LCOV - code coverage report
Current view: top level - src/bin/initdb - findtimezone.c (source / functions) Hit Total Coverage
Test: PostgreSQL 15devel Lines: 102 210 48.6 %
Date: 2021-12-05 01:09:12 Functions: 11 14 78.6 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * findtimezone.c
       4             :  *    Functions for determining the default timezone to use.
       5             :  *
       6             :  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
       7             :  *
       8             :  * IDENTIFICATION
       9             :  *    src/bin/initdb/findtimezone.c
      10             :  *
      11             :  *-------------------------------------------------------------------------
      12             :  */
      13             : #include "postgres_fe.h"
      14             : 
      15             : #include <fcntl.h>
      16             : #include <sys/stat.h>
      17             : #include <time.h>
      18             : #include <unistd.h>
      19             : 
      20             : #include "pgtz.h"
      21             : 
      22             : /* Ideally this would be in a .h file, but it hardly seems worth the trouble */
      23             : extern const char *select_default_timezone(const char *share_path);
      24             : 
      25             : 
      26             : #ifndef SYSTEMTZDIR
      27             : static char tzdirpath[MAXPGPATH];
      28             : #endif
      29             : 
      30             : 
      31             : /*
      32             :  * Return full pathname of timezone data directory
      33             :  *
      34             :  * In this file, tzdirpath is assumed to be set up by select_default_timezone.
      35             :  */
      36             : static const char *
      37        1928 : pg_TZDIR(void)
      38             : {
      39             : #ifndef SYSTEMTZDIR
      40             :     /* normal case: timezone stuff is under our share dir */
      41        1928 :     return tzdirpath;
      42             : #else
      43             :     /* we're configured to use system's timezone database */
      44             :     return SYSTEMTZDIR;
      45             : #endif
      46             : }
      47             : 
      48             : 
      49             : /*
      50             :  * Given a timezone name, open() the timezone data file.  Return the
      51             :  * file descriptor if successful, -1 if not.
      52             :  *
      53             :  * This is simpler than the backend function of the same name because
      54             :  * we assume that the input string has the correct case already, so there
      55             :  * is no need for case-folding.  (This is obviously true if we got the file
      56             :  * name from the filesystem to start with.  The only other place it can come
      57             :  * from is the environment variable TZ, and there seems no need to allow
      58             :  * case variation in that; other programs aren't likely to.)
      59             :  *
      60             :  * If "canonname" is not NULL, then on success the canonical spelling of the
      61             :  * given name is stored there (the buffer must be > TZ_STRLEN_MAX bytes!).
      62             :  * This is redundant but kept for compatibility with the backend code.
      63             :  */
      64             : int
      65        1928 : pg_open_tzfile(const char *name, char *canonname)
      66             : {
      67             :     char        fullname[MAXPGPATH];
      68             : 
      69        1928 :     if (canonname)
      70           0 :         strlcpy(canonname, name, TZ_STRLEN_MAX + 1);
      71             : 
      72        1928 :     strlcpy(fullname, pg_TZDIR(), sizeof(fullname));
      73        1928 :     if (strlen(fullname) + 1 + strlen(name) >= MAXPGPATH)
      74           0 :         return -1;              /* not gonna fit */
      75        1928 :     strcat(fullname, "/");
      76        1928 :     strcat(fullname, name);
      77             : 
      78        1928 :     return open(fullname, O_RDONLY | PG_BINARY, 0);
      79             : }
      80             : 
      81             : 
      82             : 
      83             : /*
      84             :  * Load a timezone definition.
      85             :  * Does not verify that the timezone is acceptable!
      86             :  *
      87             :  * This corresponds to the backend's pg_tzset(), except that we only support
      88             :  * one loaded timezone at a time.
      89             :  */
      90             : static pg_tz *
      91        1928 : pg_load_tz(const char *name)
      92             : {
      93             :     static pg_tz tz;
      94             : 
      95        1928 :     if (strlen(name) > TZ_STRLEN_MAX)
      96           0 :         return NULL;            /* not going to fit */
      97             : 
      98             :     /*
      99             :      * "GMT" is always sent to tzparse(); see comments for pg_tzset().
     100             :      */
     101        1928 :     if (strcmp(name, "GMT") == 0)
     102             :     {
     103           0 :         if (!tzparse(name, &tz.state, true))
     104             :         {
     105             :             /* This really, really should not happen ... */
     106           0 :             return NULL;
     107             :         }
     108             :     }
     109        1928 :     else if (tzload(name, NULL, &tz.state, true) != 0)
     110             :     {
     111         964 :         if (name[0] == ':' || !tzparse(name, &tz.state, false))
     112             :         {
     113         964 :             return NULL;        /* unknown timezone */
     114             :         }
     115             :     }
     116             : 
     117         964 :     strcpy(tz.TZname, name);
     118             : 
     119         964 :     return &tz;
     120             : }
     121             : 
     122             : 
     123             : /*
     124             :  * The following block of code attempts to determine which timezone in our
     125             :  * timezone database is the best match for the active system timezone.
     126             :  *
     127             :  * On most systems, we rely on trying to match the observable behavior of
     128             :  * the C library's localtime() function.  The database zone that matches
     129             :  * furthest into the past is the one to use.  Often there will be several
     130             :  * zones with identical rankings (since the IANA database assigns multiple
     131             :  * names to many zones).  We break ties by first checking for "preferred"
     132             :  * names (such as "UTC"), and then arbitrarily by preferring shorter, then
     133             :  * alphabetically earlier zone names.  (If we did not explicitly prefer
     134             :  * "UTC", we would get the alias name "UCT" instead due to alphabetic
     135             :  * ordering.)
     136             :  *
     137             :  * Many modern systems use the IANA database, so if we can determine the
     138             :  * system's idea of which zone it is using and its behavior matches our zone
     139             :  * of the same name, we can skip the rather-expensive search through all the
     140             :  * zones in our database.  This short-circuit path also ensures that we spell
     141             :  * the zone name the same way the system setting does, even in the presence
     142             :  * of multiple aliases for the same zone.
     143             :  *
     144             :  * Win32's native knowledge about timezones appears to be too incomplete
     145             :  * and too different from the IANA database for the above matching strategy
     146             :  * to be of any use. But there is just a limited number of timezones
     147             :  * available, so we can rely on a handmade mapping table instead.
     148             :  */
     149             : 
     150             : #ifndef WIN32
     151             : 
     152             : #define T_DAY   ((time_t) (60*60*24))
     153             : #define T_WEEK  ((time_t) (60*60*24*7))
     154             : #define T_MONTH ((time_t) (60*60*24*31))
     155             : 
     156             : #define MAX_TEST_TIMES (52*100) /* 100 years */
     157             : 
     158             : struct tztry
     159             : {
     160             :     int         n_test_times;
     161             :     time_t      test_times[MAX_TEST_TIMES];
     162             : };
     163             : 
     164             : static bool check_system_link_file(const char *linkname, struct tztry *tt,
     165             :                                    char *bestzonename);
     166             : static void scan_available_timezones(char *tzdir, char *tzdirsub,
     167             :                                      struct tztry *tt,
     168             :                                      int *bestscore, char *bestzonename);
     169             : 
     170             : 
     171             : /*
     172             :  * Get GMT offset from a system struct tm
     173             :  */
     174             : static int
     175           0 : get_timezone_offset(struct tm *tm)
     176             : {
     177             : #if defined(HAVE_STRUCT_TM_TM_ZONE)
     178           0 :     return tm->tm_gmtoff;
     179             : #elif defined(HAVE_INT_TIMEZONE)
     180             :     return -TIMEZONE_GLOBAL;
     181             : #else
     182             : #error No way to determine TZ? Can this happen?
     183             : #endif
     184             : }
     185             : 
     186             : /*
     187             :  * Convenience subroutine to convert y/m/d to time_t (NOT pg_time_t)
     188             :  */
     189             : static time_t
     190         964 : build_time_t(int year, int month, int day)
     191             : {
     192             :     struct tm   tm;
     193             : 
     194         964 :     memset(&tm, 0, sizeof(tm));
     195         964 :     tm.tm_mday = day;
     196         964 :     tm.tm_mon = month - 1;
     197         964 :     tm.tm_year = year - 1900;
     198         964 :     tm.tm_isdst = -1;
     199             : 
     200         964 :     return mktime(&tm);
     201             : }
     202             : 
     203             : /*
     204             :  * Does a system tm value match one we computed ourselves?
     205             :  */
     206             : static bool
     207     2506400 : compare_tm(struct tm *s, struct pg_tm *p)
     208             : {
     209     2506400 :     if (s->tm_sec != p->tm_sec ||
     210     2506400 :         s->tm_min != p->tm_min ||
     211     2506400 :         s->tm_hour != p->tm_hour ||
     212     2506400 :         s->tm_mday != p->tm_mday ||
     213     2506400 :         s->tm_mon != p->tm_mon ||
     214     2506400 :         s->tm_year != p->tm_year ||
     215     2506400 :         s->tm_wday != p->tm_wday ||
     216     2506400 :         s->tm_yday != p->tm_yday ||
     217     2506400 :         s->tm_isdst != p->tm_isdst)
     218           0 :         return false;
     219     2506400 :     return true;
     220             : }
     221             : 
     222             : /*
     223             :  * See how well a specific timezone setting matches the system behavior
     224             :  *
     225             :  * We score a timezone setting according to the number of test times it
     226             :  * matches.  (The test times are ordered later-to-earlier, but this routine
     227             :  * doesn't actually know that; it just scans until the first non-match.)
     228             :  *
     229             :  * We return -1 for a completely unusable setting; this is worse than the
     230             :  * score of zero for a setting that works but matches not even the first
     231             :  * test time.
