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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.
741  *
742  * The zones have been matched to IANA timezones by looking at the cities
743  * listed in the win32 display name (in the comment here) in most cases.
744  */
745  {
746  /* (UTC+04:30) Kabul */
747  "Afghanistan Standard Time", "Afghanistan Daylight Time",
748  "Asia/Kabul"
749  },
750  {
751  /* (UTC-09:00) Alaska */
752  "Alaskan Standard Time", "Alaskan Daylight Time",
753  "US/Alaska"
754  },
755  {
756  /* (UTC-10:00) Aleutian Islands */
757  "Aleutian Standard Time", "Aleutian Daylight Time",
758  "US/Aleutan"
759  },
760  {
761  /* (UTC+07:00) Barnaul, Gorno-Altaysk */
762  "Altai Standard Time", "Altai Daylight Time",
763  "Asia/Barnaul"
764  },
765  {
766  /* (UTC+03:00) Kuwait, Riyadh */
767  "Arab Standard Time", "Arab Daylight Time",
768  "Asia/Kuwait"
769  },
770  {
771  /* (UTC+04:00) Abu Dhabi, Muscat */
772  "Arabian Standard Time", "Arabian Daylight Time",
773  "Asia/Muscat"
774  },
775  {
776  /* (UTC+03:00) Baghdad */
777  "Arabic Standard Time", "Arabic Daylight Time",
778  "Asia/Baghdad"
779  },
780  {
781  /* (UTC-03:00) City of Buenos Aires */
782  "Argentina Standard Time", "Argentina Daylight Time",
783  "America/Buenos_Aires"
784  },
785  {
786  /* (UTC+04:00) Baku, Tbilisi, Yerevan */
787  "Armenian Standard Time", "Armenian Daylight Time",
788  "Asia/Yerevan"
789  },
790  {
791  /* (UTC+04:00) Astrakhan, Ulyanovsk */
792  "Astrakhan Standard Time", "Astrakhan Daylight Time",
793  "Europe/Astrakhan"
794  },
795  {
796  /* (UTC-04:00) Atlantic Time (Canada) */
797  "Atlantic Standard Time", "Atlantic Daylight Time",
798  "Canada/Atlantic"
799  },
800  {
801  /* (UTC+09:30) Darwin */
802  "AUS Central Standard Time", "AUS Central Daylight Time",
803  "Australia/Darwin"
804  },
805  {
806  /* (UTC+08:45) Eucla */
807  "Aus Central W. Standard Time", "Aus Central W. Daylight Time",
808  "Australia/Eucla"
809  },
810  {
811  /* (UTC+10:00) Canberra, Melbourne, Sydney */
812  "AUS Eastern Standard Time", "AUS Eastern Daylight Time",
813  "Australia/Canberra"
814  },
815  {
816  /* (UTC+04:00) Baku */
817  "Azerbaijan Standard Time", "Azerbaijan Daylight Time",
818  "Asia/Baku"
819  },
820  {
821  /* (UTC-01:00) Azores */
822  "Azores Standard Time", "Azores Daylight Time",
823  "Atlantic/Azores"
824  },
825  {
826  /* (UTC-03:00) Salvador */
827  "Bahia Standard Time", "Bahia Daylight Time",
828  "America/Salvador"
829  },
830  {
831  /* (UTC+06:00) Dhaka */
832  "Bangladesh Standard Time", "Bangladesh Daylight Time",
833  "Asia/Dhaka"
834  },
835  {
836  /* (UTC+11:00) Bougainville Island */
837  "Bougainville Standard Time", "Bougainville Daylight Time",
838  "Pacific/Bougainville"
839  },
840  {
841  /* (UTC+03:00) Minsk */
842  "Belarus Standard Time", "Belarus Daylight Time",
843  "Europe/Minsk"
844  },
845  {
846  /* (UTC-01:00) Cabo Verde Is. */
847  "Cabo Verde Standard Time", "Cabo Verde Daylight Time",
848  "Atlantic/Cape_Verde"
849  },
850  {
851  /* (UTC+12:45) Chatham Islands */
852  "Chatham Islands Standard Time", "Chatham Islands Daylight Time",
853  "Pacific/Chatham"
854  },
855  {
856  /* (UTC-06:00) Saskatchewan */
857  "Canada Central Standard Time", "Canada Central Daylight Time",
858  "Canada/Saskatchewan"
859  },
860  {
861  /* (UTC-01:00) Cape Verde Is. */
862  "Cape Verde Standard Time", "Cape Verde Daylight Time",
863  "Atlantic/Cape_Verde"
864  },
865  {
866  /* (UTC+04:00) Yerevan */
867  "Caucasus Standard Time", "Caucasus Daylight Time",
868  "Asia/Baku"
869  },
870  {
871  /* (UTC+09:30) Adelaide */
