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));
77 static char *old_tz = NULL;
79 /* Interpret the TZ envariable. */
83 register const char *tz;
85 unsigned short int hh, mm, ss;
86 unsigned short int whichrule;
88 /* Examine the TZ environment variable. */
91 /* A leading colon means "implementation defined syntax".
92 We ignore the colon and always use the same algorithm:
93 try a data file, and if none exists parse the 1003.1 syntax. */
97 /* Check whether the value changes since the last run. */
98 if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0)
99 /* No change, simply return. */
102 /* Free old storage. */
103 if (tz_rules[0].name != NULL && *tz_rules[0].name != '\0')
105 free((void *) tz_rules[0].name);
106 tz_rules[0].name = NULL;
108 if (tz_rules[1].name != NULL && *tz_rules[1].name != '\0' &&
109 tz_rules[1].name != tz_rules[0].name)
111 free((void *) tz_rules[1].name);
112 tz_rules[1].name = NULL;
115 /* Save the value of `tz'. */
118 old_tz = tz ? __strdup (tz) : NULL;
120 /* Try to read a data file. */
125 /* No data file found. Default to UTC if nothing specified. */
127 if (tz == NULL || *tz == '\0')
129 static const char UTC[] = "UTC";
130 size_t len = sizeof UTC;
131 tz_rules[0].name = (char *) malloc (len);
132 if (tz_rules[0].name == NULL)
134 tz_rules[1].name = (char *) malloc (len);
135 if (tz_rules[1].name == NULL)
137 memcpy ((void *) tz_rules[0].name, UTC, len);
138 memcpy ((void *) tz_rules[1].name, UTC, len);
139 tz_rules[0].type = tz_rules[1].type = J0;
140 tz_rules[0].m = tz_rules[0].n = tz_rules[0].d = 0;
141 tz_rules[1].m = tz_rules[1].n = tz_rules[1].d = 0;
142 tz_rules[0].secs = tz_rules[1].secs = 0;
143 tz_rules[0].offset = tz_rules[1].offset = 0L;
144 tz_rules[0].change = tz_rules[1].change = (time_t) -1;
145 tz_rules[0].computed_for = tz_rules[1].computed_for = 0;
149 /* Clear out old state and reset to unnamed UTC. */
150 memset (tz_rules, 0, sizeof tz_rules);
151 tz_rules[0].name = tz_rules[1].name = (char *) "";
153 /* Get the standard timezone name. */
154 tz_rules[0].name = (char *) malloc (strlen (tz) + 1);
155 if (tz_rules[0].name == NULL)
157 /* Clear the old tz name so we will try again. */
163 if (sscanf(tz, "%[^0-9,+-]", tz_rules[0].name) != 1 ||
164 (l = strlen(tz_rules[0].name)) < 3)
166 free (tz_rules[0].name);
167 tz_rules[0].name = (char *) "";
172 char *n = realloc ((void *) tz_rules[0].name, l + 1);
174 tz_rules[0].name = n;
179 /* Figure out the standard offset from UTC. */
180 if (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit(*tz)))
183 if (*tz == '-' || *tz == '+')
184 tz_rules[0].offset = *tz++ == '-' ? 1L : -1L;
186 tz_rules[0].offset = -1L;
187 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
198 tz_rules[0].offset *= (min (ss, 59) + (min (mm, 59) * 60) +
199 (min (hh, 23) * 60 * 60));
201 for (l = 0; l < 3; ++l)
205 if (l < 2 && *tz == ':')
209 /* Get the DST timezone name (if any). */
212 char *n = malloc (strlen (tz) + 1);
215 tz_rules[1].name = n;
216 if (sscanf (tz, "%[^0-9,+-]", tz_rules[1].name) != 1 ||
217 (l = strlen (tz_rules[1].name)) < 3)
220 tz_rules[1].name = (char *) "";
221 goto done_names; /* Punt on name, set up the offsets. */
223 n = realloc ((void *) tz_rules[1].name, l + 1);
225 tz_rules[1].name = n;
231 /* Figure out the DST offset from GMT. */
232 if (*tz == '-' || *tz == '+')
233 tz_rules[1].offset = *tz++ == '-' ? 1L : -1L;
235 tz_rules[1].offset = -1L;
237 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
240 /* Default to one hour later than standard time. */
241 tz_rules[1].offset = tz_rules[0].offset + (60 * 60);
249 tz_rules[1].offset *= (min (ss, 59) + (min (mm, 59) * 60) +
250 (min (hh, 23) * (60 * 60)));
253 for (l = 0; l < 3; ++l)
255 while (isdigit (*tz))
257 if (l < 2 && *tz == ':')
263 if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0'))
265 /* There is no rule. See if there is a default rule file. */
266 __tzfile_default (tz_rules[0].name, tz_rules[1].name,
267 tz_rules[0].offset, tz_rules[1].offset);
276 /* Figure out the standard <-> DST rules. */
277 for (whichrule = 0; whichrule < 2; ++whichrule)
279 register tz_rule *tzr = &tz_rules[whichrule];
288 /* Get the date of the change. */
289 if (*tz == 'J' || isdigit (*tz))
292 tzr->type = *tz == 'J' ? J1 : J0;
293 if (tzr->type == J1 && !isdigit (*++tz))
295 tzr->d = (unsigned short int) strtoul (tz, &end, 10);
296 if (end == tz || tzr->d > 365)
298 else if (tzr->type == J1 && tzr->d == 0)
306 if (sscanf (tz, "M%hu.%hu.%hu%n",
307 &tzr->m, &tzr->n, &tzr->d, &n) != 3 ||
308 tzr->m < 1 || tzr->m > 12 ||
309 tzr->n < 1 || tzr->n > 5 || tzr->d > 6)
313 else if (*tz == '\0')
315 /* United States Federal Law, the equivalent of "M4.1.0,M10.5.0". */
317 if (tzr == &tz_rules[0])
333 if (*tz != '\0' && *tz != '/' && *tz != ',')
337 /* Get the time of day of the change. */
341 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
344 hh = 2; /* Default to 2:00 AM. */
352 for (l = 0; l < 3; ++l)
354 while (isdigit (*tz))
356 if (l < 2 && *tz == ':')
359 tzr->secs = (hh * 60 * 60) + (mm * 60) + ss;
362 /* Default to 2:00 AM. */
363 tzr->secs = 2 * 60 * 60;
365 tzr->computed_for = -1;
369 /* Maximum length of a timezone name. __tz_compute keeps this up to date
370 (never decreasing it) when ! __use_tzfile.
