December 2024 - tz - lists.iana.org

How permanent daylight saving time or permanent standard time would affect the USA
by Jonathan Leffler Dec. 13, 2024

Dec. 13, 2024

Article in the Washington Post about how early or late you would be in the dark if the USA adopted permanent daylight saving time or permanent standard time (compared with now). https://www.washingtonpost.com/nation/interactive/2024/no-daylight-saving-t… With decent interactive graphics. I'm a subscriber; I don't know if there's a paywall in place. -- Jonathan Leffler <jonathan.leffler(a)gmail.com> #include <disclaimer.h> Guardian of DBD::Informix - v2018.1031 - http://dbi.perl.org "Blessed are we who can laugh at ourselves, for we shall never cease to be amused."

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[PROPOSED] Fix asctime.o, strftime.o dependencies
by Paul Eggert Dec. 12, 2024

Dec. 12, 2024

* Makefile (asctime.o): Don’t depend on tzfile.h. (strftime.o): Depend on tzdir.h, as it’s included indirectly via localtime.c if MKTIME_MIGHT_OVERFLOW. --- Makefile | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/Makefile b/Makefile index 2aafdc24..8faab6ff 100644 --- a/Makefile +++ b/Makefile @@ -1355,11 +1355,11 @@ long-long.ck unsigned.ck: $(VERSION_DEPS) zonenames: tzdata.zi @$(AWK) '/^Z/ { print $$2 } /^L/ { print $$3 }' tzdata.zi -asctime.o: private.h tzfile.h +asctime.o: private.h date.o: private.h difftime.o: private.h -localtime.o: private.h tzfile.h tzdir.h -strftime.o: localtime.c private.h tzfile.h +localtime.o: private.h tzdir.h tzfile.h +strftime.o: localtime.c private.h tzdir.h tzfile.h zdump.o: version.h zic.o: private.h tzfile.h tzdir.h version.h -- 2.47.1

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[PROPOSED] Fix to2050.tzs timestamp in distributed tarball
by Paul Eggert Dec. 12, 2024

Dec. 12, 2024

* Makefile (TZS_DEPS): Remove asctime.c and add localtime.c. --- Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 5473dedd..2aafdc24 100644 --- a/Makefile +++ b/Makefile @@ -615,8 +615,8 @@ TZS_YEAR= 2050 TZS_CUTOFF_FLAG= -c $(TZS_YEAR) TZS= to$(TZS_YEAR).tzs TZS_NEW= to$(TZS_YEAR)new.tzs -TZS_DEPS= $(YDATA) asctime.c localtime.c \ - private.h tzfile.h zdump.c zic.c +TZS_DEPS= $(YDATA) localtime.c private.h \ + strftime.c tzfile.h zdump.c zic.c TZDATA_DIST = $(COMMON) $(DATA) $(MISC) # EIGHT_YARDS is just a yard short of the whole ENCHILADA. EIGHT_YARDS = $(TZDATA_DIST) $(DOCS) $(SOURCES) tzdata.zi -- 2.47.1

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Add ICU's Etc/Unknown Zone to IANA Time Zone Database?
by Justin Grant Dec. 11, 2024

Dec. 11, 2024

Hi TZ friends - Should the time zone identifier "Etc/Unknown" (standardized in Unicode Technical Standard 35 and used by the ICU <https://icu.unicode.org/> library that implements time zone support in all major web browsers, in Java, and in other platforms) be added to the IANA Time Zone Database? Etc/Unknown would behave the same as the existing time zone identifier "Factory". Ideally, Etc/Unknown could be a Zone and Factory could be turned into a Link pointing to Etc/Unknown, because both of them have the meaning of "the time zone of this computer is not known" but Etc/Unknown is more self-describing and is better aligned with modern Zone naming conventions. Here's more context: "Etc/Unknown" is standardized in https://unicode.org/reports/tr35/#Time_Zone_Identifiers. Here's the relevant text from the standard: > There is a special code "unk" for an Unknown or Invalid time zone. > This can be expressed in the tz database style ID "Etc/Unknown", > although it is not defined in the tz database. Following this standard, Etc/Unknown is returned by ICU <https://icu.unicode.org/> when the time zone of a computer cannot be determined. Here's an example of an ICU method that can return Etc/Unknown: icu::TimeZone::detectHostTimeZone() <https://unicode-org.github.io/icu-docs/apidoc/dev/icu4c/classicu_1_1TimeZon…> . The fact that Etc/Unknown looks like an IANA identifier but is not actually in TZDB has been a long-running source of problems. Most recently, this week Chrome is rushing out a patch <https://issues.chromium.org/issues/381620359> that reverted a recent change that added support for the "Factory" zone by making it an alias for "Etc/Unknown". GIven that ICU previously didn't recognize Factory and so returned Etc/Unknown for computers in the Factory zone, this was assumed by everyone to be a safe change. But this change turned out to break some 3rd-party libraries and had to be reverted. After discussing this recent bug with engineers at Google, our consensus was that it'd be helpful for the time zone ecosystem if Etc/Unknown stopped being a special case and started being a regular Zone in the IANA Time Zone database. Especially if we could Link-ify Factory at the same time so that Zone picker UIs won't have two distinct "I don't know what time zone this is" choices. Thanks for considering this proposal. Best, Justin Grant

