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tzid in zoneinfo?
by Steven R. Loomis Feb. 13, 2017

Feb. 13, 2017

Dear TZ list, I would like to propose that zic-compiled binaries (such as what shows up in /etc/zoneinfo) include the tzid (such as ‘America/New_York’). I work on the ICU project (Unicode’s International Components for Unicode) and also CLDR (Unicode’s Common Locale Data Repository). The ICU library consumes tz data, and uses the localized data from CLDR to (among other things) display translated time zone names of various sorts, and format different types of dates. A perpetual problem is trying to detect the actual timezone of a platform. Ideally something like the TZ variable is set to a valid tz id such as America/New_York which we can use directly. Otherwise, we try various approaches - including trying to resolve /etc/localtime’s symlink to see if it points to a file which appears to be in some sort of zic-compiled tree. This brings up bugs such as http://bugs.icu-project.org/trac/ticket/12770 because various platforms use different paths as the targets of /etc/localtime - and some times, it's a doubly linked symlink. In other cases, the file is just copied, and we have to trawl through /usr/share/zoneinfo looking for a binary file which matches. There are other methods employed if these fail, but I think this will suffice for our purposes. Even if ICU consumed the /etc/zoneinfo file directly, or was able to call the host to perform the calculations it needs, that would not suffice in terms of localized content. As I think has been noted on this list before, it does not seem to be a goal of the tz database to collect these translated names, and tz-link.html does link to CLDR as one possible source of translations. I think that this would benefit other users as well, by making zone files self identifiable. I think the JDK has to do similar analysis. Some JavaScript containers (Mozilla especially) now support IANA tz ids, such as in https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Ob… Any thoughts or comments? Thanks, Steven

5 5

Re: [tz] Version in zoneinfo files?
by Guy Harris Feb. 10, 2017

Feb. 10, 2017

On Oct 25, 2015, at 10:55 AM, Paul G <paul(a)ganssle.io> wrote: > I'm not suggesting that it be impossible to create a weird result when asking for the version, just that there's a standard place for the version to go, and preferably the standard default gives you something that you expected. I.e., something that works most of the time is sufficient? So what exactly is the intended use of this version field? > As it is now, you're virtually guaranteed to have a lot of incompatibility because there's nothing you can point to that says, "This is the canonical way to store version information about zoneinfo files", and no standard has emerged on how to do this as is. > > On 10/25/2015 01:51 PM, Guy Harris wrote: >> >> On Oct 25, 2015, at 10:37 AM, Paul G <paul(a)ganssle.io> wrote: >> >>> On 10/25/2015 01:35 PM, Guy Harris wrote: >>> >>>> So where would zic get the version information to put into the binary files? >>> >>> My understanding is that it's the VERSION= line of the Makefile in the tzdata tarballs. >> >> I.e., you're proposing that the value of the VERSION value in the Makefile be passed as an argument to zic, and zic would put the value of that argument into a field in the files? >> >> So, if the goal is to provide a "reliable way to get the version information in a cross-platform way", what would ensure that this field be set properly, for some value of "properly", everywhere that binary tzdata files are generated? >> >> I.e., what is to guarantee that >> >> 1) nobody downstream change VERSION if they aren't changing the zic files from what's distributed >> >> and >> >> 2) people change it "properly" if the files don't correspond to a particular version of files that were distributed (e.g., if some downstream supplier takes 2015q and adds some changes mentioned on the list to it before 2015r comes out with those changes plus other changes, they should call the resulting files something other than "2015q" or "2015r")? >> >

20 55

Re: [tz] Help needed on Tz database
by Bill Seymour Feb. 2, 2017

Feb. 2, 2017

Hi, François, I'm surprised that that old paper is still around. I wrote it mainly for my own benefit when I was trying to understand the tz source files. The way I read the C-EUR rules is that there was a switch to summer time in 1940, but no change back until 1942; so when Minsk changed to C-EUR, the steady state implied by the most recent C-EUR transition would be UTC+1:00; and so the wall clock time in Minsk would be UTC+2:00 and the abbreviation would be CEST. But I'm just an amateur at civil time. I'm including the tz mailing list in this message's recipients in case somebody who really knows will correct me if I'm wrong. 8-) --Bill On Thu, Feb 2, 2017 at 1:25 AM, Francois Rouleau <rouf0007(a)gmail.com> wrote: > Hi > I read "How to read the Tz Database" but there is a case (maybe more later) > that I dont understand. From https://www.timeanddate.com, for Minsk, I see > that: > > "Saturday, June 28, 1941, 12:00:00 midnight clocks were > turned backward 1 hour to Friday, June 27, 1941, 11:00:00 pm local > daylight time instead" > > > > Zone: > ===== > > # Zone NAME GMTOFF RULES FORMAT [UNTIL] > Zone Europe/Minsk 1:50:16 - LMT 1880 > 1:50 - MMT 1924 May 2 # Minsk Mean Time > 2:00 - EET 1930 Jun 21 > 3:00 - MSK 1941 Jun 28 > 1:00 C-Eur CE%sT 1944 Jul 3 > 3:00 Russia MSK/MSD 1990 > 3:00 - MSK 1991 Mar 31 2:00s > 2:00 Russia EE%sT 2011 Mar 27 2:00s > 3:00 - +03 > > Rules: > > RuleName From To Month Day Start Add S/D > Rule C-Eur 1917 1918 - Sep Mon>=15 2:00s 0 - > Rule C-Eur 1940 only - Apr 1 2:00s 1:00 S > Rule C-Eur 1942 only - Nov 2 2:00s 0 - > Rule C-Eur 1943 only - Mar 29 2:00s 1:00 S > Rule C-Eur 1943 only - Oct 4 2:00s 0 - > Rule C-Eur 1944 1945 - Apr Mon>=1 2:00s 1:00 S > Rule C-Eur 1944 only - Oct 2 2:00s 0 - > > > Question: > > On June 28, 1941, the C-Eur rule takes over. What row of the rule section > should I look at? > > Is it the letter column (in rule) that will tell me if this new time is STD > or DST ? > > > Thanks > > François >

3 2

Magallanes region from Chile will keep DST all year round
by Juan Correa Jan. 30, 2017

Jan. 30, 2017

There is no official decree published yet, but it has been reported by official Chilean government Twitter accounts that Magallanes región ( https://en.wikipedia.org/wiki/Magallanes_Region) will keep DST (UTC -3) all year round Sources: - https://twitter.com/presidencia_cl/status/805398903604576256 (from Press Office of the Presidency of Chile, "President Michelle Bachelet signs the decree that establishes a single timezone for Magallanes región") - https://twitter.com/AndresReboll/status/805398964690386944 (from Minister of Energy, "after a participative (sic) process and thoughtful investigation, decided to establish a single timezone (*summer*) for Magallanes) - http://www.soychile.cl/Santiago/Sociedad/2016/12/04/433428/Bachelet-firmo-e… As a reminder, Chile has (since 2016) DST from August to May following year The biggest city in the region is Punta Arenas, with over 123 thousand inhabitants. The whole population for Magallanes region is 164.661 people As soon as the decree gets published, I'll share it here -- Juan Correa Poblete PS Labs (http://www.pslabs.cl)

