granicus.if.org Git - postgresql/blob - src/timezone/pgtz.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pgtz.c
   4  *        Timezone Library Integration Functions
   5  *
   6  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
   7  *
   8  * IDENTIFICATION
   9  *        $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.33 2005/06/15 00:09:26 momjian Exp $
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #define NO_REDEFINE_TIMEFUNCS
  14
  15 #include "postgres.h"
  16
  17 #include <ctype.h>
  18 #include <sys/stat.h>
  19 #include <time.h>
  20
  21 #include "miscadmin.h"
  22 #include "pgtime.h"
  23 #include "pgtz.h"
  24 #include "storage/fd.h"
  25 #include "tzfile.h"
  26 #include "utils/datetime.h"
  27 #include "utils/elog.h"
  28 #include "utils/guc.h"
  29 #include "utils/hsearch.h"
  30
  31 /* Current global timezone */
  32 pg_tz *global_timezone = NULL;
  33
  34
  35 static char tzdir[MAXPGPATH];
  36 static int      done_tzdir = 0;
  37
  38 static const char *identify_system_timezone(void);
  39 static const char *select_default_timezone(void);
  40 static bool set_global_timezone(const char *tzname);
  41
  42
  43 /*
  44  * Return full pathname of timezone data directory
  45  */
  46 char *
  47 pg_TZDIR(void)
  48 {
  49         if (done_tzdir)
  50                 return tzdir;
  51
  52         get_share_path(my_exec_path, tzdir);
  53         strcat(tzdir, "/timezone");
  54
  55         done_tzdir = 1;
  56         return tzdir;
  57 }
  58
  59
  60 /*
  61  * The following block of code attempts to determine which timezone in our
  62  * timezone database is the best match for the active system timezone.
  63  *
  64  * On most systems, we rely on trying to match the observable behavior of
  65  * the C library's localtime() function.  The database zone that matches
  66  * furthest into the past is the one to use.  Often there will be several
  67  * zones with identical rankings (since the zic database assigns multiple
  68  * names to many zones).  We break ties arbitrarily by preferring shorter,
  69  * then alphabetically earlier zone names.
  70  *
  71  * Win32's native knowledge about timezones appears to be too incomplete
  72  * and too different from the zic database for the above matching strategy
  73  * to be of any use. But there is just a limited number of timezones
  74  * available, so we can rely on a handmade mapping table instead.
  75  */
  76
  77 #ifndef WIN32
  78
  79 #define T_DAY   ((time_t) (60*60*24))
  80 #define T_WEEK  ((time_t) (60*60*24*7))
  81 #define T_MONTH ((time_t) (60*60*24*31))
  82
  83 #define MAX_TEST_TIMES (52*100) /* 100 years, or 1904..2004 */
  84
  85 struct tztry
  86 {
  87         int                     n_test_times;
  88         time_t          test_times[MAX_TEST_TIMES];
  89 };
  90
  91 static void scan_available_timezones(char *tzdir, char *tzdirsub,
  92                                                  struct tztry * tt,
  93                                                  int *bestscore, char *bestzonename);
  94
  95
  96 /*
  97  * Get GMT offset from a system struct tm
  98  */
  99 static int
 100 get_timezone_offset(struct tm * tm)
 101 {
 102 #if defined(HAVE_STRUCT_TM_TM_ZONE)
 103         return tm->tm_gmtoff;
 104 #elif defined(HAVE_INT_TIMEZONE)
 105         return -TIMEZONE_GLOBAL;
 106 #else
 107 #error No way to determine TZ? Can this happen?
 108 #endif
 109 }
 110
 111 /*
 112  * Convenience subroutine to convert y/m/d to time_t (NOT pg_time_t)
 113  */
 114 static time_t
 115 build_time_t(int year, int month, int day)
 116 {
 117         struct tm       tm;
 118
 119         memset(&tm, 0, sizeof(tm));
 120         tm.tm_mday = day;
 121         tm.tm_mon = month - 1;
 122         tm.tm_year = year - 1900;
 123
 124         return mktime(&tm);
 125 }
 126
 127 /*
 128  * Does a system tm value match one we computed ourselves?
 129  */
 130 static bool
 131 compare_tm(struct tm * s, struct pg_tm * p)
 132 {
 133         if (s->tm_sec != p->tm_sec ||
 134                 s->tm_min != p->tm_min ||
 135                 s->tm_hour != p->tm_hour ||
 136                 s->tm_mday != p->tm_mday ||
 137                 s->tm_mon != p->tm_mon ||
 138                 s->tm_year != p->tm_year ||
 139                 s->tm_wday != p->tm_wday ||
 140                 s->tm_yday != p->tm_yday ||
 141                 s->tm_isdst != p->tm_isdst)
 142                 return false;
 143         return true;
 144 }
 145
 146 /*
 147  * See how well a specific timezone setting matches the system behavior
 148  *
 149  * We score a timezone setting according to the number of test times it
 150  * matches.  (The test times are ordered later-to-earlier, but this routine
 151  * doesn't actually know that; it just scans until the first non-match.)
 152  *
 153  * We return -1 for a completely unusable setting; this is worse than the
 154  * score of zero for a setting that works but matches not even the first
 155  * test time.
