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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) 1996-2020, 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 
199  return mktime(&tm);
200 }
201 
202 /*
203  * Does a system tm value match one we computed ourselves?
204  */
205 static bool
206 compare_tm(struct tm *s, struct pg_tm *p)
207 {
208  if (s->tm_sec != p->tm_sec ||
209  s->tm_min != p->tm_min ||
210  s->tm_hour != p->tm_hour ||
211  s->tm_mday != p->tm_mday ||
212  s->tm_mon != p->tm_mon ||
213  s->tm_year != p->tm_year ||
214  s->tm_wday != p->tm_wday ||
215  s->tm_yday != p->tm_yday ||
216  s->tm_isdst != p->tm_isdst)
217  return false;
218  return true;
219 }
220 
221 /*
222  * See how well a specific timezone setting matches the system behavior
223  *
224  * We score a timezone setting according to the number of test times it
225  * matches. (The test times are ordered later-to-earlier, but this routine
226  * doesn't actually know that; it just scans until the first non-match.)
227  *
228  * We return -1 for a completely unusable setting; this is worse than the
229  * score of zero for a setting that works but matches not even the first
230  * test time.
231  */
232 static int
233 score_timezone(const char *tzname, struct tztry *tt)
234 {
235  int i;
236  pg_time_t pgtt;
237  struct tm *systm;
238  struct pg_tm *pgtm;
239  char cbuf[TZ_STRLEN_MAX + 1];
240  pg_tz *tz;
241 
242  /* Load timezone definition */
243  tz = pg_load_tz(tzname);
244  if (!tz)
245  return -1; /* unrecognized zone name */
246 
247  /* Reject if leap seconds involved */
248  if (!pg_tz_acceptable(tz))
249  {
250 #ifdef DEBUG_IDENTIFY_TIMEZONE
251  fprintf(stderr, "Reject TZ \"%s\": uses leap seconds\n", tzname);
252 #endif
253  return -1;
254  }
255 
256  /* Check for match at all the test times */
257  for (i = 0; i < tt->n_test_times; i++)
258  {
259  pgtt = (pg_time_t) (tt->test_times[i]);
260  pgtm = pg_localtime(&pgtt, tz);
261  if (!pgtm)
262  return -1; /* probably shouldn't happen */
263  systm = localtime(&(tt->test_times[i]));
264  if (!systm)
265  {
266 #ifdef DEBUG_IDENTIFY_TIMEZONE
267  fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s, system had no data\n",
268  tzname, i, (long) pgtt,
269  pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
270  pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
271  pgtm->tm_isdst ? "dst" : "std");
272 #endif
273  return i;
274  }
275  if (!compare_tm(systm, pgtm))
276  {
277 #ifdef DEBUG_IDENTIFY_TIMEZONE
278  fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s versus %04d-%02d-%02d %02d:%02d:%02d %s\n",
279  tzname, i, (long) pgtt,
280  pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
281  pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
282  pgtm->tm_isdst ? "dst" : "std",
283  systm->tm_year + 1900, systm->tm_mon + 1, systm->tm_mday,
284  systm->tm_hour, systm->tm_min, systm->tm_sec,
285  systm->tm_isdst ? "dst" : "std");
286 #endif
287  return i;
288  }
289  if (systm->tm_isdst >= 0)
290  {
291  /* Check match of zone names, too */
292  if (pgtm->tm_zone == NULL)
293  return -1; /* probably shouldn't happen */
294  memset(cbuf, 0, sizeof(cbuf));
295  strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm); /* zone abbr */
296  if (strcmp(cbuf, pgtm->tm_zone) != 0)
297  {
298 #ifdef DEBUG_IDENTIFY_TIMEZONE
299  fprintf(stderr, "TZ \"%s\" scores %d: at %ld \"%s\" versus \"%s\"\n",
300  tzname, i, (long) pgtt,
301  pgtm->tm_zone, cbuf);
302 #endif
303  return i;
304  }
305  }
306  }
307 
308 #ifdef DEBUG_IDENTIFY_TIMEZONE
309  fprintf(stderr, "TZ \"%s\" gets max score %d\n", tzname, i);
310 #endif
311 
312  return i;
313 }
314 
315 /*
316  * Test whether given zone name is a perfect match to localtime() behavior
317  */
318 static bool
319 perfect_timezone_match(const char *tzname, struct tztry *tt)
320 {
321  return (score_timezone(tzname, tt) == tt->n_test_times);
322 }
323 
324 
325 /*
326  * Try to identify a timezone name (in our terminology) that best matches the
327  * observed behavior of the system localtime() function.
328  */
329 static const char *
331 {
332  static char resultbuf[TZ_STRLEN_MAX + 1];
333  time_t tnow;
334  time_t t;
335  struct tztry tt;
336  struct tm *tm;
337  int thisyear;
338  int bestscore;
339  char tmptzdir[MAXPGPATH];
340  int std_ofs;
341  char std_zone_name[TZ_STRLEN_MAX + 1],
342  dst_zone_name[TZ_STRLEN_MAX + 1];
343  char cbuf[TZ_STRLEN_MAX + 1];
344 
345  /* Initialize OS timezone library */
346  tzset();
347 
348  /*
349  * Set up the list of dates to be probed to see how well our timezone
350  * matches the system zone. We first probe January and July of the
351  * current year; this serves to quickly eliminate the vast majority of the
352  * TZ database entries. If those dates match, we probe every week for 100
353  * years backwards from the current July. (Weekly resolution is good
354  * enough to identify DST transition rules, since everybody switches on
355  * Sundays.) This is sufficient to cover most of the Unix time_t range,
356  * and we don't want to look further than that since many systems won't
357  * have sane TZ behavior further back anyway. The further back the zone
358  * matches, the better we score it. This may seem like a rather random
359  * way of doing things, but experience has shown that system-supplied
360  * timezone definitions are likely to have DST behavior that is right for
361  * the recent past and not so accurate further back. Scoring in this way
362  * allows us to recognize zones that have some commonality with the IANA
363  * database, without insisting on exact match. (Note: we probe Thursdays,
364  * not Sundays, to avoid triggering DST-transition bugs in localtime
365  * itself.)
366  */
367  tnow = time(NULL);
368  tm = localtime(&tnow);
369  if (!tm)
370  return NULL; /* give up if localtime is broken... */
371  thisyear = tm->tm_year + 1900;
372 
373  t = build_time_t(thisyear, 1, 15);
374 
375  /*
376  * Round back to GMT midnight Thursday. This depends on the knowledge
377  * that the time_t origin is Thu Jan 01 1970. (With a different origin
378  * we'd be probing some other day of the week, but it wouldn't matter
379  * anyway unless localtime() had DST-transition bugs.)
380  */
381  t -= (t % T_WEEK);
382 
383  tt.n_test_times = 0;
384  tt.test_times[tt.n_test_times++] = t;
385 
386  t = build_time_t(thisyear, 7, 15);
387  t -= (t % T_WEEK);
388 
389  tt.test_times[tt.n_test_times++] = t;
390 
391  while (tt.n_test_times < MAX_TEST_TIMES)
392  {
393  t -= T_WEEK;
394  tt.test_times[tt.n_test_times++] = t;
395  }
396 
397  /*
398  * Try to avoid the brute-force search by seeing if we can recognize the
399  * system's timezone setting directly.
