August 2015 - tz - lists.iana.org

proposed time zone package changes (Samoa, Factory, et al.)
by Arthur David Olson 28 Aug '19

28 Aug '19

Below find proposed time zone package changes; the executive summary: * Makefile Change LOCALTIME default from "Factory" to "GMT"; do not compile "factory" file (but keep it in the distribution). * Theory Remove reference to "Factory" zone. * australasia Change end of DST in Samoa in 2011 from 2011-04-03 0:00 to 2011-04-03 1:00 (thanks to Raymond Hughes for a reference). * localtime.c Initialize ttinfo structures filled by tzparse (thanks to Ravindra for reporting a valgrind warning). * zic.c Fix generation of POSIX strings for zones with rules using "weekday<=n" forms of dates (thanks to Lei Liu for finding the problem). Also, limit output for non-POSIX-specificable zones defined to follow the same rules every year. (Note that no zones of either of the above types appear in the distribution; these changes cater to add-on zones). If no problems are found, 2010n will appear on 2010-10-25. --ado diff -r -c old/Makefile new/Makefile *** old/Makefile Mon Sep 27 09:24:25 2010 --- new/Makefile Tue Oct 12 12:36:50 2010 *************** *** 1,5 **** # <pre> ! # @(#)Makefile 8.8 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. --- 1,5 ---- # <pre> ! # @(#)Makefile 8.9 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. *************** *** 12,18 **** # make zonenames # to get a list of the values you can use for LOCALTIME. ! LOCALTIME= Factory # If you want something other than Eastern United States time as a template # for handling POSIX-style time zone environment variables, --- 12,18 ---- # make zonenames # to get a list of the values you can use for LOCALTIME. ! LOCALTIME= GMT # If you want something other than Eastern United States time as a template # for handling POSIX-style time zone environment variables, *************** *** 262,269 **** DOCS= README Theory $(MANS) date.1 Makefile PRIMARY_YDATA= africa antarctica asia australasia \ europe northamerica southamerica ! YDATA= $(PRIMARY_YDATA) pacificnew etcetera factory backward ! NDATA= systemv SDATA= solar87 solar88 solar89 TDATA= $(YDATA) $(NDATA) $(SDATA) TABDATA= iso3166.tab zone.tab --- 262,269 ---- DOCS= README Theory $(MANS) date.1 Makefile PRIMARY_YDATA= africa antarctica asia australasia \ europe northamerica southamerica ! YDATA= $(PRIMARY_YDATA) pacificnew etcetera backward ! NDATA= systemv factory SDATA= solar87 solar88 solar89 TDATA= $(YDATA) $(NDATA) $(SDATA) TABDATA= iso3166.tab zone.tab diff -r -c old/Theory new/Theory *** old/Theory Mon Sep 27 09:24:25 2010 --- new/Theory Tue Oct 12 12:36:50 2010 *************** *** 1,4 **** ! @(#)Theory 8.4 This file is in the public domain, so clarified as of 2009-05-17 by Arthur David Olson. --- 1,4 ---- ! @(#)Theory 8.5 This file is in the public domain, so clarified as of 2009-05-17 by Arthur David Olson. *************** *** 287,294 **** See the file `backward' for most of these older names (e.g. `US/Eastern' instead of `America/New_York'). The other old-fashioned names still supported are ! `WET', `CET', `MET', `EET' (see the file `europe'), ! and `Factory' (see the file `factory'). ----- Time zone abbreviations ----- --- 287,293 ---- See the file `backward' for most of these older names (e.g. `US/Eastern' instead of `America/New_York'). The other old-fashioned names still supported are ! `WET', `CET', `MET', and `EET' (see the file `europe'). ----- Time zone abbreviations ----- diff -r -c old/australasia new/australasia *** old/australasia Mon Sep 27 09:24:27 2010 --- new/australasia Tue Oct 12 13:14:56 2010 *************** *** 1,5 **** # <pre> ! # @(#)australasia 8.18 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. --- 1,5 ---- # <pre> ! # @(#)australasia 8.19 # This file is in the public domain, so clarified as of # 2009-05-17 by Arthur David Olson. *************** *** 487,497 **** # http://www.parliament.gov.ws/documents/acts/Daylight%20Saving%20Act%20%2020… # </a> Zone Pacific/Apia 12:33:04 - LMT 1879 Jul 5 -11:26:56 - LMT 1911 -11:30 - SAMT 1950 # Samoa Time -11:00 - WST 2010 Sep 26 ! -11:00 1:00 WSDT 2011 Apr 3 -11:00 - WST # Solomon Is --- 487,507 ---- # http://www.parliament.gov.ws/documents/acts/Daylight%20Saving%20Act%20%2020… # </a> + # From Raymond Hughes (2010-10-07): + # Please see + # <a href="http://www.mcil.gov.ws"> + # http://www.mcil.gov.ws + # </a>, + # the Ministry of Commerce, Industry