1 /* Copyright (C) 1991-2017 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 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.
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.
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/>. */
20 #include <libc-lock.h>
28 #include <timezone/tzfile.h>
30 char *__tzname
[2] = { (char *) "GMT", (char *) "GMT" };
32 long int __timezone
= 0L;
34 weak_alias (__tzname
, tzname
)
35 weak_alias (__daylight
, daylight
)
36 weak_alias (__timezone
, timezone
)
38 /* This locks all the state variables in tzfile.c and this file. */
39 __libc_lock_define_initialized (static, tzset_lock
)
41 /* This structure contains all the information about a
42 timezone given in the POSIX standard TZ envariable. */
48 enum { J0
, J1
, M
} type
; /* Interpretation of: */
49 unsigned short int m
, n
, d
; /* Month, week, day. */
50 int secs
; /* Time of day. */
52 long int offset
; /* Seconds east of GMT (west if < 0). */
54 /* We cache the computed time of change for a
55 given year so we don't have to recompute it. */
56 time_t change
; /* When to change to this zone. */
57 int computed_for
; /* Year above is computed for. */
60 /* tz_rules[0] is standard, tz_rules[1] is daylight. */
61 static tz_rule tz_rules
[2];
64 static void compute_change (tz_rule
*rule
, int year
) __THROW internal_function
;
65 static void tzset_internal (int always
);
67 /* List of buffers containing time zone strings. */
70 struct tzstring_l
*next
;
71 size_t len
; /* strlen(data) - doesn't count terminating NUL! */
75 static struct tzstring_l
*tzstring_list
;
77 /* Allocate a permanent home for the first LEN characters of S. It
78 will never be moved or deallocated, but may share space with other
79 strings. Don't modify the returned string. */
81 __tzstring_len (const char *s
, size_t len
)
84 struct tzstring_l
*t
, *u
, *new;
86 /* Walk the list and look for a match. If this string is the same
87 as the end of an already-allocated string, it can share space. */
88 for (u
= t
= tzstring_list
; t
; u
= t
, t
= t
->next
)
91 p
= &t
->data
[t
->len
- len
];
92 if (memcmp (s
, p
, len
) == 0)
96 /* Not found; allocate a new buffer. */
97 new = malloc (sizeof (struct tzstring_l
) + len
+ 1);
103 memcpy (new->data
, s
, len
);
104 new->data
[len
] = '\0';
114 /* Allocate a permanent home for S. It will never be moved or
115 deallocated, but may share space with other strings. Don't modify
116 the returned string. */
118 __tzstring (const char *s
)
120 return __tzstring_len (s
, strlen (s
));
129 __daylight
= tz_rules
[0].offset
!= tz_rules
[1].offset
;
130 __timezone
= -tz_rules
[0].offset
;
131 __tzname
[0] = (char *) tz_rules
[0].name
;
132 __tzname
[1] = (char *) tz_rules
[1].name
;
137 compute_offset (unsigned int ss
, unsigned int mm
, unsigned int hh
)
145 return ss
+ mm
* 60 + hh
* 60 * 60;
148 /* Parses the time zone name at *TZP, and writes a pointer to an
149 interned string to tz_rules[WHICHRULE].name. On success, advances
150 *TZP, and returns true. Returns false otherwise. */
152 parse_tzname (const char **tzp
, int whichrule
)
154 const char *start
= *tzp
;
155 const char *p
= start
;
156 while (('a' <= *p
&& *p
<= 'z')
157 || ('A' <= *p
&& *p
<= 'Z'))
159 size_t len
= p
- start
;
163 if (__glibc_unlikely (*p
++ != '<'))
166 while (('a' <= *p
&& *p
<= 'z')
167 || ('A' <= *p
&& *p
<= 'Z')
168 || ('0' <= *p
&& *p
<= '9')
169 || *p
== '+' || *p
== '-')
172 if (*p
++ != '>' || len
< 3)
176 const char *name
= __tzstring_len (start
, len
);
179 tz_rules
[whichrule
].name
= name
;
185 /* Parses the time zone offset at *TZP, and writes it to
186 tz_rules[WHICHRULE].offset. Returns true if the parse was
189 parse_offset (const char **tzp
, int whichrule
)
191 const char *tz
= *tzp
;
193 && (*tz
== '\0' || (*tz
!= '+' && *tz
!= '-' && !isdigit (*tz
))))
197 if (*tz
== '-' || *tz
== '+')
198 sign
= *tz
++ == '-' ? 1L : -1L;
203 unsigned short int hh
;
204 unsigned short mm
= 0;
205 unsigned short ss
= 0;
207 if (sscanf (tz
, "%hu%n:%hu%n:%hu%n",
208 &hh
, &consumed
, &mm
, &consumed
, &ss
, &consumed
) > 0)
209 tz_rules
[whichrule
].offset
= sign
* compute_offset (ss
, mm
, hh
);
211 /* Nothing could be parsed. */
214 /* Standard time defaults to offset zero. */
215 tz_rules
[0].offset
= 0;
219 /* DST defaults to one hour later than standard time. */
220 tz_rules
[1].offset
= tz_rules
[0].offset
+ (60 * 60);
221 *tzp
= tz
+ consumed
;
225 /* Parses the standard <-> DST rules at *TZP. Updates
226 tz_rule[WHICHRULE]. On success, advances *TZP and returns true.