400  *
401  * Currently we just check /etc/localtime; there are other conventions for
402  * this, but that seems to be the only one used on enough platforms to be
403  * worth troubling over.
404  */
405  if (check_system_link_file("/etc/localtime", &tt, resultbuf))
406  return resultbuf;
407 
408  /* No luck, so search for the best-matching timezone file */
409  strlcpy(tmptzdir, pg_TZDIR(), sizeof(tmptzdir));
410  bestscore = -1;
411  resultbuf[0] = '\0';
412  scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1,
413  &tt,
414  &bestscore, resultbuf);
415  if (bestscore > 0)
416  {
417  /* Ignore IANA's rather silly "Factory" zone; use GMT instead */
418  if (strcmp(resultbuf, "Factory") == 0)
419  return NULL;
420  return resultbuf;
421  }
422 
423  /*
424  * Couldn't find a match in the database, so next we try constructed zone
425  * names (like "PST8PDT").
426  *
427  * First we need to determine the names of the local standard and daylight
428  * zones. The idea here is to scan forward from today until we have seen
429  * both zones, if both are in use.
430  */
431  memset(std_zone_name, 0, sizeof(std_zone_name));
432  memset(dst_zone_name, 0, sizeof(dst_zone_name));
433  std_ofs = 0;
434 
435  tnow = time(NULL);
436 
437  /*
438  * Round back to a GMT midnight so results don't depend on local time of
439  * day
440  */
441  tnow -= (tnow % T_DAY);
442 
443  /*
444  * We have to look a little further ahead than one year, in case today is
445  * just past a DST boundary that falls earlier in the year than the next
446  * similar boundary. Arbitrarily scan up to 14 months.
447  */
448  for (t = tnow; t <= tnow + T_MONTH * 14; t += T_MONTH)
449  {
450  tm = localtime(&t);
451  if (!tm)
452  continue;
453  if (tm->tm_isdst < 0)
454  continue;
455  if (tm->tm_isdst == 0 && std_zone_name[0] == '\0')
456  {
457  /* found STD zone */
458  memset(cbuf, 0, sizeof(cbuf));
459  strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
460  strcpy(std_zone_name, cbuf);
461  std_ofs = get_timezone_offset(tm);
462  }
463  if (tm->tm_isdst > 0 && dst_zone_name[0] == '\0')
464  {
465  /* found DST zone */
466  memset(cbuf, 0, sizeof(cbuf));
467  strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
468  strcpy(dst_zone_name, cbuf);
469  }
470  /* Done if found both */
471  if (std_zone_name[0] && dst_zone_name[0])
472  break;
473  }
474 
475  /* We should have found a STD zone name by now... */
476  if (std_zone_name[0] == '\0')
477  {
478 #ifdef DEBUG_IDENTIFY_TIMEZONE
479  fprintf(stderr, "could not determine system time zone\n");
480 #endif
481  return NULL; /* go to GMT */
482  }
483 
484  /* If we found DST then try STD<ofs>DST */
485  if (dst_zone_name[0] != '\0')
486  {
487  snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
488  std_zone_name, -std_ofs / 3600, dst_zone_name);
489  if (score_timezone(resultbuf, &tt) > 0)
490  return resultbuf;
491  }
492 
493  /* Try just the STD timezone (works for GMT at least) */
494  strcpy(resultbuf, std_zone_name);
495  if (score_timezone(resultbuf, &tt) > 0)
496  return resultbuf;
497 
498  /* Try STD<ofs> */
499  snprintf(resultbuf, sizeof(resultbuf), "%s%d",
500  std_zone_name, -std_ofs / 3600);
501  if (score_timezone(resultbuf, &tt) > 0)
502  return resultbuf;
503 
504  /*
505  * Did not find the timezone. Fallback to use a GMT zone. Note that the
506  * IANA timezone database names the GMT-offset zones in POSIX style: plus
507  * is west of Greenwich. It's unfortunate that this is opposite of SQL
508  * conventions. Should we therefore change the names? Probably not...
509  */
510  snprintf(resultbuf, sizeof(resultbuf), "Etc/GMT%s%d",
511  (-std_ofs > 0) ? "+" : "", -std_ofs / 3600);
512 
513 #ifdef DEBUG_IDENTIFY_TIMEZONE
514  fprintf(stderr, "could not recognize system time zone, using \"%s\"\n",
515  resultbuf);
516 #endif
517  return resultbuf;
518 }
519 
520 /*
521  * Examine a system-provided symlink file to see if it tells us the timezone.
522  *
523  * Unfortunately, there is little standardization of how the system default
524  * timezone is determined in the absence of a TZ environment setting.
525  * But a common strategy is to create a symlink at a well-known place.
526  * If "linkname" identifies a readable symlink, and the tail of its contents
527  * matches a zone name we know, and the actual behavior of localtime() agrees
528  * with what we think that zone means, then we may use that zone name.
529  *
530  * We insist on a perfect behavioral match, which might not happen if the
531  * system has a different IANA database version than we do; but in that case
532  * it seems best to fall back to the brute-force search.
533  *
534  * linkname is the symlink file location to probe.
535  *
536  * tt tells about the system timezone behavior we need to match.
537  *
538  * If we successfully identify a zone name, store it in *bestzonename and
539  * return true; else return false. bestzonename must be a buffer of length
540  * TZ_STRLEN_MAX + 1.
541  */
542 static bool
543 check_system_link_file(const char *linkname, struct tztry *tt,
544  char *bestzonename)
545 {
546 #ifdef HAVE_READLINK
547  char link_target[MAXPGPATH];
548  int len;
549  const char *cur_name;
550 
551  /*
552  * Try to read the symlink. If not there, not a symlink, etc etc, just
553  * quietly fail; the precise reason needn't concern us.
554  */
555  len = readlink(linkname, link_target, sizeof(link_target));
556  if (len < 0 || len >= sizeof(link_target))
557  return false;
558  link_target[len] = '\0';
559 
560 #ifdef DEBUG_IDENTIFY_TIMEZONE
561  fprintf(stderr, "symbolic link \"%s\" contains \"%s\"\n",
562  linkname, link_target);
563 #endif
564 
565  /*
566  * The symlink is probably of the form "/path/to/zones/zone/name", or
567  * possibly it is a relative path. Nobody puts their zone DB directly in
568  * the root directory, so we can definitely skip the first component; but
569  * after that it's trial-and-error to identify which path component begins
570  * the zone name.
571  */
572  cur_name = link_target;
573  while (*cur_name)
574  {
575  /* Advance to next segment of path */
576  cur_name = strchr(cur_name + 1, '/');
577  if (cur_name == NULL)
578  break;
579  /* If there are consecutive slashes, skip all, as the kernel would */
580  do
581  {
582  cur_name++;
583  } while (*cur_name == '/');
584 
585  /*
586  * Test remainder of path to see if it is a matching zone name.
