1 /*
2
3 Copyright (c) 2007-2008 Michael G Schwern
4
5 This software originally derived from Paul Sheer's pivotal_gmtime_r.c.
6
7 The MIT License:
8
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:
15
16 The above copyright notice and this permission notice shall be included in
17 all copies or substantial portions of the Software.
18
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
25 THE SOFTWARE.
26
27 */
28
29 /*
30
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.
35
36 Perl_localtime64_r() is a 64-bit equivalent of localtime_r().
37
38 Perl_gmtime64_r() is a 64-bit equivalent of gmtime_r().
39
40 */
41
42 #include "EXTERN.h"
43 #define PERL_IN_TIME64_C
44 #include "perl.h"
45 #include "time64.h"
46
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},
50 };
51
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},
55 };
56
57 static const short length_of_year[2] = { 365, 366 };
58
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;
62
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
73 };
74
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.
78 */
79 /* Number of days since epoch on Jan 1st, 2008 GMT */
80 #define CHEAT_DAYS (1199145600 / 24 / 60 / 60)
81 #define CHEAT_YEARS 108
82
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))
86
87 #ifdef USE_SYSTEM_LOCALTIME
88 # define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \
89 (a) <= SYSTEM_LOCALTIME_MAX && \
90 (a) >= SYSTEM_LOCALTIME_MIN \
91 )
92 #else
93 # define SHOULD_USE_SYSTEM_LOCALTIME(a) (0)
94 #endif
95
96 #ifdef USE_SYSTEM_GMTIME
97 # define SHOULD_USE_SYSTEM_GMTIME(a) ( \
98 (a) <= SYSTEM_GMTIME_MAX && \
99 (a) >= SYSTEM_GMTIME_MIN \
100 )
101 #else
102 # define SHOULD_USE_SYSTEM_GMTIME(a) (0)
103 #endif
104
105 /* Multi varadic macros are a C99 thing, alas */
106 #ifdef TIME_64_DEBUG
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))
111 #else
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)
116 #endif
117
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
134 # else
135 # define LOCALTIME_LOCK ENV_LOCALE_LOCK
136 # define LOCALTIME_UNLOCK ENV_LOCALE_UNLOCK
137 # endif
138 # ifdef PERL_REENTR_USING_GMTIME_R
139 # define GMTIME_LOCK ENV_LOCALE_READ_LOCK
140 # define GMTIME_UNLOCK ENV_LOCALE_READ_UNLOCK
141 # else
142 # define GMTIME_LOCK ENV_LOCALE_LOCK
143 # define GMTIME_UNLOCK ENV_LOCALE_UNLOCK
144 # endif
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
150 #endif
151
S_is_exception_century(Year year)152 static int S_is_exception_century(Year year)
153 {
154 const int is_exception = ((year % 100 == 0) && !(year % 400 == 0));
155 TIME64_TRACE1("# is_exception_century: %s\n", is_exception ? "yes" : "no");
156
157 return(is_exception);
158 }
159
160
S_timegm64(const struct TM * date)161 static Time64_T S_timegm64(const struct TM *date) {
162 int days = 0;
163 Time64_T seconds = 0;
164
165 if( date->tm_year > 70 ) {
166 Year year = 70;
167 while( year < date->tm_year ) {
168 days += length_of_year[IS_LEAP(year)];
169 year++;
170 }
171 }
172 else if ( date->tm_year < 70 ) {
173 Year year = 69;
174 do {
175 days -= length_of_year[IS_LEAP(year)];
176 year--;
177 } while( year >= date->tm_year );
178 }
179
180 days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon];
181 days += date->tm_mday - 1;
182
183 /* Avoid overflowing the days integer */
184 seconds = days;
185 seconds = seconds * 60 * 60 * 24;
186
187 seconds += date->tm_hour * 60 * 60;
188 seconds += date->tm_min * 60;
189 seconds += date->tm_sec;
190
191 return(seconds);
192 }
193
194
195 #ifdef DEBUGGING
S_check_tm(const struct TM * tm)196 static int S_check_tm(const struct TM *tm)
197 {
198 /* Don't forget leap seconds */
199 assert(tm->tm_sec >= 0);
200 assert(tm->tm_sec <= 61);
201
202 assert(tm->tm_min >= 0);
203 assert(tm->tm_min <= 59);
204
205 assert(tm->tm_hour >= 0);
206 assert(tm->tm_hour <= 23);
207
208 assert(tm->tm_mday >= 1);
209 assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]);
210
211 assert(tm->tm_mon >= 0);
212 assert(tm->tm_mon <= 11);
213
214 assert(tm->tm_wday >= 0);
215 assert(tm->tm_wday <= 6);
216
217 assert(tm->tm_yday >= 0);
218 assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]);
219
220 #ifdef HAS_TM_TM_GMTOFF
221 assert(tm->tm_gmtoff >= -24 * 60 * 60);
222 assert(tm->tm_gmtoff <= 24 * 60 * 60);
223 #endif
224
225 return 1;
226 }
227 #endif
228
229
230 /* The exceptional centuries without leap years cause the cycle to
231 shift by 16
232 */
S_cycle_offset(Year year)233 static Year S_cycle_offset(Year year)
234 {
235 const Year start_year = 2000;
236 Year year_diff = year - start_year;
237 Year exceptions;
238
239 if( year > start_year )
240 year_diff--;
241
242 exceptions = year_diff / 100;
243 exceptions -= year_diff / 400;
244
245 TIME64_TRACE3("# year: %lld, exceptions: %lld, year_diff: %lld\n",
246 year, exceptions, year_diff);
247
248 return exceptions * 16;
249 }
250
251 /* For a given year after 2038, pick the latest possible matching
252 year in the 28 year calendar cycle.
