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questions and comments on http://tycho.usno.navy.mil/tzones.html
by Paul Eggert Nov. 11, 1995

Nov. 11, 1995

Thanks for putting the USNO unofficial time zone info on the Web; it has helped me compose proposed patches for the public domain time zone history database at <ftp://elsie.nci.nih.gov/pub/tzdata95k.tar.gz>. After comparing the USNO data to other sources, I have some questions and comments. I'd appreciate any information you can send me to clear up the questions, especially pointers to other sources. The tzdata history database relies heavily on Thomas G. Shanks, The International Atlas (3rd edition), San Diego: ACS Publications (1991), a source that is now 4 years old, so some of the discrepancies noted below are undoubtedly because the time zones or daylight savings rules have changed recently. But I thought I'd tell you about the discrepancies just in case. <http://tycho.usno.navy.mil/tzones.html> (1995-11-11) says: Antarctica: -2 hours (Local summer -3 hours) Which part of Antarctica is that? I have the vague impression that different research stations in Antarctica use different local times. (The South Pole is the most interesting case, of course.) Armenia: +4 hours (Local summer +5 hours) Shanks has Armenia switching to +3 (+4 summer) in 1991. Perhaps they've switched back? Argentina western prov: -4 hours Shanks says Argentina has always had just one time zone. Azerbajian: +3 hours Shanks has Baku at +3 (+4 summer). Perhaps they've stopped using daylight savings time? Brazil Acre: -4 hours (Local summer -5 hours) Brazil Atlantic Islands: -1 hours (Local summer -2 hours) Brazil East: -3 hours (Local summer -1 hours) These must be typos. Here are proposed fixes. Brazil Acre: -5 hours (Local summer -4 hours) Brazil Atlantic Islands: -2 hours (Local summer -1 hours) Brazil East: -3 hours (Local summer -2 hours) Chatham Island: +12.75 hours (Local summer +13.75 hours) Do you have a source for when the transition to and from summer time takes place? Cocos (Keeling) Islands: ( hours (Local summer ) hours) This is a typo. The 1989 USNO listing has Cocos at +6.5 hours. Cook Islands: -10 hours Shanks has Cook at -9.5 during summer. The 1989 USNO listing had two entries for Cook, one at -10, the other at -10 (-9.5 summer) like Shanks. Equitorial Guinea: +1 hours This should be `Equatorial Guinea'. French Polynesia: -10 hours French Polynesia covers several time zones; e.g. I think the Marquesas and Gambier are part of French Polynesia, and they are at -9.5 and -9, respectively. Georgia: +4 hours Shanks says Georgia has summer time, but this may have changed with the rules change late last year (see _The Economist_, 1994-11-19, page 60). Is there a better source for this? Greenland Scoresbysun: -1 hours (Local summer 0 hours) This should be `Scoresbysund'. Guinea Bissau: - hours (Local summer 0 hours) This should be `0 hours', with no summer time. Kazakhstan: +6 hours (Local summer +7 hours) Shanks says Alma-Ata switched to +5 (+6 summer) in 1991. Perhaps they've switched back? Kiribati: +12 hours The country of Kiribati covers several time zones. Perhaps you could change `Kiribati' to `Tarawa'. Kwajalein: -12 hours In comp.risks 14.87 <http://catless.ncl.ac.uk/Risks/14.87.html#subj2> (1993-08-26), Peter Neumann writes that Kwajalein changed to +12 hours on 1993-08-20. Libya: +2 hours Shanks has Libya at +1 (summer +2). Mexico Baja Calif Norte: -8 hours (Local summer -7 hours) Shanks has Ensenada, southern Baja, at -8 all year. Mongolia: +8 hours Shanks says Mongolia has 3 time zones: +7 (+8 summer), +8 (+9 summer), and +9 (+10 summer). Namibia: +1 hours (Local summer +2 hours) Nicaragua: -6 hours (Local summer -5 hours) Shanks has Namibia at +2 all year, and Nicaragua at -6 all year. If these have changed recently, do you know when it changed, and what the transition times are? Russian Federation zone two: +4 hours (Local summer +5 hours) This must be a typo; it should be `+3 hours (Local summer +4 hours)'. Scotland: 0 hours Shanks and other sources have Scotland at +1 in summer. Tajikistan: +6 hours Shanks has Tajikistan at +5 (+6 summer). Perhaps they've switched? Tunisia: +1 hours Shanks has Tunisia at +2 in summer. Perhaps they've stopped using DST? Turkmenistan: +5 hours Shanks has Turkmenistan at +6 during summer. Perhaps they've stopped using DST? Ukraine: +2 hours (Local summer +3 hours) Ukraine has multiple time zones. _The Economist_ (1994-05-28, page 45) reports that Crimea switched to +3 (summer +4) last year. Uzbekistan: +5 hours Shanks has Tashkent at +5 (+6 summer). Perhaps they've stopped using daylight savings time?

