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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) 1996-2017, 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 
19 #include "pgtz.h"
20 
21 /* Ideally this would be in a .h file, but it hardly seems worth the trouble */
22 extern const char *select_default_timezone(const char *share_path);
23 
24 
25 #ifndef SYSTEMTZDIR
26 static char tzdirpath[MAXPGPATH];
27 #endif
28 
29 
30 /*
31  * Return full pathname of timezone data directory
32  *
33  * In this file, tzdirpath is assumed to be set up by select_default_timezone.
34  */
35 static const char *
36 pg_TZDIR(void)
37 {
38 #ifndef SYSTEMTZDIR
39  /* normal case: timezone stuff is under our share dir */
40  return tzdirpath;
41 #else
42  /* we're configured to use system's timezone database */
43  return SYSTEMTZDIR;
44 #endif
45 }
46 
47 
48 /*
49  * Given a timezone name, open() the timezone data file. Return the
50  * file descriptor if successful, -1 if not.
51  *
52  * This is simpler than the backend function of the same name because
53  * we assume that the input string has the correct case already, so there
54  * is no need for case-folding. (This is obviously true if we got the file
55  * name from the filesystem to start with. The only other place it can come
56  * from is the environment variable TZ, and there seems no need to allow
57  * case variation in that; other programs aren't likely to.)
58  *
59  * If "canonname" is not NULL, then on success the canonical spelling of the
60  * given name is stored there (the buffer must be > TZ_STRLEN_MAX bytes!).
61  * This is redundant but kept for compatibility with the backend code.
62  */
63 int
64 pg_open_tzfile(const char *name, char *canonname)
65 {
66  char fullname[MAXPGPATH];
67 
68  if (canonname)
69  strlcpy(canonname, name, TZ_STRLEN_MAX + 1);
70 
71  strlcpy(fullname, pg_TZDIR(), sizeof(fullname));
72  if (strlen(fullname) + 1 + strlen(name) >= MAXPGPATH)
73  return -1; /* not gonna fit */
74  strcat(fullname, "/");
75  strcat(fullname, name);
76 
77  return open(fullname, O_RDONLY | PG_BINARY, 0);
78 }
79 
80 
81 
82 /*
83  * Load a timezone definition.
84  * Does not verify that the timezone is acceptable!
85  *
86  * This corresponds to the backend's pg_tzset(), except that we only support
87  * one loaded timezone at a time.
88  */
89 static pg_tz *
90 pg_load_tz(const char *name)
91 {
92  static pg_tz tz;
93 
94  if (strlen(name) > TZ_STRLEN_MAX)
95  return NULL; /* not going to fit */
96 
97  /*
98  * "GMT" is always sent to tzparse(); see comments for pg_tzset().
99  */
100  if (strcmp(name, "GMT") == 0)
101  {
102  if (!tzparse(name, &tz.state, true))
103  {
104  /* This really, really should not happen ... */
105  return NULL;
106  }
107  }
108  else if (tzload(name, NULL, &tz.state, true) != 0)
109  {
110  if (name[0] == ':' || !tzparse(name, &tz.state, false))
111  {
112  return NULL; /* unknown timezone */
113  }
114  }
115 
116  strcpy(tz.TZname, name);
117 
118  return &tz;
119 }
120 
121 
122 /*
123  * The following block of code attempts to determine which timezone in our
124  * timezone database is the best match for the active system timezone.
125  *
126  * On most systems, we rely on trying to match the observable behavior of
127  * the C library's localtime() function. The database zone that matches
128  * furthest into the past is the one to use. Often there will be several
129  * zones with identical rankings (since the Olson database assigns multiple
130  * names to many zones). We break ties arbitrarily by preferring shorter,
131  * then alphabetically earlier zone names.
132  *
133  * Win32's native knowledge about timezones appears to be too incomplete
134  * and too different from the Olson database for the above matching strategy
135  * to be of any use. But there is just a limited number of timezones
136  * available, so we can rely on a handmade mapping table instead.
137  */
138 
139 #ifndef WIN32
140 
141 #define T_DAY ((time_t) (60*60*24))
142 #define T_WEEK ((time_t) (60*60*24*7))
143 #define T_MONTH ((time_t) (60*60*24*31))
144 
145 #define MAX_TEST_TIMES (52*100) /* 100 years */
146 
147 struct tztry
148 {
151 };
152 
153 static void scan_available_timezones(char *tzdir, char *tzdirsub,
154  struct tztry *tt,
155  int *bestscore, char *bestzonename);
156 
157 
158 /*
159  * Get GMT offset from a system struct tm
160  */
161 static int
163 {
164 #if defined(HAVE_STRUCT_TM_TM_ZONE)
165  return tm->tm_gmtoff;
166 #elif defined(HAVE_INT_TIMEZONE)
167  return -TIMEZONE_GLOBAL;
168 #else
169 #error No way to determine TZ? Can this happen?
170 #endif
171 }
172 
173 /*
174  * Convenience subroutine to convert y/m/d to time_t (NOT pg_time_t)
175  */
176 static time_t
177 build_time_t(int year, int month, int day)
178 {
179  struct tm tm;
180 
181  memset(&tm, 0, sizeof(tm));
182  tm.tm_mday = day;
183  tm.tm_mon = month - 1;
184  tm.tm_year = year - 1900;
185 
186  return mktime(&tm);
187 }
188 
189 /*
190  * Does a system tm value match one we computed ourselves?
191  */
192 static bool
193 compare_tm(struct tm *s, struct pg_tm *p)
194 {
195  if (s->tm_sec != p->tm_sec ||
196  s->tm_min != p->tm_min ||
197  s->tm_hour != p->tm_hour ||
198  s->tm_mday != p->tm_mday ||
199  s->tm_mon != p->tm_mon ||
200  s->tm_year != p->tm_year ||
201  s->tm_wday != p->tm_wday ||
202  s->tm_yday != p->tm_yday ||
203  s->tm_isdst != p->tm_isdst)
204  return false;
205  return true;
206 }
207 
208 /*
209  * See how well a specific timezone setting matches the system behavior
210  *
211  * We score a timezone setting according to the number of test times it
212  * matches. (The test times are ordered later-to-earlier, but this routine
213  * doesn't actually know that; it just scans until the first non-match.)
214  *
215  * We return -1 for a completely unusable setting; this is worse than the
216  * score of zero for a setting that works but matches not even the first
217  * test time.