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[PROPOSED] Fix unlikely multithreaded file descriptor leak
by Paul Eggert Dec. 9, 2024

Dec. 9, 2024

On multithreaded platforms, tzset could leak a file descriptor into a forked or execed process. Fix the leak. While we’re at it, don’t let the TZif file become the controlling tty. * NEWS: Mention this. * localtime.c (O_CLOEXEC, O_CLOFORK, O_IGNORE_CTTY, O_NOCTTY): Default to 0. (tzloadbody): Use these flags when opening the TZif file. --- NEWS | 5 +++++ localtime.c | 22 +++++++++++++++++----- 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/NEWS b/NEWS index 79686147..2fc7bb19 100644 --- a/NEWS +++ b/NEWS @@ -56,6 +56,11 @@ Unreleased, experimental changes PTRDIFF_MAX, a limit forced by C anyway; formerly tzcode silently misbehaved unless TZNAME_MAXIMUM was less than INT_MAX. + tzset and related functions no longer leak a file descriptor if + another thread forks or execs at about the same time and if the + platform has O_CLOFORK and O_CLOEXEC respectively. Also, the + functions no longer let a TZif file become a controlling terminal. + Changes to documentation The name Etc/Unknown is now reserved: it will not be used by TZDB. diff --git a/localtime.c b/localtime.c index 492965d9..f92676c6 100644 --- a/localtime.c +++ b/localtime.c @@ -96,12 +96,23 @@ typedef intmax_t timex_t; # define TZ_ABBR_ERR_CHAR '_' #endif /* !defined TZ_ABBR_ERR_CHAR */ -/* -** Support non-POSIX platforms that distinguish between text and binary files. -*/ +/* Port to platforms that lack some O_* flags. Unless otherwise + specified, the flags are standardized by POSIX. */ #ifndef O_BINARY -# define O_BINARY 0 +# define O_BINARY 0 /* MS-Windows */ +#endif +#ifndef O_CLOEXEC +# define O_CLOEXEC 0 +#endif +#ifndef O_CLOFORK +# define O_CLOFORK 0 +#endif +#ifndef O_IGNORE_CTTY +# define O_IGNORE_CTTY 0 /* GNU/Hurd */ +#endif +#ifndef O_NOCTTY +# define O_NOCTTY 0 #endif #ifndef WILDABBR @@ -542,7 +553,8 @@ tzloadbody(char const *name, struct state *sp, bool doextend, } if (doaccess && access(name, R_OK) != 0) return errno; - fid = open(name, O_RDONLY | O_BINARY); + fid = open(name, (O_RDONLY | O_BINARY | O_CLOEXEC | O_CLOFORK + | O_IGNORE_CTTY | O_NOCTTY)); if (fid < 0) return errno; -- 2.47.0

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US Department of Transportation map of US timezones
by Roozbeh Pournader Dec. 7, 2024

Dec. 7, 2024

I just found out through https://x.com/RedistrictNet/status/1863742503242875046 That the US Department of Transportation has just rolled out an official map of US timezones. It's supposed to be at: https://geodata.bts.gov/datasets/usdot::time-zones/about (It doesn't load for me at the moment, possibly due to high demand.) Roozbeh

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[PROPOSED] Fix checknow confusing diagnostics
by Paul Eggert Dec. 7, 2024

