This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
utf8.c: Reword a warning message
[perl5.git] / time64.c
CommitLineData
a272e669
MS
1/*
2
3Copyright (c) 2007-2008 Michael G Schwern
4
5This software originally derived from Paul Sheer's pivotal_gmtime_r.c.
6
7The MIT License:
8
9Permission is hereby granted, free of charge, to any person obtaining a copy
10of this software and associated documentation files (the "Software"), to deal
11in the Software without restriction, including without limitation the rights
12to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13copies of the Software, and to permit persons to whom the Software is
14furnished to do so, subject to the following conditions:
15
16The above copyright notice and this permission notice shall be included in
17all copies or substantial portions of the Software.
18
19THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25THE SOFTWARE.
26
27*/
28
29/*
30
31Programmers who have available to them 64-bit time values as a 'long
32long' type can use localtime64_r() and gmtime64_r() which correctly
33converts the time even on 32-bit systems. Whether you have 64-bit time
34values will depend on the operating system.
35
7430375d 36S_localtime64_r() is a 64-bit equivalent of localtime_r().
a272e669 37
7430375d 38S_gmtime64_r() is a 64-bit equivalent of gmtime_r().
a272e669
MS
39
40*/
41
7643e68f 42#include "time64.h"
af9b2bf5 43
a272e669
MS
44static const int days_in_month[2][12] = {
45 {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
46 {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
47};
48
49static const int julian_days_by_month[2][12] = {
50 {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334},
51 {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335},
52};
53
54static const int length_of_year[2] = { 365, 366 };
55
56/* Number of days in a 400 year Gregorian cycle */
806a119a 57static const Year years_in_gregorian_cycle = 400;
a272e669
MS
58static const int days_in_gregorian_cycle = (365 * 400) + 100 - 4 + 1;
59
60/* 28 year calendar cycle between 2010 and 2037 */
806a119a
MS
61#define SOLAR_CYCLE_LENGTH 28
62static const int safe_years[SOLAR_CYCLE_LENGTH] = {
a272e669
MS
63 2016, 2017, 2018, 2019,
64 2020, 2021, 2022, 2023,
65 2024, 2025, 2026, 2027,
66 2028, 2029, 2030, 2031,
67 2032, 2033, 2034, 2035,
68 2036, 2037, 2010, 2011,
69 2012, 2013, 2014, 2015
70};
71
ea722b76 72static const int dow_year_start[SOLAR_CYCLE_LENGTH] = {
003c3b95
MS
73 5, 0, 1, 2, /* 0 2016 - 2019 */
74 3, 5, 6, 0, /* 4 */
75 1, 3, 4, 5, /* 8 */
76 6, 1, 2, 3, /* 12 */
77 4, 6, 0, 1, /* 16 */
78 2, 4, 5, 6, /* 20 2036, 2037, 2010, 2011 */
79 0, 2, 3, 4 /* 24 2012, 2013, 2014, 2015 */
a272e669
MS
80};
81
9af24521
MS
82/* Let's assume people are going to be looking for dates in the future.
