March 2024 - tz - lists.iana.org

mktime() clarification
by Dag-Erling Smørgrav March 26, 2024

March 26, 2024

Both the C standard and POSIX state that mktime() returns -1 on failure; POSIX additionally states that it sets errno. However, since -1 is also a valid result (representing 23:59:59 UTC on 1969-12-31) and POSIX never guarantees that a successful call does not modify errno, it seems to me that the only reliable way to determine whether mktime() succeeded, within the bounds of the aforementioned standards, is to set tm_wday or tm_yday to an out-of-bounds value (e.g. -1) prior to calling mktime() and check whether it has been modified on return. As far as I can tell, this has been the case ever since mktime() was introduced in POSIX.1 in 1988 and XPG3 and ANSI C in 1989. Am I wrong? Would it be a mistake to state this outright in the appropriate manual page? DES -- Dag-Erling Smørgrav - des(a)des.no

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TZ Environment Variable in Australia/Lord_Howe
by Bill Seymour March 20, 2024

March 20, 2024

I notice in Australia/Lord_Howe that the TZ environment variable in the compiled TZif file is: <+1030>-10:30<+11>-11,M10.1.0,M4.1.0 Are the signs backwards, i.e., should the signs between the angle brackets be the wrong ones and the offsets after the '>' be the right ones? The Zone record in the 2024a release is: Zone Australia/Lord_Howe 10:36:20 - LMT 1895 Feb 10:00 - AEST 1981 Mar 10:30 LH +1030/+1130 1985 Jul 10:30 LH +1030/+11 --Bill Seymour

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Ubuntu drops old-style links
by Matt Johnson-Pint March 18, 2024

March 18, 2024

I just learned that Ubuntu Noble (24.04) decided to intentionally split the tzdata package. Old-style links such as US/Eastern are no longer included by default, but are available in the tzdata-legacy package instead. Just thought I'd share. I wonder if other distributions / platforms / libraries will follow suit. What do y'all think? See: https://bugs.launchpad.net/ubuntu/+source/tzdata/+bug/2058249 https://stackoverflow.com/questions/78180695/unrecognized-time-zone -Matt

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troff(1) warning on zic(8)
by Alejandro Colomar March 17, 2024

March 17, 2024

Hi Paul, I've been looking at tz.git to fix some indentation issues, and saw this warning in one page: $ man ./zic.8 troff:<standard input>:357: warning: unbalanced 'el' request $ type man man is a function man () { if command man "$@"; then command man --warnings=w "$@" > /dev/null; fi } Have a lovely day! Alex -- <https://www.alejandro-colomar.es/>

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[PATCH] tzfile.5: Fix indentation
by Alejandro Colomar March 17, 2024

March 17, 2024

RS after IP, if the indentation amount is not specified, takes the same indentation that IP had. The values being used were wrong, and by removing them, we're fixing the indentation of the page. Cc: "G. Branden Robinson" <branden(a)debian.org> Cc: Paul Eggert <eggert(a)cs.ucla.edu> Signed-off-by: Alejandro Colomar <alx(a)kernel.org> --- tzfile.5 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tzfile.5 b/tzfile.5 index 867348d6..ef0c14e6 100644 --- a/tzfile.5 +++ b/tzfile.5 @@ -42,7 +42,7 @@ .SH DESCRIPTION Fifteen bytes containing zeros reserved for future use. .IP \(bu Six four-byte integer values, in the following order: -.RS "\w' \(bu 'u" +.RS .TP "\w' 'u" .B tzh_ttisutcnt The number of UT/local indicators stored in the file. @@ -134,7 +134,7 @@ .SH DESCRIPTION is in the range [\-89999, 93599] (i.e., more than \-25 hours and less than 26 hours); this allows easy support by implementations that already support the POSIX-required range [\-24:59:59, 25:59:59]. -.RS "\w' 'u" +.RS .IP \(bu "\w'\(bu 'u" .B tzh_charcnt bytes that represent time zone designations, -- 2.43.0

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Bug#1067022: man2html: Segmentation fault with tzfile(5)
by Alejandro Colomar March 16, 2024