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time zone sources on the Web
by Paul Eggert Nov. 6, 1995

Nov. 6, 1995

In the tz distribution, perhaps there could be an addition to README, or some new file, that lists useful Web references for time zones. Here is some possible text: The Web has several other sources for time zone and daylight savings data. Here are some recent links that may be of interest. Date and Time Gateway http://www.bsdi.com/date A text-based source for tables of current time throughout the world. Its point-and-click interface accesses a recent version of the tz data. Local Times Around the World http://www.hilink.com.au/times/ This text-based system contains links to local time servers throughout the world, and though the coverage is limited, the live data provide a nice way to check one's tables. World Time Zones http://tycho.usno.navy.mil/tzones.html US Naval Observatory data, used as the source for `usno1995'. Standard Time Zones of the World http://www.odci.gov/cia/publications/95fact/802389.gif [54 kB] http://www.odci.gov/cia/publications/95fact/802389h.gif [1317 kB] A static time zone map, available in both low-resolution and high-resolution versions. The quality is good, but the map does not indicate summer time, and parts of the data are a few years out of date. VIBE's World Map http://pathfinder.com/vibe/vibeworld An active time zone map. You can point to the map and find out what time it is at that location. The map and data are not as good as other sources.

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Re: Reentrant versions of localtime and gmtime.
by Joel.Tornatore＠Eng.Sun.COM Oct. 31, 1995

Oct. 31, 1995

## From eggert(a)twinsun.com Mon Oct 30 20:06:39 1995 ## ## Date: Mon, 30 Oct 1995 17:13:53 -0800 ## From: "J.T. Conklin" <jtc(a)cygnus.com> ## ## struct tm * ## + localtime_r(timep, res) ## + const time_t * const timep; ## + struct tm * tm; ## + { ## + tzset(); ## + localsub(timep, 0L, tm); ## + return tm; ## + } ## ## That isn't reentrant, since tzset() isn't reentrant. Solaris solves this problem with a mutex lock that is acquired by all functions, including the _r versions. joel

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Reentrant versions of localtime and gmtime.
by J.T. Conklin Oct. 30, 1995

Oct. 30, 1995

Thread-safe programming needs reentrant versions of some of the time functions. The following patch adds localtime_r and gmtime_r a'la Solaris (The Solaris manpage mentiones that these are taken from a POSIX draft, but I don't have a copy to double check). Although it is possible to write localtime and gmtime in terms of the new functions, I decided not to because they are so trival. The Solaris manpage also mentions ctime_r and asctime_r. I'll submit those later tonight. --jtc *** OLD/localtime.c Mon Oct 30 17:00:52 1995 --- localtime.c Mon Oct 30 17:03:48 1995 *************** *** 1026,1031 **** --- 1026,1041 ---- } struct tm * + localtime_r(timep, res) + const time_t * const timep; + struct tm * tm; + { + tzset(); + localsub(timep, 0L, tm); + return tm; + } + + struct tm * localtime(timep) const time_t * const timep; { *************** *** 1072,1077 **** --- 1082,1096 ---- #endif /* State Farm */ } #endif /* defined TM_ZONE */ + } + + struct tm * + gmtime_r(timep, tm) + const time_t * const timep; + struct tm * tm; + { + gmtsub(timep, 0L, tm); + return tm; } struct tm *

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Question about reentrant ctime and asctime
by J.T. Conklin Oct. 30, 1995

Oct. 30, 1995

In my previous message, I mentioned that I'd submit versions of asctime_r and ctime_r later this evening. However, I discovered that most systems declare these as: int asctime_r (const struct tm *, char *, int); int ctime_r (const time_t *, char *, int); while Solaris provides: char *asctime_r (const struct tm *, char *, int); char *ctime_r (const time_t *, char *, int); *AND* char *asctime_r (const struct tm *, char *) char *ctime_r (const time_t *, char *); Naturally I'd like to implement the interface standardized by whatever POSIX standard covers this (realtime?, threads?). If someone with the appropriate standards document could point out the correct interface, please let me know. --jtc

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Re: tz 8-bit-clean proposed patch
by ado Oct. 30, 1995

