- tz - lists.iana.org

RE: glibc, Linux: about the time zone transition values in the lo calt ime file
by Olson, Arthur David (NIH/NCI) Feb. 3, 2005

Feb. 3, 2005

Here at elsie the Central time zone seems okay; witness this excerpt from the output of "zdump -v US/Central": ... US/Central Sun Apr 4 07:59:59 2004 UTC = Sun Apr 4 01:59:59 2004 CST isdst=0 US/Central Sun Apr 4 08:00:00 2004 UTC = Sun Apr 4 03:00:00 2004 CDT isdst=1 US/Central Sun Oct 31 06:59:59 2004 UTC = Sun Oct 31 01:59:59 2004 CDT isdst=1 US/Central Sun Oct 31 07:00:00 2004 UTC = Sun Oct 31 01:00:00 2004 CST isdst=0 US/Central Sun Apr 3 07:59:59 2005 UTC = Sun Apr 3 01:59:59 2005 CST isdst=0 US/Central Sun Apr 3 08:00:00 2005 UTC = Sun Apr 3 03:00:00 2005 CDT isdst=1 US/Central Sun Oct 30 06:59:59 2005 UTC = Sun Oct 30 01:59:59 2005 CDT isdst=1 US/Central Sun Oct 30 07:00:00 2005 UTC = Sun Oct 30 01:00:00 2005 CST isdst=0 US/Central Sun Apr 2 07:59:59 2006 UTC = Sun Apr 2 01:59:59 2006 CST isdst=0 US/Central Sun Apr 2 08:00:00 2006 UTC = Sun Apr 2 03:00:00 2006 CDT isdst=1 US/Central Sun Oct 29 06:59:59 2006 UTC = Sun Oct 29 01:59:59 2006 CDT isdst=1 US/Central Sun Oct 29 07:00:00 2006 UTC = Sun Oct 29 01:00:00 2006 CST isdst=0 ... --ado

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Re: Tzcode2004d.tar.gz
by Olson, Arthur David (NIH/NCI) Feb. 3, 2005

Feb. 3, 2005

The elsie copy has now been given the correct (2005) name. --ado

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Tzcode2004d.tar.gz
by Olson, Arthur David (NIH/NCI) Feb. 2, 2005

Feb. 2, 2005

The file... ftp://elsie.nci.nih.gov/pub/tzcode2004d.tar.gz ...is now available. This incorporates the (now slightly modified) changes circulated last week on the time zone mailing list to: make zic complain about links to links if the -v flag is used; have "make public" do more code checking; and add an include to "localtime.c" for the benefit of gcc systems. Note that there are no data changes. Expect one more batch of delinting changes for the code. --ado

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glibc, Linux: about the time zone transition values in the localt ime file
by Fei Yuming-CYF001 Feb. 1, 2005

Feb. 1, 2005

Dear Sir: On Linux systems, it seems that the transitions stored in the localtime file are not the current time to start the transition, but the new local current time right after the transition. For example, I have the glibc-2.2.5 library on my Linux 2.4.20 system, my timezone is set to US/Central and my current time is in CST. The /etc/localtime (or /usr/share/zoneinfo/US/Central) shows that in 2005, the time to transfer into DST is 1112515200 seconds, i.e. Sun Apr 3 03:00:00 2005. (This can be got, e.g., by breaking into the glibc-2.2.5/time/tzfile.c's __tzfile_read() function, and printing out the transitions values, i.e. transitions[169] == 1112515200). However, as we know, the transition to DST is Apr 3 02:00:00 --> Apr 3 03:00:00. The time after the transition (i.e. 03:00:00) instead of the current time to start the transition (ie.. 02:00:00) has been stored in the localtime file. Could you please let me know what the reason it is to do so (i.e. why not storing 02:00:00)? I will highly appreciate your help! Yuming

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Time Zones 1914
by Hall, Jr., Owen Jan. 29, 2005

Jan. 29, 2005

Hi, I am doing some research on the Goeben during August 4 - 8, 1914. Do you know the time zone for Rome and Messina during this period? Today they are GMT +1. Thanks in advance. Professor Hall