     232             :  */
     233             : static int
     234        1446 : score_timezone(const char *tzname, struct tztry *tt)
     235             : {
     236             :     int         i;
     237             :     pg_time_t   pgtt;
     238             :     struct tm  *systm;
     239             :     struct pg_tm *pgtm;
     240             :     char        cbuf[TZ_STRLEN_MAX + 1];
     241             :     pg_tz      *tz;
     242             : 
     243             :     /* Load timezone definition */
     244        1446 :     tz = pg_load_tz(tzname);
     245        1446 :     if (!tz)
     246         964 :         return -1;              /* unrecognized zone name */
     247             : 
     248             :     /* Reject if leap seconds involved */
     249         482 :     if (!pg_tz_acceptable(tz))
     250             :     {
     251             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     252             :         fprintf(stderr, "Reject TZ \"%s\": uses leap seconds\n", tzname);
     253             : #endif
     254           0 :         return -1;
     255             :     }
     256             : 
     257             :     /* Check for match at all the test times */
     258     2506882 :     for (i = 0; i < tt->n_test_times; i++)
     259             :     {
     260     2506400 :         pgtt = (pg_time_t) (tt->test_times[i]);
     261     2506400 :         pgtm = pg_localtime(&pgtt, tz);
     262     2506400 :         if (!pgtm)
     263           0 :             return -1;          /* probably shouldn't happen */
     264     2506400 :         systm = localtime(&(tt->test_times[i]));
     265     2506400 :         if (!systm)
     266             :         {
     267             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     268             :             fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s, system had no data\n",
     269             :                     tzname, i, (long) pgtt,
     270             :                     pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
     271             :                     pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
     272             :                     pgtm->tm_isdst ? "dst" : "std");
     273             : #endif
     274           0 :             return i;
     275             :         }
     276     2506400 :         if (!compare_tm(systm, pgtm))
     277             :         {
     278             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     279             :             fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s versus %04d-%02d-%02d %02d:%02d:%02d %s\n",
     280             :                     tzname, i, (long) pgtt,
     281             :                     pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
     282             :                     pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
     283             :                     pgtm->tm_isdst ? "dst" : "std",
     284             :                     systm->tm_year + 1900, systm->tm_mon + 1, systm->tm_mday,
     285             :                     systm->tm_hour, systm->tm_min, systm->tm_sec,
     286             :                     systm->tm_isdst ? "dst" : "std");
     287             : #endif
     288           0 :             return i;
     289             :         }
     290     2506400 :         if (systm->tm_isdst >= 0)
     291             :         {
     292             :             /* Check match of zone names, too */
     293     2506400 :             if (pgtm->tm_zone == NULL)
     294           0 :                 return -1;      /* probably shouldn't happen */
     295     2506400 :             memset(cbuf, 0, sizeof(cbuf));
     296     2506400 :             strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm);    /* zone abbr */
     297     2506400 :             if (strcmp(cbuf, pgtm->tm_zone) != 0)
     298             :             {
     299             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     300             :                 fprintf(stderr, "TZ \"%s\" scores %d: at %ld \"%s\" versus \"%s\"\n",
     301             :                         tzname, i, (long) pgtt,
     302             :                         pgtm->tm_zone, cbuf);
     303             : #endif
     304           0 :                 return i;
     305             :             }
     306             :         }
     307             :     }
     308             : 
     309             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     310             :     fprintf(stderr, "TZ \"%s\" gets max score %d\n", tzname, i);
     311             : #endif
     312             : 
     313         482 :     return i;
     314             : }
     315             : 
     316             : /*
     317             :  * Test whether given zone name is a perfect match to localtime() behavior
     318             :  */
     319             : static bool
     320        1446 : perfect_timezone_match(const char *tzname, struct tztry *tt)
     321             : {
     322        1446 :     return (score_timezone(tzname, tt) == tt->n_test_times);
     323             : }
     324             : 
     325             : 
     326             : /*
     327             :  * Try to identify a timezone name (in our terminology) that best matches the
     328             :  * observed behavior of the system localtime() function.
     329             :  */
     330             : static const char *
     331         482 : identify_system_timezone(void)
     332             : {
     333             :     static char resultbuf[TZ_STRLEN_MAX + 1];
     334             :     time_t      tnow;
     335             :     time_t      t;
     336             :     struct tztry tt;
     337             :     struct tm  *tm;
     338             :     int         thisyear;
     339             :     int         bestscore;
     340             :     char        tmptzdir[MAXPGPATH];
     341             :     int         std_ofs;
     342             :     char        std_zone_name[TZ_STRLEN_MAX + 1],
     343             :                 dst_zone_name[TZ_STRLEN_MAX + 1];
     344             :     char        cbuf[TZ_STRLEN_MAX + 1];
     345             : 
     346             :     /* Initialize OS timezone library */
     347         482 :     tzset();
     348             : 
     349             :     /*
     350             :      * Set up the list of dates to be probed to see how well our timezone
     351             :      * matches the system zone.  We first probe January and July of the
     352             :      * current year; this serves to quickly eliminate the vast majority of the
     353             :      * TZ database entries.  If those dates match, we probe every week for 100
     354             :      * years backwards from the current July.  (Weekly resolution is good
     355             :      * enough to identify DST transition rules, since everybody switches on
     356             :      * Sundays.)  This is sufficient to cover most of the Unix time_t range,
     357             :      * and we don't want to look further than that since many systems won't
     358             :      * have sane TZ behavior further back anyway.  The further back the zone
     359             :      * matches, the better we score it.  This may seem like a rather random
     360             :      * way of doing things, but experience has shown that system-supplied
     361             :      * timezone definitions are likely to have DST behavior that is right for
     362             :      * the recent past and not so accurate further back. Scoring in this way
     363             :      * allows us to recognize zones that have some commonality with the IANA
     364             :      * database, without insisting on exact match. (Note: we probe Thursdays,
     365             :      * not Sundays, to avoid triggering DST-transition bugs in localtime
     366             :      * itself.)
     367             :      */
     368         482 :     tnow = time(NULL);
     369         482 :     tm = localtime(&tnow);
     370         482 :     if (!tm)
     371           0 :         return NULL;            /* give up if localtime is broken... */
     372         482 :     thisyear = tm->tm_year + 1900;
     373             : 
     374         482 :     t = build_time_t(thisyear, 1, 15);
     375             : 
     376             :     /*
     377             :      * Round back to GMT midnight Thursday.  This depends on the knowledge
     378             :      * that the time_t origin is Thu Jan 01 1970.  (With a different origin
     379             :      * we'd be probing some other day of the week, but it wouldn't matter
     380             :      * anyway unless localtime() had DST-transition bugs.)
     381             :      */
     382         482 :     t -= (t % T_WEEK);
     383             : 
     384         482 :     tt.n_test_times = 0;
     385         482 :     tt.test_times[tt.n_test_times++] = t;
     386             : 
     387         482 :     t = build_time_t(thisyear, 7, 15);
     388         482 :     t -= (t % T_WEEK);
     389             : 
     390         482 :     tt.test_times[tt.n_test_times++] = t;
     391             : 
     392     2505918 :     while (tt.n_test_times < MAX_TEST_TIMES)
     393             :     {
     394     2505436 :         t -= T_WEEK;
     395     2505436 :         tt.test_times[tt.n_test_times++] = t;
     396             :     }
     397             : 
     398             :     /*
     399             :      * Try to avoid the brute-force search by seeing if we can recognize the
     400             :      * system's timezone setting directly.
     401             :      *
     402             :      * Currently we just check /etc/localtime; there are other conventions for
     403             :      * this, but that seems to be the only one used on enough platforms to be
     404             :      * worth troubling over.
     405             :      */
     406         482 :     if (check_system_link_file("/etc/localtime", &tt, resultbuf))
     407         482 :         return resultbuf;
     408             : 
     409             :     /* No luck, so search for the best-matching timezone file */
     410           0 :     strlcpy(tmptzdir, pg_TZDIR(), sizeof(tmptzdir));
     411           0 :     bestscore = -1;
     412           0 :     resultbuf[0] = '\0';
     413           0 :     scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1,
     414             :                              &tt,
     415             :                              &bestscore, resultbuf);
     416           0 :     if (bestscore > 0)
     417             :     {
     418             :         /* Ignore IANA's rather silly "Factory" zone; use GMT instead */
     419           0 :         if (strcmp(resultbuf, "Factory") == 0)
     420           0 :             return NULL;
     421           0 :         return resultbuf;
     422             :     }
     423             : 
     424             :     /*
     425             :      * Couldn't find a match in the database, so next we try constructed zone
     426             :      * names (like "PST8PDT").
     427             :      *
     428             :      * First we need to determine the names of the local standard and daylight
     429             :      * zones.  The idea here is to scan forward from today until we have seen
     430             :      * both zones, if both are in use.
     431             :      */
     432           0 :     memset(std_zone_name, 0, sizeof(std_zone_name));
     433           0 :     memset(dst_zone_name, 0, sizeof(dst_zone_name));
     434           0 :     std_ofs = 0;
     435             : 
     436           0 :     tnow = time(NULL);
     437             : 
     438             :     /*
     439             :      * Round back to a GMT midnight so results don't depend on local time of
     440             :      * day
     441             :      */
     442           0 :     tnow -= (tnow % T_DAY);
     443             : 
     444             :     /*
     445             :      * We have to look a little further ahead than one year, in case today is
     446             :      * just past a DST boundary that falls earlier in the year than the next
     447             :      * similar boundary.  Arbitrarily scan up to 14 months.