218  */
219 static int
220 score_timezone(const char *tzname, struct tztry *tt)
221 {
222  int i;
223  pg_time_t pgtt;
224  struct tm *systm;
225  struct pg_tm *pgtm;
226  char cbuf[TZ_STRLEN_MAX + 1];
227  pg_tz *tz;
228 
229  /* Load timezone definition */
230  tz = pg_load_tz(tzname);
231  if (!tz)
232  return -1; /* unrecognized zone name */
233 
234  /* Reject if leap seconds involved */
235  if (!pg_tz_acceptable(tz))
236  {
237 #ifdef DEBUG_IDENTIFY_TIMEZONE
238  fprintf(stderr, "Reject TZ \"%s\": uses leap seconds\n", tzname);
239 #endif
240  return -1;
241  }
242 
243  /* Check for match at all the test times */
244  for (i = 0; i < tt->n_test_times; i++)
245  {
246  pgtt = (pg_time_t) (tt->test_times[i]);
247  pgtm = pg_localtime(&pgtt, tz);
248  if (!pgtm)
249  return -1; /* probably shouldn't happen */
250  systm = localtime(&(tt->test_times[i]));
251  if (!systm)
252  {
253 #ifdef DEBUG_IDENTIFY_TIMEZONE
254  fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s, system had no data\n",
255  tzname, i, (long) pgtt,
256  pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
257  pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
258  pgtm->tm_isdst ? "dst" : "std");
259 #endif
260  return i;
261  }
262  if (!compare_tm(systm, pgtm))
263  {
264 #ifdef DEBUG_IDENTIFY_TIMEZONE
265  fprintf(stderr, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s versus %04d-%02d-%02d %02d:%02d:%02d %s\n",
266  tzname, i, (long) pgtt,
267  pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
268  pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
269  pgtm->tm_isdst ? "dst" : "std",
270  systm->tm_year + 1900, systm->tm_mon + 1, systm->tm_mday,
271  systm->tm_hour, systm->tm_min, systm->tm_sec,
272  systm->tm_isdst ? "dst" : "std");
273 #endif
274  return i;
275  }
276  if (systm->tm_isdst >= 0)
277  {
278  /* Check match of zone names, too */
279  if (pgtm->tm_zone == NULL)
280  return -1; /* probably shouldn't happen */
281  memset(cbuf, 0, sizeof(cbuf));
282  strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm); /* zone abbr */
283  if (strcmp(cbuf, pgtm->tm_zone) != 0)
284  {
285 #ifdef DEBUG_IDENTIFY_TIMEZONE
286  fprintf(stderr, "TZ \"%s\" scores %d: at %ld \"%s\" versus \"%s\"\n",
287  tzname, i, (long) pgtt,
288  pgtm->tm_zone, cbuf);
289 #endif
290  return i;
291  }
292  }
293  }
294 
295 #ifdef DEBUG_IDENTIFY_TIMEZONE
296  fprintf(stderr, "TZ \"%s\" gets max score %d\n", tzname, i);
297 #endif
298 
299  return i;
300 }
301 
302 
303 /*
304  * Try to identify a timezone name (in our terminology) that best matches the
305  * observed behavior of the system timezone library. We cannot assume that
306  * the system TZ environment setting (if indeed there is one) matches our
307  * terminology, so we ignore it and just look at what localtime() returns.
308  */
309 static const char *
311 {
312  static char resultbuf[TZ_STRLEN_MAX + 1];
313  time_t tnow;
314  time_t t;
315  struct tztry tt;
316  struct tm *tm;
317  int thisyear;
318  int bestscore;
319  char tmptzdir[MAXPGPATH];
320  int std_ofs;
321  char std_zone_name[TZ_STRLEN_MAX + 1],
322  dst_zone_name[TZ_STRLEN_MAX + 1];
323  char cbuf[TZ_STRLEN_MAX + 1];
324 
325  /* Initialize OS timezone library */
326  tzset();
327 
328  /*
329  * Set up the list of dates to be probed to see how well our timezone
330  * matches the system zone. We first probe January and July of the
331  * current year; this serves to quickly eliminate the vast majority of the
332  * TZ database entries. If those dates match, we probe every week for 100
333  * years backwards from the current July. (Weekly resolution is good
334  * enough to identify DST transition rules, since everybody switches on
335  * Sundays.) This is sufficient to cover most of the Unix time_t range,
336  * and we don't want to look further than that since many systems won't
337  * have sane TZ behavior further back anyway. The further back the zone
338  * matches, the better we score it. This may seem like a rather random
339  * way of doing things, but experience has shown that system-supplied
340  * timezone definitions are likely to have DST behavior that is right for
341  * the recent past and not so accurate further back. Scoring in this way
342  * allows us to recognize zones that have some commonality with the Olson
343  * database, without insisting on exact match. (Note: we probe Thursdays,
344  * not Sundays, to avoid triggering DST-transition bugs in localtime
345  * itself.)
346  */
347  tnow = time(NULL);
348  tm = localtime(&tnow);
349  if (!tm)
350  return NULL; /* give up if localtime is broken... */
351  thisyear = tm->tm_year + 1900;
352 
353  t = build_time_t(thisyear, 1, 15);
354 
355  /*
356  * Round back to GMT midnight Thursday. This depends on the knowledge
357  * that the time_t origin is Thu Jan 01 1970. (With a different origin
358  * we'd be probing some other day of the week, but it wouldn't matter
359  * anyway unless localtime() had DST-transition bugs.)
360  */
361  t -= (t % T_WEEK);
362 
363  tt.n_test_times = 0;
364  tt.test_times[tt.n_test_times++] = t;
365 
366  t = build_time_t(thisyear, 7, 15);
367  t -= (t % T_WEEK);
368 
369  tt.test_times[tt.n_test_times++] = t;
370 
371  while (tt.n_test_times < MAX_TEST_TIMES)
372  {
373  t -= T_WEEK;
374  tt.test_times[tt.n_test_times++] = t;
375  }
376 
377  /* Search for the best-matching timezone file */
378  strlcpy(tmptzdir, pg_TZDIR(), sizeof(tmptzdir));
379  bestscore = -1;
380  resultbuf[0] = '\0';
381  scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1,
382  &tt,
383  &bestscore, resultbuf);
384  if (bestscore > 0)
385  {
386  /* Ignore Olson's rather silly "Factory" zone; use GMT instead */
387  if (strcmp(resultbuf, "Factory") == 0)
388  return NULL;
389  return resultbuf;
390  }
391 
392  /*
393  * Couldn't find a match in the database, so next we try constructed zone
394  * names (like "PST8PDT").
395  *
396  * First we need to determine the names of the local standard and daylight
397  * zones. The idea here is to scan forward from today until we have seen
398  * both zones, if both are in use.
399  */
400  memset(std_zone_name, 0, sizeof(std_zone_name));
401  memset(dst_zone_name, 0, sizeof(dst_zone_name));
402  std_ofs = 0;
403 
404  tnow = time(NULL);
405 
406  /*
407  * Round back to a GMT midnight so results don't depend on local time of
408  * day
409  */
410  tnow -= (tnow % T_DAY);
411 
412  /*
413  * We have to look a little further ahead than one year, in case today is
414  * just past a DST boundary that falls earlier in the year than the next
415  * similar boundary. Arbitrarily scan up to 14 months.