and Labour (sideframe) "Last Sunday + # September 2010 (26/09/10) - adjust clocks forward from 12:00 midnight + # to 01:00am and First Sunday April 2011 (03/04/11) - adjust clocks + # backwards from 1:00am to 12:00am" + Zone Pacific/Apia 12:33:04 - LMT 1879 Jul 5 -11:26:56 - LMT 1911 -11:30 - SAMT 1950 # Samoa Time -11:00 - WST 2010 Sep 26 ! -11:00 1:00 WSDT 2011 Apr 3 1:00 -11:00 - WST # Solomon Is diff -r -c old/localtime.c new/localtime.c *** old/localtime.c Mon Sep 27 09:24:26 2010 --- new/localtime.c Tue Oct 12 12:36:51 2010 *************** *** 5,11 **** #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)localtime.c 8.14"; #endif /* !defined NOID */ #endif /* !defined lint */ --- 5,11 ---- #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)localtime.c 8.15"; #endif /* !defined NOID */ #endif /* !defined lint */ *************** *** 914,919 **** --- 914,920 ---- register unsigned char * typep; register char * cp; register int load_result; + static struct ttinfo zttinfo; INITIALIZE(dstname); stdname = name; *************** *** 986,991 **** --- 987,993 ---- /* ** Two transitions per year, from EPOCH_YEAR forward. */ + sp->ttis[0] = sp->ttis[1] = zttinfo; sp->ttis[0].tt_gmtoff = -dstoffset; sp->ttis[0].tt_isdst = 1; sp->ttis[0].tt_abbrind = stdlen + 1; *************** *** 1099,1106 **** } /* ** Finally, fill in ttis. - ** ttisstd and ttisgmt need not be handled. */ sp->ttis[0].tt_gmtoff = -stdoffset; sp->ttis[0].tt_isdst = FALSE; sp->ttis[0].tt_abbrind = 0; --- 1101,1108 ---- } /* ** Finally, fill in ttis. */ + sp->ttis[0] = sp->ttis[1] = zttinfo; sp->ttis[0].tt_gmtoff = -stdoffset; sp->ttis[0].tt_isdst = FALSE; sp->ttis[0].tt_abbrind = 0; *************** *** 1113,1118 **** --- 1115,1121 ---- dstlen = 0; sp->typecnt = 1; /* only standard time */ sp->timecnt = 0; + sp->ttis[0] = zttinfo; sp->ttis[0].tt_gmtoff = -stdoffset; sp->ttis[0].tt_isdst = 0; sp->ttis[0].tt_abbrind = 0; diff -r -c old/zic.c new/zic.c *** old/zic.c Mon Sep 27 09:24:26 2010 --- new/zic.c Tue Oct 12 13:37:29 2010 *************** *** 3,9 **** ** 2006-07-17 by Arthur David Olson. */ ! static char elsieid[] = "@(#)zic.c 8.22"; #include "private.h" #include "locale.h" --- 3,9 ---- ** 2006-07-17 by Arthur David Olson. */ ! static char elsieid[] = "@(#)zic.c 8.24"; #include "private.h" #include "locale.h" *************** *** 1881,1896 **** register int week; if (rp->r_dycode == DC_DOWGEQ) { ! week = 1 + rp->r_dayofmonth / DAYSPERWEEK; ! if ((week - 1) * DAYSPERWEEK + 1 != rp->r_dayofmonth) return -1; } else if (rp->r_dycode == DC_DOWLEQ) { if (rp->r_dayofmonth == len_months[1][rp->r_month]) week = 5; else { ! week = 1 + rp->r_dayofmonth / DAYSPERWEEK; ! if (week * DAYSPERWEEK - 1 != rp->r_dayofmonth) return -1; } } else return -1; /* "cannot happen" */ (void) sprintf(result, "M%d.%d.%d", --- 1881,1896 ---- register int week; if (rp->r_dycode == DC_DOWGEQ) { ! if ((rp->r_dayofmonth % DAYSPERWEEK) != 1) return -1; + week = 1 + rp->r_dayofmonth / DAYSPERWEEK; } else if (rp->r_dycode == DC_DOWLEQ) { if (rp->r_dayofmonth == len_months[1][rp->r_month]) week = 5; else { ! if ((rp->r_dayofmonth % DAYSPERWEEK) != 0) return -1; + week = rp->r_dayofmonth / DAYSPERWEEK; } } else return -1; /* "cannot happen" */ (void) sprintf(result, "M%d.%d.%d", *************** *** 2018,2023 **** --- 2018,2024 ---- register char * envvar; register int max_abbr_len; register int max_envvar_len; + register int prodstic; /* all rules are min to max */ max_abbr_len = 2 + max_format_len + max_abbrvar_len; max_envvar_len = 2 * max_abbr_len + 5 * 9; *************** *** 2032,2037 **** --- 2033,2039 ---- timecnt = 0; typecnt = 0; charcnt = 0; + prodstic = zonecount == 1; /* ** Thanks to Earl Chew ** for noting the need to unconditionally initialize startttisstd. *************** *** 2053,2058 **** --- 2055,2062 ---- updateminmax(rp->r_loyear); if (rp->r_hiwasnum) updateminmax(rp->r_hiyear); + if (rp->r_lowasnum || rp->r_hiwasnum) + prodstic = FALSE; } } /* *************** *** 2075,2080 **** --- 2079,2094 ---- if (max_year <= INT_MAX - YEARSPERREPEAT) max_year += YEARSPERREPEAT; else max_year = INT_MAX; + /* + ** Regardless of any of the above, + ** for a "proDSTic" zone which specifies that its rules + ** always have and always will be in effect, + ** we only need one cycle to define the zone. + */ + if (prodstic) { + min_year = 1900; + max_year = min_year + YEARSPERREPEAT; + } } /* ** For the benefit of older systems,

