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
16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
17 Cambridge, MA 02139, USA. */
27 /* Defined in mktime.c. */
28 extern CONST unsigned short int __mon_yday[2][13];
33 extern int __use_tzfile;
34 extern void EXFUN(__tzfile_read, (CONST char *file));
35 extern void EXFUN(__tzfile_default, (char *std AND char *dst AND
36 long int stdoff AND long int dstoff));
37 extern int EXFUN(__tzfile_compute, (time_t, struct tm));
39 char *__tzname[2] = { (char *) "GMT", (char *) "GMT" };
41 long int __timezone = 0L;
43 weak_alias (__tzname, tzname)
44 weak_alias (__daylight, daylight)
45 weak_alias (__timezone, timezone)
48 #define min(a, b) ((a) < (b) ? (a) : (b))
49 #define max(a, b) ((a) > (b) ? (a) : (b))
50 #define sign(x) ((x) < 0 ? -1 : 1)
53 /* This structure contains all the information about a
54 timezone given in the POSIX standard TZ envariable. */
60 enum { J0, J1, M } type; /* Interpretation of: */
61 unsigned short int m, n, d; /* Month, week, day. */
62 unsigned int secs; /* Time of day. */
64 long int offset; /* Seconds east of GMT (west if < 0). */
66 /* We cache the computed time of change for a
67 given year so we don't have to recompute it. */
68 time_t change; /* When to change to this zone. */
69 int computed_for; /* Year above is computed for. */
72 /* tz_rules[0] is standard, tz_rules[1] is daylight. */
73 static tz_rule tz_rules[2];
77 /* Interpret the TZ envariable. */
81 register CONST char *tz;
83 unsigned short int hh, mm, ss;
84 unsigned short int whichrule;
86 /* Free old storage. */
87 if (tz_rules[0].name != NULL && *tz_rules[0].name != '\0')
88 free((PTR) tz_rules[0].name);
89 if (tz_rules[1].name != NULL && *tz_rules[1].name != '\0' &&
90 tz_rules[1].name != tz_rules[0].name)
91 free((PTR) tz_rules[1].name);
93 /* Examine the TZ environment variable. */
98 /* A leading colon means "implementation defined syntax".
99 We ignore the colon and always use the same algorithm:
100 try a data file, and if none exists parse the 1003.1 syntax. */
112 if (tz == NULL || *tz == '\0')
114 __tzfile_read((char *) NULL);
117 const char UTC[] = "UTC";
118 size_t len = sizeof UTC;
119 tz_rules[0].name = (char *) malloc(len);
120 if (tz_rules[0].name == NULL)
122 tz_rules[1].name = (char *) malloc(len);
123 if (tz_rules[1].name == NULL)
125 memcpy ((PTR) tz_rules[0].name, UTC, len);
126 memcpy ((PTR) tz_rules[1].name, UTC, len);
127 tz_rules[0].type = tz_rules[1].type = J0;
128 tz_rules[0].m = tz_rules[0].n = tz_rules[0].d = 0;
129 tz_rules[1].m = tz_rules[1].n = tz_rules[1].d = 0;
130 tz_rules[0].secs = tz_rules[1].secs = 0;
131 tz_rules[0].offset = tz_rules[1].offset = 0L;
132 tz_rules[0].change = tz_rules[1].change = (time_t) -1;
133 tz_rules[0].computed_for = tz_rules[1].computed_for = 0;
139 /* Clear out old state and reset to unnamed UTC. */
140 memset (tz_rules, 0, sizeof tz_rules);
141 tz_rules[0].name = tz_rules[1].name = (char *) "";
143 /* Get the standard timezone name. */
144 tz_rules[0].name = (char *) malloc (strlen (tz) + 1);
145 if (tz_rules[0].name == NULL)
146 /* Don't set __tzset_run so we will try again. */
149 if (sscanf(tz, "%[^0-9,+-]", tz_rules[0].name) != 1 ||
150 (l = strlen(tz_rules[0].name)) < 3)
152 free (tz_rules[0].name);
153 tz_rules[0].name = (char *) "";
158 char *n = realloc ((PTR) tz_rules[0].name, l + 1);
160 tz_rules[0].name = n;
165 /* Figure out the standard offset from UTC. */
166 if (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit(*tz)))
169 if (*tz == '-' || *tz == '+')
170 tz_rules[0].offset = *tz++ == '-' ? 1L : -1L;
172 tz_rules[0].offset = -1L;
173 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
184 tz_rules[0].offset *= (min(ss, 59) + (min(mm, 59) * 60) +
185 (min(hh, 23) * 60 * 60));
187 for (l = 0; l < 3; ++l)
191 if (l < 2 && *tz == ':')
195 /* Get the DST timezone name (if any). */
198 char *n = malloc (strlen(tz) + 1);
201 tz_rules[1].name = n;
202 if (sscanf(tz, "%[^0-9,+-]", tz_rules[1].name) != 1 ||
203 (l = strlen(tz_rules[1].name)) < 3)
206 tz_rules[1].name = (char *) "";
207 goto done_names; /* Punt on name, set up the offsets. */
209 n = realloc ((PTR) tz_rules[1].name, l + 1);
211 tz_rules[1].name = n;
217 /* Figure out the DST offset from GMT. */
218 if (*tz == '-' || *tz == '+')
219 tz_rules[1].offset = *tz++ == '-' ? 1L : -1L;
221 tz_rules[1].offset = -1L;
223 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
226 /* Default to one hour later than standard time. */
227 tz_rules[1].offset = tz_rules[0].offset + (60 * 60);
235 tz_rules[1].offset *= (min(ss, 59) + (min(mm, 59) * 60) +