Oct. 30, 1995

The (slightly reformatted) "8-bit-clean proposed patch" and the "tz minor patch: US/Eastern -> America/New_York" have been incorporated into... -rw-r--r-- 1 ado 69206 Oct 30 10:40 tzcode95g.tar.gz -rw-r--r-- 1 ado 69838 Oct 30 10:40 tzdata95k.tar.gz in elsie.nci.nih.gov's ~ftp/pub directory, along with a snapshot of the USNO's latest data ("usno1995") and some other minor cleanups. --ado

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tz minor patch: US/Eastern -> America/New_York
by Paul Eggert Oct. 29, 1995

Oct. 29, 1995

Some tz comments refer to US/Eastern, but it is present only if the `backward' file is used. Here is a proposed patch. =================================================================== RCS file: RCS/Theory,v retrieving revision 1995.3 retrieving revision 1995.3.1.1 diff -c -r1995.3 -r1995.3.1.1 *** Theory 1993/11/22 20:23:18 1995.3 --- Theory 1995/10/30 01:50:47 1995.3.1.1 *************** *** 47,53 **** abbreviations are used. It was recognized that allowing the "TZ" environment variable to ! take on values such as "US/Eastern" might cause "old" programs (that expect "TZ" to have a certain form) to operate incorrectly; consideration was given to using some other environment variable (for example, "TIMEZONE") to hold the string used to generate the --- 47,53 ---- abbreviations are used. It was recognized that allowing the "TZ" environment variable to ! take on values such as "America/New_York" might cause "old" programs (that expect "TZ" to have a certain form) to operate incorrectly; consideration was given to using some other environment variable (for example, "TIMEZONE") to hold the string used to generate the =================================================================== RCS file: RCS/date.c,v retrieving revision 1995.3.1.1 retrieving revision 1995.3.1.2 diff -c -r1995.3.1.1 -r1995.3.1.2 *** date.c 1995/10/30 00:43:48 1995.3.1.1 --- date.c 1995/10/30 01:50:47 1995.3.1.2 *************** *** 207,215 **** if ((cp = strchr(value, '.')) != NULL) { /* ** Ensure that the failure of ! ** TZ=US/Eastern date 8712312359.60 ** doesn't get misdiagnosed. (It was ! ** TZ=US/Eastern date 8712311859.60 ** when the leap second was inserted.) ** The normal check won't work since ** the given time is valid in GMT. --- 207,215 ---- if ((cp = strchr(value, '.')) != NULL) { /* ** Ensure that the failure of ! ** TZ=America/New_York date 8712312359.60 ** doesn't get misdiagnosed. (It was ! ** TZ=America/New_York date 8712311859.60 ** when the leap second was inserted.) ** The normal check won't work since ** the given time is valid in GMT. =================================================================== RCS file: RCS/zic.8,v retrieving revision 1995.3 retrieving revision 1995.3.1.1 diff -c -r1995.3 -r1995.3.1.1 *** zic.8 1995/03/11 17:55:51 1995.3 --- zic.8 1995/10/30 01:50:47 1995.3.1.1 *************** *** 324,336 **** .nf .ti +.5i .if t .ta \w'Link\0\0'u +\w'LINK-FROM\0\0'u ! .if n .ta \w'Link\0\0'u +\w'US/Eastern\0\0'u Link LINK-FROM LINK-TO .sp For example: .sp .ti +.5i ! Link US/Eastern EST5EDT .sp .fi The --- 324,336 ---- .nf .ti +.5i .if t .ta \w'Link\0\0'u +\w'LINK-FROM\0\0'u ! .if n .ta \w'Link\0\0'u +\w'America/New_York\0\0'u Link LINK-FROM LINK-TO .sp For example: .sp .ti +.5i ! Link America/New_York US/Eastern .sp .fi The

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tz 8-bit-clean proposed patch
by Paul Eggert Oct. 29, 1995