416  */
417  for (t = tnow; t <= tnow + T_MONTH * 14; t += T_MONTH)
418  {
419  tm = localtime(&t);
420  if (!tm)
421  continue;
422  if (tm->tm_isdst < 0)
423  continue;
424  if (tm->tm_isdst == 0 && std_zone_name[0] == '\0')
425  {
426  /* found STD zone */
427  memset(cbuf, 0, sizeof(cbuf));
428  strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
429  strcpy(std_zone_name, cbuf);
430  std_ofs = get_timezone_offset(tm);
431  }
432  if (tm->tm_isdst > 0 && dst_zone_name[0] == '\0')
433  {
434  /* found DST zone */
435  memset(cbuf, 0, sizeof(cbuf));
436  strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
437  strcpy(dst_zone_name, cbuf);
438  }
439  /* Done if found both */
440  if (std_zone_name[0] && dst_zone_name[0])
441  break;
442  }
443 
444  /* We should have found a STD zone name by now... */
445  if (std_zone_name[0] == '\0')
446  {
447 #ifdef DEBUG_IDENTIFY_TIMEZONE
448  fprintf(stderr, "could not determine system time zone\n");
449 #endif
450  return NULL; /* go to GMT */
451  }
452 
453  /* If we found DST then try STD<ofs>DST */
454  if (dst_zone_name[0] != '\0')
455  {
456  snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
457  std_zone_name, -std_ofs / 3600, dst_zone_name);
458  if (score_timezone(resultbuf, &tt) > 0)
459  return resultbuf;
460  }
461 
462  /* Try just the STD timezone (works for GMT at least) */
463  strcpy(resultbuf, std_zone_name);
464  if (score_timezone(resultbuf, &tt) > 0)
465  return resultbuf;
466 
467  /* Try STD<ofs> */
468  snprintf(resultbuf, sizeof(resultbuf), "%s%d",
469  std_zone_name, -std_ofs / 3600);
470  if (score_timezone(resultbuf, &tt) > 0)
471  return resultbuf;
472 
473  /*
474  * Did not find the timezone. Fallback to use a GMT zone. Note that the
475  * Olson timezone database names the GMT-offset zones in POSIX style: plus
476  * is west of Greenwich. It's unfortunate that this is opposite of SQL
477  * conventions. Should we therefore change the names? Probably not...
478  */
479  snprintf(resultbuf, sizeof(resultbuf), "Etc/GMT%s%d",
480  (-std_ofs > 0) ? "+" : "", -std_ofs / 3600);
481 
482 #ifdef DEBUG_IDENTIFY_TIMEZONE
483  fprintf(stderr, "could not recognize system time zone, using \"%s\"\n",
484  resultbuf);
485 #endif
486  return resultbuf;
487 }
488 
489 /*
490  * Recursively scan the timezone database looking for the best match to
491  * the system timezone behavior.
492  *
493  * tzdir points to a buffer of size MAXPGPATH. On entry, it holds the
494  * pathname of a directory containing TZ files. We internally modify it
495  * to hold pathnames of sub-directories and files, but must restore it
496  * to its original contents before exit.
497  *
498  * tzdirsub points to the part of tzdir that represents the subfile name
499  * (ie, tzdir + the original directory name length, plus one for the
500  * first added '/').
501  *
502  * tt tells about the system timezone behavior we need to match.
503  *
504  * *bestscore and *bestzonename on entry hold the best score found so far
505  * and the name of the best zone. We overwrite them if we find a better
506  * score. bestzonename must be a buffer of length TZ_STRLEN_MAX + 1.
507  */
508 static void
509 scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt,
510  int *bestscore, char *bestzonename)
511 {
512  int tzdir_orig_len = strlen(tzdir);
513  char **names;
514  char **namep;
515 
516  names = pgfnames(tzdir);
517  if (!names)
518  return;
519 
520  for (namep = names; *namep; namep++)
521  {
522  char *name = *namep;
523  struct stat statbuf;
524 
525  /* Ignore . and .., plus any other "hidden" files */
526  if (name[0] == '.')
527  continue;
528 
529  snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
530  "/%s", name);
531 
532  if (stat(tzdir, &statbuf) != 0)
533  {
534 #ifdef DEBUG_IDENTIFY_TIMEZONE
535  fprintf(stderr, "could not stat \"%s\": %s\n",
536  tzdir, strerror(errno));
537 #endif
538  tzdir[tzdir_orig_len] = '\0';
539  continue;
540  }
541 
542  if (S_ISDIR(statbuf.st_mode))
543  {
544  /* Recurse into subdirectory */
545  scan_available_timezones(tzdir, tzdirsub, tt,
546  bestscore, bestzonename);
547  }
548  else
549  {
550  /* Load and test this file */
551  int score = score_timezone(tzdirsub, tt);
552 
553  if (score > *bestscore)
554  {
555  *bestscore = score;
556  strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
557  }
558  else if (score == *bestscore)
559  {
560  /* Consider how to break a tie */
561  if (strlen(tzdirsub) < strlen(bestzonename) ||
562  (strlen(tzdirsub) == strlen(bestzonename) &&
563  strcmp(tzdirsub, bestzonename) < 0))
564  strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
565  }
566  }
567 
568  /* Restore tzdir */
569  tzdir[tzdir_orig_len] = '\0';
570  }
571 
572  pgfnames_cleanup(names);
573 }
574 #else /* WIN32 */
575 
576 static const struct
577 {
578  const char *stdname; /* Windows name of standard timezone */
579  const char *dstname; /* Windows name of daylight timezone */
580  const char *pgtzname; /* Name of pgsql timezone to map to */
581 } win32_tzmap[] =
582 
583 {
584  /*
585  * This list was built from the contents of the registry at
586  * HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time
587  * Zones on Windows 10 and Windows 7.
588  *
589  * The zones have been matched to Olson timezones by looking at the cities
590  * listed in the win32 display name (in the comment here) in most cases.