 156  */
 157 static int
 158 score_timezone(const char *tzname, struct tztry * tt)
 159 {
 160         int                     i;
 161         pg_time_t       pgtt;
 162         struct tm  *systm;
 163         struct pg_tm *pgtm;
 164         char            cbuf[TZ_STRLEN_MAX + 1];
 165         pg_tz       tz;
 166
 167
 168         /* Load timezone directly. Don't use pg_tzset, because we don't want
 169          * all timezones loaded in the cache at startup. */
 170         if (tzload(tzname, &tz.state) != 0) {
 171                 if (tzname[0] == ':' || tzparse(tzname, &tz.state, FALSE) != 0) {
 172                         return -1;          /* can't handle the TZ name at all */
 173                 }
 174         }
 175
 176         /* Reject if leap seconds involved */
 177         if (!tz_acceptable(&tz))
 178         {
 179                 elog(DEBUG4, "Reject TZ \"%s\": uses leap seconds", tzname);
 180                 return -1;
 181         }
 182
 183         /* Check for match at all the test times */
 184         for (i = 0; i < tt->n_test_times; i++)
 185         {
 186                 pgtt = (pg_time_t) (tt->test_times[i]);
 187                 pgtm = pg_localtime(&pgtt, &tz);
 188                 if (!pgtm)
 189                         return -1;                      /* probably shouldn't happen */
 190                 systm = localtime(&(tt->test_times[i]));
 191                 if (!systm)
 192                 {
 193                         elog(DEBUG4, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s, system had no data",
 194                                  tzname, i, (long) pgtt,
 195                                  pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
 196                                  pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
 197                                  pgtm->tm_isdst ? "dst" : "std");
 198                         return i;
 199                 }
 200                 if (!compare_tm(systm, pgtm))
 201                 {
 202                         elog(DEBUG4, "TZ \"%s\" scores %d: at %ld %04d-%02d-%02d %02d:%02d:%02d %s versus %04d-%02d-%02d %02d:%02d:%02d %s",
 203                                  tzname, i, (long) pgtt,
 204                                  pgtm->tm_year + 1900, pgtm->tm_mon + 1, pgtm->tm_mday,
 205                                  pgtm->tm_hour, pgtm->tm_min, pgtm->tm_sec,
 206                                  pgtm->tm_isdst ? "dst" : "std",
 207                                  systm->tm_year + 1900, systm->tm_mon + 1, systm->tm_mday,
 208                                  systm->tm_hour, systm->tm_min, systm->tm_sec,
 209                                  systm->tm_isdst ? "dst" : "std");
 210                         return i;
 211                 }
 212                 if (systm->tm_isdst >= 0)
 213                 {
 214                         /* Check match of zone names, too */
 215                         if (pgtm->tm_zone == NULL)
 216                                 return -1;              /* probably shouldn't happen */
 217                         memset(cbuf, 0, sizeof(cbuf));
 218                         strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm);          /* zone abbr */
 219                         if (strcmp(cbuf, pgtm->tm_zone) != 0)
 220                         {
 221                                 elog(DEBUG4, "TZ \"%s\" scores %d: at %ld \"%s\" versus \"%s\"",
 222                                          tzname, i, (long) pgtt,
 223                                          pgtm->tm_zone, cbuf);
 224                                 return i;
 225                         }
 226                 }
 227         }
 228
 229         elog(DEBUG4, "TZ \"%s\" gets max score %d", tzname, i);
 230         return i;
 231 }
 232
 233
 234 /*
 235  * Try to identify a timezone name (in our terminology) that best matches the
 236  * observed behavior of the system timezone library.  We cannot assume that
 237  * the system TZ environment setting (if indeed there is one) matches our
 238  * terminology, so we ignore it and just look at what localtime() returns.
 239  */
 240 static const char *
 241 identify_system_timezone(void)
 242 {
 243         static char resultbuf[TZ_STRLEN_MAX + 1];
 244         time_t          tnow;
 245         time_t          t;
 246         struct tztry tt;
 247         struct tm  *tm;
 248         int                     bestscore;
 249         char            tmptzdir[MAXPGPATH];
 250         int                     std_ofs;
 251         char            std_zone_name[TZ_STRLEN_MAX + 1],
 252                                 dst_zone_name[TZ_STRLEN_MAX + 1];
 253         char            cbuf[TZ_STRLEN_MAX + 1];
 254
 255         /* Initialize OS timezone library */
 256         tzset();
 257
 258         /*
 259          * Set up the list of dates to be probed to see how well our timezone
 260          * matches the system zone.  We first probe January and July of 2004;
 261          * this serves to quickly eliminate the vast majority of the TZ
 262          * database entries.  If those dates match, we probe every week from
 263          * 2004 backwards to late 1904.  (Weekly resolution is good enough to
 264          * identify DST transition rules, since everybody switches on
 265          * Sundays.)  The further back the zone matches, the better we score
 266          * it.  This may seem like a rather random way of doing things, but
 267          * experience has shown that system-supplied timezone definitions are
 268          * likely to have DST behavior that is right for the recent past and
 269          * not so accurate further back. Scoring in this way allows us to
 270          * recognize zones that have some commonality with the zic database,
 271          * without insisting on exact match. (Note: we probe Thursdays, not
 272          * Sundays, to avoid triggering DST-transition bugs in localtime
 273          * itself.)
 274          */
 275         tt.n_test_times = 0;
 276         tt.test_times[tt.n_test_times++] = build_time_t(2004, 1, 15);
 277         tt.test_times[tt.n_test_times++] = t = build_time_t(2004, 7, 15);
 278         while (tt.n_test_times < MAX_TEST_TIMES)
 279         {
 280                 t -= T_WEEK;
 281                 tt.test_times[tt.n_test_times++] = t;
 282         }
 283
 284         /* Search for the best-matching timezone file */
 285         strcpy(tmptzdir, pg_TZDIR());
 286         bestscore = -1;
 287         resultbuf[0] = '\0';
 288         scan_available_timezones(tmptzdir, tmptzdir + strlen(tmptzdir) + 1,
 289                                                          &tt,
 290                                                          &bestscore, resultbuf);
 291         if (bestscore > 0)
 292                 return resultbuf;
 293
 294         /*
 295          * Couldn't find a match in the database, so next we try constructed
 296          * zone names (like "PST8PDT").
 297          *
 298          * First we need to determine the names of the local standard and
 299          * daylight zones.      The idea here is to scan forward from today until
 300          * we have seen both zones, if both are in use.