872  "Cen. Australia Standard Time", "Cen. Australia Daylight Time",
873  "Australia/Adelaide"
874  },
875  /* Central America (other than Mexico) generally does not observe DST */
876  {
877  /* (UTC-06:00) Central America */
878  "Central America Standard Time", "Central America Daylight Time",
879  "CST6"
880  },
881  {
882  /* (UTC+06:00) Astana */
883  "Central Asia Standard Time", "Central Asia Daylight Time",
884  "Asia/Dhaka"
885  },
886  {
887  /* (UTC-04:00) Cuiaba */
888  "Central Brazilian Standard Time", "Central Brazilian Daylight Time",
889  "America/Cuiaba"
890  },
891  {
892  /* (UTC+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague */
893  "Central Europe Standard Time", "Central Europe Daylight Time",
894  "Europe/Belgrade"
895  },
896  {
897  /* (UTC+01:00) Sarajevo, Skopje, Warsaw, Zagreb */
898  "Central European Standard Time", "Central European Daylight Time",
899  "Europe/Sarajevo"
900  },
901  {
902  /* (UTC+11:00) Solomon Is., New Caledonia */
903  "Central Pacific Standard Time", "Central Pacific Daylight Time",
904  "Pacific/Noumea"
905  },
906  {
907  /* (UTC-06:00) Central Time (US & Canada) */
908  "Central Standard Time", "Central Daylight Time",
909  "US/Central"
910  },
911  {
912  /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */
913  "Central Standard Time (Mexico)", "Central Daylight Time (Mexico)",
914  "America/Mexico_City"
915  },
916  {
917  /* (UTC+08:00) Beijing, Chongqing, Hong Kong, Urumqi */
918  "China Standard Time", "China Daylight Time",
919  "Asia/Hong_Kong"
920  },
921  {
922  /* (UTC-05:00) Havana */
923  "Cuba Standard Time", "Cuba Daylight Time",
924  "America/Havana"
925  },
926  {
927  /* (UTC-12:00) International Date Line West */
928  "Dateline Standard Time", "Dateline Daylight Time",
929  "Etc/UTC+12"
930  },
931  {
932  /* (UTC+03:00) Nairobi */
933  "E. Africa Standard Time", "E. Africa Daylight Time",
934  "Africa/Nairobi"
935  },
936  {
937  /* (UTC+10:00) Brisbane */
938  "E. Australia Standard Time", "E. Australia Daylight Time",
939  "Australia/Brisbane"
940  },
941  {
942  /* (UTC+02:00) Chisinau */
943  "E. Europe Standard Time", "E. Europe Daylight Time",
944  "Europe/Bucharest"
945  },
946  {
947  /* (UTC-03:00) Brasilia */
948  "E. South America Standard Time", "E. South America Daylight Time",
949  "America/Araguaina"
950  },
951  {
952  /* (UTC-05:00) Eastern Time (US & Canada) */
953  "Eastern Standard Time", "Eastern Daylight Time",
954  "US/Eastern"
955  },
956  {
957  /* (UTC-05:00) Chetumal */
958  "Eastern Standard Time (Mexico)", "Eastern Daylight Time (Mexico)",
959  "America/Mexico_City"
960  },
961  {
962  /* (UTC-06:00) Easter Island */
963  "Easter Island Standard Time", "Easter Island Daylight Time",
964  "Pacific/Easter"
965  },
966  {
967  /* (UTC+02:00) Cairo */
968  "Egypt Standard Time", "Egypt Daylight Time",
969  "Africa/Cairo"
970  },
971  {
972  /* (UTC+05:00) Ekaterinburg */
973  "Ekaterinburg Standard Time (RTZ 4)", "Ekaterinburg Daylight Time",
974  "Asia/Yekaterinburg"
975  },
976  {
977  /* (UTC+12:00) Fiji */
978  "Fiji Standard Time", "Fiji Daylight Time",
979  "Pacific/Fiji"
980  },
981  {
982  /* (UTC+02:00) Helsinki, Kyiv, Riga, Sofia, Tallinn, Vilnius */
983  "FLE Standard Time", "FLE Daylight Time",
984  "Europe/Helsinki"
985  },
986  {
987  /* (UTC+04:00) Tbilisi */
988  "Georgian Standard Time", "Georgian Daylight Time",
989  "Asia/Tbilisi"
990  },
991  {
992  /* (UTC+00:00) Dublin, Edinburgh, Lisbon, London */
993  "GMT Standard Time", "GMT Daylight Time",
994  "Europe/London"
995  },
996  {
997  /* (UTC-03:00) Greenland */
998  "Greenland Standard Time", "Greenland Daylight Time",
