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a272e669
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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
36localtime64_r() is a 64-bit equivalent of localtime_r().
37
38gmtime64_r() is a 64-bit equivalent of gmtime_r().
39
40*/
41
7643e68f 42#include "time64.h"
af9b2bf5 43
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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;
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58static const int days_in_gregorian_cycle = (365 * 400) + 100 - 4 + 1;
59
60/* 28 year calendar cycle between 2010 and 2037 */
806a119a
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61#define SOLAR_CYCLE_LENGTH 28
62static const int safe_years[SOLAR_CYCLE_LENGTH] = {
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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
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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 */
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80};
81
9af24521
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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
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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
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93#ifdef USE_SYSTEM_LOCALTIME
94# define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \
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95 (a) <= SYSTEM_LOCALTIME_MAX && \
96 (a) >= SYSTEM_LOCALTIME_MIN \
97)
b86b480f
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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) ( \
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104 (a) <= SYSTEM_GMTIME_MAX && \
105 (a) >= SYSTEM_GMTIME_MIN \
106)
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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
d4fb0a1f
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113# define TRACE(format) (fprintf(stderr, format))
114# define TRACE1(format, var1) (fprintf(stderr, format, var1))
115# define TRACE2(format, var1, var2) (fprintf(stderr, format, var1, var2))
116# define TRACE3(format, var1, var2, var3) (fprintf(stderr, format, var1, var2, var3))
461d5a49 117#else
d4fb0a1f
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118# define TRACE(format) ((void)0)
119# define TRACE1(format, var1) ((void)0)
120# define TRACE2(format, var1, var2) ((void)0)
121# define TRACE3(format, var1, var2, var3) ((void)0)
461d5a49 122#endif
a64acb40 123
b86b480f 124static int is_exception_century(Year year)
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125{
126 int is_exception = ((year % 100 == 0) && !(year % 400 == 0));
d4fb0a1f 127 TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no");
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128
129 return(is_exception);
130}
131
9af24521 132
806a119a 133Time64_T timegm64(struct TM *date) {
b86b480f
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134 int days = 0;
135 Time64_T seconds = 0;
136 Year year;
a272e669 137
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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++;
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143 }
144 }
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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
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156 /* Avoid overflowing the days integer */
157 seconds = days;
158 seconds = seconds * 60 * 60 * 24;
159
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160 seconds += date->tm_hour * 60 * 60;
161 seconds += date->tm_min * 60;
162 seconds += date->tm_sec;
163
b86b480f 164 return(seconds);
9af24521
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165}
166
167
554fcfb9 168#ifdef DEBUGGING
806a119a 169static int check_tm(struct TM *tm)
9af24521 170{
9af24521 171 /* Don't forget leap seconds */
af9b2bf5 172 assert(tm->tm_sec >= 0);
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173 assert(tm->tm_sec <= 61);
174
af9b2bf5 175 assert(tm->tm_min >= 0);
9af24521
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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]);
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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)]);
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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
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197
198 return 1;
a272e669 199}
554fcfb9 200#endif
a64acb40 201
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202
203/* The exceptional centuries without leap years cause the cycle to
204 shift by 16
205*/
806a119a 206static Year cycle_offset(Year year)
a272e669 207{
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208 const Year start_year = 2000;
209 Year year_diff = year - start_year;
210 Year exceptions;
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211
212 if( year > start_year )
213 year_diff--;
214
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215 exceptions = year_diff / 100;
216 exceptions -= year_diff / 400;
a272e669 217
d4fb0a1f 218 TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n",
461d5a49 219 year, exceptions, year_diff);
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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.
