[PROPOSED 00/18] tzselect improvements for configuring "from now on"

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[PROPOSED 0/9] Fixes for Casey and...

Paul Eggert

Dec. 19, 2023

7:25 a.m.

For some time I've been meaning to extend tzselect so that users who care only about timestamps from now on can have a smaller set of timezones to choose from, thus simplifying configuration. This patchset does this via a new file zonenow.tab, with contents like zone1970.tab except that zonenow.tab partitions based on timestamps from now on, instead of from 1970 on. The new file's format is still experimental and feedback is welcome. These patches mostly just refactor tzselect, to simplify support for the new feature. The last patch adds the new feature. Paul Eggert (18): More-systematic punctuation in *.tab comments Improve Canadian comments in zone*.tab Open /dev/null less often in tzselect * Makefile: Say that ‘make’ should conform to POSIX. Improve tzselect diagnostics after rejection Don’t set TZ in tzselect Do not use empty RE in tzselect Port to POSIX awk, which prohibits -v newlines tzselect: work around mawk bug with {2,} * tzselect: Improve leading comments. tzselect: clarify translit need tzselect: port to POSIX iconv * NEWS: Improve formatting of tzselect news. tzselect: do not create temporary files * tzselect: Indent more consistently. * tzselect.ksh: Consistently omit ‘;;’ before ‘esac’. * tzselect.ksh: Indent more consistently. New tzselection option ‘now’ Makefile | 34 +- NEWS | 28 +- checknow.awk | 53 +++ checktab.awk | 7 +- tzselect.ksh | 977 ++++++++++++++++++++++++++++----------------------- zone.tab | 24 +- zone1970.tab | 24 +- zonenow.tab | 298 ++++++++++++++++ 8 files changed, 978 insertions(+), 467 deletions(-) create mode 100644 checknow.awk create mode 100644 zonenow.tab -- 2.40.1

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Paul Eggert

December 2023

Philip Paeps

7:30 a.m.

New subject: [PROPOSED 06/18] Don’t set TZ in tzselect

On 2023-12-19 15:25:55 (+0800), Paul Eggert via tz wrote:

...

* tzselect.ksh (tz): Rename this shell variable from TZ, so that invoked commands don’t change behavior merely because tzselect is speculating about what TZ setting the user wants. This is a safety measure for oddball platforms where this might make a difference, as POSIX allows utilities to crash if TZ is bogus.

Do such oddball platforms exist in the wild? To a casual reader, seeing $tz instead of $TZ may be confusing. Should we use $tz_for_date instead of $TZ_for_date for consistency? No objection to this. But it feels like refactoring for the sake of refactoring. Philip -- Philip Paeps Senior Reality Engineer Alternative Enterprises

Paul Eggert

6:14 p.m.

New subject: [PROPOSED 06/18] Don’t set TZ in tzselect

On 2023-12-19 23:30, Philip Paeps wrote:

...

On 2023-12-19 15:25:55 (+0800), Paul Eggert via tz wrote:

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* tzselect.ksh (tz): Rename this shell variable from TZ, so that invoked commands don’t change behavior merely because tzselect is speculating about what TZ setting the user wants. This is a safety measure for oddball platforms where this might make a difference, as POSIX allows utilities to crash if TZ is bogus.

Do such oddball platforms exist in the wild?

Yes, we've seen a report of such a problem with old FreeBSD versions, as well as in old tzcode versions. See, for example: https://mm.icann.org/pipermail/tz/1997-January/009772.html To be honest, though, I had forgotten about these old bug reports. I made the change mostly because it's better to be careful with TZ settings in a utility that's designed to let you choose TZ and that lets you specify the TZ string yourself.

...

To a casual reader, seeing $tz instead of $TZ may be confusing.

Yes, I renamed it that way mostly to avoid indenting changes....

...

Should we use $tz_for_date instead of $TZ_for_date for consistency?

