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Chilean time change
by Glenn Eychaner Feb. 23, 2015

Feb. 23, 2015

I have been following Diario Official for the past couple of weeks (http://www.diariooficial.interior.gob.cl) and have yet to see an official announcement regarding the change of time zone rules. In addition, SHOA has yet to update their web site (http://www.horaoficial.cl/cambio_hora.html) -G. -- Glenn Eychaner (geychaner(a)lco.cl) Telescope Systems Programmer, Las Campanas Observatory

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An outline of a possible solution for sensible leap-second support.
by random832＠fastmail.us Feb. 16, 2015

Feb. 16, 2015

Right now, very few people use the leap second support in tzcode. This may represent a lack of demand, or it may be due to the fact that you cannot have both leap second support and POSIX compliance at the same time. Even when people do use it, it's often done in an incomplete and incorrect way (e.g. by specifying the "right" folder directly in the TZ variable). If the tz project intends to provide leap second support, I would argue that it should be in a form that people can actually use. Also, general question: is there any standard on how leap seconds are to be handled in timezones that have an offset that is not a multiple of one whole minute? What does tzcode do now? ---- Abandon entirely the time2posix/posix2time functions, the "right" directory, and the notion of a time_t representation where e.g. 2000-01-01T00:00:00Z is represented by a value of 946684822 rather than 946684800. Very few people use them, and many of those who do use them do so incorrectly even disregarding the issue of programs they may run that do not call the conversion functions when they should. Remove support for generating tzdata files with leap second data, and report an error if one is loaded. Create a non-ambiguous representation for leap-aware timestamps. My suggestion is a pair of {time_t time; int leap;}, with time being (for leap seconds) the POSIX timestamp for the preceding normal second, and leap=1 for s=60, leap=2 for s=61, etc. Define a function interface which leap-aware systems may use to return the correct time, with leap seconds and without any skew to attempt to compensate for them. Tzcode to contain a dummy version that returns {time, 0}. The value of the existing time() function around leap seconds (e.g. whether it reports 23:59:59 twice, 00:00:00 twice, or implements some form of skew over the course of the minute/hour/day) is implementation-defined. (Arguably this new interface should also return the best known correct time immediately rather than implementing skew in the case of NTP adjustments as well, since unlike time() it is not expected to be used by legacy programs as a pseudo-monotonic counter) Define a file format and location (e.g. zoneinfo/leapdb) to store a single copy of leap second information for use by the following functions. Define leap-aware interval-measurement (difftime) and interval-addition (+ and - operator) functions. For example, since there was a leap second in June 2012, difftime_l({1341100802, 0}, {1341100798, 0}) [2012-07-01T00:00:02Z minus 2012-06-30T23:59:58Z] is 5 rather than the conventional 4. This is in contrast to the current implementation which represents these times with different values that differ by 5, and implements difftime by simple subtraction. Define leap-aware versions of mktime_r, localtime_r, mktime_rz, localtime_rz, gmtime_r, timegm_r, which use the new representation where the normal ones use time_t. Expanded scope (not part of tzcode/tzdata itself) - provide recommendations of how to represent leap second times in filesystem structures, archive structures, struct stat, struct timespec, and to maintain backwards compatibility with existing ABIs which do not provide this information (extending the range of an existing sub-second field is worth considering in some cases, though 32-bit signed nanoseconds only have room for one additional second in this way.)

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leap second insertions
by Nathan Justus Feb. 16, 2015

Feb. 16, 2015

>One additional second is all one needs, no? Two leap seconds are never inserted adjacent to each other. So POSIX's 'struct timespec' suffices to >represent leap seconds, and there's no need for a new data type here, just new operations on the type. You could start by adding a new clock to >clock_gettime, a clock that respects leap seconds. There has never been more than one leap second added in any one instance, but as far as I know, nothing precludes adding more than one at any one time. But, I daresay there would be a really significant event that would cause it, such as an asteroid strike that affect the day :) Nathan

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The zoneinfo file system tree structure ?
by J William Piggott Feb. 13, 2015

