1 | /* Copyright (C) 1991-2018 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
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 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <ctype.h> |
19 | #include <errno.h> |
20 | #include <libc-lock.h> |
21 | #include <stdbool.h> |
22 | #include <stddef.h> |
23 | #include <stdio.h> |
24 | #include <stdlib.h> |
25 | #include <string.h> |
26 | #include <time.h> |
27 | |
28 | #include <timezone/tzfile.h> |
29 | |
30 | #define SECSPERDAY 86400 |
31 | |
32 | char *__tzname[2] = { (char *) "GMT" , (char *) "GMT" }; |
33 | int __daylight = 0; |
34 | long int __timezone = 0L; |
35 | |
36 | weak_alias (__tzname, tzname) |
37 | weak_alias (__daylight, daylight) |
38 | weak_alias (__timezone, timezone) |
39 | |
40 | /* This locks all the state variables in tzfile.c and this file. */ |
41 | __libc_lock_define_initialized (static, tzset_lock) |
42 | |
43 | /* This structure contains all the information about a |
44 | timezone given in the POSIX standard TZ envariable. */ |
45 | typedef struct |
46 | { |
47 | const char *name; |
48 | |
49 | /* When to change. */ |
50 | enum { J0, J1, M } type; /* Interpretation of: */ |
51 | unsigned short int m, n, d; /* Month, week, day. */ |
52 | int secs; /* Time of day. */ |
53 | |
54 | long int offset; /* Seconds east of GMT (west if < 0). */ |
55 | |
56 | /* We cache the computed time of change for a |
57 | given year so we don't have to recompute it. */ |
58 | time_t change; /* When to change to this zone. */ |
59 | int computed_for; /* Year above is computed for. */ |
60 | } tz_rule; |
61 | |
62 | /* tz_rules[0] is standard, tz_rules[1] is daylight. */ |
63 | static tz_rule tz_rules[2]; |
64 | |
65 | |
66 | static void compute_change (tz_rule *rule, int year) __THROW; |
67 | static void tzset_internal (int always); |
68 | |
69 | /* List of buffers containing time zone strings. */ |
70 | struct tzstring_l |
71 | { |
72 | struct tzstring_l *next; |
73 | size_t len; /* strlen(data) - doesn't count terminating NUL! */ |
74 | char data[0]; |
75 | }; |
76 | |
77 | static struct tzstring_l *tzstring_list; |
78 | |
79 | /* Allocate a permanent home for the first LEN characters of S. It |
80 | will never be moved or deallocated, but may share space with other |
81 | strings. Don't modify the returned string. */ |
82 | static char * |
83 | __tzstring_len (const char *s, size_t len) |
84 | { |
85 | char *p; |
86 | struct tzstring_l *t, *u, *new; |
87 | |
88 | /* Walk the list and look for a match. If this string is the same |
89 | as the end of an already-allocated string, it can share space. */ |
90 | for (u = t = tzstring_list; t; u = t, t = t->next) |
91 | if (len <= t->len) |
92 | { |
93 | p = &t->data[t->len - len]; |
94 | if (memcmp (s, p, len) == 0) |
95 | return p; |
96 | } |
97 | |
98 | /* Not found; allocate a new buffer. */ |
99 | new = malloc (sizeof (struct tzstring_l) + len + 1); |
100 | if (!new) |
101 | return NULL; |
102 | |
103 | new->next = NULL; |
104 | new->len = len; |
105 | memcpy (new->data, s, len); |
106 | new->data[len] = '\0'; |
107 | |
108 | if (u) |
109 | u->next = new; |