587  * Relative paths might contain ".."; we needn't bother testing if the
588  * first component is that. Also defend against overlength names.
589  */
590  if (*cur_name && *cur_name != '.' &&
591  strlen(cur_name) <= TZ_STRLEN_MAX &&
592  perfect_timezone_match(cur_name, tt))
593  {
594  /* Success! */
595  strcpy(bestzonename, cur_name);
596  return true;
597  }
598  }
599 
600  /* Couldn't extract a matching zone name */
601  return false;
602 #else
603  /* No symlinks? Forget it */
604  return false;
605 #endif
606 }
607 
608 /*
609  * Given a timezone name, determine whether it should be preferred over other
610  * names which are equally good matches. The output is arbitrary but we will
611  * use 0 for "neutral" default preference; larger values are more preferred.
612  */
613 static int
614 zone_name_pref(const char *zonename)
615 {
616  /*
617  * Prefer UTC over alternatives such as UCT. Also prefer Etc/UTC over
618  * Etc/UCT; but UTC is preferred to Etc/UTC.
619  */
620  if (strcmp(zonename, "UTC") == 0)
621  return 50;
622  if (strcmp(zonename, "Etc/UTC") == 0)
623  return 40;
624 
625  /*
626  * We don't want to pick "localtime" or "posixrules", unless we can find
627  * no other name for the prevailing zone. Those aren't real zone names.
628  */
629  if (strcmp(zonename, "localtime") == 0 ||
630  strcmp(zonename, "posixrules") == 0)
631  return -50;
632 
633  return 0;
634 }
635 
636 /*
637  * Recursively scan the timezone database looking for the best match to
638  * the system timezone behavior.
639  *
640  * tzdir points to a buffer of size MAXPGPATH. On entry, it holds the
641  * pathname of a directory containing TZ files. We internally modify it
642  * to hold pathnames of sub-directories and files, but must restore it
643  * to its original contents before exit.
644  *
645  * tzdirsub points to the part of tzdir that represents the subfile name
646  * (ie, tzdir + the original directory name length, plus one for the
647  * first added '/').
648  *
649  * tt tells about the system timezone behavior we need to match.
650  *
651  * *bestscore and *bestzonename on entry hold the best score found so far
652  * and the name of the best zone. We overwrite them if we find a better
653  * score. bestzonename must be a buffer of length TZ_STRLEN_MAX + 1.
654  */
655 static void
656 scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt,
657  int *bestscore, char *bestzonename)
658 {
659  int tzdir_orig_len = strlen(tzdir);
660  char **names;
661  char **namep;
662 
663  names = pgfnames(tzdir);
664  if (!names)
665  return;
666 
667  for (namep = names; *namep; namep++)
668  {
669  char *name = *namep;
670  struct stat statbuf;
671 
672  /* Ignore . and .., plus any other "hidden" files */
673  if (name[0] == '.')
674  continue;
675 
676  snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
677  "/%s", name);
678 
679  if (stat(tzdir, &statbuf) != 0)
680  {
681 #ifdef DEBUG_IDENTIFY_TIMEZONE
682  fprintf(stderr, "could not stat \"%s\": %s\n",
683  tzdir, strerror(errno));
684 #endif
685  tzdir[tzdir_orig_len] = '\0';
686  continue;
687  }
688 
689  if (S_ISDIR(statbuf.st_mode))
690  {
691  /* Recurse into subdirectory */
692  scan_available_timezones(tzdir, tzdirsub, tt,
693  bestscore, bestzonename);
694  }
695  else
696  {
697  /* Load and test this file */
698  int score = score_timezone(tzdirsub, tt);
699 
700  if (score > *bestscore)
701  {
702  *bestscore = score;
703  strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
704  }
705  else if (score == *bestscore)
706  {
707  /* Consider how to break a tie */
708  int namepref = (zone_name_pref(tzdirsub) -
709  zone_name_pref(bestzonename));
710 
711  if (namepref > 0 ||
712  (namepref == 0 &&
713  (strlen(tzdirsub) < strlen(bestzonename) ||
714  (strlen(tzdirsub) == strlen(bestzonename) &&
715  strcmp(tzdirsub, bestzonename) < 0))))
716  strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
717  }
718  }
719 
720  /* Restore tzdir */
721  tzdir[tzdir_orig_len] = '\0';
722  }
723 
724  pgfnames_cleanup(names);
725 }
726 #else /* WIN32 */
727 
728 static const struct
729 {
730  const char *stdname; /* Windows name of standard timezone */
731  const char *dstname; /* Windows name of daylight timezone */
732  const char *pgtzname; /* Name of pgsql timezone to map to */
733 } win32_tzmap[] =
734 
735 {
736  /*
737  * This list was built from the contents of the registry at
738  * HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time
739  * Zones on Windows 7, Windows 10, and Windows Server 2019.
740  *
741  * The zones have been matched to IANA timezones by looking at the cities
742  * listed in the win32 display name (in the comment here) in most cases.