 301          */
 302         memset(std_zone_name, 0, sizeof(std_zone_name));
 303         memset(dst_zone_name, 0, sizeof(dst_zone_name));
 304         std_ofs = 0;
 305
 306         tnow = time(NULL);
 307
 308         /*
 309          * Round back to a GMT midnight so results don't depend on local time
 310          * of day
 311          */
 312         tnow -= (tnow % T_DAY);
 313
 314         /*
 315          * We have to look a little further ahead than one year, in case today
 316          * is just past a DST boundary that falls earlier in the year than the
 317          * next similar boundary.  Arbitrarily scan up to 14 months.
 318          */
 319         for (t = tnow; t <= tnow + T_MONTH * 14; t += T_MONTH)
 320         {
 321                 tm = localtime(&t);
 322                 if (!tm)
 323                         continue;
 324                 if (tm->tm_isdst < 0)
 325                         continue;
 326                 if (tm->tm_isdst == 0 && std_zone_name[0] == '\0')
 327                 {
 328                         /* found STD zone */
 329                         memset(cbuf, 0, sizeof(cbuf));
 330                         strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
 331                         strcpy(std_zone_name, cbuf);
 332                         std_ofs = get_timezone_offset(tm);
 333                 }
 334                 if (tm->tm_isdst > 0 && dst_zone_name[0] == '\0')
 335                 {
 336                         /* found DST zone */
 337                         memset(cbuf, 0, sizeof(cbuf));
 338                         strftime(cbuf, sizeof(cbuf) - 1, "%Z", tm); /* zone abbr */
 339                         strcpy(dst_zone_name, cbuf);
 340                 }
 341                 /* Done if found both */
 342                 if (std_zone_name[0] && dst_zone_name[0])
 343                         break;
 344         }
 345
 346         /* We should have found a STD zone name by now... */
 347         if (std_zone_name[0] == '\0')
 348         {
 349                 ereport(LOG,
 350                                 (errmsg("unable to determine system timezone, defaulting to \"%s\"", "GMT"),
 351                                  errhint("You can specify the correct timezone in postgresql.conf.")));
 352                 return NULL;                    /* go to GMT */
 353         }
 354
 355         /* If we found DST then try STD<ofs>DST */
 356         if (dst_zone_name[0] != '\0')
 357         {
 358                 snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
 359                                  std_zone_name, -std_ofs / 3600, dst_zone_name);
 360                 if (score_timezone(resultbuf, &tt) > 0)
 361                         return resultbuf;
 362         }
 363
 364         /* Try just the STD timezone (works for GMT at least) */
 365         strcpy(resultbuf, std_zone_name);
 366         if (score_timezone(resultbuf, &tt) > 0)
 367                 return resultbuf;
 368
 369         /* Try STD<ofs> */
 370         snprintf(resultbuf, sizeof(resultbuf), "%s%d",
 371                          std_zone_name, -std_ofs / 3600);
 372         if (score_timezone(resultbuf, &tt) > 0)
 373                 return resultbuf;
 374
 375         /*
 376          * Did not find the timezone.  Fallback to use a GMT zone.      Note that
 377          * the zic timezone database names the GMT-offset zones in POSIX
 378          * style: plus is west of Greenwich.  It's unfortunate that this is
 379          * opposite of SQL conventions.  Should we therefore change the names?
 380          * Probably not...
 381          */
 382         snprintf(resultbuf, sizeof(resultbuf), "Etc/GMT%s%d",
 383                          (-std_ofs > 0) ? "+" : "", -std_ofs / 3600);
 384
 385         ereport(LOG,
 386          (errmsg("could not recognize system timezone, defaulting to \"%s\"",
 387                          resultbuf),
 388         errhint("You can specify the correct timezone in postgresql.conf.")));
 389         return resultbuf;
 390 }
 391
 392 /*
 393  * Recursively scan the timezone database looking for the best match to
 394  * the system timezone behavior.
 395  *
 396  * tzdir points to a buffer of size MAXPGPATH.  On entry, it holds the
 397  * pathname of a directory containing TZ files.  We internally modify it
 398  * to hold pathnames of sub-directories and files, but must restore it
 399  * to its original contents before exit.
 400  *
 401  * tzdirsub points to the part of tzdir that represents the subfile name
 402  * (ie, tzdir + the original directory name length, plus one for the
 403  * first added '/').
 404  *
 405  * tt tells about the system timezone behavior we need to match.
 406  *
 407  * *bestscore and *bestzonename on entry hold the best score found so far
 408  * and the name of the best zone.  We overwrite them if we find a better
 409  * score.  bestzonename must be a buffer of length TZ_STRLEN_MAX + 1.
 410  */
 411 static void
 412 scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry * tt,
 413                                                  int *bestscore, char *bestzonename)
 414 {
 415         int                     tzdir_orig_len = strlen(tzdir);
 416         DIR                *dirdesc;
 417
 418         dirdesc = AllocateDir(tzdir);
 419         if (!dirdesc)
 420         {
 421                 ereport(LOG,
 422                                 (errcode_for_file_access(),
 423                                  errmsg("could not open directory \"%s\": %m", tzdir)));
 424                 return;
 425         }
 426
 427         for (;;)
 428         {
 429                 struct dirent *direntry;
 430                 struct stat statbuf;
 431
 432                 errno = 0;
 433                 direntry = readdir(dirdesc);
 434                 if (!direntry)
 435                 {
 436                         if (errno)
 437                                 ereport(LOG,
 438                                                 (errcode_for_file_access(),
 439                                                  errmsg("error reading directory: %m")));
 440                         break;
 441                 }
 442
 443                 /* Ignore . and .., plus any other "hidden" files */
 444                 if (direntry->d_name[0] == '.')