10 25

[PROPOSED] Remove many invented abbreviations in 'asia'
by Paul Eggert Jan. 20, 2017

Jan. 20, 2017

* NEWS: Document this. List areas changed rather than each individual zone, as there are so many. * asia (Asia/Kabul, Asia/Dhaka, Asia/Thimphu, Indian/Chagos) (Asia/Brunei, Asia/Yangon, Asia/Urumqi, Asia/Taipei, Asia/Dili) (Asia/Kolkata, Asia/Jakarta, Asia/Pontianak, Asia/Makassar) (Asia/Jayapura, Asia/Tehran, Asia/Baghdad, Asia/Kuala_Lumpur) (Asia/Kuching, Indian/Maldives, Asia/Hovd, Asia/Ulaanbaatar) (Asia/Choibalsan, Asia/Kathmandu, Asia/Karachi, Asia/Manila, Asia/Qatar) (Asia/Riyadh, Asia/Singapore, Asia/Bangkok, Asia/Dubai) (Asia/Ho_Chi_Minh): Use numeric rather than invented abbreviations. (Asia/Taipei, Macau, Asia/Macau, Asia/Tokyo, Asia/Seoul, Asia/Pyongyang): Use common (e.g., "JST") rather than invented (e.g., "JCST") abbreviations. (Asia/Colombo): Remove unused abbreviations. --- NEWS | 39 ++++------ asia | 258 +++++++++++++++++++++++++++++++------------------------------------ 2 files changed, 136 insertions(+), 161 deletions(-) diff --git a/NEWS b/NEWS index 79620eb..8276cc7 100644 --- a/NEWS +++ b/NEWS @@ -32,36 +32,27 @@ Unreleased, experimental changes Switch to numeric time zone abbreviations for South America, as part of the ongoing project of removing invented abbreviations. This avoids the need to invent an abbreviation for the new Chilean - new zone. This change affects America/Araguaina, - America/Argentina/Buenos_Aires, America/Argentina/Catamarca, - America/Argentina/Cordoba, America/Argentina/Jujuy, - America/Argentina/La_Rioja, America/Argentina/Mendoza, - America/Argentina/Rio_Gallegos, America/Argentina/Salta, - America/Argentina/San_Juan, America/Argentina/San_Luis, - America/Argentina/Tucuman, America/Argentina/Ushuaia, - America/Asuncion, America/Bahia, America/Belem, America/Boa_Vista, - America/Bogota, America/Campo_Grande, America/Caracas, - America/Cayenne, America/Cuiaba, America/Curacao, - America/Eirunepe, America/Fortaleza, America/Guayaquil, - America/Guyana, America/La_Paz, America/Lima, America/Maceio, - America/Manaus, America/Montevideo, America/Noronha, - America/Paramaribo, America/Porto_Velho, America/Recife, - America/Rio_Branco, America/Santarem, America/Santiago, - America/Sao_Paulo, Antarctica/Palmer, Atlantic/South_Georgia, - Atlantic/Stanley, Pacific/Easter, and Pacific/Galapagos. - - Similarly, switch from invented to numeric time zone abbreviations - for Greenland, the Azores, and St Pierre and Miquelon; for - half-hour DST in Belize before 1944 and in the Dominican Republic - before 1975; and for Canary Islands before 1946, for Madeira - before 1967, for Iceland before 1969, for the Netherlands in - 1937-9, and for Zaporozhye in 1880-1924. + new zone. Similarly, switch from invented to numeric time zone + abbreviations for Afghanistan, the Azores, Bangladesh, Bhutan, the + British Indian Ocean Territory, Brunei, Dubai, East Timor, + Greenland, Indochina, Iran, Iraq, Malaysia, the Maldives, + Mongolia, Myanmar, Nepal, the Philippines, Qatar, St Pierre and + Miquelon, Saudi Arabia, Singapore, and Xinjiang; for half-hour DST + in Belize before 1944 and in the Dominican Republic before 1975; + and for Canary Islands before 1946, for Madeira before 1967, for + Iceland before 1969, for Indian Summer Time before 1942, for + Indonesia before around 1964, for the Netherlands in 1937-9, for + Pakistan before 1971, and for Zaporozhye in 1880-1924. For Alaska time from 1900 through 1967, instead of "CAT" use the abbreviation "AST", the abbreviation commonly used at the time (Atlantic Standard Time had not been standardized yet). Use "AWT" and "APT" instead of the invented abbreviations "CAWT" and "CAPT". + Use "CST" and "CDT" instead of invented abbreviations for Macau + before 1999 and Taiwan before 1938, and use "JST" instead of the + invented abbreviation "JCST" for Japan and Korea before 1938. + Changes to code zic no longer mishandles some transitions in January 2038 when it diff --git a/asia b/asia index 6129614..26b6a5b 100644 --- a/asia +++ b/asia @@ -6,15 +6,15 @@ # tz(a)iana.org for general use in the future). For more, please see # the file CONTRIBUTING in the tz distribution. -# From Paul Eggert (2015-08-08): +# From Paul Eggert (2017-01-13): # # Unless otherwise specified, the source for data through 1990 is: # Thomas G. Shanks and Rique Pottenger, The International Atlas (6th edition), # San Diego: ACS Publications, Inc. (2003). # Unfortunately this book contains many errors and cites no sources. # -# Gwillim Law writes that a good source -# for recent time zone data is the International Air Transport +# Many years ago Gwillim Law wrote that a good source +# for time zone data was the International Air Transport # Association's Standard Schedules Information Manual (IATA SSIM), # published semiannually. Law sent in several helpful summaries # of the IATA's data after 1990. Except where otherwise noted, @@ -35,29 +35,24 @@ # A reliable and entertaining source about time zones is # Derek Howse, Greenwich time and longitude, Philip Wilson Publishers (1997). # -# I invented the abbreviations