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postgres/src/timezone/pgtz.c
Bruce Momjian 4550c1e519 More macro cleanups for date/time.
2005-05-23 21:54:02 +00:00

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/*-------------------------------------------------------------------------
*
* pgtz.c
* Timezone Library Integration Functions
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.31 2005/05/23 21:54:02 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#define NO_REDEFINE_TIMEFUNCS
#include "postgres.h"
#include <ctype.h>
#include <sys/stat.h>
#include <time.h>
#include "miscadmin.h"
#include "pgtime.h"
#include "pgtz.h"
#include "storage/fd.h"
#include "tzfile.h"
#include "utils/datetime.h"
#include "utils/elog.h"
#include "utils/guc.h"
#include "utils/hsearch.h"
/* Current global timezone */
pg_tz *global_timezone = NULL;
static char tzdir[MAXPGPATH];
static int done_tzdir = 0;
static const char *identify_system_timezone(void);
static const char *select_default_timezone(void);
static bool set_global_timezone(const char *tzname);
/*
* Return full pathname of timezone data directory
*/
char *
pg_TZDIR(void)
{
if (done_tzdir)
return tzdir;
get_share_path(my_exec_path, tzdir);
strcat(tzdir, "/timezone");
done_tzdir = 1;
return tzdir;
}
/*
* The following block of code attempts to determine which timezone in our
* timezone database is the best match for the active system timezone.
*
* On most systems, we rely on trying to match the observable behavior of
* the C library's localtime() function. The database zone that matches
* furthest into the past is the one to use. Often there will be several
* zones with identical rankings (since the zic database assigns multiple
* names to many zones). We break ties arbitrarily by preferring shorter,
* then alphabetically earlier zone names.
*
* Win32's native knowledge about timezones appears to be too incomplete
* and too different from the zic database for the above matching strategy
* to be of any use. But there is just a limited number of timezones
* available, so we can rely on a handmade mapping table instead.
*/
#ifndef WIN32
#define T_DAY ((time_t) (60*60*24))
#define T_WEEK ((time_t) (60*60*24*7))
#define T_MONTH ((time_t) (60*60*24*31))
#define MAX_TEST_TIMES (52*100) /* 100 years, or 1904..2004 */
struct tztry
{
int n_test_times;
time_t test_times[MAX_TEST_TIMES];
};
static void scan_available_timezones(char *tzdir, char *tzdirsub,
struct tztry * tt,
int *bestscore, char *bestzonename);
/*
* Get GMT offset from a system struct tm
*/
static int
get_timezone_offset(struct tm * tm)
{
#if defined(HAVE_STRUCT_TM_TM_ZONE)
return tm->tm_gmtoff;
#elif defined(HAVE_INT_TIMEZONE)
return -TIMEZONE_GLOBAL;
#else
#error No way to determine TZ? Can this happen?
#endif
}
/*
* Convenience subroutine to convert y/m/d to time_t (NOT pg_time_t)
*/
static time_t
build_time_t(int year, int month, int day)
{
struct tm tm;
memset(&tm, 0, sizeof(tm));
tm.tm_mday = day;
tm.tm_mon = month - 1;
tm.tm_year = year - 1900;
return mktime(&tm);
}
/*
* Does a system tm value match one we computed ourselves?
*/
static bool
compare_tm(struct tm * s, struct pg_tm * p)
{
if (s->tm_sec != p->tm_sec ||
s->tm_min != p->tm_min ||
s->tm_hour != p->tm_hour ||
s->tm_mday != p->tm_mday ||
s->tm_mon != p->tm_mon ||
s->tm_year != p->tm_year ||
s->tm_wday != p->tm_wday ||
s->tm_yday != p->tm_yday ||
s->tm_isdst != p->tm_isdst)
return false;
return true;
}
/*
* See how well a specific timezone setting matches the system behavior
*
* We score a timezone setting according to the number of test times it
* matches. (The test times are ordered later-to-earlier, but this routine
* doesn't actually know that; it just scans until the first non-match.)
*
* We return -1 for a completely unusable setting; this is worse than the
* score of zero for a setting that works but matches not even the first
* test time.
