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Inappropriate project direction
by Stephen Colebourne Feb. 12, 2018

Feb. 12, 2018

In the last few years, the following changes have been made to the tzdb project. Each of these - added no value - had a cost that far exceeded the benefits - should not have happened 1) Removal of Zone definitions from many countries. While the Zone definitions may have been the same across different countries, it was never appropriate to merge the time-zones of multiple different countries (backzone being the result). - the change caused LMT values to be lost - downstream consumers had to change logic wrt the meaning of backzone - it was culturally insensitive to not provide a primary Zone entry for some countries 2) Removal of textual short zone names. While these names may well have been invented in some cases, the had often become de facto standards - end-users complained about the loss of textual names - downstream consumers had to change logic to handle numeric-style identifiers 3) Move to a niche archive format The main archive format was changed from the well-known and widely supported gz to the niche lz format. There was and is no justification for using a niche format on a project as important as this one. - downstream consumers need to find and use the niche format - Windows does not have proper support for the niche format 4) Negative SAVE values Despite being a known fact in tzdb since 2005, and despite being warned not to in advance, a decision to re-interpret the meaning of Ireland DST was pushed through. - downstream consumers broke - the interaction with CLDR is incompatible with negative DST - the change has no impact on actual times - even if someone thought it was broken, there are no benefits to making the change 5) Fractional seconds A desire to fix subsecond data from over 50 years ago. - downstream consumers will break - the number of people who care is vanishingly small Were recent discussions a one-off, I might be prepared to let things lie, but as can be seen, there is a pattern here. Not one of these changes has added value to the project. Not one of them has been necessary to the primary mission of recording what governments are doing to their clocks now, nor even in the last 40 years. Worse, the majority are driven by a notion that getting the data "pure" trumps all problems reported by downstream consumers. It is long past time to accept that tzdb needs to focus on the primary mission - recording current government changes in a stable, backwards compatible manner. Tinkering needs to stop. Stephen

10 15

EP vote on EU DST; afternoon gloom in Scotland
by Paul Eggert Feb. 11, 2018

Feb. 11, 2018

On Thursday, the European Parliament voted 384-152 to pass a nonbinding resolution calling for the European Commission to re-evaluate the current system of daylight saving time in Europe. An article about this and how it's entangled with European politics can be found here: Yeginsu C. Daylight saving time: what's it good for? European lawmakers ask. New York Times. 2018-02-09. https://www.nytimes.com/2018/02/09/world/europe/europe-daylight-saving.html My favorite quote is about the UK Daylight Saving Bill 2010-12. Yeginsu writes: "That bill was met with fierce resistance in places like Scotland, where residents argued that they liked the afternoon gloom just fine."

2 1

License of lzip, lzlib and pdlzip
by Antonio Diaz Diaz Feb. 11, 2018

Feb. 11, 2018

Bryan Smith wrote: > There is still a heavy copyleft (e.g., GPL) v. non-copyleft FLOSS > debate that rages on, with various people putting various values -- > from nothing to everything -- on that. lzip -- or more problematic, > it's lzlib -- is GPLv2 -- not even LGPL -- which has some asterisks > for commercial developers. I don't know the state of public domain > lzip (pdlzip), but it seems to be good enough for any decompression > (and most general compression). Thanks for your comments. I'll just add a clarification about lzip licensing. Lzip itself is GPL version 2 or later. Lzlib was also GPLv2+, but a year ago (in version 1.9) the license was changed to 2-clause BSD as you can see in lzlib's homepage[1]. There is also another BSD licensed library (libarchive) able to (de)compress lzip files and lzip-compressed tar archives. Pdlzip has a 2-clause BSD license[2]. It is maintained and fully compatible with the lzip format for both compression and decompression. [1] http://www.nongnu.org/lzip/lzlib.html [2] http://www.nongnu.org/lzip/pdlzip.html Best regards, Antonio.