marked '*' in the following table; -# the rest are from earlier versions of this file, or from other sources. -# Corrections are welcome! +# The following alphabetic abbreviations appear in these tables: # std dst # LMT Local Mean Time # 2:00 EET EEST Eastern European Time # 2:00 IST IDT Israel -# 3:00 AST ADT Arabia* -# 3:30 IRST IRDT Iran* -# 4:00 GST Gulf* # 5:30 IST India -# 7:00 ICT Indochina, most times and locations* # 7:00 WIB west Indonesia (Waktu Indonesia Barat) # 8:00 WITA central Indonesia (Waktu Indonesia Tengah) # 8:00 CST China -# 8:00 IDT Indochina, 1943-45, 1947-55, 1960-75 (some locations)* -# 8:00 JWST Western Standard Time (Japan, 1896/1937)* -# 8:30 KST KDT Korea when at +0830* -# 9:00 JCST Central Standard Time (Japan, 1896/1937) +# 8:30 KST KDT Korea when at +0830 # 9:00 WIT east Indonesia (Waktu Indonesia Timur) # 9:00 JST JDT Japan # 9:00 KST KDT Korea when at +09 # 9:30 ACST Australian Central Standard Time +# Otherwise, these tables typically use numeric abbreviations like +03 +# and +0330 for integer hour and minute UTC offsets. Although earlier +# editions invented alphabetic time zone abbreviations for every +# offset, this did not reflect common practice. # # See the 'europe' file for Russia and Turkey in Asia. @@ -65,7 +60,7 @@ # Incorporates data for Singapore from Robert Elz' asia 1.1, as well as # additional information from Tom Yap, Sun Microsystems Intercontinental # Technical Support (including a page from the Official Airline Guide - -# Worldwide Edition). The names for time zones are guesses. +# Worldwide Edition). ############################################################################### @@ -86,8 +81,8 @@ Rule RussiaAsia 1996 2011 - Oct lastSun 2:00s 0 - # Afghanistan # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Kabul 4:36:48 - LMT 1890 - 4:00 - AFT 1945 - 4:30 - AFT + 4:00 - +04 1945 + 4:30 - +0430 # Armenia # From Paul Eggert (2006-03-22): @@ -230,18 +225,17 @@ Rule Dhaka 2009 only - Dec 31 24:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Dhaka 6:01:40 - LMT 1890 5:53:20 - HMT 1941 Oct # Howrah Mean Time? - 6:30 - BURT 1942 May 15 # Burma Time - 5:30 - IST 1942 Sep - 6:30 - BURT 1951 Sep 30 - 6:00 - DACT 1971 Mar 26 # Dacca Time - 6:00 - BDT 2009 - 6:00 Dhaka BD%sT + 6:30 - +0630 1942 May 15 + 5:30 - +0530 1942 Sep + 6:30 - +0630 1951 Sep 30 + 6:00 - +06 2009 + 6:00 Dhaka +06/+07 # Bhutan # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Thimphu 5:58:36 - LMT 1947 Aug 15 # or Thimbu - 5:30 - IST 1987 Oct - 6:00 - BTT # Bhutan Time + 5:30 - +0530 1987 Oct + 6:00 - +06 # British Indian Ocean Territory # Whitman and the 1995 CIA time zone map say 5:00, but the @@ -251,14 +245,14 @@ Zone Asia/Thimphu 5:58:36 - LMT 1947 Aug 15 # or Thimbu # then contained the Chagos Archipelago). # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Indian/Chagos 4:49:40 - LMT 1907 - 5:00 - IOT 1996 # BIOT Time - 6:00 - IOT + 5:00 - +05 1996 + 6:00 - +06 # Brunei # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Brunei 7:39:40 - LMT 1926 Mar # Bandar Seri Begawan - 7:30 - BNT 1933 - 8:00 - BNT + 7:30 - +0730 1933 + 8:00 - +08 # Burma / Myanmar @@ -267,9 +261,9 @@ Zone Asia/Brunei 7:39:40 - LMT 1926 Mar # Bandar Seri Begawan # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Yangon 6:24:40 - LMT 1880 # or Rangoon 6:24:40 - RMT 1920 # Rangoon Mean Time? - 6:30 - BURT 1942 May # Burma Time - 9:00 - JST 1945 May 3 - 6:30 - MMT # Myanmar Time + 6:30 - +0630 1942 May + 9:00 - +09 1945 May 3 + 6:30 - +0630 # Cambodia # See Asia/Bangkok. @@ -521,7 +515,7 @@ Zone Asia/Shanghai 8:05:43 - LMT 1901 # Xinjiang time, used by many in western China; represented by Ürümqi / Ürümchi # / Wulumuqi. (Please use Asia/Shanghai if you prefer Beijing time.) Zone Asia/Urumqi 5:50:20 - LMT 1928 - 6:00 - XJT + 6:00 - +06 # Hong Kong (Xianggang) @@ -740,30 +734,29 @@ Rule Taiwan 1979 only - Oct 1 0:00 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] # Taipei or Taibei or T'ai-pei Zone Asia/Taipei 8:06:00 - LMT 1896 Jan 1 - 8:00 - JWST 1937 Oct 1 + 8:00 - CST 1937 Oct 1 9:00 - JST 1945 Sep 21 1:00 8:00 Taiwan C%sT # Macau (Macao, Aomen) # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S -Rule Macau 1961 1962 - Mar Sun>=16 3:30 1:00 S -Rule Macau 1961 1964 - Nov Sun>=1 3:30 0 - -Rule Macau 1963 only - Mar Sun>=16 0:00 1:00 S -Rule Macau 1964 only - Mar Sun>=16 3:30 1:00 S -Rule Macau 1965 only - Mar Sun>=16 0:00 1:00 S -Rule Macau 1965 only - Oct 31 0:00 0 - -Rule Macau 1966 1971 - Apr Sun>=16 3:30 1:00 S -Rule Macau 1966 1971 - Oct Sun>=16 3:30 0 - -Rule Macau 1972 1974 - Apr Sun>=15 0:00 1:00 S -Rule Macau 1972 1973 - Oct Sun>=15 0:00 0 - -Rule Macau 1974 1977 - Oct Sun>=15 3:30 0 - -Rule Macau 1975 1977 - Apr Sun>=15 3:30 1:00 S -Rule Macau 1978 1980 - Apr Sun>=15 0:00 1:00 S -Rule Macau 1978 1980 - Oct Sun>=15 0:00 0 - +Rule Macau 1961 1962 - Mar Sun>=16 3:30 1:00 D +Rule Macau 1961 1964 - Nov Sun>=1 3:30 0 S +Rule Macau 1963 only - Mar Sun>=16 0:00 1:00 D +Rule Macau 1964 only - Mar Sun>=16 3:30 1:00 D +Rule Macau 1965 only - Mar Sun>=16 0:00 1:00 D +Rule Macau 1965 only - Oct 31 0:00 0 S +Rule Macau 1966 