/*------------------------------------------------------------------------- * * findtimezone.c * Functions for determining the default timezone to use. * * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group * * IDENTIFICATION * src/bin/initdb/findtimezone.c * *------------------------------------------------------------------------- */ #include "postgres_fe.h" #include #include #include #include #include "pgtz.h" /* Ideally this would be in a .h file, but it hardly seems worth the trouble */ extern const char *select_default_timezone(const char *share_path); #ifndef SYSTEMTZDIR static char tzdirpath[MAXPGPATH]; #endif /* * Return full pathname of timezone data directory * * In this file, tzdirpath is assumed to be set up by select_default_timezone. */ static const char * pg_TZDIR(void) { #ifndef SYSTEMTZDIR /* normal case: timezone stuff is under our share dir */ return tzdirpath; #else /* we're configured to use system's timezone database */ return SYSTEMTZDIR; #endif } /* * Given a timezone name, open() the timezone data file. Return the * file descriptor if successful, -1 if not. * * This is simpler than the backend function of the same name because * we assume that the input string has the correct case already, so there * is no need for case-folding. (This is obviously true if we got the file * name from the filesystem to start with. The only other place it can come * from is the environment variable TZ, and there seems no need to allow * case variation in that; other programs aren't likely to.) * * If "canonname" is not NULL, then on success the canonical spelling of the * given name is stored there (the buffer must be > TZ_STRLEN_MAX bytes!). * This is redundant but kept for compatibility with the backend code. */ int pg_open_tzfile(const char *name, char *canonname) { char fullname[MAXPGPATH]; if (canonname) strlcpy(canonname, name, TZ_STRLEN_MAX + 1); strlcpy(fullname, pg_TZDIR(), sizeof(fullname)); if (strlen(fullname) + 1 + strlen(name) >= MAXPGPATH) return -1; /* not gonna fit */ strcat(fullname, "/"); strcat(fullname, name); return open(fullname, O_RDONLY | PG_BINARY, 0); } /* * Load a timezone definition. * Does not verify that the timezone is acceptable! * * This corresponds to the backend's pg_tzset(), except that we only support * one loaded timezone at a time. */ static pg_tz * pg_load_tz(const char *name) { static pg_tz tz; if (strlen(name) > TZ_STRLEN_MAX) return NULL; /* not going to fit */ /* * "GMT" is always sent to tzparse(); see comments for pg_tzset(). */ if (strcmp(name, "GMT") == 0) { if (!tzparse(name, &tz.state, true)) { /* This really, really should not happen ... */ return NULL; } } else if (tzload(name, NULL, &tz.state, true) != 0) { if (name[0] == ':' || !tzparse(name, &tz.state, false)) { return NULL; /* unknown timezone */ } } strcpy(tz.TZname, name); return &tz; } /* * 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 IANA database assigns multiple * names to many zones). We break ties by first checking for "preferred" * names (such as "UTC"), and then arbitrarily by preferring shorter, then * alphabetically earlier zone names. (If we did not explicitly prefer * "UTC", we would get the alias name "UCT" instead due to alphabetic * ordering.) * * Many modern systems use the IANA database, so if we can determine the * system's idea of which zone it is using and its behavior matches our zone * of the same name, we can skip the rather-expensive search through all the * zones in our database. This short-circuit path also ensures that we spell * the zone name the same way the system setting does, even in the presence * of multiple aliases for the same zone. * * Win32's native knowledge about timezones appears to be too incomplete * and too different from the IANA 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 */ struct tztry { int n_test_times; time_t test_times[MAX_TEST_TIMES]; }; static bool check_system_link_file(const char *linkname, struct tztry *tt, char *bestzonename); 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; tm.tm_isdst = -1; 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; /* Load timezone definition */ tz = pg_load_tz(tzname); if (!tz) return -1; /* unrecognized zone name */ /* Reject if leap seconds involved */ if (!pg_tz_acceptable(tz)) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "Reject TZ \"%s\": uses leap seconds\n", tzname); #endif 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) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s, system had no data\n", 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"); #endif return i; } if (!compare_tm(systm, pgtm)) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s versus %04d-%02d-%02d %02d:%02d:%02d %s\n", 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"); #endif 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) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "TZ \"%s\" scores %d: at %ld \"%s\" versus \"%s\"\n", tzname, i, (long) pgtt, pgtm->tm_zone, cbuf); #endif return i; } } } #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "TZ \"%s\" gets max score %d\n", tzname, i); #endif return i; } /* * Test whether given zone name is a perfect match to localtime() behavior */ static bool perfect_timezone_match(const char *tzname, struct tztry *tt) { return (score_timezone(tzname, tt) == tt->n_test_times); } /* * Try to identify a timezone name (in our terminology) that best matches the * observed behavior of the system localtime() function. */ 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 thisyear; 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 the * current year; this serves to quickly eliminate the vast majority of the * TZ database entries. If those dates match, we probe every week for 100 * years backwards from the current July. (Weekly resolution is good * enough to identify DST transition rules, since everybody switches on * Sundays.) This is sufficient to cover most of the Unix time_t range, * and we don't want to look further than that since many systems won't * have sane TZ behavior further back anyway. 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 IANA * database, without insisting on exact match. (Note: we probe Thursdays, * not Sundays, to avoid triggering DST-transition bugs in localtime * itself.) */ tnow = time(NULL); tm = localtime(&tnow); if (!tm) return NULL; /* give up if localtime is broken... */ thisyear = tm->tm_year + 1900; t = build_time_t(thisyear, 1, 15); /* * Round back to GMT midnight Thursday. This depends on the knowledge * that the time_t origin is Thu Jan 01 1970. (With a different origin * we'd be probing some other day of the week, but it wouldn't matter * anyway unless localtime() had DST-transition bugs.) */ t -= (t % T_WEEK); tt.n_test_times = 0; tt.test_times[tt.n_test_times++] = t; t = build_time_t(thisyear, 7, 15); t -= (t % T_WEEK); tt.test_times[tt.n_test_times++] = t; while (tt.n_test_times < MAX_TEST_TIMES) { t -= T_WEEK; tt.test_times[tt.n_test_times++] = t; } /* * Try to avoid the brute-force search by seeing if we can recognize the * system's timezone setting directly. * * Currently we just check /etc/localtime; there are other conventions for * this, but that seems to be the only one used on enough platforms to be * worth troubling over. */ if (check_system_link_file("/etc/localtime", &tt, resultbuf)) return resultbuf; /* No luck, so search for the best-matching timezone file */ strlcpy(tmptzdir, pg_TZDIR(), sizeof(tmptzdir)); bestscore = -1; resultbuf[0] = '\0'; scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1, &tt, &bestscore, resultbuf); if (bestscore > 0) { /* Ignore IANA's rather silly "Factory" zone; use GMT instead */ if (strcmp(resultbuf, "Factory") == 0) return NULL; 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') { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not determine system time zone\n"); #endif return NULL; /* go to GMT */ } /* If we found DST then try STDDST */ 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 */ 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 * IANA 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); #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not recognize system time zone, using \"%s\"\n", resultbuf); #endif return resultbuf; } /* * Examine a system-provided symlink file to see if it tells us the timezone. * * Unfortunately, there is little standardization of how the system default * timezone is determined in the absence of a TZ environment setting. * But a common strategy is to create a symlink at a