83 Let's provide some cheats so you can skip ahead.
84 This has a 4x speed boost when near 2008.
85*/
86/* Number of days since epoch on Jan 1st, 2008 GMT */
87#define CHEAT_DAYS (1199145600 / 24 / 60 / 60)
88#define CHEAT_YEARS 108
a272e669
MS
89
90#define IS_LEAP(n) ((!(((n) + 1900) % 400) || (!(((n) + 1900) % 4) && (((n) + 1900) % 100))) != 0)
91#define WRAP(a,b,m) ((a) = ((a) < 0 ) ? ((b)--, (a) + (m)) : (a))
92
b86b480f
MS
93#ifdef USE_SYSTEM_LOCALTIME
94# define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \
7bda3dfc
MS
95 (a) <= SYSTEM_LOCALTIME_MAX && \
96 (a) >= SYSTEM_LOCALTIME_MIN \
97)
b86b480f
MS
98#else
99# define SHOULD_USE_SYSTEM_LOCALTIME(a) (0)
100#endif
101
102#ifdef USE_SYSTEM_GMTIME
103# define SHOULD_USE_SYSTEM_GMTIME(a) ( \
7bda3dfc
MS
104 (a) <= SYSTEM_GMTIME_MAX && \
105 (a) >= SYSTEM_GMTIME_MIN \
106)
b86b480f
MS
107#else
108# define SHOULD_USE_SYSTEM_GMTIME(a) (0)
109#endif
a64acb40 110
d4fb0a1f 111/* Multi varadic macros are a C99 thing, alas */
461d5a49 112#ifdef TIME_64_DEBUG
7430375d
CB
113# define TIME64_TRACE(format) (fprintf(stderr, format))
114# define TIME64_TRACE1(format, var1) (fprintf(stderr, format, var1))
115# define TIME64_TRACE2(format, var1, var2) (fprintf(stderr, format, var1, var2))
116# define TIME64_TRACE3(format, var1, var2, var3) (fprintf(stderr, format, var1, var2, var3))
461d5a49 117#else
7430375d
CB
118# define TIME64_TRACE(format) ((void)0)
119# define TIME64_TRACE1(format, var1) ((void)0)
120# define TIME64_TRACE2(format, var1, var2) ((void)0)
121# define TIME64_TRACE3(format, var1, var2, var3) ((void)0)
461d5a49 122#endif
a64acb40 123
7430375d 124static int S_is_exception_century(Year year)
a272e669
MS
125{
126 int is_exception = ((year % 100 == 0) && !(year % 400 == 0));
7430375d 127 TIME64_TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no");
a272e669
MS
128
129 return(is_exception);
130}
131
9af24521 132
7430375d 133static Time64_T S_timegm64(struct TM *date) {
b86b480f
MS
134 int days = 0;
135 Time64_T seconds = 0;
136 Year year;
a272e669 137
9af24521
MS
138 if( date->tm_year > 70 ) {
139 year = 70;
140 while( year < date->tm_year ) {
141 days += length_of_year[IS_LEAP(year)];
142 year++;
a272e669
MS
143 }
144 }
9af24521
MS
145 else if ( date->tm_year < 70 ) {
146 year = 69;
147 do {
148 days -= length_of_year[IS_LEAP(year)];
149 year--;
150 } while( year >= date->tm_year );
151 }
152
153 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon];
154 days += date->tm_mday - 1;
155
ea722b76
MS
156 /* Avoid overflowing the days integer */
157 seconds = days;
158 seconds = seconds * 60 * 60 * 24;
159
9af24521
MS
160 seconds += date->tm_hour * 60 * 60;
161 seconds += date->tm_min * 60;
162 seconds += date->tm_sec;
163
b86b480f 164 return(seconds);
9af24521
MS
165}
166
167
554fcfb9 168#ifdef DEBUGGING
7430375d 169static int S_check_tm(struct TM *tm)
9af24521 170{
9af24521 171 /* Don't forget leap seconds */
af9b2bf5 172 assert(tm->tm_sec >= 0);
9af24521
MS
173 assert(tm->tm_sec <= 61);
174
af9b2bf5 175 assert(tm->tm_min >= 0);
9af24521
MS
176 assert(tm->tm_min <= 59);
177
178 assert(tm->tm_hour >= 0);
179 assert(tm->tm_hour <= 23);
180
181 assert(tm->tm_mday >= 1);
af9b2bf5 182 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]);
9af24521
MS
183
184 assert(tm->tm_mon >= 0);
185 assert(tm->tm_mon <= 11);
186
187 assert(tm->tm_wday >= 0);
188 assert(tm->tm_wday <= 6);
189
190 assert(tm->tm_yday >= 0);
af9b2bf5 191 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]);
9af24521
MS
192
193#ifdef HAS_TM_TM_GMTOFF
194 assert(tm->tm_gmtoff >= -24 * 60 * 60);
195 assert(tm->tm_gmtoff <= 24 * 60 * 60);
196#endif
af9b2bf5
MS
197
198 return 1;
a272e669 199}
554fcfb9 200#endif
a64acb40 201
a272e669
MS
202
203/* The exceptional centuries without leap years cause the cycle to
204 shift by 16
205*/
7430375d 206static Year S_cycle_offset(Year year)
a272e669 207{
750c447b
MS
208 const Year start_year = 2000;
209 Year year_diff = year - start_year;
210 Year exceptions;
003c3b95
MS
211
212 if( year > start_year )
213 year_diff--;
214
750c447b
MS
215 exceptions = year_diff / 100;
216 exceptions -= year_diff / 400;
a272e669 217
7430375d 218 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n",
461d5a49 219 year, exceptions, year_diff);
a272e669
MS
220
221 return exceptions * 16;
222}
223
224/* For a given year after 2038, pick the latest possible matching
225 year in the 28 year calendar cycle.
ea722b76
MS
226
227 A matching year...
228 1) Starts on the same day of the week.