591  */
592  {
593  "Afghanistan Standard Time", "Afghanistan Daylight Time",
594  "Asia/Kabul"
595  }, /* (UTC+04:30) Kabul */
596  {
597  "Alaskan Standard Time", "Alaskan Daylight Time",
598  "US/Alaska"
599  }, /* (UTC-09:00) Alaska */
600  {
601  "Aleutian Standard Time", "Aleutian Daylight Time",
602  "US/Aleutan"
603  }, /* (UTC-10:00) Aleutian Islands */
604  {
605  "Altai Standard Time", "Altai Daylight Time",
606  "Asia/Barnaul"
607  }, /* (UTC+07:00) Barnaul, Gorno-Altaysk */
608  {
609  "Arab Standard Time", "Arab Daylight Time",
610  "Asia/Kuwait"
611  }, /* (UTC+03:00) Kuwait, Riyadh */
612  {
613  "Arabian Standard Time", "Arabian Daylight Time",
614  "Asia/Muscat"
615  }, /* (UTC+04:00) Abu Dhabi, Muscat */
616  {
617  "Arabic Standard Time", "Arabic Daylight Time",
618  "Asia/Baghdad"
619  }, /* (UTC+03:00) Baghdad */
620  {
621  "Argentina Standard Time", "Argentina Daylight Time",
622  "America/Buenos_Aires"
623  }, /* (UTC-03:00) City of Buenos Aires */
624  {
625  "Armenian Standard Time", "Armenian Daylight Time",
626  "Asia/Yerevan"
627  }, /* (UTC+04:00) Baku, Tbilisi, Yerevan */
628  {
629  "Astrakhan Standard Time", "Astrakhan Daylight Time",
630  "Europe/Astrakhan"
631  }, /* (UTC+04:00) Astrakhan, Ulyanovsk */
632  {
633  "Atlantic Standard Time", "Atlantic Daylight Time",
634  "Canada/Atlantic"
635  }, /* (UTC-04:00) Atlantic Time (Canada) */
636  {
637  "AUS Central Standard Time", "AUS Central Daylight Time",
638  "Australia/Darwin"
639  }, /* (UTC+09:30) Darwin */
640  {
641  "Aus Central W. Standard Time", "Aus Central W. Daylight Time",
642  "Australia/Eucla"
643  }, /* (UTC+08:45) Eucla */
644  {
645  "AUS Eastern Standard Time", "AUS Eastern Daylight Time",
646  "Australia/Canberra"
647  }, /* (UTC+10:00) Canberra, Melbourne, Sydney */
648  {
649  "Azerbaijan Standard Time", "Azerbaijan Daylight Time",
650  "Asia/Baku"
651  }, /* (UTC+04:00) Baku */
652  {
653  "Azores Standard Time", "Azores Daylight Time",
654  "Atlantic/Azores"
655  }, /* (UTC-01:00) Azores */
656  {
657  "Bahia Standard Time", "Bahia Daylight Time",
658  "America/Salvador"
659  }, /* (UTC-03:00) Salvador */
660  {
661  "Bangladesh Standard Time", "Bangladesh Daylight Time",
662  "Asia/Dhaka"
663  }, /* (UTC+06:00) Dhaka */
664  {
665  "Bougainville Standard Time", "Bougainville Daylight Time",
666  "Pacific/Bougainville"
667  }, /* (UTC+11:00) Bougainville Island */
668  {
669  "Belarus Standard Time", "Belarus Daylight Time",
670  "Europe/Minsk"
671  }, /* (UTC+03:00) Minsk */
672  {
673  "Cabo Verde Standard Time", "Cabo Verde Daylight Time",
674  "Atlantic/Cape_Verde"
675  }, /* (UTC-01:00) Cabo Verde Is. */
676  {
677  "Chatham Islands Standard Time", "Chatham Islands Daylight Time",
678  "Pacific/Chatham"
679  }, /* (UTC+12:45) Chatham Islands */
680  {
681  "Canada Central Standard Time", "Canada Central Daylight Time",
682  "Canada/Saskatchewan"
683  }, /* (UTC-06:00) Saskatchewan */
684  {
685  "Cape Verde Standard Time", "Cape Verde Daylight Time",
686  "Atlantic/Cape_Verde"
687  }, /* (UTC-01:00) Cape Verde Is. */
688  {
689  "Caucasus Standard Time", "Caucasus Daylight Time",
690  "Asia/Baku"
691  }, /* (UTC+04:00) Yerevan */
692  {
693  "Cen. Australia Standard Time", "Cen. Australia Daylight Time",
694  "Australia/Adelaide"
695  }, /* (UTC+09:30) Adelaide */
696  /* Central America (other than Mexico) generally does not observe DST */
697  {
698  "Central America Standard Time", "Central America Daylight Time",
699  "CST6"
700  }, /* (UTC-06:00) Central America */
701  {
702  "Central Asia Standard Time", "Central Asia Daylight Time",
703  "Asia/Dhaka"
704  }, /* (UTC+06:00) Astana */
705  {
706  "Central Brazilian Standard Time", "Central Brazilian Daylight Time",
707  "America/Cuiaba"
708  }, /* (UTC-04:00) Cuiaba */
709  {
710  "Central Europe Standard Time", "Central Europe Daylight Time",
711  "Europe/Belgrade"
712  }, /* (UTC+01:00) Belgrade, Bratislava, Budapest,
713  * Ljubljana, Prague */
714  {
715  "Central European Standard Time", "Central European Daylight Time",
716  "Europe/Sarajevo"
717  }, /* (UTC+01:00) Sarajevo, Skopje, Warsaw,
718  * Zagreb */
719  {
720  "Central Pacific Standard Time", "Central Pacific Daylight Time",
721  "Pacific/Noumea"
722  }, /* (UTC+11:00) Solomon Is., New Caledonia */
723  {
724  "Central Standard Time", "Central Daylight Time",
725  "US/Central"
726  }, /* (UTC-06:00) Central Time (US & Canada) */
727  {
728  "Central Standard Time (Mexico)", "Central Daylight Time (Mexico)",
729  "America/Mexico_City"
730  }, /* (UTC-06:00) Guadalajara, Mexico City,
731  * Monterrey */
732  {
733  "China Standard Time", "China Daylight Time",
734  "Asia/Hong_Kong"
735  }, /* (UTC+08:00) Beijing, Chongqing, Hong Kong,
736  * Urumqi */
737  {
738  "Cuba Standard Time", "Cuba Daylight Time",
739  "America/Havana"
740  }, /* (UTC-05:00) Havana */
741  {
742  "Dateline Standard Time", "Dateline Daylight Time",
743  "Etc/UTC+12"
744  }, /* (UTC-12:00) International Date Line West */
745  {