1971 - Apr Sun>=16 3:30 1:00 D +Rule Macau 1966 1971 - Oct Sun>=16 3:30 0 S +Rule Macau 1972 1974 - Apr Sun>=15 0:00 1:00 D +Rule Macau 1972 1973 - Oct Sun>=15 0:00 0 S +Rule Macau 1974 1977 - Oct Sun>=15 3:30 0 S +Rule Macau 1975 1977 - Apr Sun>=15 3:30 1:00 D +Rule Macau 1978 1980 - Apr Sun>=15 0:00 1:00 D +Rule Macau 1978 1980 - Oct Sun>=15 0:00 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Macau 7:34:20 - LMT 1912 Jan 1 - 8:00 Macau MO%sT 1999 Dec 20 # return to China - 8:00 PRC C%sT + 8:00 Macau C%sT ############################################################################### @@ -879,11 +872,10 @@ Zone Asia/Tbilisi 2:59:11 - LMT 1880 # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Dili 8:22:20 - LMT 1912 Jan 1 - 8:00 - TLT 1942 Feb 21 23:00 # E Timor Time - 9:00 - JST 1945 Sep 23 - 9:00 - TLT 1976 May 3 - 8:00 - WITA 2000 Sep 17 0:00 - 9:00 - TLT + 8:00 - +08 1942 Feb 21 23:00 + 9:00 - +09 1976 May 3 + 8:00 - +08 2000 Sep 17 0:00 + 9:00 - +09 # India @@ -898,9 +890,9 @@ Zone Asia/Dili 8:22:20 - LMT 1912 Jan 1 # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Kolkata 5:53:28 - LMT 1880 # Kolkata 5:53:20 - HMT 1941 Oct # Howrah Mean Time? - 6:30 - BURT 1942 May 15 # Burma Time + 6:30 - +0630 1942 May 15 5:30 - IST 1942 Sep - 5:30 1:00 IST 1945 Oct 15 + 5:30 1:00 +0630 1945 Oct 15 5:30 - IST # The following are like Asia/Kolkata: # Andaman Is @@ -951,33 +943,33 @@ Zone Asia/Jakarta 7:07:12 - LMT 1867 Aug 10 # Shanks & Pottenger say the next transition was at 1924 Jan 1 0:13, # but this must be a typo. 7:07:12 - BMT 1923 Dec 31 23:47:12 # Batavia - 7:20 - JAVT 1932 Nov # Java Time - 7:30 - WIB 1942 Mar 23 - 9:00 - JST 1945 Sep 23 - 7:30 - WIB 1948 May - 8:00 - WIB 1950 May - 7:30 - WIB 1964 + 7:20 - +0720 1932 Nov + 7:30 - +0730 1942 Mar 23 + 9:00 - +09 1945 Sep 23 + 7:30 - +0730 1948 May + 8:00 - +08 1950 May + 7:30 - +0730 1964 7:00 - WIB # west and central Borneo Zone Asia/Pontianak 7:17:20 - LMT 1908 May 7:17:20 - PMT 1932 Nov # Pontianak MT - 7:30 - WIB 1942 Jan 29 - 9:00 - JST 1945 Sep 23 - 7:30 - WIB 1948 May - 8:00 - WIB 1950 May - 7:30 - WIB 1964 + 7:30 - +0730 1942 Jan 29 + 9:00 - +09 1945 Sep 23 + 7:30 - +0730 1948 May + 8:00 - +08 1950 May + 7:30 - +0730 1964 8:00 - WITA 1988 Jan 1 7:00 - WIB # Sulawesi, Lesser Sundas, east and south Borneo Zone Asia/Makassar 7:57:36 - LMT 1920 7:57:36 - MMT 1932 Nov # Macassar MT - 8:00 - WITA 1942 Feb 9 - 9:00 - JST 1945 Sep 23 + 8:00 - +08 1942 Feb 9 + 9:00 - +09 1945 Sep 23 8:00 - WITA # Maluku Islands, West Papua, Papua Zone Asia/Jayapura 9:22:48 - LMT 1932 Nov - 9:00 - WIT 1944 Sep 1 - 9:30 - ACST 1964 + 9:00 - +09 1944 Sep 1 + 9:30 - +0930 1964 9:00 - WIT # Iran @@ -1009,8 +1001,6 @@ Zone Asia/Jayapura 9:22:48 - LMT 1932 Nov # for at least the last 5 years. Before that, for a few years, the # date used was the first Thursday night of Farvardin and the last # Thursday night of Shahrivar, but I can't give exact dates.... -# I have also changed the abbreviations to what is considered correct -# here in Iran, IRST for regular time and IRDT for daylight saving time. # # From Roozbeh Pournader (2005-04-05): # The text of the Iranian law, in effect since 1925, clearly mentions @@ -1117,9 +1107,9 @@ Rule Iran 2036 max - Sep 21 0:00 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Tehran 3:25:44 - LMT 1916 3:25:44 - TMT 1946 # Tehran Mean Time - 3:30 - IRST 1977 Nov - 4:00 Iran IR%sT 1979 - 3:30 Iran IR%sT + 3:30 - +0330 1977 Nov + 4:00 Iran +04/+05 1979 + 3:30 Iran +0330/+0430 # Iraq @@ -1162,8 +1152,8 @@ Rule Iraq 1991 2007 - Oct 1 3:00s 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Baghdad 2:57:40 - LMT 1890 2:57:36 - BMT 1918 # Baghdad Mean Time? - 3:00 - AST 1982 May - 3:00 Iraq A%sT + 3:00 - +03 1982 May + 3:00 Iraq +03/+04 ############################################################################### @@ -1462,8 +1452,6 @@ Rule Japan 1950 1951 - May Sun>=1 2:00 1:00 D # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Tokyo 9:18:59 - LMT 1887 Dec 31 15:00u - 9:00 - JST 1896 Jan 1 - 9:00 - JCST 1937 Oct 1 9:00 Japan J%sT # Since 1938, all Japanese possessions have been like Asia/Tokyo. @@ -1940,14 +1928,12 @@ Rule ROK 1987 1988 - Oct Sun>=8 3:00 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Seoul 8:27:52 - LMT 1908 Apr 1 8:30 - KST 1912 Jan 1 - 9:00 - JCST 1937 Oct 1 9:00 - JST 1945 Sep 8 9:00 - KST 1954 Mar 21 8:30 ROK K%sT 1961 Aug 10 9:00 ROK K%sT Zone Asia/Pyongyang 8:23:00 - LMT 1908 Apr 1 8:30 - KST 1912 Jan 1 - 9:00 - JCST 1937 Oct 1 9:00 - JST 1945 Aug 24 9:00 - KST 2015 Aug 15 00:00 8:30 - KST @@ -2002,30 +1988,29 @@ Rule NBorneo 1935 1941 - Dec 14 0:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Kuala_Lumpur 6:46:46 - LMT 1901 Jan 1 6:55:25 - SMT 1905 Jun 1 # Singapore M.T. - 7:00 - MALT 1933 Jan 1 # Malaya Time - 7:00 0:20 MALST 1936 Jan 1 - 7:20 - MALT 1941 Sep 1 - 7:30 - MALT 1942 Feb 16 - 9:00 - JST 1945 Sep 12 - 7:30 - MALT 1982 Jan 1 - 8:00 - MYT # Malaysia Time + 7:00 - +07 1933 Jan 1 + 7:00 0:20 +0720 1936 Jan 1 + 7:20 - +0720 1941 Sep 1 + 7:30 - +0730 1942 Feb 16 + 9:00 - +09 1945 Sep 12 + 7:30 - +0730 1982 Jan 1 + 8:00 - +08 # Sabah & Sarawak # From Paul Eggert (2014-08-12): # The data entries here are mostly from Shanks & Pottenger, but the 1942, 1945 # and 1982 transition dates are from Mok Ly Yng. # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Kuching 7:21:20 - LMT 1926 Mar - 7:30 - BORT 1933 # Borneo Time - 8:00 NBorneo BOR%sT 1942 Feb 16 - 9:00 - JST 1945 Sep 12 - 8:00 - BORT 1982 Jan 1 - 8:00 - MYT + 7:30 - +0730 1933 + 8:00 NBorneo +08/+0820 1942 Feb 16 + 9:00 - +09 1945 Sep 12 + 8:00 - +08 # Maldives # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Indian/Maldives 4:54:00 - LMT 1880 # Male 4:54:00 - MMT 1960 # Male Mean Time - 5:00 - MVT # Maldives Time + 5:00 - +05 # Mongolia @@ -2164,25 +2149,25 @@ Rule Mongol 2015 max - Sep lastSat 0:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] # Hovd, a.k.a. Chovd, Dund-Us, Dzhargalant, Khovd, Jirgalanta Zone Asia/Hovd 6:06:36 - LMT 1905 Aug - 6:00 - HOVT 1978 # Hovd Time - 7:00 Mongol HOV%sT + 6:00 - +06 1978 + 7:00 Mongol +07/+08 # Ulaanbaatar, a.k.a. Ulan Bataar, Ulan Bator, Urga Zone Asia/Ulaanbaatar 7:07:32 - LMT 1905 Aug - 7:00 - ULAT 1978 # Ulaanbaatar Time - 8:00 Mongol ULA%sT + 7:00 - +07 1978 + 8:00 Mongol +08/+09 # Choibalsan, a.k.a. Bajan Tümen, Bajan Tumen, Chojbalsan, # Choybalsan, Sanbejse, Tchoibalsan Zone Asia/Choibalsan 7:38:00 - LMT 1905 Aug - 7:00 - ULAT 1978 - 8:00 - ULAT 1983 Apr - 9:00 Mongol CHO%sT 2008 Mar 31 # Choibalsan Time - 8:00 Mongol CHO%sT + 7:00 - +07 1978 + 8:00 - +08 1983 Apr + 9:00 Mongol +09/+10 2008 Mar 31 + 8:00 Mongol +08/+09 # Nepal # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Kathmandu 5:41:16 - LMT 1920 - 5:30 - IST 1986 - 5:45 - NPT # Nepal Time + 5:30 - +0530 1986 + 5:45 - +0545 # Oman # See Asia/Dubai. @@ -2331,10 +2316,10 @@ Rule Pakistan 2009 only - Apr 15 0:00 1:00 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Karachi 4:28:12 - LMT 1907 - 5:30 - IST 1942 Sep - 5:30 1:00 IST 1945 Oct 15 - 5:30 - IST 1951 Sep 30 - 5:00 - KART 1971 Mar 26 # Karachi Time + 5:30 - +0530 1942 Sep + 5:30 1:00 +0630 1945 Oct 15 + 5:30 - +0530 1951 Sep 30 + 5:00 - +05 1971 Mar 26 5:00 Pakistan PK%sT # Pakistan Time # Palestine @@ -2699,15 +2684,15 @@ Rule Phil 1978 only - Sep 21 0:00 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Manila -15:56:00 - LMT 1844 Dec 31 8:04:00 - LMT 1899 May 11 - 8:00 Phil PH%sT 1942 May - 9:00 - JST 1944 Nov - 8:00 Phil PH%sT + 8:00 Phil +08/+09 1942 May + 9:00 - +09 1944 Nov + 8:00 Phil +08/+09 # Qatar # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Qatar 3:26:08 - LMT 1920 # Al Dawhah / Doha - 4:00 - GST 1972 Jun - 3:00 - AST + 4:00 - +04 1972 Jun + 3:00 - +03 Link Asia/Qatar Asia/Bahrain # Saudi Arabia @@ -2734,7 +2719,7 @@ Link Asia/Qatar Asia/Bahrain # # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Riyadh 3:06:52 - LMT 1947 Mar 14 - 3:00 - AST + 3:00 - +03 Link Asia/Riyadh Asia/Aden # Yemen Link Asia/Riyadh Asia/Kuwait @@ -2744,14 +2729,13 @@ Link Asia/Riyadh Asia/Kuwait # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Singapore 6:55:25 - LMT 1901 Jan 1 6:55:25 - SMT 1905 Jun 1 # Singapore M.T. - 7:00 - MALT 1933 Jan 1 # Malaya Time - 7:00 0:20 MALST 1936 Jan 1 - 7:20 - MALT 1941 Sep 1 - 7:30 - MALT 1942 Feb 16 - 9:00 - JST 1945 Sep 12 - 7:30 - MALT 1965 Aug 9 # independence - 7:30 - SGT 1982 Jan 1 # Singapore Time - 8:00 - SGT + 7:00 - +07 1933 Jan 1 + 7:00 0:20 +0720 1936 Jan 1 + 7:20 - +0720 1941 Sep 1 + 7:30 - +0730 1942 Feb 16 + 9:00 - +09 1945 Sep 12 + 7:30 - +0730 1982 Jan 1 + 8:00 - +08 # Spratly Is # no information @@ -2810,8 +2794,8 @@ Zone Asia/Singapore 6:55:25 - LMT 1901 Jan 1 Zone Asia/Colombo 5:19:24 - LMT 1880 5:19:32 - MMT 1906 # Moratuwa Mean Time 5:30 - +0530 1942 Jan 5 - 5:30 0:30 +0530/+06 1942 Sep - 5:30 1:00 +0530/+0630 1945 Oct 16 2:00 + 5:30 0:30 +06 1942 Sep + 5:30 1:00 +0630 1945 Oct 16 2:00 5:30 - +0530 1996 May 25 0:00 6:30 - +0630 1996 Oct 26 0:30 6:00 - +06 2006 Apr 15 0:30 @@ -2993,7 +2977,7 @@ Zone Asia/Dushanbe 4:35:12 - LMT 1924 May 2 # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Bangkok 6:42:04 - LMT 1880 6:42:04 - BMT 1920 Apr # Bangkok Mean Time - 7:00 - ICT + 7:00 - +07 Link Asia/Bangkok Asia/Phnom_Penh # Cambodia Link Asia/Bangkok Asia/Vientiane # Laos @@ -3009,7 +2993,7 @@ Zone Asia/Ashgabat 3:53:32 - LMT 1924 May 2 # or Ashkhabad # United Arab Emirates # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Dubai 3:41:12 - LMT 1920 - 4:00 - GST + 4:00 - +04 Link Asia/Dubai Asia/Muscat # Oman # Uzbekistan @@ -3082,15 +3066,15 @@ Zone Asia/Tashkent 4:37:11 - LMT 1924 May 2 # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Ho_Chi_Minh 7:06:40 - LMT 1906 Jul 1 - 7:06:30 - PLMT 1911 May 1 - 7:00 - ICT 1942 Dec 31 23:00 - 8:00 - IDT 1945 Mar 14 23:00 - 9:00 - JST 1945 Sep 2 - 7:00 - ICT 1947 Apr 1 - 8:00 - IDT 1955 Jul 1 - 7:00 - ICT 1959 Dec 31 23:00 - 8:00 - IDT 1975 Jun 13 - 7:00 - ICT + 7:06:30 - PLMT 1911 May 1 # Phù Liễn MT + 7:00 - +07 1942 Dec 31 23:00 + 8:00 - +08 1945 Mar 14 23:00 + 9:00 - +09 1945 Sep 2 + 7:00 - +07 1947 Apr 1 + 8:00 - +08 1955 Jul 1 + 7:00 - +07 1959 Dec 31 23:00 + 8:00 - +08 1975 Jun 13 + 7:00 - +07 # Yemen # See Asia/Riyadh. -- 2.9.3