Feb. 13, 2015

[please cc me, I am not subscribed] Hello, I have been working on Util-linux' hwclock and other GNU/Linux date-time issues. I have a couple of questions that I hope someone here can answer. The tz database file system tree was changed on May 25 1998, moving 'right' and 'posix' from subdirectories of zoneinfo to sibling directories. However GNU libc continued to use the old structure until it stopped including the data files on Mar 7 2012. Now some Linux distributions are still using the old subdirectory tree structure. Is there a reason that the old tree structure is still being used? Does it break something to have 'right' and 'posix' as sibling directories? I ask because the problems that were the catalyst for the change in 1998 are still happening. It seems to me like it was a good solution, but nobody used it. If I may ask one more favor, could you please review the information below which I have added to the hwclock man-page? I still need to include information about using TZDIR. Thank you very much, William POSIX vs 'RIGHT' A discussion on date-time configuration would be incomplete without addressing timezones, this is mostly well covered by tzset(3). One area that seems to have no documentation is the 'right' directory of the IANA Time Zone Database, aka tz, aka zoneinfo. There are two separate databases in the zoneinfo system, posix and 'right'. 'Right' (now named leaps) includes leap seconds and posix does not. To use the 'right' database the System Clock must be kept in UTC + leap_seconds, i.e., TAI - 10. This allows calculating the exact number of seconds between two dates that cross a leap second epoch. The System Clock is then converted to the correct civil time, including UTC, by using the 'right' timezone files which subtract the leap sec- onds. Note: this configuration is considered experimental and is known to have issues. To configure a system to use a particular database all of the files located in its directory must be copied to the root of /usr/share/zoneinfo. Files are never used directly from the posix or 'right' subdirectories, e.g., TZ='right/Europe/Dublin'. This habit was becoming so common that the upstream zoneinfo project restructured the system's file tree by moving the posix and 'right' subdirectories out of the zoneinfo directory and into sibling directories: /usr/share/zoneinfo /usr/share/posix /usr/share/leaps Unfortunately, some Linux distributions are changing it back to the old tree structure in their packages. So the problem of system administra- tors reaching into the 'right' subdirectory persists. This causes the system timezone to be configured to include leap seconds while the zoneinfo database is still configured to exclude them. Then when an application such as a World Clock needs the South_Pole timezone file; or an email MTA, or hwclock needs the UTC timezone file; they fetch it from the root of /usr/share/zoneinfo , because that is what they are supposed to do. Those files exclude leap seconds, but the System Clock now includes them, causing an incorrect time conversion. Attempting to mix and match files from these separate databases will not work, because they each require the System Clock to use a different timescale. The zoneinfo database must be configured to use either posix or 'right', as described above.

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[PROPOSED PATCH] * northamerica (America/Cayman): Put Link after Zone.
by Paul Eggert Feb. 12, 2015

Feb. 12, 2015

--- northamerica | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/northamerica b/northamerica index cb27bd5..77463da 100644 --- a/northamerica +++ b/northamerica @@ -2592,7 +2592,7 @@ Zone Atlantic/Bermuda -4:19:18 - LMT 1930 Jan 1 2:00 # Hamilton -4:00 US A%sT # Cayman Is -Link America/Panama America/Cayman +# See America/Panama. # Costa Rica @@ -3115,6 +3115,7 @@ Zone America/Managua -5:45:08 - LMT 1890 Zone America/Panama -5:18:08 - LMT 1890 -5:19:36 - CMT 1908 Apr 22 # Colón Mean Time -5:00 - EST +Link America/Panama America/Cayman # Puerto Rico # There are too many San Juans elsewhere, so we'll use 'Puerto_Rico'. -- 2.1.0

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[PROPOSED PATCH] Move four out-of-scope zones to 'backzone'
by Paul Eggert Feb. 12, 2015

