greenplumn findtimezone 源码
greenplumn findtimezone 代码
文件路径：/src/bin/initdb/findtimezone.c
/*-------------------------------------------------------------------------
*
* findtimezone.c
* Functions for determining the default timezone to use.
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/bin/initdb/findtimezone.c
*
*-------------------------------------------------------------------------
*/
#include "postgres_fe.h"
#include <fcntl.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#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;
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 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
* 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.
*
* Ideally we'd prefer the zone.tab/zone1970.tab names, since in general those
* are the ones offered to the user to select from. But for the moment, to
* minimize changes in behaviour, simply prefer UTC over alternative spellings
* such as UCT that otherwise cause confusion. The existing "shortest first"
* rule would prefer "UTC" over "Etc/UTC" so keep that the same way (while
* still preferring Etc/UTC over Etc/UCT).
*/
static int
zone_name_pref(const char *zonename)
{
if (strcmp(zonename, "UTC") == 0)
return 50;
if (strcmp(zonename, "Etc/UTC") == 0)
return 40;
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 10 and Windows 7.
*
* The zones have been matched to IANA 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"
}, /* (UTC+04:30) Kabul */
{
"Alaskan Standard Time", "Alaskan Daylight Time",
"US/Alaska"
}, /* (UTC-09:00) Alaska */
{
"Aleutian Standard Time", "Aleutian Daylight Time",
"US/Aleutan"
}, /* (UTC-10:00) Aleutian Islands */
{
"Altai Standard Time", "Altai Daylight Time",
"Asia/Barnaul"
}, /* (UTC+07:00) Barnaul, Gorno-Altaysk */
{
"Arab Standard Time", "Arab Daylight Time",
"Asia/Kuwait"
}, /* (UTC+03:00) Kuwait, Riyadh */
{
"Arabian Standard Time", "Arabian Daylight Time",
"Asia/Muscat"
}, /* (UTC+04:00) Abu Dhabi, Muscat */
{
"Arabic Standard Time", "Arabic Daylight Time",
"Asia/Baghdad"
}, /* (UTC+03:00) Baghdad */
{
"Argentina Standard Time", "Argentina Daylight Time",
"America/Buenos_Aires"
}, /* (UTC-03:00) City of Buenos Aires */
{
"Armenian Standard Time", "Armenian Daylight Time",
"Asia/Yerevan"
}, /* (UTC+04:00) Baku, Tbilisi, Yerevan */
{
"Astrakhan Standard Time", "Astrakhan Daylight Time",
"Europe/Astrakhan"
}, /* (UTC+04:00) Astrakhan, Ulyanovsk */
{
"Atlantic Standard Time", "Atlantic Daylight Time",
"Canada/Atlantic"
}, /* (UTC-04:00) Atlantic Time (Canada) */
{
"AUS Central Standard Time", "AUS Central Daylight Time",
"Australia/Darwin"
}, /* (UTC+09:30) Darwin */
{
"Aus Central W. Standard Time", "Aus Central W. Daylight Time",
"Australia/Eucla"
}, /* (UTC+08:45) Eucla */
{
"AUS Eastern Standard Time", "AUS Eastern Daylight Time",
"Australia/Canberra"
}, /* (UTC+10:00) Canberra, Melbourne, Sydney */
{