March 16, 2024

Package: man2html Version: 1.6g-16 Severity: normal Tags: upstream X-Debbugs-Cc: Alejandro Colomar <alx(a)kernel.org>, Paul Eggert <eggert(a)cs.ucla.edu>, "G. Branden Robinson" <branden(a)debian.org>, linux-man(a)vger.kernel.org, groff(a)gnu.org, tz(a)iana.org Dear Maintainer, The page tzfile(5) from tzdb-2024a manages to consistently produce a Segmentation fault with man2html(1). Below is a reproducer: alx@debian:~/tmp$ wget https://data.iana.org/time-zones/releases/tzdb-2024a.tar.lz 2>/dev/null alx@debian:~/tmp$ tar xf tzdb-2024a.tar.lz alx@debian:~/tmp$ man2html tzdb-2024a/tzfile.5 Content-type: text/html; charset=UTF-8 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <HTML><HEAD><TITLE>Man page of tzfile</TITLE> </HEAD><BODY> <H1>tzfile</H1> Section: File Formats (5)<BR>Updated: <BR><A HREF="#index">Index</A> <A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR> <A NAME="lbAB"> </A> <H2>NAME</H2> tzfile - timezone information <A NAME="lbAC"> </A> <H2>DESCRIPTION</H2> The timezone information files used by <B><A HREF="/cgi-bin/man/man2html?3+tzset">tzset</A></B>(3) are typically found under a directory with a name like <I>/usr/share/zoneinfo</I>. These files use the format described in Internet RFC 8536. Each file is a sequence of 8-bit bytes. In a file, a binary integer is represented by a sequence of one or more bytes in network order (bigendian, or high-order byte first), with all bits significant, a signed binary integer is represented using two's complement, and a boolean is represented by a one-byte binary integer that is either 0 (false) or 1 (true). The format begins with a 44-byte header containing the following fields: Segmentation fault alx@debian:~/tmp$ dpkg -l | grep man2html ii man2html 1.6g-16 amd64 browse man pages in your web browser ii man2html-base 1.6g-16 amd64 convert man pages into HTML format I've refreshed this page today, and the previous version I used didn't have this crash. Below is the part of the diff that I think is responsible for the crash: diff --git a/man5/tzfile.5 b/man5/tzfile.5 index 45afecc10..867348d67 100644 --- a/man5/tzfile.5 +++ b/man5/tzfile.5 @@ -26,23 +26,24 @@ .SH DESCRIPTION and a boolean is represented by a one-byte binary integer that is either 0 (false) or 1 (true). The format begins with a 44-byte header containing the following fields: -.IP * 2 +.RS "\w' 'u" +.IP \(bu "\w'\(bu 'u" The magic four-byte ASCII sequence .q "TZif" identifies the file as a timezone information file. BTW, I noticed that the upstream homepage is dead: <http://users.actrix.gen.nz/michael/vhman2html.html>. Is this project defunct? Have a lovely day! Alex -- System Information: Debian Release: trixie/sid APT prefers unstable APT policy: (500, 'unstable'), (1, 'experimental') Architecture: amd64 (x86_64) Kernel: Linux 6.8.0-rc7-alx-dirty (SMP w/24 CPU threads; PREEMPT) Locale: LANG=C.utf8, LC_CTYPE=C.utf8 (charmap=UTF-8), LANGUAGE not set Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages man2html depends on: ii debconf [debconf-2.0] 1.5.86 ii gawk 1:5.2.1-2 ii libc6 2.37-15.1 ii lynx 2.9.0rel.0-2+b1 ii man-db 2.12.0-3 ii man2html-base 1.6g-16 ii sensible-utils 0.0.22 man2html recommends no packages. Versions of packages man2html suggests: ii firefox-esr [www-browser] 115.8.0esr-1+b1 ii lynx [www-browser] 2.9.0rel.0-2+b1 pn swish++ <none> ii w3m [www-browser] 0.5.3+git20230121-2+b3 -- debconf information: man2html/index_manpages: true

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People Hate Daylight Saving. Science Tells Us Why.
by Brian Inglis March 14, 2024