 445                         continue;
 446
 447                 snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
 448                                  "/%s", direntry->d_name);
 449
 450                 if (stat(tzdir, &statbuf) != 0)
 451                 {
 452                         ereport(LOG,
 453                                         (errcode_for_file_access(),
 454                                          errmsg("could not stat \"%s\": %m", tzdir)));
 455                         continue;
 456                 }
 457
 458                 if (S_ISDIR(statbuf.st_mode))
 459                 {
 460                         /* Recurse into subdirectory */
 461                         scan_available_timezones(tzdir, tzdirsub, tt,
 462                                                                          bestscore, bestzonename);
 463                 }
 464                 else
 465                 {
 466                         /* Load and test this file */
 467                         int                     score = score_timezone(tzdirsub, tt);
 468
 469                         if (score > *bestscore)
 470                         {
 471                                 *bestscore = score;
 472                                 StrNCpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
 473                         }
 474                         else if (score == *bestscore)
 475                         {
 476                                 /* Consider how to break a tie */
 477                                 if (strlen(tzdirsub) < strlen(bestzonename) ||
 478                                         (strlen(tzdirsub) == strlen(bestzonename) &&
 479                                          strcmp(tzdirsub, bestzonename) < 0))
 480                                         StrNCpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1);
 481                         }
 482                 }
 483         }
 484
 485         FreeDir(dirdesc);
 486
 487         /* Restore tzdir */
 488         tzdir[tzdir_orig_len] = '\0';
 489 }
 490
 491 #else                                                   /* WIN32 */
 492
 493 static const struct
 494 {
 495         const char *stdname;            /* Windows name of standard timezone */
 496         const char *dstname;            /* Windows name of daylight timezone */
 497         const char *pgtzname;           /* Name of pgsql timezone to map to */
 498 }       win32_tzmap[] =
 499
 500 {
 501         /*
 502          * This list was built from the contents of the registry at
 503          * HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
 504          * NT\CurrentVersion\Time Zones on Windows XP Professional SP1
 505          *
 506          * The zones have been matched to zic timezones by looking at the cities
 507          * listed in the win32 display name (in the comment here) in most
 508          * cases.
 509          */
 510         {
 511                 "Afghanistan Standard Time", "Afghanistan Daylight Time",
 512                 "Asia/Kabul"
 513         },                                                      /* (GMT+04:30) Kabul */
 514         {
 515                 "Alaskan Standard Time", "Alaskan Daylight Time",
 516                 "US/Alaska"
 517         },                                                      /* (GMT-09:00) Alaska */
 518         {
 519                 "Arab Standard Time", "Arab Daylight Time",
 520                 "Asia/Kuwait"
 521         },                                                      /* (GMT+03:00) Kuwait, Riyadh */
 522         {
 523                 "Arabian Standard Time", "Arabian Daylight Time",
 524                 "Asia/Muscat"
 525         },                                                      /* (GMT+04:00) Abu Dhabi, Muscat */
 526         {
 527                 "Arabic Standard Time", "Arabic Daylight Time",
 528                 "Asia/Baghdad"
 529         },                                                      /* (GMT+03:00) Baghdad */
 530         {
 531                 "Atlantic Standard Time", "Atlantic Daylight Time",
 532                 "Canada/Atlantic"
 533         },                                                      /* (GMT-04:00) Atlantic Time (Canada) */
 534         {
 535                 "AUS Central Standard Time", "AUS Central Daylight Time",
 536                 "Australia/Darwin"
 537         },                                                      /* (GMT+09:30) Darwin */
 538         {
 539                 "AUS Eastern Standard Time", "AUS Eastern Daylight Time",
 540                 "Australia/Canberra"
 541         },                                                      /* (GMT+10:00) Canberra, Melbourne, Sydney */
 542         {
 543                 "Azores Standard Time", "Azores Daylight Time",
 544                 "Atlantic/Azores"
 545         },                                                      /* (GMT-01:00) Azores */
 546         {
 547                 "Canada Central Standard Time", "Canada Central Daylight Time",
 548                 "Canada/Saskatchewan"
 549         },                                                      /* (GMT-06:00) Saskatchewan */
 550         {
 551                 "Cape Verde Standard Time", "Cape Verde Daylight Time",
 552                 "Atlantic/Cape_Verde"
 553         },                                                      /* (GMT-01:00) Cape Verde Is. */
 554         {
 555                 "Caucasus Standard Time", "Caucasus Daylight Time",
 556                 "Asia/Baku"
 557         },                                                      /* (GMT+04:00) Baku, Tbilisi, Yerevan */
 558         {
 559                 "Cen. Australia Standard Time", "Cen. Australia Daylight Time",
 560                 "Australia/Adelaide"
 561         },                                                      /* (GMT+09:30) Adelaide */
 562         {
 563                 "Central America Standard Time", "Central America Daylight Time",
 564                 "CST6CDT"
 565         },                                                      /* (GMT-06:00) Central America */
 566         {
 567                 "Central Asia Standard Time", "Central Asia Daylight Time",
 568                 "Asia/Dhaka"
 569         },                                                      /* (GMT+06:00) Astana, Dhaka */
 570         {
 571                 "Central Europe Standard Time", "Central Europe Daylight Time",
 572                 "Europe/Belgrade"
 573         },                                                      /* (GMT+01:00) Belgrade, Bratislava,
 574                                                                  * Budapest, Ljubljana, Prague */
 575         {
 576                 "Central European Standard Time", "Central European Daylight Time",
 577                 "Europe/Sarajevo"
 578         },                                                      /* (GMT+01:00) Sarajevo, Skopje, Warsaw,
 579                                                                  * Zagreb */
 580         {
 581                 "Central Pacific Standard Time", "Central Pacific Daylight Time",
 582                 "Pacific/Noumea"
 583         },                                                      /* (GMT+11:00) Magadan, Solomon Is., New
 584                                                                  * Caledonia */
 585         {
 586                 "Central Standard Time", "Central Daylight Time",
 587                 "US/Central"
 588         },                                                      /* (GMT-06:00) Central Time (US & Canada) */
 589         {
 590                 "China Standard Time", "China Daylight Time",