229 2) Has the same leap year status.
230
231 This is so the calendars match up.
232
233 Also the previous year must match. When doing Jan 1st you might
234 wind up on Dec 31st the previous year when doing a -UTC time zone.
003c3b95
MS
235
236 Finally, the next year must have the same start day of week. This
237 is for Dec 31st with a +UTC time zone.
238 It doesn't need the same leap year status since we only care about
239 January 1st.
a272e669 240*/
7430375d 241static int S_safe_year(Year year)
a272e669
MS
242{
243 int safe_year;
7430375d 244 Year year_cycle = year + S_cycle_offset(year);
a272e669
MS
245
246 /* Change non-leap xx00 years to an equivalent */
7430375d 247 if( S_is_exception_century(year) )
a272e669
MS
248 year_cycle += 11;
249
003c3b95 250 /* Also xx01 years, since the previous year will be wrong */
7430375d 251 if( S_is_exception_century(year - 1) )
003c3b95
MS
252 year_cycle += 17;
253
a272e669 254 year_cycle %= SOLAR_CYCLE_LENGTH;
ea722b76
MS
255 if( year_cycle < 0 )
256 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle;
a272e669 257
003c3b95
MS
258 assert( year_cycle >= 0 );
259 assert( year_cycle < SOLAR_CYCLE_LENGTH );
a272e669
MS
260 safe_year = safe_years[year_cycle];
261
262 assert(safe_year <= 2037 && safe_year >= 2010);
263
7430375d 264 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n",
461d5a49 265 year, year_cycle, safe_year);
a272e669
MS
266
267 return safe_year;
268}
269
750c447b 270
7430375d 271static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) {
806a119a
MS
272 if( src == NULL ) {
273 memset(dest, 0, sizeof(*dest));
274 }
275 else {
276# ifdef USE_TM64
277 dest->tm_sec = src->tm_sec;
278 dest->tm_min = src->tm_min;
279 dest->tm_hour = src->tm_hour;
280 dest->tm_mday = src->tm_mday;
281 dest->tm_mon = src->tm_mon;
282 dest->tm_year = (Year)src->tm_year;
806a119a
MS
283 dest->tm_wday = src->tm_wday;
284 dest->tm_yday = src->tm_yday;
285 dest->tm_isdst = src->tm_isdst;
286
287# ifdef HAS_TM_TM_GMTOFF
288 dest->tm_gmtoff = src->tm_gmtoff;
289# endif
290
291# ifdef HAS_TM_TM_ZONE
292 dest->tm_zone = src->tm_zone;
293# endif
294
295# else
296 /* They're the same type */
297 memcpy(dest, src, sizeof(*dest));
298# endif
299 }
300}
301
302
7430375d 303#ifndef HAS_LOCALTIME_R
948ea7a9 304/* Simulate localtime_r() to the best of our ability */
7430375d 305static struct tm * S_localtime_r(const time_t *clock, struct tm *result) {
dbf7dff6 306#ifdef VMS
478780ab 307 dTHX; /* in case the following is defined as Perl_my_localtime(aTHX_ ...) */
dbf7dff6 308#endif
948ea7a9
MS
309 const struct tm *static_result = localtime(clock);
310
311 assert(result != NULL);
312
313 if( static_result == NULL ) {
314 memset(result, 0, sizeof(*result));
315 return NULL;
316 }
317 else {
318 memcpy(result, static_result, sizeof(*result));
319 return result;
320 }
321}
7430375d 322#endif
948ea7a9 323
7430375d 324#ifndef HAS_GMTIME_R
948ea7a9 325/* Simulate gmtime_r() to the best of our ability */
7430375d 326static struct tm * S_gmtime_r(const time_t *clock, struct tm *result) {
478780ab 327 dTHX; /* in case the following is defined as Perl_my_gmtime(aTHX_ ...) */
948ea7a9
MS
328 const struct tm *static_result = gmtime(clock);
329
330 assert(result != NULL);
331
332 if( static_result == NULL ) {
333 memset(result, 0, sizeof(*result));
334 return NULL;
335 }
336 else {