Feb. 12, 2015

* NEWS: Document this. * australasia (Pacific/Guam): Now a link to Pacific/Guam. (Pacific/Midway): Now a link to Pacific/Pago_Pago. * backzone (America/Antigua, America/Cayman, Pacific/Miday) (Pacific/Saipan): Move these four entries here from the other files. * checktab.awk: Remove special cases for the four zones. * northamerica (America/Cayman): Now a link to America/Panama. (America/Antigua): Move to ... * southamerica (America/Antigua): ... here, and make it a link to America/Port_of_Spain. --- NEWS | 9 +++++++++ australasia | 27 ++++----------------------- backzone | 36 ++++++++++++++++++++++++++++++++++++ checktab.awk | 9 --------- northamerica | 12 ++---------- southamerica | 1 + 6 files changed, 52 insertions(+), 42 deletions(-) diff --git a/NEWS b/NEWS index b70ce73..33e983f 100644 --- a/NEWS +++ b/NEWS @@ -2,6 +2,15 @@ News for the tz database Unreleased, experimental changes + Changes affecting past time stamps + + Some more zones have been turned into links, when they differed + from existing zones only for older time stamps. As usual, + these changes affect UTC offsets in pre-1970 time stamps only. + Their old contents have been moved to the 'backzone' file. + The affected zones are: America/Antigua, America/Cayman, + Pacific/Midway, and Pacific/Saipan. + Changes affecting commentary Cite the recent Mexican decree changing Quintana Roo's time zone. diff --git a/australasia b/australasia index 911e681..3e2c0b3 100644 --- a/australasia +++ b/australasia @@ -373,6 +373,7 @@ Zone Pacific/Guam -14:21:00 - LMT 1844 Dec 31 9:39:00 - LMT 1901 # Agana 10:00 - GST 2000 Dec 23 # Guam 10:00 - ChST # Chamorro Standard Time +Link Pacific/Guam Pacific/Saipan # N Mariana Is # Kiribati # Zone NAME GMTOFF RULES FORMAT [UNTIL] @@ -388,12 +389,7 @@ Zone Pacific/Kiritimati -10:29:20 - LMT 1901 14:00 - LINT # N Mariana Is -# Zone NAME GMTOFF RULES FORMAT [UNTIL] -Zone Pacific/Saipan -14:17:00 - LMT 1844 Dec 31 - 9:43:00 - LMT 1901 - 9:00 - MPT 1969 Oct # N Mariana Is Time - 10:00 - MPT 2000 Dec 23 - 10:00 - ChST # Chamorro Standard Time +# See Pacific/Guam. # Marshall Is # Zone NAME GMTOFF RULES FORMAT [UNTIL] @@ -563,6 +559,7 @@ Zone Pacific/Pago_Pago 12:37:12 - LMT 1879 Jul 5 -11:00 - NST 1967 Apr # N=Nome -11:00 - BST 1983 Nov 30 # B=Bering -11:00 - SST # S=Samoa +Link Pacific/Pago_Pago Pacific/Midway # in US minor outlying islands # Samoa (formerly and also known as Western Samoa) @@ -744,23 +741,7 @@ Zone Pacific/Funafuti 11:56:52 - LMT 1901 # uninhabited # Midway -# -# From Mark Brader (2005-01-23): -# [Fallacies and Fantasies of Air Transport History, by R.E.G. Davies, -# published 1994 by Paladwr Press, McLean, VA, USA; ISBN 0-9626483-5-3] -# reproduced a Pan American Airways timetable from 1936, for their weekly -# "Orient Express" flights between San Francisco and Manila, and connecting -# flights to Chicago and the US East Coast. As it uses some time zone -# designations that I've never seen before:.... -# Fri. 6:30A Lv. HONOLOLU (Pearl Harbor), H.I. H.L.T. Ar. 5:30P Sun. -# " 3:00P Ar. MIDWAY ISLAND . . . . . . . . . M.L.T. Lv. 6:00A " -# -Zone Pacific/Midway -11:49:28 - LMT 1901 - -11:00 - NST 1956 Jun 3 - -11:00 1:00 NDT 1956 Sep 2 - -11:00 - NST 1967 Apr # N=Nome - -11:00 - BST 1983 Nov 30 # B=Bering - -11:00 - SST # S=Samoa +# See Pacific/Pago_Pago. # Palmyra # uninhabited since World War II; was probably like Pacific/Kiritimati diff --git a/backzone b/backzone index fc20ea5..31a3f5a 100644 --- a/backzone +++ b/backzone @@ -255,6 +255,11 @@ Zone Africa/Timbuktu -0:12:04 - LMT 1912 Zone America/Anguilla -4:12:16 - LMT 1912 Mar 2 -4:00 - AST +# Antigua and Barbuda +Zone America/Antigua -4:07:12 - LMT 1912 Mar 2 + -5:00 - EST 1951 + -4:00 - AST + # Chubut, Argentina # The name "Comodoro Rivadavia" exceeds the 14-byte POSIX limit. Zone America/Argentina/ComodRivadavia -4:30:00 - LMT 1894 Oct 31 @@ -274,6 +279,11 @@ Zone America/Aruba -4:40:24 - LMT 1912 Feb 12 # Oranjestad -4:30 - ANT 1965 # Netherlands Antilles Time -4:00 - AST +# Cayman Is +Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown + -5:07:11 - KMT 1912 Feb # Kingston Mean Time + -5:00 - EST + # Canada Zone America/Coral_Harbour -5:32:40 - LMT 1884 -5:00 NT_YK E%sT 1946 @@ -599,3 +609,29 @@ Zone Indian/Mayotte 3:00:56 - LMT 1911 Jul # Mamoutzou # US minor outlying islands Zone Pacific/Johnston -10:00 - HST + +# US minor outlying islands +# +# From Mark Brader (2005-01-23): +# [Fallacies and Fantasies of Air Transport History, by R.E.G. Davies, +# published 1994 by Paladwr Press, McLean, VA, USA; ISBN 0-9626483-5-3] +# reproduced a Pan American Airways timetable from 1936, for their weekly +# "Orient Express" flights between San Francisco and Manila, and connecting +# flights to Chicago and the US East Coast. As it uses some time zone +# designations that I've never seen before:.... +# Fri. 6:30A Lv. HONOLOLU (Pearl Harbor), H.I. H.L.T. Ar. 5:30P Sun. +# " 3:00P Ar. MIDWAY ISLAND . . . . . . . . . M.L.T. Lv. 6:00A " +# +Zone Pacific/Midway -11:49:28 - LMT 1901 + -11:00 - NST 1956 Jun 3 + -11:00 1:00 NDT 1956 Sep 2 + -11:00 - NST 1967 Apr # N=Nome + -11:00 - BST 1983 Nov 30 # B=Bering + -11:00 - SST # S=Samoa + +# N Mariana Is +Zone Pacific/Saipan -14:17:00 - LMT 1844 Dec 31 + 9:43:00 - LMT 1901 + 9:00 - MPT 1969 Oct # N Mariana Is Time + 10:00 - MPT 2000 Dec 23 + 10:00 - ChST # Chamorro Standard Time diff --git a/checktab.awk b/checktab.awk index 9a452b6..cf2c726 100644 --- a/checktab.awk +++ b/checktab.awk @@ -12,15 +12,6 @@ BEGIN { # A special (and we hope temporary) case. tztab["America/Montreal"] = 1 - # Some more special cases; these are zones that should probably - # be turned into links. - if (zone_table == "zone1970.tab") { - tztab["America/Antigua"] = 1 - tztab["America/Cayman"] = 1 - tztab["Pacific/Midway"] = 1 - tztab["Pacific/Saipan"] = 1 - } - while (getline <iso_table) { iso_NR++ if ($0 ~ /^#/) continue diff --git a/northamerica b/northamerica index ad7e106..cb27bd5 100644 --- a/northamerica +++ b/northamerica @@ -2524,13 +2524,8 @@ Zone America/Santa_Isabel -7:39:28 - LMT 1922 Jan 1 0:20:32 ############################################################################### # Anguilla -# See America/Port_of_Spain. - # Antigua and Barbuda -# Zone NAME GMTOFF RULES FORMAT [UNTIL] -Zone America/Antigua -4:07:12 - LMT 1912 Mar 2 - -5:00 - EST 1951 - -4:00 - AST +# See America/Port_of_Spain. # Bahamas # @@ -2597,10 +2592,7 @@ Zone Atlantic/Bermuda -4:19:18 - LMT 1930 Jan 1 2:00 # Hamilton -4:00 US A%sT # Cayman Is -# Zone NAME GMTOFF RULES FORMAT [UNTIL] -Zone America/Cayman -5:25:32 - LMT 1890 # Georgetown - -5:07:11 - KMT 1912 Feb # Kingston Mean Time - -5:00 - EST +Link America/Panama America/Cayman # Costa Rica diff --git a/southamerica b/southamerica index a64a438..fc0cc54 100644 --- a/southamerica +++ b/southamerica @@ -1604,6 +1604,7 @@ Zone America/Port_of_Spain -4:06:04 - LMT 1912 Mar 2 # These all agree with Trinidad and Tobago since 1970. Link America/Port_of_Spain America/Anguilla +Link America/Port_of_Spain America/Antigua Link America/Port_of_Spain America/Dominica Link America/Port_of_Spain America/Grenada Link America/Port_of_Spain America/Guadeloupe -- 2.1.0

