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 static int S_is_exception_century(Year year)
120 const int is_exception = ((year % 100 == 0) && !(year % 400 == 0));
121 TIME64_TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no");
123 return(is_exception);
127 static Time64_T S_timegm64(const struct TM *date) {
129 Time64_T seconds = 0;
131 if( date->tm_year > 70 ) {
133 while( year < date->tm_year ) {
134 days += length_of_year[IS_LEAP(year)];
138 else if ( date->tm_year < 70 ) {
141 days -= length_of_year[IS_LEAP(year)];
143 } while( year >= date->tm_year );
146 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon];
147 days += date->tm_mday - 1;
149 /* Avoid overflowing the days integer */
151 seconds = seconds * 60 * 60 * 24;
153 seconds += date->tm_hour * 60 * 60;
154 seconds += date->tm_min * 60;
155 seconds += date->tm_sec;
162 static int S_check_tm(const struct TM *tm)
164 /* Don't forget leap seconds */
165 assert(tm->tm_sec >= 0);
166 assert(tm->tm_sec <= 61);
168 assert(tm->tm_min >= 0);
169 assert(tm->tm_min <= 59);
171 assert(tm->tm_hour >= 0);
172 assert(tm->tm_hour <= 23);
174 assert(tm->tm_mday >= 1);
175 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]);
177 assert(tm->tm_mon >= 0);
178 assert(tm->tm_mon <= 11);
180 assert(tm->tm_wday >= 0);
181 assert(tm->tm_wday <= 6);
183 assert(tm->tm_yday >= 0);
184 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]);
186 #ifdef HAS_TM_TM_GMTOFF
187 assert(tm->tm_gmtoff >= -24 * 60 * 60);
188 assert(tm->tm_gmtoff <= 24 * 60 * 60);
196 /* The exceptional centuries without leap years cause the cycle to
199 static Year S_cycle_offset(Year year)
201 const Year start_year = 2000;
202 Year year_diff = year - start_year;
205 if( year > start_year )
208 exceptions = year_diff / 100;
209 exceptions -= year_diff / 400;
211 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n",
212 year, exceptions, year_diff);
214 return exceptions * 16;
217 /* For a given year after 2038, pick the latest possible matching
218 year in the 28 year calendar cycle.
221 1) Starts on the same day of the week.
222 2) Has the same leap year status.
224 This is so the calendars match up.
226 Also the previous year must match. When doing Jan 1st you might
227 wind up on Dec 31st the previous year when doing a -UTC time zone.
229 Finally, the next year must have the same start day of week. This
230 is for Dec 31st with a +UTC time zone.
231 It doesn't need the same leap year status since we only care about
234 static int S_safe_year(Year year)
237 Year year_cycle = year + S_cycle_offset(year);
239 /* Change non-leap xx00 years to an equivalent */
240 if( S_is_exception_century(year) )
243 /* Also xx01 years, since the previous year will be wrong */
244 if( S_is_exception_century(year - 1) )
247 year_cycle %= SOLAR_CYCLE_LENGTH;
249 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle;
251 assert( year_cycle >= 0 );
252 assert( year_cycle < SOLAR_CYCLE_LENGTH );
253 safe_year = safe_years[year_cycle];
255 assert(safe_year <= 2037 && safe_year >= 2010);
257 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n",
258 year, year_cycle, safe_year);
264 static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) {
268 dest->tm_sec = src->tm_sec;
269 dest->tm_min = src->tm_min;
270 dest->tm_hour = src->tm_hour;
271 dest->tm_mday = src->tm_mday;
272 dest->tm_mon = src->tm_mon;
273 dest->tm_year = (Year)src->tm_year;
274 dest->tm_wday = src->tm_wday;
275 dest->tm_yday = src->tm_yday;
276 dest->tm_isdst = src->tm_isdst;
278 # ifdef HAS_TM_TM_GMTOFF
279 dest->tm_gmtoff = src->tm_gmtoff;
282 # ifdef HAS_TM_TM_ZONE
283 dest->tm_zone = src->tm_zone;
287 /* They're the same type */
288 memcpy(dest, src, sizeof(*dest));
293 #ifndef HAS_LOCALTIME_R
294 /* Simulate localtime_r() to the best of our ability */
295 static struct tm * S_localtime_r(const time_t *clock, struct tm *result) {
297 dTHX; /* the following is defined as Perl_my_localtime(aTHX_ ...) */
299 const struct tm * const static_result = localtime(clock);
301 assert(result != NULL);
303 if( static_result == NULL ) {
304 memset(result, 0, sizeof(*result));
308 memcpy(result, static_result, sizeof(*result));
315 /* Simulate gmtime_r() to the best of our ability */
316 static struct tm * S_gmtime_r(const time_t *clock, struct tm *result) {
318 dTHX; /* the following is defined as Perl_my_localtime(aTHX_ ...) */
320 const struct tm * const static_result = gmtime(clock);
322 assert(result != NULL);