1 0

Fractional seconds in zic input
by Paul Eggert Feb. 10, 2018

Feb. 10, 2018

For many years I've chafed at tzdata's lack of support for fractional seconds. We have good evidence of well-established standard-time UT offsets that were not multiples of one second; for example, the Netherlands before 1937. These can't be recorded in tzdata except as comments. Ideally tzcode would support fractional-second times and UT offsets all the way down the chain. This would mean changes to the tz binary format and to the runtime API, though, which is not something we'd do lightly, if ever. However, it's easy to change the zic spec to allow fractional seconds, and to change zic to accept and ignore the fractions, so that fractional seconds can be documented more formally in the data; this could well be useful to applications other than tzcode. Proposed patch attached, hairy sscanf format and all. This patch does not actually change the data, as we'll need time, and/or a procedure to automatically generate data compatible with zic 2018c and earlier.

17 51

tzdata source compatibility
by christos＠zoulas.com Feb. 7, 2018

Feb. 7, 2018

Hi, Here's my 5 cents to the tzdb compatibility discussion: - Things need to move forward; half-measures like "functional comments" end up hurting in the long term and create unpredictable behavior. - There are other users of the tzdata "source" so compatibility needs to be maintained for "some time". - On the other hand, we can't be held hostage forever; people who write parsers, should be able to maintain the code. Straw man proposal: 1. Create a version ChangeLog with tzdb; it should be simple: - a version number (for reference) - the release date (to guide expiration) - an explanation to what changed in the format (for parser writers) 2. Maintain two copies of the source; the current one, and the previous version in a "compat" subdirectory. Expire "compat" a year after the release of the next version. I hope this is helpful, christos

5 6

New open-source zoneinfo compiler
by Kerry Shetline Feb. 5, 2018

Feb. 5, 2018

Hi, In case this might be of use to others, I’ve posted a new project on GitHub, https://github.com/kshetline/compact-time-zone-generator <https://github.com/kshetline/compact-time-zone-generator>. This is a parser and compiler written in Java that produces output primarily meant to be used with web apps. The project also includes an Angular demo app which consumes this format of compiled time zone data. The README for the project explains more, and provides some demo links, which might help decide if this is a project that might be useful to share on the discussion list. -Kerry

2 1

[PROPOSED] Fix 0.5 s bug for Jakarta in 1923
by Paul Eggert Feb. 5, 2018

Feb. 5, 2018

* ziguard.awk: Fix bug for Asia/Jakarta: the 1923-12-31 transition was off by 0.5 s when fractional seconds were enabled. --- ziguard.awk | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/ziguard.awk b/ziguard.awk index 795b4ef..70376b7 100644 --- a/ziguard.awk +++ b/ziguard.awk @@ -38,6 +38,8 @@ BEGIN { frac["7:07:12"] = "7:07:12.5" # Asia/Jakarta before 1923 frac["7:36:42"] = "7:36:41.7" # Asia/Hong_Kong before 1904 frac["8:05:43"] = "8:05:43.2" # Asia/Shanghai before 1901 + + fract["23:47:12"] = "23:47:12.5" # Asia/Jakarta 1923-12-31 transition } /^Zone/ { zone = $2 } @@ -61,7 +63,7 @@ outfile != "main.zi" { } } - # Add or remove fractional seconds as needed. + # Add or remove fractional seconds as needed in UT offsets. f = $1 == "Zone" ? 3 : 1 for (rounded in frac) { original = frac[rounded] @@ -69,6 +71,13 @@ outfile != "main.zi" { $f = vanguard ? original : rounded } } + # Likewise for transition times. + for (rounded in fract) { + original = fract[rounded] + if ($(f + 6) == rounded || $(f + 6) == original) { + $(f + 6) = vanguard ? original : rounded + } + } } # If a Link line is followed by a Zone line for the same data, comment -- 2.14.3