well-known place. * If "linkname" identifies a readable symlink, and the tail of its contents * matches a zone name we know, and the actual behavior of localtime() agrees * with what we think that zone means, then we may use that zone name. * * We insist on a perfect behavioral match, which might not happen if the * system has a different IANA database version than we do; but in that case * it seems best to fall back to the brute-force search. * * linkname is the symlink file location to probe. * * tt tells about the system timezone behavior we need to match. * * If we successfully identify a zone name, store it in *bestzonename and * return true; else return false. bestzonename must be a buffer of length * TZ_STRLEN_MAX + 1. */ static bool check_system_link_file(const char *linkname, struct tztry *tt, char *bestzonename) { #ifdef HAVE_READLINK char link_target[MAXPGPATH]; int len; const char *cur_name; /* * Try to read the symlink. If not there, not a symlink, etc etc, just * quietly fail; the precise reason needn't concern us. */ len = readlink(linkname, link_target, sizeof(link_target)); if (len < 0 || len >= sizeof(link_target)) return false; link_target[len] = '\0'; #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "symbolic link \"%s\" contains \"%s\"\n", linkname, link_target); #endif /* * The symlink is probably of the form "/path/to/zones/zone/name", or * possibly it is a relative path. Nobody puts their zone DB directly in * the root directory, so we can definitely skip the first component; but * after that it's trial-and-error to identify which path component begins * the zone name. */ cur_name = link_target; while (*cur_name) { /* Advance to next segment of path */ cur_name = strchr(cur_name + 1, '/'); if (cur_name == NULL) break; /* If there are consecutive slashes, skip all, as the kernel would */ do { cur_name++; } while (*cur_name == '/'); /* * Test remainder of path to see if it is a matching zone name. * Relative paths might contain ".."; we needn't bother testing if the * first component is that. Also defend against overlength names. */ if (*cur_name && *cur_name != '.' && strlen(cur_name) <= TZ_STRLEN_MAX && perfect_timezone_match(cur_name, tt)) { /* Success! */ strcpy(bestzonename, cur_name); return true; } } /* Couldn't extract a matching zone name */ return false; #else /* No symlinks? Forget it */ return false; #endif } /* * Given a timezone name, determine whether it should be preferred over other * names which are equally good matches. The output is arbitrary but we will * use 0 for "neutral" default preference; larger values are more preferred. */ static int zone_name_pref(const char *zonename) { /* * Prefer UTC over alternatives such as UCT. Also prefer Etc/UTC over * Etc/UCT; but UTC is preferred to Etc/UTC. */ if (strcmp(zonename, "UTC") == 0) return 50; if (strcmp(zonename, "Etc/UTC") == 0) return 40; /* * We don't want to pick "localtime" or "posixrules", unless we can find * no other name for the prevailing zone. Those aren't real zone names. */ if (strcmp(zonename, "localtime") == 0 || strcmp(zonename, "posixrules") == 0) return -50; return 0; } /* * 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); char **names; char **namep; names = pgfnames(tzdir); if (!names) return; for (namep = names; *namep; namep++) { char *name = *namep; struct stat statbuf; /* Ignore . and .., plus any other "hidden" files */ if (name[0] == '.') continue; snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len, "/%s", name); if (stat(tzdir, &statbuf) != 0) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not stat \"%s\": %s\n", tzdir, strerror(errno)); #endif tzdir[tzdir_orig_len] = '\0'; 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; strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1); } else if (score == *bestscore) { /* Consider how to break a tie */ int namepref = (zone_name_pref(tzdirsub) - zone_name_pref(bestzonename)); if (namepref > 0 || (namepref == 0 && (strlen(tzdirsub) < strlen(bestzonename) || (strlen(tzdirsub) == strlen(bestzonename) && strcmp(tzdirsub, bestzonename) < 0)))) strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1); } } /* Restore tzdir */ tzdir[tzdir_orig_len] = '\0'; } pgfnames_cleanup(names); } #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 