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findtimezone.c
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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 pg_TZDIR(void)
38 {
39 #ifndef SYSTEMTZDIR
40  /* normal case: timezone stuff is under our share dir */
41  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 pg_open_tzfile(const char *name, char *canonname)
66 {
67  char fullname[MAXPGPATH];
68 
69  if (canonname)
70  strlcpy(canonname, name, TZ_STRLEN_MAX + 1);
71 
72  strlcpy(fullname, pg_TZDIR(), sizeof(fullname));
73  if (strlen(fullname) + 1 + strlen(name) >= MAXPGPATH)
74  return -1; /* not gonna fit */
75  strcat(fullname, "/");
76  strcat(fullname, name);
77 
78  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 pg_load_tz(const char *name)
92 {
93  static pg_tz tz;
94 
95  if (strlen(name) > TZ_STRLEN_MAX)
96  return NULL; /* not going to fit */
97 
98  /*
99  * "GMT" is always sent to tzparse(); see comments for pg_tzset().
100  */
101  if (strcmp(name, "GMT") == 0)
102  {
103  if (!tzparse(name, &tz.state, true))
104  {
105  /* This really, really should not happen ... */
106  return NULL;
107  }
108  }
109  else if (tzload(name, NULL, &tz.state, true) != 0)
110  {
111  if (name[0] == ':' || !tzparse(name, &tz.state, false))
112  {
113  return NULL; /* unknown timezone */
114  }
115  }
116 
117  strcpy(tz.TZname, name);
118 
119  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 {
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
176 {
177 #if defined(HAVE_STRUCT_TM_TM_ZONE)
178  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 build_time_t(int year, int month, int day)
191 {
192  struct tm tm;
193 
194  memset(&tm, 0, sizeof(tm));
195  tm.tm_mday = day;
196  tm.tm_mon = month - 1;
197  tm.tm_year = year - 1900;
198  tm.tm_isdst = -1;
199 
200  return mktime(&tm);
201 }
202 
203 /*
204  * Does a system tm value match one we computed ourselves?
205  */
206 static bool
207 compare_tm(struct tm *s, struct pg_tm *p)
208 {
209  if (s->tm_sec != p->tm_sec ||
210  s->tm_min != p->tm_min ||
211  s->tm_hour != p->tm_hour ||
212  s->tm_mday != p->tm_mday ||
213  s->tm_mon != p->tm_mon ||
214  s->tm_year != p->tm_year ||
215  s->tm_wday != p->tm_wday ||
216  s->tm_yday != p->tm_yday ||
217  s->tm_isdst != p->tm_isdst)
218  return false;
219  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 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  tz = pg_load_tz(tzname);
245  if (!tz)
246  return -1; /* unrecognized zone name */
247 
248  /* Reject if leap seconds involved */
249  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  return -1;
255  }
256 
257  /* Check for match at all the test times */
258  for (i = 0; i < tt->n_test_times; i++)
259  {
260  pgtt = (pg_time_t) (tt->test_times[i]);
261  pgtm = pg_localtime(&pgtt, tz);
262  if (!pgtm)
263  return -1; /* probably shouldn't happen */
264  systm = localtime(&(tt->test_times[i]));
265  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  return i;
275  }
276  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  return i;
289  }
290  if (systm->tm_isdst >= 0)
291  {
292  /* Check match of zone names, too */
293  if (pgtm->tm_zone == NULL)
294  return -1; /* probably shouldn't happen */
295  memset(cbuf, 0, sizeof(cbuf));
296  strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm); /* zone abbr */
297  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  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  return i;
314 }
315 
316 /*
317  * Test whether given zone name is a perfect match to localtime() behavior
318  */
319 static bool
320 perfect_timezone_match(const char *tzname, struct tztry *tt)
321 {
322  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 *
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  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  tnow = time(NULL);
369  tm = localtime(&tnow);
370  if (!tm)
371  return NULL; /* give up if localtime is broken... */
372  thisyear = tm->tm_year + 1900;
373 
374  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  t -= (t % T_WEEK);
383 
384  tt.n_test_times = 0;
385  tt.test_times[tt.n_test_times++] = t;
386 
387  t = build_time_t(thisyear, 7, 15);
388  t -= (t % T_WEEK);
389 
390  tt.test_times[tt.n_test_times++] = t;
391 
392  while (tt.n_test_times < MAX_TEST_TIMES)
393  {
394  t -= T_WEEK;