March 14, 2024

A summary of various studies and opinions: https://undark.org/2024/03/11/time-zones-daylight-saving/ -- Take care. Thanks, Brian Inglis Calgary, Alberta, Canada La perfection est atteinte Perfection is achieved non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut -- Antoine de Saint-Exupéry

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Asia/Shanghai error?
by Komka Péter March 13, 2024

March 13, 2024

Hi, tzdata2024a contains (erroneously?): # Zone NAME STDOFF RULES FORMAT [UNTIL] # Beijing time, used throughout China; represented by Shanghai. #STDOFF 8:05:43.2 Zone Asia/Shanghai 8:05:43 - LMT 1901 8:00 Shang C%sT 1949 May 28 8:00 PRC C%sT <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< # Xinjiang time, used by many in western China; represented by Ürümqi / Ürümchi # / Wulumuqi. (Please use Asia/Shanghai if you prefer Beijing time.) Zone Asia/Urumqi 5:50:20 - LMT 1928 6:00 - +06 Shanghai refers to the rule "PRC". # Rule NAME FROM TO - IN ON AT SAVE LETTER/S Rule PRC 1986 only - May 4 2:00 1:00 D Rule PRC 1986 1991 - Sep Sun>=11 2:00 0 S Rule PRC 1987 1991 - Apr Sun>=11 2:00 1:00 D Rule PRC was only in use until 1991. Currently, in 2024, there is no rule "PRC" in use. The local time Asia/Shanghai refers to a non-existing rule. Possibly: Asia/Shanghai time currently (2024) has NO DST-rule. Similarly to Asia/Urumqi. https://en.wikipedia.org/wiki/China says: "Time zone UTC+8 (CST) / DST is not observed." https://www.timeanddate.com/worldclock/china shows: there is [officially] only one time in China, "CST", "UTC +8". Even is Ürümqi. https://www.timeanddate.com/time/change/china (a sub-link from the previos link) "Daylight Saving Time (DST) Not Observed in Year 2024" "The previous DST change in China was on 15 September 1991." -- Komka Peter (please do not spam)

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Re: [tz] Some issues regarding the tz database
by Paul Eggert March 11, 2024

March 11, 2024

On 2024-03-10 21:07, xzx_work_2020 wrote: > 1) About echo" IST-2IDT, M3.44/26, M10.5.0 ">/tmp/TZ": > I don't know why there is an extra space in the mail, but I actually use is no space. Oh, one other thing, it should be "M3.4.4" not "M3.44".

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Re: [tz] Some issues regarding the tz database
by Paul Eggert March 10, 2024

March 10, 2024

On 2024-03-10 01:42, xzx_work_2020 wrote: > I used 'cat Asia/Jerusalem' and the result was "IST-2IDT, M3.44/26, M10.5.0". > However, when I used "echo" IST-2IDT, M3.44/26, M10.5.0 ">/tmp/TZ", this did not work. I would omit the extra spaces after the ","s. Also, don't you need to put it into /etc/TZ? That is, the command should be something like this: echo "IST-2IDT,M3.4.4/26,M10.5.0" >/etc/TZ if you're using OpenWRT with musl. > Question 1: Is it necessary to handle items that exceed 24 hours during use in this way? POSIX.1-2017 does not require support for the "/26". However, it is a common extension (it's in glibc for example), and the next POSIX release is planned to require support for times from -167:59:50 through +167:59:59. As I understand it, older versions of musl did not support "/26", but newer versions do. (I don't know when this feature was added to musl.) Perhaps all you need to do is upgrade musl versions. > Question 2: I saw from online sources that Asia/Jerusalem entered daylight saving time at 2:00 pm on Friday, March 29, 2024. However, the data in the database seems to be calculated to be 2:00 pm on Friday, the fourth week of March, which is also 2:00 pm on Friday, March 22, 2024. Did I misunderstand this? Or is there an error in the data in the database? I think you misunderstood it. The relevant line in the "asia" file is: Rule Zion 2013 max - Mar Fri>=23 2:00 1:00 D which says the transition is the first Friday on or after March 23, at 02:00. This matches current Israeli law, which says the transition occurs at 2 am on the Friday before March's last Sunday. This rule cannot be encoded in a POSIX.1-2017 TZ setting, which is partly why the next POSIX release will allow the "/26".

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