* Makefile (ZONETABLES, VERSION_DEPS): Add zonenow.tab. (CHECK_NOW_TIMESTAMP, CHECK_NOW_FUTURE_YEARS, CHECK_NOW_FUTURE_SECS): New macros. (check_now): New target rule. (check_mild): Depend on it. * NEWS: Mention this new feature. * checknow.awk, zonenow.tab: New files. * checktab.awk: Adjust (i.e., loosen) checks for zonenow.tab. * tzselect.ksh (TZ_ZONETABTYPE_TABLE, TZ_ZONENOW_TABLE): New vars, so that the code can switch back and for easily between zone1970.tab and zonenow.tab. (TZ_ZONE_TABLE): Set to one of those two vars, depending on user. Let users choose ‘now’ if they care only about timestamps from now on. Narrow ‘regions’ based on ‘now’ selection, if possible (which it always is, with the current data). --- Makefile | 31 +++++- NEWS | 11 ++ checknow.awk | 53 +++++++++ checktab.awk | 7 +- tzselect.ksh | 49 +++++++-- zonenow.tab | 298 +++++++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 435 insertions(+), 14 deletions(-) create mode 100644 checknow.awk create mode 100644 zonenow.tab diff --git a/Makefile b/Makefile index a6051531..f473af67 100644 --- a/Makefile +++ b/Makefile @@ -580,7 +580,7 @@ YDATA= $(PRIMARY_YDATA) etcetera NDATA= factory TDATA_TO_CHECK= $(YDATA) $(NDATA) backward TDATA= $(YDATA) $(NDATA) $(BACKWARD) -ZONETABLES= zone1970.tab zone.tab +ZONETABLES= zone.tab zone1970.tab zonenow.tab TABDATA= iso3166.tab $(TZDATA_TEXT) $(ZONETABLES) LEAP_DEPS= leapseconds.awk leap-seconds.list TZDATA_ZI_DEPS= ziguard.awk zishrink.awk version $(TDATA) \ @@ -619,7 +619,7 @@ VERSION_DEPS= \ tzfile.5 tzfile.h tzselect.8 tzselect.ksh \ workman.sh zdump.8 zdump.c zic.8 zic.c \ ziguard.awk zishrink.awk \ - zone.tab zone1970.tab + zone.tab zone1970.tab zonenow.tab all: tzselect zic zdump libtz.a $(TABDATA) \ vanguard.zi main.zi rearguard.zi @@ -825,7 +825,8 @@ tzselect: tzselect.ksh version check: check_back check_mild check_mild: check_character_set check_white_space check_links \ - check_name_lengths check_slashed_abbrs check_sorted \ + check_name_lengths check_now \ + check_slashed_abbrs check_sorted \ check_tables check_web check_ziguard check_zishrink check_tzs check_character_set: $(ENCHILADA) @@ -893,7 +894,29 @@ check_links: checklinks.awk tzdata.zi -f checklinks.awk tzdata.zi touch $@ -check_tables: checktab.awk $(YDATA) backward $(ZONETABLES) +# Check timestamps from now through 28 years from now, to make sure +# that zonenow.tab contains all sequences of planned timestamps, +# without any duplicate sequences. In theory this might require +# 2800 years but that would take a long time to check. +CHECK_NOW_TIMESTAMP = `./date +%s` +CHECK_NOW_FUTURE_YEARS = 28 +CHECK_NOW_FUTURE_SECS = $(CHECK_NOW_FUTURE_YEARS) '*' 366 '*' 24 '*' 60 '*' 60 +check_now: checknow.awk date tzdata.zi zdump zic zone1970.tab zonenow.tab + rm -fr $@.dir + mkdir $@.dir + ./zic -d $@.dir tzdata.zi + now=$(CHECK_NOW_TIMESTAMP) && \ + future=`expr $(CHECK_NOW_FUTURE_SECS) + $$now` && \ + ./zdump -i -t $$now,$$future \ + $$(find $$PWD/$@.dir/????*/ -type f) \ + >$@.dir/zdump.tab + $(AWK) \ + -v zdump_table=$@.dir/zdump.tab \ + -f checknow.awk zonenow.tab + rm -fr $@.dir + touch $@ + +check_tables: checktab.awk $(YDATA) backward zone.tab zone1970.tab for tab in $(ZONETABLES); do \ test "$$tab" = zone.tab && links='$(BACKWARD)' || links=''; \ $(AWK) -f checktab.awk -v zone_table=$$tab $(YDATA) $$links \ diff --git a/NEWS b/NEWS index f2d0bc3c..43070aae 100644 --- a/NEWS +++ b/NEWS @@ -5,6 +5,7 @@ Unreleased, experimental changes Briefly: Ittoqqortoormiit, Greenland changes time zones on 2024-03-31. Code and data fixes for Palestine timestamps starting in 2072. + A new data file zonenow.tab for timestamps starting now. Changes to future timestamps @@ -25,6 +26,13 @@ Unreleased, experimental changes This does not affect UTC offsets, only the tm_isdst flag. (Thanks to Thomas M. Steenholdt.) + New data file + + A new data file zonenow.tab helps configure applications that use + timestamps dated from now on. This simplifies configuration, + since users choose from a smaller Zone set. The file's format is + experimental and subject to change. + Changes to code localtime.c no longer mishandles TZif files that contain a single @@ -32,6 +40,9 @@ Unreleased, experimental changes DST was in effect before the transition too. (Thanks to Alois Treindl for debugging help.) + tzselect now optionally reads zonenow.tab, to simplify when + configuring only for timestamps dated from now on. + tzselect no longer creates temporary files. tzselect no longer mishandles the following: diff --git a/checknow.awk b/checknow.awk new file mode 100644 index 00000000..51ee998f --- /dev/null +++ b/checknow.awk @@ -0,0 +1,53 @@ +# Check zonenow.tab for consistency with primary data. + +# Contributed by Paul Eggert. This file is in the public domain. + +function record_zone(zone, data) { + if (zone) { + zone_data[zone] = data + zones[data] = zones[data] " " zone + } +} + +BEGIN { + while (getline <zdump_table) { + if ($0 ~ /^TZ/) { + record_zone(zone, data) + zone = $0 + sub(/.*\.dir\//, "", zone) + sub(/"/, "", zone) + data = "" + } else if ($0 ~ /./) + data = data $0 "\n" + } + record_zone(zone, data) + FS = "\t" +} + +/^[^#]/ { + zone = $3 + data = zone_data[zone] + if (!data) { + printf "%s: no data\n" + status = 1 + } else { + zone2 = zonenow[data] + if (zone2) { + printf "zones %s and %s identical from now on\n", zone, zone2 + status = 1 + } else + zonenow[data] = zone + } +} + +END { + for (zone in zone_data) { + data = zone_data[zone] + if (!zonenow[data]) { + printf "checknow.tab should have one of:%s\n", zones[data] + zonenow[data] = zone # This suppresses duplicate diagnostics. + status = 1 + } + } + exit status +} diff --git a/checktab.awk b/checktab.awk index 2dbf485f..9a26e465 100644 --- a/checktab.awk +++ b/checktab.awk @@ -83,7 +83,7 @@ BEGIN { cc = cca[i] if (cc2name[cc]) { cc_used[cc]++ - } else { + } else if (! (cc == "XX" && zone_table == "zonenow.tab")) { printf "%s:%d: %s: unknown country code\n", \ zone_table, zone_NR, cc >>"/dev/stderr" status = 1 @@ -110,7 +110,7 @@ BEGIN { used_max_cc = cc } } - if (used_max <= 1 && comments) { + if (used_max <= 1 && comments && zone_table != "zonenow.tab") { printf "%s:%d: unnecessary comment '%s'\n", \ zone_table, i, comments \ >>"/dev/stderr" @@ -149,7 +149,8 @@ $1 ~ /^#/ { next } if ($3 ~ /%/) rulePercentUsed[$2] = 1 } if (tz && tz ~ /\// && tz !