"Azerbaijan Standard Time", "Azerbaijan Daylight Time",
"Asia/Baku"
}, /* (UTC+04:00) Baku */
{
"Azores Standard Time", "Azores Daylight Time",
"Atlantic/Azores"
}, /* (UTC-01:00) Azores */
{
"Bahia Standard Time", "Bahia Daylight Time",
"America/Salvador"
}, /* (UTC-03:00) Salvador */
{
"Bangladesh Standard Time", "Bangladesh Daylight Time",
"Asia/Dhaka"
}, /* (UTC+06:00) Dhaka */
{
"Bougainville Standard Time", "Bougainville Daylight Time",
"Pacific/Bougainville"
}, /* (UTC+11:00) Bougainville Island */
{
"Belarus Standard Time", "Belarus Daylight Time",
"Europe/Minsk"
}, /* (UTC+03:00) Minsk */
{
"Cabo Verde Standard Time", "Cabo Verde Daylight Time",
"Atlantic/Cape_Verde"
}, /* (UTC-01:00) Cabo Verde Is. */
{
"Chatham Islands Standard Time", "Chatham Islands Daylight Time",
"Pacific/Chatham"
}, /* (UTC+12:45) Chatham Islands */
{
"Canada Central Standard Time", "Canada Central Daylight Time",
"Canada/Saskatchewan"
}, /* (UTC-06:00) Saskatchewan */
{
"Cape Verde Standard Time", "Cape Verde Daylight Time",
"Atlantic/Cape_Verde"
}, /* (UTC-01:00) Cape Verde Is. */
{
"Caucasus Standard Time", "Caucasus Daylight Time",
"Asia/Baku"
}, /* (UTC+04:00) Yerevan */
{
"Cen. Australia Standard Time", "Cen. Australia Daylight Time",
"Australia/Adelaide"
}, /* (UTC+09:30) Adelaide */
/* Central America (other than Mexico) generally does not observe DST */
{
"Central America Standard Time", "Central America Daylight Time",
"CST6"
}, /* (UTC-06:00) Central America */
{
"Central Asia Standard Time", "Central Asia Daylight Time",
"Asia/Dhaka"
}, /* (UTC+06:00) Astana */
{
"Central Brazilian Standard Time", "Central Brazilian Daylight Time",
"America/Cuiaba"
}, /* (UTC-04:00) Cuiaba */
{
"Central Europe Standard Time", "Central Europe Daylight Time",
"Europe/Belgrade"
}, /* (UTC+01:00) Belgrade, Bratislava, Budapest,
* Ljubljana, Prague */
{
"Central European Standard Time", "Central European Daylight Time",
"Europe/Sarajevo"
}, /* (UTC+01:00) Sarajevo, Skopje, Warsaw,
* Zagreb */
{
"Central Pacific Standard Time", "Central Pacific Daylight Time",
"Pacific/Noumea"
}, /* (UTC+11:00) Solomon Is., New Caledonia */
{
"Central Standard Time", "Central Daylight Time",
"US/Central"
}, /* (UTC-06:00) Central Time (US & Canada) */
{
"Central Standard Time (Mexico)", "Central Daylight Time (Mexico)",
"America/Mexico_City"
}, /* (UTC-06:00) Guadalajara, Mexico City,
* Monterrey */
{
"China Standard Time", "China Daylight Time",
"Asia/Hong_Kong"
}, /* (UTC+08:00) Beijing, Chongqing, Hong Kong,
* Urumqi */
{
"Cuba Standard Time", "Cuba Daylight Time",
"America/Havana"
}, /* (UTC-05:00) Havana */
{
"Dateline Standard Time", "Dateline Daylight Time",
"Etc/UTC+12"
}, /* (UTC-12:00) International Date Line West */
{
"E. Africa Standard Time", "E. Africa Daylight Time",
"Africa/Nairobi"
}, /* (UTC+03:00) Nairobi */
{
"E. Australia Standard Time", "E. Australia Daylight Time",
"Australia/Brisbane"