 591                 "Asia/Hong_Kong"
 592         },                                                      /* (GMT+08:00) Beijing, Chongqing, Hong
 593                                                                  * Kong, Urumqi */
 594         {
 595                 "Dateline Standard Time", "Dateline Daylight Time",
 596                 "Etc/GMT+12"
 597         },                                                      /* (GMT-12:00) International Date Line
 598                                                                  * West */
 599         {
 600                 "E. Africa Standard Time", "E. Africa Daylight Time",
 601                 "Africa/Nairobi"
 602         },                                                      /* (GMT+03:00) Nairobi */
 603         {
 604                 "E. Australia Standard Time", "E. Australia Daylight Time",
 605                 "Australia/Brisbane"
 606         },                                                      /* (GMT+10:00) Brisbane */
 607         {
 608                 "E. Europe Standard Time", "E. Europe Daylight Time",
 609                 "Europe/Bucharest"
 610         },                                                      /* (GMT+02:00) Bucharest */
 611         {
 612                 "E. South America Standard Time", "E. South America Daylight Time",
 613                 "America/Araguaina"
 614         },                                                      /* (GMT-03:00) Brasilia */
 615         {
 616                 "Eastern Standard Time", "Eastern Daylight Time",
 617                 "US/Eastern"
 618         },                                                      /* (GMT-05:00) Eastern Time (US & Canada) */
 619         {
 620                 "Egypt Standard Time", "Egypt Daylight Time",
 621                 "Africa/Cairo"
 622         },                                                      /* (GMT+02:00) Cairo */
 623         {
 624                 "Ekaterinburg Standard Time", "Ekaterinburg Daylight Time",
 625                 "Asia/Yekaterinburg"
 626         },                                                      /* (GMT+05:00) Ekaterinburg */
 627         {
 628                 "Fiji Standard Time", "Fiji Daylight Time",
 629                 "Pacific/Fiji"
 630         },                                                      /* (GMT+12:00) Fiji, Kamchatka, Marshall
 631                                                                  * Is. */
 632         {
 633                 "FLE Standard Time", "FLE Daylight Time",
 634                 "Europe/Helsinki"
 635         },                                                      /* (GMT+02:00) Helsinki, Kyiv, Riga,
 636                                                                  * Sofia, Tallinn, Vilnius */
 637         {
 638                 "GMT Standard Time", "GMT Daylight Time",
 639                 "Europe/Dublin"
 640         },                                                      /* (GMT) Greenwich Mean Time : Dublin,
 641                                                                  * Edinburgh, Lisbon, London */
 642         {
 643                 "Greenland Standard Time", "Greenland Daylight Time",
 644                 "America/Godthab"
 645         },                                                      /* (GMT-03:00) Greenland */
 646         {
 647                 "Greenwich Standard Time", "Greenwich Daylight Time",
 648                 "Africa/Casablanca"
 649         },                                                      /* (GMT) Casablanca, Monrovia */
 650         {
 651                 "GTB Standard Time", "GTB Daylight Time",
 652                 "Europe/Athens"
 653         },                                                      /* (GMT+02:00) Athens, Istanbul, Minsk */
 654         {
 655                 "Hawaiian Standard Time", "Hawaiian Daylight Time",
 656                 "US/Hawaii"
 657         },                                                      /* (GMT-10:00) Hawaii */
 658         {
 659                 "India Standard Time", "India Daylight Time",
 660                 "Asia/Calcutta"
 661         },                                                      /* (GMT+05:30) Chennai, Kolkata, Mumbai,
 662                                                                  * New Delhi */
 663         {
 664                 "Iran Standard Time", "Iran Daylight Time",
 665                 "Asia/Tehran"
 666         },                                                      /* (GMT+03:30) Tehran */
 667         {
 668                 "Jerusalem Standard Time", "Jerusalem Daylight Time",
 669                 "Asia/Jerusalem"
 670         },                                                      /* (GMT+02:00) Jerusalem */
 671         {
 672                 "Korea Standard Time", "Korea Daylight Time",
 673                 "Asia/Seoul"
 674         },                                                      /* (GMT+09:00) Seoul */
 675         {
 676                 "Mexico Standard Time", "Mexico Daylight Time",
 677                 "America/Mexico_City"
 678         },                                                      /* (GMT-06:00) Guadalajara, Mexico City,
 679                                                                  * Monterrey */
 680         {
 681                 "Mexico Standard Time", "Mexico Daylight Time",
 682                 "America/La_Paz"
 683         },                                                      /* (GMT-07:00) Chihuahua, La Paz, Mazatlan */
 684         {
 685                 "Mid-Atlantic Standard Time", "Mid-Atlantic Daylight Time",
 686                 "Atlantic/South_Georgia"
 687         },                                                      /* (GMT-02:00) Mid-Atlantic */
 688         {
 689                 "Mountain Standard Time", "Mountain Daylight Time",
 690                 "US/Mountain"
 691         },                                                      /* (GMT-07:00) Mountain Time (US & Canada) */
 692         {
 693                 "Myanmar Standard Time", "Myanmar Daylight Time",
 694                 "Asia/Rangoon"
 695         },                                                      /* (GMT+06:30) Rangoon */
 696         {
 697                 "N. Central Asia Standard Time", "N. Central Asia Daylight Time",
 698                 "Asia/Almaty"
 699         },                                                      /* (GMT+06:00) Almaty, Novosibirsk */
 700         {
 701                 "Nepal Standard Time", "Nepal Daylight Time",
 702                 "Asia/Katmandu"
 703         },                                                      /* (GMT+05:45) Kathmandu */
 704         {
 705                 "New Zealand Standard Time", "New Zealand Daylight Time",
 706                 "Pacific/Auckland"
 707         },                                                      /* (GMT+12:00) Auckland, Wellington */
 708         {
 709                 "Newfoundland Standard Time", "Newfoundland Daylight Time",
 710                 "Canada/Newfoundland"
 711         },                                                      /* (GMT-03:30) Newfoundland */
 712         {
 713                 "North Asia East Standard Time", "North Asia East Daylight Time",
 714                 "Asia/Irkutsk"
 715         },                                                      /* (GMT+08:00) Irkutsk, Ulaan Bataar */
 716         {
 717                 "North Asia Standard Time", "North Asia Daylight Time",
 718                 "Asia/Krasnoyarsk"
 719         },                                                      /* (GMT+07:00) Krasnoyarsk */
 720         {