*/
static int
score_timezone(const char *tzname, struct tztry * tt)
{
int i;
pg_time_t pgtt;
struct tm *systm;
struct pg_tm *pgtm;
char cbuf[TZ_STRLEN_MAX + 1];
pg_tz *tz;
tz = pg_tzset(tzname);
if (!tz)
return -1; /* can't handle the TZ name at all */
/* Reject if leap seconds involved */
if (!tz_acceptable(tz))
{
elog(DEBUG4, "Reject TZ \"%s\": uses leap seconds", tzname);
return -1;
}
/* Check for match at all the test times */
for (i = 0; i < tt->n_test_times; i++)
{
pgtt = (pg_time_t) (tt->test_times[i]);
pgtm = pg_localtime(&pgtt, tz);
if (!pgtm)
return -1; /* probably shouldn't happen */
systm = localtime(&(tt->test_times[i]));
if (!systm)
{
elog(DEBUG4, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s, system had no data",
tzname, i, (long) pgtt,
pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
pgtm->tm_isdst ? "dst" : "std");
return i;
}
if (!compare_tm(systm, pgtm))
{
elog(DEBUG4, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s versus %04d-%02d-%02d %02d:%02d:%02d %s",
tzname, i, (long) pgtt,
pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
pgtm->tm_isdst ? "dst" : "std",
systm->tm_year + 1900, systm->tm_mon + 1, systm->tm_mday,
systm->tm_hour, systm->tm_min, systm->tm_sec,
systm->tm_isdst ? "dst" : "std");
return i;
}
if (systm->tm_isdst >= 0)
{
/* Check match of zone names, too */
if (pgtm->tm_zone == NULL)
return -1; /* probably shouldn't happen */
memset(cbuf, 0, sizeof(cbuf));
strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm); /* zone abbr */
if (strcmp(cbuf, pgtm->tm_zone) != 0)
{
elog(DEBUG4, "TZ \"%s\" scores %d: at %ld \"%s\" versus \"%s\"",
tzname, i, (long) pgtt,
pgtm->tm_zone, cbuf);
return i;
}
}
}
elog(DEBUG4, "TZ \"%s\" gets max score %d", tzname, i);
return i;
}
/*
* Try to identify a timezone name (in our terminology) that best matches the
* observed behavior of the system timezone library. We cannot assume that
* the system TZ environment setting (if indeed there is one) matches our
* terminology, so we ignore it and just look at what localtime() returns.
*/
static const char *
identify_system_timezone(void)
{
static char resultbuf[TZ_STRLEN_MAX + 1];
time_t tnow;
time_t t;
struct tztry tt;
struct tm *tm;
int bestscore;
char tmptzdir[MAXPGPATH];
int std_ofs;
char std_zone_name[TZ_STRLEN_MAX + 1],
dst_zone_name[TZ_STRLEN_MAX + 1];
char cbuf[TZ_STRLEN_MAX + 1];
/* Initialize OS timezone library */
tzset();
/*
* Set up the list of dates to be probed to see how well our timezone
* matches the system zone. We first probe January and July of 2004;
* this serves to quickly eliminate the vast majority of the TZ
* database entries. If those dates match, we probe every week from
* 2004 backwards to late 1904. (Weekly resolution is good enough to
* identify DST transition rules, since everybody switches on
* Sundays.) The further back the zone matches, the better we score
* it. This may seem like a rather random way of doing things, but
* experience has shown that system-supplied timezone definitions are
* likely to have DST behavior that is right for the recent past and
* not so accurate further back. Scoring in this way allows us to
* recognize zones that have some commonality with the zic database,
* without insisting on exact match. (Note: we probe Thursdays, not
* Sundays, to avoid triggering DST-transition bugs in localtime
* itself.)
*/
tt.n_test_times = 0;
tt.test_times[tt.n_test_times++] = build_time_t(2004, 1, 15);
tt.test_times[tt.n_test_times++] = t = build_time_t(2004, 7, 15);
while (tt.n_test_times < MAX_TEST_TIMES)
{
t -= T_WEEK;
tt.test_times[tt.n_test_times++] = t;
}
/* Search for the best-matching timezone file */
strcpy(tmptzdir, pg_TZDIR());
bestscore = -1;
resultbuf[0] = '\0';
scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1,
&tt,
&bestscore, resultbuf);
if (bestscore > 0)
return resultbuf;
/*
* Couldn't find a match in the database, so next we try constructed
* zone names (like "PST8PDT").
*
* First we need to determine the names of the local standard and
* daylight zones. The idea here is to scan forward from today until
* we have seen both zones, if both are in use.