999  "America/Godthab"
1000  },
1001  {
1002  /* (UTC+00:00) Monrovia, Reykjavik */
1003  "Greenwich Standard Time", "Greenwich Daylight Time",
1004  "Africa/Casablanca"
1005  },
1006  {
1007  /* (UTC+02:00) Athens, Bucharest */
1008  "GTB Standard Time", "GTB Daylight Time",
1009  "Europe/Athens"
1010  },
1011  {
1012  /* (UTC-05:00) Haiti */
1013  "Haiti Standard Time", "Haiti Daylight Time",
1014  "US/Eastern"
1015  },
1016  {
1017  /* (UTC-10:00) Hawaii */
1018  "Hawaiian Standard Time", "Hawaiian Daylight Time",
1019  "US/Hawaii"
1020  },
1021  {
1022  /* (UTC+05:30) Chennai, Kolkata, Mumbai, New Delhi */
1023  "India Standard Time", "India Daylight Time",
1024  "Asia/Calcutta"
1025  },
1026  {
1027  /* (UTC+03:30) Tehran */
1028  "Iran Standard Time", "Iran Daylight Time",
1029  "Asia/Tehran"
1030  },
1031  {
1032  /* (UTC+02:00) Jerusalem */
1033  "Jerusalem Standard Time", "Jerusalem Daylight Time",
1034  "Asia/Jerusalem"
1035  },
1036  {
1037  /* (UTC+02:00) Amman */
1038  "Jordan Standard Time", "Jordan Daylight Time",
1039  "Asia/Amman"
1040  },
1041  {
1042  /* (UTC+12:00) Petropavlovsk-Kamchatsky - Old */
1043  "Kamchatka Standard Time", "Kamchatka Daylight Time",
1044  "Asia/Kamchatka"
1045  },
1046  {
1047  /* (UTC+09:00) Seoul */
1048  "Korea Standard Time", "Korea Daylight Time",
1049  "Asia/Seoul"
1050  },
1051  {
1052  /* (UTC+02:00) Tripoli */
1053  "Libya Standard Time", "Libya Daylight Time",
1054  "Africa/Tripoli"
1055  },
1056  {
1057  /* (UTC+14:00) Kiritimati Island */
1058  "Line Islands Standard Time", "Line Islands Daylight Time",
1059  "Pacific/Kiritimati"
1060  },
1061  {
1062  /* (UTC+10:30) Lord Howe Island */
1063  "Lord Howe Standard Time", "Lord Howe Daylight Time",
1064  "Australia/Lord_Howe"
1065  },
1066  {
1067  /* (UTC+11:00) Magadan */
1068  "Magadan Standard Time", "Magadan Daylight Time",
1069  "Asia/Magadan"
1070  },
1071  {
1072  /* (UTC-03:00) Punta Arenas */
1073  "Magallanes Standard Time", "Magallanes Daylight Time",
1074  "America/Punta_Arenas"
1075  },
1076  {
1077  /* (UTC-09:30) Marquesas Islands */
1078  "Marquesas Standard Time", "Marquesas Daylight Time",
1079  "Pacific/Marquesas"
1080  },
1081  {
1082  /* (UTC+04:00) Port Louis */
1083  "Mauritius Standard Time", "Mauritius Daylight Time",
1084  "Indian/Mauritius"
1085  },
1086  {
1087  /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */
1088  "Mexico Standard Time", "Mexico Daylight Time",
1089  "America/Mexico_City"
1090  },
1091  {
1092  /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
1093  "Mexico Standard Time 2", "Mexico Daylight Time 2",
1094  "America/Chihuahua"
1095  },
1096  {
1097  /* (UTC-02:00) Mid-Atlantic - Old */
1098  "Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
1099  "Atlantic/South_Georgia"
1100  },
1101  {
1102  /* (UTC+02:00) Beirut */
1103  "Middle East Standard Time", "Middle East Daylight Time",
1104  "Asia/Beirut"
1105  },
1106  {
1107  /* (UTC-03:00) Montevideo */
1108  "Montevideo Standard Time", "Montevideo Daylight Time",
1109  "America/Montevideo"
1110  },
1111  {
1112  /* (UTC+01:00) Casablanca */
1113  "Morocco Standard Time", "Morocco Daylight Time",
1114  "Africa/Casablanca"
1115  },
1116  {
1117  /* (UTC-07:00) Mountain Time (US & Canada) */
1118  "Mountain Standard Time", "Mountain Daylight Time",
1119  "US/Mountain"
1120  },
1121  {
1122  /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
1123  "Mountain Standard Time (Mexico)", "Mountain Daylight Time (Mexico)",
1124  "America/Chihuahua"
1125  },
1126  {
1127  /* (UTC+06:30) Yangon (Rangoon) */
1128  "Myanmar Standard Time", "Myanmar Daylight Time",