1 0

[PROPOSED] Generalize data format upgrade procedure
by Paul Eggert Feb. 5, 2018

Feb. 5, 2018

* Makefile (XDST): Remove, replacing with the more-general ... (DATAFORM): ... new macro. All uses changed. (fulldata.zi, pdstdata.zi): Remove, replacing with the more-general ... (vanguard.zi, main.zi, rearguard.zi): ... new targets. All uses changed. (check_zishrink): Fix bug that caused this test to fail when PACKRATDATA was nonempty and testing vanguard or rearguard data. * NEWS, europe: Mention changes. * ziguard.awk: Handle fractional seconds as well as negative DST offsets. Rename from zidst.awk, since it now handles issues other than just DST. All uses changed. --- Makefile | 69 ++++++++++++++++++----------------------------- NEWS | 64 ++++++++++++++++++++++++++------------------ europe | 29 +++++++++----------- zidst.awk | 50 ---------------------------------- ziguard.awk | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 166 insertions(+), 135 deletions(-) delete mode 100644 zidst.awk create mode 100644 ziguard.awk diff --git a/Makefile b/Makefile index 92ddb80..659a5b0 100644 --- a/Makefile +++ b/Makefile @@ -10,25 +10,14 @@ VERSION= unknown # Email address for bug reports. BUGEMAIL= tz(a)iana.org -# To install the full data, which can contain daylight saving time -# offsets that are negative (relative to standard time), use -# XDST= full -# To install data containing only positive daylight saving time -# offsets, but otherwise as close to the full data as practical, use -# XDST= pdst -XDST= pdst -# Parsers requiring DST offsets to be positive should use the file -# pdstdata.zi, which contains almost all the data of 'africa' etc., -# except with positive DST offsets. This works around a problem that -# was discovered in January 2018 with negative DST in tests for ICU -# and OpenJDK. See: -# https://mm.icann.org/pipermail/tz/2018-January/025825.html -# https://mm.icann.org/pipermail/tz/2018-January/025822.html -# Currently the 'africa' etc. files use pdst form if comments are -# ignored, to ease transition for parsers that do not support -# negative DST offsets. This is intended to change to full form at -# some point, so that full-featured zi parsers that use the 'africa' -# files will get the full data without changing anything. +# Choose source data features. To get new features right away, use: +# DATAFORM= vanguard +# To wait a while before using new features, to give downstream users +# time to upgrade zic (the default), use: +# DATAFORM= main +# To wait even longer for new features, use: +# DATAFORM= rearguard +DATAFORM= main # Change the line below for your time zone (after finding the zone you want in # the time zone files, or adding it to a time zone file). @@ -483,8 +472,8 @@ TDATA= $(YDATA) $(NDATA) $(BACKWARD) ZONETABLES= zone1970.tab zone.tab TABDATA= iso3166.tab $(TZDATA_TEXT) $(ZONETABLES) LEAP_DEPS= leapseconds.awk leap-seconds.list -TZDATA_ZI_DEPS= zidst.awk zishrink.awk version $(TDATA) $(PACKRATDATA) -DSTDATA_ZI_DEPS= zidst.awk $(TDATA) $(PACKRATDATA) +TZDATA_ZI_DEPS= ziguard.awk zishrink.awk version $(TDATA) $(PACKRATDATA) +DSTDATA_ZI_DEPS= ziguard.awk $(TDATA) $(PACKRATDATA) DATA= $(TDATA_TO_CHECK) backzone iso3166.tab leap-seconds.list \ leapseconds yearistype.sh $(ZONETABLES) AWK_SCRIPTS= checklinks.awk checktab.awk leapseconds.awk zishrink.awk @@ -522,7 +511,7 @@ VERSION_DEPS= \ SHELL= /bin/sh all: tzselect yearistype zic zdump libtz.a $(TABDATA) \ - fulldata.zi pdstdata.zi + vanguard.zi main.zi rearguard.zi ALL: all date $(ENCHILADA) @@ -558,14 +547,14 @@ version: $(VERSION_DEPS) mv $@.out $@ # These files can be tailored by setting BACKWARD, PACKRATDATA, etc. -fulldata.zi pdstdata.zi: $(DSTDATA_ZI_DEPS) - $(AWK) -v outfile='$@' -f zidst.awk $(TDATA) $(PACKRATDATA) \ +vanguard.zi main.zi rearguard.zi: $(DSTDATA_ZI_DEPS) + $(AWK) -v outfile='$@' -f ziguard.awk $(TDATA) $(PACKRATDATA) \ >$@.out mv $@.out $@ -tzdata.zi: $(XDST)data.zi version +tzdata.zi: $(DATAFORM).zi version version=`sed 1q version` && \ LC_ALL=C $(AWK) -v version="$$version" -f zishrink.awk \ - $(XDST)data.zi >$@.out + $(DATAFORM).zi >$@.out mv $@.out $@ version.h: version @@ -747,31 +736,25 @@ check_tzs: $(TZS) $(TZS_NEW) check_web: tz-how-to.html $(VALIDATE_ENV) $(VALIDATE) $(VALIDATE_FLAGS) tz-how-to.html -# The format of the source files, either