*/
memset(std_zone_name, 0, sizeof(std_zone_name));
memset(dst_zone_name, 0, sizeof(dst_zone_name));
std_ofs = 0;
tnow = time(NULL);
/*
* Round back to a GMT midnight so results don't depend on local time
* of day
*/
tnow -= (tnow % T_DAY);
/*
* We have to look a little further ahead than one year, in case today
* is just past a DST boundary that falls earlier in the year than the
* next similar boundary. Arbitrarily scan up to 14 months.
*/
for (t = tnow; t <= tnow + T_MONTH * 14; t += T_MONTH)
{
tm = localtime(&t);
if (!tm)
continue;
if (tm->tm_isdst < 0)
continue;
if (tm->tm_isdst == 0 && std_zone_name[0] == '\0')
{
/* found STD zone */
memset(cbuf, 0, sizeof(cbuf));
strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
strcpy(std_zone_name, cbuf);
std_ofs = get_timezone_offset(tm);
}
if (tm->tm_isdst > 0 && dst_zone_name[0] == '\0')
{
/* found DST zone */
memset(cbuf, 0, sizeof(cbuf));
strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
strcpy(dst_zone_name, cbuf);
}
/* Done if found both */
if (std_zone_name[0] && dst_zone_name[0])
break;
}
/* We should have found a STD zone name by now... */
if (std_zone_name[0] == '\0')
{
ereport(LOG,
(errmsg("unable to determine system timezone, defaulting to \"%s\"", "GMT"),
errhint("You can specify the correct timezone in postgresql.conf.")));
return NULL; /* go to GMT */
}
/* If we found DST then try STD<ofs>DST */
if (dst_zone_name[0] != '\0')
{
snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
std_zone_name, -std_ofs / 3600, dst_zone_name);
if (score_timezone(resultbuf, &tt) > 0)
return resultbuf;
}
/* Try just the STD timezone (works for GMT at least) */
strcpy(resultbuf, std_zone_name);
if (score_timezone(resultbuf, &tt) > 0)
return resultbuf;
/* Try STD<ofs> */
snprintf(resultbuf, sizeof(resultbuf), "%s%d",
std_zone_name, -std_ofs / 3600);
if (score_timezone(resultbuf, &tt) > 0)
return resultbuf;
/*
* Did not find the timezone. Fallback to use a GMT zone. Note that
* the zic timezone database names the GMT-offset zones in POSIX
* style: plus is west of Greenwich. It's unfortunate that this is
* opposite of SQL conventions. Should we therefore change the names?
* Probably not...
*/
snprintf(resultbuf, sizeof(resultbuf), "Etc/GMT%s%d",
(-std_ofs > 0) ? "+" : "", -std_ofs / 3600);
ereport(LOG,
(errmsg("could not recognize system timezone, defaulting to \"%s\"",
resultbuf),
errhint("You can specify the correct timezone in postgresql.conf.")));
return resultbuf;
}
/*
* Recursively scan the timezone database looking for the best match to
* the system timezone behavior.
*
* tzdir points to a buffer of size MAXPGPATH. On entry, it holds the
* pathname of a directory containing TZ files. We internally modify it
* to hold pathnames of sub-directories and files, but must restore it
* to its original contents before exit.
*
* tzdirsub points to the part of tzdir that represents the subfile name
* (ie, tzdir + the original directory name length, plus one for the
* first added '/').
*
* tt tells about the system timezone behavior we need to match.
*
* *bestscore and *bestzonename on entry hold the best score found so far
* and the name of the best zone. We overwrite them if we find a better
* score. bestzonename must be a buffer of length TZ_STRLEN_MAX + 1.
*/
static void
scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry * tt,
int *bestscore, char *bestzonename)
{
int tzdir_orig_len = strlen(tzdir);
DIR *dirdesc;
dirdesc = AllocateDir(tzdir);
if (!dirdesc)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open directory \"%s\": %m", tzdir)));
return;
}
for (;;)
{
struct dirent *direntry;
struct stat statbuf;
errno = 0;
direntry = readdir(dirdesc);
if (!direntry)
{
if (errno)
ereport(LOG,
(errcode_for_file_access(),
errmsg("error reading directory: %m")));
break;
}
/* Ignore . and .., plus any other "hidden" files */
if (direntry->d_name[0] == '.')