1129  "Asia/Rangoon"
1130  },
1131  {
1132  /* (UTC+06:00) Novosibirsk (RTZ 5) */
1133  "N. Central Asia Standard Time", "N. Central Asia Daylight Time",
1134  "Asia/Novosibirsk"
1135  },
1136  {
1137  /* (UTC+02:00) Windhoek */
1138  "Namibia Standard Time", "Namibia Daylight Time",
1139  "Africa/Windhoek"
1140  },
1141  {
1142  /* (UTC+05:45) Kathmandu */
1143  "Nepal Standard Time", "Nepal Daylight Time",
1144  "Asia/Katmandu"
1145  },
1146  {
1147  /* (UTC+12:00) Auckland, Wellington */
1148  "New Zealand Standard Time", "New Zealand Daylight Time",
1149  "Pacific/Auckland"
1150  },
1151  {
1152  /* (UTC-03:30) Newfoundland */
1153  "Newfoundland Standard Time", "Newfoundland Daylight Time",
1154  "Canada/Newfoundland"
1155  },
1156  {
1157  /* (UTC+11:00) Norfolk Island */
1158  "Norfolk Standard Time", "Norfolk Daylight Time",
1159  "Pacific/Norfolk"
1160  },
1161  {
1162  /* (UTC+08:00) Irkutsk, Ulaan Bataar */
1163  "North Asia East Standard Time", "North Asia East Daylight Time",
1164  "Asia/Irkutsk"
1165  },
1166  {
1167  /* (UTC+07:00) Krasnoyarsk */
1168  "North Asia Standard Time", "North Asia Daylight Time",
1169  "Asia/Krasnoyarsk"
1170  },
1171  {
1172  /* (UTC+09:00) Pyongyang */
1173  "North Korea Standard Time", "North Korea Daylight Time",
1174  "Asia/Pyongyang"
1175  },
1176  {
1177  /* (UTC+07:00) Novosibirsk */
1178  "Novosibirsk Standard Time", "Novosibirsk Daylight Time",
1179  "Asia/Novosibirsk"
1180  },
1181  {
1182  /* (UTC+06:00) Omsk */
1183  "Omsk Standard Time", "Omsk Daylight Time",
1184  "Asia/Omsk"
1185  },
1186  {
1187  /* (UTC-04:00) Santiago */
1188  "Pacific SA Standard Time", "Pacific SA Daylight Time",
1189  "America/Santiago"
1190  },
1191  {
1192  /* (UTC-08:00) Pacific Time (US & Canada) */
1193  "Pacific Standard Time", "Pacific Daylight Time",
1194  "US/Pacific"
1195  },
1196  {
1197  /* (UTC-08:00) Baja California */
1198  "Pacific Standard Time (Mexico)", "Pacific Daylight Time (Mexico)",
1199  "America/Tijuana"
1200  },
1201  {
1202  /* (UTC+05:00) Islamabad, Karachi */
1203  "Pakistan Standard Time", "Pakistan Daylight Time",
1204  "Asia/Karachi"
1205  },
1206  {
1207  /* (UTC-04:00) Asuncion */
1208  "Paraguay Standard Time", "Paraguay Daylight Time",
1209  "America/Asuncion"
1210  },
1211  {
1212  /* (UTC+05:00) Qyzylorda */
1213  "Qyzylorda Standard Time", "Qyzylorda Daylight Time",
1214  "Asia/Qyzylorda"
1215  },
1216  {
1217  /* (UTC+01:00) Brussels, Copenhagen, Madrid, Paris */
1218  "Romance Standard Time", "Romance Daylight Time",
1219  "Europe/Brussels"
1220  },
1221  {
1222  /* (UTC+02:00) Kaliningrad */
1223  "Russia TZ 1 Standard Time", "Russia TZ 1 Daylight Time",
1224  "Europe/Kaliningrad"
1225  },
1226  {
1227  /* (UTC+03:00) Moscow, St. Petersburg */
1228  "Russia TZ 2 Standard Time", "Russia TZ 2 Daylight Time",
1229  "Europe/Moscow"
1230  },
1231  {
1232  /* (UTC+04:00) Izhevsk, Samara */
1233  "Russia TZ 3 Standard Time", "Russia TZ 3 Daylight Time",
1234  "Europe/Samara"
1235  },
1236  {
1237  /* (UTC+05:00) Ekaterinburg */
1238  "Russia TZ 4 Standard Time", "Russia TZ 4 Daylight Time",
1239  "Asia/Yekaterinburg"
1240  },
1241  {
1242  /* (UTC+06:00) Novosibirsk (RTZ 5) */
1243  "Russia TZ 5 Standard Time", "Russia TZ 5 Daylight Time",
1244  "Asia/Novosibirsk"
1245  },
1246  {
1247  /* (UTC+07:00) Krasnoyarsk */
1248  "Russia TZ 6 Standard Time", "Russia TZ 6 Daylight Time",
1249  "Asia/Krasnoyarsk"
1250  },
1251  {
1252  /* (UTC+08:00) Irkutsk */
1253  "Russia TZ 7 Standard Time", "Russia TZ 7 Daylight Time",
1254  "Asia/Irkutsk"
1255  },
1256  {
1257  /* (UTC+09:00) Yakutsk */