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Time in Ireland
by Joseph S. Myers Jan. 26, 2005

Jan. 26, 2005

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Proposed changes to localtime.c, zic.c, and Makefile
by Olson, Arthur David (NIH/NCI) Jan. 24, 2005

Jan. 24, 2005

Here are proposed changes to: 1. localtime.c, to include "float.h" for the benefit of some gcc systems (thanks to Bradley White for finding the problem). 2. zic.c, to complain about links to links if the "-v" flag is used. 3. Makefile, to ensure that a "make public" is done with the benefit of gcc diagnostics. --ado ------- localtime.c ------- *** /tmp/geta15164 Mon Jan 24 12:20:36 2005 --- /tmp/getb15164 Mon Jan 24 12:20:36 2005 *************** *** 5,11 **** #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)localtime.c 7.89"; #endif /* !defined NOID */ #endif /* !defined lint */ --- 5,11 ---- #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)localtime.c 7.90"; #endif /* !defined NOID */ #endif /* !defined lint */ *************** *** 20,25 **** --- 20,26 ---- #include "private.h" #include "tzfile.h" #include "fcntl.h" + #include "float.h" /* for FLT_MAX and DBL_MAX */ /* ** SunOS 4.1.1 headers lack O_BINARY. ------- zic.c ------- *** /tmp/geta15183 Mon Jan 24 12:20:47 2005 --- /tmp/getb15183 Mon Jan 24 12:20:47 2005 *************** *** 1,4 **** ! static char elsieid[] = "@(#)zic.c 7.118"; /* ** Regardless of the type of time_t, we do our work using this type. --- 1,4 ---- ! static char elsieid[] = "@(#)zic.c 7.119"; /* ** Regardless of the type of time_t, we do our work using this type. *************** *** 579,584 **** --- 579,589 ---- for (i = 0; i < nlinks; ++i) { eat(links[i].l_filename, links[i].l_linenum); dolink(links[i].l_from, links[i].l_to); + if (noise) + for (j = 0; j < nlinks; ++j) + if (strcmp(links[i].l_to, + links[j].l_from) == 0) + warning("link to link"); } if (lcltime != NULL) { eat("command line", 1); ------- Makefile ------- *** /tmp/geta15240 Mon Jan 24 12:21:57 2005 --- /tmp/getb15240 Mon Jan 24 12:21:57 2005 *************** *** 1,4 **** ! # @(#)Makefile 7.103 # 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). --- 1,4 ---- ! # @(#)Makefile 7.104 # 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). *************** *** 384,390 **** # The zics below ensure that each data file can stand on its own. ! public: $(ENCHILADA) zic -mkdir /tmp/,tzpublic -for i in $(TDATA) ; do zic -v -d /tmp/,tzpublic $$i 2>&1 | grep -v "starting year" ; done for i in $(TDATA) ; do zic -d /tmp/,tzpublic $$i || exit; done --- 384,392 ---- # The zics below ensure that each data file can stand on its own. ! public: ! make maintainer-clean ! make "CFLAGS=$(GCC_DEBUG_FLAGS)" -mkdir /tmp/,tzpublic -for i in $(TDATA) ; do zic -v -d /tmp/,tzpublic $$i 2>&1 | grep -v "starting year" ; done for i in $(TDATA) ; do zic -d /tmp/,tzpublic $$i || exit; done

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FW: For TZ list
by Olson, Arthur David (NIH/NCI) Jan. 23, 2005