     448             :      */
     449           0 :     for (t = tnow; t <= tnow + T_MONTH * 14; t += T_MONTH)
     450             :     {
     451           0 :         tm = localtime(&t);
     452           0 :         if (!tm)
     453           0 :             continue;
     454           0 :         if (tm->tm_isdst < 0)
     455           0 :             continue;
     456           0 :         if (tm->tm_isdst == 0 && std_zone_name[0] == '\0')
     457             :         {
     458             :             /* found STD zone */
     459           0 :             memset(cbuf, 0, sizeof(cbuf));
     460           0 :             strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
     461           0 :             strcpy(std_zone_name, cbuf);
     462           0 :             std_ofs = get_timezone_offset(tm);
     463             :         }
     464           0 :         if (tm->tm_isdst > 0 && dst_zone_name[0] == '\0')
     465             :         {
     466             :             /* found DST zone */
     467           0 :             memset(cbuf, 0, sizeof(cbuf));
     468           0 :             strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
     469           0 :             strcpy(dst_zone_name, cbuf);
     470             :         }
     471             :         /* Done if found both */
     472           0 :         if (std_zone_name[0] && dst_zone_name[0])
     473           0 :             break;
     474             :     }
     475             : 
     476             :     /* We should have found a STD zone name by now... */
     477           0 :     if (std_zone_name[0] == '\0')
     478             :     {
     479             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     480             :         fprintf(stderr, "could not determine system time zone\n");
     481             : #endif
     482           0 :         return NULL;            /* go to GMT */
     483             :     }
     484             : 
     485             :     /* If we found DST then try STD<ofs>DST */
     486           0 :     if (dst_zone_name[0] != '\0')
     487             :     {
     488           0 :         snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
     489           0 :                  std_zone_name, -std_ofs / 3600, dst_zone_name);
     490           0 :         if (score_timezone(resultbuf, &tt) > 0)
     491           0 :             return resultbuf;
     492             :     }
     493             : 
     494             :     /* Try just the STD timezone (works for GMT at least) */
     495           0 :     strcpy(resultbuf, std_zone_name);
     496           0 :     if (score_timezone(resultbuf, &tt) > 0)
     497           0 :         return resultbuf;
     498             : 
     499             :     /* Try STD<ofs> */
     500           0 :     snprintf(resultbuf, sizeof(resultbuf), "%s%d",
     501           0 :              std_zone_name, -std_ofs / 3600);
     502           0 :     if (score_timezone(resultbuf, &tt) > 0)
     503           0 :         return resultbuf;
     504             : 
     505             :     /*
     506             :      * Did not find the timezone.  Fallback to use a GMT zone.  Note that the
     507             :      * IANA timezone database names the GMT-offset zones in POSIX style: plus
     508             :      * is west of Greenwich.  It's unfortunate that this is opposite of SQL
     509             :      * conventions.  Should we therefore change the names? Probably not...
     510             :      */
     511           0 :     snprintf(resultbuf, sizeof(resultbuf), "Etc/GMT%s%d",
     512           0 :              (-std_ofs > 0) ? "+" : "", -std_ofs / 3600);
     513             : 
     514             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     515             :     fprintf(stderr, "could not recognize system time zone, using \"%s\"\n",
     516             :             resultbuf);
     517             : #endif
     518           0 :     return resultbuf;
     519             : }
     520             : 
     521             : /*
     522             :  * Examine a system-provided symlink file to see if it tells us the timezone.
     523             :  *
     524             :  * Unfortunately, there is little standardization of how the system default
     525             :  * timezone is determined in the absence of a TZ environment setting.
     526             :  * But a common strategy is to create a symlink at a well-known place.
     527             :  * If "linkname" identifies a readable symlink, and the tail of its contents
     528             :  * matches a zone name we know, and the actual behavior of localtime() agrees
     529             :  * with what we think that zone means, then we may use that zone name.
     530             :  *
     531             :  * We insist on a perfect behavioral match, which might not happen if the
     532             :  * system has a different IANA database version than we do; but in that case
     533             :  * it seems best to fall back to the brute-force search.
     534             :  *
     535             :  * linkname is the symlink file location to probe.
     536             :  *
     537             :  * tt tells about the system timezone behavior we need to match.
     538             :  *
     539             :  * If we successfully identify a zone name, store it in *bestzonename and
     540             :  * return true; else return false.  bestzonename must be a buffer of length
     541             :  * TZ_STRLEN_MAX + 1.
     542             :  */
     543             : static bool
     544         482 : check_system_link_file(const char *linkname, struct tztry *tt,
     545             :                        char *bestzonename)
     546             : {
     547             : #ifdef HAVE_READLINK
     548             :     char        link_target[MAXPGPATH];
     549             :     int         len;
     550             :     const char *cur_name;
     551             : 
     552             :     /*
     553             :      * Try to read the symlink.  If not there, not a symlink, etc etc, just
     554             :      * quietly fail; the precise reason needn't concern us.
     555             :      */
     556         482 :     len = readlink(linkname, link_target, sizeof(link_target));
     557         482 :     if (len < 0 || len >= sizeof(link_target))
     558           0 :         return false;
     559         482 :     link_target[len] = '\0';
     560             : 
     561             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     562             :     fprintf(stderr, "symbolic link \"%s\" contains \"%s\"\n",
     563             :             linkname, link_target);
     564             : #endif
     565             : 
     566             :     /*
     567             :      * The symlink is probably of the form "/path/to/zones/zone/name", or
     568             :      * possibly it is a relative path.  Nobody puts their zone DB directly in
     569             :      * the root directory, so we can definitely skip the first component; but
     570             :      * after that it's trial-and-error to identify which path component begins
     571             :      * the zone name.
     572             :      */
     573         482 :     cur_name = link_target;
     574        1446 :     while (*cur_name)
     575             :     {
     576             :         /* Advance to next segment of path */
     577        1446 :         cur_name = strchr(cur_name + 1, '/');
     578        1446 :         if (cur_name == NULL)
     579           0 :             break;
     580             :         /* If there are consecutive slashes, skip all, as the kernel would */
     581             :         do
     582             :         {
     583        1446 :             cur_name++;
     584        1446 :         } while (*cur_name == '/');
     585             : 
     586             :         /*
     587             :          * Test remainder of path to see if it is a matching zone name.
     588             :          * Relative paths might contain ".."; we needn't bother testing if the
     589             :          * first component is that.  Also defend against overlength names.
     590             :          */
     591        1446 :         if (*cur_name && *cur_name != '.' &&
     592        2892 :             strlen(cur_name) <= TZ_STRLEN_MAX &&
     593        1446 :             perfect_timezone_match(cur_name, tt))
     594             :         {
     595             :             /* Success! */
     596         482 :             strcpy(bestzonename, cur_name);
     597         482 :             return true;
     598             :         }
     599             :     }
     600             : 
     601             :     /* Couldn't extract a matching zone name */
     602           0 :     return false;
     603             : #else
     604             :     /* No symlinks?  Forget it */
     605             :     return false;
     606             : #endif
     607             : }
     608             : 
     609             : /*
     610             :  * Given a timezone name, determine whether it should be preferred over other
     611             :  * names which are equally good matches. The output is arbitrary but we will
     612             :  * use 0 for "neutral" default preference; larger values are more preferred.
     613             :  */
     614             : static int
     615           0 : zone_name_pref(const char *zonename)
     616             : {
     617             :     /*
     618             :      * Prefer UTC over alternatives such as UCT.  Also prefer Etc/UTC over
     619             :      * Etc/UCT; but UTC is preferred to Etc/UTC.
     620             :      */
     621           0 :     if (strcmp(zonename, "UTC") == 0)
     622           0 :         return 50;
     623           0 :     if (strcmp(zonename, "Etc/UTC") == 0)
     624           0 :         return 40;
     625             : 
     626             :     /*
     627             :      * We don't want to pick "localtime" or "posixrules", unless we can find
     628             :      * no other name for the prevailing zone.  Those aren't real zone names.
     629             :      */
     630           0 :     if (strcmp(zonename, "localtime") == 0 ||
     631           0 :         strcmp(zonename, "posixrules") == 0)
     632           0 :         return -50;
     633             : 
     634           0 :     return 0;
     635             : }
     636             : 
     637             : /*
     638             :  * Recursively scan the timezone database looking for the best match to
     639             :  * the system timezone behavior.
     640             :  *
     641             :  * tzdir points to a buffer of size MAXPGPATH.  On entry, it holds the
     642             :  * pathname of a directory containing TZ files.  We internally modify it
     643             :  * to hold pathnames of sub-directories and files, but must restore it
     644             :  * to its original contents before exit.
     645             :  *
     646             :  * tzdirsub points to the part of tzdir that represents the subfile name
     647             :  * (ie, tzdir + the original directory name length, plus one for the
     648             :  * first added '/').
     649             :  *
     650             :  * tt tells about the system timezone behavior we need to match.
     651             :  *
     652             :  * *bestscore and *bestzonename on entry hold the best score found so far
     653             :  * and the name of the best zone.  We overwrite them if we find a better
     654             :  * score.  bestzonename must be a buffer of length TZ_STRLEN_MAX + 1.
     655             :  */
     656             : static void
     657           0 : scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt,
     658             :                          int *bestscore, char *bestzonename)
     659             : {
     660           0 :     int         tzdir_orig_len = strlen(tzdir);
     661             :     char      **names;
     662             :     char      **namep;
     663             : 
     664           0 :     names = pgfnames(tzdir);
     665           0 :     if (!names)
     666           0 :         return;
     667             : 
     668           0 :     for (namep = names; *namep; namep++)
     669             :     {
     670           0 :         char       *name = *namep;
     671             :         struct stat statbuf;
     672             : 
     673             :         /* Ignore . and .., plus any other "hidden" files */
     674           0 :         if (name[0] == '.')