~ /^Etc\//) { - if (!tztab[tz] && FILENAME != "backward") { + if (!tztab[tz] && FILENAME != "backward" \ + && zone_table != "zonenow.tab") { printf "%s: no data for '%s'\n", zone_table, tz \ >>"/dev/stderr" status = 1 diff --git a/tzselect.ksh b/tzselect.ksh index f894bb56..70bda9c0 100644 --- a/tzselect.ksh +++ b/tzselect.ksh @@ -196,7 +196,8 @@ read_file() { } } read_file TZ_COUNTRY_TABLE "$TZDIR/iso3166.tab" -read_file TZ_ZONE_TABLE "$TZDIR/$zonetabtype.tab" +read_file TZ_ZONETABTYPE_TABLE "$TZDIR/$zonetabtype.tab" +TZ_ZONENOW_TABLE= newline=' ' @@ -385,6 +386,7 @@ while country_result= region= time= + TZ_ZONE_TABLE=$TZ_ZONETABTYPE_TABLE case $coord in ?*) @@ -393,7 +395,8 @@ while # Ask the user for continent or ocean. - echo >&2 'Please select a continent, ocean, "coord", "TZ", or "time".' + echo >&2 \ + 'Please select a continent, ocean, "coord", "TZ", "time", or "now".' quoted_continents=` $AWK ' @@ -406,10 +409,10 @@ while printf "'\''%s'\''\n", entry } BEGIN { - TZ_ZONE_TABLE = substr(ARGV[1], 2) + TZ_ZONETABTYPE_TABLE = substr(ARGV[1], 2) ARGV[1] = "" FS = "\t" - nlines = split(TZ_ZONE_TABLE, line, /\n/) + nlines = split(TZ_ZONETABTYPE_TABLE, line, /\n/) for (i = 1; i <= nlines; i++) { $0 = line[i] if ($0 ~ /^[^#]/) @@ -421,7 +424,7 @@ while } } } - ' ="$TZ_ZONE_TABLE" | + ' ="$TZ_ZONETABTYPE_TABLE" | sort -u | tr '\n' ' ' echo '' @@ -431,12 +434,19 @@ while doselect '"$quoted_continents"' \ "coord - I want to use geographical coordinates." \ "TZ - I want to specify the timezone using the POSIX TZ format." \ - "time - I know local time already." + "time - I know local time already." \ + "now - Like \"time\", but configure only for timestamps from now on." continent=$select_result case $continent in Americas) continent=America;; *" "*) continent=`expr "$continent" : '\''$[^ ]*$'\''` esac + case $zonetabtype,$continent in + zonenow,*) ;; + *,now) + ${TZ_ZONENOW_TABLE:+:} read_file TZ_ZONENOW_TABLE "$TZDIR/zonenow.tab" + TZ_ZONE_TABLE=$TZ_ZONENOW_TABLE + esac ' esac @@ -529,7 +539,7 @@ while `;; *) case $continent in - time) + now|time) minute_format='%a %b %d %H:%M' old_minute=`TZ=UTC0 date +"$minute_format"` for i in 1 2 3 @@ -609,6 +619,31 @@ while ="$continent_re" ="$TZ_COUNTRY_TABLE" ="$zone_table" | sort -f ` + # If all zone table entries have comments, and there are + # at most 22 entries, asked based on those comments. + # This fits the prompt onto old-fashioned 24-line screens. + regions=` + $AWK ' + BEGIN { + TZ_ZONE_TABLE = substr(ARGV[1], 2) + ARGV[1] = "" + FS = "\t" + nlines = split(TZ_ZONE_TABLE, line, /\n/) + for (i = 1; i <= nlines; i++) { + $0 = line[i] + if ($0 ~ /^[^#]/ && !missing_comment) { + if ($4) + comment[++inlines] = $4 + else + missing_comment = 1 + } + } + if (!missing_comment && inlines <= 22) + for (i = 1; i <= inlines; i++) + print comment[i] + } + ' ="$zone_table" + ` # If there's more than one country, ask the user which one. case $countries in diff --git a/zonenow.tab b/zonenow.tab new file mode 100644 index 00000000..b1c1f332 --- /dev/null +++ b/zonenow.tab @@ -0,0 +1,298 @@ +# tzdb timezone descriptions, for users who do not care about old timestamps +# +# This file is in the public domain. +# +# From Paul Eggert (2023-12-18): +# This file contains a table where each row stands for a timezone +# where civil timestamps are predicted to agree from now on. +# This file is like zone1970.tab (see zone1970.tab's coments), +# but with the following changes: +# +# 1. Each timezone corresponds to a set of clocks that are planned +# to agree from now on. This is a larger set of clocks than in +# zone1970.tab, where each timezone's clocks must agree from 1970 on. +# 2. The first column is irrelevant and ignored. +# 3. The table is sorted in a different way: +# first by standard time UTC offset; +# then, if DST is used, by daylight saving UTC offset; +# then by time zone abbreviation. +# +# The format of this table is experimental, and may change in future versions. +# +# This table is intended as an aid for users, to help them select timezones +# appropriate for their practical needs. It is not intended to take or +# endorse any position on legal or territorial claims. +# +#XX coordinates TZ comments +# +# -11 - SST +XX -1416-17042 Pacific/Pago_Pago Midway; Samoa ("SST") +# +# -11 +XX -1901-16955 Pacific/Niue Niue +# +# -10 - HST +XX +211825-1575130 Pacific/Honolulu Hawaii ("HST") +# +# -10 +XX -1732-14934 Pacific/Tahiti Tahiti; Cook Islands +# +# -10/-09 - HST / HDT (North America DST) +XX +515248-1763929 America/Adak western Aleutians in Alaska ("HST/HDT") +# +# -09:30 +XX -0900-13930 Pacific/Marquesas Marquesas +# +# -09 +XX -2308-13457 Pacific/Gambier Gambier +# +# -09/-08 - AKST/AKDT (North America DST) +XX +611305-1495401 America/Anchorage most of Alaska ("AKST/AKDT") +# +# -08 +XX -2504-13005 Pacific/Pitcairn Pitcairn +# +# -08/-07 - PST/PDT (North America DST) +XX +340308-1181434 America/Los_Angeles Pacific ("PST/PDT") - US & Canada; Mexico near US border +# +# -07 - MST +XX +332654-1120424 America/Phoenix Mountain Standard ("MST") - Arizona; western Mexico; Yukon +# +# -07/-06 - MST/MDT (North America DST) +XX +394421-1045903 America/Denver Mountain ("MST/MDT") - US & Canada; Mexico near US border +# +# -06 +XX -0054-08936 Pacific/Galapagos Galápagos +# +# -06 - CST +XX +1924-09909 America/Mexico_City Central Standard ("CST") - Saskatchewan; central Mexico; Central America +# +# -06/-05 (Chile DST) +XX -2709-10926 Pacific/Easter Easter Island +# +# -06/-05 - CST/CDT (North America DST) +XX +415100-0873900 America/Chicago Central ("CST/CDT") - US & Canada; Mexico near US border +# +# -05 +XX -1203-07703 America/Lima eastern South America +# +# -05 - EST +XX +175805-0764736 America/Jamaica Eastern Standard ("EST") - Caymans; Jamaica; eastern Mexico; Panama +# +# -05/-04 - CST/CDT (Cuba DST) +XX +2308-08222 America/Havana Cuba +# +# -05/-04 - EST/EDT (North America DST) +XX +404251-0740023 America/New_York Eastern ("EST/EDT") - US & Canada +# +# -04 +XX +1030-06656 America/Caracas western South America +# +# -04 - AST +XX +1828-06954 America/Santo_Domingo Atlantic Standard ("AST") - eastern Caribbean +# +# -04/-03 (Chile DST) +XX -3327-07040 America/Santiago most of Chile +# +# -04/-03 (Paraguay DST) +XX -2516-05740 America/Asuncion Paraguay +# +# -04/-03 - AST/ADT (North America DST) +XX +4439-06336 America/Halifax Atlantic ("AST/ADT") - Canada; Bermuda +# +# -03:30/-02:30 - NST/NDT (North America DST) +XX +4734-05243 America/St_Johns Newfoundland ("NST/NDT") +# +# -03 +XX -2332-04637 America/Sao_Paulo eastern South America +# +# -03/-02 (North America DST) +XX +4703-05620 America/Miquelon St Pierre & Miquelon +# +# -02 +XX -0351-03225 America/Noronha Fernando de Noronha; South Georgia +# +# -02/-01 (EU DST) +XX +6411-05144 America/Nuuk most of Greenland +# +# -01 +XX +1455-02331 Atlantic/Cape_Verde Cape Verde +# +# -01/+00 (EU DST) +XX +3744-02540 Atlantic/Azores Azores +# -01/+00 (EU DST) until 2024-03-01; then -02/-01 (EU DST) +XX +7029-02158 America/Scoresbysund Ittoqqortoormiit +# +# +00 - GMT +XX +0519-00402 Africa/Abidjan far western Africa; Iceland ("GMT") +# +# +00/+01 - GMT/BST (EU DST) +XX +513030-0000731 Europe/London United Kingdom ("GMT/BST") +# +# +00/+01 - WET/WEST (EU DST) +XX +3843-00908 Europe/Lisbon western Europe ("WET/WEST") +# +# +00/+01 - Troll DST +XX -720041+0023206 Antarctica/Troll Troll Station in Antarctica +# +# +01 - CET +XX +3647+00303 Africa/Algiers Algeria, Tunisia ("CET") +# +# +01 - WAT +XX +0627+00324 Africa/Lagos western Africa ("WAT") +# +# +01/+00 - IST/GMT (EU DST in reverse) +XX +5320-00615 Europe/Dublin Ireland ("IST/GMT") +# +# +01/+00 - (Morocco DST) +XX +3339-00735 Africa/Casablanca Morocco +# +# +01/+02 - CET/CEST (EU DST) +XX +4852+00220 Europe/Paris central Europe ("CET/CEST") +# +# +02 - CAT +XX -2558+03235 Africa/Maputo central Africa ("CAT") +# +# +02 - EET +XX +3254+01311 Africa/Tripoli Libya; Kaliningrad ("EET") +# +# +02 - SAST +XX -2615+02800 Africa/Johannesburg southern Africa ("SAST") +# +# +02/+03 - EET/EEST (EU DST) +XX +3758+02343 Europe/Athens eastern Europe ("EET/EEST") +# +# +02/+03 - EET/EEST (Egypt DST) +XX +3003+03115 Africa/Cairo Egypt +# +# +02/+03 - EET/EEST (Lebanon DST) +XX +3353+03530 Asia/Beirut Lebanon +# +# +02/+03 - EET/EEST (Moldova DST) +XX +4700+02850 Europe/Chisinau Moldova +# +# +02/+03 - EET/EEST (Palestine DST) +XX +3130+03428 Asia/Gaza Palestine +# +# +02/+03 - IST/IDT (Israel DST) +XX +314650+0351326 Asia/Jerusalem Israel +# +# +03 +XX +4101+02858 Europe/Istanbul Near East; Belarus +# +# +03 - EAT +XX -0117+03649 Africa/Nairobi eastern Africa ("EAT") +# +# +03 - MSK +XX +554521+0373704 Europe/Moscow Moscow ("MSK") +# +# +03:30 +XX +3540+05126 Asia/Tehran Iran +# +# +04 +XX +2518+05518 Asia/Dubai Russia; Caucasus; Persian Gulf; Seychelles; Réunion +# +# +04:30 +XX +3431+06912 Asia/Kabul Afghanistan +# +# +05 +XX +4120+06918 Asia/Tashkent Russia; Tajikistan; Turkmenistan; Uzbekistan; Maldives +# +# +05 - PKT +XX +2452+06703 Asia/Karachi Pakistan ("PKT") +# +# +05:30 +XX +0656+07951 Asia/Colombo Sri Lanka +# +# +05:30 - IST +XX +2232+08822 Asia/Kolkata India ("IST") +# +# +05:45 +XX +2743+08519 Asia/Kathmandu Nepal +# +# +06 +XX +2343+09025 Asia/Dhaka Russia; Kyrgyzstan; Bhutan; Bangladesh; Chagos +# +# +06:30 +XX +1647+09610 Asia/Yangon Myanmar; Cocos +# +# +07 +XX +1345+10031 Asia/Bangkok Russia; Indochina; Christmas Island +# +# +07 - WIB +XX -0610+10648 Asia/Jakarta Indonesia ("WIB") +# +# +08 +XX +0117+10351 Asia/Singapore Russia; Brunei; Malaysia; Singapore +# +# +08 - AWST +XX -3157+11551 Australia/Perth Western Australia ("AWST") +# +# +08 - CST +XX +3114+12128 Asia/Shanghai China ("CST") +# +# +08 - HKT +XX +2217+11409 Asia/Hong_Kong Hong Kong ("HKT") +# +# +08 - PHT +XX +1435+12100 Asia/Manila Philippines ("PHT") +# +# +08 - WITA +XX -0507+11924 Asia/Makassar Indonesia ("WITA") +# +# +08:45 +XX -3143+12852 Australia/Eucla Eucla +# +# +09 +XX +5203+11328 Asia/Chita Russia; Palau; East Timor +# +# +09 - JST +XX +353916+1394441 Asia/Tokyo Japan ("JST") +# +# +09 - KST +XX +3733+12658 Asia/Seoul Korea ("KST") +# +# +09 - WIT +XX -0232+14042 Asia/Jayapura Indonesia ("WIT") +# +# +09:30 - ACST +XX -1228+13050 Australia/Darwin Northern Territory ("ACST") +# +# +09:30/+10:30 - ACST/ACDT (Australia DST) +XX -3455+13835 Australia/Adelaide South Australia ("ACST/ACDT") +# +# +10 +XX +4310+13156 Asia/Vladivostok Russia; Yap; Chuuk; Papua New Guinea; Dumont d'Urville +# +# +10 - AEST +XX -2728+15302 Australia/Brisbane Queensland ("AEST") +# +# +10 - ChST +XX +1328+14445 Pacific/Guam Mariana Islands ("ChST") +# +# +10/+11 - AEST/AEDT (Australia DST) +XX -3352+15113 Australia/Sydney southeast Australia ("AEST/AEDT") +# +# +10:30/+11 +XX -3133+15905 Australia/Lord_Howe Lord Howe Island +# +# +11 +XX -0613+15534 Pacific/Bougainville Russia; Kosrae; Bougainville; Solomons +# +# +11/+12 (Australia DST) +XX -2903+16758 Pacific/Norfolk Norfolk Island +# +# +12 +XX +5301+15839 Asia/Kamchatka Russia; Tuvalu; Fiji; etc. +# +# +12/+13 (New Zealand DST) +XX -3652+17446 Pacific/Auckland New Zealand ("NZST/NZDT") +# +# +12:45/+13:45 (Chatham DST) +XX -4357-17633 Pacific/Chatham Chatham Islands +# +# +13 +XX -210800-1751200 Pacific/Tongatapu Kanton; Tokelau; Samoa (western); Tonga +# +# +14 +XX +0152-15720 Pacific/Kiritimati Kiritimati -- 2.40.1