1258  "Russia TZ 8 Standard Time", "Russia TZ 8 Daylight Time",
1259  "Asia/Yakutsk"
1260  },
1261  {
1262  /* (UTC+10:00) Vladivostok */
1263  "Russia TZ 9 Standard Time", "Russia TZ 9 Daylight Time",
1264  "Asia/Vladivostok"
1265  },
1266  {
1267  /* (UTC+11:00) Chokurdakh */
1268  "Russia TZ 10 Standard Time", "Russia TZ 10 Daylight Time",
1269  "Asia/Magadan"
1270  },
1271  {
1272  /* (UTC+12:00) Anadyr, Petropavlovsk-Kamchatsky */
1273  "Russia TZ 11 Standard Time", "Russia TZ 11 Daylight Time",
1274  "Asia/Anadyr"
1275  },
1276  {
1277  /* (UTC+03:00) Moscow, St. Petersburg, Volgograd */
1278  "Russian Standard Time", "Russian Daylight Time",
1279  "Europe/Moscow"
1280  },
1281  {
1282  /* (UTC-03:00) Cayenne, Fortaleza */
1283  "SA Eastern Standard Time", "SA Eastern Daylight Time",
1284  "America/Buenos_Aires"
1285  },
1286  {
1287  /* (UTC-05:00) Bogota, Lima, Quito, Rio Branco */
1288  "SA Pacific Standard Time", "SA Pacific Daylight Time",
1289  "America/Bogota"
1290  },
1291  {
1292  /* (UTC-04:00) Georgetown, La Paz, Manaus, San Juan */
1293  "SA Western Standard Time", "SA Western Daylight Time",
1294  "America/Caracas"
1295  },
1296  {
1297  /* (UTC-03:00) Saint Pierre and Miquelon */
1298  "Saint Pierre Standard Time", "Saint Pierre Daylight Time",
1299  "America/Miquelon"
1300  },
1301  {
1302  /* (UTC+13:00) Samoa */
1303  "Samoa Standard Time", "Samoa Daylight Time",
1304  "Pacific/Samoa"
1305  },
1306  {
1307  /* (UTC+00:00) Sao Tome */
1308  "Sao Tome Standard Time", "Sao Tome Daylight Time",
1309  "Africa/Sao_Tome"
1310  },
1311  {
1312  /* (UTC+04:00) Saratov */
1313  "Saratov Standard Time", "Saratov Daylight Time",
1314  "Europe/Saratov"
1315  },
1316  {
1317  /* (UTC+07:00) Bangkok, Hanoi, Jakarta */
1318  "SE Asia Standard Time", "SE Asia Daylight Time",
1319  "Asia/Bangkok"
1320  },
1321  {
1322  /* (UTC+08:00) Kuala Lumpur, Singapore */
1323  "Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
1324  "Asia/Kuala_Lumpur"
1325  },
1326  {
1327  /* (UTC+11:00) Sakhalin */
1328  "Sakhalin Standard Time", "Sakhalin Daylight Time",
1329  "Asia/Sakhalin"
1330  },
1331  {
1332  /* (UTC+02:00) Harare, Pretoria */
1333  "South Africa Standard Time", "South Africa Daylight Time",
1334  "Africa/Harare"
1335  },
1336  {
1337  /* (UTC+05:30) Sri Jayawardenepura */
1338  "Sri Lanka Standard Time", "Sri Lanka Daylight Time",
1339  "Asia/Colombo"
1340  },
1341  {
1342  /* (UTC+02:00) Khartoum */
1343  "Sudan Standard Time", "Sudan Daylight Time",
1344  "Africa/Khartoum"
1345  },
1346  {
1347  /* (UTC+02:00) Damascus */
1348  "Syria Standard Time", "Syria Daylight Time",
1349  "Asia/Damascus"
1350  },
1351  {
1352  /* (UTC+08:00) Taipei */
1353  "Taipei Standard Time", "Taipei Daylight Time",
1354  "Asia/Taipei"
1355  },
1356  {
1357  /* (UTC+10:00) Hobart */
1358  "Tasmania Standard Time", "Tasmania Daylight Time",
1359  "Australia/Hobart"
1360  },
1361  {
1362  /* (UTC-03:00) Araguaina */
1363  "Tocantins Standard Time", "Tocantins Daylight Time",
1364  "America/Araguaina"
1365  },
1366  {
1367  /* (UTC+09:00) Osaka, Sapporo, Tokyo */
1368  "Tokyo Standard Time", "Tokyo Daylight Time",
1369  "Asia/Tokyo"
1370  },
1371  {
1372  /* (UTC+13:00) Nuku'alofa */
1373  "Tonga Standard Time", "Tonga Daylight Time",
1374  "Pacific/Tongatapu"
1375  },
1376  {
1377  /* (UTC+07:00) Tomsk */
1378  "Tomsk Standard Time", "Tomsk Daylight Time",
1379  "Asia/Tomsk"
1380  },
1381  {
1382  /* (UTC+09:00) Chita */
1383  "Transbaikal Standard Time", "Transbaikal Daylight Time",
1384  "Asia/Chita"
1385  },
1386  {
1387  /* (UTC+03:00) Istanbul */
1388  "Turkey Standard Time", "Turkey Daylight Time",