110 | else |
111 | tzstring_list = new; |
112 | |
113 | return new->data; |
114 | } |
115 | |
116 | /* Allocate a permanent home for S. It will never be moved or |
117 | deallocated, but may share space with other strings. Don't modify |
118 | the returned string. */ |
119 | char * |
120 | __tzstring (const char *s) |
121 | { |
122 | return __tzstring_len (s, strlen (s)); |
123 | } |
124 | |
125 | static char *old_tz; |
126 | |
127 | static void |
128 | update_vars (void) |
129 | { |
130 | __daylight = tz_rules[0].offset != tz_rules[1].offset; |
131 | __timezone = -tz_rules[0].offset; |
132 | __tzname[0] = (char *) tz_rules[0].name; |
133 | __tzname[1] = (char *) tz_rules[1].name; |
134 | } |
135 | |
136 | |
137 | static unsigned int |
138 | compute_offset (unsigned int ss, unsigned int mm, unsigned int hh) |
139 | { |
140 | if (ss > 59) |
141 | ss = 59; |
142 | if (mm > 59) |
143 | mm = 59; |
144 | if (hh > 24) |
145 | hh = 24; |
146 | return ss + mm * 60 + hh * 60 * 60; |
147 | } |
148 | |
149 | /* Parses the time zone name at *TZP, and writes a pointer to an |
150 | interned string to tz_rules[WHICHRULE].name. On success, advances |
151 | *TZP, and returns true. Returns false otherwise. */ |
152 | static bool |
153 | parse_tzname (const char **tzp, int whichrule) |
154 | { |
155 | const char *start = *tzp; |
156 | const char *p = start; |
157 | while (('a' <= *p && *p <= 'z') |
158 | || ('A' <= *p && *p <= 'Z')) |
159 | ++p; |
160 | size_t len = p - start; |
161 | if (len < 3) |
162 | { |
163 | p = *tzp; |
164 | if (__glibc_unlikely (*p++ != '<')) |
165 | return false; |
166 | start = p; |
167 | while (('a' <= *p && *p <= 'z') |
168 | || ('A' <= *p && *p <= 'Z') |
169 | || ('0' <= *p && *p <= '9') |
170 | || *p == '+' || *p == '-') |
171 | ++p; |
172 | len = p - start; |
173 | if (*p++ != '>' || len < 3) |
174 | return false; |
175 | } |
176 | |
177 | const char *name = __tzstring_len (start, len); |
178 | if (name == NULL) |
179 | return false; |
180 | tz_rules[whichrule].name = name; |
181 | |
182 | *tzp = p; |
183 | return true; |
184 | } |
185 | |
186 | /* Parses the time zone offset at *TZP, and writes it to |
187 | tz_rules[WHICHRULE].offset. Returns true if the parse was |
188 | successful. */ |
189 | static bool |
190 | parse_offset (const char **tzp, int whichrule) |
191 | { |
192 | const char *tz = *tzp; |
193 | if (whichrule == 0 |
194 | && (*tz == '\0' || (*tz != '+' && *tz != '-' && !isdigit (*tz)))) |
195 | return false; |
196 | |
197 | long sign; |
198 | if (*tz == '-' || *tz == '+') |
199 | sign = *tz++ == '-' ? 1L : -1L; |
200 | else |
201 | sign = -1L; |
202 | *tzp = tz; |
203 | |
204 | unsigned short int hh; |
205 | unsigned short mm = 0; |
206 | unsigned short ss = 0; |
207 | int consumed = 0; |
208 | if (sscanf (tz, "%hu%n:%hu%n:%hu%n" , |
209 | &hh, &consumed, &mm, &consumed, &ss, &consumed) > 0) |
210 | tz_rules[whichrule].offset = sign * compute_offset (ss, mm, hh); |
211 | else |
212 | /* Nothing could be parsed. */ |
213 | if (whichrule == 0) |
214 | { |
215 | /* Standard time defaults to offset zero. */ |
216 | tz_rules[0].offset = 0; |
217 | return false; |