5 7

[PROPOSED] date +%z now outputs -0000 for uninhabited
by Paul Eggert Jan. 16, 2017

Jan. 16, 2017

When the time zone has UT offset 0 and the time zone abbreviation begins with "-", the %z spec now expands to -0000 instead of to +0000. This conveys more-useful info, and is what the next version of GNU 'date' is intended to do. * NEWS, newstrftime.3: Document change. * date.1: Document %z. * strftime.c (_fmt): Implement change. --- NEWS | 4 ++++ date.1 | 1 + newstrftime.3 | 12 ++++++++++++ strftime.c | 13 ++++++++++++- 4 files changed, 29 insertions(+), 1 deletion(-) diff --git a/NEWS b/NEWS index 8276cc7..3975295 100644 --- a/NEWS +++ b/NEWS @@ -74,6 +74,10 @@ Unreleased, experimental changes when TZ is set to a POSIX-style string that specifies DST. (Problem reported by Kees Dekker.) + date and strftime now cause %z to generate "-0000" instead of + "+0000" when the UT offset is zero and the time zone abbreviation + begins with "-". + Changes to documentation and commentary tz-link.htm now covers leap smearing, which is popular in clouds. diff --git a/date.1 b/date.1 index 7fd4848..579ab92 100644 --- a/date.1 +++ b/date.1 @@ -90,6 +90,7 @@ to be output in a particular way %X 14:54:40 Time* %y 89 Last two digits of year %Y 1989 Year in full +%z -0500 Numeric time zone %Z EST Time zone abbreviation %+ Wed Mar 8 14:54:40 EST 1989 Default output format* .if t .in -.5i diff --git a/newstrftime.3 b/newstrftime.3 index 9a60ee3..8f1be34 100644 --- a/newstrftime.3 +++ b/newstrftime.3 @@ -50,6 +50,13 @@ strftime \- format date and time .SH DESCRIPTION .ie '\(en'' .ds en \- .el .ds en \(en +.ie '\(lq'' .ds lq \&"\" +.el .ds lq \(lq\" +.ie '\(rq'' .ds rq \&"\" +.el .ds rq \(rq\" +.de q +\\$3\*(lq\\$1\*(rq\\$2 +.. The .I strftime function formats the information from @@ -211,6 +218,11 @@ is replaced by the offset from the Prime Meridian in the format +HHMM or \*-HHMM as appropriate, with positive values representing locations east of Greenwich, or by the empty string if this is not determinable. +The numeric time zone \*-0000 is used when the time is Universal Time +but local time is indeterminate; by convention this is used for +locations while uninhabited, and corresponds to a zero offset when the +time zone abbreviation begins with +.q "\*-" . .TP %% is replaced by a single %. diff --git a/strftime.c b/strftime.c index 984ead5..2bfb6c1 100644 --- a/strftime.c +++ b/strftime.c @@ -500,6 +500,7 @@ label: { long diff; char const * sign; + bool negative; # ifdef TM_GMTOFF diff = t->TM_GMTOFF; @@ -538,7 +539,17 @@ label: continue; # endif # endif - if (diff < 0) { + negative = diff < 0; + if (diff == 0) { +#ifdef TM_ZONE + negative = t->TM_ZONE[0] == '-'; +#else + negative + = (t->tm_isdst < 0 + || tzname[t->tm_isdst != 0][0] == '-'); +#endif + } + if (negative) { sign = "-"; diff = -diff; } else sign = "+"; -- 2.7.4

3 5

Problem with WORK_AROUND_QTBUG_53071
by Bradley White Jan. 8, 2017

Jan. 8, 2017

Happy leap second. In 2016i Pacific/Tongatapu changed to: (1) use numeric time zone abbreviations, and (2) observe DST from the first Sunday in November through the third Sunday in January. That is, its POSIX future rule became "<+13>-13<+14>,M11.1.0,M1.3.0/3". (1) results, under WORK_AROUND_QTBUG_53071, in zic adding a "y2038_boundary - 1" (i.e., 2038-01-19 03:14:07 +00:00) no-op transition to the end of the generated transitions. So, the Pacific/Tongatapu zoneinfo file looks like ... : 2115810000 gmtoff=46800 is_dst=F abbr="+13" 2140606800 gmtoff=50400 is_dst=T abbr="+14" 2147483647 gmtoff=50400 is_dst=T abbr="+14" When loading Pacific/Tongatapu at runtime, (2) results in tzloadbody() generating additional transitions ... : 2140606800 gmtoff=50400 is_dst=T abbr="+14" 2147259600 gmtoff=46800 is_dst=F abbr="+13" 2172661200 gmtoff=50400 is_dst=T abbr="+14" 2178709200 gmtoff=46800 is_dst=F abbr="+13" : When those generated transitions are patched onto the end of the zic transitions, we end up with ... 2115810000 gmtoff=46800 is_dst=F abbr="+13" 2140606800 gmtoff=50400 is_dst=T abbr="+14" 2147483647 gmtoff=50400 is_dst=T abbr="+14" 2172661200 gmtoff=50400 is_dst=T abbr="+14" 2178709200 gmtoff=46800 is_dst=F abbr="+13" This is wrong. The presence of the 2147483647 transition caused us to drop the 2147259600 transition. That is, we lost the shift out of DST at 2038-01-17 02:00:00 +13:00 (2038-01-16 13:00:00 +00:00). One solution would be to trim trailing, no-op transitions from the end of the zic transitions before adding the rule-generated ones. The reference implementation doesn't need them. Bradley

2 7

[PATCH] Update to cite current version of POSIX.1
by Sanjeev Jan. 7, 2017

Jan. 7, 2017

There has been a new Technical Corrigendum issued, and incorporated in the 2016 Edition. Slight reorder of the citation to conform to how Opengroup likes it. --- Theory | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/Theory b/Theory index 22164f4..f2a8dde 100644 --- a/Theory +++ b/Theory @@ -39,10 +39,11 @@ also available. The tz code is upwards compatible with POSIX, an international standard for UNIX-like systems. As of this writing, the current edition of POSIX is: - The Open Group Base Specifications Issue 7 - IEEE Std 1003.1, 2013 Edition - <http://pubs.opengroup.org/onlinepubs/9699919799/> - + IEEE Std 1003.1,2016 Edition + The Open Group Technical Standard Base Specifications, Issue 7 + incorporates IEEE Std 1003.1-2008, + IEEE Std 1003.1-2008/Cor 1-2013, + IEEE Std 1003.1-2008/Cor 2-2016 ----- Names of time zone rules ----- -- 2.10.2