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Proposal: validation text file with releases
by Jon Skeet 19 Dec '16

19 Dec '16

Background: I'm the primary developer for Noda Time <http://nodatime.org> which consumes the tz data. I'm currently refactoring the code to do this... and I've come across some code (originally ported from Joda Time) which I now understand in terms of what it's doing, but not exactly why. For a little while now, the Noda Time source repo has included a text dump file <https://github.com/nodatime/nodatime/blob/master/src/NodaTime.Test/TestData…>, containing a text dump of every transition (up to 2100, at the moment) for every time zone. It looks like this, picking just one example: Zone: Africa/Maseru LMT: [StartOfTime, 1892-02-07T22:08:00Z) +01:52 (+00) SAST: [1892-02-07T22:08:00Z, 1903-02-28T22:30:00Z) +01:30 (+00) SAST: [1903-02-28T22:30:00Z, 1942-09-20T00:00:00Z) +02 (+00) SAST: [1942-09-20T00:00:00Z, 1943-03-20T23:00:00Z) +03 (+01) SAST: [1943-03-20T23:00:00Z, 1943-09-19T00:00:00Z) +02 (+00) SAST: [1943-09-19T00:00:00Z, 1944-03-18T23:00:00Z) +03 (+01) SAST: [1944-03-18T23:00:00Z, EndOfTime) +02 (+00) I use this file for confidence when refactoring my time zone handling code - if the new code comes up with the same set of transitions as the old code, it's probably okay. (This is just one line of defence, of course - there are unit tests, though not as many as I'd like.) It strikes me that having a similar file (I'm not wedded to the format, but it should have all the same information, one way or another) released alongside the main data files would be really handy for *all* implementors - it would be a good way of validating consistency across multiple platforms, with the release data being canonical. For any platforms which didn't want to actually consume the rules as rules, but just wanted a list of transitions, it could even effectively replace their use of the data. One other benefit: diffing the dump between two releases would make it clear what had changed in *effect*, rather than just in terms of rules. One sticking point is size. The current file for Noda Time is about 4MB, although it zips down to about 300K. Some thoughts around this: - We wouldn't need to distribute it in the same file as the data - just as we have data and code file, there could be a "textdump" file or whatever we'd want to call it. These could be retroactively generated for previous releases, too. - As you can see, there's redundancy in the format above, in that it's a list of "zone intervals" (as I call them in Noda Time) rather than a list of transitions - the end of each interval is always the start of the next interval. - For zones which settle into an infinite daylight saving pattern, I currently generate from the start of time to 2100 (and then a single zone interval for the end of time as Noda Time understands it; we'd need to work out what form that would take, if any). If we decided that "year of release + 30 years" was enough, that would cut down the size considerably. Any thoughts? If the feeling is broadly positive, the next step would be to nail down the text format, then find a willing victim/volunteer to write the C code. (You really don't want me writing C...) Jon