746  "E. Africa Standard Time", "E. Africa Daylight Time",
747  "Africa/Nairobi"
748  }, /* (UTC+03:00) Nairobi */
749  {
750  "E. Australia Standard Time", "E. Australia Daylight Time",
751  "Australia/Brisbane"
752  }, /* (UTC+10:00) Brisbane */
753  {
754  "E. Europe Standard Time", "E. Europe Daylight Time",
755  "Europe/Bucharest"
756  }, /* (UTC+02:00) E. Europe */
757  {
758  "E. South America Standard Time", "E. South America Daylight Time",
759  "America/Araguaina"
760  }, /* (UTC-03:00) Brasilia */
761  {
762  "Eastern Standard Time", "Eastern Daylight Time",
763  "US/Eastern"
764  }, /* (UTC-05:00) Eastern Time (US & Canada) */
765  {
766  "Eastern Standard Time (Mexico)", "Eastern Daylight Time (Mexico)",
767  "America/Mexico_City"
768  }, /* (UTC-05:00) Chetumal */
769  {
770  "Easter Island Standard Time", "Easter Island Daylight Time",
771  "Pacific/Easter"
772  }, /* (UTC-06:00) Easter Island */
773  {
774  "Egypt Standard Time", "Egypt Daylight Time",
775  "Africa/Cairo"
776  }, /* (UTC+02:00) Cairo */
777  {
778  "Ekaterinburg Standard Time (RTZ 4)", "Ekaterinburg Daylight Time",
779  "Asia/Yekaterinburg"
780  }, /* (UTC+05:00) Ekaterinburg */
781  {
782  "Fiji Standard Time", "Fiji Daylight Time",
783  "Pacific/Fiji"
784  }, /* (UTC+12:00) Fiji */
785  {
786  "FLE Standard Time", "FLE Daylight Time",
787  "Europe/Helsinki"
788  }, /* (UTC+02:00) Helsinki, Kyiv, Riga, Sofia,
789  * Tallinn, Vilnius */
790  {
791  "Georgian Standard Time", "Georgian Daylight Time",
792  "Asia/Tbilisi"
793  }, /* (UTC+04:00) Tbilisi */
794  {
795  "GMT Standard Time", "GMT Daylight Time",
796  "Europe/London"
797  }, /* (UTC) Dublin, Edinburgh, Lisbon, London */
798  {
799  "Greenland Standard Time", "Greenland Daylight Time",
800  "America/Godthab"
801  }, /* (UTC-03:00) Greenland */
802  {
803  "Greenwich Standard Time", "Greenwich Daylight Time",
804  "Africa/Casablanca"
805  }, /* (UTC) Monrovia, Reykjavik */
806  {
807  "GTB Standard Time", "GTB Daylight Time",
808  "Europe/Athens"
809  }, /* (UTC+02:00) Athens, Bucharest */
810  {
811  "Haiti Standard Time", "Haiti Daylight Time",
812  "US/Eastern"
813  }, /* (UTC-05:00) Haiti */
814  {
815  "Hawaiian Standard Time", "Hawaiian Daylight Time",
816  "US/Hawaii"
817  }, /* (UTC-10:00) Hawaii */
818  {
819  "India Standard Time", "India Daylight Time",
820  "Asia/Calcutta"
821  }, /* (UTC+05:30) Chennai, Kolkata, Mumbai, New
822  * Delhi */
823  {
824  "Iran Standard Time", "Iran Daylight Time",
825  "Asia/Tehran"
826  }, /* (UTC+03:30) Tehran */
827  {
828  "Jerusalem Standard Time", "Jerusalem Daylight Time",
829  "Asia/Jerusalem"
830  }, /* (UTC+02:00) Jerusalem */
831  {
832  "Jordan Standard Time", "Jordan Daylight Time",
833  "Asia/Amman"
834  }, /* (UTC+02:00) Amman */
835  {
836  "Kamchatka Standard Time", "Kamchatka Daylight Time",
837  "Asia/Kamchatka"
838  }, /* (UTC+12:00) Petropavlovsk-Kamchatsky - Old */
839  {
840  "Korea Standard Time", "Korea Daylight Time",
841  "Asia/Seoul"
842  }, /* (UTC+09:00) Seoul */
843  {
844  "Libya Standard Time", "Libya Daylight Time",
845  "Africa/Tripoli"
846  }, /* (UTC+02:00) Tripoli */
847  {
848  "Line Islands Standard Time", "Line Islands Daylight Time",
849  "Pacific/Kiritimati"
850  }, /* (UTC+14:00) Kiritimati Island */
851  {
852  "Lord Howe Standard Time", "Lord Howe Daylight Time",
853  "Australia/Lord_Howe"
854  }, /* (UTC+10:30) Lord Howe Island */
855  {
856  "Magadan Standard Time", "Magadan Daylight Time",
857  "Asia/Magadan"
858  }, /* (UTC+10:00) Magadan */
859  {
860  "Marquesas Standard Time", "Marquesas Daylight Time",
861  "Pacific/Marquesas"
862  }, /* (UTC-09:30) Marquesas Islands */
863  {
864  "Mauritius Standard Time", "Mauritius Daylight Time",
865  "Indian/Mauritius"
866  }, /* (UTC+04:00) Port Louis */
867  {
868  "Mexico Standard Time", "Mexico Daylight Time",
869  "America/Mexico_City"
870  }, /* (UTC-06:00) Guadalajara, Mexico City,
871  * Monterrey */
872  {
873  "Mexico Standard Time 2", "Mexico Daylight Time 2",
874  "America/Chihuahua"
875  }, /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
876  {
877  "Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
878  "Atlantic/South_Georgia"
879  }, /* (UTC-02:00) Mid-Atlantic - Old */
880  {
881  "Middle East Standard Time", "Middle East Daylight Time",
882  "Asia/Beirut"
883  }, /* (UTC+02:00) Beirut */
884  {
885  "Montevideo Standard Time", "Montevideo Daylight Time",
886  "America/Montevideo"
887  }, /* (UTC-03:00) Montevideo */
888  {
889  "Morocco Standard Time", "Morocco Daylight Time",
890  "Africa/Casablanca"
891  }, /* (UTC) Casablanca */
892  {
893  "Mountain Standard Time", "Mountain Daylight Time",
894  "US/Mountain"
895  }, /* (UTC-07:00) Mountain Time (US & Canada) */
896  {
897  "Mountain Standard Time (Mexico)", "Mountain Daylight Time (Mexico)",
898  "America/Chihuahua"
899  }, /* (UTC-07:00) Chihuahua, La Paz, Mazatlan */
900  {
901  "Myanmar Standard Time", "Myanmar Daylight Time",
902  "Asia/Rangoon"
903  }, /* (UTC+06:30) Yangon (Rangoon) */
904  {