5 4

[PROPOSED] Remove invented North American abbreviations
by Paul Eggert Jan. 5, 2017

Jan. 5, 2017

* NEWS: Document this. * northamerica (America/Anchorage): Use AST/AWT/APT instead of CAT/CAWT/CADT for time stamps before 1968. (Belize, America/Belize, DR, America/Santo_Domingo, America/Miquelon): Use numeric time zone abbreviations instead of invented one. --- NEWS | 11 ++++++++-- northamerica | 71 +++++++++++++++++++++++++++++------------------------------- 2 files changed, 43 insertions(+), 39 deletions(-) diff --git a/NEWS b/NEWS index 5e04e01..780c81c 100644 --- a/NEWS +++ b/NEWS @@ -50,8 +50,15 @@ Unreleased, experimental changes America/Sao_Paulo, Antarctica/Palmer, Atlantic/South_Georgia, Atlantic/Stanley, Pacific/Easter, and Pacific/Galapagos. - Similarly, switch to a numeric time zone abbreviation for Canary - Island time before 1946. + Similarly, switch to numeric time zone abbreviations for St Pierre + and Miquelon time, for half-hour DST in Belize before 1944 and in + the Dominican Republic before 1975, and for Canary Island time + before 1946. + + For Alaska time from 1900 through 1967, instead of "CAT" use the + abbreviation "AST", the abbreviation commonly used at the time + (Atlantic Standard Time had not been standardized yet). Use "AWT" + and "APT" instead of the invented abbreviations "CAWT" and "CAPT". Changes to code diff --git a/northamerica b/northamerica index e1ed9e4..bb0af6c 100644 --- a/northamerica +++ b/northamerica @@ -178,22 +178,6 @@ Zone CST6CDT -6:00 US C%sT Zone MST7MDT -7:00 US M%sT Zone PST8PDT -8:00 US P%sT -# From Bob Devine (1988-01-28): -# ...Alaska (and Hawaii) had the timezone names changed in 1967. -# old new -# Pacific Standard Time(PST) -same- -# Yukon Standard Time(YST) -same- -# Central Alaska S.T. (CAT) Alaska-Hawaii St[an]dard Time (AHST) -# Nome Standard Time (NT) Bering Standard Time (BST) -# -# ...Alaska's timezone lines were redrawn in 1983 to give only 2 tz. -# The YST zone now covers nearly all of the state, AHST just part -# of the Aleutian islands. No DST. - -# From Paul Eggert (1995-12-19): -# The tables below use 'NST', not 'NT', for Nome Standard Time. -# I invented 'CAWT' for Central Alaska War Time. - # From U. S. Naval Observatory (1989-01-19): # USA EASTERN 5 H BEHIND UTC NEW YORK, WASHINGTON # USA EASTERN 4 H BEHIND UTC APR 3 - OCT 30 @@ -250,6 +234,21 @@ Zone PST8PDT -8:00 US P%sT # Samoa standard time # The law doesn't give abbreviations. # +# From Paul Eggert (2016-12-19): +# Here are URLs for the 1918 and 1966 legislation: +# http://uscode.house.gov/statviewer.htm?volume=40&page=451 +# http://uscode.house.gov/statviewer.htm?volume=80&page=108 +# Although the 1918 names were officially "United States Standard +# Eastern Time" and similarly for "Central", "Mountain", "Pacific", +# and "Alaska", in practice "Standard" was placed just before "Time", +# as codified in 1966. In practice, Alaska time was abbreviated "AST" +# before 1968. Summarizing the 1967 name changes: +# 1918 names 1967 names +# -08 Standard Pacific Time (PST) Pacific standard time (PST) +# -09 (unofficial) Yukon (YST) Yukon standard time (YST) +# -10 Standard Alaska Time (AST) Alaska-Hawaii standard time (AHST) +# -11 (unofficial) Nome (NST) Bering standard time (BST) +# # From Paul Eggert (2000-01-08), following a heads-up from Rives McDow: # Public law 106-564 (2000-12-23) introduced ... "Chamorro Standard Time" # for time in Guam and the Northern Marianas. See the file "australasia". @@ -482,7 +481,7 @@ Zone America/Los_Angeles -7:52:58 - LMT 1883 Nov 18 12:07:02 -8:00 US P%sT # Alaska -# AK%sT is the modern abbreviation for -9:00 per USNO. +# AK%sT is the modern abbreviation for -09 per USNO. # # From Paul Eggert (2001-05-30): # Howse writes that Alaska switched from the Julian to the Gregorian calendar, @@ -588,10 +587,8 @@ Zone America/Yakutat 14:41:05 - LMT 1867 Oct 18 -9:00 US AK%sT Zone America/Anchorage 14:00:24 - LMT 1867 Oct 18 -9:59:36 - LMT 1900 Aug 20 12:00 - -10:00 - CAT 1942 - -10:00 US CAT/CAWT 1945 Aug 14 23:00u - -10:00 US CAT/CAPT 1946 # Peace - -10:00 - CAT 1967 Apr + -10:00 - AST 1942 + -10:00 US A%sT 1967 Apr -10:00 - AHST 1969 -10:00 US AH%sT 1983 Oct 30 2:00 -9:00 US Y%sT 1983 Nov 30 @@ -2734,15 +2731,15 @@ Zone America/Barbados -3:58:29 - LMT 1924 # Bridgetown # Belize # Whitman entirely disagrees with Shanks; go with Shanks & Pottenger. # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S -Rule Belize 1918 1942 - Oct Sun>=2 0:00 0:30 HD -Rule Belize 1919 1943 - Feb Sun>=9 0:00 0 S -Rule Belize 1973 only - Dec 5 0:00 1:00 D -Rule Belize 1974 only - Feb 9 0:00 0 S -Rule Belize 1982 only - Dec 18 0:00 1:00 D -Rule Belize 1983 only - Feb 12 0:00 0 S +Rule Belize 1918 1942 - Oct Sun>=2 0:00 0:30 -0530 +Rule Belize 1919 1943 - Feb Sun>=9 0:00 0 CST +Rule Belize 1973 only - Dec 5 0:00 1:00 CDT +Rule Belize 1974 only - Feb 9 0:00 0 CST +Rule Belize 1982 only - Dec 18 0:00 1:00 CDT +Rule Belize 1983 only - Feb 12 0:00 0 CST # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Belize -5:52:48 - LMT 1912 Apr - -6:00 Belize C%sT + -6:00 Belize %s # Bermuda @@ -3014,16 +3011,16 @@ Zone America/Havana -5:29:28 - LMT 1890 # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S -Rule DR 1966 only - Oct 30 0:00 1:00 D -Rule DR 1967 only - Feb 28 0:00 0 S -Rule DR 1969 1973 - Oct lastSun 0:00 0:30 HD -Rule DR 1970 only - Feb 21 0:00 0 S -Rule DR 1971 only - Jan 20 0:00 0 S -Rule DR 1972 1974 - Jan 21 0:00 0 S +Rule DR 1966 only - Oct 30 0:00 1:00 EDT +Rule DR 1967 only - Feb 28 0:00 0 EST +Rule DR 1969 1973 - Oct lastSun 0:00 0:30 -0430 +Rule DR 1970 only - Feb 21 0:00 0 EST +Rule DR 1971 only - Jan 20 0:00 0 EST +Rule DR 1972 1974 - Jan 21 0:00 0 EST # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Santo_Domingo -4:39:36 - LMT 1890 -4:40 - SDMT 1933 Apr 1 12:00 # S. Dom. MT - -5:00 DR E%sT 1974 Oct 27 + -5:00 DR %s 1974 Oct 27 -4:00 - AST 2000 Oct 29 2:00 -5:00 US E%sT 2000 Dec 3 1:00 -4:00 - AST @@ -3313,8 +3310,8 @@ Zone America/Puerto_Rico -4:24:25 - LMT 1899 Mar 28 12:00 # San Juan # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Miquelon -3:44:40 - LMT 1911 May 15 # St Pierre -4:00 - AST 1980 May - -3:00 - PMST 1987 # Pierre & Miquelon Time - -3:00 Canada PM%sT + -3:00 - -03 1987 # Pierre & Miquelon Time + -3:00 Canada -03/-02 # St Vincent and the Grenadines # See America/Port_of_Spain. -- 2.7.4