continue;
snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
"/%s", direntry->d_name);
if (stat(tzdir, &statbuf) != 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not stat \"%s\": %m", tzdir)));
continue;
}
if (S_ISDIR(statbuf.st_mode))
{
/* Recurse into subdirectory */
scan_available_timezones(tzdir, tzdirsub, tt,
bestscore, bestzonename);
}
else
{
/* Load and test this file */
int score = score_timezone(tzdirsub, tt);
if (score > *bestscore)
{
*bestscore = score;
StrNCpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
}
else if (score == *bestscore)
{
/* Consider how to break a tie */
if (strlen(tzdirsub) < strlen(bestzonename) ||
(strlen(tzdirsub) == strlen(bestzonename) &&
strcmp(tzdirsub, bestzonename) < 0))
StrNCpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
}
}
}
FreeDir(dirdesc);
/* Restore tzdir */
tzdir[tzdir_orig_len] = '\0';
}
#else /* WIN32 */
static const struct
{
const char *stdname; /* Windows name of standard timezone */
const char *dstname; /* Windows name of daylight timezone */
const char *pgtzname; /* Name of pgsql timezone to map to */
} win32_tzmap[] =
{
/*
* This list was built from the contents of the registry at
* HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
* NT\CurrentVersion\Time Zones on Windows XP Professional SP1
*
* The zones have been matched to zic timezones by looking at the cities
* listed in the win32 display name (in the comment here) in most
* cases.
*/
{
"Afghanistan Standard Time", "Afghanistan Daylight Time",
"Asia/Kabul"
}, /* (GMT+04:30) Kabul */
{
"Alaskan Standard Time", "Alaskan Daylight Time",
"US/Alaska"
}, /* (GMT-09:00) Alaska */
{
"Arab Standard Time", "Arab Daylight Time",
"Asia/Kuwait"
}, /* (GMT+03:00) Kuwait, Riyadh */
{
"Arabian Standard Time", "Arabian Daylight Time",
"Asia/Muscat"
}, /* (GMT+04:00) Abu Dhabi, Muscat */
{
"Arabic Standard Time", "Arabic Daylight Time",
"Asia/Baghdad"
}, /* (GMT+03:00) Baghdad */
{
"Atlantic Standard Time", "Atlantic Daylight Time",
"Canada/Atlantic"
}, /* (GMT-04:00) Atlantic Time (Canada) */
{
"AUS Central Standard Time", "AUS Central Daylight Time",
"Australia/Darwin"
}, /* (GMT+09:30) Darwin */
{
"AUS Eastern Standard Time", "AUS Eastern Daylight Time",
"Australia/Canberra"
}, /* (GMT+10:00) Canberra, Melbourne, Sydney */
{
"Azores Standard Time", "Azores Daylight Time",
"Atlantic/Azores"
}, /* (GMT-01:00) Azores */
{
"Canada Central Standard Time", "Canada Central Daylight Time",
"Canada/Saskatchewan"
}, /* (GMT-06:00) Saskatchewan */
{
"Cape Verde Standard Time", "Cape Verde Daylight Time",
"Atlantic/Cape_Verde"
}, /* (GMT-01:00) Cape Verde Is. */
{
"Caucasus Standard Time", "Caucasus Daylight Time",
"Asia/Baku"
}, /* (GMT+04:00) Baku, Tbilisi, Yerevan */
{
"Cen. Australia Standard Time", "Cen. Australia Daylight Time",
"Australia/Adelaide"
}, /* (GMT+09:30) Adelaide */
{
"Central America Standard Time", "Central America Daylight Time",
"CST6CDT"
}, /* (GMT-06:00) Central America */
{
"Central Asia Standard Time", "Central Asia Daylight Time",
"Asia/Dhaka"
}, /* (GMT+06:00) Astana, Dhaka */
{
"Central Europe Standard Time", "Central Europe Daylight Time",
"Europe/Belgrade"
}, /* (GMT+01:00) Belgrade, Bratislava,
* Budapest, Ljubljana, Prague */
{
"Central European Standard Time", "Central European Daylight Time",
"Europe/Sarajevo"