337 memcpy(result, static_result, sizeof(*result));
338 return result;
339 }
340}
7430375d 341#endif
948ea7a9 342
7430375d 343static struct TM *S_gmtime64_r (const Time64_T *in_time, struct TM *p)
a272e669
MS
344{
345 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday;
b86b480f 346 Time64_T v_tm_tday;
a272e669 347 int leap;
b86b480f 348 Time64_T m;
a272e669 349 Time64_T time = *in_time;
750c447b 350 Year year = 70;
806a119a 351 int cycles = 0;
a272e669 352
948ea7a9
MS
353 assert(p != NULL);
354
a64acb40
MS
355 /* Use the system gmtime() if time_t is small enough */
356 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) {
cd1759d8 357 time_t safe_time = (time_t)*in_time;
806a119a
MS
358 struct tm safe_date;
359 GMTIME_R(&safe_time, &safe_date);
360
7430375d
CB
361 S_copy_little_tm_to_big_TM(&safe_date, p);
362 assert(S_check_tm(p));
806a119a 363
a64acb40
MS
364 return p;
365 }
366
9af24521 367#ifdef HAS_TM_TM_GMTOFF
a272e669
MS
368 p->tm_gmtoff = 0;
369#endif
370 p->tm_isdst = 0;
371
9af24521 372#ifdef HAS_TM_TM_ZONE
1cefca6b 373 p->tm_zone = (char *)"UTC";
a272e669
MS
374#endif
375
d95a2ea5
CB
376 v_tm_sec = (int)fmod(time, 60.0);
377 time = time >= 0 ? floor(time / 60.0) : ceil(time / 60.0);
378 v_tm_min = (int)fmod(time, 60.0);
379 time = time >= 0 ? floor(time / 60.0) : ceil(time / 60.0);
380 v_tm_hour = (int)fmod(time, 24.0);
381 time = time >= 0 ? floor(time / 24.0) : ceil(time / 24.0);
455f2c6c 382 v_tm_tday = time;
750c447b 383
a272e669
MS
384 WRAP (v_tm_sec, v_tm_min, 60);
385 WRAP (v_tm_min, v_tm_hour, 60);
386 WRAP (v_tm_hour, v_tm_tday, 24);
750c447b 387
d95a2ea5 388 v_tm_wday = (int)fmod((v_tm_tday + 4.0), 7.0);
750c447b 389 if (v_tm_wday < 0)
a272e669
MS
390 v_tm_wday += 7;
391 m = v_tm_tday;
a272e669 392
9af24521
MS
393 if (m >= CHEAT_DAYS) {
394 year = CHEAT_YEARS;
395 m -= CHEAT_DAYS;
396 }
397
398 if (m >= 0) {
a272e669 399 /* Gregorian cycles, this is huge optimization for distant times */
d95a2ea5 400 cycles = (int)floor(m / (Time64_T) days_in_gregorian_cycle);
806a119a
MS
401 if( cycles ) {
402 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
403 year += (cycles * years_in_gregorian_cycle);
a272e669
MS
404 }
405
406 /* Years */
407 leap = IS_LEAP (year);
408 while (m >= (Time64_T) length_of_year[leap]) {
409 m -= (Time64_T) length_of_year[leap];
410 year++;
411 leap = IS_LEAP (year);
412 }
413
414 /* Months */
415 v_tm_mon = 0;
416 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) {
417 m -= (Time64_T) days_in_month[leap][v_tm_mon];
418 v_tm_mon++;
419 }
420 } else {
9af24521 421 year--;
a272e669
MS
422
423 /* Gregorian cycles */
d95a2ea5 424 cycles = (int)ceil((m / (Time64_T) days_in_gregorian_cycle) + 1);
806a119a
MS
425 if( cycles ) {
426 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
427 year += (cycles * years_in_gregorian_cycle);
a272e669
MS
428 }
429
430 /* Years */
431 leap = IS_LEAP (year);
432 while (m < (Time64_T) -length_of_year[leap]) {
433 m += (Time64_T) length_of_year[leap];
434 year--;
435 leap = IS_LEAP (year);
436 }
437
438 /* Months */
439 v_tm_mon = 11;
440 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) {
441 m += (Time64_T) days_in_month[leap][v_tm_mon];
442 v_tm_mon--;
443 }
444 m += (Time64_T) days_in_month[leap][v_tm_mon];
445 }
446
447 p->tm_year = year;
448 if( p->tm_year != year ) {
9af24521 449#ifdef EOVERFLOW