full or pdst. -# Currently they are in pdst format, but this is expected to change. -SDST = pdst - -# Check that zishrink.awk does not alter the data, and that zidst.awk -# preserves $(SDST) data. +# Check that zishrink.awk does not alter the data, and that ziguard.awk +# preserves main-format data. check_zishrink: zic leapseconds $(PACKRATDATA) $(TDATA) \ - $(XDST)data.zi tzdata.zi + $(DATAFORM).zi tzdata.zi for type in posix right; do \ - mkdir -p time_t.dir/$$type time_t.dir/$$type-$(SDST) \ + mkdir -p time_t.dir/$$type time_t.dir/$$type-t \ time_t.dir/$$type-shrunk && \ case $$type in \ right) leap='-L leapseconds';; \ *) leap=;; \ esac && \ - $(ZIC) $$leap -d time_t.dir/$$type $(XDST)data.zi && \ - $(AWK) '/^Rule/' $(XDST)data.zi | \ - $(ZIC) $$leap -d time_t.dir/$$type - $(PACKRATDATA) && \ - case $(XDST) in \ - $(SDST)) \ - $(ZIC) $$leap -d time_t.dir/$$type-$(SDST) $(TDATA) && \ + $(ZIC) $$leap -d time_t.dir/$$type $(DATAFORM).zi && \ + case $(DATAFORM) in \ + main) \ + $(ZIC) $$leap -d time_t.dir/$$type-t $(TDATA) && \ $(AWK) '/^Rule/' $(TDATA) | \ - $(ZIC) $$leap -d time_t.dir/$$type-$(SDST) \ - $(XDST)data.zi && \ - diff -r time_t.dir/$$type time_t.dir/$$type-$(SDST);; \ + $(ZIC) $$leap -d time_t.dir/$$type-t - \ + $(PACKRATDATA) && \ + diff -r time_t.dir/$$type time_t.dir/$$type-t;; \ esac && \ $(ZIC) $$leap -d time_t.dir/$$type-shrunk tzdata.zi && \ diff -r time_t.dir/$$type time_t.dir/$$type-shrunk || exit; \ diff --git a/NEWS b/NEWS index adc9814..b13c356 100644 --- a/NEWS +++ b/NEWS @@ -3,8 +3,8 @@ News for the tz database Unreleased, experimental changes Briefly: - Support zi parsers that mishandle negative DST offsets - Add fractional seconds to source data format. + Add support for vanguard and rearguard data consumers. + Add fractional seconds to source data format and to vanguard data. Changes to past time stamps @@ -16,30 +16,41 @@ Unreleased, experimental changes Changes to build procedure - The new XDST macro in the Makefile lets the installer choose - XDST=full, which allows arbitrary DST offsets in the data, or - XDST=pdst, which allows only positive DST offsets. Choosing - XDST=full is arguably more correct for Ireland, which observes - Irish Standard Time (IST, UTC+01) in summer and GMT (UTC) in - winter. Choosing XDST=pdst is better for zoneinfo parsers that do - not work well with negative DST offsets, notably OpenJDK+CLDR. - On platforms using tzcode or similar APIs, XDST should not affect - any behavior other than that depending on the tm_isdst flag. - - For now this change does not affect client-visible behavior by - default, as the Makefile defaults to XDST=pdst and uncommented - parts of the data source files contain only pdst-format data. - After a bit of time for testing, XDST=full and full-format source - files are planned to become the default, so that parsers that - support negative DST offsets can get full data without changing - their build procedures. Parsers requiring positive DST offsets - should use the new file pdstdata.zi instead of tzdata.zi or the - source files 'africa' etc.: pdstdata.zi is pdst-compatible, it is - automatically built from the data source files, and it will - continue to be pdst-compatible regardless of XDST. To get - full-format data now, use the new file fulldata.zi, which will - continue to be full-format regardless of XDST. To get the format - selected by XDST, use tzdata.zi. + The new DATAFORM macro in the Makefile lets the installer choose + among three source data formats. The idea is to lessen downstream + disruption when data formats are improved. + + * DATAFORM=vanguard installs from the latest, bleeding-edge + format. DATAFORM=main (the default) installs from the format + used in the 'africa' etc. files. DATAFORM=rearguard installs + from a trailing-edge format. Eventually, elements of today's + vanguard format should move to the main format, and similarly + the main format's features should eventually move to the + rearguard format. + + * In the current version, the main and rearguard formats are + identical and match that of 2018c, so this change does not + affect default behavior. The vanguard format contains two + features not in the main format: fractional seconds and negative + DST offsets. Fractional seconds were added in this release, + where they affect only