1 /* Copyright (C) 1991,92,93,94,95,96,97,98 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 Boston, MA 02111-1307, USA. */
21 #include <bits/libc-lock.h>
28 /* Defined in mktime.c. */
29 extern const unsigned short int __mon_yday[2][13];
31 /* Defined in localtime.c. */
32 extern struct tm _tmbuf;
35 #include <timezone/tzfile.h>
37 extern int __use_tzfile;
38 extern void __tzfile_read __P ((const char *file));
39 extern int __tzfile_compute __P ((time_t timer, int use_localtime,
40 long int *leap_correct, int *leap_hit,
42 extern void __tzfile_default __P ((const char *std, const char *dst,
43 long int stdoff, long int dstoff));
44 extern char *__tzstring __P ((const char *string));
46 char *__tzname[2] = { (char *) "GMT", (char *) "GMT" };
48 long int __timezone = 0L;
50 weak_alias (__tzname, tzname)
51 weak_alias (__daylight, daylight)
52 weak_alias (__timezone, timezone)
54 /* This locks all the state variables in tzfile.c and this file. */
55 __libc_lock_define (static, tzset_lock)
58 #define min(a, b) ((a) < (b) ? (a) : (b))
59 #define max(a, b) ((a) > (b) ? (a) : (b))
60 #define sign(x) ((x) < 0 ? -1 : 1)
63 /* This structure contains all the information about a
64 timezone given in the POSIX standard TZ envariable. */
70 enum { J0, J1, M } type; /* Interpretation of: */
71 unsigned short int m, n, d; /* Month, week, day. */
72 unsigned int secs; /* Time of day. */
74 long int offset; /* Seconds east of GMT (west if < 0). */
76 /* We cache the computed time of change for a
77 given year so we don't have to recompute it. */
78 time_t change; /* When to change to this zone. */
79 int computed_for; /* Year above is computed for. */
82 /* tz_rules[0] is standard, tz_rules[1] is daylight. */
83 static tz_rule tz_rules[2];
86 static int compute_change __P ((tz_rule *rule, int year)) internal_function;
87 static int tz_compute __P ((time_t timer, const struct tm *tm))
89 static void tzset_internal __P ((int always)) internal_function;
91 /* Header for a list of buffers containing time zone strings. */
94 struct tzstring_head *next;
95 /* The buffer itself immediately follows the header.
96 The buffer contains zero or more (possibly overlapping) strings.
97 The last string is followed by 2 '\0's instead of the usual 1. */
100 /* First in a list of buffers containing time zone strings.
101 All the buffers but the last are read-only. */
104 struct tzstring_head head;
108 /* Size of the last buffer in the list, not counting its header. */
109 static size_t tzstring_last_buffer_size = sizeof tzstring_list.data;
111 /* Allocate a time zone string with given contents.
112 The string will never be moved or deallocated.
113 However, its contents may be shared with other such strings. */
118 struct tzstring_head *h = &tzstring_list.head;
122 /* Look through time zone string list for a duplicate of this one. */
123 for (h = &tzstring_list.head; ; h = h->next)
125 for (p = (char *) (h + 1); p[0] | p[1]; ++p)
126 if (strcmp (p, string) == 0)
132 /* No duplicate was found. Copy to the end of this buffer if there's room;
133 otherwise, append a large-enough new buffer to the list and use it. */
135 needed = strlen (string) + 2; /* Need 2 trailing '\0's after last string. */
137 if ((size_t) ((char *) (h + 1) + tzstring_last_buffer_size - p) < needed)
139 size_t buffer_size = tzstring_last_buffer_size;
140 while ((buffer_size *= 2) < needed)
142 if (! (h = h->next = malloc (sizeof *h + buffer_size)))
145 tzstring_last_buffer_size = buffer_size;
146 p = (char *) (h + 1);
149 return strncpy (p, string, needed);
152 static char *old_tz = NULL;
154 /* Interpret the TZ envariable. */
157 tzset_internal (always)
160 static int is_initialized = 0;
161 register const char *tz;
164 unsigned short int hh, mm, ss;
165 unsigned short int whichrule;
167 if (is_initialized && !always)
171 /* Examine the TZ environment variable. */
174 /* No user specification; use the site-wide default. */
176 else if (*tz == '\0')
177 /* User specified the empty string; use UTC explicitly. */
180 /* A leading colon means "implementation defined syntax".