Oct. 29, 1995

In a few places the tz code assumes that characters are nonnegative. The tz code uses `isascii' to avoid this problem sometimes, but not always, and anyway `isascii' isn't portable to some hosts that have strict ANSI or Posix checking turned on, since isascii is not required by either the C Standard or Posix. Here is a proposed patch that handles top-bit-on characters correctly in all the places where I found this problem. The patch is portable to hosts that don't define isascii. The proposed patch also removes a few unnecessary tests, and changes one call to ciequal to invoke strcmp, since the argument string has no alphabetic characters in it. =================================================================== RCS file: RCS/private.h,v retrieving revision 1995.3 retrieving revision 1995.3.1.1 diff -c -r1995.3 -r1995.3.1.1 *** private.h 1995/03/11 17:55:53 1995.3 --- private.h 1995/10/30 00:43:48 1995.3.1.1 *************** *** 47,53 **** #include "sys/types.h" /* for time_t */ #include "stdio.h" - #include "ctype.h" #include "errno.h" #include "string.h" #include "limits.h" /* for CHAR_BIT */ --- 47,52 ---- *************** *** 66,71 **** --- 65,73 ---- #define R_OK 4 #endif /* !defined R_OK */ #endif /* !(HAVE_UNISTD_H - 0) */ + + /* Unlike <ctype.h>'s isdigit, this also works if c < 0 | c > UCHAR_MAX. */ + #define is_digit(c) ((unsigned)(c) - '0' <= 9) /* ** Workarounds for compilers/systems. =================================================================== RCS file: RCS/date.c,v retrieving revision 1995.3 retrieving revision 1995.3.1.1 diff -c -r1995.3 -r1995.3.1.1 *** date.c 1995/03/11 17:55:47 1995.3 --- date.c 1995/10/30 00:43:48 1995.3.1.1 *************** *** 459,465 **** nondigit(cp) register const char * cp; { ! while (isdigit(*cp)) ++cp; return cp; } --- 459,465 ---- nondigit(cp) register const char * cp; { ! while (is_digit(*cp)) ++cp; return cp; } *************** *** 592,598 **** dotp = strchr(value, '.'); for (cp = value; *cp != '\0'; ++cp) ! if (!isdigit(*cp) && cp != dotp) wildinput("time", value, "contains a nondigit"); if (dotp == NULL) --- 592,598 ---- dotp = strchr(value, '.'); for (cp = value; *cp != '\0'; ++cp) ! if (!is_digit(*cp) && cp != dotp) wildinput("time", value, "contains a nondigit"); if (dotp == NULL) =================================================================== RCS file: RCS/localtime.c,v retrieving revision 1995.6 retrieving revision 1995.6.1.1 diff -c -r1995.6 -r1995.6.1.1 *** localtime.c 1995/10/28 16:09:02 1995.6 --- localtime.c 1995/10/30 00:43:48 1995.6.1.1 *************** *** 415,421 **** { register char c; ! while ((c = *strp) != '\0' && !isdigit(c) && c != ',' && c != '-' && c != '+') ++strp; return strp; --- 415,421 ---- { register char c; ! while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' && c != '+') ++strp; return strp; *************** *** 438,452 **** register char c; register int num; ! if (strp == NULL || !isdigit(*strp)) return NULL; num = 0; ! while ((c = *strp) != '\0' && isdigit(c)) { num = num * 10 + (c - '0'); if (num > max) return NULL; /* illegal value */ ! ++strp; ! } if (num < min) return NULL; /* illegal value */ *nump = num; --- 438,452 ---- register char c; register int num; ! if (strp == NULL || !is_digit(c = *strp)) return NULL; num = 0; ! do { num = num * 10 + (c - '0'); if (num > max) return NULL; /* illegal value */ ! c = *++strp; ! } while (is_digit(c)); if (num < min) return NULL; /* illegal value */ *nump = num; *************** *** 508,521 **** register const char * strp; long * const offsetp; { ! register int neg; if (*strp == '-') { neg = 1; ++strp; ! } else if (isdigit(*strp) || *strp++ == '+') ! neg = 0; ! else return NULL; /* illegal offset */ strp = getsecs(strp, offsetp); if (strp == NULL) return NULL; /* illegal time */ --- 508,520 ---- register const char * strp; long * const offsetp; { ! register int neg = 0; if (*strp == '-') { neg = 1; ++strp; ! } else if (*strp == '+') ! ++strp; strp = getsecs(strp, offsetp); if (strp == NULL) return NULL; /* illegal time */ *************** *** 560,566 **** if (*strp++ != '.') return NULL; strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1); ! } else if (isdigit(*strp)) { /* ** Day