7, Windows 10, and Windows Server 2019. Some recent * additions have been made by comparing to the CLDR project's * windowsZones.xml file. * * The zones have been matched to IANA timezones based on CLDR's mapping * for "territory 001". */ { /* (UTC+04:30) Kabul */ "Afghanistan Standard Time", "Afghanistan Daylight Time", "Asia/Kabul" }, { /* (UTC-09:00) Alaska */ "Alaskan Standard Time", "Alaskan Daylight Time", "America/Anchorage" }, { /* (UTC-10:00) Aleutian Islands */ "Aleutian Standard Time", "Aleutian Daylight Time", "America/Adak" }, { /* (UTC+07:00) Barnaul, Gorno-Altaysk */ "Altai Standard Time", "Altai Daylight Time", "Asia/Barnaul" }, { /* (UTC+03:00) Kuwait, Riyadh */ "Arab Standard Time", "Arab Daylight Time", "Asia/Riyadh" }, { /* (UTC+04:00) Abu Dhabi, Muscat */ "Arabian Standard Time", "Arabian Daylight Time", "Asia/Dubai" }, { /* (UTC+03:00) Baghdad */ "Arabic Standard Time", "Arabic Daylight Time", "Asia/Baghdad" }, { /* (UTC-03:00) City of Buenos Aires */ "Argentina Standard Time", "Argentina Daylight Time", "America/Buenos_Aires" }, { /* (UTC+04:00) Baku, Tbilisi, Yerevan */ "Armenian Standard Time", "Armenian Daylight Time", "Asia/Yerevan" }, { /* (UTC+04:00) Astrakhan, Ulyanovsk */ "Astrakhan Standard Time", "Astrakhan Daylight Time", "Europe/Astrakhan" }, { /* (UTC-04:00) Atlantic Time (Canada) */ "Atlantic Standard Time", "Atlantic Daylight Time", "America/Halifax" }, { /* (UTC+09:30) Darwin */ "AUS Central Standard Time", "AUS Central Daylight Time", "Australia/Darwin" }, { /* (UTC+08:45) Eucla */ "Aus Central W. Standard Time", "Aus Central W. Daylight Time", "Australia/Eucla" }, { /* (UTC+10:00) Canberra, Melbourne, Sydney */ "AUS Eastern Standard Time", "AUS Eastern Daylight Time", "Australia/Sydney" }, { /* (UTC+04:00) Baku */ "Azerbaijan Standard Time", "Azerbaijan Daylight Time", "Asia/Baku" }, { /* (UTC-01:00) Azores */ "Azores Standard Time", "Azores Daylight Time", "Atlantic/Azores" }, { /* (UTC-03:00) Salvador */ "Bahia Standard Time", "Bahia Daylight Time", "America/Bahia" }, { /* (UTC+06:00) Dhaka */ "Bangladesh Standard Time", "Bangladesh Daylight Time", "Asia/Dhaka" }, { /* (UTC+03:00) Minsk */ "Belarus Standard Time", "Belarus Daylight Time", "Europe/Minsk" }, { /* (UTC+11:00) Bougainville Island */ "Bougainville Standard Time", "Bougainville Daylight Time", "Pacific/Bougainville" }, { /* (UTC-01:00) Cabo Verde Is. */ "Cabo Verde Standard Time", "Cabo Verde Daylight Time", "Atlantic/Cape_Verde" }, { /* (UTC-06:00) Saskatchewan */ "Canada Central Standard Time", "Canada Central Daylight Time", "America/Regina" }, { /* (UTC-01:00) Cape Verde Is. */ "Cape Verde Standard Time", "Cape Verde Daylight Time", "Atlantic/Cape_Verde" }, { /* (UTC+04:00) Yerevan */ "Caucasus Standard Time", "Caucasus Daylight Time", "Asia/Yerevan" }, { /* (UTC+09:30) Adelaide */ "Cen. Australia Standard Time", "Cen. Australia Daylight Time", "Australia/Adelaide" }, { /* (UTC-06:00) Central America */ "Central America Standard Time", "Central America Daylight Time", "America/Guatemala" }, { /* (UTC+06:00) Astana */ "Central Asia Standard Time", "Central Asia Daylight Time", "Asia/Almaty" }, { /* (UTC-04:00) Cuiaba */ "Central Brazilian Standard Time", "Central Brazilian Daylight Time", "America/Cuiaba" }, { /* (UTC+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague */ "Central Europe Standard Time", "Central Europe Daylight Time", "Europe/Budapest" }, { /* (UTC+01:00) Sarajevo, Skopje, Warsaw, Zagreb */ "Central European Standard Time", "Central European Daylight Time", "Europe/Warsaw" }, { /* (UTC+11:00) Solomon Is., New Caledonia */ "Central Pacific Standard Time", "Central Pacific Daylight Time", "Pacific/Guadalcanal" }, { /* (UTC-06:00) Central Time (US & Canada) */ "Central Standard Time", "Central Daylight Time", "America/Chicago" }, { /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */ "Central Standard Time (Mexico)", "Central Daylight Time (Mexico)", "America/Mexico_City" }, { /* (UTC+12:45) Chatham Islands */ "Chatham Islands Standard Time", "Chatham Islands Daylight Time", "Pacific/Chatham" }, { /* (UTC+08:00) Beijing, Chongqing, Hong Kong, Urumqi */ "China Standard Time", "China Daylight Time", "Asia/Shanghai" }, { /* (UTC) Coordinated Universal Time */ "Coordinated