743  */
744  {
745  /* (UTC+04:30) Kabul */
746  "Afghanistan Standard Time", "Afghanistan Daylight Time",
747  "Asia/Kabul"
748  },
749  {
750  /* (UTC-09:00) Alaska */
751  "Alaskan Standard Time", "Alaskan Daylight Time",
752  "US/Alaska"
753  },
754  {
755  /* (UTC-10:00) Aleutian Islands */
756  "Aleutian Standard Time", "Aleutian Daylight Time",
757  "US/Aleutan"
758  },
759  {
760  /* (UTC+07:00) Barnaul, Gorno-Altaysk */
761  "Altai Standard Time", "Altai Daylight Time",
762  "Asia/Barnaul"
763  },
764  {
765  /* (UTC+03:00) Kuwait, Riyadh */
766  "Arab Standard Time", "Arab Daylight Time",
767  "Asia/Kuwait"
768  },
769  {
770  /* (UTC+04:00) Abu Dhabi, Muscat */
771  "Arabian Standard Time", "Arabian Daylight Time",
772  "Asia/Muscat"
773  },
774  {
775  /* (UTC+03:00) Baghdad */
776  "Arabic Standard Time", "Arabic Daylight Time",
777  "Asia/Baghdad"
778  },
779  {
780  /* (UTC-03:00) City of Buenos Aires */
781  "Argentina Standard Time", "Argentina Daylight Time",
782  "America/Buenos_Aires"
783  },
784  {
785  /* (UTC+04:00) Baku, Tbilisi, Yerevan */
786  "Armenian Standard Time", "Armenian Daylight Time",
787  "Asia/Yerevan"
788  },
789  {
790  /* (UTC+04:00) Astrakhan, Ulyanovsk */
791  "Astrakhan Standard Time", "Astrakhan Daylight Time",
792  "Europe/Astrakhan"
793  },
794  {
795  /* (UTC-04:00) Atlantic Time (Canada) */
796  "Atlantic Standard Time", "Atlantic Daylight Time",
797  "Canada/Atlantic"
798  },
799  {
800  /* (UTC+09:30) Darwin */
801  "AUS Central Standard Time", "AUS Central Daylight Time",
802  "Australia/Darwin"
803  },
804  {
805  /* (UTC+08:45) Eucla */
806  "Aus Central W. Standard Time", "Aus Central W. Daylight Time",
807  "Australia/Eucla"
808  },
809  {
810  /* (UTC+10:00) Canberra, Melbourne, Sydney */
811  "AUS Eastern Standard Time", "AUS Eastern Daylight Time",
812  "Australia/Canberra"
813  },
814  {
815  /* (UTC+04:00) Baku */
816  "Azerbaijan Standard Time", "Azerbaijan Daylight Time",
817  "Asia/Baku"
818  },
819  {
820  /* (UTC-01:00) Azores */
821  "Azores Standard Time", "Azores Daylight Time",
822  "Atlantic/Azores"
823  },
824  {
825  /* (UTC-03:00) Salvador */
826  "Bahia Standard Time", "Bahia Daylight Time",
827  "America/Salvador"
828  },
829  {
830  /* (UTC+06:00) Dhaka */
831  "Bangladesh Standard Time", "Bangladesh Daylight Time",
832  "Asia/Dhaka"
833  },
834  {
835  /* (UTC+11:00) Bougainville Island */
836  "Bougainville Standard Time", "Bougainville Daylight Time",
837  "Pacific/Bougainville"
838  },
839  {
840  /* (UTC+03:00) Minsk */
841  "Belarus Standard Time", "Belarus Daylight Time",
842  "Europe/Minsk"
843  },
844  {
845  /* (UTC-01:00) Cabo Verde Is. */
846  "Cabo Verde Standard Time", "Cabo Verde Daylight Time",
847  "Atlantic/Cape_Verde"
848  },
849  {
850  /* (UTC+12:45) Chatham Islands */
851  "Chatham Islands Standard Time", "Chatham Islands Daylight Time",
852  "Pacific/Chatham"
853  },
854  {
855  /* (UTC-06:00) Saskatchewan */
856  "Canada Central Standard Time", "Canada Central Daylight Time",
857  "Canada/Saskatchewan"
858  },
859  {
860  /* (UTC-01:00) Cape Verde Is. */
861  "Cape Verde Standard Time", "Cape Verde Daylight Time",
862  "Atlantic/Cape_Verde"
863  },
864  {
865  /* (UTC+04:00) Yerevan */
866  "Caucasus Standard Time", "Caucasus Daylight Time",
867  "Asia/Baku"
868  },
869  {
870  /* (UTC+09:30) Adelaide */
871  "Cen. Australia Standard Time", "Cen. Australia Daylight Time",
872  "Australia/Adelaide"
873  },
874  /* Central America (other than Mexico) generally does not observe DST */
875  {
876  /* (UTC-06:00) Central America */
877  "Central America Standard Time", "Central America Daylight Time",
878  "CST6"
879  },
880  {
881  /* (UTC+06:00) Astana */
882  "Central Asia Standard Time", "Central Asia Daylight Time",
883  "Asia/Dhaka"
884  },
885  {
886  /* (UTC-04:00) Cuiaba */
887  "Central Brazilian Standard Time", "Central Brazilian Daylight Time",
888  "America/Cuiaba"
889  },
890  {
891  /* (UTC+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague */
892  "Central Europe Standard Time", "Central Europe Daylight Time",
893  "Europe/Belgrade"
894  },
895  {
896  /* (UTC+01:00) Sarajevo, Skopje, Warsaw, Zagreb */
897  "Central European Standard Time", "Central European Daylight Time",
898  "Europe/Sarajevo"
899  },
900  {
901  /* (UTC+11:00) Solomon Is., New Caledonia */
902  "Central Pacific Standard Time", "Central Pacific Daylight Time",
903  "Pacific/Noumea"
904  },
905  {
906  /* (UTC-06:00) Central Time (US & Canada) */
907  "Central Standard Time", "Central Daylight Time",
908  "US/Central"
909  },
910  {
911  /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */
912  "Central Standard Time (Mexico)", "Central Daylight Time (Mexico)",
913  "America/Mexico_City"
914  },
915  {
916  /* (UTC+08:00) Beijing, Chongqing, Hong Kong, Urumqi */
917  "China Standard Time", "China Daylight Time",
918  "Asia/Hong_Kong"
919  },
920  {
921  /* (UTC-05:00) Havana */
922  "Cuba Standard Time", "Cuba Daylight Time",
923  "America/Havana"
924  },
925  {
926  /* (UTC-12:00) International Date Line West */
927  "Dateline Standard Time", "Dateline Daylight Time",
928  "Etc/UTC+12"
929  },
930  {
931  /* (UTC+03:00) Nairobi */
932  "E. Africa Standard Time", "E. Africa Daylight Time",
933  "Africa/Nairobi"
934  },
935  {
936  /* (UTC+10:00) Brisbane */
937  "E. Australia Standard Time", "E. Australia Daylight Time",
938  "Australia/Brisbane"
939  },
940  {
941  /* (UTC+02:00) Chisinau */
942  "E. Europe Standard Time", "E. Europe Daylight Time",
