1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 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. */
26 /* Defined in mktime.c. */
27 extern const unsigned short int __mon_yday[2][13];
32 extern int __use_tzfile;
33 extern void __tzfile_read __P ((const char *file));
34 extern void __tzfile_default __P ((char *std, char *dst,
35 long int stdoff, long int dstoff));
36 extern int __tz_compute __P ((time_t timer, const struct tm *tm));
38 char *__tzname[2] = { (char *) "GMT", (char *) "GMT" };
40 long int __timezone = 0L;
42 weak_alias (__tzname, tzname)
43 weak_alias (__daylight, daylight)
44 weak_alias (__timezone, timezone)
47 #define min(a, b) ((a) < (b) ? (a) : (b))
48 #define max(a, b) ((a) > (b) ? (a) : (b))
49 #define sign(x) ((x) < 0 ? -1 : 1)
52 /* This structure contains all the information about a
53 timezone given in the POSIX standard TZ envariable. */
59 enum { J0, J1, M } type; /* Interpretation of: */
60 unsigned short int m, n, d; /* Month, week, day. */
61 unsigned int secs; /* Time of day. */
63 long int offset; /* Seconds east of GMT (west if < 0). */
65 /* We cache the computed time of change for a
66 given year so we don't have to recompute it. */
67 time_t change; /* When to change to this zone. */
68 int computed_for; /* Year above is computed for. */
71 /* tz_rules[0] is standard, tz_rules[1] is daylight. */
72 static tz_rule tz_rules[2];
75 static int compute_change __P ((tz_rule *rule, int year));
79 /* Interpret the TZ envariable. */
83 register const char *tz;
85 unsigned short int hh, mm, ss;
86 unsigned short int whichrule;
88 /* Free old storage. */
89 if (tz_rules[0].name != NULL && *tz_rules[0].name != '\0')
91 free((void *) tz_rules[0].name);
92 tz_rules[0].name = NULL;
94 if (tz_rules[1].name != NULL && *tz_rules[1].name != '\0' &&
95 tz_rules[1].name != tz_rules[0].name)
97 free((void *) tz_rules[1].name);
98 tz_rules[1].name = NULL;
101 /* Examine the TZ environment variable. */
104 /* A leading colon means "implementation defined syntax".
105 We ignore the colon and always use the same algorithm:
106 try a data file, and if none exists parse the 1003.1 syntax. */
107 if (tz && *tz == ':')
110 /* Try to read a data file. */
118 /* No data file found. Default to UTC if nothing specified. */
120 if (tz == NULL || *tz == '\0')
122 static const char UTC[] = "UTC";
123 size_t len = sizeof UTC;
124 tz_rules[0].name = (char *) malloc(len);
125 if (tz_rules[0].name == NULL)
127 tz_rules[1].name = (char *) malloc(len);
128 if (tz_rules[1].name == NULL)
130 memcpy ((void *) tz_rules[0].name, UTC, len);
131 memcpy ((void *) tz_rules[1].name, UTC, len);
132 tz_rules[0].type = tz_rules[1].type = J0;
133 tz_rules[0].m = tz_rules[0].n = tz_rules[0].d = 0;
134 tz_rules[1].m = tz_rules[1].n = tz_rules[1].d = 0;
135 tz_rules[0].secs = tz_rules[1].secs = 0;
136 tz_rules[0].offset = tz_rules[1].offset = 0L;
137 tz_rules[0].change = tz_rules[1].change = (time_t) -1;
138 tz_rules[0].computed_for = tz_rules[1].computed_for = 0;
143 /* Clear out old state and reset to unnamed UTC. */
144 memset (tz_rules, 0, sizeof tz_rules);
145 tz_rules[0].name = tz_rules[1].name = (char *) "";
147 /* Get the standard timezone name. */
148 tz_rules[0].name = (char *) malloc (strlen (tz) + 1);
149 if (tz_rules[0].name == NULL)
150 /* Don't set __tzset_run so we will try again. */
153 if (sscanf(tz, "%[^0-9,+-]", tz_rules[0].name) != 1 ||
154 (l = strlen(tz_rules[0].name)) < 3)
156 free (tz_rules[0].name);
157 tz_rules[0].name = (char *) "";
162 char *n = realloc ((void *) tz_rules[0].name, l + 1);
164 tz_rules[0].name = n;
169 /* Figure out the standard offset from UTC. */
170 if (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit(*tz)))
173 if (*tz == '-' || *tz == '+')
174 tz_rules[0].offset = *tz++ == '-' ? 1L : -1L;
176 tz_rules[0].offset = -1L;
177 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
188 tz_rules[0].offset *= (min (ss, 59) + (min (mm, 59) * 60) +
189 (min (hh, 23) * 60 * 60));
191 for (l = 0; l < 3; ++l)
195 if (l < 2 && *tz == ':')
199 /* Get the DST timezone name (if any). */
202 char *n = malloc (strlen (tz) + 1);
205 tz_rules[1].name = n;
206 if (sscanf (tz, "%[^0-9,+-]", tz_rules[1].name) != 1 ||
207 (l = strlen (tz_rules[1].name)) < 3)
210 tz_rules[1].name = (char *) "";
211 goto done_names; /* Punt on name, set up the offsets. */
213 n = realloc ((void *) tz_rules[1].name, l + 1);
215 tz_rules[1].name = n;
221 /* Figure out the DST offset from GMT. */
222 if (*tz == '-' || *tz == '+')
223 tz_rules[1].offset = *tz++ == '-' ? 1L : -1L;
225 tz_rules[1].offset = -1L;
227 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
230 /* Default to one hour later than standard time. */
231 tz_rules[1].offset = tz_rules[0].offset + (60 * 60);
