3 Copyright (c) 2007-2008 Michael G Schwern
5 This software originally derived from Paul Sheer's pivotal_gmtime_r.c.
9 Permission is hereby granted, free of charge, to any person obtaining a copy
10 of this software and associated documentation files (the "Software"), to deal
11 in the Software without restriction, including without limitation the rights
12 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 copies of the Software, and to permit persons to whom the Software is
14 furnished to do so, subject to the following conditions:
16 The above copyright notice and this permission notice shall be included in
17 all copies or substantial portions of the Software.
19 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
31 Programmers who have available to them 64-bit time values as a 'long
32 long' type can use localtime64_r() and gmtime64_r() which correctly
33 converts the time even on 32-bit systems. Whether you have 64-bit time
34 values will depend on the operating system.
36 Perl_localtime64_r() is a 64-bit equivalent of localtime_r().
38 Perl_gmtime64_r() is a 64-bit equivalent of gmtime_r().
43 #define PERL_IN_TIME64_C
47 static const char days_in_month[2][12] = {
48 {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
49 {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
52 static const short julian_days_by_month[2][12] = {
53 {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334},
54 {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335},
57 static const short length_of_year[2] = { 365, 366 };
59 /* Number of days in a 400 year Gregorian cycle */
60 static const Year years_in_gregorian_cycle = 400;
61 static const int days_in_gregorian_cycle = (365 * 400) + 100 - 4 + 1;
63 /* 28 year calendar cycle between 2010 and 2037 */
64 #define SOLAR_CYCLE_LENGTH 28
65 static const short safe_years[SOLAR_CYCLE_LENGTH] = {
66 2016, 2017, 2018, 2019,
67 2020, 2021, 2022, 2023,
68 2024, 2025, 2026, 2027,
69 2028, 2029, 2030, 2031,
70 2032, 2033, 2034, 2035,
71 2036, 2037, 2010, 2011,
72 2012, 2013, 2014, 2015
75 /* Let's assume people are going to be looking for dates in the future.
76 Let's provide some cheats so you can skip ahead.
77 This has a 4x speed boost when near 2008.
79 /* Number of days since epoch on Jan 1st, 2008 GMT */
80 #define CHEAT_DAYS (1199145600 / 24 / 60 / 60)
81 #define CHEAT_YEARS 108
83 #define IS_LEAP(n) ((!(((n) + 1900) % 400) || (!(((n) + 1900) % 4) && (((n) + 1900) % 100))) != 0)
84 #undef WRAP /* some <termios.h> define this */
85 #define WRAP(a,b,m) ((a) = ((a) < 0 ) ? ((b)--, (a) + (m)) : (a))
87 #ifdef USE_SYSTEM_LOCALTIME
88 # define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \
89 (a) <= SYSTEM_LOCALTIME_MAX && \
90 (a) >= SYSTEM_LOCALTIME_MIN \
93 # define SHOULD_USE_SYSTEM_LOCALTIME(a) (0)
96 #ifdef USE_SYSTEM_GMTIME
97 # define SHOULD_USE_SYSTEM_GMTIME(a) ( \
98 (a) <= SYSTEM_GMTIME_MAX && \
99 (a) >= SYSTEM_GMTIME_MIN \
102 # define SHOULD_USE_SYSTEM_GMTIME(a) (0)
105 /* Multi varadic macros are a C99 thing, alas */
107 # define TIME64_TRACE(format) (fprintf(stderr, format))
108 # define TIME64_TRACE1(format, var1) (fprintf(stderr, format, var1))
109 # define TIME64_TRACE2(format, var1, var2) (fprintf(stderr, format, var1, var2))
110 # define TIME64_TRACE3(format, var1, var2, var3) (fprintf(stderr, format, var1, var2, var3))
112 # define TIME64_TRACE(format) ((void)0)
113 # define TIME64_TRACE1(format, var1) ((void)0)
114 # define TIME64_TRACE2(format, var1, var2) ((void)0)
115 # define TIME64_TRACE3(format, var1, var2, var3) ((void)0)
118 /* Set up the mutexes for this file. There are no races possible on
119 * non-threaded perls, nor platforms that naturally don't have them.