943  "Europe/Bucharest"
944  },
945  {
946  /* (UTC-03:00) Brasilia */
947  "E. South America Standard Time", "E. South America Daylight Time",
948  "America/Araguaina"
949  },
950  {
951  /* (UTC-05:00) Eastern Time (US & Canada) */
952  "Eastern Standard Time", "Eastern Daylight Time",
953  "US/Eastern"
954  },
955  {
956  /* (UTC-05:00) Chetumal */
957  "Eastern Standard Time (Mexico)", "Eastern Daylight Time (Mexico)",
958  "America/Mexico_City"
959  },
960  {
961  /* (UTC-06:00) Easter Island */
962  "Easter Island Standard Time", "Easter Island Daylight Time",
963  "Pacific/Easter"
964  },
965  {
966  /* (UTC+02:00) Cairo */
967  "Egypt Standard Time", "Egypt Daylight Time",
968  "Africa/Cairo"
969  },
970  {
971  /* (UTC+05:00) Ekaterinburg */
972  "Ekaterinburg Standard Time (RTZ 4)", "Ekaterinburg Daylight Time",
973  "Asia/Yekaterinburg"
974  },
975  {
976  /* (UTC+12:00) Fiji */
977  "Fiji Standard Time", "Fiji Daylight Time",
978  "Pacific/Fiji"
979  },
980  {
981  /* (UTC+02:00) Helsinki, Kyiv, Riga, Sofia, Tallinn, Vilnius */
982  "FLE Standard Time", "FLE Daylight Time",
983  "Europe/Helsinki"
984  },
985  {
986  /* (UTC+04:00) Tbilisi */
987  "Georgian Standard Time", "Georgian Daylight Time",
988  "Asia/Tbilisi"
989  },
990  {
991  /* (UTC+00:00) Dublin, Edinburgh, Lisbon, London */
992  "GMT Standard Time", "GMT Daylight Time",
993  "Europe/London"
994  },
995  {
996  /* (UTC-03:00) Greenland */
997  "Greenland Standard Time", "Greenland Daylight Time",
998  "America/Godthab"
999  },
1000  {
1001  /* (UTC+00:00) Monrovia, Reykjavik */
1002  "Greenwich Standard Time", "Greenwich Daylight Time",
1003  "Africa/Casablanca"
1004  },
1005  {
1006  /* (UTC+02:00) Athens, Bucharest */
1007  "GTB Standard Time", "GTB Daylight Time",
1008  "Europe/Athens"
1009  },
1010  {
1011  /* (UTC-05:00) Haiti */
1012  "Haiti Standard Time", "Haiti Daylight Time",
1013  "US/Eastern"
1014  },
1015  {
1016  /* (UTC-10:00) Hawaii */
1017  "Hawaiian Standard Time", "Hawaiian Daylight Time",
1018  "US/Hawaii"
1019  },
1020  {
1021  /* (UTC+05:30) Chennai, Kolkata, Mumbai, New Delhi */
1022  "India Standard Time", "India Daylight Time",
1023  "Asia/Calcutta"
1024  },
1025  {
1026  /* (UTC+03:30) Tehran */
1027  "Iran Standard Time", "Iran Daylight Time",
1028  "Asia/Tehran"
1029  },
1030  {
1031  /* (UTC+02:00) Jerusalem */
1032  "Jerusalem Standard Time", "Jerusalem Daylight Time",
1033  "Asia/Jerusalem"
1034  },
1035  {
1036  /* (UTC+02:00) Amman */
1037  "Jordan Standard Time", "Jordan Daylight Time",
1038  "Asia/Amman"
1039  },
1040  {
1041  /* (UTC+12:00) Petropavlovsk-Kamchatsky - Old */
1042  "Kamchatka Standard Time", "Kamchatka Daylight Time",
1043  "Asia/Kamchatka"
1044  },
1045  {
1046  /* (UTC+09:00) Seoul */
1047  "Korea Standard Time", "Korea Daylight Time",
1048  "Asia/Seoul"
1049  },
1050  {
1051  /* (UTC+02:00) Tripoli */
1052  "Libya Standard Time", "Libya Daylight Time",
1053  "Africa/Tripoli"
1054  },
1055  {
1056  /* (UTC+14:00) Kiritimati Island */
1057  "Line Islands Standard Time", "Line Islands Daylight Time",
1058  "Pacific/Kiritimati"
1059  },
1060  {
1061  /* (UTC+10:30) Lord Howe Island */
1062  "Lord Howe Standard Time", "Lord Howe Daylight Time",
1063  "Australia/Lord_Howe"
1064  },
1065  {
1066  /* (UTC+11:00) Magadan */
1067  "Magadan Standard Time", "Magadan Daylight Time",
1068  "Asia/Magadan"
1069  },
1070  {
1071  /* (UTC-03:00) Punta Arenas */
1072  "Magallanes Standard Time", "Magallanes Daylight Time",
1073  "America/Punta_Arenas"
1074  },
1075  {
1076  /* (UTC-09:30) Marquesas Islands */
1077  "Marquesas Standard Time", "Marquesas Daylight Time",
1078  "Pacific/Marquesas"
1079  },
1080  {
1081  /* (UTC+04:00) Port Louis */
1082  "Mauritius Standard Time", "Mauritius Daylight Time",
1083  "Indian/Mauritius"
1084  },
1085  {
1086  /* (UTC-06:00) Guadalajara, Mexico City, Monterrey */
1087  "Mexico Standard Time", "Mexico Daylight Time",
1088  "America/Mexico_City"
1089  },
1090  {
1091  /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
1092  "Mexico Standard Time 2", "Mexico Daylight Time 2",
1093  "America/Chihuahua"
1094  },
1095  {
1096  /* (UTC-02:00) Mid-Atlantic - Old */
1097  "Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
1098  "Atlantic/South_Georgia"
1099  },
1100  {
1101  /* (UTC+02:00) Beirut */
1102  "Middle East Standard Time", "Middle East Daylight Time",
1103  "Asia/Beirut"
1104  },
1105  {
1106  /* (UTC-03:00) Montevideo */
1107  "Montevideo Standard Time", "Montevideo Daylight Time",
1108  "America/Montevideo"
1109  },
1110  {
1111  /* (UTC+01:00) Casablanca */
1112  "Morocco Standard Time", "Morocco Daylight Time",
1113  "Africa/Casablanca"
1114  },
1115  {
1116  /* (UTC-07:00) Mountain Time (US & Canada) */
1117  "Mountain Standard Time", "Mountain Daylight Time",
1118  "US/Mountain"
1119  },
1120  {
1121  /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
1122  "Mountain Standard Time (Mexico)", "Mountain Daylight Time (Mexico)",
1123  "America/Chihuahua"
1124  },
1125  {
1126  /* (UTC+06:30) Yangon (Rangoon) */
1127  "Myanmar Standard Time", "Myanmar Daylight Time",
1128  "Asia/Rangoon"
1129  },
1130  {
1131  /* (UTC+06:00) Novosibirsk (RTZ 5) */
1132  "N. Central Asia Standard Time", "N. Central Asia Daylight Time",
1133  "Asia/Novosibirsk"
1134  },
1135  {
1136  /* (UTC+02:00) Windhoek */
1137  "Namibia Standard Time", "Namibia Daylight Time",
1138  "Africa/Windhoek"
1139  },
1140  {
1141  /* (UTC+05:45) Kathmandu */
1142  "Nepal Standard Time", "Nepal Daylight Time",
1143  "Asia/Katmandu"