Tim Parenti

5:41 p.m.

New subject: [PROPOSED 18/18] New tzselection option ‘now’

Fixing up a small typo in the comments. One drawback of this approach is that such lines will need to be merged into the appropriate long-term zonenow entry after the date listed. -- Tim Parenti On Tue, 19 Dec 2023 at 02:30, Paul Eggert via tz <tz@iana.org> wrote:

...

* Makefile (ZONETABLES, VERSION_DEPS): Add zonenow.tab. (CHECK_NOW_TIMESTAMP, CHECK_NOW_FUTURE_YEARS, CHECK_NOW_FUTURE_SECS): New macros. (check_now): New target rule. (check_mild): Depend on it. * NEWS: Mention this new feature. * checknow.awk, zonenow.tab: New files. * checktab.awk: Adjust (i.e., loosen) checks for zonenow.tab. * tzselect.ksh (TZ_ZONETABTYPE_TABLE, TZ_ZONENOW_TABLE): New vars, so that the code can switch back and for easily between zone1970.tab and zonenow.tab. (TZ_ZONE_TABLE): Set to one of those two vars, depending on user. Let users choose ‘now’ if they care only about timestamps from now on. Narrow ‘regions’ based on ‘now’ selection, if possible (which it always is, with the current data). --- Makefile | 31 +++++- NEWS | 11 ++ checknow.awk | 53 +++++++++ checktab.awk | 7 +- tzselect.ksh | 49 +++++++-- zonenow.tab | 298 +++++++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 435 insertions(+), 14 deletions(-) create mode 100644 checknow.awk create mode 100644 zonenow.tab

diff --git a/Makefile b/Makefile index a6051531..f473af67 100644 --- a/Makefile +++ b/Makefile @@ -580,7 +580,7 @@ YDATA= $(PRIMARY_YDATA) etcetera NDATA= factory TDATA_TO_CHECK= $(YDATA) $(NDATA) backward TDATA= $(YDATA) $(NDATA) $(BACKWARD) -ZONETABLES= zone1970.tab zone.tab +ZONETABLES= zone.tab zone1970.tab zonenow.tab TABDATA= iso3166.tab $(TZDATA_TEXT) $(ZONETABLES) LEAP_DEPS= leapseconds.awk leap-seconds.list TZDATA_ZI_DEPS= ziguard.awk zishrink.awk version $(TDATA) \ @@ -619,7 +619,7 @@ VERSION_DEPS= \ tzfile.5 tzfile.h tzselect.8 tzselect.ksh \ workman.sh zdump.8 zdump.c zic.8 zic.c \ ziguard.awk zishrink.awk \ - zone.tab zone1970.tab + zone.tab zone1970.tab zonenow.tab

all: tzselect zic zdump libtz.a $(TABDATA) \ vanguard.zi main.zi rearguard.zi @@ -825,7 +825,8 @@ tzselect: tzselect.ksh version

check: check_back check_mild check_mild: check_character_set check_white_space check_links \ - check_name_lengths check_slashed_abbrs check_sorted \ + check_name_lengths check_now \ + check_slashed_abbrs check_sorted \ check_tables check_web check_ziguard check_zishrink check_tzs

check_character_set: $(ENCHILADA) @@ -893,7 +894,29 @@ check_links: checklinks.awk tzdata.zi -f checklinks.awk tzdata.zi touch $@

-check_tables: checktab.awk $(YDATA) backward $(ZONETABLES) +# Check timestamps from now through 28 years from now, to make sure +# that zonenow.tab contains all sequences of planned timestamps, +# without any duplicate sequences. In theory this might require +# 2800 years but that would take a long time to check. +CHECK_NOW_TIMESTAMP = `./date +%s` +CHECK_NOW_FUTURE_YEARS = 28 +CHECK_NOW_FUTURE_SECS = $(CHECK_NOW_FUTURE_YEARS) '*' 366 '*' 24 '*' 60 '*' 60 +check_now: checknow.awk date tzdata.zi zdump zic zone1970.tab zonenow.tab + rm -fr $@.dir + mkdir $@.dir + ./zic -d $@.dir tzdata.zi + now=$(CHECK_NOW_TIMESTAMP) && \ + future=`expr $(CHECK_NOW_FUTURE_SECS) + $$now` && \ + ./zdump -i -t $$now,$$future \ + $$(find $$PWD/$@.dir/????*/ -type f) \ + >$@.dir/zdump.tab + $(AWK) \ + -v zdump_table=$@.dir/zdump.tab \ + -f checknow.awk zonenow.tab + rm -fr $@.dir + touch $@ + +check_tables: checktab.awk $(YDATA) backward zone.tab zone1970.tab for tab in $(ZONETABLES); do \ test "$$tab" = zone.tab && links='$(BACKWARD)' || links=''; \ $(AWK) -f checktab.awk -v zone_table=$$tab $(YDATA) $$links \ diff --git a/NEWS b/NEWS index f2d0bc3c..43070aae 100644 --- a/NEWS +++ b/NEWS @@ -5,6 +5,7 @@ Unreleased, experimental changes Briefly: Ittoqqortoormiit, Greenland changes time zones on 2024-03-31. Code and data fixes for Palestine timestamps starting in 2072. + A new data file zonenow.tab for timestamps starting now.

Changes to future timestamps

@@ -25,6 +26,13 @@ Unreleased, experimental changes This does not affect UTC offsets, only the tm_isdst flag. (Thanks to Thomas M. Steenholdt.)

+ New data file + + A new data file zonenow.tab helps configure applications that use + timestamps dated from now on. This simplifies configuration, + since users choose from a smaller Zone set. The file's format is + experimental and subject to change. + Changes to code

localtime.c no longer mishandles TZif files that contain a single @@ -32,6 +40,9 @@ Unreleased, experimental changes DST was in effect before the transition too. (Thanks to Alois Treindl for debugging help.)

+ tzselect now optionally reads zonenow.tab, to simplify when + configuring only for timestamps dated from now on. + tzselect no longer creates temporary files.