181 We ignore the colon and always use the same algorithm:
182 try a data file, and if none exists parse the 1003.1 syntax. */
183 if (tz && *tz == ':')
186 /* Check whether the value changes since the last run. */
187 if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0)
188 /* No change, simply return. */
191 tz_rules[0].name = NULL;
192 tz_rules[1].name = NULL;
194 /* Save the value of `tz'. */
197 old_tz = tz ? __strdup (tz) : NULL;
199 /* Try to read a data file. */
204 /* No data file found. Default to UTC if nothing specified. */
206 if (tz == NULL || *tz == '\0')
208 tz_rules[0].name = tz_rules[1].name = "UTC";
209 tz_rules[0].type = tz_rules[1].type = J0;
210 tz_rules[0].m = tz_rules[0].n = tz_rules[0].d = 0;
211 tz_rules[1].m = tz_rules[1].n = tz_rules[1].d = 0;
212 tz_rules[0].secs = tz_rules[1].secs = 0;
213 tz_rules[0].offset = tz_rules[1].offset = 0L;
214 tz_rules[0].change = tz_rules[1].change = (time_t) -1;
215 tz_rules[0].computed_for = tz_rules[1].computed_for = 0;
219 /* Clear out old state and reset to unnamed UTC. */
220 memset (tz_rules, 0, sizeof tz_rules);
221 tz_rules[0].name = tz_rules[1].name = "";
223 /* Get the standard timezone name. */
224 tzbuf = malloc (strlen (tz) + 1);
227 /* Clear the old tz name so we will try again. */
233 if (sscanf (tz, "%[^0-9,+-]", tzbuf) != 1 ||
234 (l = strlen (tzbuf)) < 3)
240 tz_rules[0].name = __tzstring (tzbuf);
244 /* Figure out the standard offset from UTC. */
245 if (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit (*tz)))
251 if (*tz == '-' || *tz == '+')
252 tz_rules[0].offset = *tz++ == '-' ? 1L : -1L;
254 tz_rules[0].offset = -1L;
255 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
267 tz_rules[0].offset *= (min (ss, 59) + (min (mm, 59) * 60) +
268 (min (hh, 23) * 60 * 60));
270 for (l = 0; l < 3; ++l)
274 if (l < 2 && *tz == ':')
278 /* Get the DST timezone name (if any). */
281 char *n = tzbuf + strlen (tzbuf) + 1;
282 if (sscanf (tz, "%[^0-9,+-]", n) != 1 ||
283 (l = strlen (n)) < 3)
284 goto done_names; /* Punt on name, set up the offsets. */
286 tz_rules[1].name = __tzstring (n);
290 /* Figure out the DST offset from GMT. */
291 if (*tz == '-' || *tz == '+')
292 tz_rules[1].offset = *tz++ == '-' ? 1L : -1L;
294 tz_rules[1].offset = -1L;
296 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
299 /* Default to one hour later than standard time. */
300 tz_rules[1].offset = tz_rules[0].offset + (60 * 60);
308 tz_rules[1].offset *= (min (ss, 59) + (min (mm, 59) * 60) +
309 (min (hh, 23) * (60 * 60)));
312 for (l = 0; l < 3; ++l)
314 while (isdigit (*tz))
316 if (l < 2 && *tz == ':')
319 if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0'))
321 /* There is no rule. See if there is a default rule file. */
322 __tzfile_default (tz_rules[0].name, tz_rules[1].name,
323 tz_rules[0].offset, tz_rules[1].offset);
335 /* There is no DST. */
336 tz_rules[1].name = tz_rules[0].name;
337 tz_rules[1].offset = tz_rules[0].offset;
345 /* Figure out the standard <-> DST rules. */
346 for (whichrule = 0; whichrule < 2; ++whichrule)
348 register tz_rule *tzr = &tz_rules[whichrule];
350 /* Ignore comma to support string following the incorrect
351 specification in early POSIX.1 printings. */
354 /* Get the date of the change. */
355 if (*tz == 'J' || isdigit (*tz))
358 tzr->type = *tz == 'J' ? J1 : J0;
359 if (tzr->type == J1 && !isdigit (*++tz))
361 tzr->d = (unsigned short int) strtoul (tz, &end, 10);
362 if (end == tz || tzr->d > 365)
364 else if (tzr->type == J1 && tzr->d == 0)
372 if (sscanf (tz, "M%hu.%hu.%hu%n",
373 &tzr->m, &tzr->n, &tzr->d, &n) != 3 ||
374 tzr->m < 1 || tzr->m > 12 ||
375 tzr->n < 1 || tzr->n > 5 || tzr->d > 6)
379 else if (*tz == '\0')
381 /* United States Federal Law, the equivalent of "M4.1.0,M10.5.0". */
383 if (tzr == &tz_rules[0])
399 if (*tz != '\0' && *tz != '/' && *tz != ',')
403 /* Get the time of day of the change. */
407 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
410 hh = 2; /* Default to 2:00 AM. */
418 for (l = 0; l < 3; ++l)
420 while (isdigit (*tz))
422 if (l < 2 && *tz == ':')
425 tzr->secs = (hh * 60 * 60) + (mm * 60) + ss;
428 /* Default to 2:00 AM. */
429 tzr->secs = 2 * 60 * 60;
431 tzr->computed_for = -1;
435 /* Maximum length of a timezone name. __tz_compute keeps this up to date
436 (never decreasing it) when ! __use_tzfile.