120 * Otherwise, we need to have mutexes. If we have reentrant versions of the
121 * functions below, they automatically will be substituted for the
122 * non-reentrant ones. That solves the problem of the buffers being trashed by
123 * another thread, but not of the environment or locale changing during their
124 * execution. To do that, we only need a read lock (which prevents writing by
125 * others). However, if we don't have re-entrant functions, we can gain some
126 * measure of thread-safety by using an exclusive lock during their execution.
127 * That will protect against any other use of the functions that use the
128 * mutexes, which all of core should be using. */
129 #ifdef USE_REENTRANT_API /* This indicates a platform where we need reentrant
130 versions if have them */
131 # ifdef PERL_REENTR_USING_LOCALTIME_R
132 # define LOCALTIME_LOCK ENV_LOCALE_READ_LOCK
133 # define LOCALTIME_UNLOCK ENV_LOCALE_READ_UNLOCK
135 # define LOCALTIME_LOCK ENV_LOCALE_LOCK
136 # define LOCALTIME_UNLOCK ENV_LOCALE_UNLOCK
138 # ifdef PERL_REENTR_USING_GMTIME_R
139 # define GMTIME_LOCK ENV_LOCALE_READ_LOCK
140 # define GMTIME_UNLOCK ENV_LOCALE_READ_UNLOCK
142 # define GMTIME_LOCK ENV_LOCALE_LOCK
143 # define GMTIME_UNLOCK ENV_LOCALE_UNLOCK
145 #else /* Reentrant not needed, so races not possible */
146 # define LOCALTIME_LOCK NOOP
147 # define LOCALTIME_UNLOCK NOOP
148 # define GMTIME_LOCK NOOP
149 # define GMTIME_UNLOCK NOOP
152 static int S_is_exception_century(Year year)
154 const int is_exception = ((year % 100 == 0) && !(year % 400 == 0));
155 TIME64_TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no");
157 return(is_exception);
161 static Time64_T S_timegm64(const struct TM *date) {
163 Time64_T seconds = 0;
165 if( date->tm_year > 70 ) {
167 while( year < date->tm_year ) {
168 days += length_of_year[IS_LEAP(year)];
172 else if ( date->tm_year < 70 ) {
175 days -= length_of_year[IS_LEAP(year)];
177 } while( year >= date->tm_year );
180 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon];
181 days += date->tm_mday - 1;
183 /* Avoid overflowing the days integer */
185 seconds = seconds * 60 * 60 * 24;
187 seconds += date->tm_hour * 60 * 60;
188 seconds += date->tm_min * 60;
189 seconds += date->tm_sec;
196 static int S_check_tm(const struct TM *tm)
198 /* Don't forget leap seconds */
199 assert(tm->tm_sec >= 0);
200 assert(tm->tm_sec <= 61);
202 assert(tm->tm_min >= 0);
203 assert(tm->tm_min <= 59);
205 assert(tm->tm_hour >= 0);
206 assert(tm->tm_hour <= 23);
208 assert(tm->tm_mday >= 1);
209 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]);
211 assert(tm->tm_mon >= 0);
212 assert(tm->tm_mon <= 11);
214 assert(tm->tm_wday >= 0);
215 assert(tm->tm_wday <= 6);
217 assert(tm->tm_yday >= 0);
218 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]);
220 #ifdef HAS_TM_TM_GMTOFF
221 assert(tm->tm_gmtoff >= -24 * 60 * 60);
222 assert(tm->tm_gmtoff <= 24 * 60 * 60);
230 /* The exceptional centuries without leap years cause the cycle to
233 static Year S_cycle_offset(Year year)
235 const Year start_year = 2000;
236 Year year_diff = year - start_year;
239 if( year > start_year )
242 exceptions = year_diff / 100;
243 exceptions -= year_diff / 400;
245 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n",
246 year, exceptions, year_diff);
248 return exceptions * 16;
251 /* For a given year after 2038, pick the latest possible matching
252 year in the 28 year calendar cycle.