}, /* (GMT+01:00) Sarajevo, Skopje, Warsaw,
* Zagreb */
{
"Central Pacific Standard Time", "Central Pacific Daylight Time",
"Pacific/Noumea"
}, /* (GMT+11:00) Magadan, Solomon Is., New
* Caledonia */
{
"Central Standard Time", "Central Daylight Time",
"US/Central"
}, /* (GMT-06:00) Central Time (US & Canada) */
{
"China Standard Time", "China Daylight Time",
"Asia/Hong_Kong"
}, /* (GMT+08:00) Beijing, Chongqing, Hong
* Kong, Urumqi */
{
"Dateline Standard Time", "Dateline Daylight Time",
"Etc/GMT+12"
}, /* (GMT-12:00) International Date Line
* West */
{
"E. Africa Standard Time", "E. Africa Daylight Time",
"Africa/Nairobi"
}, /* (GMT+03:00) Nairobi */
{
"E. Australia Standard Time", "E. Australia Daylight Time",
"Australia/Brisbane"
}, /* (GMT+10:00) Brisbane */
{
"E. Europe Standard Time", "E. Europe Daylight Time",
"Europe/Bucharest"
}, /* (GMT+02:00) Bucharest */
{
"E. South America Standard Time", "E. South America Daylight Time",
"America/Araguaina"
}, /* (GMT-03:00) Brasilia */
{
"Eastern Standard Time", "Eastern Daylight Time",
"US/Eastern"
}, /* (GMT-05:00) Eastern Time (US & Canada) */
{
"Egypt Standard Time", "Egypt Daylight Time",
"Africa/Cairo"
}, /* (GMT+02:00) Cairo */
{
"Ekaterinburg Standard Time", "Ekaterinburg Daylight Time",
"Asia/Yekaterinburg"
}, /* (GMT+05:00) Ekaterinburg */
{
"Fiji Standard Time", "Fiji Daylight Time",
"Pacific/Fiji"
}, /* (GMT+12:00) Fiji, Kamchatka, Marshall
* Is. */
{
"FLE Standard Time", "FLE Daylight Time",
"Europe/Helsinki"
}, /* (GMT+02:00) Helsinki, Kyiv, Riga,
* Sofia, Tallinn, Vilnius */
{
"GMT Standard Time", "GMT Daylight Time",
"Europe/Dublin"
}, /* (GMT) Greenwich Mean Time : Dublin,
* Edinburgh, Lisbon, London */
{
"Greenland Standard Time", "Greenland Daylight Time",
"America/Godthab"
}, /* (GMT-03:00) Greenland */
{
"Greenwich Standard Time", "Greenwich Daylight Time",
"Africa/Casablanca"
}, /* (GMT) Casablanca, Monrovia */
{
"GTB Standard Time", "GTB Daylight Time",
"Europe/Athens"
}, /* (GMT+02:00) Athens, Istanbul, Minsk */
{
"Hawaiian Standard Time", "Hawaiian Daylight Time",
"US/Hawaii"
}, /* (GMT-10:00) Hawaii */
{
"India Standard Time", "India Daylight Time",
"Asia/Calcutta"
}, /* (GMT+05:30) Chennai, Kolkata, Mumbai,
* New Delhi */
{
"Iran Standard Time", "Iran Daylight Time",
"Asia/Tehran"
}, /* (GMT+03:30) Tehran */
{
"Jerusalem Standard Time", "Jerusalem Daylight Time",
"Asia/Jerusalem"
}, /* (GMT+02:00) Jerusalem */
{
"Korea Standard Time", "Korea Daylight Time",
"Asia/Seoul"
}, /* (GMT+09:00) Seoul */
{
"Mexico Standard Time", "Mexico Daylight Time",
"America/Mexico_City"
}, /* (GMT-06:00) Guadalajara, Mexico City,
* Monterrey */
{
"Mexico Standard Time", "Mexico Daylight Time",
"America/La_Paz"
}, /* (GMT-07:00) Chihuahua, La Paz, Mazatlan */
{
"Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
"Atlantic/South_Georgia"
}, /* (GMT-02:00) Mid-Atlantic */
{
"Mountain Standard Time", "Mountain Daylight Time",
"US/Mountain"
}, /* (GMT-07:00) Mountain Time (US & Canada) */
{
"Myanmar Standard Time", "Myanmar Daylight Time",
"Asia/Rangoon"
}, /* (GMT+06:30) Rangoon */
{
"N. Central Asia Standard Time", "N. Central Asia Daylight Time",
"Asia/Almaty"
}, /* (GMT+06:00) Almaty, Novosibirsk */
{
"Nepal Standard Time", "Nepal Daylight Time",
"Asia/Katmandu"
}, /* (GMT+05:45) Kathmandu */
{