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Brazil considering delay to end of DST
by Paul Eggert Feb. 12, 2015

Feb. 12, 2015

The government of Brazil is considering ending daylight saving time later than planned. Currently DST is scheduled to end February 22 at 00:00 local time. This may be delayed by a month. A decision is planned by February 12. Brazil is getting less rain than expected -- their January was the driest in 85 years -- and hydroelectric plants produce most of Brazil's electricity. The hope is that daylight saving time will lower power consumption peaks, making power blackouts less likely. Sources: Jelmayer R. Brazil evaluates extending daylight saving time. Dow Jones Business News 2015-02-06. http://www.nasdaq.com/article/brazil-evaluates-extending-daylight-saving-ti… Governo estuda estender o horário de verão para economizar energia. Jornal Nacional 2015-02-05. http://g1.globo.com/economia/noticia/2015/02/governo-estuda-estender-o-hora… Watts J. Brazil’s worst drought in history prompts protests and blackouts. The Guardian 2015-01-23. http://www.theguardian.com/world/2015/jan/23/brazil-worst-drought-history

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tz-latest checksum
by Paul G Feb. 7, 2015

Feb. 7, 2015

I'm looking into writing a python script which retrieves the latest timezone database from the FTP server, but I'm wondering if there's anywhere that a checksum of the tz-latest files can be found anywhere. At the moment, we manually specify the latest version of the database, and calculate the sha512 checksum whenever it is updated. I see that the GPG signature is available, but I would very much like to avoid adding any dependencies to the library. Is there anywhere that I retrieve the checksum for the latest tzdata file using one of the hashes supported by hashlib? (SHA1, SHA256, SHA384, SHA512 or MD5) Of course this defeats the implied MITM protection that retrieving a "known good" or signed checksum provides, but it at least retains the checksum / corrupted file protection. Thanks!

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Re: [tz] Positive leap second on 2015-06-30.
by Denis Excoffier Feb. 7, 2015

Feb. 7, 2015

On 2015-01-06 21:22, Tim Parenti wrote: > +# Some systems implement leap seconds by amortizing the leap second > +# over the last few minutes of the day. The frequency of the local > +# clock is decreased (or increased) to realize the positive (or > +# negative) leap second. This method removes the time step described > +# above. Although the long-term behavior of the time scale is correct > +# in this case, this method introduces an error during the adjustment > +# period both in time and in frequency with respect to the official > +# defintion of UTC. s/defintion/definition/ Regards, Denis Excoffier.

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Chilean time change
by Glenn Eychaner Feb. 7, 2015

Feb. 7, 2015

I have been following Diario Official for the past couple of weeks (http://www.diariooficial.interior.gob.cl) and have yet to see an official announcement regarding the change of time zone rules. In addition, SHOA has yet to update their web site (http://www.horaoficial.cl/cambio_hora.html) -G. -- Glenn Eychaner (geychaner(a)lco.cl) Telescope Systems Programmer, Las Campanas Observatory

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