 721                 "Pacific SA Standard Time", "Pacific SA Daylight Time",
 722                 "America/Santiago"
 723         },                                                      /* (GMT-04:00) Santiago */
 724         {
 725                 "Pacific Standard Time", "Pacific Daylight Time",
 726                 "US/Pacific"
 727         },                                                      /* (GMT-08:00) Pacific Time (US & Canada);
 728                                                                  * Tijuana */
 729         {
 730                 "Romance Standard Time", "Romance Daylight Time",
 731                 "Europe/Brussels"
 732         },                                                      /* (GMT+01:00) Brussels, Copenhagen,
 733                                                                  * Madrid, Paris */
 734         {
 735                 "Russian Standard Time", "Russian Daylight Time",
 736                 "Europe/Moscow"
 737         },                                                      /* (GMT+03:00) Moscow, St. Petersburg,
 738                                                                  * Volgograd */
 739         {
 740                 "SA Eastern Standard Time", "SA Eastern Daylight Time",
 741                 "America/Buenos_Aires"
 742         },                                                      /* (GMT-03:00) Buenos Aires, Georgetown */
 743         {
 744                 "SA Pacific Standard Time", "SA Pacific Daylight Time",
 745                 "America/Bogota"
 746         },                                                      /* (GMT-05:00) Bogota, Lima, Quito */
 747         {
 748                 "SA Western Standard Time", "SA Western Daylight Time",
 749                 "America/Caracas"
 750         },                                                      /* (GMT-04:00) Caracas, La Paz */
 751         {
 752                 "Samoa Standard Time", "Samoa Daylight Time",
 753                 "Pacific/Midway"
 754         },                                                      /* (GMT-11:00) Midway Island, Samoa */
 755         {
 756                 "SE Asia Standard Time", "SE Asia Daylight Time",
 757                 "Asia/Bangkok"
 758         },                                                      /* (GMT+07:00) Bangkok, Hanoi, Jakarta */
 759         {
 760                 "Malay Peninsula Standard Time", "Malay Peninsula Daylight Time",
 761                 "Asia/Kuala_Lumpur"
 762         },                                                      /* (GMT+08:00) Kuala Lumpur, Singapore */
 763         {
 764                 "South Africa Standard Time", "South Africa Daylight Time",
 765                 "Africa/Harare"
 766         },                                                      /* (GMT+02:00) Harare, Pretoria */
 767         {
 768                 "Sri Lanka Standard Time", "Sri Lanka Daylight Time",
 769                 "Asia/Colombo"
 770         },                                                      /* (GMT+06:00) Sri Jayawardenepura */
 771         {
 772                 "Taipei Standard Time", "Taipei Daylight Time",
 773                 "Asia/Taipei"
 774         },                                                      /* (GMT+08:00) Taipei */
 775         {
 776                 "Tasmania Standard Time", "Tasmania Daylight Time",
 777                 "Australia/Hobart"
 778         },                                                      /* (GMT+10:00) Hobart */
 779         {
 780                 "Tokyo Standard Time", "Tokyo Daylight Time",
 781                 "Asia/Tokyo"
 782         },                                                      /* (GMT+09:00) Osaka, Sapporo, Tokyo */
 783         {
 784                 "Tonga Standard Time", "Tonga Daylight Time",
 785                 "Pacific/Tongatapu"
 786         },                                                      /* (GMT+13:00) Nuku'alofa */
 787         {
 788                 "US Eastern Standard Time", "US Eastern Daylight Time",
 789                 "US/Eastern"
 790         },                                                      /* (GMT-05:00) Indiana (East) */
 791         {
 792                 "US Mountain Standard Time", "US Mountain Daylight Time",
 793                 "US/Arizona"
 794         },                                                      /* (GMT-07:00) Arizona */
 795         {
 796                 "Vladivostok Standard Time", "Vladivostok Daylight Time",
 797                 "Asia/Vladivostok"
 798         },                                                      /* (GMT+10:00) Vladivostok */
 799         {
 800                 "W. Australia Standard Time", "W. Australia Daylight Time",
 801                 "Australia/Perth"
 802         },                                                      /* (GMT+08:00) Perth */
 803 /*      {"W. Central Africa Standard Time", "W. Central Africa Daylight Time",
 804          *       *      ""}, Could not find a match for this one. Excluded for now. *//* (
 805          * G MT+01:00) West Central Africa */
 806         {
 807                 "W. Europe Standard Time", "W. Europe Daylight Time",
 808                 "CET"
 809         },                                                      /* (GMT+01:00) Amsterdam, Berlin, Bern,
 810                                                                  * Rome, Stockholm, Vienna */
 811         {
 812                 "West Asia Standard Time", "West Asia Daylight Time",
 813                 "Asia/Karachi"
 814         },                                                      /* (GMT+05:00) Islamabad, Karachi,
 815                                                                  * Tashkent */
 816         {
 817                 "West Pacific Standard Time", "West Pacific Daylight Time",
 818                 "Pacific/Guam"
 819         },                                                      /* (GMT+10:00) Guam, Port Moresby */
 820         {
 821                 "Yakutsk Standard Time", "Yakutsk Daylight Time",
 822                 "Asia/Yakutsk"
 823         },                                                      /* (GMT+09:00) Yakutsk */
 824         {
 825                 NULL, NULL, NULL
 826         }
 827 };
 828
 829 static const char *
 830 identify_system_timezone(void)
 831 {
 832         int                     i;
 833         char            tzname[128];
 834         char        localtzname[256];
 835         time_t          t = time(NULL);
 836         struct tm  *tm = localtime(&t);
 837         HKEY        rootKey;
 838         int         idx;
 839
 840         if (!tm)
 841         {
 842                 ereport(WARNING,
 843                                 (errmsg_internal("could not determine current date/time: localtime failed")));
 844                 return NULL;
 845         }
 846
 847         memset(tzname, 0, sizeof(tzname));
 848         strftime(tzname, sizeof(tzname) - 1, "%Z", tm);
 849
 850         for (i = 0; win32_tzmap[i].stdname != NULL; i++)
 851         {
 852                 if (strcmp(tzname, win32_tzmap[i].stdname) == 0 ||
 853                         strcmp(tzname, win32_tzmap[i].dstname) == 0)
 854                 {
 855                         elog(DEBUG4, "TZ \"%s\" matches Windows timezone \"%s\"",
 856                                  win32_tzmap[i].pgtzname, tzname);
 857                         return win32_tzmap[i].pgtzname;
 858                 }
 859         }
 860
 861         /*
 862          * Localized Windows versions return localized names for the
 863          * timezone. Scan the registry to find the English name,
 864          * and then try matching against our table again.