"New Zealand Standard Time", "New Zealand Daylight Time",
"Pacific/Auckland"
}, /* (GMT+12:00) Auckland, Wellington */
{
"Newfoundland Standard Time", "Newfoundland Daylight Time",
"Canada/Newfoundland"
}, /* (GMT-03:30) Newfoundland */
{
"North Asia East Standard Time", "North Asia East Daylight Time",
"Asia/Irkutsk"
}, /* (GMT+08:00) Irkutsk, Ulaan Bataar */
{
"North Asia Standard Time", "North Asia Daylight Time",
"Asia/Krasnoyarsk"
}, /* (GMT+07:00) Krasnoyarsk */
{
"Pacific SA Standard Time", "Pacific SA Daylight Time",
"America/Santiago"
}, /* (GMT-04:00) Santiago */
{
"Pacific Standard Time", "Pacific Daylight Time",
"US/Pacific"
}, /* (GMT-08:00) Pacific Time (US & Canada);
* Tijuana */
{
"Romance Standard Time", "Romance Daylight Time",
"Europe/Brussels"
}, /* (GMT+01:00) Brussels, Copenhagen,
* Madrid, Paris */
{
"Russian Standard Time", "Russian Daylight Time",
"Europe/Moscow"
}, /* (GMT+03:00) Moscow, St. Petersburg,
* Volgograd */
{
"SA Eastern Standard Time", "SA Eastern Daylight Time",
"America/Buenos_Aires"
}, /* (GMT-03:00) Buenos Aires, Georgetown */
{
"SA Pacific Standard Time", "SA Pacific Daylight Time",
"America/Bogota"
}, /* (GMT-05:00) Bogota, Lima, Quito */
{
"SA Western Standard Time", "SA Western Daylight Time",
"America/Caracas"
}, /* (GMT-04:00) Caracas, La Paz */
{
"Samoa Standard Time", "Samoa Daylight Time",
"Pacific/Midway"
}, /* (GMT-11:00) Midway Island, Samoa */
{
"SE Asia Standard Time", "SE Asia Daylight Time",
"Asia/Bangkok"
}, /* (GMT+07:00) Bangkok, Hanoi, Jakarta */
{
"Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
"Asia/Kuala_Lumpur"
}, /* (GMT+08:00) Kuala Lumpur, Singapore */
{
"South Africa Standard Time", "South Africa Daylight Time",
"Africa/Harare"
}, /* (GMT+02:00) Harare, Pretoria */
{
"Sri Lanka Standard Time", "Sri Lanka Daylight Time",
"Asia/Colombo"
}, /* (GMT+06:00) Sri Jayawardenepura */
{
"Taipei Standard Time", "Taipei Daylight Time",
"Asia/Taipei"
}, /* (GMT+08:00) Taipei */
{
"Tasmania Standard Time", "Tasmania Daylight Time",
"Australia/Hobart"
}, /* (GMT+10:00) Hobart */
{
"Tokyo Standard Time", "Tokyo Daylight Time",
"Asia/Tokyo"
}, /* (GMT+09:00) Osaka, Sapporo, Tokyo */
{
"Tonga Standard Time", "Tonga Daylight Time",
"Pacific/Tongatapu"
}, /* (GMT+13:00) Nuku'alofa */
{
"US Eastern Standard Time", "US Eastern Daylight Time",
"US/Eastern"
}, /* (GMT-05:00) Indiana (East) */
{
"US Mountain Standard Time", "US Mountain Daylight Time",
"US/Arizona"
}, /* (GMT-07:00) Arizona */
{
"Vladivostok Standard Time", "Vladivostok Daylight Time",
"Asia/Vladivostok"
}, /* (GMT+10:00) Vladivostok */
{
"W. Australia Standard Time", "W. Australia Daylight Time",
"Australia/Perth"
}, /* (GMT+08:00) Perth */
/* {"W. Central Africa Standard Time", "W. Central Africa Daylight Time",
* * ""}, Could not find a match for this one. Excluded for now. *//* (
* G MT+01:00) West Central Africa */
{
"W. Europe Standard Time", "W. Europe Daylight Time",
"CET"
}, /* (GMT+01:00) Amsterdam, Berlin, Bern,
* Rome, Stockholm, Vienna */
{
"West Asia Standard Time", "West Asia Daylight Time",
"Asia/Karachi"
}, /* (GMT+05:00) Islamabad, Karachi,
* Tashkent */
{
"West Pacific Standard Time", "West Pacific Daylight Time",
"Pacific/Guam"
}, /* (GMT+10:00) Guam, Port Moresby */
{
"Yakutsk Standard Time", "Yakutsk Daylight Time",
"Asia/Yakutsk"