}, /* (UTC+10:00) Brisbane */
{
"E. Europe Standard Time", "E. Europe Daylight Time",
"Europe/Bucharest"
}, /* (UTC+02:00) E. Europe */
{
"E. South America Standard Time", "E. South America Daylight Time",
"America/Araguaina"
}, /* (UTC-03:00) Brasilia */
{
"Eastern Standard Time", "Eastern Daylight Time",
"US/Eastern"
}, /* (UTC-05:00) Eastern Time (US & Canada) */
{
"Eastern Standard Time (Mexico)", "Eastern Daylight Time (Mexico)",
"America/Mexico_City"
}, /* (UTC-05:00) Chetumal */
{
"Easter Island Standard Time", "Easter Island Daylight Time",
"Pacific/Easter"
}, /* (UTC-06:00) Easter Island */
{
"Egypt Standard Time", "Egypt Daylight Time",
"Africa/Cairo"
}, /* (UTC+02:00) Cairo */
{
"Ekaterinburg Standard Time (RTZ 4)", "Ekaterinburg Daylight Time",
"Asia/Yekaterinburg"
}, /* (UTC+05:00) Ekaterinburg */
{
"Fiji Standard Time", "Fiji Daylight Time",
"Pacific/Fiji"
}, /* (UTC+12:00) Fiji */
{
"FLE Standard Time", "FLE Daylight Time",
"Europe/Helsinki"
}, /* (UTC+02:00) Helsinki, Kyiv, Riga, Sofia,
* Tallinn, Vilnius */
{
"Georgian Standard Time", "Georgian Daylight Time",
"Asia/Tbilisi"
}, /* (UTC+04:00) Tbilisi */
{
"GMT Standard Time", "GMT Daylight Time",
"Europe/London"
}, /* (UTC) Dublin, Edinburgh, Lisbon, London */
{
"Greenland Standard Time", "Greenland Daylight Time",
"America/Godthab"
}, /* (UTC-03:00) Greenland */
{
"Greenwich Standard Time", "Greenwich Daylight Time",
"Africa/Casablanca"
}, /* (UTC) Monrovia, Reykjavik */
{
"GTB Standard Time", "GTB Daylight Time",
"Europe/Athens"
}, /* (UTC+02:00) Athens, Bucharest */
{
"Haiti Standard Time", "Haiti Daylight Time",
"US/Eastern"
}, /* (UTC-05:00) Haiti */
{
"Hawaiian Standard Time", "Hawaiian Daylight Time",
"US/Hawaii"
}, /* (UTC-10:00) Hawaii */
{
"India Standard Time", "India Daylight Time",
"Asia/Calcutta"
}, /* (UTC+05:30) Chennai, Kolkata, Mumbai, New
* Delhi */
{
"Iran Standard Time", "Iran Daylight Time",
"Asia/Tehran"
}, /* (UTC+03:30) Tehran */
{
"Jerusalem Standard Time", "Jerusalem Daylight Time",
"Asia/Jerusalem"
}, /* (UTC+02:00) Jerusalem */
{
"Jordan Standard Time", "Jordan Daylight Time",
"Asia/Amman"
}, /* (UTC+02:00) Amman */
{
"Kamchatka Standard Time", "Kamchatka Daylight Time",
"Asia/Kamchatka"
}, /* (UTC+12:00) Petropavlovsk-Kamchatsky - Old */
{
"Korea Standard Time", "Korea Daylight Time",
"Asia/Seoul"
}, /* (UTC+09:00) Seoul */
{
"Libya Standard Time", "Libya Daylight Time",
"Africa/Tripoli"
}, /* (UTC+02:00) Tripoli */
{
"Line Islands Standard Time", "Line Islands Daylight Time",
"Pacific/Kiritimati"
}, /* (UTC+14:00) Kiritimati Island */
{
"Lord Howe Standard Time", "Lord Howe Daylight Time",
"Australia/Lord_Howe"
}, /* (UTC+10:30) Lord Howe Island */
{
"Magadan Standard Time", "Magadan Daylight Time",
"Asia/Magadan"
}, /* (UTC+10:00) Magadan */
{
"Marquesas Standard Time", "Marquesas Daylight Time",
"Pacific/Marquesas"
}, /* (UTC-09:30) Marquesas Islands */
{