     675           0 :             continue;
     676             : 
     677           0 :         snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
     678             :                  "/%s", name);
     679             : 
     680           0 :         if (stat(tzdir, &statbuf) != 0)
     681             :         {
     682             : #ifdef DEBUG_IDENTIFY_TIMEZONE
     683             :             fprintf(stderr, "could not stat \"%s\": %s\n",
     684             :                     tzdir, strerror(errno));
     685             : #endif
     686           0 :             tzdir[tzdir_orig_len] = '\0';
     687           0 :             continue;
     688             :         }
     689             : 
     690           0 :         if (S_ISDIR(statbuf.st_mode))
     691             :         {
     692             :             /* Recurse into subdirectory */
     693           0 :             scan_available_timezones(tzdir, tzdirsub, tt,
     694             :                                      bestscore, bestzonename);
     695             :         }
     696             :         else
     697             :         {
     698             :             /* Load and test this file */
     699           0 :             int         score = score_timezone(tzdirsub, tt);
     700             : 
     701           0 :             if (score > *bestscore)
     702             :             {
     703           0 :                 *bestscore = score;
     704           0 :                 strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
     705             :             }
     706           0 :             else if (score == *bestscore)
     707             :             {
     708             :                 /* Consider how to break a tie */
     709           0 :                 int         namepref = (zone_name_pref(tzdirsub) -
     710           0 :                                         zone_name_pref(bestzonename));
     711             : 
     712           0 :                 if (namepref > 0 ||
     713           0 :                     (namepref == 0 &&
     714           0 :                      (strlen(tzdirsub) < strlen(bestzonename) ||
     715           0 :                       (strlen(tzdirsub) == strlen(bestzonename) &&
     716           0 :                        strcmp(tzdirsub, bestzonename) < 0))))
     717           0 :                     strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
     718             :             }
     719             :         }
     720             : 
     721             :         /* Restore tzdir */
     722           0 :         tzdir[tzdir_orig_len] = '\0';
     723             :     }
     724             : 
     725           0 :     pgfnames_cleanup(names);
     726             : }
     727             : #else                           /* WIN32 */
     728             : 
     729             : static const struct
     730             : {
     731             :     const char *stdname;        /* Windows name of standard timezone */
     732             :     const char *dstname;        /* Windows name of daylight timezone */
     733             :     const char *pgtzname;       /* Name of pgsql timezone to map to */
     734             : }           win32_tzmap[] =
     735             : 
     736             : {
     737             :     /*
     738             :      * This list was built from the contents of the registry at
     739             :      * HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time
     740             :      * Zones on Windows 7, Windows 10, and Windows Server 2019.  Some recent
     741             :      * additions have been made by comparing to the CLDR project's
     742             :      * windowsZones.xml file.
     743             :      *
     744             :      * The zones have been matched to IANA timezones based on CLDR's mapping
     745             :      * for "territory 001".
     746             :      */
     747             :     {
     748             :         /* (UTC+04:30) Kabul */
     749             :         "Afghanistan Standard Time", "Afghanistan Daylight Time",
     750             :         "Asia/Kabul"
     751             :     },
     752             :     {
     753             :         /* (UTC-09:00) Alaska */
     754             :         "Alaskan Standard Time", "Alaskan Daylight Time",
     755             :         "America/Anchorage"
     756             :     },
     757             :     {
     758             :         /* (UTC-10:00) Aleutian Islands */
     759             :         "Aleutian Standard Time", "Aleutian Daylight Time",
     760             :         "America/Adak"
     761             :     },
     762             :     {
     763             :         /* (UTC+07:00) Barnaul, Gorno-Altaysk */
     764             :         "Altai Standard Time", "Altai Daylight Time",
     765             :         "Asia/Barnaul"
     766             :     },
     767             :     {
     768             :         /* (UTC+03:00) Kuwait, Riyadh */
     769             :         "Arab Standard Time", "Arab Daylight Time",
     770             :         "Asia/Riyadh"
     771             :     },
     772             :     {
     773             :         /* (UTC+04:00) Abu Dhabi, Muscat */
     774             :         "Arabian Standard Time", "Arabian Daylight Time",
     775             :         "Asia/Dubai"
     776             :     },
     777             :     {
     778             :         /* (UTC+03:00) Baghdad */
     779             :         "Arabic Standard Time", "Arabic Daylight Time",
     780             :         "Asia/Baghdad"
     781             :     },
     782             :     {
     783             :         /* (UTC-03:00) City of Buenos Aires */
     784             :         "Argentina Standard Time", "Argentina Daylight Time",
     785             :         "America/Buenos_Aires"
     786             :     },
     787             :     {
     788             :         /* (UTC+04:00) Baku, Tbilisi, Yerevan */
     789             :         "Armenian Standard Time", "Armenian Daylight Time",
     790             :         "Asia/Yerevan"
     791             :     },
     792             :     {
     793             :         /* (UTC+04:00) Astrakhan, Ulyanovsk */
     794             :         "Astrakhan Standard Time", "Astrakhan Daylight Time",
     795             :         "Europe/Astrakhan"
     796             :     },
     797             :     {
     798             :         /* (UTC-04:00) Atlantic Time (Canada) */
     799             :         "Atlantic Standard Time", "Atlantic Daylight Time",
     800             :         "America/Halifax"
     801             :     },
     802             :     {
     803             :         /* (UTC+09:30) Darwin */
     804             :         "AUS Central Standard Time", "AUS Central Daylight Time",
     805             :         "Australia/Darwin"
     806             :     },
     807             :     {
     808             :         /* (UTC+08:45) Eucla */
     809             :         "Aus Central W. Standard Time", "Aus Central W. Daylight Time",
     810             :         "Australia/Eucla"
     811             :     },
     812             :     {
     813             :         /* (UTC+10:00) Canberra, Melbourne, Sydney */
     814             :         "AUS Eastern Standard Time", "AUS Eastern Daylight Time",
     815             :         "Australia/Sydney"
     816             :     },
     817             :     {
     818             :         /* (UTC+04:00) Baku */
     819             :         "Azerbaijan Standard Time", "Azerbaijan Daylight Time",
     820             :         "Asia/Baku"
     821             :     },
     822             :     {
     823             :         /* (UTC-01:00) Azores */
     824             :         "Azores Standard Time", "Azores Daylight Time",
     825             :         "Atlantic/Azores"
     826             :     },
     827             :     {
     828             :         /* (UTC-03:00) Salvador */
     829             :         "Bahia Standard Time", "Bahia Daylight Time",
     830             :         "America/Bahia"
     831             :     },
     832             :     {
     833             :         /* (UTC+06:00) Dhaka */
     834             :         "Bangladesh Standard Time", "Bangladesh Daylight Time",
     835             :         "Asia/Dhaka"
     836             :     },
     837             :     {
     838             :         /* (UTC+03:00) Minsk */
     839             :         "Belarus Standard Time", "Belarus Daylight Time",
     840             :         "Europe/Minsk"
     841             :     },
     842             :     {
     843             :         /* (UTC+11:00) Bougainville Island */
     844             :         "Bougainville Standard Time", "Bougainville Daylight Time",
     845             :         "Pacific/Bougainville"
     846             :     },
     847             :     {
     848             :         /* (UTC-01:00) Cabo Verde Is. */
     849             :         "Cabo Verde Standard Time", "Cabo Verde Daylight Time",
     850             :         "Atlantic/Cape_Verde"
     851             :     },
     852             :     {
     853             :         /* (UTC-06:00) Saskatchewan */
     854             :         "Canada Central Standard Time", "Canada Central Daylight Time",
     855             :         "America/Regina"
     856             :     },
     857             :     {
     858             :         /* (UTC-01:00) Cape Verde Is. */
     859             :         "Cape Verde Standard Time", "Cape Verde Daylight Time",
     860             :         "Atlantic/Cape_Verde"
     861             :     },
     862             :     {
     863             :         /* (UTC+04:00) Yerevan */
     864             :         "Caucasus Standard Time", "Caucasus Daylight Time",
     865             :         "Asia/Yerevan"
     866             :     },
     867             :     {
     868             :         /* (UTC+09:30) Adelaide */
     869             :         "Cen. Australia Standard Time", "Cen. Australia Daylight Time",
     870             :         "Australia/Adelaide"
     871             :     },
     872             :     {
     873             :         /* (UTC-06:00) Central America */
     874             :         "Central America Standard Time", "Central America Daylight Time",
     875             :         "America/Guatemala"
     876             :     },
     877             :     {
     878             :         /* (UTC+06:00) Astana */
     879             :         "Central Asia Standard Time", "Central Asia Daylight Time",
     880             :         "Asia/Almaty"
     881             :     },
     882             :     {
     883             :         /* (UTC-04:00) Cuiaba */
     884             :         "Central Brazilian Standard Time", "Central Brazilian Daylight Time",
     885             :         "America/Cuiaba"
     886             :     },
     887             :     {
     888             :         /* (UTC+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague */
     889             :         "Central Europe Standard Time", "Central Europe Daylight Time",
     890             :         "Europe/Budapest"
     891             :     },
     892             :     {
     893             :         /* (UTC+01:00) Sarajevo, Skopje, Warsaw, Zagreb */
     894             :         "Central European Standard Time", "Central European Daylight Time",
     895             :         "Europe/Warsaw"
     896             :     },
     897             :     {
     898             :         /* (UTC+11:00) Solomon Is., New Caledonia */
     899             :         "Central Pacific Standard Time", "Central Pacific Daylight Time",