236 (min(hh, 23) * (60 * 60)));
239 for (l = 0; l < 3; ++l)
241 while (isdigit (*tz))
243 if (l < 2 && *tz == ':')
249 if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0'))
251 /* There is no rule. See if there is a default rule file. */
252 __tzfile_default (tz_rules[0].name, tz_rules[1].name,
253 tz_rules[0].offset, tz_rules[1].offset);
261 /* Figure out the standard <-> DST rules. */
262 for (whichrule = 0; whichrule < 2; ++whichrule)
264 register tz_rule *tzr = &tz_rules[whichrule];
273 /* Get the date of the change. */
274 if (*tz == 'J' || isdigit (*tz))
277 tzr->type = *tz == 'J' ? J1 : J0;
278 if (tzr->type == J1 && !isdigit (*++tz))
280 tzr->d = (unsigned short int) strtoul (tz, &end, 10);
281 if (end == tz || tzr->d > 365)
283 else if (tzr->type == J1 && tzr->d == 0)
291 if (sscanf (tz, "M%hu.%hu.%hu%n",
292 &tzr->m, &tzr->n, &tzr->d, &n) != 3 ||
293 tzr->m < 1 || tzr->m > 12 ||
294 tzr->n < 1 || tzr->n > 5 || tzr->d > 6)
298 else if (*tz == '\0')
300 /* United States Federal Law, the equivalent of "M4.1.0,M10.5.0". */
302 if (tzr == &tz_rules[0])
318 if (*tz != '\0' && *tz != '/' && *tz != ',')
322 /* Get the time of day of the change. */
326 switch (sscanf (tz, "%hu:%hu:%hu", &hh, &mm, &ss))
329 hh = 2; /* Default to 2:00 AM. */
337 for (l = 0; l < 3; ++l)
341 if (l < 2 && *tz == ':')
344 tzr->secs = (hh * 60 * 60) + (mm * 60) + ss;
347 /* Default to 2:00 AM. */
348 tzr->secs = 2 * 60 * 60;
350 tzr->computed_for = -1;
356 /* Maximum length of a timezone name. __tz_compute keeps this up to date
357 (never decreasing it) when ! __use_tzfile.
358 tzfile.c keeps it up to date when __use_tzfile. */
359 long int __tzname_cur_max;
362 DEFUN_VOID(__tzname_max)
367 return __tzname_cur_max;
370 /* Figure out the exact time (as a time_t) in YEAR
371 when the change described by RULE will occur and
372 put it in RULE->change, saving YEAR in RULE->computed_for.
373 Return nonzero if successful, zero on failure. */
375 DEFUN(compute_change, (rule, year), tz_rule *rule AND int year)
380 if (year != -1 && rule->computed_for == year)
381 /* Operations on times in 1969 will be slower. Oh well. */
384 /* First set T to January 1st, 0:00:00 GMT in YEAR. */
386 for (y = 1970; y < year; ++y)
387 t += SECSPERDAY * (__isleap (y) ? 366 : 365);
392 /* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years.
393 In non-leap years, or if the day number is 59 or less, just
394 add SECSPERDAY times the day number-1 to the time of
395 January 1, midnight, to get the day. */
396 t += (rule->d - 1) * SECSPERDAY;
397 if (rule->d >= 60 && __isleap (year))
403 Just add SECSPERDAY times the day number to the time of Jan 1st. */
404 t += rule->d * SECSPERDAY;
408 /* Mm.n.d - Nth "Dth day" of month M. */
410 register int i, d, m1, yy0, yy1, yy2, dow;
411 register CONST unsigned short int *myday =
412 &__mon_yday[__isleap (year)][rule->m];
414 /* First add SECSPERDAY for each day in months before M. */
415 t += myday[-1] * SECSPERDAY;
417 /* Use Zeller's Congruence to get day-of-week of first day of month. */
418 m1 = (rule->m + 9) % 12 + 1;
419 yy0 = (rule->m <= 2) ? (year - 1) : year;
422 dow = ((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
426 /* DOW is the day-of-week of the first day of the month. Get the
427 day-of-month (zero-origin) of the first DOW day of the month. */
431 for (i = 1; i < rule->n; ++i)
433 if (d + 7 >= myday[0] - myday[-1])
438 /* D is the day-of-month (zero-origin) of the day we want. */
444 /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want.
445 Just add the time of day and local offset from GMT, and we're done. */
447 rule->change = t + rule->offset + rule->secs;
448 rule->computed_for = year;
453 /* Figure out the correct timezone for *TIMER and TM (which must be the same)
454 and set `__tzname', `__timezone', and `__daylight' accordingly.
455 Return nonzero on success, zero on failure. */
457 DEFUN(__tz_compute, (timer, tm),
458 time_t timer AND const struct tm *tm)
463 if (! compute_change (&tz_rules[0], 1900 + tm->tm_year) ||
464 ! compute_change (&tz_rules[1], 1900 + tm->tm_year))
467 __daylight = timer >= tz_rules[0].change && timer < tz_rules[1].change;
468 __timezone = tz_rules[__daylight ? 1 : 0].offset;
469 __tzname[0] = (char *) tz_rules[0].name;
470 __tzname[1] = (char *) tz_rules[1].name;
473 /* Keep __tzname_cur_max up to date. */
474 size_t len0 = strlen (__tzname[0]);
475 size_t len1 = strlen (__tzname[1]);
476 if (len0 > __tzname_cur_max)
477 __tzname_cur_max = len0;
478 if (len1 > __tzname_cur_max)
479 __tzname_cur_max = len1;
485 weak_alias (__tzset, tzset)