255 1) Starts on the same day of the week.
256 2) Has the same leap year status.
258 This is so the calendars match up.
260 Also the previous year must match. When doing Jan 1st you might
261 wind up on Dec 31st the previous year when doing a -UTC time zone.
263 Finally, the next year must have the same start day of week. This
264 is for Dec 31st with a +UTC time zone.
265 It doesn't need the same leap year status since we only care about
268 static int S_safe_year(Year year)
271 Year year_cycle = year + S_cycle_offset(year);
273 /* Change non-leap xx00 years to an equivalent */
274 if( S_is_exception_century(year) )
277 /* Also xx01 years, since the previous year will be wrong */
278 if( S_is_exception_century(year - 1) )
281 year_cycle %= SOLAR_CYCLE_LENGTH;
283 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle;
285 assert( year_cycle >= 0 );
286 assert( year_cycle < SOLAR_CYCLE_LENGTH );
287 safe_year = safe_years[year_cycle];
289 assert(safe_year <= 2037 && safe_year >= 2010);
291 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n",
292 year, year_cycle, safe_year);
298 static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) {
302 dest->tm_sec = src->tm_sec;
303 dest->tm_min = src->tm_min;
304 dest->tm_hour = src->tm_hour;
305 dest->tm_mday = src->tm_mday;
306 dest->tm_mon = src->tm_mon;
307 dest->tm_year = (Year)src->tm_year;
308 dest->tm_wday = src->tm_wday;
309 dest->tm_yday = src->tm_yday;
310 dest->tm_isdst = src->tm_isdst;
312 # ifdef HAS_TM_TM_GMTOFF
313 dest->tm_gmtoff = src->tm_gmtoff;
316 # ifdef HAS_TM_TM_ZONE
317 dest->tm_zone = src->tm_zone;
321 /* They're the same type */
322 memcpy(dest, src, sizeof(*dest));
326 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p)
328 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday;
332 Time64_T time = *in_time;
338 /* Use the system gmtime() if time_t is small enough */
339 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) {
340 time_t safe_time = (time_t)*in_time;
346 /* reentr.h will automatically replace this with a call to gmtime_r()
347 * when appropriate */
348 result = gmtime(&safe_time);
350 assert(result != NULL);
352 #if defined(HAS_GMTIME_R) && defined(USE_REENTRANT_API)
354 PERL_UNUSED_VAR(safe_date);
356 /* Here, no gmtime_r() and is a threaded perl where the result can be
357 * overwritten by a call in another thread. Copy to a safe place,
358 * hopefully before another gmtime that isn't using the mutexes can
359 * jump in and trash this result. */
360 memcpy(&safe_date, result, sizeof(safe_date));
365 S_copy_little_tm_to_big_TM(result, p);
366 assert(S_check_tm(p));
371 #ifdef HAS_TM_TM_GMTOFF
376 #ifdef HAS_TM_TM_ZONE
377 p->tm_zone = (char *)"UTC";
380 v_tm_sec = (int)Perl_fmod(time, 60.0);
381 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0);
382 v_tm_min = (int)Perl_fmod(time, 60.0);
383 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0);
384 v_tm_hour = (int)Perl_fmod(time, 24.0);
385 time = time >= 0 ? Perl_floor(time / 24.0) : Perl_ceil(time / 24.0);
388 WRAP (v_tm_sec, v_tm_min, 60);
389 WRAP (v_tm_min, v_tm_hour, 60);
390 WRAP (v_tm_hour, v_tm_tday, 24);
392 v_tm_wday = (int)Perl_fmod((v_tm_tday + 4.0), 7.0);
397 if (m >= CHEAT_DAYS) {
403 /* Gregorian cycles, this is huge optimization for distant times */
404 const int cycles = (int)Perl_floor(m / (Time64_T) days_in_gregorian_cycle);
406 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
407 year += (cycles * years_in_gregorian_cycle);
411 leap = IS_LEAP (year);