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zic changes (2/2)
by Arthur David Olson 09 Mar '16

09 Mar '16

And now, the update. These changes arrange things so that binary files include "transition" entries for minimum time values; these entries eliminate localtime guesswork in handling low-valued time stamps. The bad news: binary files grow slightly as a result of these changes. The good news: there are no changes in the output of "zdump -v" applied to before-and-after versions of all the binary files generated by a "make install." Changes are attached and appear in mangled form below; these are relative to the github version of zic.c after the rollback in the earlier message today. @dashdashado 1.2 2805 lines 1.4 2813 lines *** /tmp/,azic.c 2014-05-01 01:51:36.998933800 -0400 --- /tmp/,bzic.c 2014-05-01 01:51:37.092534000 -0400 *************** *** 1480,1493 **** fromi = 0; while (fromi < timecnt && attypes[fromi].at < min_time) ++fromi; - if (isdsts[0] == 0) - while (fromi < timecnt && attypes[fromi].type == 0) - ++fromi; /* handled by default rule */ for ( ; fromi < timecnt; ++fromi) { ! if (toi != 0 && ((attypes[fromi].at + gmtoffs[attypes[toi - 1].type]) <= ! (attypes[toi - 1].at + gmtoffs[toi == 1 ? 0 ! : attypes[toi - 2].type]))) { attypes[toi - 1].type = attypes[fromi].type; continue; --- 1480,1490 ---- fromi = 0; while (fromi < timecnt && attypes[fromi].at < min_time) ++fromi; for ( ; fromi < timecnt; ++fromi) { ! if (toi > 1 && ((attypes[fromi].at + gmtoffs[attypes[toi - 1].type]) <= ! (attypes[toi - 1].at + ! gmtoffs[attypes[toi - 2].type]))) { attypes[toi - 1].type = attypes[fromi].type; continue; *************** *** 1532,1537 **** --- 1529,1541 ---- --timecnt32; ++timei32; } + /* + ** Output an INT32_MIN "transition" if appropriate--see below. + */ + if (timei32 > 0 && ats[timei32] > INT32_MIN) { + --timei32; + ++timecnt32; + } while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1])) --leapcnt32; while (leapcnt32 > 0 && !is32(trans[leapi32])) { *************** *** 1698,1704 **** #undef DO for (i = thistimei; i < thistimelim; ++i) if (pass == 1) ! puttzcode(ats[i], fp); else puttzcode64(ats[i], fp); for (i = thistimei; i < thistimelim; ++i) { unsigned char uc; --- 1702,1713 ---- #undef DO for (i = thistimei; i < thistimelim; ++i) if (pass == 1) ! /* ! ** Output an INT32_MIN "transition" ! ** if appropriate--see above. ! */ ! puttzcode(((ats[i] < INT32_MIN) ? ! INT32_MIN : ats[i]), fp); else puttzcode64(ats[i], fp); for (i = thistimei; i < thistimelim; ++i) { unsigned char uc; *************** *** 2176,2183 **** if (usestart) { addtt(starttime, type); usestart = FALSE; ! } else if (stdoff != 0) ! addtt(min_time, type); } else for (year = min_year; year <= max_year; ++year) { if (useuntil && year > zp->z_untilrule.r_hiyear) break; --- 2185,2191 ---- if (usestart) { addtt(starttime, type); usestart = FALSE; ! } else addtt(min_time, type); } else for (year = min_year; year <= max_year; ++year) { if (useuntil && year > zp->z_untilrule.r_hiyear) break;

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Request to include www.timejones.com - tz database version 2014.8
by Web Master 09 Dec '15

09 Dec '15

Hi, Greetings! First of all immense thanks for the introduction of tz database to the world. We are writing from www.timejones.com, an ultra simple time and weather services portal that helps people with time and weather information for 150000 places on Earth. We have developed this web site using tz database version 2014.8/ PHP 5.4.39 and hosted on a Apache/2.2.29. Could you please kindly include www.timejones.com under the section "Web sites using recent versions of the tz database" in http://cs.ucla.edu/~eggert/tz/tz-link.htm ? Thanks in advance! Best Regards, Webmaster(a)timejones.com