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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
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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*/
806a119a 241static int safe_year(Year year)
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242{
243 int safe_year;
806a119a 244 Year year_cycle = year + cycle_offset(year);
a272e669
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245
246 /* Change non-leap xx00 years to an equivalent */
806a119a 247 if( is_exception_century(year) )
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248 year_cycle += 11;
249
003c3b95 250 /* Also xx01 years, since the previous year will be wrong */
806a119a 251 if( is_exception_century(year - 1) )
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252 year_cycle += 17;
253
a272e669 254 year_cycle %= SOLAR_CYCLE_LENGTH;
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255 if( year_cycle < 0 )
256 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle;
a272e669 257
003c3b95
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258 assert( year_cycle >= 0 );
259 assert( year_cycle < SOLAR_CYCLE_LENGTH );
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260 safe_year = safe_years[year_cycle];
261
262 assert(safe_year <= 2037 && safe_year >= 2010);
263
d4fb0a1f 264 TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n",
461d5a49 265 year, year_cycle, safe_year);
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266
267 return safe_year;
268}
269
750c447b 270
ef3a38ff 271void 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;
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
ef3a38ff 303void copy_big_TM_to_little_tm(const struct TM *src, struct tm *dest) {
806a119a
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304 if( src == NULL ) {
305 memset(dest, 0, sizeof(*dest));
306 }
307 else {
308# ifdef USE_TM64
309 dest->tm_sec = src->tm_sec;
310 dest->tm_min = src->tm_min;
311 dest->tm_hour = src->tm_hour;
312 dest->tm_mday = src->tm_mday;
313 dest->tm_mon = src->tm_mon;
314 dest->tm_year = (int)src->tm_year;
315 dest->tm_wday = src->tm_wday;
316 dest->tm_yday = src->tm_yday;
317 dest->tm_isdst = src->tm_isdst;
318
319# ifdef HAS_TM_TM_GMTOFF
320 dest->tm_gmtoff = src->tm_gmtoff;
321# endif
322
323# ifdef HAS_TM_TM_ZONE
324 dest->tm_zone = src->tm_zone;
325# endif
326
327# else
328 /* They're the same type */
329 memcpy(dest, src, sizeof(*dest));
330# endif
331 }
332}
333
334
948ea7a9
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335/* Simulate localtime_r() to the best of our ability */
336struct tm * fake_localtime_r(const time_t *clock, struct tm *result) {
478780ab 337 dTHX; /* in case the following is defined as Perl_my_localtime(aTHX_ ...) */
948ea7a9
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338 const struct tm *static_result = localtime(clock);
339
340 assert(result != NULL);
341
342 if( static_result == NULL ) {
343 memset(result, 0, sizeof(*result));
344 return NULL;
345 }
346 else {
347 memcpy(result, static_result, sizeof(*result));
348 return result;
349 }
350}
351
352
353/* Simulate gmtime_r() to the best of our ability */
354struct tm * fake_gmtime_r(const time_t *clock, struct tm *result) {
478780ab 355 dTHX; /* in case the following is defined as Perl_my_gmtime(aTHX_ ...) */
948ea7a9
MS
356 const struct tm *static_result = gmtime(clock);
357
358 assert(result != NULL);
359
360 if( static_result == NULL ) {
361 memset(result, 0, sizeof(*result));
362 return NULL;
363 }
364 else {
365 memcpy(result, static_result, sizeof(*result));
366 return result;
367 }
368}
369
370
806a119a 371struct TM *gmtime64_r (const Time64_T *in_time, struct TM *p)
a272e669
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372{
373 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday;
b86b480f 374 Time64_T v_tm_tday;
a272e669 375 int leap;
b86b480f 376 Time64_T m;
a272e669 377 Time64_T time = *in_time;
750c447b 378 Year year = 70;
806a119a 379 int cycles = 0;
a272e669 380
948ea7a9
MS
381 assert(p != NULL);
382
a64acb40
MS
383 /* Use the system gmtime() if time_t is small enough */
384 if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) {
cd1759d8 385 time_t safe_time = (time_t)*in_time;
806a119a
MS
386 struct tm safe_date;
387 GMTIME_R(&safe_time, &safe_date);
388
ef3a38ff 389 copy_little_tm_to_big_TM(&safe_date, p);
806a119a
MS
390 assert(check_tm(p));
391
a64acb40
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392 return p;
393 }
394
9af24521 395#ifdef HAS_TM_TM_GMTOFF
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396 p->tm_gmtoff = 0;
397#endif
398 p->tm_isdst = 0;
399
9af24521 400#ifdef HAS_TM_TM_ZONE
a272e669
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401 p->tm_zone = "UTC";
402#endif
403
750c447b 404 v_tm_sec = (int)(time % 60);
a272e669 405 time /= 60;
750c447b 406 v_tm_min = (int)(time % 60);
a272e669 407 time /= 60;
750c447b 408 v_tm_hour = (int)(time % 24);
a272e669
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409 time /= 24;
410 v_tm_tday = time;
750c447b 411
a272e669
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412 WRAP (v_tm_sec, v_tm_min, 60);
413 WRAP (v_tm_min, v_tm_hour, 60);
414 WRAP (v_tm_hour, v_tm_tday, 24);
750c447b
MS
415