tzselect no longer mishandles the following: diff --git a/checknow.awk b/checknow.awk new file mode 100644 index 00000000..51ee998f --- /dev/null +++ b/checknow.awk @@ -0,0 +1,53 @@ +# Check zonenow.tab for consistency with primary data. + +# Contributed by Paul Eggert. This file is in the public domain. + +function record_zone(zone, data) { + if (zone) { + zone_data[zone] = data + zones[data] = zones[data] " " zone + } +} + +BEGIN { + while (getline <zdump_table) { + if ($0 ~ /^TZ/) { + record_zone(zone, data) + zone = $0 + sub(/.*\.dir\//, "", zone) + sub(/"/, "", zone) + data = "" + } else if ($0 ~ /./) + data = data $0 "\n" + } + record_zone(zone, data) + FS = "\t" +} + +/^[^#]/ { + zone = $3 + data = zone_data[zone] + if (!data) { + printf "%s: no data\n" + status = 1 + } else { + zone2 = zonenow[data] + if (zone2) { + printf "zones %s and %s identical from now on\n", zone, zone2 + status = 1 + } else + zonenow[data] = zone + } +} + +END { + for (zone in zone_data) { + data = zone_data[zone] + if (!zonenow[data]) { + printf "checknow.tab should have one of:%s\n", zones[data] + zonenow[data] = zone # This suppresses duplicate diagnostics. + status = 1 + } + } + exit status +} diff --git a/checktab.awk b/checktab.awk index 2dbf485f..9a26e465 100644 --- a/checktab.awk +++ b/checktab.awk @@ -83,7 +83,7 @@ BEGIN { cc = cca[i] if (cc2name[cc]) { cc_used[cc]++ - } else { + } else if (! (cc == "XX" && zone_table == "zonenow.tab")) { printf "%s:%d: %s: unknown country code\n", \ zone_table, zone_NR, cc >>"/dev/stderr" status = 1 @@ -110,7 +110,7 @@ BEGIN { used_max_cc = cc } } - if (used_max <= 1 && comments) { + if (used_max <= 1 && comments && zone_table != "zonenow.tab") { printf "%s:%d: unnecessary comment '%s'\n", \ zone_table, i, comments \ >>"/dev/stderr" @@ -149,7 +149,8 @@ $1 ~ /^#/ { next } if ($3 ~ /%/) rulePercentUsed[$2] = 1 } if (tz && tz ~ /\// && tz !~ /^Etc\//) { - if (!tztab[tz] && FILENAME != "backward") { + if (!tztab[tz] && FILENAME != "backward" \ + && zone_table != "zonenow.tab") { printf "%s: no data for '%s'\n", zone_table, tz \ >>"/dev/stderr" status = 1 diff --git a/tzselect.ksh b/tzselect.ksh index f894bb56..70bda9c0 100644 --- a/tzselect.ksh +++ b/tzselect.ksh @@ -196,7 +196,8 @@ read_file() { } } read_file TZ_COUNTRY_TABLE "$TZDIR/iso3166.tab" -read_file TZ_ZONE_TABLE "$TZDIR/$zonetabtype.tab" +read_file TZ_ZONETABTYPE_TABLE "$TZDIR/$zonetabtype.tab" +TZ_ZONENOW_TABLE=

newline=' ' @@ -385,6 +386,7 @@ while country_result= region= time= + TZ_ZONE_TABLE=$TZ_ZONETABTYPE_TABLE

case $coord in ?*) @@ -393,7 +395,8 @@ while

# Ask the user for continent or ocean.

- echo >&2 'Please select a continent, ocean, "coord", "TZ", or "time".' + echo >&2 \ + 'Please select a continent, ocean, "coord", "TZ", "time", or "now".'

quoted_continents=` $AWK ' @@ -406,10 +409,10 @@ while printf "'\''%s'\''\n", entry } BEGIN { - TZ_ZONE_TABLE = substr(ARGV[1], 2) + TZ_ZONETABTYPE_TABLE = substr(ARGV[1], 2) ARGV[1] = "" FS = "\t" - nlines = split(TZ_ZONE_TABLE, line, /\n/) + nlines = split(TZ_ZONETABTYPE_TABLE, line, /\n/) for (i = 1; i <= nlines; i++) { $0 = line[i] if ($0 ~ /^[^#]/) @@ -421,7 +424,7 @@ while } } } - ' ="$TZ_ZONE_TABLE" | + ' ="$TZ_ZONETABTYPE_TABLE" | sort -u | tr '\n' ' ' echo '' @@ -431,12 +434,19 @@ while doselect '"$quoted_continents"' \ "coord - I want to use geographical coordinates." \ "TZ - I want to specify the timezone using the POSIX TZ format." \ - "time - I know local time already." + "time - I know local time already." \ + "now - Like \"time\", but configure only for timestamps from now on." continent=$select_result case $continent in Americas) continent=America;; *" "*) continent=`expr "$continent" : '\''$[^ ]*$'\''` esac + case $zonetabtype,$continent in + zonenow,*) ;; + *,now) + ${TZ_ZONENOW_TABLE:+:} read_file TZ_ZONENOW_TABLE "$TZDIR/zonenow.tab" + TZ_ZONE_TABLE=$TZ_ZONENOW_TABLE + esac ' esac

@@ -529,7 +539,7 @@ while `;; *) case $continent in - time) + now|time) minute_format='%a %b %d %H:%M' old_minute=`TZ=UTC0 date +"$minute_format"` for i in 1 2 3 @@ -609,6 +619,31 @@ while ="$continent_re" ="$TZ_COUNTRY_TABLE" ="$zone_table" | sort -f ` + # If all zone table entries have comments, and there are + # at most 22 entries, asked based on those comments. + # This fits the prompt onto old-fashioned 24-line screens. + regions=` + $AWK ' + BEGIN { + TZ_ZONE_TABLE = substr(ARGV[1], 2) + ARGV[1] = "" + FS = "\t" + nlines = split(TZ_ZONE_TABLE, line, /\n/) + for (i = 1; i <= nlines; i++) { + $0 = line[i] + if ($0 ~ /^[^#]/ && !missing_comment) { + if ($4) + comment[++inlines] = $4 + else + missing_comment = 1 + } + } + if (!missing_comment && inlines <= 22) + for (i = 1; i <= inlines; i++) + print comment[i] + } + ' ="$zone_table" + `