218 | } |
219 | else |
220 | /* DST defaults to one hour later than standard time. */ |
221 | tz_rules[1].offset = tz_rules[0].offset + (60 * 60); |
222 | *tzp = tz + consumed; |
223 | return true; |
224 | } |
225 | |
226 | /* Parses the standard <-> DST rules at *TZP. Updates |
227 | tz_rule[WHICHRULE]. On success, advances *TZP and returns true. |
228 | Otherwise, returns false. */ |
229 | static bool |
230 | parse_rule (const char **tzp, int whichrule) |
231 | { |
232 | const char *tz = *tzp; |
233 | tz_rule *tzr = &tz_rules[whichrule]; |
234 | |
235 | /* Ignore comma to support string following the incorrect |
236 | specification in early POSIX.1 printings. */ |
237 | tz += *tz == ','; |
238 | |
239 | /* Get the date of the change. */ |
240 | if (*tz == 'J' || isdigit (*tz)) |
241 | { |
242 | char *end; |
243 | tzr->type = *tz == 'J' ? J1 : J0; |
244 | if (tzr->type == J1 && !isdigit (*++tz)) |
245 | return false; |
246 | unsigned long int d = strtoul (tz, &end, 10); |
247 | if (end == tz || d > 365) |
248 | return false; |
249 | if (tzr->type == J1 && d == 0) |
250 | return false; |
251 | tzr->d = d; |
252 | tz = end; |
253 | } |
254 | else if (*tz == 'M') |
255 | { |
256 | tzr->type = M; |
257 | int consumed; |
258 | if (sscanf (tz, "M%hu.%hu.%hu%n" , |
259 | &tzr->m, &tzr->n, &tzr->d, &consumed) != 3 |
260 | || tzr->m < 1 || tzr->m > 12 |
261 | || tzr->n < 1 || tzr->n > 5 || tzr->d > 6) |
262 | return false; |
263 | tz += consumed; |
264 | } |
265 | else if (*tz == '\0') |
266 | { |
267 | /* Daylight time rules in the U.S. are defined in the U.S. Code, |
268 | Title 15, Chapter 6, Subchapter IX - Standard Time. These |
269 | dates were established by Congress in the Energy Policy Act |
270 | of 2005 [Pub. L. no. 109-58, 119 Stat 594 (2005)]. |
271 | Below is the equivalent of "M3.2.0,M11.1.0" [/2 not needed |
272 | since 2:00AM is the default]. */ |
273 | tzr->type = M; |
274 | if (tzr == &tz_rules[0]) |
275 | { |
276 | tzr->m = 3; |
277 | tzr->n = 2; |
278 | tzr->d = 0; |
279 | } |
280 | else |
281 | { |
282 | tzr->m = 11; |
283 | tzr->n = 1; |
284 | tzr->d = 0; |
285 | } |
286 | } |
287 | else |
288 | return false; |
289 | |
290 | if (*tz != '\0' && *tz != '/' && *tz != ',') |
291 | return false; |
292 | else if (*tz == '/') |
293 | { |
294 | /* Get the time of day of the change. */ |
295 | int negative; |
296 | ++tz; |
297 | if (*tz == '\0') |
298 | return false; |
299 | negative = *tz == '-'; |
300 | tz += negative; |
301 | /* Default to 2:00 AM. */ |
302 | unsigned short hh = 2; |
303 | unsigned short mm = 0; |
304 | unsigned short ss = 0; |
305 | int consumed = 0; |
306 | sscanf (tz, "%hu%n:%hu%n:%hu%n" , |
307 | &hh, &consumed, &mm, &consumed, &ss, &consumed);; |
308 | tz += consumed; |
309 | tzr->secs = (negative ? -1 : 1) * ((hh * 60 * 60) + (mm * 60) + ss); |
310 | } |
311 | else |
312 | /* Default to 2:00 AM. */ |
313 | tzr->secs = 2 * 60 * 60; |
314 | |
315 | tzr->computed_for = -1; |
316 | *tzp = tz; |
317 | return true; |
318 | } |
319 | |
320 | /* Parse the POSIX TZ-style string. */ |
321 | void |
322 | __tzset_parse_tz (const char *tz) |
323 | { |