 865          */
 866         memset(localtzname, 0, sizeof(localtzname));
 867         if (RegOpenKeyEx(HKEY_LOCAL_MACHINE,
 868                                          "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones",
 869                                          0,
 870                                          KEY_READ,
 871                                          &rootKey) != ERROR_SUCCESS)
 872         {
 873                 ereport(WARNING,
 874                                 (errmsg_internal("could not open registry key to identify Windows timezone: %i", (int)GetLastError())));
 875                 return NULL;
 876         }
 877
 878         for (idx = 0; ; idx++)
 879         {
 880                 char keyname[256];
 881                 char zonename[256];
 882                 DWORD namesize;
 883                 FILETIME lastwrite;
 884                 HKEY key;
 885                 LONG r;
 886
 887                 memset(keyname, 0, sizeof(keyname));
 888                 namesize = sizeof(keyname);
 889                 if ((r=RegEnumKeyEx(rootKey,
 890                                                         idx,
 891                                                         keyname,
 892                                                         &namesize,
 893                                                         NULL,
 894                                                         NULL,
 895                                                         NULL,
 896                                                         &lastwrite)) != ERROR_SUCCESS)
 897                 {
 898                         if (r == ERROR_NO_MORE_ITEMS)
 899                                 break;
 900                         ereport(WARNING,
 901                                         (errmsg_internal("could not enumerate registry subkeys to identify Windows timezone: %i", (int)r)));
 902                         break;
 903                 }
 904
 905                 if ((r=RegOpenKeyEx(rootKey,keyname,0,KEY_READ,&key)) != ERROR_SUCCESS)
 906                 {
 907                         ereport(WARNING,
 908                                         (errmsg_internal("could not open registry subkey to identify Windows timezone: %i", (int)r)));
 909                         break;
 910                 }
 911
 912                 memset(zonename, 0, sizeof(zonename));
 913                 namesize = sizeof(zonename);
 914                 if ((r=RegQueryValueEx(key, "Std", NULL, NULL, zonename, &namesize)) != ERROR_SUCCESS)
 915                 {
 916                         ereport(WARNING,
 917                                         (errmsg_internal("could not query value for 'std' to identify Windows timezone: %i", (int)r)));
 918                         RegCloseKey(key);
 919                         break;
 920                 }
 921                 if (strcmp(tzname, zonename) == 0)
 922                 {
 923                         /* Matched zone */
 924                         strcpy(localtzname, keyname);
 925                         RegCloseKey(key);
 926                         break;
 927                 }
 928                 memset(zonename, 0, sizeof(zonename));
 929                 namesize = sizeof(zonename);
 930                 if ((r=RegQueryValueEx(key, "Dlt", NULL, NULL, zonename, &namesize)) != ERROR_SUCCESS)
 931                 {
 932                         ereport(WARNING,
 933                                         (errmsg_internal("could not query value for 'dlt' to identify Windows timezone: %i", (int)r)));
 934                         RegCloseKey(key);
 935                         break;
 936                 }
 937                 if (strcmp(tzname, zonename) == 0)
 938                 {
 939                         /* Matched DST zone */
 940                         strcpy(localtzname, keyname);
 941                         RegCloseKey(key);
 942                         break;
 943                 }
 944
 945                 RegCloseKey(key);
 946         }
 947
 948         RegCloseKey(rootKey);
 949
 950         if (localtzname[0])
 951         {
 952                 /* Found a localized name, so scan for that one too */
 953                 for (i = 0; win32_tzmap[i].stdname != NULL; i++)
 954                 {
 955                         if (strcmp(localtzname, win32_tzmap[i].stdname) == 0 ||
 956                                 strcmp(localtzname, win32_tzmap[i].dstname) == 0)
 957                         {
 958                                 elog(DEBUG4, "TZ \"%s\" matches localized Windows timezone \"%s\" (\"%s\")",
 959                                          win32_tzmap[i].pgtzname, tzname, localtzname);
 960                                 return win32_tzmap[i].pgtzname;
 961                         }
 962                 }
 963         }
 964
 965         ereport(WARNING,
 966                         (errmsg("could not find a match for Windows timezone \"%s\"",
 967                                         tzname)));
 968         return NULL;
 969 }
 970 #endif   /* WIN32 */
 971
 972
 973
 974 /*
 975  * We keep loaded timezones in a hashtable so we don't have to
 976  * load and parse the TZ definition file every time it is selected.