     900             :         "Pacific/Guadalcanal"
     901             :     },
     902             :     {
     903             :         /* (UTC-06:00) Central Time (US & Canada) */
     904             :         "Central Standard Time", "Central Daylight Time",
     905             :         "America/Chicago"
     906             :     },
     907             :     {
     908             :         /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */
     909             :         "Central Standard Time (Mexico)", "Central Daylight Time (Mexico)",
     910             :         "America/Mexico_City"
     911             :     },
     912             :     {
     913             :         /* (UTC+12:45) Chatham Islands */
     914             :         "Chatham Islands Standard Time", "Chatham Islands Daylight Time",
     915             :         "Pacific/Chatham"
     916             :     },
     917             :     {
     918             :         /* (UTC+08:00) Beijing, Chongqing, Hong Kong, Urumqi */
     919             :         "China Standard Time", "China Daylight Time",
     920             :         "Asia/Shanghai"
     921             :     },
     922             :     {
     923             :         /* (UTC) Coordinated Universal Time */
     924             :         "Coordinated Universal Time", "Coordinated Universal Time",
     925             :         "UTC"
     926             :     },
     927             :     {
     928             :         /* (UTC-05:00) Havana */
     929             :         "Cuba Standard Time", "Cuba Daylight Time",
     930             :         "America/Havana"
     931             :     },
     932             :     {
     933             :         /* (UTC-12:00) International Date Line West */
     934             :         "Dateline Standard Time", "Dateline Daylight Time",
     935             :         "Etc/GMT+12"
     936             :     },
     937             :     {
     938             :         /* (UTC+03:00) Nairobi */
     939             :         "E. Africa Standard Time", "E. Africa Daylight Time",
     940             :         "Africa/Nairobi"
     941             :     },
     942             :     {
     943             :         /* (UTC+10:00) Brisbane */
     944             :         "E. Australia Standard Time", "E. Australia Daylight Time",
     945             :         "Australia/Brisbane"
     946             :     },
     947             :     {
     948             :         /* (UTC+02:00) Chisinau */
     949             :         "E. Europe Standard Time", "E. Europe Daylight Time",
     950             :         "Europe/Chisinau"
     951             :     },
     952             :     {
     953             :         /* (UTC-03:00) Brasilia */
     954             :         "E. South America Standard Time", "E. South America Daylight Time",
     955             :         "America/Sao_Paulo"
     956             :     },
     957             :     {
     958             :         /* (UTC-06:00) Easter Island */
     959             :         "Easter Island Standard Time", "Easter Island Daylight Time",
     960             :         "Pacific/Easter"
     961             :     },
     962             :     {
     963             :         /* (UTC-05:00) Eastern Time (US & Canada) */
     964             :         "Eastern Standard Time", "Eastern Daylight Time",
     965             :         "America/New_York"
     966             :     },
     967             :     {
     968             :         /* (UTC-05:00) Chetumal */
     969             :         "Eastern Standard Time (Mexico)", "Eastern Daylight Time (Mexico)",
     970             :         "America/Cancun"
     971             :     },
     972             :     {
     973             :         /* (UTC+02:00) Cairo */
     974             :         "Egypt Standard Time", "Egypt Daylight Time",
     975             :         "Africa/Cairo"
     976             :     },
     977             :     {
     978             :         /* (UTC+05:00) Ekaterinburg */
     979             :         "Ekaterinburg Standard Time", "Ekaterinburg Daylight Time",
     980             :         "Asia/Yekaterinburg"
     981             :     },
     982             :     {
     983             :         /* (UTC+12:00) Fiji */
     984             :         "Fiji Standard Time", "Fiji Daylight Time",
     985             :         "Pacific/Fiji"
     986             :     },
     987             :     {
     988             :         /* (UTC+02:00) Helsinki, Kyiv, Riga, Sofia, Tallinn, Vilnius */
     989             :         "FLE Standard Time", "FLE Daylight Time",
     990             :         "Europe/Kiev"
     991             :     },
     992             :     {
     993             :         /* (UTC+04:00) Tbilisi */
     994             :         "Georgian Standard Time", "Georgian Daylight Time",
     995             :         "Asia/Tbilisi"
     996             :     },
     997             :     {
     998             :         /* (UTC+00:00) Dublin, Edinburgh, Lisbon, London */
     999             :         "GMT Standard Time", "GMT Daylight Time",
    1000             :         "Europe/London"
    1001             :     },
    1002             :     {
    1003             :         /* (UTC-03:00) Greenland */
    1004             :         "Greenland Standard Time", "Greenland Daylight Time",
    1005             :         "America/Godthab"
    1006             :     },
    1007             :     {
    1008             :         /*
    1009             :          * Windows uses this zone name in various places that lie near the
    1010             :          * prime meridian, but are not in the UK.  However, most people
    1011             :          * probably think that "Greenwich" means UK civil time, or maybe even
    1012             :          * straight-up UTC.  Atlantic/Reykjavik is a decent match for that
    1013             :          * interpretation because Iceland hasn't observed DST since 1968.
    1014             :          */
    1015             :         /* (UTC+00:00) Monrovia, Reykjavik */
    1016             :         "Greenwich Standard Time", "Greenwich Daylight Time",
    1017             :         "Atlantic/Reykjavik"
    1018             :     },
    1019             :     {
    1020             :         /* (UTC+02:00) Athens, Bucharest */
    1021             :         "GTB Standard Time", "GTB Daylight Time",
    1022             :         "Europe/Bucharest"
    1023             :     },
    1024             :     {
    1025             :         /* (UTC-05:00) Haiti */
    1026             :         "Haiti Standard Time", "Haiti Daylight Time",
    1027             :         "America/Port-au-Prince"
    1028             :     },
    1029             :     {
    1030             :         /* (UTC-10:00) Hawaii */
    1031             :         "Hawaiian Standard Time", "Hawaiian Daylight Time",
    1032             :         "Pacific/Honolulu"
    1033             :     },
    1034             :     {
    1035             :         /* (UTC+05:30) Chennai, Kolkata, Mumbai, New Delhi */
    1036             :         "India Standard Time", "India Daylight Time",
    1037             :         "Asia/Calcutta"
    1038             :     },
    1039             :     {
    1040             :         /* (UTC+03:30) Tehran */
    1041             :         "Iran Standard Time", "Iran Daylight Time",
    1042             :         "Asia/Tehran"
    1043             :     },
    1044             :     {
    1045             :         /* (UTC+02:00) Jerusalem */
    1046             :         "Israel Standard Time", "Israel Daylight Time",
    1047             :         "Asia/Jerusalem"
    1048             :     },
    1049             :     {
    1050             :         /* (UTC+02:00) Jerusalem (old spelling of zone name) */
    1051             :         "Jerusalem Standard Time", "Jerusalem Daylight Time",
    1052             :         "Asia/Jerusalem"
    1053             :     },
    1054             :     {
    1055             :         /* (UTC+02:00) Amman */
    1056             :         "Jordan Standard Time", "Jordan Daylight Time",
    1057             :         "Asia/Amman"
    1058             :     },
    1059             :     {
    1060             :         /* (UTC+02:00) Kaliningrad */
    1061             :         "Kaliningrad Standard Time", "Kaliningrad Daylight Time",
    1062             :         "Europe/Kaliningrad"
    1063             :     },
    1064             :     {
    1065             :         /* (UTC+12:00) Petropavlovsk-Kamchatsky - Old */
    1066             :         "Kamchatka Standard Time", "Kamchatka Daylight Time",
    1067             :         "Asia/Kamchatka"
    1068             :     },
    1069             :     {
    1070             :         /* (UTC+09:00) Seoul */
    1071             :         "Korea Standard Time", "Korea Daylight Time",
    1072             :         "Asia/Seoul"
    1073             :     },
    1074             :     {
    1075             :         /* (UTC+02:00) Tripoli */
    1076             :         "Libya Standard Time", "Libya Daylight Time",
    1077             :         "Africa/Tripoli"
    1078             :     },
    1079             :     {
    1080             :         /* (UTC+14:00) Kiritimati Island */
    1081             :         "Line Islands Standard Time", "Line Islands Daylight Time",
    1082             :         "Pacific/Kiritimati"
    1083             :     },
    1084             :     {
    1085             :         /* (UTC+10:30) Lord Howe Island */
    1086             :         "Lord Howe Standard Time", "Lord Howe Daylight Time",
    1087             :         "Australia/Lord_Howe"
    1088             :     },
    1089             :     {
    1090             :         /* (UTC+11:00) Magadan */
    1091             :         "Magadan Standard Time", "Magadan Daylight Time",
    1092             :         "Asia/Magadan"
    1093             :     },
    1094             :     {
    1095             :         /* (UTC-03:00) Punta Arenas */
    1096             :         "Magallanes Standard Time", "Magallanes Daylight Time",
    1097             :         "America/Punta_Arenas"
    1098             :     },
    1099             :     {
    1100             :         /* (UTC+08:00) Kuala Lumpur, Singapore */
    1101             :         "Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
    1102             :         "Asia/Kuala_Lumpur"
    1103             :     },
    1104             :     {
    1105             :         /* (UTC-09:30) Marquesas Islands */
    1106             :         "Marquesas Standard Time", "Marquesas Daylight Time",
    1107             :         "Pacific/Marquesas"
    1108             :     },
    1109             :     {
    1110             :         /* (UTC+04:00) Port Louis */
    1111             :         "Mauritius Standard Time", "Mauritius Daylight Time",
    1112             :         "Indian/Mauritius"
    1113             :     },
    1114             :     {
    1115             :         /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */
    1116             :         "Mexico Standard Time", "Mexico Daylight Time",
    1117             :         "America/Mexico_City"
    1118             :     },
    1119             :     {
    1120             :         /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
    1121             :         "Mexico Standard Time 2", "Mexico Daylight Time 2",
    1122             :         "America/Chihuahua"
    1123             :     },
    1124             :     {
    1125             :         /* (UTC-02:00) Mid-Atlantic - Old */
    1126             :         "Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
    1127             :         "Atlantic/South_Georgia"
    1128             :     },