239 tz_rules[1].offset *= (min (ss, 59) + (min (mm, 59) * 60) +
240 (min (hh, 23) * (60 * 60)));
243 for (l = 0; l < 3; ++l)
245 while (isdigit (*tz))
247 if (l < 2 && *tz == ':')
253 if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0'))
255 /* There is no rule. See if there is a default rule file. */
256 __tzfile_default (tz_rules[0].name, tz_rules[1].name,
257 tz_rules[0].offset, tz_rules[1].offset);
265 /* Figure out the standard <-> DST rules. */
266 for (whichrule = 0; whichrule < 2; ++whichrule)
268 register tz_rule *tzr = &tz_rules[whichrule];
277 /* Get the date of the change. */
278 if (*tz == 'J' || isdigit (*tz))
281 tzr->type = *tz == 'J' ? J1 : J0;
282 if (tzr->type == J1 && !isdigit (*++tz))
284 tzr->d = (unsigned short int) strtoul (tz, &end, 10);
285 if (end == tz || tzr->d > 365)
287 else if (tzr->type == J1 && tzr->d == 0)
295 if (sscanf (tz, "M%hu.%hu.%hu%n",
296 &tzr->m, &tzr->n, &tzr->d, &n) != 3 ||
297 tzr->m < 1 || tzr->m > 12 ||
298 tzr->n < 1 || tzr->n > 5 || tzr->d > 6)
302 else if (*tz == '\0')
304 /* United States Federal Law, the equivalent of "M4.1.0,M10.5.0". */
306 if (tzr == &tz_rules[0])
322 if (*tz != '\0' && *tz != '/' && *tz != ',')
326 /* Get the time of day of the change. */
330 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
333 hh = 2; /* Default to 2:00 AM. */
341 for (l = 0; l < 3; ++l)
343 while (isdigit (*tz))
345 if (l < 2 && *tz == ':')
348 tzr->secs = (hh * 60 * 60) + (mm * 60) + ss;
351 /* Default to 2:00 AM. */
352 tzr->secs = 2 * 60 * 60;
354 tzr->computed_for = -1;
360 /* Maximum length of a timezone name. __tz_compute keeps this up to date
361 (never decreasing it) when ! __use_tzfile.
362 tzfile.c keeps it up to date when __use_tzfile. */
363 size_t __tzname_cur_max;
371 return __tzname_cur_max;
374 /* Figure out the exact time (as a time_t) in YEAR
375 when the change described by RULE will occur and
376 put it in RULE->change, saving YEAR in RULE->computed_for.
377 Return nonzero if successful, zero on failure. */
379 compute_change (rule, year)
386 if (year != -1 && rule->computed_for == year)
387 /* Operations on times in 1969 will be slower. Oh well. */
390 /* First set T to January 1st, 0:00:00 GMT in YEAR. */
392 for (y = 1970; y < year; ++y)
393 t += SECSPERDAY * (__isleap (y) ? 366 : 365);
398 /* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years.
399 In non-leap years, or if the day number is 59 or less, just
400 add SECSPERDAY times the day number-1 to the time of
401 January 1, midnight, to get the day. */
402 t += (rule->d - 1) * SECSPERDAY;
403 if (rule->d >= 60 && __isleap (year))
409 Just add SECSPERDAY times the day number to the time of Jan 1st. */
410 t += rule->d * SECSPERDAY;
414 /* Mm.n.d - Nth "Dth day" of month M. */
416 register int i, d, m1, yy0, yy1, yy2, dow;
417 register const unsigned short int *myday =
418 &__mon_yday[__isleap (year)][rule->m];
420 /* First add SECSPERDAY for each day in months before M. */
421 t += myday[-1] * SECSPERDAY;
423 /* Use Zeller's Congruence to get day-of-week of first day of month. */
424 m1 = (rule->m + 9) % 12 + 1;
425 yy0 = (rule->m <= 2) ? (year - 1) : year;
428 dow = ((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
432 /* DOW is the day-of-week of the first day of the month. Get the
433 day-of-month (zero-origin) of the first DOW day of the month. */
437 for (i = 1; i < rule->n; ++i)
439 if (d + 7 >= myday[0] - myday[-1])
444 /* D is the day-of-month (zero-origin) of the day we want. */
450 /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want.
451 Just add the time of day and local offset from GMT, and we're done. */
453 rule->change = t + rule->offset + rule->secs;
454 rule->computed_for = year;
459 /* Figure out the correct timezone for *TIMER and TM (which must be the same)
460 and set `__tzname', `__timezone', and `__daylight' accordingly.
461 Return nonzero on success, zero on failure. */
463 __tz_compute (timer, tm)
470 if (! compute_change (&tz_rules[0], 1900 + tm->tm_year) ||
471 ! compute_change (&tz_rules[1], 1900 + tm->tm_year))
474 __daylight = timer >= tz_rules[0].change && timer < tz_rules[1].change;
475 __timezone = tz_rules[__daylight ? 1 : 0].offset;
476 __tzname[0] = (char *) tz_rules[0].name;
477 __tzname[1] = (char *) tz_rules[1].name;
480 /* Keep __tzname_cur_max up to date. */
481 size_t len0 = strlen (__tzname[0]);
482 size_t len1 = strlen (__tzname[1]);
483 if (len0 > __tzname_cur_max)
484 __tzname_cur_max = len0;
485 if (len1 > __tzname_cur_max)
486 __tzname_cur_max = len1;
492 #include <libc-lock.h>
494 /* This locks all the state variables in tzfile.c and this file. */
495 __libc_lock_define (, __tzset_lock)
497 /* Reinterpret the TZ environment variable and set `tzname'. */
506 __libc_lock_lock (__tzset_lock);
508 __libc_lock_unlock (__tzset_lock);