Jan. 23, 2005

Mark Brader is not on the time zone mailing list; direct replies appropriately. --ado In a book that I'm currently reading¹, there is reproduced a Pan American Airways timeables 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, I thought the readers of the tz list might be interested. It's only a few lines, so I'll type in the entire timetable (omitting the connecting flights) for those of you might be interested. In the original, AM and PM are shown as light and bold type, and noon is N; I'll use A, P, and N respectively here. As with many railway timetables, the right-hand side reads upward. --------------------------------------------------------------------- Wed. 3:00P Lv. SAN FRANCISCO (Alameda), U.S.A. P.S.T. Ar.10:30A Tues. Thur.8:30A Ar. HONOLOLU (Pearl Harbor), H.I. H.L.T. Lv.12:00N Mon. 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 " Sat. 6:00A Lv. MIDWAY ISLAND . . . . . . . . . M.L.T. Ar. 5:00P Sat. (International Date Line) Sun. 3:00P Ar. WAKE ISLANDS . . . . . . . . . . 165° Lv. 6:00A Sun. Mon. 6:00A Lv. WAKE ISLANDS . . . . . . . . . . " Ar. 7:00P Sat. " 5:00P Ar. GUAM ISLAND . . . . . . . . . . 150° Lv. 6:00A " Tue. 6:00A Lv. GUAM ISLAND . . . . . . . . . . " Ar. 6:30P Fri. " 5:00P Ar. MANILA (Cavite), P.I. . . . . . 120° Lv. 4:00A* " ---------------------------------------------------------------------- *Departures from Manila subject to advancement to previous afternoon as occasion demands. All times are approximate other than at San Francisco Westbound and at Honolulu Eastbound. ---------------------------------------------------------------------- Clearly 120°, 150°, and 165° indicate time zones -8, -10, and -11; I guess H.L.T. and M.L.T. refer to Hawaii and Midway "Local Time". ¹Fallacies and Fantasies of Air Transport History, by R.E.G. Davies, published 1994 by Paladwr Press, McLean, VA, USA; ISBN 0-9626483-5-3. -- Mark Brader "I like to think of [this] as self-explanatory." Toronto "I hope *I* think of [it] that way." msb(a)vex.net -- Donald Westlake: "Trust Me On This" --E3771ED93.1106330125/shell.vex.net--

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Re: Defect in XSH strftime
by Paul Eggert Jan. 21, 2005

Jan. 21, 2005

In <https://www.opengroup.org/sophocles/show_mail.tpl?source=L&listname=austin-…>, Eric Blake <ebb9(a)byu.net> writes: > this means that %Y is not equivalent to %C%y, since %C is documented > to be exactly two digits This topic came up around 2004-08-20 in the tz mailing list. (Please see <http://www.twinsun.com/tz/tz-link.htm> for info about the list; it is archived in <ftp://elsie.nci.nih.gov/pub/tzarchive.gz>.) The consensus was as follows (presumably a defect report could also be submitted to POSIX, as POSIX can place requirements on strftime that are over and above what ISO C requires): * The ISO C standard is broken in this area; the standardizers did not think about the problem. (One of those involved in the tz discussion was also involved with the ISO C effort.) * A Defect Report should be submitted. (Nobody has yet done so, to my knowledge.) * Best practice (which is not currently required by any standard) is to have the following behavior, originally suggested by Arthur David Olson: - %Y always generates the mathematically-correct result, even if the expression "tm.tm_year + 1900" would overflow. - %Y is always equivalent to %C%y. - %y is always in the range [00,99]. - %C is in the range [00,99] when possible. - %C is two characters long when possible. Here are some examples: %Y %C %y 10000 100 00 9999 99 99 0999 09 99 0099 00 99 0001 00 01 0000 00 00 -001 -0 01 -099 -0 99 -999 -9 99 -1000 -10 00 -10000 -100 00 %Y %C %y -2147481749 -21474817 49 2147485547 21474855 47 Note that the last example overflows 32-bit 'int', but it is the best-practice behavior even on 32-bit-int hosts. * The tz library <ftp://elsie.nci.nih.gov/pub/> now has the best-practice behavior suggested above.

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Tzcode2005c.tar.gz and tzdata2005c.tar.gz
by Olson, Arthur David (NIH/NCI) Jan. 17, 2005

Jan. 17, 2005

The files... ftp://elsie.nci.nih.gov/pub/tzcode2005c.tar.gz ...and... ftp://elsie.nci.nih.gov/pub/tzdata2005c.tar.gz ...are now available; these incorporate the changes circulated last week on the time zone mailing list to get better results when mktime runs on a system where time_t is double, along with changes to the data files (most importantly to Paraguay). Next up on the schedule: have zic warn about links to links. --ado

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