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South Australia may move clocks 30 minutes
by Paul Eggert 10 Sep '15

10 Sep '15

The South Australian government is considering changing their clocks by 30 minutes. The government would prefer advancing clocks by 30 minutes to match the time on the east coast. The public is split. Much of the resistance is coming from the west part of the state, where locals worry about their children leaving for school in the dark, and the government is prepared to consider changing school hours to address this. Another possibility is retarding clocks by 30 minutes; this would move closer to solar time, and would align better with Asia. This change would probably affect Broken Hill as well. Northern Territory will be consulted but seems less inclined to change. The consultation process will take at least two months. The government's website crashed as citizens went online to give their opinion. Sources: Nicholson M. South Australia has the most ridiculous time zone, and might be about to change it. Junkee 2015-02-06. http://junkee.com/south-australia-has-the-most-ridiculous-time-zone-and-mig… Ball G, Clift J, Coote G. Broken Hill urged to air views on proposed time zone change for South Australia. ABC News (Australia), 2015-02-06. http://www.abc.net.au/news/2015-02-06/broken-hill-community-urged-air-views… SA considers changing time zone to match eastern states. 9NEWS 2015-02-05. http://www.9news.com.au/national/2015/02/05/12/15/sa-considers-changing-tim… South Australians remain divided on whether it is time for the time to change. 9NEWS 2015-02-06. http://www.9news.com.au/national/2015/02/06/21/03/south-australians-remain-…

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question regarding 'timezone' variable
by Kees Dekker 02 Sep '15

02 Sep '15

Hi, When USG_COMPAT is set, in localtime.c a long timezone (and int daylight) is declared. In strftime.c, also timezone is used, but no reference to 'extern long timezone' is define, neither do any of the provided header files. On most *NIX platforms, a system 'timezone' variable exists (see e.g. man tzset). My concerns are: a. The provided variable in localtime.c may conflict with the system one. b. The used variable in strftime.c may not related to the variable in localtime.c I think that compilers/linkers may complain about duplicate 'timezone' variables, or probably silently map the local timezone variable to the same one. Question: Is behavior intended? Or do I miss something? Regards, Kees

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[PROPOSED PATCH] Fix localtime bug with Anchorage after 2037
by Paul Eggert 28 Aug '15

28 Aug '15

* NEWS: Document this. * localtime.c (tzloadbody): Handle America/Anchorage after 2037, even though the sum of the abbreviations' sizes (42) plus the sum of the extended abbreviations' sizes (10) exceeds TZ_MAX_CHARS (50). Do this by reusing existing abbreviations. Thanks to Bradley White for reporting the bug. Perhaps we should also consider increasing TZ_MAX_CHARS from its currently-low value. --- NEWS | 8 +++++++ localtime.c | 71 +++++++++++++++++++++++++++++++++++++++---------------------- 2 files changed, 54 insertions(+), 25 deletions(-) diff --git a/NEWS b/NEWS index b477250..ffe3fb2 100644 --- a/NEWS +++ b/NEWS @@ -1,5 +1,13 @@ News for the tz database +Unreleased, experimental changes + + Changes affecting code + + localtime no longer mishandles America/Anchorage after 2037. + (Thanks to Bradley White for reporting the bug.) + + Release 2015f - 2015-08-10 18:06:56 -0700 Changes affecting future time stamps diff --git a/localtime.c b/localtime.c index ded8f7b..ac34e5d 100644 --- a/localtime.c +++ b/localtime.c @@ -569,31 +569,52 @@ tzloadbody(char const *name, struct state *sp, bool doextend, up->buf[nread - 1] = '\0'; if (tzparse(&up->buf[1], ts, false) - && ts->typecnt == 2 - && sp->charcnt + ts->charcnt <= TZ_MAX_CHARS) { - for (i = 0; i < 2; ++i) - ts->ttis[i].tt_abbrind += - sp->charcnt; - for (i = 0; i < ts->charcnt; ++i) - sp->chars[sp->charcnt++] = - ts->chars[i]; - i = 0; - while (i < ts->timecnt && - ts->ats[i] <= - sp->ats[sp->timecnt - 1]) - ++i; - while (i < ts->timecnt && - sp->timecnt < TZ_MAX_TIMES) { - sp->ats[sp->timecnt] = - ts->ats[i]; - sp->types[sp->timecnt] = - sp->typecnt + - ts->types[i]; - ++sp->timecnt; - ++i; - } - sp->ttis[sp->typecnt++] = ts->ttis[0]; - sp->ttis[sp->typecnt++] = ts->ttis[1]; + && ts->typecnt == 2) { + + /* Attempt to reuse existing abbreviations. + Without this, America/Anchorage would stop + working after 2037 when TZ_MAX_CHARS is 50, as + sp->charcnt equals 42 (for LMT CAT CAWT CAPT AHST + AHDT YST AKDT AKST) and ts->charcnt equals 10 + (for AKST AKDT). Reusing means sp->charcnt can + stay 42 in this example. */ + int gotabbr = 0; + int charcnt = sp->charcnt; + for (i = 0; i < 2; i++) { + char *tsabbr = ts->chars + ts->ttis[i].tt_abbrind; + int j; + for (j = 0; j < charcnt; j++) + if (strcmp(sp->chars + j, tsabbr) == 0) { + ts->ttis[i].tt_abbrind = j; + gotabbr++; + break; + } + if (! (j < charcnt)) { + int tsabbrlen = strlen(tsabbr); + if (j + tsabbrlen < TZ_MAX_CHARS) { + strcpy(sp->chars + j, tsabbr); + charcnt = j + tsabbrlen + 1; + ts->ttis[i].tt_abbrind = j; + gotabbr++; + } + } + } + if (gotabbr == 2) { + sp->charcnt = charcnt; + for (i = 0; i < ts->timecnt; i++) + if (sp->ats[sp->timecnt - 1] < ts->ats[i]) + break; + while (i < ts->timecnt + && sp->timecnt < TZ_MAX_TIMES) { + sp->ats[sp->timecnt] = ts->ats[i]; + sp->types[sp->timecnt] = (sp->typecnt + + ts->types[i]); + sp->timecnt++; + i++; + } + sp->ttis[sp->typecnt++] = ts->ttis[0]; + sp->ttis[sp->typecnt++] = ts->ttis[1]; + } } } if (sp->timecnt > 1) { -- 2.1.4