1389  "Europe/Istanbul"
1390  },
1391  {
1392  /* (UTC-05:00) Turks and Caicos */
1393  "Turks and Caicos Standard Time", "Turks and Caicos Daylight Time",
1394  "America/Grand_Turk"
1395  },
1396  {
1397  /* (UTC+08:00) Ulaanbaatar */
1398  "Ulaanbaatar Standard Time", "Ulaanbaatar Daylight Time",
1399  "Asia/Ulaanbaatar",
1400  },
1401  {
1402  /* (UTC-05:00) Indiana (East) */
1403  "US Eastern Standard Time", "US Eastern Daylight Time",
1404  "US/Eastern"
1405  },
1406  {
1407  /* (UTC-07:00) Arizona */
1408  "US Mountain Standard Time", "US Mountain Daylight Time",
1409  "US/Arizona"
1410  },
1411  {
1412  /* (UTC) Coordinated Universal Time */
1413  "Coordinated Universal Time", "Coordinated Universal Time",
1414  "UTC"
1415  },
1416  {
1417  /* (UTC+12:00) Coordinated Universal Time+12 */
1418  "UTC+12", "UTC+12",
1419  "Etc/GMT+12"
1420  },
1421  {
1422  /* (UTC+13:00) Coordinated Universal Time+13 */
1423  "UTC+13", "UTC+13",
1424  "Etc/GMT+13"
1425  },
1426  {
1427  /* (UTC-02:00) Coordinated Universal Time-02 */
1428  "UTC-02", "UTC-02",
1429  "Etc/GMT-02"
1430  },
1431  {
1432  /* (UTC-08:00) Coordinated Universal Time-08 */
1433  "UTC-08", "UTC-08",
1434  "Etc/GMT-08"
1435  },
1436  {
1437  /* (UTC-09:00) Coordinated Universal Time-09 */
1438  "UTC-09", "UTC-09",
1439  "Etc/GMT-09"
1440  },
1441  {
1442  /* (UTC-11:00) Coordinated Universal Time-11 */
1443  "UTC-11", "UTC-11",
1444  "Etc/GMT-11"
1445  },
1446  {
1447  /* (UTC-04:00) Caracas */
1448  "Venezuela Standard Time", "Venezuela Daylight Time",
1449  "America/Caracas",
1450  },
1451  {
1452  /* (UTC+10:00) Vladivostok (RTZ 9) */
1453  "Vladivostok Standard Time", "Vladivostok Daylight Time",
1454  "Asia/Vladivostok"
1455  },
1456  {
1457  /* (UTC+04:00) Volgograd */
1458  "Volgograd Standard Time", "Volgograd Daylight Time",
1459  "Europe/Volgograd"
1460  },
1461  {
1462  /* (UTC+08:00) Perth */
1463  "W. Australia Standard Time", "W. Australia Daylight Time",
1464  "Australia/Perth"
1465  },
1466 #ifdef NOT_USED
1467  /* Could not find a match for this one (just a guess). Excluded for now. */
1468  {
1469  /* (UTC+01:00) West Central Africa */
1470  "W. Central Africa Standard Time", "W. Central Africa Daylight Time",
1471  "WAT"
1472  },
1473 #endif
1474  {
1475  /* (UTC+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna */
1476  "W. Europe Standard Time", "W. Europe Daylight Time",
1477  "CET"
1478  },
1479  {
1480  /* (UTC+07:00) Hovd */
1481  "W. Mongolia Standard Time", "W. Mongolia Daylight Time",
1482  "Asia/Hovd"
1483  },
1484  {
1485  /* (UTC+05:00) Ashgabat, Tashkent */
1486  "West Asia Standard Time", "West Asia Daylight Time",
1487  "Asia/Karachi"
1488  },
1489  {
1490  /* (UTC+02:00) Gaza, Hebron */
1491  "West Bank Gaza Standard Time", "West Bank Gaza Daylight Time",
1492  "Asia/Gaza"
1493  },
1494  {
1495  /* (UTC+10:00) Guam, Port Moresby */
1496  "West Pacific Standard Time", "West Pacific Daylight Time",
1497  "Pacific/Guam"
1498  },
1499  {
1500  /* (UTC+09:00) Yakutsk */
1501  "Yakutsk Standard Time", "Yakutsk Daylight Time",
1502  "Asia/Yakutsk"
1503  },
1504  {
1505  NULL, NULL, NULL
1506  }
1507 };
1508 
1509 static const char *
1511 {
1512  int i;
1513  char tzname[128];
1514  char localtzname[256];
1515  time_t t = time(NULL);
1516  struct tm *tm = localtime(&t);
1517  HKEY rootKey;
1518  int idx;
1519 
1520  if (!tm)
1521  {
1522 #ifdef DEBUG_IDENTIFY_TIMEZONE
1523  fprintf(stderr, "could not identify system time zone: localtime() failed\n");
1524 #endif
1525  return NULL; /* go to GMT */
1526  }
1527 
1528  memset(tzname, 0, sizeof(tzname));
1529  strftime(tzname, sizeof(tzname) - 1, "%Z", tm);