253
254 A matching year...
255 1) Starts on the same day of the week.
256 2) Has the same leap year status.
257
258 This is so the calendars match up.
259
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.
262
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
266 January 1st.
267 */
S_safe_year(Year year)268 static int S_safe_year(Year year)
269 {
270 int safe_year;
271 Year year_cycle = year + S_cycle_offset(year);
272
273 /* Change non-leap xx00 years to an equivalent */
274 if( S_is_exception_century(year) )
275 year_cycle += 11;
276
277 /* Also xx01 years, since the previous year will be wrong */
278 if( S_is_exception_century(year - 1) )
279 year_cycle += 17;
280
281 year_cycle %= SOLAR_CYCLE_LENGTH;
282 if( year_cycle < 0 )
283 year_cycle = SOLAR_CYCLE_LENGTH + year_cycle;
284
285 assert( year_cycle >= 0 );
286 assert( year_cycle < SOLAR_CYCLE_LENGTH );
287 safe_year = safe_years[year_cycle];
288
289 assert(safe_year <= 2037 && safe_year >= 2010);
290
291 TIME64_TRACE3("# year: %lld, year_cycle: %lld, safe_year: %d\n",
292 year, year_cycle, safe_year);
293
294 return safe_year;
295 }
296
297
S_copy_little_tm_to_big_TM(const struct tm * src,struct TM * dest)298 static void S_copy_little_tm_to_big_TM(const struct tm *src, struct TM *dest) {
299 assert(src);
300 assert(dest);
301 #ifdef USE_TM64
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;
311
312 # ifdef HAS_TM_TM_GMTOFF
313 dest->tm_gmtoff = src->tm_gmtoff;
314 # endif
315
316 # ifdef HAS_TM_TM_ZONE
317 dest->tm_zone = src->tm_zone;
318 # endif
319
320 #else
321 /* They're the same type */
322 memcpy(dest, src, sizeof(*dest));
323 #endif
324 }
325
Perl_gmtime64_r(const Time64_T * in_time,struct TM * p)326 struct TM *Perl_gmtime64_r (const Time64_T *in_time, struct TM *p)
327 {
328 int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday;
329 Time64_T v_tm_tday;
330 int leap;
331 Time64_T m;
332 Time64_T time = *in_time;
333 Year year = 70;
334 dTHX;
335
336 assert(p != NULL);
337
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;
341 struct tm safe_date;
342 struct tm * result;
343
344 GMTIME_LOCK;
345
346 /* reentr.h will automatically replace this with a call to gmtime_r()
347 * when appropriate */
348 result = gmtime(&safe_time);
349
350 assert(result != NULL);
351
352 #if defined(HAS_GMTIME_R) && defined(USE_REENTRANT_API)
353
354 PERL_UNUSED_VAR(safe_date);
355 #else
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));
361 result = &safe_date;
362 #endif
363 GMTIME_UNLOCK;
364
365 S_copy_little_tm_to_big_TM(result, p);
366 assert(S_check_tm(p));
367
368 return p;
369 }
370
371 #ifdef HAS_TM_TM_GMTOFF
372 p->tm_gmtoff = 0;
373 #endif
374 p->tm_isdst = 0;
375
376 #ifdef HAS_TM_TM_ZONE
377 p->tm_zone = "UTC";
378 #endif
379
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);
386 v_tm_tday = time;
387
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);
391
392 v_tm_wday = (int)Perl_fmod((v_tm_tday + 4.0), 7.0);
393 if (v_tm_wday < 0)
394 v_tm_wday += 7;
395 m = v_tm_tday;
396
397 if (m >= CHEAT_DAYS) {
398 year = CHEAT_YEARS;
399 m -= CHEAT_DAYS;
400 }
401
402 if (m >= 0) {
403 /* Gregorian cycles, this is huge optimization for distant times */
404 const int cycles = (int)Perl_floor(m / (Time64_T) days_in_gregorian_cycle);
405 if( cycles ) {
406 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
407 year += (cycles * years_in_gregorian_cycle);
408 }
409
410 /* Years */
411 leap = IS_LEAP (year);
412 while (m >= (Time64_T) length_of_year[leap]) {
413 m -= (Time64_T) length_of_year[leap];
414 year++;
415 leap = IS_LEAP (year);
416 }
417
418 /* Months */