227 Otherwise, returns false. */
229 parse_rule (const char **tzp
, int whichrule
)
231 const char *tz
= *tzp
;
232 tz_rule
*tzr
= &tz_rules
[whichrule
];
234 /* Ignore comma to support string following the incorrect
235 specification in early POSIX.1 printings. */
238 /* Get the date of the change. */
239 if (*tz
== 'J' || isdigit (*tz
))
242 tzr
->type
= *tz
== 'J' ? J1
: J0
;
243 if (tzr
->type
== J1
&& !isdigit (*++tz
))
245 unsigned long int d
= strtoul (tz
, &end
, 10);
246 if (end
== tz
|| d
> 365)
248 if (tzr
->type
== J1
&& d
== 0)
257 if (sscanf (tz
, "M%hu.%hu.%hu%n",
258 &tzr
->m
, &tzr
->n
, &tzr
->d
, &consumed
) != 3
259 || tzr
->m
< 1 || tzr
->m
> 12
260 || tzr
->n
< 1 || tzr
->n
> 5 || tzr
->d
> 6)
264 else if (*tz
== '\0')
266 /* Daylight time rules in the U.S. are defined in the U.S. Code,
267 Title 15, Chapter 6, Subchapter IX - Standard Time. These
268 dates were established by Congress in the Energy Policy Act
269 of 2005 [Pub. L. no. 109-58, 119 Stat 594 (2005)].
270 Below is the equivalent of "M3.2.0,M11.1.0" [/2 not needed
271 since 2:00AM is the default]. */
273 if (tzr
== &tz_rules
[0])
289 if (*tz
!= '\0' && *tz
!= '/' && *tz
!= ',')
293 /* Get the time of day of the change. */
298 negative
= *tz
== '-';
300 /* Default to 2:00 AM. */
301 unsigned short hh
= 2;
302 unsigned short mm
= 0;
303 unsigned short ss
= 0;
305 sscanf (tz
, "%hu%n:%hu%n:%hu%n",
306 &hh
, &consumed
, &mm
, &consumed
, &ss
, &consumed
);;
308 tzr
->secs
= (negative
? -1 : 1) * ((hh
* 60 * 60) + (mm
* 60) + ss
);
311 /* Default to 2:00 AM. */
312 tzr
->secs
= 2 * 60 * 60;
314 tzr
->computed_for
= -1;
319 /* Parse the POSIX TZ-style string. */
321 __tzset_parse_tz (const char *tz
)
323 /* Clear out old state and reset to unnamed UTC. */
324 memset (tz_rules
, '\0', sizeof tz_rules
);
325 tz_rules
[0].name
= tz_rules
[1].name
= "";
327 /* Get the standard timezone name. */
328 if (parse_tzname (&tz
, 0) && parse_offset (&tz
, 0))
330 /* Get the DST timezone name (if any). */
333 if (parse_tzname (&tz
, 1))
335 parse_offset (&tz
, 1);
336 if (*tz
== '\0' || (tz
[0] == ',' && tz
[1] == '\0'))
338 /* There is no rule. See if there is a default rule
340 __tzfile_default (tz_rules
[0].name
, tz_rules
[1].name
,
341 tz_rules
[0].offset
, tz_rules
[1].offset
);
350 /* Figure out the standard <-> DST rules. */
351 if (parse_rule (&tz
, 0))
356 /* There is no DST. */
357 tz_rules
[1].name
= tz_rules
[0].name
;
358 tz_rules
[1].offset
= tz_rules
[0].offset
;
365 /* Interpret the TZ envariable. */
367 tzset_internal (int always
)
369 static int is_initialized
;
372 if (is_initialized
&& !always
)
376 /* Examine the TZ environment variable. */
378 if (tz
&& *tz
== '\0')
379 /* User specified the empty string; use UTC explicitly. */
382 /* A leading colon means "implementation defined syntax".