zic input (output is unaffected). + Negative DST offsets improve support for Ireland, which uses + Irish Standard Time (IST, UTC+01) in summer and GMT (UTC) in + winter. tzcode has supported negative DST offsets for decades, + and this feature should move to the main format soon. However, + it will not move to the rearguard format for quite some time + because some downstream parsers do not support it. + + * The build procedure constructs three files vanguard.zi, main.zi, + and rearguard.zi, one for each format. The files represent the + same data as closely as the formats allow. These three files + are intended for downstream data consumers and are not + installed. Zoneinfo parsers that require positive DST offsets + should start using rearguard.zi, so that they will be unaffected + when the negative-DST feature moves from vanguard to main. + Bleeding-edge Zoneinfo parsers that support the new features + already can use vanguard.zi; in this respect, current tzcode is + bleeding-edge. Changes to code @@ -48,6 +59,7 @@ Unreleased, experimental changes zic currently rounds these fractions to the nearest integer (breaking ties to the even integer), the fractions may be useful to applications requiring more precision in historical timestamps. + This extension is currently used only in vanguard.zi. The code is a bit more portable to MS-Windows. (Thanks to Manuela Friedrich). diff --git a/europe b/europe index 76cbb5d..8aab26e 100644 --- a/europe +++ b/europe @@ -514,21 +514,19 @@ Link Europe/London Europe/Isle_of_Man # https://mm.icann.org/pipermail/tz/2018-January/025825.html # and with tests for OpenJDK: # https://mm.icann.org/pipermail/tz/2018-January/025822.html -# To work around this problem, zidst.awk translates the following data -# lines into two forms. First, fulldata.zi contains the full data, -# which includes negative DST offsets. Second, pdstdata.zi uses a -# traditional approximation for Irish time stamps after 1971-10-31 -# 02:00 UTC; although this approximation has tm_isdst flags that are -# the reverse of the full data, its UTC offsets are correct and this -# suffices for ICU and OpenJDK. Although this source file currently -# has pdstdata.zi lines active and fulldata.zi lines commented out, -# this is intended to change in the near future and downstream code -# should not rely on it. +# +# To work around this problem, the build procedure can translate the +# following data into two forms, one with negative DST offsets and the +# other form with a traditional approximation for Irish time stamps +# after 1971-10-31 02:00 UTC; although this approximation has tm_isdst +# flags that are reversed, its UTC offsets are correct and this often +# suffices. This source file currently uses only positive DST +# offsets, but this is intended to change and downstream code should +# not rely on it. # # The following is like GB-Eire and EU, except with standard time in -# summer and negative daylight saving time in winter. -# This rule set is active in fulldata.zi and is commented out in -# pdstdata.zi. +# summer and negative daylight saving time in winter. It is for when +# negative DST offsets are used. # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S #Rule Eire 1971 only - Oct 31 2:00u -1:00 GMT #Rule Eire 1972 1980 - Mar Sun>=16 2:00u 0 IST @@ -549,10 +547,9 @@ Zone Europe/Dublin -0:25:00 - LMT 1880 Aug 2 0:00 1:00 IST 1947 Nov 2 2:00s 0:00 - GMT 1948 Apr 18 2:00s 0:00 GB-Eire GMT/IST 1968 Oct 27 -# The next line is active in fulldata.zi and commented out in pdstdata.zi. +# The next line is for when negative DST offsets are used. # 1:00 Eire IST/GMT -# These three lines are active in pdstdata.zi and commented out in -# fulldata.zi. +# These three lines are for when positive DST offsets are used. 1:00 - IST 1971 Oct 31 2:00u 0:00 GB-Eire GMT/IST 1996 0:00 EU GMT/IST diff --git a/zidst.awk b/zidst.awk deleted file mode 100644 index 7885e9a..0000000 --- a/zidst.awk +++ /dev/null @@ -1,50 +0,0 @@ -# Convert tzdata source into full or positive-DST form - -# Contributed by Paul Eggert. This file is in the public domain. - -# This is not a general-purpose converter; it is designed for current tzdata. -# -# When converting to full form, the output can use negative DST offsets. -# -# When converting to positive-DST form, the output uses only positive -# DST offsets. The idea is for the output data to simulate the -# behavior of the input data as best it can within the constraints of -# positive DST offsets. -# -# In the input, lines requiring the full format are commented #[full] -# and the positive DST near-equivalents are commented #[pdst]. - -BEGIN { - dst_type["full"] = 1 - dst_type["pdst"] = 1 - - # The command line should set OUTFILE to the name of the output file, - # which should start with either "full" or "pdst". - todst = substr(outfile, 1, 4) - if (!dst_type[todst]) exit 1 -} - -/^Zone/ { zone = $2 } - -{ - in_comment = /^#/ - - # Test whether this line should differ between the full and the pdst versions. - Rule_Eire = /^#?Rule[\t ]+Eire[\t ]/ - Zone_Dublin_post_1968 \ - = (zone == "Europe/Dublin" && /^#?[\t ]+[01]:00[\t ]/ \ - && (!$(in_comment + 4) || 1968 < $(in_comment + 4))) - - # If so, uncomment the desired version and comment out the undesired one. - if (Rule_Eire || Zone_Dublin_post_1968) { - if ((Rule_Eire \ - || (Zone_Dublin_post_1968 && $(in_comment + 3) == "IST/GMT")) \ - == (todst == "full")) { - sub(/^#/, "") - } else if (/^[^#]/) { - sub(/^/, "#") - } - } -} - -{ print } diff --git a/ziguard.awk b/ziguard.awk new file mode 100644 index 0000000..795b4ef --- /dev/null +++ b/ziguard.awk @@ -0,0 +1,89 @@ +# Convert tzdata source into vanguard or rearguard form. + +# Contributed by Paul Eggert. This file is in the public domain. + +# This is not a general-purpose converter; it is designed for current tzdata. +# +# When converting to vanguard form, the output can use fractional seconds +# and negative DST offsets. +# +# When converting to rearguard form, the output omits fractional +# seconds and uses only positive DST offsets. The idea is for the +# output data to simulate the behavior of the input data as best it +# can within the constraints of the rearguard format. + +BEGIN { + dst_type["vanguard.zi"] = 1 + dst_type["main.zi"] = 1 + dst_type["rearguard.zi"] = 1 + + # The command line should set OUTFILE to the name of the output file. + if (!dst_type[outfile]) exit 1 + vanguard = outfile == "vanguard.zi" + + # List non-integer standard times more accurately if known. + # This list does not attempt to record every UT offset that is + # not an integral multiple of 1 s; it merely records those that + # do not appear to be just LMT. + frac["-5:36:13"] = "-5:36:13.3" # America/Costa_Rica before 1921 + frac["-5:07:10"] = "-5:07:10.41" # America/Jamaica before 1912 + frac["-4:16:48"] = "-4:16:48.25" # America/Cordoba etc. 1894-1920 + frac["-0:36:45"] = "-0:36:44.68" # Europe/Lisbon before 1912 + frac["-0:25:21"] = "-0:25:21.1" # Europe/Dublin 1880-1916 + frac["0:19:32"] = "0:19:32.13" # Europe/Amsterdam before 1937 + frac["1:39:49"] = "1:39:49.2" # Europe/Helsinki before 1921 + frac["2:05:09"] = "2:05:08.9" # Africa/Cairo before 1900 + frac["4:37:11"] = "4:37:10.8" # Asia/Tashkent before 1924 + frac["7:06:30"] = "7:06:30.1333" #... Asia/Ho_Chi_Minh 1906-1911 + frac["7:07:12"] = "7:07:12.5" # Asia/Jakarta before 1923 + frac["7:36:42"] = "7:36:41.7" # Asia/Hong_Kong before 1904 + frac["8:05:43"] = "8:05:43.2" # Asia/Shanghai before 1901 +} + +/^Zone/ { zone = $2 } + +outfile != "main.zi" { + in_comment = /^#/ + + # If this line should differ due to Ireland using negative DST offsets, + # uncomment the desired version and comment out the undesired one. + Rule_Eire = /^#?Rule[\t ]+Eire[\t ]/ + Zone_Dublin_post_1968 \ + = (zone == "Europe/Dublin" && /^#?[\t ]+[01]:00[\t ]/ \ + && (!$(in_comment + 4) || 1968 < $(in_comment + 4))) + if (Rule_Eire || Zone_Dublin_post_1968) { + if ((Rule_Eire \ + || (Zone_Dublin_post_1968 && $(in_comment + 3) == "IST/GMT")) \ + == vanguard) { + sub(/^#/, "") + } else if (/^[^#]/) { + sub(/^/, "#") + } + } + + # Add or remove fractional seconds as needed. + f = $1 == "Zone" ? 3 : 1 + for (rounded in frac) { + original = frac[rounded] + if ($f == rounded || $f == original) { + $f = vanguard ? original : rounded + } + } +} + +# If a Link line is followed by a Zone line for the same data, comment +# out the Link line. This can happen if backzone overrides a Link +# with a Zone. +/^Link/ { + linkline[$3] = NR +} +/^Zone/ { + sub(/^Link/, "#Link", line[linkline[$2]]) +} + +{ line[NR] = $0 } + +END { + for (i = 1; i <= NR; i++) + print line[i] +} -- 2.14.3