371 tzfile.c keeps it up to date when __use_tzfile. */
372 size_t __tzname_cur_max;
379 return __tzname_cur_max;
382 /* Figure out the exact time (as a time_t) in YEAR
383 when the change described by RULE will occur and
384 put it in RULE->change, saving YEAR in RULE->computed_for.
385 Return nonzero if successful, zero on failure. */
387 compute_change (rule, year)
394 if (year != -1 && rule->computed_for == year)
395 /* Operations on times in 1969 will be slower. Oh well. */
398 /* First set T to January 1st, 0:00:00 GMT in YEAR. */
400 for (y = 1970; y < year; ++y)
401 t += SECSPERDAY * (__isleap (y) ? 366 : 365);
406 /* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years.
407 In non-leap years, or if the day number is 59 or less, just
408 add SECSPERDAY times the day number-1 to the time of
409 January 1, midnight, to get the day. */
410 t += (rule->d - 1) * SECSPERDAY;
411 if (rule->d >= 60 && __isleap (year))
417 Just add SECSPERDAY times the day number to the time of Jan 1st. */
418 t += rule->d * SECSPERDAY;
422 /* Mm.n.d - Nth "Dth day" of month M. */
424 register int i, d, m1, yy0, yy1, yy2, dow;
425 register const unsigned short int *myday =
426 &__mon_yday[__isleap (year)][rule->m];
428 /* First add SECSPERDAY for each day in months before M. */
429 t += myday[-1] * SECSPERDAY;
431 /* Use Zeller's Congruence to get day-of-week of first day of month. */
432 m1 = (rule->m + 9) % 12 + 1;
433 yy0 = (rule->m <= 2) ? (year - 1) : year;
436 dow = ((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
440 /* DOW is the day-of-week of the first day of the month. Get the
441 day-of-month (zero-origin) of the first DOW day of the month. */
445 for (i = 1; i < rule->n; ++i)
447 if (d + 7 >= myday[0] - myday[-1])
452 /* D is the day-of-month (zero-origin) of the day we want. */
458 /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want.
459 Just add the time of day and local offset from GMT, and we're done. */
461 rule->change = t - rule->offset + rule->secs;
462 rule->computed_for = year;
467 /* Figure out the correct timezone for *TIMER and TM (which must be the same)
468 and set `__tzname', `__timezone', and `__daylight' accordingly.
469 Return nonzero on success, zero on failure. */
471 __tz_compute (timer, tm)
477 if (! compute_change (&tz_rules[0], 1900 + tm->tm_year) ||
478 ! compute_change (&tz_rules[1], 1900 + tm->tm_year))
481 __daylight = timer >= tz_rules[0].change && timer < tz_rules[1].change;
482 __timezone = tz_rules[__daylight ? 1 : 0].offset;
483 __tzname[0] = (char *) tz_rules[0].name;
484 __tzname[1] = (char *) tz_rules[1].name;
487 /* Keep __tzname_cur_max up to date. */
488 size_t len0 = strlen (__tzname[0]);
489 size_t len1 = strlen (__tzname[1]);
490 if (len0 > __tzname_cur_max)
491 __tzname_cur_max = len0;
492 if (len1 > __tzname_cur_max)
493 __tzname_cur_max = len1;
499 #include <libc-lock.h>
501 /* This locks all the state variables in tzfile.c and this file. */
502 __libc_lock_define (, __tzset_lock)
504 /* Reinterpret the TZ environment variable and set `tzname'. */
510 __libc_lock_lock (__tzset_lock);
517 __tzname[0] = (char *) tz_rules[0].name;
518 __tzname[1] = (char *) tz_rules[1].name;
521 __libc_lock_unlock (__tzset_lock);
523 weak_alias (__tzset, tzset)