905  "N. Central Asia Standard Time", "N. Central Asia Daylight Time",
906  "Asia/Novosibirsk"
907  }, /* (UTC+06:00) Novosibirsk (RTZ 5) */
908  {
909  "Namibia Standard Time", "Namibia Daylight Time",
910  "Africa/Windhoek"
911  }, /* (UTC+01:00) Windhoek */
912  {
913  "Nepal Standard Time", "Nepal Daylight Time",
914  "Asia/Katmandu"
915  }, /* (UTC+05:45) Kathmandu */
916  {
917  "New Zealand Standard Time", "New Zealand Daylight Time",
918  "Pacific/Auckland"
919  }, /* (UTC+12:00) Auckland, Wellington */
920  {
921  "Newfoundland Standard Time", "Newfoundland Daylight Time",
922  "Canada/Newfoundland"
923  }, /* (UTC-03:30) Newfoundland */
924  {
925  "Norfolk Standard Time", "Norfolk Daylight Time",
926  "Pacific/Norfolk"
927  }, /* (UTC+11:00) Norfolk Island */
928  {
929  "North Asia East Standard Time", "North Asia East Daylight Time",
930  "Asia/Irkutsk"
931  }, /* (UTC+08:00) Irkutsk, Ulaan Bataar */
932  {
933  "North Asia Standard Time", "North Asia Daylight Time",
934  "Asia/Krasnoyarsk"
935  }, /* (UTC+07:00) Krasnoyarsk */
936  {
937  "North Korea Standard Time", "North Korea Daylight Time",
938  "Asia/Pyongyang"
939  }, /* (UTC+08:30) Pyongyang */
940  {
941  "Pacific SA Standard Time", "Pacific SA Daylight Time",
942  "America/Santiago"
943  }, /* (UTC-03:00) Santiago */
944  {
945  "Pacific Standard Time", "Pacific Daylight Time",
946  "US/Pacific"
947  }, /* (UTC-08:00) Pacific Time (US & Canada) */
948  {
949  "Pacific Standard Time (Mexico)", "Pacific Daylight Time (Mexico)",
950  "America/Tijuana"
951  }, /* (UTC-08:00) Baja California */
952  {
953  "Pakistan Standard Time", "Pakistan Daylight Time",
954  "Asia/Karachi"
955  }, /* (UTC+05:00) Islamabad, Karachi */
956  {
957  "Paraguay Standard Time", "Paraguay Daylight Time",
958  "America/Asuncion"
959  }, /* (UTC-04:00) Asuncion */
960  {
961  "Romance Standard Time", "Romance Daylight Time",
962  "Europe/Brussels"
963  }, /* (UTC+01:00) Brussels, Copenhagen, Madrid,
964  * Paris */
965  {
966  "Russia TZ 1 Standard Time", "Russia TZ 1 Daylight Time",
967  "Europe/Kaliningrad"
968  }, /* (UTC+02:00) Kaliningrad (RTZ 1) */
969  {
970  "Russia TZ 2 Standard Time", "Russia TZ 2 Daylight Time",
971  "Europe/Moscow"
972  }, /* (UTC+03:00) Moscow, St. Petersburg,
973  * Volgograd (RTZ 2) */
974  {
975  "Russia TZ 3 Standard Time", "Russia TZ 3 Daylight Time",
976  "Europe/Samara"
977  }, /* (UTC+04:00) Izhevsk, Samara (RTZ 3) */
978  {
979  "Russia TZ 4 Standard Time", "Russia TZ 4 Daylight Time",
980  "Asia/Yekaterinburg"
981  }, /* (UTC+05:00) Ekaterinburg (RTZ 4) */
982  {
983  "Russia TZ 5 Standard Time", "Russia TZ 5 Daylight Time",
984  "Asia/Novosibirsk"
985  }, /* (UTC+06:00) Novosibirsk (RTZ 5) */
986  {
987  "Russia TZ 6 Standard Time", "Russia TZ 6 Daylight Time",
988  "Asia/Krasnoyarsk"
989  }, /* (UTC+07:00) Krasnoyarsk (RTZ 6) */
990  {
991  "Russia TZ 7 Standard Time", "Russia TZ 7 Daylight Time",
992  "Asia/Irkutsk"
993  }, /* (UTC+08:00) Irkutsk (RTZ 7) */
994  {
995  "Russia TZ 8 Standard Time", "Russia TZ 8 Daylight Time",
996  "Asia/Yakutsk"
997  }, /* (UTC+09:00) Yakutsk (RTZ 8) */
998  {
999  "Russia TZ 9 Standard Time", "Russia TZ 9 Daylight Time",
1000  "Asia/Vladivostok"
1001  }, /* (UTC+10:00) Vladivostok, Magadan (RTZ 9) */
1002  {
1003  "Russia TZ 10 Standard Time", "Russia TZ 10 Daylight Time",
1004  "Asia/Magadan"
1005  }, /* (UTC+11:00) Chokurdakh (RTZ 10) */
1006  {
1007  "Russia TZ 11 Standard Time", "Russia TZ 11 Daylight Time",
1008  "Asia/Anadyr"
1009  }, /* (UTC+12:00) Anadyr,
1010  * Petropavlovsk-Kamchatsky (RTZ 11) */
1011  {
1012  "Russian Standard Time", "Russian Daylight Time",
1013  "Europe/Moscow"
1014  }, /* (UTC+03:00) Moscow, St. Petersburg,
1015  * Volgograd */
1016  {
1017  "SA Eastern Standard Time", "SA Eastern Daylight Time",
1018  "America/Buenos_Aires"
1019  }, /* (UTC-03:00) Cayenne, Fortaleza */
1020  {
1021  "SA Pacific Standard Time", "SA Pacific Daylight Time",
1022  "America/Bogota"
1023  }, /* (UTC-05:00) Bogota, Lima, Quito, Rio Branco */
1024  {
1025  "SA Western Standard Time", "SA Western Daylight Time",
1026  "America/Caracas"
1027  }, /* (UTC-04:00) Georgetown, La Paz, Manaus, San
1028  * Juan */
1029  {
1030  "Saint Pierre Standard Time", "Saint Pierre Daylight Time",
1031  "America/Miquelon"
1032  }, /* (UTC-03:00) Saint Pierre and Miquelon */
1033  {
1034  "Samoa Standard Time", "Samoa Daylight Time",
1035  "Pacific/Samoa"
1036  }, /* (UTC+13:00) Samoa */
1037  {
1038  "SE Asia Standard Time", "SE Asia Daylight Time",
1039  "Asia/Bangkok"
1040  }, /* (UTC+07:00) Bangkok, Hanoi, Jakarta */
1041  {
1042  "Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
1043  "Asia/Kuala_Lumpur"
1044  }, /* (UTC+08:00) Kuala Lumpur, Singapore */
1045  {
1046  "Sakhalin Standard Time", "Sakhalin Daylight Time",
1047  "Asia/Sakhalin"
1048  }, /* (UTC+11:00) Sakhalin */
1049  {
1050  "South Africa Standard Time", "South Africa Daylight Time",
1051  "Africa/Harare"
1052  }, /* (UTC+02:00) Harare, Pretoria */
1053  {
1054  "Sri Lanka Standard Time", "Sri Lanka Daylight Time",