Dec. 7, 2024

* checknow.awk: Do not report a duplicate (and confusing) diagnostic when a zone has no data. --- checknow.awk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/checknow.awk b/checknow.awk index 8b7881d2..450490ee 100644 --- a/checknow.awk +++ b/checknow.awk @@ -44,7 +44,7 @@ BEGIN { END { for (zone in zone_data) { data = zone_data[zone] - if (!zonenow[data]) { + if (data && !zonenow[data]) { printf "Zone table should have one of:%s\n", zones[data] zonenow[data] = zone # This suppresses duplicate diagnostics. status = 1 -- 2.47.0

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[PROPOSED 1/3] Pacify gcc -Wsuggest-attribute=format sans snprintf in zdump
by Paul Eggert Dec. 1, 2024

Dec. 1, 2024

* zdump.c (my_snprintf): Now a static function defined only if !HAVE_SNPRINTF, with "#define snprintf my_sprintf" at the end. This lessens disruption to mainline code. All uses changed. Add ATTRIBUTE_FORMAT((printf, 3, 4)) to pacify gcc -Wsuggest-attribute=format. --- zdump.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) diff --git a/zdump.c b/zdump.c index c988f6b3..ea051adf 100644 --- a/zdump.c +++ b/zdump.c @@ -914,13 +914,10 @@ showextrema(timezone_t tz, char *zone, time_t lo, struct tm *lotmp, time_t hi) } } -#if HAVE_SNPRINTF -# define my_snprintf snprintf -#else +/* On pre-C99 platforms, a snprintf substitute good enough for us. */ +#if !HAVE_SNPRINTF # include <stdarg.h> - -/* A substitute for snprintf that is good enough for zdump. */ -static int +ATTRIBUTE_FORMAT((printf, 3, 4)) static int my_snprintf(char *s, size_t size, char const *format, ...) { int n; @@ -948,6 +945,7 @@ my_snprintf(char *s, size_t size, char const *format, ...) va_end(args); return n; } +# define snprintf my_snprintf #endif /* Store into BUF, of size SIZE, a formatted local time taken from *TM. @@ -962,10 +960,10 @@ format_local_time(char *buf, ptrdiff_t size, struct tm const *tm) { int ss = tm->tm_sec, mm = tm->tm_min, hh = tm->tm_hour; return (ss - ? my_snprintf(buf, size, "%02d:%02d:%02d", hh, mm, ss) + ? snprintf(buf, size, "%02d:%02d:%02d", hh, mm, ss) : mm - ? my_snprintf(buf, size, "%02d:%02d", hh, mm) - : my_snprintf(buf, size, "%02d", hh)); + ? snprintf(buf, size, "%02d:%02d", hh, mm) + : snprintf(buf, size, "%02d", hh)); } /* Store into BUF, of size SIZE, a formatted UT offset for the @@ -1000,10 +998,10 @@ format_utc_offset(char *buf, ptrdiff_t size, struct tm const *tm, time_t t) mm = off / 60 % 60; hh = off / 60 / 60; return (ss || 100 <= hh - ? my_snprintf(buf, size, "%c%02ld%02d%02d", sign, hh, mm, ss) + ? snprintf(buf, size, "%c%02ld%02d%02d", sign, hh, mm, ss) : mm - ? my_snprintf(buf, size, "%c%02ld%02d", sign, hh, mm) - : my_snprintf(buf, size, "%c%02ld", sign, hh)); + ? snprintf(buf, size, "%c%02ld%02d", sign, hh, mm) + : snprintf(buf, size, "%c%02ld", sign, hh)); } /* Store into BUF (of size SIZE) a quoted string representation of P. @@ -1106,7 +1104,7 @@ istrftime(char *buf, ptrdiff_t size, char const *time_fmt, for (abp = ab; is_alpha(*abp); abp++) continue; len = (!*abp && *ab - ? my_snprintf(b, s, "%s", ab) + ? snprintf(b, s, "%s", ab) : format_quoted_string(b, s, ab)); if (s <= len) return false; @@ -1114,7 +1112,7 @@ istrftime(char *buf, ptrdiff_t size, char const *time_fmt, } formatted_len = (tm->tm_isdst - ? my_snprintf(b, s, &"\t\t%d"[show_abbr], tm->tm_isdst) + ? snprintf(b, s, &"\t\t%d"[show_abbr], tm->tm_isdst) : 0); } break; -- 2.43.0

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