"Mauritius Standard Time", "Mauritius Daylight Time",
"Indian/Mauritius"
}, /* (UTC+04:00) Port Louis */
{
"Mexico Standard Time", "Mexico Daylight Time",
"America/Mexico_City"
}, /* (UTC-06:00) Guadalajara, Mexico City,
* Monterrey */
{
"Mexico Standard Time 2", "Mexico Daylight Time 2",
"America/Chihuahua"
}, /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
{
"Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
"Atlantic/South_Georgia"
}, /* (UTC-02:00) Mid-Atlantic - Old */
{
"Middle East Standard Time", "Middle East Daylight Time",
"Asia/Beirut"
}, /* (UTC+02:00) Beirut */
{
"Montevideo Standard Time", "Montevideo Daylight Time",
"America/Montevideo"
}, /* (UTC-03:00) Montevideo */
{
"Morocco Standard Time", "Morocco Daylight Time",
"Africa/Casablanca"
}, /* (UTC) Casablanca */
{
"Mountain Standard Time", "Mountain Daylight Time",
"US/Mountain"
}, /* (UTC-07:00) Mountain Time (US & Canada) */
{
"Mountain Standard Time (Mexico)", "Mountain Daylight Time (Mexico)",
"America/Chihuahua"
}, /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
{
"Myanmar Standard Time", "Myanmar Daylight Time",
"Asia/Rangoon"
}, /* (UTC+06:30) Yangon (Rangoon) */
{
"N. Central Asia Standard Time", "N. Central Asia Daylight Time",
"Asia/Novosibirsk"
}, /* (UTC+06:00) Novosibirsk (RTZ 5) */
{
"Namibia Standard Time", "Namibia Daylight Time",
"Africa/Windhoek"
}, /* (UTC+01:00) Windhoek */
{
"Nepal Standard Time", "Nepal Daylight Time",
"Asia/Katmandu"
}, /* (UTC+05:45) Kathmandu */
{
"New Zealand Standard Time", "New Zealand Daylight Time",
"Pacific/Auckland"
}, /* (UTC+12:00) Auckland, Wellington */
{
"Newfoundland Standard Time", "Newfoundland Daylight Time",
"Canada/Newfoundland"
}, /* (UTC-03:30) Newfoundland */
{
"Norfolk Standard Time", "Norfolk Daylight Time",
"Pacific/Norfolk"
}, /* (UTC+11:00) Norfolk Island */
{
"North Asia East Standard Time", "North Asia East Daylight Time",
"Asia/Irkutsk"
}, /* (UTC+08:00) Irkutsk, Ulaan Bataar */
{
"North Asia Standard Time", "North Asia Daylight Time",
"Asia/Krasnoyarsk"
}, /* (UTC+07:00) Krasnoyarsk */
{
"North Korea Standard Time", "North Korea Daylight Time",
"Asia/Pyongyang"
}, /* (UTC+08:30) Pyongyang */
{
"Pacific SA Standard Time", "Pacific SA Daylight Time",
"America/Santiago"
}, /* (UTC-03:00) Santiago */
{
"Pacific Standard Time", "Pacific Daylight Time",
"US/Pacific"
}, /* (UTC-08:00) Pacific Time (US & Canada) */
{
"Pacific Standard Time (Mexico)", "Pacific Daylight Time (Mexico)",
"America/Tijuana"
}, /* (UTC-08:00) Baja California */
{
"Pakistan Standard Time", "Pakistan Daylight Time",
"Asia/Karachi"
}, /* (UTC+05:00) Islamabad, Karachi */
{
"Paraguay Standard Time", "Paraguay Daylight Time",
"America/Asuncion"
}, /* (UTC-04:00) Asuncion */
{
"Romance Standard Time", "Romance Daylight Time",
"Europe/Brussels"
}, /* (UTC+01:00) Brussels, Copenhagen, Madrid,
* Paris */
{
"Russia TZ 1 Standard Time", "Russia TZ 1 Daylight Time",