 977  */
 978 static HTAB *timezone_cache = NULL;
 979
 980 static bool
 981 init_timezone_hashtable(void)
 982 {
 983         HASHCTL         hash_ctl;
 984
 985         MemSet(&hash_ctl, 0, sizeof(hash_ctl));
 986
 987         hash_ctl.keysize = TZ_STRLEN_MAX;
 988         hash_ctl.entrysize = sizeof(pg_tz);
 989
 990         timezone_cache = hash_create("Timezones",
 991                                                                  31,
 992                                                                  &hash_ctl,
 993                                                                  HASH_ELEM);
 994         if (!timezone_cache)
 995                 return false;
 996
 997         return true;
 998 }
 999
1000 /*
1001  * Load a timezone from file or from cache.
1002  * Does not verify that the timezone is acceptable!
1003  */
1004 struct pg_tz *
1005 pg_tzset(const char *name)
1006 {
1007         pg_tz *tzp;
1008         pg_tz tz;
1009
1010         if (strlen(name) >= TZ_STRLEN_MAX)
1011                 return NULL;                    /* not going to fit */
1012
1013         if (!timezone_cache)
1014                 if (!init_timezone_hashtable())
1015                         return NULL;
1016
1017         tzp = (pg_tz *)hash_search(timezone_cache,
1018                                                           name,
1019                                                           HASH_FIND,
1020                                                           NULL);
1021         if (tzp)
1022         {
1023                 /* Timezone found in cache, nothing more to do */
1024                 return tzp;
1025         }
1026
1027         if (tzload(name, &tz.state) != 0)
1028         {
1029                 if (name[0] == ':' || tzparse(name, &tz.state, FALSE) != 0)
1030                 {
1031                         /* Unknown timezone. Fail our call instead of loading GMT! */
1032                         return NULL;
1033                 }
1034         }
1035
1036         strcpy(tz.TZname, name);
1037
1038         /* Save timezone in the cache */
1039         tzp = hash_search(timezone_cache,
1040                                           name,
1041                                           HASH_ENTER,
1042                                           NULL);
1043
1044         strcpy(tzp->TZname, tz.TZname);
1045         memcpy(&tzp->state, &tz.state, sizeof(tz.state));
1046
1047         return tzp;
1048 }
1049
1050
1051 /*
1052  * Check whether timezone is acceptable.
1053  *
1054  * What we are doing here is checking for leap-second-aware timekeeping.
1055  * We need to reject such TZ settings because they'll wreak havoc with our
1056  * date/time arithmetic.
1057  *
1058  * NB: this must NOT ereport(ERROR).  The caller must get control back so that
1059  * it can restore the old value of TZ if we don't like the new one.
1060  */
1061 bool
1062 tz_acceptable(pg_tz *tz)
1063 {
1064         struct pg_tm *tt;
1065         pg_time_t       time2000;
1066
1067         /*
1068          * To detect leap-second timekeeping, run pg_localtime for what should
1069          * be GMT midnight, 2000-01-01.  Insist that the tm_sec value be zero;
1070          * any other result has to be due to leap seconds.
1071          */
1072         time2000 = (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY;
1073         tt = pg_localtime(&time2000, tz);
1074         if (!tt || tt->tm_sec != 0)
1075                 return false;
1076
1077         return true;
1078 }
1079
1080
1081 /*
1082  * Set the global timezone. Verify that it's acceptable first.
1083  */
1084 static bool
1085 set_global_timezone(const char *tzname)
1086 {
1087         pg_tz *tznew;
1088
1089         if (!tzname || !tzname[0])
1090                 return false;
1091
1092         tznew = pg_tzset(tzname);
1093         if (!tznew)
1094                 return false;
1095
1096         if (!tz_acceptable(tznew))
1097                 return false;
1098
1099         global_timezone = tznew;
1100         return true;
1101 }
1102
1103 /*
1104  * Identify a suitable default timezone setting based on the environment,
1105  * and make it active.
1106  *
1107  * We first look to the TZ environment variable.  If not found or not
1108  * recognized by our own code, we see if we can identify the timezone
1109  * from the behavior of the system timezone library.  When all else fails,
1110  * fall back to GMT.
1111  */
1112 static const char *
1113 select_default_timezone(void)
1114 {
1115         const char *def_tz;
1116
1117         def_tz = getenv("TZ");
1118         if (set_global_timezone(def_tz))
1119                 return def_tz;
1120
1121         def_tz = identify_system_timezone();
1122         if (set_global_timezone(def_tz))
1123                 return def_tz;
1124
1125         if (set_global_timezone("GMT"))
1126                 return "GMT";
1127
1128         ereport(FATAL,
1129                         (errmsg("could not select a suitable default timezone"),
1130                          errdetail("It appears that your GMT time zone uses leap seconds. PostgreSQL does not support leap seconds.")));
1131         return NULL;                            /* keep compiler quiet */
1132 }
1133
1134 /*
1135  * Initialize timezone library
1136  *
1137  * This is called after initial loading of postgresql.conf.  If no TimeZone
1138  * setting was found therein, we try to derive one from the environment.
1139  */
1140 void
1141 pg_timezone_initialize(void)
1142 {
1143         /* Do we need to try to figure the timezone? */
1144         if (pg_strcasecmp(GetConfigOption("timezone"), "UNKNOWN") == 0)
1145         {
1146                 const char *def_tz;
1147
1148                 /* Select setting */
1149                 def_tz = select_default_timezone();
1150                 /* Tell GUC about the value. Will redundantly call pg_tzset() */
1151                 SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ARGV);
1152         }
1153 }