419 v_tm_mon = 0;
420 while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) {
421 m -= (Time64_T) days_in_month[leap][v_tm_mon];
422 v_tm_mon++;
423 }
424 } else {
425 int cycles;
426
427 year--;
428
429 /* Gregorian cycles */
430 cycles = (int)Perl_ceil((m / (Time64_T) days_in_gregorian_cycle) + 1);
431 if( cycles ) {
432 m -= (cycles * (Time64_T) days_in_gregorian_cycle);
433 year += (cycles * years_in_gregorian_cycle);
434 }
435
436 /* Years */
437 leap = IS_LEAP (year);
438 while (m < (Time64_T) -length_of_year[leap]) {
439 m += (Time64_T) length_of_year[leap];
440 year--;
441 leap = IS_LEAP (year);
442 }
443
444 /* Months */
445 v_tm_mon = 11;
446 while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) {
447 m += (Time64_T) days_in_month[leap][v_tm_mon];
448 v_tm_mon--;
449 }
450 m += (Time64_T) days_in_month[leap][v_tm_mon];
451 }
452
453 p->tm_year = year;
454 if( p->tm_year != year ) {
455 #ifdef EOVERFLOW
456 errno = EOVERFLOW;
457 #endif
458 return NULL;
459 }
460
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;
469
470 assert(S_check_tm(p));
471
472 return p;
473 }
474
475
Perl_localtime64_r(const Time64_T * time,struct TM * local_tm)476 struct TM *Perl_localtime64_r (const Time64_T *time, struct TM *local_tm)
477 {
478 time_t safe_time;
479 struct tm safe_date;
480 const struct tm * result;
481 struct TM gm_tm;
482 Year orig_year = 0; /* initialise to avoid spurious compiler warning */
483 int month_diff;
484 const bool use_system = SHOULD_USE_SYSTEM_LOCALTIME(*time);
485 dTHX;
486
487 assert(local_tm != NULL);
488
489 /* Use the system localtime() if time_t is small enough */
490 if (use_system) {
491 safe_time = (time_t)*time;
492
493 TIME64_TRACE1("Using system localtime for %lld\n", *time);
494 }
495 else {
496 if (Perl_gmtime64_r(time, &gm_tm) == NULL) {
497 TIME64_TRACE1("gmtime64_r returned null for %lld\n", *time);
498 return NULL;
499 }
500
501 orig_year = gm_tm.tm_year;
502
503 if (gm_tm.tm_year > (2037 - 1900) ||
504 gm_tm.tm_year < (1970 - 1900)
505 )
506 {
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;
510 }
511
512 safe_time = (time_t)S_timegm64(&gm_tm);
513 }
514
515 LOCALTIME_LOCK;
516
517 /* reentr.h will automatically replace this with a call to localtime_r()
518 * when appropriate */
519 result = localtime(&safe_time);
520
521 if(UNLIKELY(result == NULL)) {
522 LOCALTIME_UNLOCK;
523 TIME64_TRACE1("localtime(%d) returned NULL\n", (int)safe_time);
524 return NULL;
525 }
526
527 #if ! defined(USE_REENTRANT_API) || defined(PERL_REENTR_USING_LOCALTIME_R)
528
529 PERL_UNUSED_VAR(safe_date);
530
531 #else
532
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
537 * result. */
538 memcpy(&safe_date, result, sizeof(safe_date));
539 result = &safe_date;
540
541 #endif
542
543 LOCALTIME_UNLOCK;
544
545 S_copy_little_tm_to_big_TM(result, local_tm);
546
547 if (! use_system) {
548
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);
553
554 #ifdef EOVERFLOW
555 errno = EOVERFLOW;
556 #endif
557 return NULL;
558 }
559
560 month_diff = local_tm->tm_mon - gm_tm.tm_mon;
561
562 /* When localtime is Dec 31st previous year and
563 gmtime is Jan 1st next year.
564 */
565 if( month_diff == 11 ) {
566 local_tm->tm_year--;
567 }
568
569 /* When localtime is Jan 1st, next year and
570 gmtime is Dec 31st, previous year.
571 */
572 if( month_diff == -11 ) {
573 local_tm->tm_year++;
574 }
575
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.
581 */
582 if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 )
583 local_tm->tm_yday--;
584
585 }
586
587 assert(S_check_tm(local_tm));
588
589 return local_tm;
590 }
591