1144  },
1145  {
1146  /* (UTC+12:00) Auckland, Wellington */
1147  "New Zealand Standard Time", "New Zealand Daylight Time",
1148  "Pacific/Auckland"
1149  },
1150  {
1151  /* (UTC-03:30) Newfoundland */
1152  "Newfoundland Standard Time", "Newfoundland Daylight Time",
1153  "Canada/Newfoundland"
1154  },
1155  {
1156  /* (UTC+11:00) Norfolk Island */
1157  "Norfolk Standard Time", "Norfolk Daylight Time",
1158  "Pacific/Norfolk"
1159  },
1160  {
1161  /* (UTC+08:00) Irkutsk, Ulaan Bataar */
1162  "North Asia East Standard Time", "North Asia East Daylight Time",
1163  "Asia/Irkutsk"
1164  },
1165  {
1166  /* (UTC+07:00) Krasnoyarsk */
1167  "North Asia Standard Time", "North Asia Daylight Time",
1168  "Asia/Krasnoyarsk"
1169  },
1170  {
1171  /* (UTC+09:00) Pyongyang */
1172  "North Korea Standard Time", "North Korea Daylight Time",
1173  "Asia/Pyongyang"
1174  },
1175  {
1176  /* (UTC+07:00) Novosibirsk */
1177  "Novosibirsk Standard Time", "Novosibirsk Daylight Time",
1178  "Asia/Novosibirsk"
1179  },
1180  {
1181  /* (UTC+06:00) Omsk */
1182  "Omsk Standard Time", "Omsk Daylight Time",
1183  "Asia/Omsk"
1184  },
1185  {
1186  /* (UTC-04:00) Santiago */
1187  "Pacific SA Standard Time", "Pacific SA Daylight Time",
1188  "America/Santiago"
1189  },
1190  {
1191  /* (UTC-08:00) Pacific Time (US & Canada) */
1192  "Pacific Standard Time", "Pacific Daylight Time",
1193  "US/Pacific"
1194  },
1195  {
1196  /* (UTC-08:00) Baja California */
1197  "Pacific Standard Time (Mexico)", "Pacific Daylight Time (Mexico)",
1198  "America/Tijuana"
1199  },
1200  {
1201  /* (UTC+05:00) Islamabad, Karachi */
1202  "Pakistan Standard Time", "Pakistan Daylight Time",
1203  "Asia/Karachi"
1204  },
1205  {
1206  /* (UTC-04:00) Asuncion */
1207  "Paraguay Standard Time", "Paraguay Daylight Time",
1208  "America/Asuncion"
1209  },
1210  {
1211  /* (UTC+05:00) Qyzylorda */
1212  "Qyzylorda Standard Time", "Qyzylorda Daylight Time",
1213  "Asia/Qyzylorda"
1214  },
1215  {
1216  /* (UTC+01:00) Brussels, Copenhagen, Madrid, Paris */
1217  "Romance Standard Time", "Romance Daylight Time",
1218  "Europe/Brussels"
1219  },
1220  {
1221  /* (UTC+02:00) Kaliningrad */
1222  "Russia TZ 1 Standard Time", "Russia TZ 1 Daylight Time",
1223  "Europe/Kaliningrad"
1224  },
1225  {
1226  /* (UTC+03:00) Moscow, St. Petersburg */
1227  "Russia TZ 2 Standard Time", "Russia TZ 2 Daylight Time",
1228  "Europe/Moscow"
1229  },
1230  {
1231  /* (UTC+04:00) Izhevsk, Samara */
1232  "Russia TZ 3 Standard Time", "Russia TZ 3 Daylight Time",
1233  "Europe/Samara"
1234  },
1235  {
1236  /* (UTC+05:00) Ekaterinburg */
1237  "Russia TZ 4 Standard Time", "Russia TZ 4 Daylight Time",
1238  "Asia/Yekaterinburg"
1239  },
1240  {
1241  /* (UTC+06:00) Novosibirsk (RTZ 5) */
1242  "Russia TZ 5 Standard Time", "Russia TZ 5 Daylight Time",
1243  "Asia/Novosibirsk"
1244  },
1245  {
1246  /* (UTC+07:00) Krasnoyarsk */
1247  "Russia TZ 6 Standard Time", "Russia TZ 6 Daylight Time",
1248  "Asia/Krasnoyarsk"
1249  },
1250  {
1251  /* (UTC+08:00) Irkutsk */
1252  "Russia TZ 7 Standard Time", "Russia TZ 7 Daylight Time",
1253  "Asia/Irkutsk"
1254  },
1255  {
1256  /* (UTC+09:00) Yakutsk */
1257  "Russia TZ 8 Standard Time", "Russia TZ 8 Daylight Time",
1258  "Asia/Yakutsk"
1259  },
1260  {
1261  /* (UTC+10:00) Vladivostok */
1262  "Russia TZ 9 Standard Time", "Russia TZ 9 Daylight Time",
1263  "Asia/Vladivostok"
1264  },
1265  {
1266  /* (UTC+11:00) Chokurdakh */
1267  "Russia TZ 10 Standard Time", "Russia TZ 10 Daylight Time",
1268  "Asia/Magadan"
1269  },
1270  {
1271  /* (UTC+12:00) Anadyr, Petropavlovsk-Kamchatsky */
1272  "Russia TZ 11 Standard Time", "Russia TZ 11 Daylight Time",
1273  "Asia/Anadyr"
1274  },
1275  {
1276  /* (UTC+03:00) Moscow, St. Petersburg, Volgograd */
1277  "Russian Standard Time", "Russian Daylight Time",
1278  "Europe/Moscow"
1279  },
1280  {
1281  /* (UTC-03:00) Cayenne, Fortaleza */
1282  "SA Eastern Standard Time", "SA Eastern Daylight Time",
1283  "America/Buenos_Aires"
1284  },
1285  {
1286  /* (UTC-05:00) Bogota, Lima, Quito, Rio Branco */
1287  "SA Pacific Standard Time", "SA Pacific Daylight Time",
1288  "America/Bogota"
1289  },
1290  {
1291  /* (UTC-04:00) Georgetown, La Paz, Manaus, San Juan */
1292  "SA Western Standard Time", "SA Western Daylight Time",
1293  "America/Caracas"
1294  },
1295  {
1296  /* (UTC-03:00) Saint Pierre and Miquelon */
1297  "Saint Pierre Standard Time", "Saint Pierre Daylight Time",
1298  "America/Miquelon"
1299  },
1300  {
1301  /* (UTC+13:00) Samoa */
1302  "Samoa Standard Time", "Samoa Daylight Time",
1303  "Pacific/Samoa"
1304  },
1305  {
1306  /* (UTC+00:00) Sao Tome */
1307  "Sao Tome Standard Time", "Sao Tome Daylight Time",
1308  "Africa/Sao_Tome"
1309  },
1310  {
1311  /* (UTC+04:00) Saratov */
1312  "Saratov Standard Time", "Saratov Daylight Time",
1313  "Europe/Saratov"
1314  },
1315  {
1316  /* (UTC+07:00) Bangkok, Hanoi, Jakarta */
1317  "SE Asia Standard Time", "SE Asia Daylight Time",
1318  "Asia/Bangkok"
1319  },
1320  {
1321  /* (UTC+08:00) Kuala Lumpur, Singapore */
1322  "Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
1323  "Asia/Kuala_Lumpur"
1324  },
1325  {
1326  /* (UTC+11:00) Sakhalin */
1327  "Sakhalin Standard Time", "Sakhalin Daylight Time",
1328  "Asia/Sakhalin"
1329  },
1330  {
1331  /* (UTC+02:00) Harare, Pretoria */
1332  "South Africa Standard Time", "South Africa Daylight Time",
1333  "Africa/Harare"
1334  },
1335  {
1336  /* (UTC+05:30) Sri Jayawardenepura */
1337  "Sri Lanka Standard Time", "Sri Lanka Daylight Time",