Universal Time", "Coordinated Universal Time", "UTC" }, { /* (UTC-05:00) Havana */ "Cuba Standard Time", "Cuba Daylight Time", "America/Havana" }, { /* (UTC-12:00) International Date Line West */ "Dateline Standard Time", "Dateline Daylight Time", "Etc/GMT+12" }, { /* (UTC+03:00) Nairobi */ "E. Africa Standard Time", "E. Africa Daylight Time", "Africa/Nairobi" }, { /* (UTC+10:00) Brisbane */ "E. Australia Standard Time", "E. Australia Daylight Time", "Australia/Brisbane" }, { /* (UTC+02:00) Chisinau */ "E. Europe Standard Time", "E. Europe Daylight Time", "Europe/Chisinau" }, { /* (UTC-03:00) Brasilia */ "E. South America Standard Time", "E. South America Daylight Time", "America/Sao_Paulo" }, { /* (UTC-06:00) Easter Island */ "Easter Island Standard Time", "Easter Island Daylight Time", "Pacific/Easter" }, { /* (UTC-05:00) Eastern Time (US & Canada) */ "Eastern Standard Time", "Eastern Daylight Time", "America/New_York" }, { /* (UTC-05:00) Chetumal */ "Eastern Standard Time (Mexico)", "Eastern Daylight Time (Mexico)", "America/Cancun" }, { /* (UTC+02:00) Cairo */ "Egypt Standard Time", "Egypt Daylight Time", "Africa/Cairo" }, { /* (UTC+05:00) Ekaterinburg */ "Ekaterinburg Standard Time", "Ekaterinburg Daylight Time", "Asia/Yekaterinburg" }, { /* (UTC+12:00) Fiji */ "Fiji Standard Time", "Fiji Daylight Time", "Pacific/Fiji" }, { /* (UTC+02:00) Helsinki, Kyiv, Riga, Sofia, Tallinn, Vilnius */ "FLE Standard Time", "FLE Daylight Time", "Europe/Kiev" }, { /* (UTC+04:00) Tbilisi */ "Georgian Standard Time", "Georgian Daylight Time", "Asia/Tbilisi" }, { /* (UTC+00:00) Dublin, Edinburgh, Lisbon, London */ "GMT Standard Time", "GMT Daylight Time", "Europe/London" }, { /* (UTC-03:00) Greenland */ "Greenland Standard Time", "Greenland Daylight Time", "America/Godthab" }, { /* * Windows uses this zone name in various places that lie near the * prime meridian, but are not in the UK. However, most people * probably think that "Greenwich" means UK civil time, or maybe even * straight-up UTC. Atlantic/Reykjavik is a decent match for that * interpretation because Iceland hasn't observed DST since 1968. */ /* (UTC+00:00) Monrovia, Reykjavik */ "Greenwich Standard Time", "Greenwich Daylight Time", "Atlantic/Reykjavik" }, { /* (UTC+02:00) Athens, Bucharest */ "GTB Standard Time", "GTB Daylight Time", "Europe/Bucharest" }, { /* (UTC-05:00) Haiti */ "Haiti Standard Time", "Haiti Daylight Time", "America/Port-au-Prince" }, { /* (UTC-10:00) Hawaii */ "Hawaiian Standard Time", "Hawaiian Daylight Time", "Pacific/Honolulu" }, { /* (UTC+05:30) Chennai, Kolkata, Mumbai, New Delhi */ "India Standard Time", "India Daylight Time", "Asia/Calcutta" }, { /* (UTC+03:30) Tehran */ "Iran Standard Time", "Iran Daylight Time", "Asia/Tehran" }, { /* (UTC+02:00) Jerusalem */ "Israel Standard Time", "Israel Daylight Time", "Asia/Jerusalem" }, { /* (UTC+02:00) Jerusalem (old spelling of zone name) */ "Jerusalem Standard Time", "Jerusalem Daylight Time", "Asia/Jerusalem" }, { /* (UTC+02:00) Amman */ "Jordan Standard Time", "Jordan Daylight Time", "Asia/Amman" }, { /* (UTC+02:00) Kaliningrad */ "Kaliningrad Standard Time", "Kaliningrad Daylight Time", "Europe/Kaliningrad" }, { /* (UTC+12:00) Petropavlovsk-Kamchatsky - Old */ "Kamchatka Standard Time", "Kamchatka Daylight Time", "Asia/Kamchatka" }, { /* (UTC+09:00) Seoul */ "Korea Standard Time", "Korea Daylight Time", "Asia/Seoul" }, { /* (UTC+02:00) Tripoli */ "Libya Standard Time", "Libya Daylight Time", "Africa/Tripoli" }, { /* (UTC+14:00) Kiritimati Island */ "Line Islands Standard Time", "Line Islands Daylight Time", "Pacific/Kiritimati" }, { /* (UTC+10:30) Lord Howe Island */ "Lord Howe Standard Time", "Lord Howe Daylight Time", "Australia/Lord_Howe" }, { /* (UTC+11:00) Magadan */ "Magadan Standard Time", "Magadan Daylight Time", "Asia/Magadan" }, { /* (UTC-03:00) Punta Arenas */ "Magallanes Standard Time", "Magallanes Daylight Time", "America/Punta_Arenas" }, { /* (UTC+08:00) Kuala Lumpur, Singapore */ "Malay Peninsula Standard Time", "Malay Peninsula Daylight Time", "Asia/Kuala_Lumpur" }, { /* (UTC-09:30) Marquesas Islands */ "Marquesas Standard Time", "Marquesas Daylight Time", "Pacific/Marquesas" }, { /* (UTC+04:00) Port Louis */ "Mauritius Standard Time", "Mauritius Daylight