a272e669 450 errno = EOVERFLOW;
9af24521 451#endif
a272e669
MS
452 return NULL;
453 }
454
b86b480f 455 /* At this point m is less than a year so casting to an int is safe */
a272e669 456 p->tm_mday = (int) m + 1;
b86b480f
MS
457 p->tm_yday = julian_days_by_month[leap][v_tm_mon] + (int)m;
458 p->tm_sec = v_tm_sec;
459 p->tm_min = v_tm_min;
460 p->tm_hour = v_tm_hour;
461 p->tm_mon = v_tm_mon;
462 p->tm_wday = v_tm_wday;
a272e669 463
7430375d 464 assert(S_check_tm(p));
a272e669
MS
465
466 return p;
467}
468
469
673062a9 470static struct TM *S_localtime64_r (const Time64_T *time, struct TM *local_tm)
a272e669
MS
471{
472 time_t safe_time;
806a119a
MS
473 struct tm safe_date;
474 struct TM gm_tm;
750c447b 475 Year orig_year;
a272e669
MS
476 int month_diff;
477
948ea7a9
MS
478 assert(local_tm != NULL);
479
a64acb40
MS
480 /* Use the system localtime() if time_t is small enough */
481 if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) {
cd1759d8 482 safe_time = (time_t)*time;
806a119a 483
7430375d 484 TIME64_TRACE1("Using system localtime for %lld\n", *time);
461d5a49 485
806a119a
MS
486 LOCALTIME_R(&safe_time, &safe_date);
487
7430375d
CB
488 S_copy_little_tm_to_big_TM(&safe_date, local_tm);
489 assert(S_check_tm(local_tm));
806a119a 490
a64acb40
MS
491 return local_tm;
492 }
493
7430375d
CB
494 if( S_gmtime64_r(time, &gm_tm) == NULL ) {
495 TIME64_TRACE1("gmtime64_r returned null for %lld\n", *time);
af832814 496 return NULL;
461d5a49 497 }
af832814 498
a272e669
MS
499 orig_year = gm_tm.tm_year;
500
c07fe26c 501 if (gm_tm.tm_year > (2037 - 1900) ||
461d5a49 502 gm_tm.tm_year < (1970 - 1900)
c07fe26c
MS
503 )
504 {
7430375d
CB
505 TIME64_TRACE1("Mapping tm_year %lld to safe_year\n", (Year)gm_tm.tm_year);
506 gm_tm.tm_year = S_safe_year((Year)(gm_tm.tm_year + 1900)) - 1900;
c07fe26c 507 }
a272e669 508
7430375d 509 safe_time = (time_t)S_timegm64(&gm_tm);
461d5a49 510 if( LOCALTIME_R(&safe_time, &safe_date) == NULL ) {
7430375d 511 TIME64_TRACE1("localtime_r(%d) returned NULL\n", (int)safe_time);
af832814 512 return NULL;
461d5a49 513 }
a272e669 514
7430375d 515 S_copy_little_tm_to_big_TM(&safe_date, local_tm);
806a119a 516
a272e669 517 local_tm->tm_year = orig_year;
af832814 518 if( local_tm->tm_year != orig_year ) {
7430375d 519 TIME64_TRACE2("tm_year overflow: tm_year %lld, orig_year %lld\n",
461d5a49
MS
520 (Year)local_tm->tm_year, (Year)orig_year);
521
af832814
MS
522#ifdef EOVERFLOW
523 errno = EOVERFLOW;
524#endif
525 return NULL;
526 }
527
528
a272e669
MS
529 month_diff = local_tm->tm_mon - gm_tm.tm_mon;
530
531 /* When localtime is Dec 31st previous year and
532 gmtime is Jan 1st next year.
533 */
534 if( month_diff == 11 ) {
535 local_tm->tm_year--;
536 }
537
538 /* When localtime is Jan 1st, next year and
539 gmtime is Dec 31st, previous year.
540 */
541 if( month_diff == -11 ) {
542 local_tm->tm_year++;
543 }
544
545 /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st
546 in a non-leap xx00. There is one point in the cycle
547 we can't account for which the safe xx00 year is a leap
486ec47a 548 year. So we need to correct for Dec 31st coming out as
a272e669
MS
549 the 366th day of the year.
550 */
551 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 )
552 local_tm->tm_yday--;
553
7430375d 554 assert(S_check_tm(local_tm));
a272e669
MS
555
556 return local_tm;
557}