# If there's more than one country, ask the user which one. case $countries in diff --git a/zonenow.tab b/zonenow.tab new file mode 100644 index 00000000..b1c1f332 --- /dev/null +++ b/zonenow.tab @@ -0,0 +1,298 @@ +# tzdb timezone descriptions, for users who do not care about old timestamps +# +# This file is in the public domain. +# +# From Paul Eggert (2023-12-18): +# This file contains a table where each row stands for a timezone +# where civil timestamps are predicted to agree from now on. +# This file is like zone1970.tab (see zone1970.tab's coments), +# but with the following changes: +# +# 1. Each timezone corresponds to a set of clocks that are planned +# to agree from now on. This is a larger set of clocks than in +# zone1970.tab, where each timezone's clocks must agree from 1970 on. +# 2. The first column is irrelevant and ignored. +# 3. The table is sorted in a different way: +# first by standard time UTC offset; +# then, if DST is used, by daylight saving UTC offset; +# then by time zone abbreviation. +# +# The format of this table is experimental, and may change in future versions. +# +# This table is intended as an aid for users, to help them select timezones +# appropriate for their practical needs. It is not intended to take or +# endorse any position on legal or territorial claims. +# +#XX coordinates TZ comments +# +# -11 - SST +XX -1416-17042 Pacific/Pago_Pago Midway; Samoa ("SST") +# +# -11 +XX -1901-16955 Pacific/Niue Niue +# +# -10 - HST +XX +211825-1575130 Pacific/Honolulu Hawaii ("HST") +# +# -10 +XX -1732-14934 Pacific/Tahiti Tahiti; Cook Islands +# +# -10/-09 - HST / HDT (North America DST) +XX +515248-1763929 America/Adak western Aleutians in Alaska ("HST/HDT") +# +# -09:30 +XX -0900-13930 Pacific/Marquesas Marquesas +# +# -09 +XX -2308-13457 Pacific/Gambier Gambier +# +# -09/-08 - AKST/AKDT (North America DST) +XX +611305-1495401 America/Anchorage most of Alaska ("AKST/AKDT") +# +# -08 +XX -2504-13005 Pacific/Pitcairn Pitcairn +# +# -08/-07 - PST/PDT (North America DST) +XX +340308-1181434 America/Los_Angeles Pacific ("PST/PDT") - US & Canada; Mexico near US border +# +# -07 - MST +XX +332654-1120424 America/Phoenix Mountain Standard ("MST") - Arizona; western Mexico; Yukon +# +# -07/-06 - MST/MDT (North America DST) +XX +394421-1045903 America/Denver Mountain ("MST/MDT") - US & Canada; Mexico near US border +# +# -06 +XX -0054-08936 Pacific/Galapagos Galápagos +# +# -06 - CST +XX +1924-09909 America/Mexico_City Central Standard ("CST") - Saskatchewan; central Mexico; Central America +# +# -06/-05 (Chile DST) +XX -2709-10926 Pacific/Easter Easter Island +# +# -06/-05 - CST/CDT (North America DST) +XX +415100-0873900 America/Chicago Central ("CST/CDT") - US & Canada; Mexico near US border +# +# -05 +XX -1203-07703 America/Lima eastern South America +# +# -05 - EST +XX +175805-0764736 America/Jamaica Eastern Standard ("EST") - Caymans; Jamaica; eastern Mexico; Panama +# +# -05/-04 - CST/CDT (Cuba DST) +XX +2308-08222 America/Havana Cuba +# +# -05/-04 - EST/EDT (North America DST) +XX +404251-0740023 America/New_York Eastern ("EST/EDT") - US & Canada +# +# -04 +XX +1030-06656 America/Caracas western South America +# +# -04 - AST +XX +1828-06954 America/Santo_Domingo Atlantic Standard ("AST") - eastern Caribbean +# +# -04/-03 (Chile DST) +XX -3327-07040 America/Santiago most of Chile +# +# -04/-03 (Paraguay DST) +XX -2516-05740 America/Asuncion Paraguay +# +# -04/-03 - AST/ADT (North America DST) +XX +4439-06336 America/Halifax Atlantic ("AST/ADT") - Canada; Bermuda +# +# -03:30/-02:30 - NST/NDT (North America DST) +XX +4734-05243 America/St_Johns Newfoundland ("NST/NDT") +# +# -03 +XX -2332-04637 America/Sao_Paulo eastern South America +# +# -03/-02 (North America DST) +XX +4703-05620 America/Miquelon St Pierre & Miquelon +# +# -02 +XX -0351-03225 America/Noronha Fernando de Noronha; South Georgia +# +# -02/-01 (EU DST) +XX +6411-05144 America/Nuuk most of Greenland +# +# -01 +XX +1455-02331 Atlantic/Cape_Verde Cape Verde +# +# -01/+00 (EU DST) +XX +3744-02540 Atlantic/Azores Azores +# -01/+00 (EU DST) until 2024-03-01; then -02/-01 (EU DST) +XX +7029-02158 America/Scoresbysund Ittoqqortoormiit +# +# +00 - GMT +XX +0519-00402 Africa/Abidjan far western Africa; Iceland ("GMT") +# +# +00/+01 - GMT/BST (EU DST) +XX +513030-0000731 Europe/London United Kingdom ("GMT/BST") +# +# +00/+01 - WET/WEST (EU DST) +XX +3843-00908 Europe/Lisbon western Europe ("WET/WEST") +# +# +00/+01 - Troll DST +XX -720041+0023206 Antarctica/Troll Troll Station in Antarctica +# +# +01 - CET +XX +3647+00303 Africa/Algiers Algeria, Tunisia ("CET") +# +# +01 - WAT +XX +0627+00324 Africa/Lagos western Africa ("WAT") +# +# +01/+00 - IST/GMT (EU DST in reverse) +XX +5320-00615 Europe/Dublin Ireland ("IST/GMT") +# +# +01/+00 - (Morocco DST) +XX +3339-00735 Africa/Casablanca Morocco +# +# +01/+02 - CET/CEST (EU DST) +XX +4852+00220 Europe/Paris central Europe ("CET/CEST") +# +# +02 - CAT +XX -2558+03235 Africa/Maputo central Africa ("CAT") +# +# +02 - EET +XX +3254+01311 Africa/Tripoli Libya; Kaliningrad ("EET") +# +# +02 - SAST +XX -2615+02800 Africa/Johannesburg southern Africa ("SAST") +# +# +02/+03 - EET/EEST (EU DST) +XX +3758+02343 Europe/Athens eastern Europe ("EET/EEST") +# +# +02/+03 - EET/EEST (Egypt DST) +XX +3003+03115 Africa/Cairo Egypt +# +# +02/+03 - EET/EEST (Lebanon DST) +XX +3353+03530 Asia/Beirut Lebanon +# +# +02/+03 - EET/EEST (Moldova DST) +XX +4700+02850 Europe/Chisinau Moldova +# +# +02/+03 - EET/EEST (Palestine DST) +XX +3130+03428 Asia/Gaza Palestine +# +# +02/+03 - IST/IDT (Israel DST) +XX +314650+0351326 Asia/Jerusalem Israel +# +# +03 +XX +4101+02858 Europe/Istanbul Near East; Belarus +# +# +03 - EAT +XX -0117+03649 Africa/Nairobi eastern Africa ("EAT") +# +# +03 - MSK +XX +554521+0373704 Europe/Moscow Moscow ("MSK") +# +# +03:30 +XX +3540+05126 Asia/Tehran Iran +# +# +04 +XX +2518+05518 Asia/Dubai Russia; Caucasus; Persian Gulf; Seychelles; Réunion +# +# +04:30 +XX +3431+06912 Asia/Kabul Afghanistan +# +# +05 +XX +4120+06918 Asia/Tashkent Russia; Tajikistan; Turkmenistan; Uzbekistan; Maldives +# +# +05 - PKT +XX +2452+06703 Asia/Karachi Pakistan ("PKT") +# +# +05:30 +XX +0656+07951 Asia/Colombo Sri Lanka +# +# +05:30 - IST +XX +2232+08822 Asia/Kolkata India ("IST") +# +# +05:45 +XX +2743+08519 Asia/Kathmandu Nepal +# +# +06 +XX +2343+09025 Asia/Dhaka Russia; Kyrgyzstan; Bhutan; Bangladesh; Chagos +# +# +06:30 +XX +1647+09610 Asia/Yangon Myanmar; Cocos +# +# +07 +XX +1345+10031 Asia/Bangkok Russia; Indochina; Christmas Island +# +# +07 - WIB +XX -0610+10648 Asia/Jakarta Indonesia ("WIB") +# +# +08 +XX +0117+10351 Asia/Singapore Russia; Brunei; Malaysia; Singapore +# +# +08 - AWST +XX -3157+11551 Australia/Perth Western Australia ("AWST") +# +# +08 - CST +XX +3114+12128 Asia/Shanghai China ("CST") +# +# +08 - HKT +XX +2217+11409 Asia/Hong_Kong Hong Kong ("HKT") +# +# +08 - PHT +XX +1435+12100 Asia/Manila Philippines ("PHT") +# +# +08 - WITA +XX -0507+11924 Asia/Makassar Indonesia ("WITA") +# +# +08:45 +XX -3143+12852 Australia/Eucla Eucla +# +# +09 +XX +5203+11328 Asia/Chita Russia; Palau; East Timor +# +# +09 - JST +XX +353916+1394441 Asia/Tokyo Japan ("JST") +# +# +09 - KST +XX +3733+12658 Asia/Seoul Korea ("KST") +# +# +09 - WIT +XX -0232+14042 Asia/Jayapura Indonesia ("WIT") +# +# +09:30 - ACST +XX -1228+13050 Australia/Darwin Northern Territory ("ACST") +# +# +09:30/+10:30 - ACST/ACDT (Australia DST) +XX -3455+13835 Australia/Adelaide South Australia ("ACST/ACDT") +# +# +10 +XX +4310+13156 Asia/Vladivostok Russia; Yap; Chuuk; Papua New Guinea; Dumont d'Urville +# +# +10 - AEST +XX -2728+15302 Australia/Brisbane Queensland ("AEST") +# +# +10 - ChST +XX +1328+14445 Pacific/Guam Mariana Islands ("ChST") +# +# +10/+11 - AEST/AEDT (Australia DST) +XX -3352+15113 Australia/Sydney southeast Australia ("AEST/AEDT") +# +# +10:30/+11 +XX -3133+15905 Australia/Lord_Howe Lord Howe Island +# +# +11 +XX -0613+15534 Pacific/Bougainville Russia; Kosrae; Bougainville; Solomons +# +# +11/+12 (Australia DST) +XX -2903+16758 Pacific/Norfolk Norfolk Island +# +# +12 +XX +5301+15839 Asia/Kamchatka Russia; Tuvalu; Fiji; etc. +# +# +12/+13 (New Zealand DST) +XX -3652+17446 Pacific/Auckland New Zealand ("NZST/NZDT") +# +# +12:45/+13:45 (Chatham DST) +XX -4357-17633 Pacific/Chatham Chatham Islands +# +# +13 +XX -210800-1751200 Pacific/Tongatapu Kanton; Tokelau; Samoa (western); Tonga +# +# +14 +XX +0152-15720 Pacific/Kiritimati Kiritimati -- 2.40.1