Time", "Indian/Mauritius" }, { /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */ "Mexico Standard Time", "Mexico Daylight Time", "America/Mexico_City" }, { /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */ "Mexico Standard Time 2", "Mexico Daylight Time 2", "America/Chihuahua" }, { /* (UTC-02:00) Mid-Atlantic - Old */ "Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time", "Atlantic/South_Georgia" }, { /* (UTC+02:00) Beirut */ "Middle East Standard Time", "Middle East Daylight Time", "Asia/Beirut" }, { /* (UTC-03:00) Montevideo */ "Montevideo Standard Time", "Montevideo Daylight Time", "America/Montevideo" }, { /* (UTC+01:00) Casablanca */ "Morocco Standard Time", "Morocco Daylight Time", "Africa/Casablanca" }, { /* (UTC-07:00) Mountain Time (US & Canada) */ "Mountain Standard Time", "Mountain Daylight Time", "America/Denver" }, { /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */ "Mountain Standard Time (Mexico)", "Mountain Daylight Time (Mexico)", "America/Chihuahua" }, { /* (UTC+06:30) Yangon (Rangoon) */ "Myanmar Standard Time", "Myanmar Daylight Time", "Asia/Rangoon" }, { /* (UTC+07:00) Novosibirsk */ "N. Central Asia Standard Time", "N. Central Asia Daylight Time", "Asia/Novosibirsk" }, { /* (UTC+02:00) Windhoek */ "Namibia Standard Time", "Namibia Daylight Time", "Africa/Windhoek" }, { /* (UTC+05:45) Kathmandu */ "Nepal Standard Time", "Nepal Daylight Time", "Asia/Katmandu" }, { /* (UTC+12:00) Auckland, Wellington */ "New Zealand Standard Time", "New Zealand Daylight Time", "Pacific/Auckland" }, { /* (UTC-03:30) Newfoundland */ "Newfoundland Standard Time", "Newfoundland Daylight Time", "America/St_Johns" }, { /* (UTC+11:00) Norfolk Island */ "Norfolk Standard Time", "Norfolk Daylight Time", "Pacific/Norfolk" }, { /* (UTC+08:00) Irkutsk */ "North Asia East Standard Time", "North Asia East Daylight Time", "Asia/Irkutsk" }, { /* (UTC+07:00) Krasnoyarsk */ "North Asia Standard Time", "North Asia Daylight Time", "Asia/Krasnoyarsk" }, { /* (UTC+09:00) Pyongyang */ "North Korea Standard Time", "North Korea Daylight Time", "Asia/Pyongyang" }, { /* (UTC+07:00) Novosibirsk */ "Novosibirsk Standard Time", "Novosibirsk Daylight Time", "Asia/Novosibirsk" }, { /* (UTC+06:00) Omsk */ "Omsk Standard Time", "Omsk Daylight Time", "Asia/Omsk" }, { /* (UTC-04:00) Santiago */ "Pacific SA Standard Time", "Pacific SA Daylight Time", "America/Santiago" }, { /* (UTC-08:00) Pacific Time (US & Canada) */ "Pacific Standard Time", "Pacific Daylight Time", "America/Los_Angeles" }, { /* (UTC-08:00) Baja California */ "Pacific Standard Time (Mexico)", "Pacific Daylight Time (Mexico)", "America/Tijuana" }, { /* (UTC+05:00) Islamabad, Karachi */ "Pakistan Standard Time", "Pakistan Daylight Time", "Asia/Karachi" }, { /* (UTC-04:00) Asuncion */ "Paraguay Standard Time", "Paraguay Daylight Time", "America/Asuncion" }, { /* (UTC+05:00) Qyzylorda */ "Qyzylorda Standard Time", "Qyzylorda Daylight Time", "Asia/Qyzylorda" }, { /* (UTC+01:00) Brussels, Copenhagen, Madrid, Paris */ "Romance Standard Time", "Romance Daylight Time", "Europe/Paris" }, { /* (UTC+04:00) Izhevsk, Samara */ "Russia Time Zone 3", "Russia Time Zone 3", "Europe/Samara" }, { /* (UTC+11:00) Chokurdakh */ "Russia Time Zone 10", "Russia Time Zone 10", "Asia/Srednekolymsk" }, { /* (UTC+12:00) Anadyr, Petropavlovsk-Kamchatsky */ "Russia Time Zone 11", "Russia Time Zone 11", "Asia/Kamchatka" }, { /* (UTC+02:00) Kaliningrad */ "Russia TZ 1 Standard Time", "Russia TZ 1 Daylight Time", "Europe/Kaliningrad" }, { /* (UTC+03:00) Moscow, St. Petersburg */ "Russia TZ 2 Standard Time", "Russia TZ 2 Daylight Time", "Europe/Moscow" }, { /* (UTC+04:00) Izhevsk, Samara */ "Russia TZ 3 Standard Time", "Russia TZ 3 Daylight Time", "Europe/Samara" }, { /* (UTC+05:00) Ekaterinburg */ "Russia TZ 4 Standard Time", "Russia TZ 4 Daylight Time", "Asia/Yekaterinburg" }, { /* (UTC+06:00) Novosibirsk (RTZ 5) */ "Russia TZ 5 Standard Time", "Russia TZ 5 Daylight Time", "Asia/Novosibirsk" }, { /* (UTC+07:00) Krasnoyarsk */ "Russia TZ 6 Standard Time", "Russia TZ 6 Daylight Time", "Asia/Krasnoyarsk" }, { /* (UTC+08:00) Irkutsk */ "Russia TZ 7 Standard Time", "Russia TZ 7 Daylight Time", "Asia/Irkutsk" }, { /* (UTC+09:00) Yakutsk */ "Russia TZ 8 Standard Time", "Russia TZ 8 Daylight