1530 
1531  for (i = 0; win32_tzmap[i].stdname != NULL; i++)
1532  {
1533  if (strcmp(tzname, win32_tzmap[i].stdname) == 0 ||
1534  strcmp(tzname, win32_tzmap[i].dstname) == 0)
1535  {
1536 #ifdef DEBUG_IDENTIFY_TIMEZONE
1537  fprintf(stderr, "TZ \"%s\" matches system time zone \"%s\"\n",
1538  win32_tzmap[i].pgtzname, tzname);
1539 #endif
1540  return win32_tzmap[i].pgtzname;
1541  }
1542  }
1543 
1544  /*
1545  * Localized Windows versions return localized names for the timezone.
1546  * Scan the registry to find the English name, and then try matching
1547  * against our table again.
1548  */
1549  memset(localtzname, 0, sizeof(localtzname));
1550  if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
1551  "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
1552  0,
1553  KEY_READ,
1554  &rootKey) != ERROR_SUCCESS)
1555  {
1556 #ifdef DEBUG_IDENTIFY_TIMEZONE
1557  fprintf(stderr, "could not open registry key to identify system time zone: error code %lu\n",
1558  GetLastError());
1559 #endif
1560  return NULL; /* go to GMT */
1561  }
1562 
1563  for (idx = 0;; idx++)
1564  {
1565  char keyname[256];
1566  char zonename[256];
1567  DWORD namesize;
1568  FILETIME lastwrite;
1569  HKEY key;
1570  LONG r;
1571 
1572  memset(keyname, 0, sizeof(keyname));
1573  namesize = sizeof(keyname);
1574  if ((r = RegEnumKeyEx(rootKey,
1575  idx,
1576  keyname,
1577  &namesize,
1578  NULL,
1579  NULL,
1580  NULL,
1581  &lastwrite)) != ERROR_SUCCESS)
1582  {
1583  if (r == ERROR_NO_MORE_ITEMS)
1584  break;
1585 #ifdef DEBUG_IDENTIFY_TIMEZONE
1586  fprintf(stderr, "could not enumerate registry subkeys to identify system time zone: %d\n",
1587  (int) r);
1588 #endif
1589  break;
1590  }
1591 
1592  if ((r = RegOpenKeyEx(rootKey, keyname, 0, KEY_READ, &key)) != ERROR_SUCCESS)
1593  {
1594 #ifdef DEBUG_IDENTIFY_TIMEZONE
1595  fprintf(stderr, "could not open registry subkey to identify system time zone: %d\n",
1596  (int) r);
1597 #endif
1598  break;
1599  }
1600 
1601  memset(zonename, 0, sizeof(zonename));
1602  namesize = sizeof(zonename);
1603  if ((r = RegQueryValueEx(key, "Std", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
1604  {
1605 #ifdef DEBUG_IDENTIFY_TIMEZONE
1606  fprintf(stderr, "could not query value for key \"std\" to identify system time zone \"%s\": %d\n",
1607  keyname, (int) r);
1608 #endif
1609  RegCloseKey(key);
1610  continue; /* Proceed to look at the next timezone */
1611  }
1612  if (strcmp(tzname, zonename) == 0)
1613  {
1614  /* Matched zone */
1615  strcpy(localtzname, keyname);
1616  RegCloseKey(key);
1617  break;
1618  }
1619  memset(zonename, 0, sizeof(zonename));
1620  namesize = sizeof(zonename);
1621  if ((r = RegQueryValueEx(key, "Dlt", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
1622  {
1623 #ifdef DEBUG_IDENTIFY_TIMEZONE
1624  fprintf(stderr, "could not query value for key \"dlt\" to identify system time zone \"%s\": %d\n",
1625  keyname, (int) r);
1626 #endif
1627  RegCloseKey(key);
1628  continue; /* Proceed to look at the next timezone */
1629  }
1630  if (strcmp(tzname, zonename) == 0)
1631  {
1632  /* Matched DST zone */
1633  strcpy(localtzname, keyname);
1634  RegCloseKey(key);
1635  break;
1636  }
1637 
1638  RegCloseKey(key);
1639  }
1640 
1641  RegCloseKey(rootKey);
1642 
1643  if (localtzname[0])
1644  {
1645  /* Found a localized name, so scan for that one too */
1646  for (i = 0; win32_tzmap[i].stdname != NULL; i++)
1647  {
1648  if (strcmp(localtzname, win32_tzmap[i].stdname) == 0 ||
1649  strcmp(localtzname, win32_tzmap[i].dstname) == 0)
1650  {
1651 #ifdef DEBUG_IDENTIFY_TIMEZONE