1 0

North Korea ultimatum deadline time confusion
by Paul Eggert 22 Aug '15

22 Aug '15

North Korea has delivered a 48-hour ultimatum to the South Korean Defense Ministry, saying that it will respond militarily unless South Korea stops broadcasting propaganda via loudspeakers over the border. There seems to be some confusion about the ultimatum's exact deadline. Ju-Min Park and James Person of Reuters report that although the ultimatum is "uncharacteristically specific", the deadline is "around 5 p.m. (0800 GMT) on Saturday in Seoul". Could the time confusion be due to the recent time zone change in North Korea? Park JM, Pearson J. North Korea goes on war footing against South Korea as deadline looms. Reuters 2015-08-21 12:53 -0400. http://www.reuters.com/article/2015/08/21/us-northkorea-southkorea-border-i… $ date -u; TZ=Asia/Pyongyang date; TZ=Asia/Seoul date Fri Aug 21 17:12:37 UTC 2015 Sat Aug 22 01:42:37 KST 2015 Sat Aug 22 02:12:37 KST 2015

2 3

Time zone humor
by Matt Johnson 18 Aug '15

18 Aug '15

For the art file http://www.maniacworld.com/time-zones-explained.html Enjoy!

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tzfiles contain Unix epoch for the first transition time
by Eric Erhardt 15 Aug '15

15 Aug '15

I am working on enabling the .NET TimeZoneInfo class to read time zone information from tzfiles. I've hit a snag with the latest tzdata 2015f. (I'm not sure when this change started, but the problem doesn't occur with the tzfiles that are shipped with an Ubuntu 14.04 distribution.) The problem is that the 2015f version of the tzdata contains an initial "Transition Time" that is out of order. The beginning of the America/Chicago tzfile looks like the following: Transition Time Transition Offset 01/01/1970 00:00:00 -05:50:36 11/18/1883 18:00:00 -06:00:00 03/31/1918 08:00:00 -05:00:00 DST 10/27/1918 07:00:00 -06:00:00 Notice the first entry is for 1970, and then the next entry is for 1883. This breaks the documentation in 'man tzfile': The above header is followed by tzh_timecnt four-byte values of type long, sorted in ascending order. These values are written in "standard" byte order. Each is used as a transition time (as returned by time(2)) at which the rules for computing local time change. This causes the TimeZoneInfo parsing code to throw an exception because it is assuming these transitions are sorted in ascending order. Is this an intentional change in the tzfiles? If so, will the tzfile man page be updated for this change? Eric Erhardt

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