Paul Eggert

5:59 p.m.

New subject: [PROPOSED 18/18] New tzselection option ‘now’

On 2023-12-20 09:41, Tim Parenti wrote:

...

One drawback of this approach is that such lines will need to be merged into the appropriate long-term zonenow entry after the date listed.

That shouldn't be a problem in this particular case. After the date listed, the comment line and associated data line should simply vanish. There should then be no need to alter the comment line or comments column for the America/Nuuk ("most of Greenland") line, since Ittoqqortoormiit is in "most of Greenland". The main reason there's a comment with a date now, is to remind us to remove the comment and the associated data line then. (This is belt and suspenders as "make check" should also remind us.) You're right that it is an issue in the general case when data lines are removed (or added) in zonenow.tab. That's why zonenow.tab is a separate file. Although I originally wanted to calculate zonenow.tab automatically, there was too much human judgment in its "comments" column. Thanks for catching the typo. I have more typo fixes on the way....

Alfred Finamore

7:57 p.m.

New subject: [PROPOSED 18/18] New tzselection option ‘now’

null On Wed, Dec 20, 2023 at 12:00 PM Paul Eggert via tz <tz@iana.org> wrote:

...

On 2023-12-20 09:41, Tim Parenti wrote:

...
One drawback of this approach is that such lines will need to be merged into the appropriate long-term zonenow entry after the date listed.

That shouldn't be a problem in this particular case. After the date listed, the comment line and associated data line should simply vanish. There should then be no need to alter the comment line or comments column for the America/Nuuk ("most of Greenland") line, since Ittoqqortoormiit is in "most of Greenland".

The main reason there's a comment with a date now, is to remind us to remove the comment and the associated data line then. (This is belt and suspenders as "make check" should also remind us.)

You're right that it is an issue in the general case when data lines are removed (or added) in zonenow.tab. That's why zonenow.tab is a separate file. Although I originally wanted to calculate zonenow.tab automatically, there was too much human judgment in its "comments" column.

Thanks for catching the typo. I have more typo fixes on the way....

Philip Paeps

7:51 a.m.

New subject: [PROPOSED 00/18] tzselect improvements for configuring "from now on"

On 2023-12-19 15:25:49 (+0800), Paul Eggert via tz wrote:

...

For some time I've been meaning to extend tzselect so that users who care only about timestamps from now on can have a smaller set of timezones to choose from, thus simplifying configuration.

This patchset does this via a new file zonenow.tab, with contents like zone1970.tab except that zonenow.tab partitions based on timestamps from now on, instead of from 1970 on. The new file's format is still experimental and feedback is welcome.

These patches mostly just refactor tzselect, to simplify support for the new feature. The last patch adds the new feature.

I skimmed through all the patches in this set. Other than the minor comment I made about refactoring for the sake of refactoring, the diffs look good to me. I'll try to find a chance to test this on FreeBSD in the coming days. Philip -- Philip Paeps Senior Reality Engineer Alternative Enterprises

Paul Eggert

1:36 a.m.

New subject: [PROPOSED 00/18] tzselect improvements for configuring "from now on"

On 2023-12-19 23:51, Philip Paeps wrote:

...

I'll try to find a chance to test this on FreeBSD in the coming days.

Thanks for the quick review. Your email inspired me to run 'make check' on FreeBSD 14 and I found a false positive from FreeBSD's C compiler suite: FreeBSD 14's c99 command incorrectly diagnoses uses of _Generic even when the uses are protected by "#if __has_extension(c_generic_selections)". I installed this patch to work around the problem: https://github.com/eggert/tz/commit/ce293ccb574a77956c758a81287dbc8ef4f4eedf along with some other patches I just now emailed to the list. This is by no means a full set of tests on FreeBSD, so any further testing you can do would be appreciated, even if the testing is after the next TZDB release is published.

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Alfred Finamore
Paul Eggert
Philip Paeps
Tim Parenti

[PROPOSED 00/18] tzselect improvements for configuring "from now on"

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