395  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  if (check_system_link_file("/etc/localtime", &tt, resultbuf))
407  return resultbuf;
408 
409  /* No luck, so search for the best-matching timezone file */
410  strlcpy(tmptzdir, pg_TZDIR(), sizeof(tmptzdir));
411  bestscore = -1;
412  resultbuf[0] = '\0';
413  scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1,
414  &tt,
415  &bestscore, resultbuf);
416  if (bestscore > 0)
417  {
418  /* Ignore IANA's rather silly "Factory" zone; use GMT instead */
419  if (strcmp(resultbuf, "Factory") == 0)
420  return NULL;
421  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  memset(std_zone_name, 0, sizeof(std_zone_name));
433  memset(dst_zone_name, 0, sizeof(dst_zone_name));
434  std_ofs = 0;
435 
436  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  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  for (t = tnow; t <= tnow + T_MONTH * 14; t += T_MONTH)
450  {
451  tm = localtime(&t);
452  if (!tm)
453  continue;
454  if (tm->tm_isdst < 0)
455  continue;
456  if (tm->tm_isdst == 0 && std_zone_name[0] == '\0')
457  {
458  /* found STD zone */
459  memset(cbuf, 0, sizeof(cbuf));
460  strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
461  strcpy(std_zone_name, cbuf);
462  std_ofs = get_timezone_offset(tm);
463  }
464  if (tm->tm_isdst > 0 && dst_zone_name[0] == '\0')
465  {
466  /* found DST zone */
467  memset(cbuf, 0, sizeof(cbuf));
468  strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
469  strcpy(dst_zone_name, cbuf);
470  }
471  /* Done if found both */
472  if (std_zone_name[0] && dst_zone_name[0])
473  break;
474  }
475 
476  /* We should have found a STD zone name by now... */
477  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  return NULL; /* go to GMT */
483  }
484 
485  /* If we found DST then try STD<ofs>DST */
486  if (dst_zone_name[0] != '\0')
487  {
488  snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
489  std_zone_name, -std_ofs / 3600, dst_zone_name);
490  if (score_timezone(resultbuf, &tt) > 0)
491  return resultbuf;
492  }
493 
494  /* Try just the STD timezone (works for GMT at least) */
495  strcpy(resultbuf, std_zone_name);
496  if (score_timezone(resultbuf, &tt) > 0)
497  return resultbuf;
498 
499  /* Try STD<ofs> */
500  snprintf(resultbuf, sizeof(resultbuf), "%s%d",
501  std_zone_name, -std_ofs / 3600);
502  if (score_timezone(resultbuf, &tt) > 0)
503  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  snprintf(resultbuf, sizeof(resultbuf), "Etc/GMT%s%d",
512  (-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  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 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  len = readlink(linkname, link_target, sizeof(link_target));
557  if (len < 0 || len >= sizeof(link_target))
558  return false;
559  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  cur_name = link_target;
574  while (*cur_name)
575  {
576  /* Advance to next segment of path */
577  cur_name = strchr(cur_name + 1, '/');
578  if (cur_name == NULL)
579  break;
580  /* If there are consecutive slashes, skip all, as the kernel would */
581  do
582  {
583  cur_name++;
584  } 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  if (*cur_name && *cur_name != '.' &&
592  strlen(cur_name) <= TZ_STRLEN_MAX &&
593  perfect_timezone_match(cur_name, tt))
594  {
595  /* Success! */
596  strcpy(bestzonename, cur_name);
597  return true;
598  }
599  }
600 
601  /* Couldn't extract a matching zone name */
602  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 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  if (strcmp(zonename, "UTC") == 0)
622  return 50;
623  if (strcmp(zonename, "Etc/UTC") == 0)
624  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  if (strcmp(zonename, "localtime") == 0 ||
631  strcmp(zonename, "posixrules") == 0)
632  return -50;
633 
634  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 scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt,
658  int *bestscore, char *bestzonename)
659 {
660  int tzdir_orig_len = strlen(tzdir);
661  char **names;
662  char **namep;
663 
664  names = pgfnames(tzdir);
665  if (!names)
666  return;
667 
668  for (namep = names; *namep; namep++)
669  {
670  char *name = *namep;
671  struct stat statbuf;
672 
673  /* Ignore . and .., plus any other "hidden" files */
674  if (name[0] == '.')