416 v_tm_wday = (int)((v_tm_tday + 4) % 7);
417 if (v_tm_wday < 0)
a272e669
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418 v_tm_wday += 7;
419 m = v_tm_tday;
a272e669 420
9af24521
MS
421 if (m >= CHEAT_DAYS) {
422 year = CHEAT_YEARS;
423 m -= CHEAT_DAYS;
424 }
425
426 if (m >= 0) {
a272e669 427 /* Gregorian cycles, this is huge optimization for distant times */
461d5a49 428 cycles = (int)(m / (Time64_T) days_in_gregorian_cycle);
806a119a
MS
429 if( cycles ) {
430 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
431 year += (cycles * years_in_gregorian_cycle);
a272e669
MS
432 }
433
434 /* Years */
435 leap = IS_LEAP (year);
436 while (m >= (Time64_T) length_of_year[leap]) {
437 m -= (Time64_T) length_of_year[leap];
438 year++;
439 leap = IS_LEAP (year);
440 }
441
442 /* Months */
443 v_tm_mon = 0;
444 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) {
445 m -= (Time64_T) days_in_month[leap][v_tm_mon];
446 v_tm_mon++;
447 }
448 } else {
9af24521 449 year--;
a272e669
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450
451 /* Gregorian cycles */
461d5a49 452 cycles = (int)((m / (Time64_T) days_in_gregorian_cycle) + 1);
806a119a
MS
453 if( cycles ) {
454 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
455 year += (cycles * years_in_gregorian_cycle);
a272e669
MS
456 }
457
458 /* Years */
459 leap = IS_LEAP (year);
460 while (m < (Time64_T) -length_of_year[leap]) {
461 m += (Time64_T) length_of_year[leap];
462 year--;
463 leap = IS_LEAP (year);
464 }
465
466 /* Months */
467 v_tm_mon = 11;
468 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) {
469 m += (Time64_T) days_in_month[leap][v_tm_mon];
470 v_tm_mon--;
471 }
472 m += (Time64_T) days_in_month[leap][v_tm_mon];
473 }
474
475 p->tm_year = year;
476 if( p->tm_year != year ) {
9af24521 477#ifdef EOVERFLOW
a272e669 478 errno = EOVERFLOW;
9af24521 479#endif
a272e669
MS
480 return NULL;
481 }
482
b86b480f 483 /* At this point m is less than a year so casting to an int is safe */
a272e669 484 p->tm_mday = (int) m + 1;
b86b480f
MS
485 p->tm_yday = julian_days_by_month[leap][v_tm_mon] + (int)m;
486 p->tm_sec = v_tm_sec;
487 p->tm_min = v_tm_min;
488 p->tm_hour = v_tm_hour;
489 p->tm_mon = v_tm_mon;
490 p->tm_wday = v_tm_wday;
a272e669 491
806a119a 492 assert(check_tm(p));
a272e669
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493
494 return p;
495}
496
497
806a119a 498struct TM *localtime64_r (const Time64_T *time, struct TM *local_tm)
a272e669
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499{
500 time_t safe_time;
806a119a
MS
501 struct tm safe_date;
502 struct TM gm_tm;
750c447b 503 Year orig_year;
a272e669
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504 int month_diff;
505
948ea7a9
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506 assert(local_tm != NULL);
507
a64acb40
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508 /* Use the system localtime() if time_t is small enough */
509 if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) {
cd1759d8 510 safe_time = (time_t)*time;
806a119a 511
d4fb0a1f 512 TRACE1("Using system localtime for %lld\n", *time);
461d5a49 513
806a119a
MS
514 LOCALTIME_R(&safe_time, &safe_date);
515
ef3a38ff 516 copy_little_tm_to_big_TM(&safe_date, local_tm);
806a119a
MS
517 assert(check_tm(local_tm));
518
a64acb40
MS
519 return local_tm;
520 }
521
461d5a49 522 if( gmtime64_r(time, &gm_tm) == NULL ) {
d4fb0a1f 523 TRACE1("gmtime64_r returned null for %lld\n", *time);
af832814 524 return NULL;
461d5a49 525 }
af832814 526
a272e669
MS
527 orig_year = gm_tm.tm_year;
528
c07fe26c 529 if (gm_tm.tm_year > (2037 - 1900) ||
461d5a49 530 gm_tm.tm_year < (1970 - 1900)
c07fe26c
MS
531 )
532 {
d4fb0a1f 533 TRACE1("Mapping tm_year %lld to safe_year\n", (Year)gm_tm.tm_year);
b86b480f 534 gm_tm.tm_year = safe_year((Year)(gm_tm.tm_year + 1900)) - 1900;
c07fe26c 535 }
a272e669 536
cd1759d8 537 safe_time = (time_t)timegm64(&gm_tm);
461d5a49 538 if( LOCALTIME_R(&safe_time, &safe_date) == NULL ) {
d4fb0a1f 539 TRACE1("localtime_r(%d) returned NULL\n", (int)safe_time);
af832814 540 return NULL;
461d5a49 541 }
a272e669 542
ef3a38ff 543 copy_little_tm_to_big_TM(&safe_date, local_tm);
806a119a 544
a272e669 545 local_tm->tm_year = orig_year;
af832814 546 if( local_tm->tm_year != orig_year ) {
d4fb0a1f 547 TRACE2("tm_year overflow: tm_year %lld, orig_year %lld\n",
461d5a49
MS
548 (Year)local_tm->tm_year, (Year)orig_year);
549
af832814
MS
550#ifdef EOVERFLOW
551 errno = EOVERFLOW;
552#endif
553 return NULL;
554 }
555
556
a272e669
MS
557 month_diff = local_tm->tm_mon - gm_tm.tm_mon;
558
559 /* When localtime is Dec 31st previous year and
560 gmtime is Jan 1st next year.
561 */
562 if( month_diff == 11 ) {
563 local_tm->tm_year--;
564 }
565
566 /* When localtime is Jan 1st, next year and
567 gmtime is Dec 31st, previous year.
568 */
569 if( month_diff == -11 ) {
570 local_tm->tm_year++;
571 }
572
573 /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st
574 in a non-leap xx00. There is one point in the cycle
575 we can't account for which the safe xx00 year is a leap
576 year. So we need to correct for Dec 31st comming out as
577 the 366th day of the year.
578 */
579 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 )
580 local_tm->tm_yday--;
581
806a119a 582 assert(check_tm(local_tm));
a272e669
MS
583
584 return local_tm;
585}