3 6

question about mktime_tzname()
by Kees Dekker Jan. 5, 2017

Jan. 5, 2017

Hi, I'm running into a potential bug. Please also see the attached C-source file for a reproduction. Reproduction steps: 1. Build tz code, in such way that a libtz.a exists 2. Compile attached source with (e.g. on Linux): gcc -g -o tztestcase2016j tztestcase.c -L <tzlibdir> -ltz 3. Checking the same test case source code with a system library (instead of IANA libtz.a) can be achieved by omitting -L and -l flags in previous command (see #2). It does not make much sense which version of tzcode is used, I tried 2013i and 2016j and both show the same behavior. The mktime() code returns -3600, while I expect 0. Because the TZ zone is explicitly specified, EST5EDT is GMT-5. So the provided time stamp (31-Jan-1969, 19:00) is exactly the same as UTC value 0 (1-Jan-1970, 00:00 GMT). Both Linux and Windows with system libraries return 0 in this specific case (I used these for reference). The remainder of this email is based on the tzcode2016j source code (e.g. for used line numbers). The provided TZ value is parsed in tzparse() and results in sp->ttis[0] set as DST value, and sp->ttis[1] as standard time value. This is at least contrary to in the else part of the if (*name == ',' || *name == ';') block (there DST is saved in sp->ttis[1]). Just grep on init_ttinfo() calls in localtime.c. However, in localsub(), around line 1428, the i becomes sp->defaulttype (which is zero), i.e. points to the DST value of sp->ttis[], which is assigned to ttisp. As result, because t is below sp->ats[0], DST takes into effect, which is incorrect, as everything after the last Sunday in October and before the first Sunday in April (see attachment, TZ="EST5EDT,M4.1.0/02:00,M10.5.0/02:00") is assumed to be standard time. I'm not sure whether I draw the right conclusion, but because the incorrect assumption of using DST, mktime() returns -3600 (on hour off) instead of the expected 0. Is this conclusion correct? I'm not sure how to fix it. When changing the call to init_ttinfo() and effectively swapping DST and standard time (also for symmetry with the else part) in sp-ttis[] (0 to 1 and 1 to 0) + keeping sp->defaulttype = 0 solved this problem, but introduces other conversion errors around DSTchanges (I don't have yet an reproduction, but can make one if needed). The sp->default type is used (in localsub ()) when if (sp->timecnt == 0 || t < sp->ats[0]). The other approach is to assign sp->defaulttype = 1 when the init_ttinfo() calls are not swapped. Anyhow, there is a tight relationship between the value of sp->defaulttype and the order in which DST/standard times are written in sp->ttis[]. If the previous idea is incorrect (and I guess it is), additional code may be needed in time2sub() if yourtm.tm_isdst == -1. In that case, the provided data in yourtm should be checked whether DST is (or is not) into effect. The found mytm struct should match. Otherwise a DST correction is needed (one-hour shift). The current code mistakenly uses DST, and that is why (if I understand all well) mktime() now returns -3600. If I was not able to explain the issue correctly, please let me know. I'm not sure to understand what's going wrong now, but may be, the provided attachment will help in giving better understanding. Because the provided date is near 1970, quite few steps are needed to see what's happing in localtime.c. Regards, Kees Dekker PS. This email has been sent assuming that attachments will not get lost. Otherwise, just copy paste the code below and save to e.g. tztestcase.c. #ifdef _WIN32 #define _CRT_SECURE_NO_WARNINGS #endif #include <time.h> #include <stdio.h> #include <stdlib.h> int main(void) { int ret = 0; const char *months[] = { "Jan", "Feb", "Mar", "April", "May", "June", "July", "Aug", "Sep", "Oct", "Nov", "Dec" }; const char *days[] = { "Sun", "Mon", "Tue", "Wed", "Tur", "Fri", "Sat" }; /* DST switch in April in first Sunday and October, last Sunday */ putenv("TZ=EST5EDT,M4.1.0/02:00,M10.5.0/02:00"); /* January, 1970, invalid input for tm_mday (0 instead 1..31) */ /* non-normalized input for minutes: 1140/60 = 19, so 19:00 EST5EDT time, which is 5 hours before GMT, and should result in t == 0 below */ /* let system figure out whether DST is effect */ struct tm tmp = { 0, 1140, 0, 0, 0, 70, -858993460, -858993460, -1}; printf("enter mktime with: %04d/%s/%02d %02d:%02d:%02d, week day: %d, year day: %d, dst: %d\n", tmp.tm_year + 1900, months[tmp.tm_mon], tmp.tm_mday, tmp.tm_hour, tmp.tm_min, tmp.tm_sec, tmp.tm_wday, tmp.tm_yday, tmp.tm_isdst); time_t t = mktime(&tmp); /* expect: t == 0, DST is off, time is exactly at the boundary of lowest possible UTC value */ printf("the return value of mktime is: %lld\n", (long long)t); printf("normalized times: %04d/%s/%02d %02d:%02d:%02d, week day: %s, year day: %d, dst: %d\n", tmp.tm_year + 1900, months[tmp.tm_mon], tmp.tm_mday, tmp.tm_hour, tmp.tm_min, tmp.tm_sec, days[tmp.tm_wday], tmp.tm_yday, tmp.tm_isdst); if (t >= 0) { printf("tz=%s, %s\n", tzname[0], tzname[1]); } return 0; }

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