"Europe/Kaliningrad"
}, /* (UTC+02:00) Kaliningrad (RTZ 1) */
{
"Russia TZ 2 Standard Time", "Russia TZ 2 Daylight Time",
"Europe/Moscow"
}, /* (UTC+03:00) Moscow, St. Petersburg,
* Volgograd (RTZ 2) */
{
"Russia TZ 3 Standard Time", "Russia TZ 3 Daylight Time",
"Europe/Samara"
}, /* (UTC+04:00) Izhevsk, Samara (RTZ 3) */
{
"Russia TZ 4 Standard Time", "Russia TZ 4 Daylight Time",
"Asia/Yekaterinburg"
}, /* (UTC+05:00) Ekaterinburg (RTZ 4) */
{
"Russia TZ 5 Standard Time", "Russia TZ 5 Daylight Time",
"Asia/Novosibirsk"
}, /* (UTC+06:00) Novosibirsk (RTZ 5) */
{
"Russia TZ 6 Standard Time", "Russia TZ 6 Daylight Time",
"Asia/Krasnoyarsk"
}, /* (UTC+07:00) Krasnoyarsk (RTZ 6) */
{
"Russia TZ 7 Standard Time", "Russia TZ 7 Daylight Time",
"Asia/Irkutsk"
}, /* (UTC+08:00) Irkutsk (RTZ 7) */
{
"Russia TZ 8 Standard Time", "Russia TZ 8 Daylight Time",
"Asia/Yakutsk"
}, /* (UTC+09:00) Yakutsk (RTZ 8) */
{
"Russia TZ 9 Standard Time", "Russia TZ 9 Daylight Time",
"Asia/Vladivostok"
}, /* (UTC+10:00) Vladivostok, Magadan (RTZ 9) */
{
"Russia TZ 10 Standard Time", "Russia TZ 10 Daylight Time",
"Asia/Magadan"
}, /* (UTC+11:00) Chokurdakh (RTZ 10) */
{
"Russia TZ 11 Standard Time", "Russia TZ 11 Daylight Time",
"Asia/Anadyr"
}, /* (UTC+12:00) Anadyr,
* Petropavlovsk-Kamchatsky (RTZ 11) */
{
"Russian Standard Time", "Russian Daylight Time",
"Europe/Moscow"
}, /* (UTC+03:00) Moscow, St. Petersburg,
* Volgograd */
{
"SA Eastern Standard Time", "SA Eastern Daylight Time",
"America/Buenos_Aires"
}, /* (UTC-03:00) Cayenne, Fortaleza */
{
"SA Pacific Standard Time", "SA Pacific Daylight Time",
"America/Bogota"
}, /* (UTC-05:00) Bogota, Lima, Quito, Rio Branco */
{
"SA Western Standard Time", "SA Western Daylight Time",
"America/Caracas"
}, /* (UTC-04:00) Georgetown, La Paz, Manaus, San
* Juan */
{
"Saint Pierre Standard Time", "Saint Pierre Daylight Time",
"America/Miquelon"
}, /* (UTC-03:00) Saint Pierre and Miquelon */
{
"Samoa Standard Time", "Samoa Daylight Time",
"Pacific/Samoa"
}, /* (UTC+13:00) Samoa */
{
"SE Asia Standard Time", "SE Asia Daylight Time",
"Asia/Bangkok"
}, /* (UTC+07:00) Bangkok, Hanoi, Jakarta */
{
"Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
"Asia/Kuala_Lumpur"
}, /* (UTC+08:00) Kuala Lumpur, Singapore */
{
"Sakhalin Standard Time", "Sakhalin Daylight Time",
"Asia/Sakhalin"
}, /* (UTC+11:00) Sakhalin */
{
"South Africa Standard Time", "South Africa Daylight Time",
"Africa/Harare"
}, /* (UTC+02:00) Harare, Pretoria */
{
"Sri Lanka Standard Time", "Sri Lanka Daylight Time",
"Asia/Colombo"
}, /* (UTC+05:30) Sri Jayawardenepura */
{
"Syria Standard Time", "Syria Daylight Time",
"Asia/Damascus"
}, /* (UTC+02:00) Damascus */
{
"Taipei Standard Time", "Taipei Daylight Time",
"Asia/Taipei"
}, /* (UTC+08:00) Taipei */
{
"Tasmania Standard Time", "Tasmania Daylight Time",
"Australia/Hobart"
}, /* (UTC+10:00) Hobart */
{
"Tocantins Standard Time", "Tocantins Daylight Time",