1338  "Asia/Colombo"
1339  },
1340  {
1341  /* (UTC+02:00) Khartoum */
1342  "Sudan Standard Time", "Sudan Daylight Time",
1343  "Africa/Khartoum"
1344  },
1345  {
1346  /* (UTC+02:00) Damascus */
1347  "Syria Standard Time", "Syria Daylight Time",
1348  "Asia/Damascus"
1349  },
1350  {
1351  /* (UTC+08:00) Taipei */
1352  "Taipei Standard Time", "Taipei Daylight Time",
1353  "Asia/Taipei"
1354  },
1355  {
1356  /* (UTC+10:00) Hobart */
1357  "Tasmania Standard Time", "Tasmania Daylight Time",
1358  "Australia/Hobart"
1359  },
1360  {
1361  /* (UTC-03:00) Araguaina */
1362  "Tocantins Standard Time", "Tocantins Daylight Time",
1363  "America/Araguaina"
1364  },
1365  {
1366  /* (UTC+09:00) Osaka, Sapporo, Tokyo */
1367  "Tokyo Standard Time", "Tokyo Daylight Time",
1368  "Asia/Tokyo"
1369  },
1370  {
1371  /* (UTC+13:00) Nuku'alofa */
1372  "Tonga Standard Time", "Tonga Daylight Time",
1373  "Pacific/Tongatapu"
1374  },
1375  {
1376  /* (UTC+07:00) Tomsk */
1377  "Tomsk Standard Time", "Tomsk Daylight Time",
1378  "Asia/Tomsk"
1379  },
1380  {
1381  /* (UTC+09:00) Chita */
1382  "Transbaikal Standard Time", "Transbaikal Daylight Time",
1383  "Asia/Chita"
1384  },
1385  {
1386  /* (UTC+03:00) Istanbul */
1387  "Turkey Standard Time", "Turkey Daylight Time",
1388  "Europe/Istanbul"
1389  },
1390  {
1391  /* (UTC-05:00) Turks and Caicos */
1392  "Turks and Caicos Standard Time", "Turks and Caicos Daylight Time",
1393  "America/Grand_Turk"
1394  },
1395  {
1396  /* (UTC+08:00) Ulaanbaatar */
1397  "Ulaanbaatar Standard Time", "Ulaanbaatar Daylight Time",
1398  "Asia/Ulaanbaatar",
1399  },
1400  {
1401  /* (UTC-05:00) Indiana (East) */
1402  "US Eastern Standard Time", "US Eastern Daylight Time",
1403  "US/Eastern"
1404  },
1405  {
1406  /* (UTC-07:00) Arizona */
1407  "US Mountain Standard Time", "US Mountain Daylight Time",
1408  "US/Arizona"
1409  },
1410  {
1411  /* (UTC) Coordinated Universal Time */
1412  "Coordinated Universal Time", "Coordinated Universal Time",
1413  "UTC"
1414  },
1415  {
1416  /* (UTC+12:00) Coordinated Universal Time+12 */
1417  "UTC+12", "UTC+12",
1418  "Etc/GMT+12"
1419  },
1420  {
1421  /* (UTC+13:00) Coordinated Universal Time+13 */
1422  "UTC+13", "UTC+13",
1423  "Etc/GMT+13"
1424  },
1425  {
1426  /* (UTC-02:00) Coordinated Universal Time-02 */
1427  "UTC-02", "UTC-02",
1428  "Etc/GMT-02"
1429  },
1430  {
1431  /* (UTC-08:00) Coordinated Universal Time-08 */
1432  "UTC-08", "UTC-08",
1433  "Etc/GMT-08"
1434  },
1435  {
1436  /* (UTC-09:00) Coordinated Universal Time-09 */
1437  "UTC-09", "UTC-09",
1438  "Etc/GMT-09"
1439  },
1440  {
1441  /* (UTC-11:00) Coordinated Universal Time-11 */
1442  "UTC-11", "UTC-11",
1443  "Etc/GMT-11"
1444  },
1445  {
1446  /* (UTC-04:00) Caracas */
1447  "Venezuela Standard Time", "Venezuela Daylight Time",
1448  "America/Caracas",
1449  },
1450  {
1451  /* (UTC+10:00) Vladivostok (RTZ 9) */
1452  "Vladivostok Standard Time", "Vladivostok Daylight Time",
1453  "Asia/Vladivostok"
1454  },
1455  {
1456  /* (UTC+04:00) Volgograd */
1457  "Volgograd Standard Time", "Volgograd Daylight Time",
1458  "Europe/Volgograd"
1459  },
1460  {
1461  /* (UTC+08:00) Perth */
1462  "W. Australia Standard Time", "W. Australia Daylight Time",
1463  "Australia/Perth"
1464  },
1465 #ifdef NOT_USED
1466  /* Could not find a match for this one (just a guess). Excluded for now. */
1467  {
1468  /* (UTC+01:00) West Central Africa */
1469  "W. Central Africa Standard Time", "W. Central Africa Daylight Time",
1470  "WAT"
1471  },
1472 #endif
1473  {
1474  /* (UTC+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna */
1475  "W. Europe Standard Time", "W. Europe Daylight Time",
1476  "CET"
1477  },
1478  {
1479  /* (UTC+07:00) Hovd */
1480  "W. Mongolia Standard Time", "W. Mongolia Daylight Time",
1481  "Asia/Hovd"
1482  },
1483  {
1484  /* (UTC+05:00) Ashgabat, Tashkent */
1485  "West Asia Standard Time", "West Asia Daylight Time",
1486  "Asia/Karachi"
1487  },
1488  {
1489  /* (UTC+02:00) Gaza, Hebron */
1490  "West Bank Gaza Standard Time", "West Bank Gaza Daylight Time",
1491  "Asia/Gaza"
1492  },
1493  {
1494  /* (UTC+10:00) Guam, Port Moresby */
1495  "West Pacific Standard Time", "West Pacific Daylight Time",
1496  "Pacific/Guam"
1497  },
1498  {
1499  /* (UTC+09:00) Yakutsk */
1500  "Yakutsk Standard Time", "Yakutsk Daylight Time",
1501  "Asia/Yakutsk"
1502  },
1503  {
1504  NULL, NULL, NULL
1505  }
1506 };
1507 
1508 static const char *
1510 {
1511  int i;
1512  char tzname[128];
1513  char localtzname[256];
1514  time_t t = time(NULL);
1515  struct tm *tm = localtime(&t);
1516  HKEY rootKey;
1517  int idx;
1518 
1519  if (!tm)
1520  {
1521 #ifdef DEBUG_IDENTIFY_TIMEZONE
1522  fprintf(stderr, "could not identify system time zone: localtime() failed\n");
1523 #endif
1524  return NULL; /* go to GMT */
1525  }
1526 
1527  memset(tzname, 0, sizeof(tzname));
1528  strftime(tzname, sizeof(tzname) - 1, "%Z", tm);
1529 
1530  for (i = 0; win32_tzmap[i].stdname != NULL; i++)
1531  {
1532  if (strcmp(tzname, win32_tzmap[i].stdname) == 0 ||
1533  strcmp(tzname, win32_tzmap[i].dstname) == 0)
1534  {
1535 #ifdef DEBUG_IDENTIFY_TIMEZONE
1536  fprintf(stderr, "TZ \"%s\" matches system time zone \"%s\"\n",
1537  win32_tzmap[i].pgtzname, tzname);
1538 #endif
1539  return win32_tzmap[i].pgtzname;
1540  }
1541  }
1542 
1543  /*
1544  * Localized Windows versions return localized names for the timezone.
1545  * Scan the registry to find the English name, and then try matching
1546  * against our table again.
