (or for all time stamps if there are no transitions), just as DST strings specifying DST have always done. leapseconds.awk now outputs "#updated" and "#expires" comments, and supports leap seconds at the ends of months other than June and December. (Inspired by suggestions from Chris Woodbury.) Changes to documentation New restrictions: A Rule name must start with a character that is neither an ASCII digit nor "-" nor "+", and an unquoted name should not use characters in the set "!$%&'()*,/:;<=>?@[\]^`{|}~". The latter restriction makes room for future extensions (a possibility noted by Tom Lane). tzfile.5 now documents what time types apply before the first and after the last transition, if any. Documentation now uses the spelling "timezone" for a TZ setting that determines timestamp history, and "time zone" for a geographic region currently sharing the same standard time. The name "TZif" is now used for the tz binary data format. tz-link.htm now mentions the A0 TimeZone Migration utilities. (Thanks to Aldrin Martoq for the link.)
2018-05-04Merge 2018echristos
Changes to code zic now accepts subsecond precision in expressions like 00:19:32.13, which is approximately the legal time of the Netherlands from 1835 to 1937. However, because it is questionable whether the few recorded uses of non-integer offsets had subsecond precision in practice, there are no plans for tzdata to use this feature. (Thanks to Steve Allen for pointing out the limitations of historical data in this area.) The code is a bit more portable to MS-Windows. Installers can compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that reserve identifiers like 'localtime'. (Thanks to Manuela Friedrich). Changes to documentation and commentary theory.html now outlines tzdb's extensions to POSIX's model for civil time, and has a section "POSIX features no longer needed" that lists POSIX API components that are now vestigial. (From suggestions by Steve Summit.) It also better distinguishes time zones from tz regions. (From a suggestion by Guy Harris.) Commentary is now more consistent about using the phrase "daylight saving time", to match the C name tm_isdst. Daylight saving time need not occur in summer, and need not have a positive offset from standard time. Commentary about historical transitions in Uruguay has been expanded with links to many relevant legal documents. (Thanks to Tim Parenti.) Commentary now uses some non-ASCII characters with Unicode value less than U+0100, as they can be useful and should work even with older editors such as XEmacs.