324 | /* Clear out old state and reset to unnamed UTC. */ |
325 | memset (tz_rules, '\0', sizeof tz_rules); |
326 | tz_rules[0].name = tz_rules[1].name = "" ; |
327 | |
328 | /* Get the standard timezone name. */ |
329 | if (parse_tzname (&tz, 0) && parse_offset (&tz, 0)) |
330 | { |
331 | /* Get the DST timezone name (if any). */ |
332 | if (*tz != '\0') |
333 | { |
334 | if (parse_tzname (&tz, 1)) |
335 | { |
336 | parse_offset (&tz, 1); |
337 | if (*tz == '\0' || (tz[0] == ',' && tz[1] == '\0')) |
338 | { |
339 | /* There is no rule. See if there is a default rule |
340 | file. */ |
341 | __tzfile_default (tz_rules[0].name, tz_rules[1].name, |
342 | tz_rules[0].offset, tz_rules[1].offset); |
343 | if (__use_tzfile) |
344 | { |
345 | free (old_tz); |
346 | old_tz = NULL; |
347 | return; |
348 | } |
349 | } |
350 | } |
351 | /* Figure out the standard <-> DST rules. */ |
352 | if (parse_rule (&tz, 0)) |
353 | parse_rule (&tz, 1); |
354 | } |
355 | else |
356 | { |
357 | /* There is no DST. */ |
358 | tz_rules[1].name = tz_rules[0].name; |
359 | tz_rules[1].offset = tz_rules[0].offset; |
360 | } |
361 | } |
362 | |
363 | update_vars (); |
364 | } |
365 | |
366 | /* Interpret the TZ envariable. */ |
367 | static void |
368 | tzset_internal (int always) |
369 | { |
370 | static int is_initialized; |
371 | const char *tz; |
372 | |
373 | if (is_initialized && !always) |
374 | return; |
375 | is_initialized = 1; |
376 | |
377 | /* Examine the TZ environment variable. */ |
378 | tz = getenv ("TZ" ); |
379 | if (tz && *tz == '\0') |
380 | /* User specified the empty string; use UTC explicitly. */ |
381 | tz = "Universal" ; |
382 | |
383 | /* A leading colon means "implementation defined syntax". |
384 | We ignore the colon and always use the same algorithm: |
385 | try a data file, and if none exists parse the 1003.1 syntax. */ |
386 | if (tz && *tz == ':') |
387 | ++tz; |
388 | |
389 | /* Check whether the value changed since the last run. */ |
390 | if (old_tz != NULL && tz != NULL && strcmp (tz, old_tz) == 0) |
391 | /* No change, simply return. */ |
392 | return; |
393 | |
394 | if (tz == NULL) |
395 | /* No user specification; use the site-wide default. */ |
396 | tz = TZDEFAULT; |
397 | |
398 | tz_rules[0].name = NULL; |
399 | tz_rules[1].name = NULL; |
400 | |
401 | /* Save the value of `tz'. */ |
402 | free (old_tz); |
403 | old_tz = tz ? __strdup (tz) : NULL; |
404 | |
405 | /* Try to read a data file. */ |
406 | __tzfile_read (tz, 0, NULL); |
407 | if (__use_tzfile) |
408 | return; |
409 | |
410 | /* No data file found. Default to UTC if nothing specified. */ |
411 | |
412 | if (tz == NULL || *tz == '\0' |
413 | || (TZDEFAULT != NULL && strcmp (tz, TZDEFAULT) == 0)) |
414 | { |
415 | memset (tz_rules, '\0', sizeof tz_rules); |
416 | tz_rules[0].name = tz_rules[1].name = "UTC" ; |
417 | if (J0 != 0) |
418 | tz_rules[0].type = tz_rules[1].type = J0; |
419 | tz_rules[0].change = tz_rules[1].change = (time_t) -1; |
420 | update_vars (); |
421 | return; |
422 | } |
423 | |
424 | __tzset_parse_tz (tz); |
425 | } |
426 | |
427 | /* Figure out the exact time (as a time_t) in YEAR |