1547  */
1548  memset(localtzname, 0, sizeof(localtzname));
1549  if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
1550  "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
1551  0,
1552  KEY_READ,
1553  &rootKey) != ERROR_SUCCESS)
1554  {
1555 #ifdef DEBUG_IDENTIFY_TIMEZONE
1556  fprintf(stderr, "could not open registry key to identify system time zone: error code %lu\n",
1557  GetLastError());
1558 #endif
1559  return NULL; /* go to GMT */
1560  }
1561 
1562  for (idx = 0;; idx++)
1563  {
1564  char keyname[256];
1565  char zonename[256];
1566  DWORD namesize;
1567  FILETIME lastwrite;
1568  HKEY key;
1569  LONG r;
1570 
1571  memset(keyname, 0, sizeof(keyname));
1572  namesize = sizeof(keyname);
1573  if ((r = RegEnumKeyEx(rootKey,
1574  idx,
1575  keyname,
1576  &namesize,
1577  NULL,
1578  NULL,
1579  NULL,
1580  &lastwrite)) != ERROR_SUCCESS)
1581  {
1582  if (r == ERROR_NO_MORE_ITEMS)
1583  break;
1584 #ifdef DEBUG_IDENTIFY_TIMEZONE
1585  fprintf(stderr, "could not enumerate registry subkeys to identify system time zone: %d\n",
1586  (int) r);
1587 #endif
1588  break;
1589  }
1590 
1591  if ((r = RegOpenKeyEx(rootKey, keyname, 0, KEY_READ, &key)) != ERROR_SUCCESS)
1592  {
1593 #ifdef DEBUG_IDENTIFY_TIMEZONE
1594  fprintf(stderr, "could not open registry subkey to identify system time zone: %d\n",
1595  (int) r);
1596 #endif
1597  break;
1598  }
1599 
1600  memset(zonename, 0, sizeof(zonename));
1601  namesize = sizeof(zonename);
1602  if ((r = RegQueryValueEx(key, "Std", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
1603  {
1604 #ifdef DEBUG_IDENTIFY_TIMEZONE
1605  fprintf(stderr, "could not query value for key \"std\" to identify system time zone \"%s\": %d\n",
1606  keyname, (int) r);
1607 #endif
1608  RegCloseKey(key);
1609  continue; /* Proceed to look at the next timezone */
1610  }
1611  if (strcmp(tzname, zonename) == 0)
1612  {
1613  /* Matched zone */
1614  strcpy(localtzname, keyname);
1615  RegCloseKey(key);
1616  break;
1617  }
1618  memset(zonename, 0, sizeof(zonename));
1619  namesize = sizeof(zonename);
1620  if ((r = RegQueryValueEx(key, "Dlt", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
1621  {
1622 #ifdef DEBUG_IDENTIFY_TIMEZONE
1623  fprintf(stderr, "could not query value for key \"dlt\" to identify system time zone \"%s\": %d\n",
1624  keyname, (int) r);
1625 #endif
1626  RegCloseKey(key);
1627  continue; /* Proceed to look at the next timezone */
1628  }
1629  if (strcmp(tzname, zonename) == 0)
1630  {
1631  /* Matched DST zone */
1632  strcpy(localtzname, keyname);
1633  RegCloseKey(key);
1634  break;
1635  }
1636 
1637  RegCloseKey(key);
1638  }
1639 
1640  RegCloseKey(rootKey);
1641 
1642  if (localtzname[0])
1643  {
1644  /* Found a localized name, so scan for that one too */
1645  for (i = 0; win32_tzmap[i].stdname != NULL; i++)
1646  {
1647  if (strcmp(localtzname, win32_tzmap[i].stdname) == 0 ||
1648  strcmp(localtzname, win32_tzmap[i].dstname) == 0)
1649  {
1650 #ifdef DEBUG_IDENTIFY_TIMEZONE
1651  fprintf(stderr, "TZ \"%s\" matches localized system time zone \"%s\" (\"%s\")\n",
1652  win32_tzmap[i].pgtzname, tzname, localtzname);
1653 #endif
1654  return win32_tzmap[i].pgtzname;
1655  }
1656  }
1657  }
1658 
1659 #ifdef DEBUG_IDENTIFY_TIMEZONE
1660  fprintf(stderr, "could not find a match for system time zone \"%s\"\n",
1661  tzname);
1662 #endif
1663  return NULL; /* go to GMT */
1664 }
1665 #endif /* WIN32 */
1666 
1667 
1668 /*
1669  * Return true if the given zone name is valid and is an "acceptable" zone.
1670  */
1671 static bool
1672 validate_zone(const char *tzname)
1673 {
1674  pg_tz *tz;
1675 
1676  if (!tzname || !tzname[0])
1677  return false;
1678 
1679  tz = pg_load_tz(tzname);
1680  if (!tz)
1681  return false;
1682 
1683  if (!pg_tz_acceptable(tz))
1684  return false;
1685 
1686  return true;
1687 }
1688 
1689 /*
1690  * Identify a suitable default timezone setting based on the environment.
1691  *
1692  * The installation share_path must be passed in, as that is the default
1693  * location for the timezone database directory.
1694  *
1695  * We first look to the TZ environment variable. If not found or not
1696  * recognized by our own code, we see if we can identify the timezone
1697  * from the behavior of the system timezone library. When all else fails,
1698  * return NULL, indicating that we should default to GMT.
1699  */
1700 const char *
1702 {
1703  const char *tzname;
1704 
1705  /* Initialize timezone directory path, if needed */
1706 #ifndef SYSTEMTZDIR
1707  snprintf(tzdirpath, sizeof(tzdirpath), "%s/timezone", share_path);
1708 #endif
1709 
1710  /* Check TZ environment variable */
1711  tzname = getenv("TZ");
1712  if (validate_zone(tzname))
1713  return tzname;
1714 
1715  /* Nope, so try to identify the system timezone */
1716  tzname = identify_system_timezone();
1717  if (validate_zone(tzname))
1718  return tzname;
1719 
1720  return NULL;
1721 }
#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:656
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:223
#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:197
static const char * pg_TZDIR(void)
Definition: findtimezone.c:37
#define PG_BINARY
Definition: c.h:1211
static int zone_name_pref(const char *zonename)
Definition: findtimezone.c:614
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:206
static bool perfect_timezone_match(const char *tzname, struct tztry *tt)
Definition: findtimezone.c:319
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Definition: pgtime.h:30
int tm_mon
Definition: pgtime.h:31
#define readlink(path, buf, size)
Definition: win32_port.h:222
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
#define stat(a, b)
Definition: win32_port.h:255
static int score_timezone(const char *tzname, struct tztry *tt)
Definition: findtimezone.c:233
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
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:206
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:543
struct pg_tm * pg_localtime(const pg_time_t *timep, const pg_tz *tz)
Definition: localtime.c:1342
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Definition: encode.c:561
#define S_ISDIR(m)
Definition: win32_port.h:296
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Definition: pgtime.h:32
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static const char * identify_system_timezone(void)
Definition: findtimezone.c:330
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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:193
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Definition: pgtime.h:28
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Definition: findtimezone.c:156