    1129             :     {
    1130             :         /* (UTC+02:00) Beirut */
    1131             :         "Middle East Standard Time", "Middle East Daylight Time",
    1132             :         "Asia/Beirut"
    1133             :     },
    1134             :     {
    1135             :         /* (UTC-03:00) Montevideo */
    1136             :         "Montevideo Standard Time", "Montevideo Daylight Time",
    1137             :         "America/Montevideo"
    1138             :     },
    1139             :     {
    1140             :         /* (UTC+01:00) Casablanca */
    1141             :         "Morocco Standard Time", "Morocco Daylight Time",
    1142             :         "Africa/Casablanca"
    1143             :     },
    1144             :     {
    1145             :         /* (UTC-07:00) Mountain Time (US & Canada) */
    1146             :         "Mountain Standard Time", "Mountain Daylight Time",
    1147             :         "America/Denver"
    1148             :     },
    1149             :     {
    1150             :         /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
    1151             :         "Mountain Standard Time (Mexico)", "Mountain Daylight Time (Mexico)",
    1152             :         "America/Chihuahua"
    1153             :     },
    1154             :     {
    1155             :         /* (UTC+06:30) Yangon (Rangoon) */
    1156             :         "Myanmar Standard Time", "Myanmar Daylight Time",
    1157             :         "Asia/Rangoon"
    1158             :     },
    1159             :     {
    1160             :         /* (UTC+07:00) Novosibirsk */
    1161             :         "N. Central Asia Standard Time", "N. Central Asia Daylight Time",
    1162             :         "Asia/Novosibirsk"
    1163             :     },
    1164             :     {
    1165             :         /* (UTC+02:00) Windhoek */
    1166             :         "Namibia Standard Time", "Namibia Daylight Time",
    1167             :         "Africa/Windhoek"
    1168             :     },
    1169             :     {
    1170             :         /* (UTC+05:45) Kathmandu */
    1171             :         "Nepal Standard Time", "Nepal Daylight Time",
    1172             :         "Asia/Katmandu"
    1173             :     },
    1174             :     {
    1175             :         /* (UTC+12:00) Auckland, Wellington */
    1176             :         "New Zealand Standard Time", "New Zealand Daylight Time",
    1177             :         "Pacific/Auckland"
    1178             :     },
    1179             :     {
    1180             :         /* (UTC-03:30) Newfoundland */
    1181             :         "Newfoundland Standard Time", "Newfoundland Daylight Time",
    1182             :         "America/St_Johns"
    1183             :     },
    1184             :     {
    1185             :         /* (UTC+11:00) Norfolk Island */
    1186             :         "Norfolk Standard Time", "Norfolk Daylight Time",
    1187             :         "Pacific/Norfolk"
    1188             :     },
    1189             :     {
    1190             :         /* (UTC+08:00) Irkutsk */
    1191             :         "North Asia East Standard Time", "North Asia East Daylight Time",
    1192             :         "Asia/Irkutsk"
    1193             :     },
    1194             :     {
    1195             :         /* (UTC+07:00) Krasnoyarsk */
    1196             :         "North Asia Standard Time", "North Asia Daylight Time",
    1197             :         "Asia/Krasnoyarsk"
    1198             :     },
    1199             :     {
    1200             :         /* (UTC+09:00) Pyongyang */
    1201             :         "North Korea Standard Time", "North Korea Daylight Time",
    1202             :         "Asia/Pyongyang"
    1203             :     },
    1204             :     {
    1205             :         /* (UTC+07:00) Novosibirsk */
    1206             :         "Novosibirsk Standard Time", "Novosibirsk Daylight Time",
    1207             :         "Asia/Novosibirsk"
    1208             :     },
    1209             :     {
    1210             :         /* (UTC+06:00) Omsk */
    1211             :         "Omsk Standard Time", "Omsk Daylight Time",
    1212             :         "Asia/Omsk"
    1213             :     },
    1214             :     {
    1215             :         /* (UTC-04:00) Santiago */
    1216             :         "Pacific SA Standard Time", "Pacific SA Daylight Time",
    1217             :         "America/Santiago"
    1218             :     },
    1219             :     {
    1220             :         /* (UTC-08:00) Pacific Time (US & Canada) */
    1221             :         "Pacific Standard Time", "Pacific Daylight Time",
    1222             :         "America/Los_Angeles"
    1223             :     },
    1224             :     {
    1225             :         /* (UTC-08:00) Baja California */
    1226             :         "Pacific Standard Time (Mexico)", "Pacific Daylight Time (Mexico)",
    1227             :         "America/Tijuana"
    1228             :     },
    1229             :     {
    1230             :         /* (UTC+05:00) Islamabad, Karachi */
    1231             :         "Pakistan Standard Time", "Pakistan Daylight Time",
    1232             :         "Asia/Karachi"
    1233             :     },
    1234             :     {
    1235             :         /* (UTC-04:00) Asuncion */
    1236             :         "Paraguay Standard Time", "Paraguay Daylight Time",
    1237             :         "America/Asuncion"
    1238             :     },
    1239             :     {
    1240             :         /* (UTC+05:00) Qyzylorda */
    1241             :         "Qyzylorda Standard Time", "Qyzylorda Daylight Time",
    1242             :         "Asia/Qyzylorda"
    1243             :     },
    1244             :     {
    1245             :         /* (UTC+01:00) Brussels, Copenhagen, Madrid, Paris */
    1246             :         "Romance Standard Time", "Romance Daylight Time",
    1247             :         "Europe/Paris"
    1248             :     },
    1249             :     {
    1250             :         /* (UTC+04:00) Izhevsk, Samara */
    1251             :         "Russia Time Zone 3", "Russia Time Zone 3",
    1252             :         "Europe/Samara"
    1253             :     },
    1254             :     {
    1255             :         /* (UTC+11:00) Chokurdakh */
    1256             :         "Russia Time Zone 10", "Russia Time Zone 10",
    1257             :         "Asia/Srednekolymsk"
    1258             :     },
    1259             :     {
    1260             :         /* (UTC+12:00) Anadyr, Petropavlovsk-Kamchatsky */
    1261             :         "Russia Time Zone 11", "Russia Time Zone 11",
    1262             :         "Asia/Kamchatka"
    1263             :     },
    1264             :     {
    1265             :         /* (UTC+02:00) Kaliningrad */
    1266             :         "Russia TZ 1 Standard Time", "Russia TZ 1 Daylight Time",
    1267             :         "Europe/Kaliningrad"
    1268             :     },
    1269             :     {
    1270             :         /* (UTC+03:00) Moscow, St. Petersburg */
    1271             :         "Russia TZ 2 Standard Time", "Russia TZ 2 Daylight Time",
    1272             :         "Europe/Moscow"
    1273             :     },
    1274             :     {
    1275             :         /* (UTC+04:00) Izhevsk, Samara */
    1276             :         "Russia TZ 3 Standard Time", "Russia TZ 3 Daylight Time",
    1277             :         "Europe/Samara"
    1278             :     },
    1279             :     {
    1280             :         /* (UTC+05:00) Ekaterinburg */
    1281             :         "Russia TZ 4 Standard Time", "Russia TZ 4 Daylight Time",
    1282             :         "Asia/Yekaterinburg"
    1283             :     },
    1284             :     {
    1285             :         /* (UTC+06:00) Novosibirsk (RTZ 5) */
    1286             :         "Russia TZ 5 Standard Time", "Russia TZ 5 Daylight Time",
    1287             :         "Asia/Novosibirsk"
    1288             :     },
    1289             :     {
    1290             :         /* (UTC+07:00) Krasnoyarsk */
    1291             :         "Russia TZ 6 Standard Time", "Russia TZ 6 Daylight Time",
    1292             :         "Asia/Krasnoyarsk"
    1293             :     },
    1294             :     {
    1295             :         /* (UTC+08:00) Irkutsk */
    1296             :         "Russia TZ 7 Standard Time", "Russia TZ 7 Daylight Time",
    1297             :         "Asia/Irkutsk"
    1298             :     },
    1299             :     {
    1300             :         /* (UTC+09:00) Yakutsk */
    1301             :         "Russia TZ 8 Standard Time", "Russia TZ 8 Daylight Time",
    1302             :         "Asia/Yakutsk"
    1303             :     },
    1304             :     {
    1305             :         /* (UTC+10:00) Vladivostok */
    1306             :         "Russia TZ 9 Standard Time", "Russia TZ 9 Daylight Time",
    1307             :         "Asia/Vladivostok"
    1308             :     },
    1309             :     {
    1310             :         /* (UTC+11:00) Chokurdakh */
    1311             :         "Russia TZ 10 Standard Time", "Russia TZ 10 Daylight Time",
    1312             :         "Asia/Magadan"
    1313             :     },
    1314             :     {
    1315             :         /* (UTC+12:00) Anadyr, Petropavlovsk-Kamchatsky */
    1316             :         "Russia TZ 11 Standard Time", "Russia TZ 11 Daylight Time",
    1317             :         "Asia/Anadyr"
    1318             :     },
    1319             :     {
    1320             :         /* (UTC+03:00) Moscow, St. Petersburg */
    1321             :         "Russian Standard Time", "Russian Daylight Time",
    1322             :         "Europe/Moscow"
    1323             :     },
    1324             :     {
    1325             :         /* (UTC-03:00) Cayenne, Fortaleza */
    1326             :         "SA Eastern Standard Time", "SA Eastern Daylight Time",
    1327             :         "America/Cayenne"
    1328             :     },
    1329             :     {
    1330             :         /* (UTC-05:00) Bogota, Lima, Quito, Rio Branco */
    1331             :         "SA Pacific Standard Time", "SA Pacific Daylight Time",
    1332             :         "America/Bogota"
    1333             :     },
    1334             :     {
    1335             :         /* (UTC-04:00) Georgetown, La Paz, Manaus, San Juan */
    1336             :         "SA Western Standard Time", "SA Western Daylight Time",
    1337             :         "America/La_Paz"
    1338             :     },
    1339             :     {
    1340             :         /* (UTC-03:00) Saint Pierre and Miquelon */
    1341             :         "Saint Pierre Standard Time", "Saint Pierre Daylight Time",
    1342             :         "America/Miquelon"
    1343             :     },
    1344             :     {
    1345             :         /* (UTC+11:00) Sakhalin */
    1346             :         "Sakhalin Standard Time", "Sakhalin Daylight Time",
    1347             :         "Asia/Sakhalin"
    1348             :     },
    1349             :     {
    1350             :         /* (UTC+13:00) Samoa */
    1351             :         "Samoa Standard Time", "Samoa Daylight Time",
    1352             :         "Pacific/Apia"
    1353             :     },
    1354             :     {
    1355             :         /* (UTC+00:00) Sao Tome */
    1356             :         "Sao Tome Standard Time", "Sao Tome Daylight Time",
    1357             :         "Africa/Sao_Tome"
    1358             :     },
    1359             :     {
    1360             :         /* (UTC+04:00) Saratov */