}, /* (GMT+09:00) Yakutsk */
{
NULL, NULL, NULL
}
};
static const char *
identify_system_timezone(void)
{
int i;
char tzname[128];
char localtzname[256];
time_t t = time(NULL);
struct tm *tm = localtime(&t);
HKEY rootKey;
int idx;
if (!tm)
{
ereport(WARNING,
(errmsg_internal("could not determine current date/time: localtime failed")));
return NULL;
}
memset(tzname, 0, sizeof(tzname));
strftime(tzname, sizeof(tzname) - 1, "%Z", tm);
for (i = 0; win32_tzmap[i].stdname != NULL; i++)
{
if (strcmp(tzname, win32_tzmap[i].stdname) == 0 ||
strcmp(tzname, win32_tzmap[i].dstname) == 0)
{
elog(DEBUG4, "TZ \"%s\" matches Windows timezone \"%s\"",
win32_tzmap[i].pgtzname, tzname);
return win32_tzmap[i].pgtzname;
}
}
/*
* Localized Windows versions return localized names for the
* timezone. Scan the registry to find the English name,
* and then try matching against our table again.
*/
memset(localtzname, 0, sizeof(localtzname));
if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
0,
KEY_READ,
&rootKey) != ERROR_SUCCESS)
{
ereport(WARNING,
(errmsg_internal("could not open registry key to identify Windows timezone: %i", (int)GetLastError())));
return NULL;
}
for (idx = 0; ; idx++)
{
char keyname[256];
char zonename[256];
DWORD namesize;
FILETIME lastwrite;
HKEY key;
LONG r;
memset(keyname, 0, sizeof(keyname));
namesize = sizeof(keyname);
if ((r=RegEnumKeyEx(rootKey,
idx,
keyname,
&namesize,
NULL,
NULL,
NULL,
&lastwrite)) != ERROR_SUCCESS)
{
if (r == ERROR_NO_MORE_ITEMS)
break;
ereport(WARNING,
(errmsg_internal("could not enumerate registry subkeys to identify Windows timezone: %i", (int)r)));
break;
}
if ((r=RegOpenKeyEx(rootKey,keyname,0,KEY_READ,&key)) != ERROR_SUCCESS)
{
ereport(WARNING,
(errmsg_internal("could not open registry subkey to identify Windows timezone: %i", (int)r)));
break;
}
memset(zonename, 0, sizeof(zonename));
namesize = sizeof(zonename);
if ((r=RegQueryValueEx(key, "Std", NULL, NULL, zonename, &namesize)) != ERROR_SUCCESS)
{
ereport(WARNING,
(errmsg_internal("could not query value for 'std' to identify Windows timezone: %i", (int)r)));
RegCloseKey(key);
break;
}
if (strcmp(tzname, zonename) == 0)
{
/* Matched zone */
strcpy(localtzname, keyname);
RegCloseKey(key);
break;
}
memset(zonename, 0, sizeof(zonename));
namesize = sizeof(zonename);
if ((r=RegQueryValueEx(key, "Dlt", NULL, NULL, zonename, &namesize)) != ERROR_SUCCESS)
{
ereport(WARNING,
(errmsg_internal("could not query value for 'dlt' to identify Windows timezone: %i", (int)r)));
RegCloseKey(key);
break;
}
if (strcmp(tzname, zonename) == 0)
{
/* Matched DST zone */
strcpy(localtzname, keyname);
RegCloseKey(key);
break;
}
RegCloseKey(key);
}
RegCloseKey(rootKey);
if (localtzname[0])
{
/* Found a localized name, so scan for that one too */
for (i = 0; win32_tzmap[i].stdname != NULL; i++)
{
if (strcmp(localtzname, win32_tzmap[i].stdname) == 0 ||
strcmp(localtzname, win32_tzmap[i].dstname) == 0)
{
elog(DEBUG4, "TZ \"%s\" matches localized Windows timezone \"%s\" (\"%s\")",
win32_tzmap[i].pgtzname, tzname, localtzname);
return win32_tzmap[i].pgtzname;
}
}
}
ereport(WARNING,
(errmsg("could not find a match for Windows timezone \"%s\"",
tzname)));
return NULL;
}
#endif /* WIN32 */
/*
* We keep loaded timezones in a hashtable so we don't have to
* load and parse the TZ definition file every time it is selected.