1055  "Asia/Colombo"
1056  }, /* (UTC+05:30) Sri Jayawardenepura */
1057  {
1058  "Syria Standard Time", "Syria Daylight Time",
1059  "Asia/Damascus"
1060  }, /* (UTC+02:00) Damascus */
1061  {
1062  "Taipei Standard Time", "Taipei Daylight Time",
1063  "Asia/Taipei"
1064  }, /* (UTC+08:00) Taipei */
1065  {
1066  "Tasmania Standard Time", "Tasmania Daylight Time",
1067  "Australia/Hobart"
1068  }, /* (UTC+10:00) Hobart */
1069  {
1070  "Tocantins Standard Time", "Tocantins Daylight Time",
1071  "America/Araguaina"
1072  }, /* (UTC-03:00) Araguaina */
1073  {
1074  "Tokyo Standard Time", "Tokyo Daylight Time",
1075  "Asia/Tokyo"
1076  }, /* (UTC+09:00) Osaka, Sapporo, Tokyo */
1077  {
1078  "Tonga Standard Time", "Tonga Daylight Time",
1079  "Pacific/Tongatapu"
1080  }, /* (UTC+13:00) Nuku'alofa */
1081  {
1082  "Tomsk Standard Time", "Tomsk Daylight Time",
1083  "Asia/Tomsk"
1084  }, /* (UTC+07:00) Tomsk */
1085  {
1086  "Transbaikal Standard Time", "Transbaikal Daylight Time",
1087  "Asia/Chita"
1088  }, /* (UTC+09:00) Chita */
1089  {
1090  "Turkey Standard Time", "Turkey Daylight Time",
1091  "Europe/Istanbul"
1092  }, /* (UTC+02:00) Istanbul */
1093  {
1094  "Turks and Caicos Standard Time", "Turks and Caicos Daylight Time",
1095  "America/Grand_Turk"
1096  }, /* (UTC-04:00) Turks and Caicos */
1097  {
1098  "Ulaanbaatar Standard Time", "Ulaanbaatar Daylight Time",
1099  "Asia/Ulaanbaatar",
1100  }, /* (UTC+08:00) Ulaanbaatar */
1101  {
1102  "US Eastern Standard Time", "US Eastern Daylight Time",
1103  "US/Eastern"
1104  }, /* (UTC-05:00) Indiana (East) */
1105  {
1106  "US Mountain Standard Time", "US Mountain Daylight Time",
1107  "US/Arizona"
1108  }, /* (UTC-07:00) Arizona */
1109  {
1110  "Coordinated Universal Time", "Coordinated Universal Time",
1111  "UTC"
1112  }, /* (UTC) Coordinated Universal Time */
1113  {
1114  "UTC+12", "UTC+12",
1115  "Etc/GMT+12"
1116  }, /* (UTC+12:00) Coordinated Universal Time+12 */
1117  {
1118  "UTC-02", "UTC-02",
1119  "Etc/GMT-02"
1120  }, /* (UTC-02:00) Coordinated Universal Time-02 */
1121  {
1122  "UTC-08", "UTC-08",
1123  "Etc/GMT-08"
1124  }, /* (UTC-08:00) Coordinated Universal Time-08 */
1125  {
1126  "UTC-09", "UTC-09",
1127  "Etc/GMT-09"
1128  }, /* (UTC-09:00) Coordinated Universal Time-09 */
1129  {
1130  "UTC-11", "UTC-11",
1131  "Etc/GMT-11"
1132  }, /* (UTC-11:00) Coordinated Universal Time-11 */
1133  {
1134  "Venezuela Standard Time", "Venezuela Daylight Time",
1135  "America/Caracas",
1136  }, /* (UTC-04:30) Caracas */
1137  {
1138  "Vladivostok Standard Time", "Vladivostok Daylight Time",
1139  "Asia/Vladivostok"
1140  }, /* (UTC+10:00) Vladivostok (RTZ 9) */
1141  {
1142  "W. Australia Standard Time", "W. Australia Daylight Time",
1143  "Australia/Perth"
1144  }, /* (UTC+08:00) Perth */
1145 #ifdef NOT_USED
1146  /* Could not find a match for this one (just a guess). Excluded for now. */
1147  {
1148  "W. Central Africa Standard Time", "W. Central Africa Daylight Time",
1149  "WAT"
1150  }, /* (UTC+01:00) West Central Africa */
1151 #endif
1152  {
1153  "W. Europe Standard Time", "W. Europe Daylight Time",
1154  "CET"
1155  }, /* (UTC+01:00) Amsterdam, Berlin, Bern, Rome,
1156  * Stockholm, Vienna */
1157  {
1158  "W. Mongolia Standard Time", "W. Mongolia Daylight Time",
1159  "Asia/Hovd"
1160  }, /* (UTC+07:00) Hovd */
1161  {
1162  "West Asia Standard Time", "West Asia Daylight Time",
1163  "Asia/Karachi"
1164  }, /* (UTC+05:00) Ashgabat, Tashkent */
1165  {
1166  "West Bank Gaza Standard Time", "West Bank Gaza Daylight Time",
1167  "Asia/Gaza"
1168  }, /* (UTC+02:00) Gaza, Hebron */
1169  {
1170  "West Pacific Standard Time", "West Pacific Daylight Time",
1171  "Pacific/Guam"
1172  }, /* (UTC+10:00) Guam, Port Moresby */
1173  {
1174  "Yakutsk Standard Time", "Yakutsk Daylight Time",
1175  "Asia/Yakutsk"
1176  }, /* (UTC+09:00) Yakutsk */
1177  {
1178  NULL, NULL, NULL
1179  }
1180 };
1181 
1182 static const char *
1184 {
1185  int i;
1186  char tzname[128];
1187  char localtzname[256];
1188  time_t t = time(NULL);
1189  struct tm *tm = localtime(&t);
1190  HKEY rootKey;
1191  int idx;
1192 
1193  if (!tm)
1194  {
1195 #ifdef DEBUG_IDENTIFY_TIMEZONE
1196  fprintf(stderr, "could not identify system time zone: localtime() failed\n");
1197 #endif
1198  return NULL; /* go to GMT */
1199  }
1200 
1201  memset(tzname, 0, sizeof(tzname));
1202  strftime(tzname, sizeof(tzname) - 1, "%Z", tm);
1203 
1204  for (i = 0; win32_tzmap[i].stdname != NULL; i++)
1205  {
1206  if (strcmp(tzname, win32_tzmap[i].stdname) == 0 ||
1207  strcmp(tzname, win32_tzmap[i].dstname) == 0)
1208  {
1209 #ifdef DEBUG_IDENTIFY_TIMEZONE
1210  fprintf(stderr, "TZ \"%s\" matches system time zone \"%s\"\n",
1211  win32_tzmap[i].pgtzname, tzname);
1212 #endif
1213  return win32_tzmap[i].pgtzname;
1214  }
1215  }
1216 
1217  /*
1218  * Localized Windows versions return localized names for the timezone.
1219  * Scan the registry to find the English name, and then try matching
1220  * against our table again.