"America/Araguaina"
}, /* (UTC-03:00) Araguaina */
{
"Tokyo Standard Time", "Tokyo Daylight Time",
"Asia/Tokyo"
}, /* (UTC+09:00) Osaka, Sapporo, Tokyo */
{
"Tonga Standard Time", "Tonga Daylight Time",
"Pacific/Tongatapu"
}, /* (UTC+13:00) Nuku'alofa */
{
"Tomsk Standard Time", "Tomsk Daylight Time",
"Asia/Tomsk"
}, /* (UTC+07:00) Tomsk */
{
"Transbaikal Standard Time", "Transbaikal Daylight Time",
"Asia/Chita"
}, /* (UTC+09:00) Chita */
{
"Turkey Standard Time", "Turkey Daylight Time",
"Europe/Istanbul"
}, /* (UTC+02:00) Istanbul */
{
"Turks and Caicos Standard Time", "Turks and Caicos Daylight Time",
"America/Grand_Turk"
}, /* (UTC-04:00) Turks and Caicos */
{
"Ulaanbaatar Standard Time", "Ulaanbaatar Daylight Time",
"Asia/Ulaanbaatar",
}, /* (UTC+08:00) Ulaanbaatar */
{
"US Eastern Standard Time", "US Eastern Daylight Time",
"US/Eastern"
}, /* (UTC-05:00) Indiana (East) */
{
"US Mountain Standard Time", "US Mountain Daylight Time",
"US/Arizona"
}, /* (UTC-07:00) Arizona */
{
"Coordinated Universal Time", "Coordinated Universal Time",
"UTC"
}, /* (UTC) Coordinated Universal Time */
{
"UTC+12", "UTC+12",
"Etc/GMT+12"
}, /* (UTC+12:00) Coordinated Universal Time+12 */
{
"UTC-02", "UTC-02",
"Etc/GMT-02"
}, /* (UTC-02:00) Coordinated Universal Time-02 */
{
"UTC-08", "UTC-08",
"Etc/GMT-08"
}, /* (UTC-08:00) Coordinated Universal Time-08 */
{
"UTC-09", "UTC-09",
"Etc/GMT-09"
}, /* (UTC-09:00) Coordinated Universal Time-09 */
{
"UTC-11", "UTC-11",
"Etc/GMT-11"
}, /* (UTC-11:00) Coordinated Universal Time-11 */
{
"Venezuela Standard Time", "Venezuela Daylight Time",
"America/Caracas",
}, /* (UTC-04:30) Caracas */
{
"Vladivostok Standard Time", "Vladivostok Daylight Time",
"Asia/Vladivostok"
}, /* (UTC+10:00) Vladivostok (RTZ 9) */
{
"W. Australia Standard Time", "W. Australia Daylight Time",
"Australia/Perth"
}, /* (UTC+08:00) Perth */
#ifdef NOT_USED
/* Could not find a match for this one (just a guess). Excluded for now. */
{
"W. Central Africa Standard Time", "W. Central Africa Daylight Time",
"WAT"
}, /* (UTC+01:00) West Central Africa */
#endif
{
"W. Europe Standard Time", "W. Europe Daylight Time",
"CET"
}, /* (UTC+01:00) Amsterdam, Berlin, Bern, Rome,
* Stockholm, Vienna */
{
"W. Mongolia Standard Time", "W. Mongolia Daylight Time",
"Asia/Hovd"
}, /* (UTC+07:00) Hovd */
{
"West Asia Standard Time", "West Asia Daylight Time",
"Asia/Karachi"
}, /* (UTC+05:00) Ashgabat, Tashkent */
{
"West Bank Gaza Standard Time", "West Bank Gaza Daylight Time",
"Asia/Gaza"
}, /* (UTC+02:00) Gaza, Hebron */
{
"West Pacific Standard Time", "West Pacific Daylight Time",
"Pacific/Guam"
}, /* (UTC+10:00) Guam, Port Moresby */
{
"Yakutsk Standard Time", "Yakutsk Daylight Time",
"Asia/Yakutsk"
}, /* (UTC+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)
{
#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;
}
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