*/
static HTAB *timezone_cache = NULL;
static bool
init_timezone_hashtable(void)
{
HASHCTL hash_ctl;
MemSet(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = TZ_STRLEN_MAX;
hash_ctl.entrysize = sizeof(pg_tz);
timezone_cache = hash_create("Timezones",
31,
&hash_ctl,
HASH_ELEM);
if (!timezone_cache)
return false;
return true;
}
/*
* Load a timezone from file or from cache.
* Does not verify that the timezone is acceptable!
*/
struct pg_tz *
pg_tzset(const char *name)
{
pg_tz *tzp;
pg_tz tz;
if (strlen(name) >= TZ_STRLEN_MAX)
return NULL; /* not going to fit */
if (!timezone_cache)
if (!init_timezone_hashtable())
return NULL;
tzp = (pg_tz *)hash_search(timezone_cache,
name,
HASH_FIND,
NULL);
if (tzp)
/* Timezone found in cache, nothing more to do */
return tzp;
if (tzload(name, &tz.state) != 0)
{
if (name[0] == ':' || tzparse(name, &tz.state, FALSE) != 0)
/* Unknown timezone. Fail our call instead of loading GMT! */
return NULL;
}
strcpy(tz.TZname, name);
/* Save timezone in the cache */
tzp = hash_search(timezone_cache,
name,
HASH_ENTER,
NULL);
if (!tzp)
return NULL;
strcpy(tzp->TZname, tz.TZname);
memcpy(&tzp->state, &tz.state, sizeof(tz.state));
return tzp;
}
/*
* Check whether timezone is acceptable.
*
* What we are doing here is checking for leap-second-aware timekeeping.
* We need to reject such TZ settings because they'll wreak havoc with our
* date/time arithmetic.
*
* NB: this must NOT ereport(ERROR). The caller must get control back so that
* it can restore the old value of TZ if we don't like the new one.
*/
bool
tz_acceptable(pg_tz *tz)
{
struct pg_tm *tt;
pg_time_t time2000;
/*
* To detect leap-second timekeeping, run pg_localtime for what should
* be GMT midnight, 2000-01-01. Insist that the tm_sec value be zero;
* any other result has to be due to leap seconds.
*/
time2000 = (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY;
tt = pg_localtime(&time2000, tz);
if (!tt || tt->tm_sec != 0)
return false;
return true;
}
/*
* Set the global timezone. Verify that it's acceptable first.
*/
static bool
set_global_timezone(const char *tzname)
{
pg_tz *tznew;
if (!tzname || !tzname[0])
return false;
tznew = pg_tzset(tzname);
if (!tznew)
return false;
if (!tz_acceptable(tznew))
return false;
global_timezone = tznew;
return true;
}
/*
* Identify a suitable default timezone setting based on the environment,
* and make it active.
*
* We first look to the TZ environment variable. If not found or not
* recognized by our own code, we see if we can identify the timezone
* from the behavior of the system timezone library. When all else fails,
* fall back to GMT.
*/
static const char *
select_default_timezone(void)
{
const char *def_tz;
def_tz = getenv("TZ");
if (set_global_timezone(def_tz))
return def_tz;
def_tz = identify_system_timezone();
if (set_global_timezone(def_tz))
return def_tz;
if (set_global_timezone("GMT"))
return "GMT";
ereport(FATAL,
(errmsg("could not select a suitable default timezone"),
errdetail("It appears that your GMT time zone uses leap seconds. PostgreSQL does not support leap seconds.")));
return NULL; /* keep compiler quiet */
}
/*
* Initialize timezone library
*
* This is called after initial loading of postgresql.conf. If no TimeZone
* setting was found therein, we try to derive one from the environment.
*/
void
pg_timezone_initialize(void)
{
/* Do we need to try to figure the timezone? */
if (pg_strcasecmp(GetConfigOption("timezone"), "UNKNOWN") == 0)
{
const char *def_tz;
/* Select setting */
def_tz = select_default_timezone();
/* Tell GUC about the value. Will redundantly call pg_tzset() */
SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ARGV);
}
}
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