428 | when the change described by RULE will occur and |
429 | put it in RULE->change, saving YEAR in RULE->computed_for. */ |
430 | static void |
431 | compute_change (tz_rule *rule, int year) |
432 | { |
433 | time_t t; |
434 | |
435 | if (year != -1 && rule->computed_for == year) |
436 | /* Operations on times in 2 BC will be slower. Oh well. */ |
437 | return; |
438 | |
439 | /* First set T to January 1st, 0:00:00 GMT in YEAR. */ |
440 | if (year > 1970) |
441 | t = ((year - 1970) * 365 |
442 | + /* Compute the number of leapdays between 1970 and YEAR |
443 | (exclusive). There is a leapday every 4th year ... */ |
444 | + ((year - 1) / 4 - 1970 / 4) |
445 | /* ... except every 100th year ... */ |
446 | - ((year - 1) / 100 - 1970 / 100) |
447 | /* ... but still every 400th year. */ |
448 | + ((year - 1) / 400 - 1970 / 400)) * SECSPERDAY; |
449 | else |
450 | t = 0; |
451 | |
452 | switch (rule->type) |
453 | { |
454 | case J1: |
455 | /* Jn - Julian day, 1 == January 1, 60 == March 1 even in leap years. |
456 | In non-leap years, or if the day number is 59 or less, just |
457 | add SECSPERDAY times the day number-1 to the time of |
458 | January 1, midnight, to get the day. */ |
459 | t += (rule->d - 1) * SECSPERDAY; |
460 | if (rule->d >= 60 && __isleap (year)) |
461 | t += SECSPERDAY; |
462 | break; |
463 | |
464 | case J0: |
465 | /* n - Day of year. |
466 | Just add SECSPERDAY times the day number to the time of Jan 1st. */ |
467 | t += rule->d * SECSPERDAY; |
468 | break; |
469 | |
470 | case M: |
471 | /* Mm.n.d - Nth "Dth day" of month M. */ |
472 | { |
473 | unsigned int i; |
474 | int d, m1, yy0, yy1, yy2, dow; |
475 | const unsigned short int *myday = |
476 | &__mon_yday[__isleap (year)][rule->m]; |
477 | |
478 | /* First add SECSPERDAY for each day in months before M. */ |
479 | t += myday[-1] * SECSPERDAY; |
480 | |
481 | /* Use Zeller's Congruence to get day-of-week of first day of month. */ |
482 | m1 = (rule->m + 9) % 12 + 1; |
483 | yy0 = (rule->m <= 2) ? (year - 1) : year; |
484 | yy1 = yy0 / 100; |
485 | yy2 = yy0 % 100; |
486 | dow = ((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7; |
487 | if (dow < 0) |
488 | dow += 7; |
489 | |
490 | /* DOW is the day-of-week of the first day of the month. Get the |
491 | day-of-month (zero-origin) of the first DOW day of the month. */ |
492 | d = rule->d - dow; |
493 | if (d < 0) |
494 | d += 7; |
495 | for (i = 1; i < rule->n; ++i) |
496 | { |
497 | if (d + 7 >= (int) myday[0] - myday[-1]) |
498 | break; |
499 | d += 7; |
500 | } |
501 | |
502 | /* D is the day-of-month (zero-origin) of the day we want. */ |
503 | t += d * SECSPERDAY; |
504 | } |
505 | break; |
506 | } |
507 | |
508 | /* T is now the Epoch-relative time of 0:00:00 GMT on the day we want. |
509 | Just add the time of day and local offset from GMT, and we're done. */ |
510 | |
511 | rule->change = t - rule->offset + rule->secs; |
512 | rule->computed_for = year; |
513 | } |
514 | |
515 | |
516 | /* Figure out the correct timezone for TM and set `__tzname', |
517 | `__timezone', and `__daylight' accordingly. */ |
518 | void |