412 while (m >= (Time64_T) length_of_year[leap]) {
413 m -= (Time64_T) length_of_year[leap];
415 leap = IS_LEAP (year);
420 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) {
421 m -= (Time64_T) days_in_month[leap][v_tm_mon];
429 /* Gregorian cycles */
430 cycles = (int)Perl_ceil((m / (Time64_T) days_in_gregorian_cycle) + 1);
432 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
433 year += (cycles * years_in_gregorian_cycle);
437 leap = IS_LEAP (year);
438 while (m < (Time64_T) -length_of_year[leap]) {
439 m += (Time64_T) length_of_year[leap];
441 leap = IS_LEAP (year);
446 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) {
447 m += (Time64_T) days_in_month[leap][v_tm_mon];
450 m += (Time64_T) days_in_month[leap][v_tm_mon];
454 if( p->tm_year != year ) {
461 /* At this point m is less than a year so casting to an int is safe */
462 p->tm_mday = (int) m + 1;
463 p->tm_yday = julian_days_by_month[leap][v_tm_mon] + (int)m;
464 p->tm_sec = v_tm_sec;
465 p->tm_min = v_tm_min;
466 p->tm_hour = v_tm_hour;
467 p->tm_mon = v_tm_mon;
468 p->tm_wday = v_tm_wday;
470 assert(S_check_tm(p));
476 struct TM *Perl_localtime64_r (const Time64_T *time, struct TM *local_tm)
480 const struct tm * result;
484 const bool use_system = SHOULD_USE_SYSTEM_LOCALTIME(*time);
487 assert(local_tm != NULL);
489 /* Use the system localtime() if time_t is small enough */
491 safe_time = (time_t)*time;
493 TIME64_TRACE1("Using system localtime for %lld\n", *time);
496 if (Perl_gmtime64_r(time, &gm_tm) == NULL) {
497 TIME64_TRACE1("gmtime64_r returned null for %lld\n", *time);
501 orig_year = gm_tm.tm_year;
503 if (gm_tm.tm_year > (2037 - 1900) ||
504 gm_tm.tm_year < (1970 - 1900)
507 TIME64_TRACE1("Mapping tm_year %lld to safe_year\n",
508 (Year)gm_tm.tm_year);
509 gm_tm.tm_year = S_safe_year((Year)(gm_tm.tm_year + 1900)) - 1900;
512 safe_time = (time_t)S_timegm64(&gm_tm);
517 /* reentr.h will automatically replace this with a call to localtime_r()
518 * when appropriate */
519 result = localtime(&safe_time);
521 if(UNLIKELY(result == NULL)) {
523 TIME64_TRACE1("localtime(%d) returned NULL\n", (int)safe_time);
527 #if ! defined(USE_REENTRANT_API) || defined(PERL_REENTR_USING_LOCALTIME_R)
529 PERL_UNUSED_VAR(safe_date);
533 /* Here, would be using localtime_r() if it could, meaning there isn't one,
534 * and is a threaded perl where the result can be overwritten by a call in
535 * another thread. Copy to a safe place, hopefully before another
536 * localtime that isn't using the mutexes can jump in and trash this
538 memcpy(&safe_date, result, sizeof(safe_date));
545 S_copy_little_tm_to_big_TM(result, local_tm);
549 local_tm->tm_year = orig_year;
550 if( local_tm->tm_year != orig_year ) {
551 TIME64_TRACE2("tm_year overflow: tm_year %lld, orig_year %lld\n",
552 (Year)local_tm->tm_year, (Year)orig_year);
560 month_diff = local_tm->tm_mon - gm_tm.tm_mon;
562 /* When localtime is Dec 31st previous year and
563 gmtime is Jan 1st next year.
565 if( month_diff == 11 ) {
569 /* When localtime is Jan 1st, next year and
570 gmtime is Dec 31st, previous year.
572 if( month_diff == -11 ) {
576 /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st
577 in a non-leap xx00. There is one point in the cycle
578 we can't account for which the safe xx00 year is a leap
579 year. So we need to correct for Dec 31st coming out as
580 the 366th day of the year.
582 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 )
587 assert(S_check_tm(local_tm));