383 We ignore the colon and always use the same algorithm:
384 try a data file, and if none exists parse the 1003.1 syntax. */
385 if (tz
&& *tz
== ':')
388 /* Check whether the value changed since the last run. */
389 if (old_tz
!= NULL
&& tz
!= NULL
&& strcmp (tz
, old_tz
) == 0)
390 /* No change, simply return. */
394 /* No user specification; use the site-wide default. */
397 tz_rules
[0].name
= NULL
;
398 tz_rules
[1].name
= NULL
;
400 /* Save the value of `tz'. */
402 old_tz
= tz
? __strdup (tz
) : NULL
;
404 /* Try to read a data file. */
405 __tzfile_read (tz
, 0, NULL
);
409 /* No data file found. Default to UTC if nothing specified. */
411 if (tz
== NULL
|| *tz
== '\0'
412 || (TZDEFAULT
!= NULL
&& strcmp (tz
, TZDEFAULT
) == 0))
414 memset (tz_rules
, '\0', sizeof tz_rules
);
415 tz_rules
[0].name
= tz_rules
[1].name
= "UTC";
417 tz_rules
[0].type
= tz_rules
[1].type
= J0
;
418 tz_rules
[0].change
= tz_rules
[1].change
= (time_t) -1;
423 __tzset_parse_tz (tz
);
426 /* Figure out the exact time (as a time_t) in YEAR
427 when the change described by RULE will occur and
428 put it in RULE->change, saving YEAR in RULE->computed_for. */
431 compute_change (tz_rule
*rule
, int year
)
435 if (year
!= -1 && rule
->computed_for
== year
)
436 /* Operations on times in 2 BC will be slower. Oh well. */
439 /* First set T to January 1st, 0:00:00 GMT in YEAR. */
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
;
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
))
466 Just add SECSPERDAY times the day number to the time of Jan 1st. */
467 t
+= rule
->d
* SECSPERDAY
;
471 /* Mm.n.d - Nth "Dth day" of month M. */
474 int d
, m1
, yy0
, yy1
, yy2
, dow
;
475 const unsigned short int *myday
=
476 &__mon_yday
[__isleap (year
)][rule
->m
];
478 /* First add SECSPERDAY for each day in months before M. */
479 t
+= myday
[-1] * SECSPERDAY
;
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
;
486 dow
= ((26 * m1
- 2) / 10 + 1 + yy2
+ yy2
/ 4 + yy1
/ 4 - 2 * yy1
) % 7;
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. */
495 for (i
= 1; i
< rule
->n
; ++i
)
497 if (d
+ 7 >= (int) myday
[0] - myday
[-1])
502 /* D is the day-of-month (zero-origin) of the day we want. */
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. */
511 rule
->change
= t
- rule
->offset
+ rule
->secs
;
512 rule
->computed_for
= year
;
516 /* Figure out the correct timezone for TM and set `__tzname',
517 `__timezone', and `__daylight' accordingly. */
520 __tz_compute (time_t timer
, struct tm
*tm
, int use_localtime
)
522 compute_change (&tz_rules
[0], 1900 + tm
->tm_year
);
523 compute_change (&tz_rules
[1], 1900 + tm
->tm_year
);
529 /* We have to distinguish between northern and southern
530 hemisphere. For the latter the daylight saving time
531 ends in the next year. */
532 if (__builtin_expect (tz_rules
[0].change
533 > tz_rules
[1].change
, 0))
534 isdst
= (timer
< tz_rules
[1].change
535 || timer
>= tz_rules
[0].change
);
537 isdst
= (timer
>= tz_rules
[0].change
538 && timer
< tz_rules
[1].change
);
539 tm
->tm_isdst
= isdst
;
540 tm
->tm_zone
= __tzname
[isdst
];
541 tm
->tm_gmtoff
= tz_rules
[isdst
].offset
;
545 /* Reinterpret the TZ environment variable and set `tzname'. */
551 __libc_lock_lock (tzset_lock
);
558 __tzname
[0] = (char *) tz_rules
[0].name
;
559 __tzname
[1] = (char *) tz_rules
[1].name
;
562 __libc_lock_unlock (tzset_lock
);
564 weak_alias (__tzset
, tzset
)
566 /* Return the `struct tm' representation of *TIMER in the local timezone.
567 Use local time if USE_LOCALTIME is nonzero, UTC otherwise. */
569 __tz_convert (const time_t *timer
, int use_localtime
, struct tm
*tp
)
571 long int leap_correction
;
576 __set_errno (EINVAL
);
580 __libc_lock_lock (tzset_lock
);
582 /* Update internal database according to current TZ setting.
583 POSIX.1 8.3.7.2 says that localtime_r is not required to set tzname.
584 This is a good idea since this allows at least a bit more parallelism. */
585 tzset_internal (tp
== &_tmbuf
&& use_localtime
);
588 __tzfile_compute (*timer
, use_localtime
, &leap_correction
,
589 &leap_extra_secs
, tp
);
592 if (! __offtime (timer
, 0, tp
))
595 __tz_compute (*timer
, tp
, use_localtime
);
596 leap_correction
= 0L;
600 __libc_lock_unlock (tzset_lock
);
611 if (__offtime (timer
, tp
->tm_gmtoff
- leap_correction
, tp
))
612 tp
->tm_sec
+= leap_extra_secs
;
621 libc_freeres_fn (free_mem
)
623 while (tzstring_list
!= NULL
)
625 struct tzstring_l
*old
= tzstring_list
;
627 tzstring_list
= tzstring_list
->next
;