437 tzfile.c keeps it up to date when __use_tzfile. */
438 size_t __tzname_cur_max;
443 __libc_lock_lock (tzset_lock);
447 __libc_lock_unlock (tzset_lock);
449 return __tzname_cur_max;
452 /* Figure out the exact time (as a time_t) in YEAR
453 when the change described by RULE will occur and
454 put it in RULE->change, saving YEAR in RULE->computed_for.
455 Return nonzero if successful, zero on failure. */
458 compute_change (rule, year)
465 if (year != -1 && rule->computed_for == year)
466 /* Operations on times in 1969 will be slower. Oh well. */
469 /* First set T to January 1st, 0:00:00 GMT in YEAR. */
471 for (y = 1970; y < year; ++y)
472 t += SECSPERDAY * (__isleap (y) ? 366 : 365);
477 /* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years.
478 In non-leap years, or if the day number is 59 or less, just
479 add SECSPERDAY times the day number-1 to the time of
480 January 1, midnight, to get the day. */
481 t += (rule->d - 1) * SECSPERDAY;
482 if (rule->d >= 60 && __isleap (year))
488 Just add SECSPERDAY times the day number to the time of Jan 1st. */
489 t += rule->d * SECSPERDAY;
493 /* Mm.n.d - Nth "Dth day" of month M. */
496 int d, m1, yy0, yy1, yy2, dow;
497 const unsigned short int *myday =
498 &__mon_yday[__isleap (year)][rule->m];
500 /* First add SECSPERDAY for each day in months before M. */
501 t += myday[-1] * SECSPERDAY;
503 /* Use Zeller's Congruence to get day-of-week of first day of month. */
504 m1 = (rule->m + 9) % 12 + 1;
505 yy0 = (rule->m <= 2) ? (year - 1) : year;
508 dow = ((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
512 /* DOW is the day-of-week of the first day of the month. Get the
513 day-of-month (zero-origin) of the first DOW day of the month. */
517 for (i = 1; i < rule->n; ++i)
519 if (d + 7 >= (int) myday[0] - myday[-1])
524 /* D is the day-of-month (zero-origin) of the day we want. */
530 /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want.
531 Just add the time of day and local offset from GMT, and we're done. */
533 rule->change = t - rule->offset + rule->secs;
534 rule->computed_for = year;
539 /* Figure out the correct timezone for *TIMER and TM (which must be the same)
540 and set `__tzname', `__timezone', and `__daylight' accordingly.
541 Return nonzero on success, zero on failure. */
544 tz_compute (timer, tm)
548 if (! compute_change (&tz_rules[0], 1900 + tm->tm_year) ||
549 ! compute_change (&tz_rules[1], 1900 + tm->tm_year))
552 __daylight = tz_rules[0].offset != tz_rules[1].offset;
553 __timezone = -tz_rules[0].offset;
554 __tzname[0] = (char *) tz_rules[0].name;
555 __tzname[1] = (char *) tz_rules[1].name;
558 /* Keep __tzname_cur_max up to date. */
559 size_t len0 = strlen (__tzname[0]);
560 size_t len1 = strlen (__tzname[1]);
561 if (len0 > __tzname_cur_max)
562 __tzname_cur_max = len0;
563 if (len1 > __tzname_cur_max)
564 __tzname_cur_max = len1;
570 /* Reinterpret the TZ environment variable and set `tzname'. */
576 __libc_lock_lock (tzset_lock);
583 __tzname[0] = (char *) tz_rules[0].name;
584 __tzname[1] = (char *) tz_rules[1].name;
587 __libc_lock_unlock (tzset_lock);
589 weak_alias (__tzset, tzset)
591 /* Return the `struct tm' representation of *TIMER in the local timezone.
592 Use local time if USE_LOCALTIME is nonzero, UTC otherwise. */
594 __tz_convert (const time_t *timer, int use_localtime, struct tm *tp)
596 long int leap_correction;
601 __set_errno (EINVAL);
605 __libc_lock_lock (tzset_lock);
607 /* Update internal database according to current TZ setting.
608 POSIX.1 8.3.7.2 says that localtime_r is not required to set tzname.
609 This is a good idea since this allows at least a bit more parallelism.
610 By analogy we apply the same rule to gmtime_r. */
611 tzset_internal (tp == &_tmbuf);
615 if (! __tzfile_compute (*timer, use_localtime,
616 &leap_correction, &leap_extra_secs, tp))
621 if (! (__offtime (timer, 0, tp) && tz_compute (*timer, tp)))
623 leap_correction = 0L;
633 int isdst = (*timer >= tz_rules[0].change
634 && *timer < tz_rules[1].change);
635 tp->tm_isdst = isdst;
636 tp->tm_zone = __tzname[isdst];
637 tp->tm_gmtoff = tz_rules[isdst].offset;
647 if (__offtime (timer, tp->tm_gmtoff - leap_correction, tp))
648 tp->tm_sec += leap_extra_secs;
653 __libc_lock_unlock (tzset_lock);