675  continue;
676 
677  snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
678  "/%s", name);
679 
680  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  tzdir[tzdir_orig_len] = '\0';
687  continue;
688  }
689 
690  if (S_ISDIR(statbuf.st_mode))
691  {
692  /* Recurse into subdirectory */
693  scan_available_timezones(tzdir, tzdirsub, tt,
694  bestscore, bestzonename);
695  }
696  else
697  {
698  /* Load and test this file */
699  int score = score_timezone(tzdirsub, tt);
700 
701  if (score > *bestscore)
702  {
703  *bestscore = score;
704  strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
705  }
706  else if (score == *bestscore)
707  {
708  /* Consider how to break a tie */
709  int namepref = (zone_name_pref(tzdirsub) -
710  zone_name_pref(bestzonename));
711 
712  if (namepref > 0 ||
713  (namepref == 0 &&
714  (strlen(tzdirsub) < strlen(bestzonename) ||
715  (strlen(tzdirsub) == strlen(bestzonename) &&
716  strcmp(tzdirsub, bestzonename) < 0))))
717  strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
718  }
719  }
720 
721  /* Restore tzdir */
722  tzdir[tzdir_orig_len] = '\0';
723  }
724 
725  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 *
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 validate_zone(const char *tzname)
1729 {
1730  pg_tz *tz;
1731 
1732  if (!tzname || !tzname[0])
1733  return false;
1734 
1735  tz = pg_load_tz(tzname);
1736  if (!tz)
1737  return false;
1738 
1739  if (!pg_tz_acceptable(tz))
1740  return false;
1741 
1742  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 *
1758 {
1759  const char *tzname;
1760 
1761  /* Initialize timezone directory path, if needed */
1762 #ifndef SYSTEMTZDIR
1763  snprintf(tzdirpath, sizeof(tzdirpath), "%s/timezone", share_path);
1764 #endif
1765 
1766  /* Check TZ environment variable */
1767  tzname = getenv("TZ");
1768  if (validate_zone(tzname))
1769  return tzname;
1770 
1771  /* Nope, so try to identify the system timezone */
1772  tzname = identify_system_timezone();
1773  if (validate_zone(tzname))
1774  return tzname;
1775 
1776  return NULL;
1777 }
#define T_DAY
Definition: findtimezone.c:152
const char * select_default_timezone(const char *share_path)
char ** pgfnames(const char *path)
Definition: pgfnames.c:37
static bool validate_zone(const char *tzname)
int64 pg_time_t
Definition: pgtime.h:23
int tm_wday
Definition: pgtime.h:40
static void scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt, int *bestscore, char *bestzonename)
Definition: findtimezone.c:657
int tm_isdst
Definition: pgtime.h:42
int tzload(const char *name, char *canonname, struct state *sp, bool doextend)
Definition: localtime.c:584
int tm_hour
Definition: pgtime.h:36
#define TIMEZONE_GLOBAL
Definition: port.h:247
#define T_MONTH
Definition: findtimezone.c:154
time_t test_times[MAX_TEST_TIMES]
Definition: findtimezone.c:161
Datum idx(PG_FUNCTION_ARGS)
Definition: _int_op.c:259
Definition: pgtime.h:32
static pg_tz * pg_load_tz(const char *name)
Definition: findtimezone.c:91
#define fprintf
Definition: port.h:221
static const char * pg_TZDIR(void)
Definition: findtimezone.c:37
#define PG_BINARY
Definition: c.h:1271
static int zone_name_pref(const char *zonename)
Definition: findtimezone.c:615
static char * share_path
Definition: initdb.c:121
static struct pg_tm tm
Definition: localtime.c:102
#define TZ_STRLEN_MAX
Definition: pgtime.h:51
#define MAXPGPATH
static bool compare_tm(struct tm *s, struct pg_tm *p)
Definition: findtimezone.c:207
static bool perfect_timezone_match(const char *tzname, struct tztry *tt)
Definition: findtimezone.c:320
int tm_mday
Definition: pgtime.h:37
int tm_mon
Definition: pgtime.h:38
#define readlink(path, buf, size)
Definition: win32_port.h:236
int n_test_times
Definition: findtimezone.c:160
static int get_timezone_offset(struct tm *tm)
Definition: findtimezone.c:175
static time_t build_time_t(int year, int month, int day)
Definition: findtimezone.c:190
const char * tm_zone
Definition: pgtime.h:44
bool tzparse(const char *name, struct state *sp, bool lastditch)
Definition: localtime.c:934
#define T_WEEK
Definition: findtimezone.c:153
static int score_timezone(const char *tzname, struct tztry *tt)
Definition: findtimezone.c:234
static char tzdirpath[MAXPGPATH]
Definition: findtimezone.c:27
bool pg_tz_acceptable(pg_tz *tz)
Definition: localtime.c:1888
struct state state
Definition: pgtz.h:69
unsigned short st_mode
Definition: win32_port.h:268
Definition: pgtz.h:65
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
void pgfnames_cleanup(char **filenames)
Definition: pgfnames.c:86
#define strerror
Definition: port.h:230
char TZname[TZ_STRLEN_MAX+1]
Definition: pgtz.h:68
static bool check_system_link_file(const char *linkname, struct tztry *tt, char *bestzonename)
Definition: findtimezone.c:544
struct pg_tm * pg_localtime(const pg_time_t *timep, const pg_tz *tz)
Definition: localtime.c:1342
const char * name
Definition: encode.c:561
#define S_ISDIR(m)
Definition: win32_port.h:324
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Definition: pgtime.h:39
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static const char * identify_system_timezone(void)
Definition: findtimezone.c:331
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Definition: findtimezone.c:65
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Definition: pgtime.h:41
int tm_sec
Definition: pgtime.h:34
#define snprintf
Definition: port.h:217
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Definition: pgtime.h:35
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Definition: win32_port.h:283
#define MAX_TEST_TIMES
Definition: findtimezone.c:156