    1361             :         "Saratov Standard Time", "Saratov Daylight Time",
    1362             :         "Europe/Saratov"
    1363             :     },
    1364             :     {
    1365             :         /* (UTC+07:00) Bangkok, Hanoi, Jakarta */
    1366             :         "SE Asia Standard Time", "SE Asia Daylight Time",
    1367             :         "Asia/Bangkok"
    1368             :     },
    1369             :     {
    1370             :         /* (UTC+08:00) Kuala Lumpur, Singapore */
    1371             :         "Singapore Standard Time", "Singapore Daylight Time",
    1372             :         "Asia/Singapore"
    1373             :     },
    1374             :     {
    1375             :         /* (UTC+02:00) Harare, Pretoria */
    1376             :         "South Africa Standard Time", "South Africa Daylight Time",
    1377             :         "Africa/Johannesburg"
    1378             :     },
    1379             :     {
    1380             :         /* (UTC+02:00) Juba */
    1381             :         "South Sudan Standard Time", "South Sudan Daylight Time",
    1382             :         "Africa/Juba"
    1383             :     },
    1384             :     {
    1385             :         /* (UTC+05:30) Sri Jayawardenepura */
    1386             :         "Sri Lanka Standard Time", "Sri Lanka Daylight Time",
    1387             :         "Asia/Colombo"
    1388             :     },
    1389             :     {
    1390             :         /* (UTC+02:00) Khartoum */
    1391             :         "Sudan Standard Time", "Sudan Daylight Time",
    1392             :         "Africa/Khartoum"
    1393             :     },
    1394             :     {
    1395             :         /* (UTC+02:00) Damascus */
    1396             :         "Syria Standard Time", "Syria Daylight Time",
    1397             :         "Asia/Damascus"
    1398             :     },
    1399             :     {
    1400             :         /* (UTC+08:00) Taipei */
    1401             :         "Taipei Standard Time", "Taipei Daylight Time",
    1402             :         "Asia/Taipei"
    1403             :     },
    1404             :     {
    1405             :         /* (UTC+10:00) Hobart */
    1406             :         "Tasmania Standard Time", "Tasmania Daylight Time",
    1407             :         "Australia/Hobart"
    1408             :     },
    1409             :     {
    1410             :         /* (UTC-03:00) Araguaina */
    1411             :         "Tocantins Standard Time", "Tocantins Daylight Time",
    1412             :         "America/Araguaina"
    1413             :     },
    1414             :     {
    1415             :         /* (UTC+09:00) Osaka, Sapporo, Tokyo */
    1416             :         "Tokyo Standard Time", "Tokyo Daylight Time",
    1417             :         "Asia/Tokyo"
    1418             :     },
    1419             :     {
    1420             :         /* (UTC+07:00) Tomsk */
    1421             :         "Tomsk Standard Time", "Tomsk Daylight Time",
    1422             :         "Asia/Tomsk"
    1423             :     },
    1424             :     {
    1425             :         /* (UTC+13:00) Nuku'alofa */
    1426             :         "Tonga Standard Time", "Tonga Daylight Time",
    1427             :         "Pacific/Tongatapu"
    1428             :     },
    1429             :     {
    1430             :         /* (UTC+09:00) Chita */
    1431             :         "Transbaikal Standard Time", "Transbaikal Daylight Time",
    1432             :         "Asia/Chita"
    1433             :     },
    1434             :     {
    1435             :         /* (UTC+03:00) Istanbul */
    1436             :         "Turkey Standard Time", "Turkey Daylight Time",
    1437             :         "Europe/Istanbul"
    1438             :     },
    1439             :     {
    1440             :         /* (UTC-05:00) Turks and Caicos */
    1441             :         "Turks And Caicos Standard Time", "Turks And Caicos Daylight Time",
    1442             :         "America/Grand_Turk"
    1443             :     },
    1444             :     {
    1445             :         /* (UTC+08:00) Ulaanbaatar */
    1446             :         "Ulaanbaatar Standard Time", "Ulaanbaatar Daylight Time",
    1447             :         "Asia/Ulaanbaatar"
    1448             :     },
    1449             :     {
    1450             :         /* (UTC-05:00) Indiana (East) */
    1451             :         "US Eastern Standard Time", "US Eastern Daylight Time",
    1452             :         "America/Indianapolis"
    1453             :     },
    1454             :     {
    1455             :         /* (UTC-07:00) Arizona */
    1456             :         "US Mountain Standard Time", "US Mountain Daylight Time",
    1457             :         "America/Phoenix"
    1458             :     },
    1459             :     {
    1460             :         /* (UTC) Coordinated Universal Time */
    1461             :         "UTC", "UTC",
    1462             :         "UTC"
    1463             :     },
    1464             :     {
    1465             :         /* (UTC+12:00) Coordinated Universal Time+12 */
    1466             :         "UTC+12", "UTC+12",
    1467             :         "Etc/GMT-12"
    1468             :     },
    1469             :     {
    1470             :         /* (UTC+13:00) Coordinated Universal Time+13 */
    1471             :         "UTC+13", "UTC+13",
    1472             :         "Etc/GMT-13"
    1473             :     },
    1474             :     {
    1475             :         /* (UTC-02:00) Coordinated Universal Time-02 */
    1476             :         "UTC-02", "UTC-02",
    1477             :         "Etc/GMT+2"
    1478             :     },
    1479             :     {
    1480             :         /* (UTC-08:00) Coordinated Universal Time-08 */
    1481             :         "UTC-08", "UTC-08",
    1482             :         "Etc/GMT+8"
    1483             :     },
    1484             :     {
    1485             :         /* (UTC-09:00) Coordinated Universal Time-09 */
    1486             :         "UTC-09", "UTC-09",
    1487             :         "Etc/GMT+9"
    1488             :     },
    1489             :     {
    1490             :         /* (UTC-11:00) Coordinated Universal Time-11 */
    1491             :         "UTC-11", "UTC-11",
    1492             :         "Etc/GMT+11"
    1493             :     },
    1494             :     {
    1495             :         /* (UTC-04:00) Caracas */
    1496             :         "Venezuela Standard Time", "Venezuela Daylight Time",
    1497             :         "America/Caracas"
    1498             :     },
    1499             :     {
    1500             :         /* (UTC+10:00) Vladivostok */
    1501             :         "Vladivostok Standard Time", "Vladivostok Daylight Time",
    1502             :         "Asia/Vladivostok"
    1503             :     },
    1504             :     {
    1505             :         /* (UTC+04:00) Volgograd */
    1506             :         "Volgograd Standard Time", "Volgograd Daylight Time",
    1507             :         "Europe/Volgograd"
    1508             :     },
    1509             :     {
    1510             :         /* (UTC+08:00) Perth */
    1511             :         "W. Australia Standard Time", "W. Australia Daylight Time",
    1512             :         "Australia/Perth"
    1513             :     },
    1514             :     {
    1515             :         /* (UTC+01:00) West Central Africa */
    1516             :         "W. Central Africa Standard Time", "W. Central Africa Daylight Time",
    1517             :         "Africa/Lagos"
    1518             :     },
    1519             :     {
    1520             :         /* (UTC+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna */
    1521             :         "W. Europe Standard Time", "W. Europe Daylight Time",
    1522             :         "Europe/Berlin"
    1523             :     },
    1524             :     {
    1525             :         /* (UTC+07:00) Hovd */
    1526             :         "W. Mongolia Standard Time", "W. Mongolia Daylight Time",
    1527             :         "Asia/Hovd"
    1528             :     },
    1529             :     {
    1530             :         /* (UTC+05:00) Ashgabat, Tashkent */
    1531             :         "West Asia Standard Time", "West Asia Daylight Time",
    1532             :         "Asia/Tashkent"
    1533             :     },
    1534             :     {
    1535             :         /* (UTC+02:00) Gaza, Hebron */
    1536             :         "West Bank Gaza Standard Time", "West Bank Gaza Daylight Time",
    1537             :         "Asia/Gaza"
    1538             :     },
    1539             :     {
    1540             :         /* (UTC+02:00) Gaza, Hebron */
    1541             :         "West Bank Standard Time", "West Bank Daylight Time",
    1542             :         "Asia/Hebron"
    1543             :     },
    1544             :     {
    1545             :         /* (UTC+10:00) Guam, Port Moresby */
    1546             :         "West Pacific Standard Time", "West Pacific Daylight Time",
    1547             :         "Pacific/Port_Moresby"
    1548             :     },
    1549             :     {
    1550             :         /* (UTC+09:00) Yakutsk */
    1551             :         "Yakutsk Standard Time", "Yakutsk Daylight Time",
    1552             :         "Asia/Yakutsk"
    1553             :     },
    1554             :     {
    1555             :         /* (UTC-07:00) Yukon */
    1556             :         "Yukon Standard Time", "Yukon Daylight Time",
    1557             :         "America/Whitehorse"
    1558             :     },
    1559             :     {
    1560             :         NULL, NULL, NULL
    1561             :     }
    1562             : };
    1563             : 
    1564             : static const char *
    1565             : identify_system_timezone(void)
    1566             : {
    1567             :     int         i;
    1568             :     char        tzname[128];
    1569             :     char        localtzname[256];
    1570             :     time_t      t = time(NULL);
    1571             :     struct tm  *tm = localtime(&t);
    1572             :     HKEY        rootKey;
    1573             :     int         idx;
    1574             : 
    1575             :     if (!tm)
    1576             :     {
    1577             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1578             :         fprintf(stderr, "could not identify system time zone: localtime() failed\n");
    1579             : #endif
    1580             :         return NULL;            /* go to GMT */
    1581             :     }
    1582             : 
    1583             :     memset(tzname, 0, sizeof(tzname));
    1584             :     strftime(tzname, sizeof(tzname) - 1, "%Z", tm);
    1585             : 
    1586             :     for (i = 0; win32_tzmap[i].stdname != NULL; i++)
    1587             :     {
    1588             :         if (strcmp(tzname, win32_tzmap[i].stdname) == 0 ||
    1589             :             strcmp(tzname, win32_tzmap[i].dstname) == 0)
    1590             :         {
    1591             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1592             :             fprintf(stderr, "TZ \"%s\" matches system time zone \"%s\"\n",
    1593             :                     win32_tzmap[i].pgtzname, tzname);
    1594             : #endif
    1595             :             return win32_tzmap[i].pgtzname;
    1596             :         }
    1597             :     }
    1598             : 
    1599             :     /*
    1600             :      * Localized Windows versions return localized names for the timezone.