1221  */
1222  memset(localtzname, 0, sizeof(localtzname));
1223  if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
1224  "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
1225  0,
1226  KEY_READ,
1227  &rootKey) != ERROR_SUCCESS)
1228  {
1229 #ifdef DEBUG_IDENTIFY_TIMEZONE
1230  fprintf(stderr, "could not open registry key to identify system time zone: error code %lu\n",
1231  GetLastError());
1232 #endif
1233  return NULL; /* go to GMT */
1234  }
1235 
1236  for (idx = 0;; idx++)
1237  {
1238  char keyname[256];
1239  char zonename[256];
1240  DWORD namesize;
1241  FILETIME lastwrite;
1242  HKEY key;
1243  LONG r;
1244 
1245  memset(keyname, 0, sizeof(keyname));
1246  namesize = sizeof(keyname);
1247  if ((r = RegEnumKeyEx(rootKey,
1248  idx,
1249  keyname,
1250  &namesize,
1251  NULL,
1252  NULL,
1253  NULL,
1254  &lastwrite)) != ERROR_SUCCESS)
1255  {
1256  if (r == ERROR_NO_MORE_ITEMS)
1257  break;
1258 #ifdef DEBUG_IDENTIFY_TIMEZONE
1259  fprintf(stderr, "could not enumerate registry subkeys to identify system time zone: %d\n",
1260  (int) r);
1261 #endif
1262  break;
1263  }
1264 
1265  if ((r = RegOpenKeyEx(rootKey, keyname, 0, KEY_READ, &key)) != ERROR_SUCCESS)
1266  {
1267 #ifdef DEBUG_IDENTIFY_TIMEZONE
1268  fprintf(stderr, "could not open registry subkey to identify system time zone: %d\n",
1269  (int) r);
1270 #endif
1271  break;
1272  }
1273 
1274  memset(zonename, 0, sizeof(zonename));
1275  namesize = sizeof(zonename);
1276  if ((r = RegQueryValueEx(key, "Std", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
1277  {
1278 #ifdef DEBUG_IDENTIFY_TIMEZONE
1279  fprintf(stderr, "could not query value for key \"std\" to identify system time zone \"%s\": %d\n",
1280  keyname, (int) r);
1281 #endif
1282  RegCloseKey(key);
1283  continue; /* Proceed to look at the next timezone */
1284  }
1285  if (strcmp(tzname, zonename) == 0)
1286  {
1287  /* Matched zone */
1288  strcpy(localtzname, keyname);
1289  RegCloseKey(key);
1290  break;
1291  }
1292  memset(zonename, 0, sizeof(zonename));
1293  namesize = sizeof(zonename);
1294  if ((r = RegQueryValueEx(key, "Dlt", NULL, NULL, (unsigned char *) zonename, &namesize)) != ERROR_SUCCESS)
1295  {
1296 #ifdef DEBUG_IDENTIFY_TIMEZONE
1297  fprintf(stderr, "could not query value for key \"dlt\" to identify system time zone \"%s\": %d\n",
1298  keyname, (int) r);
1299 #endif
1300  RegCloseKey(key);
1301  continue; /* Proceed to look at the next timezone */
1302  }
1303  if (strcmp(tzname, zonename) == 0)
1304  {
1305  /* Matched DST zone */
1306  strcpy(localtzname, keyname);
1307  RegCloseKey(key);
1308  break;
1309  }
1310 
1311  RegCloseKey(key);
1312  }
1313 
1314  RegCloseKey(rootKey);
1315 
1316  if (localtzname[0])
1317  {
1318  /* Found a localized name, so scan for that one too */
1319  for (i = 0; win32_tzmap[i].stdname != NULL; i++)
1320  {
1321  if (strcmp(localtzname, win32_tzmap[i].stdname) == 0 ||
1322  strcmp(localtzname, win32_tzmap[i].dstname) == 0)
1323  {
1324 #ifdef DEBUG_IDENTIFY_TIMEZONE
1325  fprintf(stderr, "TZ \"%s\" matches localized system time zone \"%s\" (\"%s\")\n",
1326  win32_tzmap[i].pgtzname, tzname, localtzname);
1327 #endif
1328  return win32_tzmap[i].pgtzname;
1329  }
1330  }
1331  }
1332 
1333 #ifdef DEBUG_IDENTIFY_TIMEZONE
1334  fprintf(stderr, "could not find a match for system time zone \"%s\"\n",
1335  tzname);
1336 #endif
1337  return NULL; /* go to GMT */
1338 }
1339 #endif /* WIN32 */
1340 
1341 
1342 /*
1343  * Return true if the given zone name is valid and is an "acceptable" zone.
1344  */
1345 static bool
1346 validate_zone(const char *tzname)
1347 {
1348  pg_tz *tz;
1349 
1350  if (!tzname || !tzname[0])
1351  return false;
1352 
1353  tz = pg_load_tz(tzname);
1354  if (!tz)
1355  return false;
1356 
1357  if (!pg_tz_acceptable(tz))
1358  return false;
1359 
1360  return true;
1361 }
1362 
1363 /*
1364  * Identify a suitable default timezone setting based on the environment.
1365  *
1366  * The installation share_path must be passed in, as that is the default
1367  * location for the timezone database directory.
1368  *
1369  * We first look to the TZ environment variable. If not found or not
1370  * recognized by our own code, we see if we can identify the timezone
1371  * from the behavior of the system timezone library. When all else fails,
1372  * return NULL, indicating that we should default to GMT.
1373  */
1374 const char *
1376 {
1377  const char *tzname;
1378 
1379  /* Initialize timezone directory path, if needed */
1380 #ifndef SYSTEMTZDIR
1381  snprintf(tzdirpath, sizeof(tzdirpath), "%s/timezone", share_path);
1382 #endif
1383 
1384  /* Check TZ environment variable */
1385  tzname = getenv("TZ");
1386  if (validate_zone(tzname))
1387  return tzname;
1388 
1389  /* Nope, so try to identify the system timezone */
1390  tzname = identify_system_timezone();
1391  if (validate_zone(tzname))
1392  return tzname;
1393 
1394  return NULL;
1395 }
#define T_DAY
Definition: findtimezone.c:141
const char * select_default_timezone(const char *share_path)
char ** pgfnames(const char *path)
Definition: pgfnames.c:31
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:509
int tm_isdst
Definition: pgtime.h:35
int tzload(const char *name, char *canonname, struct state *sp, bool doextend)
Definition: localtime.c:556
int tm_hour
Definition: pgtime.h:29
#define TIMEZONE_GLOBAL
Definition: port.h:222
#define T_MONTH
Definition: findtimezone.c:143
time_t test_times[MAX_TEST_TIMES]
Definition: findtimezone.c:150
Datum idx(PG_FUNCTION_ARGS)
Definition: _int_op.c:264
int snprintf(char *str, size_t count, const char *fmt,...) pg_attribute_printf(3
Definition: pgtime.h:25
static pg_tz * pg_load_tz(const char *name)
Definition: findtimezone.c:90
static const char * pg_TZDIR(void)
Definition: findtimezone.c:36
#define PG_BINARY
Definition: c.h:1038
static char * share_path
Definition: initdb.c:118
static struct pg_tm tm
Definition: localtime.c:111
#define TZ_STRLEN_MAX
Definition: pgtime.h:44
#define MAXPGPATH
static bool compare_tm(struct tm *s, struct pg_tm *p)
Definition: findtimezone.c:193
int tm_mday
Definition: pgtime.h:30
int tm_mon
Definition: pgtime.h:31
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Definition: findtimezone.c:149
static int get_timezone_offset(struct tm *tm)
Definition: findtimezone.c:162
static time_t build_time_t(int year, int month, int day)
Definition: findtimezone.c:177
const char * tm_zone
Definition: pgtime.h:37
bool tzparse(const char *name, struct state *sp, bool lastditch)
Definition: localtime.c:897
#define T_WEEK
Definition: findtimezone.c:142
static int score_timezone(const char *tzname, struct tztry *tt)
Definition: findtimezone.c:220
static char tzdirpath[MAXPGPATH]
Definition: findtimezone.c:26
bool pg_tz_acceptable(pg_tz *tz)
Definition: localtime.c:1845
struct state state
Definition: pgtz.h:63
Definition: pgtz.h:59
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
#define NULL
Definition: c.h:229
void pgfnames_cleanup(char **filenames)
Definition: pgfnames.c:99
char TZname[TZ_STRLEN_MAX+1]
Definition: pgtz.h:62
struct pg_tm * pg_localtime(const pg_time_t *timep, const pg_tz *tz)
Definition: localtime.c:1314
const char * name
Definition: encode.c:521
int tm_year
Definition: pgtime.h:32
int i
const char * strerror(int errnum)
Definition: strerror.c:19
static const char * identify_system_timezone(void)
Definition: findtimezone.c:310
int pg_open_tzfile(const char *name, char *canonname)
Definition: findtimezone.c:64
int tm_yday
Definition: pgtime.h:34
int tm_sec
Definition: pgtime.h:27
int tm_min
Definition: pgtime.h:28
#define MAX_TEST_TIMES
Definition: findtimezone.c:145