1 0

[PROPOSED] zic now rounds to even
by Paul Eggert Feb. 5, 2018

Feb. 5, 2018

* NEWS, zic.8: Mention this. * zic.c (gethms): Round to even instead of discarding fractional seconds. --- NEWS | 5 +++-- zic.8 | 4 +++- zic.c | 18 ++++++++++++++---- 3 files changed, 20 insertions(+), 7 deletions(-) diff --git a/NEWS b/NEWS index f00b29f..adc9814 100644 --- a/NEWS +++ b/NEWS @@ -45,8 +45,9 @@ Unreleased, experimental changes zic now accepts fractional seconds in expressions like 00:19:32.13 (the UT offset of the Netherlands from 1835 to 1937). Although - zic currently ignores these fractions, they may be useful to - applications requiring more precision in historical timestamps. + zic currently rounds these fractions to the nearest integer + (breaking ties to the even integer), the fractions may be useful + to applications requiring more precision in historical timestamps. The code is a bit more portable to MS-Windows. (Thanks to Manuela Friedrich). diff --git a/zic.8 b/zic.8 index f1fc8e2..28e4bd6 100644 --- a/zic.8 +++ b/zic.8 @@ -267,8 +267,10 @@ where hour 0 is midnight at the start of the day, and hour 24 is midnight at the end of the day. Although .I zic -currently ignores any fractional seconds, the fractions may be useful +currently rounds fractional seconds to the nearest integer +(breaking ties to the even integer), the fractions may be useful to other applications requiring greater precision. +The source format does not specify any maximum precision. Any of these forms may be followed by the letter .B w if the given time is local diff --git a/zic.c b/zic.c index 4965a10..6ad31f9 100644 --- a/zic.c +++ b/zic.c @@ -1197,7 +1197,8 @@ gethms(char const *string, char const *errstring, bool signable) { zic_t hh; int sign, mm = 0, ss = 0; - char hhx, mmx, ssx, xs; + char hhx, mmx, ssx, xr = '0', xs; + int tenths = 0; bool ok = true; if (string == NULL || *string == '\0') @@ -1209,10 +1210,18 @@ gethms(char const *string, char const *errstring, bool signable) ++string; } else sign = 1; switch (sscanf(string, - "%"SCNdZIC"%c%d%c%d%c%*1d%*[0123456789]%c", - &hh, &hhx, &mm, &mmx, &ss, &ssx, &xs)) { + "%"SCNdZIC"%c%d%c%d%c%1d%*[0]%c%*[0123456789]%c", + &hh, &hhx, &mm, &mmx, &ss, &ssx, &tenths, &xr, &xs)) { default: ok = false; break; - case 6: ok &= ssx == '.'; /* fallthrough */ + case 8: + ok = '0' <= xr && xr <= '9'; + /* fallthrough */ + case 7: + ok &= ssx == '.'; + if (ok && noise) + warning(_("fractional seconds rejected by" + " pre-2018 versions of zic")); + /* fallthrough */ case 5: ok &= mmx == ':'; /* fallthrough */ case 3: ok &= hhx == ':'; /* fallthrough */ case 1: break; @@ -1231,6 +1240,7 @@ gethms(char const *string, char const *errstring, bool signable) error(_("time overflow")); return 0; } + ss += 5 + ((ss ^ 1) & (xr == '0')) <= tenths; /* Round to even. */ if (noise && (hh > HOURSPERDAY || (hh == HOURSPERDAY && (mm != 0 || ss != 0)))) warning(_("values over 24 hours not handled by pre-2007 versions of zic")); -- 2.7.4