    1601             :      * Scan the registry to find the English name, and then try matching
    1602             :      * against our table again.
    1603             :      */
    1604             :     memset(localtzname, 0, sizeof(localtzname));
    1605             :     if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
    1606             :                      "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
    1607             :                      0,
    1608             :                      KEY_READ,
    1609             :                      &rootKey) != ERROR_SUCCESS)
    1610             :     {
    1611             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1612             :         fprintf(stderr, "could not open registry key to identify system time zone: error code %lu\n",
    1613             :                 GetLastError());
    1614             : #endif
    1615             :         return NULL;            /* go to GMT */
    1616             :     }
    1617             : 
    1618             :     for (idx = 0;; idx++)
    1619             :     {
    1620             :         char        keyname[256];
    1621             :         char        zonename[256];
    1622             :         DWORD       namesize;
    1623             :         FILETIME    lastwrite;
    1624             :         HKEY        key;
    1625             :         LONG        r;
    1626             : 
    1627             :         memset(keyname, 0, sizeof(keyname));
    1628             :         namesize = sizeof(keyname);
    1629             :         if ((r = RegEnumKeyEx(rootKey,
    1630             :                               idx,
    1631             :                               keyname,
    1632             :                               &namesize,
    1633             :                               NULL,
    1634             :                               NULL,
    1635             :                               NULL,
    1636             :                               &lastwrite)) != ERROR_SUCCESS)
    1637             :         {
    1638             :             if (r == ERROR_NO_MORE_ITEMS)
    1639             :                 break;
    1640             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1641             :             fprintf(stderr, "could not enumerate registry subkeys to identify system time zone: %d\n",
    1642             :                     (int) r);
    1643             : #endif
    1644             :             break;
    1645             :         }
    1646             : 
    1647             :         if ((r = RegOpenKeyEx(rootKey, keyname, 0, KEY_READ, &key)) != ERROR_SUCCESS)
    1648             :         {
    1649             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1650             :             fprintf(stderr, "could not open registry subkey to identify system time zone: %d\n",
    1651             :                     (int) r);
    1652             : #endif
    1653             :             break;
    1654             :         }
    1655             : 
    1656             :         memset(zonename, 0, sizeof(zonename));
    1657             :         namesize = sizeof(zonename);
    1658             :         if ((r = RegQueryValueEx(key, "Std", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
    1659             :         {
    1660             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1661             :             fprintf(stderr, "could not query value for key \"std\" to identify system time zone \"%s\": %d\n",
    1662             :                     keyname, (int) r);
    1663             : #endif
    1664             :             RegCloseKey(key);
    1665             :             continue;           /* Proceed to look at the next timezone */
    1666             :         }
    1667             :         if (strcmp(tzname, zonename) == 0)
    1668             :         {
    1669             :             /* Matched zone */
    1670             :             strcpy(localtzname, keyname);
    1671             :             RegCloseKey(key);
    1672             :             break;
    1673             :         }
    1674             :         memset(zonename, 0, sizeof(zonename));
    1675             :         namesize = sizeof(zonename);
    1676             :         if ((r = RegQueryValueEx(key, "Dlt", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
    1677             :         {
    1678             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1679             :             fprintf(stderr, "could not query value for key \"dlt\" to identify system time zone \"%s\": %d\n",
    1680             :                     keyname, (int) r);
    1681             : #endif
    1682             :             RegCloseKey(key);
    1683             :             continue;           /* Proceed to look at the next timezone */
    1684             :         }
    1685             :         if (strcmp(tzname, zonename) == 0)
    1686             :         {
    1687             :             /* Matched DST zone */
    1688             :             strcpy(localtzname, keyname);
    1689             :             RegCloseKey(key);
    1690             :             break;
    1691             :         }
    1692             : 
    1693             :         RegCloseKey(key);
    1694             :     }
    1695             : 
    1696             :     RegCloseKey(rootKey);
    1697             : 
    1698             :     if (localtzname[0])
    1699             :     {
    1700             :         /* Found a localized name, so scan for that one too */
    1701             :         for (i = 0; win32_tzmap[i].stdname != NULL; i++)
    1702             :         {
    1703             :             if (strcmp(localtzname, win32_tzmap[i].stdname) == 0 ||
    1704             :                 strcmp(localtzname, win32_tzmap[i].dstname) == 0)
    1705             :             {
    1706             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1707             :                 fprintf(stderr, "TZ \"%s\" matches localized system time zone \"%s\" (\"%s\")\n",
    1708             :                         win32_tzmap[i].pgtzname, tzname, localtzname);
    1709             : #endif
    1710             :                 return win32_tzmap[i].pgtzname;
    1711             :             }
    1712             :         }
    1713             :     }
    1714             : 
    1715             : #ifdef DEBUG_IDENTIFY_TIMEZONE
    1716             :     fprintf(stderr, "could not find a match for system time zone \"%s\"\n",
    1717             :             tzname);
    1718             : #endif
    1719             :     return NULL;                /* go to GMT */
    1720             : }
    1721             : #endif                          /* WIN32 */
    1722             : 
    1723             : 
    1724             : /*
    1725             :  * Return true if the given zone name is valid and is an "acceptable" zone.
    1726             :  */
    1727             : static bool
    1728         964 : validate_zone(const char *tzname)
    1729             : {
    1730             :     pg_tz      *tz;
    1731             : 
    1732         964 :     if (!tzname || !tzname[0])
    1733         482 :         return false;
    1734             : 
    1735         482 :     tz = pg_load_tz(tzname);
    1736         482 :     if (!tz)
    1737           0 :         return false;
    1738             : 
    1739         482 :     if (!pg_tz_acceptable(tz))
    1740           0 :         return false;
    1741             : 
    1742         482 :     return true;
    1743             : }
    1744             : 
    1745             : /*
    1746             :  * Identify a suitable default timezone setting based on the environment.
    1747             :  *
    1748             :  * The installation share_path must be passed in, as that is the default
    1749             :  * location for the timezone database directory.
    1750             :  *
    1751             :  * We first look to the TZ environment variable.  If not found or not
    1752             :  * recognized by our own code, we see if we can identify the timezone
    1753             :  * from the behavior of the system timezone library.  When all else fails,
    1754             :  * return NULL, indicating that we should default to GMT.
    1755             :  */
    1756             : const char *
    1757         482 : select_default_timezone(const char *share_path)
    1758             : {
    1759             :     const char *tzname;
    1760             : 
    1761             :     /* Initialize timezone directory path, if needed */
    1762             : #ifndef SYSTEMTZDIR
    1763         482 :     snprintf(tzdirpath, sizeof(tzdirpath), "%s/timezone", share_path);
    1764             : #endif
    1765             : 
    1766             :     /* Check TZ environment variable */
    1767         482 :     tzname = getenv("TZ");
    1768         482 :     if (validate_zone(tzname))
    1769           0 :         return tzname;
    1770             : 
    1771             :     /* Nope, so try to identify the system timezone */
    1772         482 :     tzname = identify_system_timezone();
    1773         482 :     if (validate_zone(tzname))
    1774         482 :         return tzname;
    1775             : 
    1776           0 :     return NULL;
    1777             : }

Generated by: LCOV version 1.14