Time", "Asia/Yakutsk" }, { /* (UTC+10:00) Vladivostok */ "Russia TZ 9 Standard Time", "Russia TZ 9 Daylight Time", "Asia/Vladivostok" }, { /* (UTC+11:00) Chokurdakh */ "Russia TZ 10 Standard Time", "Russia TZ 10 Daylight Time", "Asia/Magadan" }, { /* (UTC+12:00) Anadyr, Petropavlovsk-Kamchatsky */ "Russia TZ 11 Standard Time", "Russia TZ 11 Daylight Time", "Asia/Anadyr" }, { /* (UTC+03:00) Moscow, St. Petersburg */ "Russian Standard Time", "Russian Daylight Time", "Europe/Moscow" }, { /* (UTC-03:00) Cayenne, Fortaleza */ "SA Eastern Standard Time", "SA Eastern Daylight Time", "America/Cayenne" }, { /* (UTC-05:00) Bogota, Lima, Quito, Rio Branco */ "SA Pacific Standard Time", "SA Pacific Daylight Time", "America/Bogota" }, { /* (UTC-04:00) Georgetown, La Paz, Manaus, San Juan */ "SA Western Standard Time", "SA Western Daylight Time", "America/La_Paz" }, { /* (UTC-03:00) Saint Pierre and Miquelon */ "Saint Pierre Standard Time", "Saint Pierre Daylight Time", "America/Miquelon" }, { /* (UTC+11:00) Sakhalin */ "Sakhalin Standard Time", "Sakhalin Daylight Time", "Asia/Sakhalin" }, { /* (UTC+13:00) Samoa */ "Samoa Standard Time", "Samoa Daylight Time", "Pacific/Apia" }, { /* (UTC+00:00) Sao Tome */ "Sao Tome Standard Time", "Sao Tome Daylight Time", "Africa/Sao_Tome" }, { /* (UTC+04:00) Saratov */ "Saratov Standard Time", "Saratov Daylight Time", "Europe/Saratov" }, { /* (UTC+07:00) Bangkok, Hanoi, Jakarta */ "SE Asia Standard Time", "SE Asia Daylight Time", "Asia/Bangkok" }, { /* (UTC+08:00) Kuala Lumpur, Singapore */ "Singapore Standard Time", "Singapore Daylight Time", "Asia/Singapore" }, { /* (UTC+02:00) Harare, Pretoria */ "South Africa Standard Time", "South Africa Daylight Time", "Africa/Johannesburg" }, { /* (UTC+02:00) Juba */ "South Sudan Standard Time", "South Sudan Daylight Time", "Africa/Juba" }, { /* (UTC+05:30) Sri Jayawardenepura */ "Sri Lanka Standard Time", "Sri Lanka Daylight Time", "Asia/Colombo" }, { /* (UTC+02:00) Khartoum */ "Sudan Standard Time", "Sudan Daylight Time", "Africa/Khartoum" }, { /* (UTC+02:00) Damascus */ "Syria Standard Time", "Syria Daylight Time", "Asia/Damascus" }, { /* (UTC+08:00) Taipei */ "Taipei Standard Time", "Taipei Daylight Time", "Asia/Taipei" }, { /* (UTC+10:00) Hobart */ "Tasmania Standard Time", "Tasmania Daylight Time", "Australia/Hobart" }, { /* (UTC-03:00) Araguaina */ "Tocantins Standard Time", "Tocantins Daylight Time", "America/Araguaina" }, { /* (UTC+09:00) Osaka, Sapporo, Tokyo */ "Tokyo Standard Time", "Tokyo Daylight Time", "Asia/Tokyo" }, { /* (UTC+07:00) Tomsk */ "Tomsk Standard Time", "Tomsk Daylight Time", "Asia/Tomsk" }, { /* (UTC+13:00) Nuku'alofa */ "Tonga Standard Time", "Tonga Daylight Time", "Pacific/Tongatapu" }, { /* (UTC+09:00) Chita */ "Transbaikal Standard Time", "Transbaikal Daylight Time", "Asia/Chita" }, { /* (UTC+03:00) Istanbul */ "Turkey Standard Time", "Turkey Daylight Time", "Europe/Istanbul" }, { /* (UTC-05:00) Turks and Caicos */ "Turks And Caicos Standard Time", "Turks And Caicos Daylight Time", "America/Grand_Turk" }, { /* (UTC+08:00) Ulaanbaatar */ "Ulaanbaatar Standard Time", "Ulaanbaatar Daylight Time", "Asia/Ulaanbaatar" }, { /* (UTC-05:00) Indiana (East) */ "US Eastern Standard Time", "US Eastern Daylight Time", "America/Indianapolis" }, { /* (UTC-07:00) Arizona */ "US Mountain Standard Time", "US Mountain Daylight Time", "America/Phoenix" }, { /* (UTC) Coordinated Universal Time */ "UTC", "UTC", "UTC" }, { /* (UTC+12:00) Coordinated Universal Time+12 */ "UTC+12", "UTC+12", "Etc/GMT-12" }, { /* (UTC+13:00) Coordinated Universal Time+13 */ "UTC+13", "UTC+13", "Etc/GMT-13" }, { /* (UTC-02:00) Coordinated Universal Time-02 */ "UTC-02", "UTC-02", "Etc/GMT+2" }, { /* (UTC-08:00) Coordinated Universal Time-08 */ "UTC-08", "UTC-08", "Etc/GMT+8" }, { /* (UTC-09:00) Coordinated Universal Time-09 */ "UTC-09", "UTC-09", "Etc/GMT+9" }, { /* (UTC-11:00) Coordinated Universal Time-11 */ "UTC-11", "UTC-11", "Etc/GMT+11" }, { /* (UTC-04:00) Caracas */ "Venezuela Standard Time", "Venezuela Daylight Time", "America/Caracas" }, { /* (UTC+10:00) Vladivostok */ "Vladivostok Standard Time", "Vladivostok Daylight Time", "Asia/Vladivostok" }, { /* (UTC+04:00) Volgograd */ "Volgograd Standard Time", "Volgograd Daylight Time", "Europe/Volgograd" }, { /* (UTC+08:00) Perth */ "W. Australia Standard Time", "W. Australia Daylight Time", "Australia/Perth" }, { /* (UTC+01:00) West Central Africa */ "W. Central Africa Standard Time", "W. Central Africa Daylight Time", "Africa/Lagos" }, { /* (UTC+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna */ "W. Europe Standard Time", "W. Europe Daylight Time", "Europe/Berlin" }, { /* (UTC+07:00) Hovd */ "W. Mongolia Standard Time", "W. Mongolia Daylight Time", "Asia/Hovd" }, { /* (UTC+05:00) Ashgabat, Tashkent */ "West Asia Standard Time", "West Asia Daylight Time", "Asia/Tashkent" }, { /* (UTC+02:00) Gaza, Hebron */ "West Bank Gaza Standard Time", "West Bank Gaza Daylight Time", "Asia/Gaza" }, { /* (UTC+02:00) Gaza, Hebron */ "West Bank Standard Time", "West Bank Daylight Time", "Asia/Hebron" }, { /* (UTC+10:00) Guam, Port Moresby */ "West Pacific Standard Time", "West Pacific Daylight Time", "Pacific/Port_Moresby" }, { /* (UTC+09:00) Yakutsk */ "Yakutsk Standard Time", "Yakutsk Daylight Time", "Asia/Yakutsk" }, { /* (UTC-07:00) Yukon */ "Yukon Standard Time", "Yukon Daylight Time", "America/Whitehorse" }, { 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) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not identify system time zone: localtime() failed\n"); #endif return NULL; /* go to GMT */ } 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) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "TZ \"%s\" matches system time zone \"%s\"\n", win32_tzmap[i].pgtzname, tzname); #endif 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) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not open registry key to identify system time zone: error code %lu\n", GetLastError()); #endif return NULL; /* go to GMT */ } 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; #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not enumerate registry subkeys to identify system time zone: %d\n", (int) r); #endif break; } if ((r = RegOpenKeyEx(rootKey, keyname, 0, KEY_READ, &key)) != ERROR_SUCCESS) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not open registry subkey to identify system time zone: %d\n", (int) r); #endif break; } memset(zonename, 0, sizeof(zonename)); namesize = sizeof(zonename); if ((r = RegQueryValueEx(key, "Std", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not query value for key \"std\" to identify system time zone \"%s\": %d\n", keyname, (int) r); #endif RegCloseKey(key); continue; /* Proceed to look at the next timezone */ } 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, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not query value for key \"dlt\" to identify system time zone \"%s\": %d\n", keyname, (int) r); #endif RegCloseKey(key); continue; /* Proceed to look at the next timezone */ } 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) { #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "TZ \"%s\" matches localized system time zone \"%s\" (\"%s\")\n", win32_tzmap[i].pgtzname, tzname, localtzname); #endif return win32_tzmap[i].pgtzname; } } } #ifdef DEBUG_IDENTIFY_TIMEZONE fprintf(stderr, "could not find a match for system time zone \"%s\"\n", tzname); #endif return NULL; /* go to GMT */ } #endif /* WIN32 */ /* * Return true if the given zone name is valid and is an "acceptable" zone. */ static bool validate_zone(const char *tzname) { pg_tz *tz; if (!tzname || !tzname[0]) return false; tz = pg_load_tz(tzname); if (!tz) return false; if (!pg_tz_acceptable(tz)) return false; return true; } /* * Identify a suitable default timezone setting based on the environment. * * The installation share_path must be passed in, as that is the default * location for the timezone database directory. * * 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, * return NULL, indicating that we should default to GMT. */ const char * select_default_timezone(const char *share_path) { const char *tzname; /* Initialize timezone directory path, if needed */ #ifndef SYSTEMTZDIR snprintf(tzdirpath, sizeof(tzdirpath), "%s/timezone", share_path); #endif /* Check TZ environment variable */ tzname = getenv("TZ"); if (validate_zone(tzname)) return tzname; /* Nope, so try to identify the system timezone */ tzname = identify_system_timezone(); if (validate_zone(tzname)) return tzname; return NULL; }