324 if( static_result == NULL ) {
325 memset(result, 0, sizeof(*result));
329 memcpy(result, static_result, sizeof(*result));
335 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p)
337 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday;
341 Time64_T time = *in_time;
346 /* Use the system gmtime() if time_t is small enough */
347 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) {
348 time_t safe_time = (time_t)*in_time;
350 GMTIME_R(&safe_time, &safe_date);
352 S_copy_little_tm_to_big_TM(&safe_date, p);
353 assert(S_check_tm(p));
358 #ifdef HAS_TM_TM_GMTOFF
363 #ifdef HAS_TM_TM_ZONE
364 p->tm_zone = (char *)"UTC";
367 v_tm_sec = (int)Perl_fmod(time, 60.0);
368 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0);
369 v_tm_min = (int)Perl_fmod(time, 60.0);
370 time = time >= 0 ? Perl_floor(time / 60.0) : Perl_ceil(time / 60.0);
371 v_tm_hour = (int)Perl_fmod(time, 24.0);
372 time = time >= 0 ? Perl_floor(time / 24.0) : Perl_ceil(time / 24.0);
375 WRAP (v_tm_sec, v_tm_min, 60);
376 WRAP (v_tm_min, v_tm_hour, 60);
377 WRAP (v_tm_hour, v_tm_tday, 24);
379 v_tm_wday = (int)Perl_fmod((v_tm_tday + 4.0), 7.0);
384 if (m >= CHEAT_DAYS) {
390 /* Gregorian cycles, this is huge optimization for distant times */
391 const int cycles = (int)Perl_floor(m / (Time64_T) days_in_gregorian_cycle);
393 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
394 year += (cycles * years_in_gregorian_cycle);
398 leap = IS_LEAP (year);
399 while (m >= (Time64_T) length_of_year[leap]) {
400 m -= (Time64_T) length_of_year[leap];
402 leap = IS_LEAP (year);
407 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) {
408 m -= (Time64_T) days_in_month[leap][v_tm_mon];
416 /* Gregorian cycles */
417 cycles = (int)Perl_ceil((m / (Time64_T) days_in_gregorian_cycle) + 1);
419 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
420 year += (cycles * years_in_gregorian_cycle);
424 leap = IS_LEAP (year);
425 while (m < (Time64_T) -length_of_year[leap]) {
426 m += (Time64_T) length_of_year[leap];
428 leap = IS_LEAP (year);
433 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) {
434 m += (Time64_T) days_in_month[leap][v_tm_mon];
437 m += (Time64_T) days_in_month[leap][v_tm_mon];
441 if( p->tm_year != year ) {
448 /* At this point m is less than a year so casting to an int is safe */
449 p->tm_mday = (int) m + 1;
450 p->tm_yday = julian_days_by_month[leap][v_tm_mon] + (int)m;
451 p->tm_sec = v_tm_sec;
452 p->tm_min = v_tm_min;
453 p->tm_hour = v_tm_hour;
454 p->tm_mon = v_tm_mon;
455 p->tm_wday = v_tm_wday;
457 assert(S_check_tm(p));
463 struct TM *Perl_localtime64_r (const Time64_T *time, struct TM *local_tm)
471 assert(local_tm != NULL);
473 /* Use the system localtime() if time_t is small enough */
474 if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) {
475 safe_time = (time_t)*time;
477 TIME64_TRACE1("Using system localtime for %lld\n", *time);
479 LOCALTIME_R(&safe_time, &safe_date);
481 S_copy_little_tm_to_big_TM(&safe_date, local_tm);
482 assert(S_check_tm(local_tm));
487 if( Perl_gmtime64_r(time, &gm_tm) == NULL ) {
488 TIME64_TRACE1("gmtime64_r returned null for %lld\n", *time);
492 orig_year = gm_tm.tm_year;
494 if (gm_tm.tm_year > (2037 - 1900) ||
495 gm_tm.tm_year < (1970 - 1900)
498 TIME64_TRACE1("Mapping tm_year %lld to safe_year\n", (Year)gm_tm.tm_year);
499 gm_tm.tm_year = S_safe_year((Year)(gm_tm.tm_year + 1900)) - 1900;
502 safe_time = (time_t)S_timegm64(&gm_tm);
503 if( LOCALTIME_R(&safe_time, &safe_date) == NULL ) {
504 TIME64_TRACE1("localtime_r(%d) returned NULL\n", (int)safe_time);
508 S_copy_little_tm_to_big_TM(&safe_date, local_tm);
510 local_tm->tm_year = orig_year;
511 if( local_tm->tm_year != orig_year ) {
512 TIME64_TRACE2("tm_year overflow: tm_year %lld, orig_year %lld\n",
513 (Year)local_tm->tm_year, (Year)orig_year);
522 month_diff = local_tm->tm_mon - gm_tm.tm_mon;
524 /* When localtime is Dec 31st previous year and
525 gmtime is Jan 1st next year.
527 if( month_diff == 11 ) {
531 /* When localtime is Jan 1st, next year and
532 gmtime is Dec 31st, previous year.
534 if( month_diff == -11 ) {
538 /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st
539 in a non-leap xx00. There is one point in the cycle
540 we can't account for which the safe xx00 year is a leap
541 year. So we need to correct for Dec 31st coming out as
542 the 366th day of the year.
544 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 )
547 assert(S_check_tm(local_tm));