519 | __tz_compute (time_t timer, struct tm *tm, int use_localtime) |
520 | { |
521 | compute_change (&tz_rules[0], 1900 + tm->tm_year); |
522 | compute_change (&tz_rules[1], 1900 + tm->tm_year); |
523 | |
524 | if (use_localtime) |
525 | { |
526 | int isdst; |
527 | |
528 | /* We have to distinguish between northern and southern |
529 | hemisphere. For the latter the daylight saving time |
530 | ends in the next year. */ |
531 | if (__builtin_expect (tz_rules[0].change |
532 | > tz_rules[1].change, 0)) |
533 | isdst = (timer < tz_rules[1].change |
534 | || timer >= tz_rules[0].change); |
535 | else |
536 | isdst = (timer >= tz_rules[0].change |
537 | && timer < tz_rules[1].change); |
538 | tm->tm_isdst = isdst; |
539 | tm->tm_zone = __tzname[isdst]; |
540 | tm->tm_gmtoff = tz_rules[isdst].offset; |
541 | } |
542 | } |
543 | |
544 | /* Reinterpret the TZ environment variable and set `tzname'. */ |
545 | #undef tzset |
546 | |
547 | void |
548 | __tzset (void) |
549 | { |
550 | __libc_lock_lock (tzset_lock); |
551 | |
552 | tzset_internal (1); |
553 | |
554 | if (!__use_tzfile) |
555 | { |
556 | /* Set `tzname'. */ |
557 | __tzname[0] = (char *) tz_rules[0].name; |
558 | __tzname[1] = (char *) tz_rules[1].name; |
559 | } |
560 | |
561 | __libc_lock_unlock (tzset_lock); |
562 | } |
563 | weak_alias (__tzset, tzset) |
564 | |
565 | /* Return the `struct tm' representation of *TIMER in the local timezone. |
566 | Use local time if USE_LOCALTIME is nonzero, UTC otherwise. */ |
567 | struct tm * |
568 | __tz_convert (const time_t *timer, int use_localtime, struct tm *tp) |
569 | { |
570 | long int leap_correction; |
571 | int ; |
572 | |
573 | if (timer == NULL) |
574 | { |
575 | __set_errno (EINVAL); |
576 | return NULL; |
577 | } |
578 | |
579 | __libc_lock_lock (tzset_lock); |
580 | |
581 | /* Update internal database according to current TZ setting. |
582 | POSIX.1 8.3.7.2 says that localtime_r is not required to set tzname. |
583 | This is a good idea since this allows at least a bit more parallelism. */ |
584 | tzset_internal (tp == &_tmbuf && use_localtime); |
585 | |
586 | if (__use_tzfile) |
587 | __tzfile_compute (*timer, use_localtime, &leap_correction, |
588 | &leap_extra_secs, tp); |
589 | else |
590 | { |
591 | if (! __offtime (timer, 0, tp)) |
592 | tp = NULL; |
593 | else |
594 | __tz_compute (*timer, tp, use_localtime); |
595 | leap_correction = 0L; |
596 | leap_extra_secs = 0; |
597 | } |
598 | |
599 | __libc_lock_unlock (tzset_lock); |
600 | |
601 | if (tp) |
602 | { |
603 | if (! use_localtime) |
604 | { |
605 | tp->tm_isdst = 0; |
606 | tp->tm_zone = "GMT" ; |
607 | tp->tm_gmtoff = 0L; |
608 | } |
609 | |
610 | if (__offtime (timer, tp->tm_gmtoff - leap_correction, tp)) |
611 | tp->tm_sec += leap_extra_secs; |
612 | else |
613 | tp = NULL; |
614 | } |
615 | |
616 | return tp; |
617 | } |
618 | |
619 | |
620 | libc_freeres_fn (free_mem) |
621 | { |
622 | while (tzstring_list != NULL) |
623 | { |
624 | struct tzstring_l *old = tzstring_list; |
625 | |
626 | tzstring_list = tzstring_list->next; |
627 | free (old); |
628 | } |
629 | free (old_tz); |
630 | old_tz = NULL; |
631 | } |
632 | |