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[PROPOSED] Fix off-by-1 error for Jamaica and T&C before 1913
by Paul Eggert Feb. 5, 2018

Feb. 5, 2018

This was discovered when checking a not-yet-published version of zic. * NEWS: Mention this. * northamerica (America/Jamaica, America/Grand_Turk): * backzone (America/Cayman): Fix rounding error. --- NEWS | 3 +++ backzone | 2 +- northamerica | 6 +++--- 3 files changed, 7 insertions(+), 4 deletions(-) diff --git a/NEWS b/NEWS index beefd39..f00b29f 100644 --- a/NEWS +++ b/NEWS @@ -11,6 +11,9 @@ Unreleased, experimental changes Enderbury and Kiritimati skipped New Year's Eve 1994, not New Year's day 1995. (Thanks to Kerry Shetline.) + Fix an off-by-1 error for pre-1913 timestamps in Jamaica and in + Turks & Caicos. + Changes to build procedure The new XDST macro in the Makefile lets the installer choose diff --git a/backzone b/backzone index 3006b27..cc724aa 100644 --- a/backzone +++ b/backzone @@ -271,7 +271,7 @@ Zone America/Aruba -4:40:24 - LMT 1912 Feb 12 # Oranjestad # Cayman Is Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown - -5:07:11 - KMT 1912 Feb # Kingston Mean Time + -5:07:10 - KMT 1912 Feb # Kingston Mean Time -5:00 - EST # Canada diff --git a/northamerica b/northamerica index a014126..dabca97 100644 --- a/northamerica +++ b/northamerica @@ -3264,8 +3264,8 @@ Zone America/Tegucigalpa -5:48:52 - LMT 1921 Apr # http://www.jamaicaobserver.com/columns/The-politician-in-all-of-us_17573647 # # Zone NAME GMTOFF RULES FORMAT [UNTIL] -Zone America/Jamaica -5:07:11 - LMT 1890 # Kingston - -5:07:11 - KMT 1912 Feb # Kingston Mean Time +Zone America/Jamaica -5:07:10 - LMT 1890 # Kingston + -5:07:10 - KMT 1912 Feb # Kingston Mean Time -5:00 - EST 1974 -5:00 US E%sT 1984 -5:00 - EST @@ -3415,7 +3415,7 @@ Zone America/Miquelon -3:44:40 - LMT 1911 May 15 # St Pierre # # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone America/Grand_Turk -4:44:32 - LMT 1890 - -5:07:11 - KMT 1912 Feb # Kingston Mean Time + -5:07:10 - KMT 1912 Feb # Kingston Mean Time -5:00 - EST 1979 -5:00 US E%sT 2015 Nov Sun>=1 2:00 -4:00 - AST 2018 Mar 11 3:00 -- 2.14.3

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