1652  fprintf(stderr, "TZ \"%s\" matches localized system time zone \"%s\" (\"%s\")\n",
1653  win32_tzmap[i].pgtzname, tzname, localtzname);
1654 #endif
1655  return win32_tzmap[i].pgtzname;
1656  }
1657  }
1658  }
1659 
1660 #ifdef DEBUG_IDENTIFY_TIMEZONE
1661  fprintf(stderr, "could not find a match for system time zone \"%s\"\n",
1662  tzname);
1663 #endif
1664  return NULL; /* go to GMT */
1665 }
1666 #endif /* WIN32 */
1667 
1668 
1669 /*
1670  * Return true if the given zone name is valid and is an "acceptable" zone.
1671  */
1672 static bool
1673 validate_zone(const char *tzname)
1674 {
1675  pg_tz *tz;
1676 
1677  if (!tzname || !tzname[0])
1678  return false;
1679 
1680  tz = pg_load_tz(tzname);
1681  if (!tz)
1682  return false;
1683 
1684  if (!pg_tz_acceptable(tz))
1685  return false;
1686 
1687  return true;
1688 }
1689 
1690 /*
1691  * Identify a suitable default timezone setting based on the environment.
1692  *
1693  * The installation share_path must be passed in, as that is the default
1694  * location for the timezone database directory.
1695  *
1696  * We first look to the TZ environment variable. If not found or not
1697  * recognized by our own code, we see if we can identify the timezone
1698  * from the behavior of the system timezone library. When all else fails,
1699  * return NULL, indicating that we should default to GMT.
1700  */
1701 const char *
1703 {
1704  const char *tzname;
1705 
1706  /* Initialize timezone directory path, if needed */
1707 #ifndef SYSTEMTZDIR
1708  snprintf(tzdirpath, sizeof(tzdirpath), "%s/timezone", share_path);
1709 #endif
1710 
1711  /* Check TZ environment variable */
1712  tzname = getenv("TZ");
1713  if (validate_zone(tzname))
1714  return tzname;
1715 
1716  /* Nope, so try to identify the system timezone */
1717  tzname = identify_system_timezone();
1718  if (validate_zone(tzname))
1719  return tzname;
1720 
1721  return NULL;
1722 }
#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:33
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:35
int tzload(const char *name, char *canonname, struct state *sp, bool doextend)
Definition: localtime.c:584
int tm_hour
Definition: pgtime.h:29
#define TIMEZONE_GLOBAL
Definition: port.h:246
#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:25
static pg_tz * pg_load_tz(const char *name)
Definition: findtimezone.c:91
#define fprintf
Definition: port.h:220
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:44
#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
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Definition: pgtime.h:30
int tm_mon
Definition: pgtime.h:31
#define readlink(path, buf, size)
Definition: win32_port.h:228
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:37
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:260
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:229
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
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Definition: localtime.c:1342
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Definition: encode.c:515
#define S_ISDIR(m)
Definition: win32_port.h:316
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Definition: pgtime.h:32
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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:34
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Definition: pgtime.h:27
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Definition: port.h:216
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Definition: pgtime.h:28
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Definition: win32_port.h:275
#define MAX_TEST_TIMES
Definition: findtimezone.c:156