of year. */ --- 559,565 ---- if (*strp++ != '.') return NULL; strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1); ! } else if (is_digit(*strp)) { /* ** Day of year. */ =================================================================== RCS file: RCS/scheck.c,v retrieving revision 1994.8 retrieving revision 1994.8.1.1 diff -c -r1994.8 -r1994.8.1.1 *** scheck.c 1994/12/09 04:33:18 1994.8 --- scheck.c 1995/10/30 00:43:48 1994.8.1.1 *************** *** 42,48 **** *tp++ = '*'; if (*fp == '*') ++fp; ! while (isascii(*fp) && isdigit(*fp)) *tp++ = *fp++; if (*fp == 'l' || *fp == 'h') *tp++ = *fp++; --- 42,48 ---- *tp++ = '*'; if (*fp == '*') ++fp; ! while (is_digit(*fp)) *tp++ = *fp++; if (*fp == 'l' || *fp == 'h') *tp++ = *fp++; =================================================================== RCS file: RCS/zic.c,v retrieving revision 1995.6 retrieving revision 1995.6.1.1 diff -c -r1995.6 -r1995.6.1.1 *** zic.c 1995/10/28 20:51:12 1995.6 --- zic.c 1995/10/30 00:43:48 1995.6.1.1 *************** *** 10,15 **** --- 10,28 ---- #include "sys/stat.h" /* for umask manifest constants */ #endif /* defined unix */ + /* + ** On some ancient hosts, predicates like `isspace(C)' are defined + ** only if isascii(C) || C == EOF. Modern hosts obey the C Standard, + ** which says they are defined only if C == (unsigned char)C || C == EOF. + ** Neither the C Standard nor Posix require that `isascii' exist. + ** For portability, we check both ancient and modern requirements. + ** If isascii is not defined, the isascii check succeeds trivially. + */ + #include "ctype.h" + #ifndef isascii + #define isascii(x) 1 + #endif + struct rule { const char * r_filename; int r_linenum; *************** *** 721,727 **** while (fields[nfields] != NULL) { static char nada; ! if (ciequal(fields[nfields], "-")) fields[nfields] = &nada; ++nfields; } --- 734,740 ---- while (fields[nfields] != NULL) { static char nada; ! if (strcmp(fields[nfields], "-") == 0) fields[nfields] = &nada; ++nfields; } *************** *** 1702,1709 **** static int lowerit(a) ! const int a; { return (isascii(a) && isupper(a)) ? tolower(a) : a; } --- 1715,1723 ---- static int lowerit(a) ! int a; { + a = (unsigned char)a; return (isascii(a) && isupper(a)) ? tolower(a) : a; } *************** *** 1775,1781 **** emalloc((int) ((strlen(cp) + 1) * sizeof *array)); nsubs = 0; for ( ; ; ) { ! while (isascii(*cp) && isspace(*cp)) ++cp; if (*cp == '\0' || *cp == '#') break; --- 1789,1795 ---- emalloc((int) ((strlen(cp) + 1) * sizeof *array)); nsubs = 0; for ( ; ; ) { ! while (isascii(*cp) && isspace((unsigned char)*cp)) ++cp; if (*cp == '\0' || *cp == '#') break; *************** *** 1788,1795 **** ++dp; else error("Odd number of quotation marks"); } while (*cp != '\0' && *cp != '#' && ! (!isascii(*cp) || !isspace(*cp))); ! if (isascii(*cp) && isspace(*cp)) ++cp; *dp = '\0'; } --- 1802,1809 ---- ++dp; else error("Odd number of quotation marks"); } while (*cp != '\0' && *cp != '#' && ! (!isascii(*cp) || !isspace((unsigned char)*cp))); ! if (isascii(*cp) && isspace((unsigned char)*cp)) ++cp; *dp = '\0'; } *************** *** 1952,1959 **** /* ** DOS drive specifier? */ ! if (strlen(name) == 2 && isascii(name[0]) && ! isalpha(name[0]) && name[1] == ':') { *cp = '/'; continue; } --- 1966,1973 ---- /* ** DOS drive specifier? */ ! if (isalpha((unsigned char)name[0]) ! && name[1] == ':' && !name[2]) { *cp = '/'; continue; }

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United States Naval Observatory time zone data available via browsers
by ado Oct. 28, 1995

Oct. 28, 1995

The URL is http://tycho.usno.navy.mil/tzones.html --ado

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tzcode95f.tar.gz and tzdata95j.tar.gz
by ado Oct. 28, 1995

Oct. 28, 1995

These new files... -rw-r--r-- 1 ado 65981 Oct 28 16:57 tzcode95f.tar.gz -rw-r--r-- 1 ado 69781 Oct 28 16:57 tzdata95j.tar.gz ...are available by anonymous ftp from elsie.nci.nih.gov (165.112.73.1) in the ~ftp/pub directory. The files incorporate European cleanups circulated earlier on the time zone mailing list; they also provide support for 64-bit time_t's and optimization in localtime.c --ado

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