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a272e669 |
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 | localtime64_r() is a 64-bit equivalent of localtime_r(). |
37 | |
38 | gmtime64_r() is a 64-bit equivalent of gmtime_r(). |
39 | |
40 | */ |
41 | |
af9b2bf5 |
42 | #include "localtime64.h" |
43 | |
a272e669 |
44 | static 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 | |
49 | static 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 | |
54 | static const int length_of_year[2] = { 365, 366 }; |
55 | |
56 | /* Number of days in a 400 year Gregorian cycle */ |
57 | static const int years_in_gregorian_cycle = 400; |
58 | static const int days_in_gregorian_cycle = (365 * 400) + 100 - 4 + 1; |
59 | |
60 | /* 28 year calendar cycle between 2010 and 2037 */ |
61 | static const int safe_years[28] = { |
62 | 2016, 2017, 2018, 2019, |
63 | 2020, 2021, 2022, 2023, |
64 | 2024, 2025, 2026, 2027, |
65 | 2028, 2029, 2030, 2031, |
66 | 2032, 2033, 2034, 2035, |
67 | 2036, 2037, 2010, 2011, |
68 | 2012, 2013, 2014, 2015 |
69 | }; |
70 | |
ea722b76 |
71 | #define SOLAR_CYCLE_LENGTH 28 |
72 | static const int dow_year_start[SOLAR_CYCLE_LENGTH] = { |
003c3b95 |
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 |
80 | }; |
81 | |
9af24521 |
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 |
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 | |
7bda3dfc |
93 | #define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \ |
94 | USE_SYSTEM_LOCALTIME && \ |
95 | (a) <= SYSTEM_LOCALTIME_MAX && \ |
96 | (a) >= SYSTEM_LOCALTIME_MIN \ |
97 | ) |
98 | #define SHOULD_USE_SYSTEM_GMTIME(a) ( \ |
99 | USE_SYSTEM_GMTIME && \ |
100 | (a) <= SYSTEM_GMTIME_MAX && \ |
101 | (a) >= SYSTEM_GMTIME_MIN \ |
102 | ) |
a64acb40 |
103 | |
104 | |
9af24521 |
105 | int _is_exception_century(Int64 year) |
a272e669 |
106 | { |
107 | int is_exception = ((year % 100 == 0) && !(year % 400 == 0)); |
108 | /* printf("is_exception_century: %s\n", is_exception ? "yes" : "no"); */ |
109 | |
110 | return(is_exception); |
111 | } |
112 | |
9af24521 |
113 | |
114 | /* timegm() is a GNU extension, so emulate it here if we need it */ |
115 | #ifdef HAS_TIMEGM |
116 | # define TIMEGM(n) timegm(n); |
117 | #else |
ea722b76 |
118 | # define TIMEGM(n) ((time_t)timegm64(n)); |
a272e669 |
119 | #endif |
120 | |
ea722b76 |
121 | Time64_T timegm64(struct tm *date) { |
122 | int days = 0; |
123 | Int64 seconds = 0; |
124 | Int64 year; |
a272e669 |
125 | |
9af24521 |
126 | if( date->tm_year > 70 ) { |
127 | year = 70; |
128 | while( year < date->tm_year ) { |
129 | days += length_of_year[IS_LEAP(year)]; |
130 | year++; |
a272e669 |
131 | } |
132 | } |
9af24521 |
133 | else if ( date->tm_year < 70 ) { |
134 | year = 69; |
135 | do { |
136 | days -= length_of_year[IS_LEAP(year)]; |
137 | year--; |
138 | } while( year >= date->tm_year ); |
139 | } |
140 | |
141 | days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon]; |
142 | days += date->tm_mday - 1; |
143 | |
ea722b76 |
144 | /* Avoid overflowing the days integer */ |
145 | seconds = days; |
146 | seconds = seconds * 60 * 60 * 24; |
147 | |
9af24521 |
148 | seconds += date->tm_hour * 60 * 60; |
149 | seconds += date->tm_min * 60; |
150 | seconds += date->tm_sec; |
151 | |
ea722b76 |
152 | return((Time64_T)seconds); |
9af24521 |
153 | } |
154 | |
155 | |
af9b2bf5 |
156 | int _check_tm(struct tm *tm) |
9af24521 |
157 | { |
9af24521 |
158 | /* Don't forget leap seconds */ |
af9b2bf5 |
159 | assert(tm->tm_sec >= 0); |
9af24521 |
160 | assert(tm->tm_sec <= 61); |
161 | |
af9b2bf5 |
162 | assert(tm->tm_min >= 0); |
9af24521 |
163 | assert(tm->tm_min <= 59); |
164 | |
165 | assert(tm->tm_hour >= 0); |
166 | assert(tm->tm_hour <= 23); |
167 | |
168 | assert(tm->tm_mday >= 1); |
af9b2bf5 |
169 | assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]); |
9af24521 |
170 | |
171 | assert(tm->tm_mon >= 0); |
172 | assert(tm->tm_mon <= 11); |
173 | |
174 | assert(tm->tm_wday >= 0); |
175 | assert(tm->tm_wday <= 6); |
176 | |
177 | assert(tm->tm_yday >= 0); |
af9b2bf5 |
178 | assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]); |
9af24521 |
179 | |
180 | #ifdef HAS_TM_TM_GMTOFF |
181 | assert(tm->tm_gmtoff >= -24 * 60 * 60); |
182 | assert(tm->tm_gmtoff <= 24 * 60 * 60); |
183 | #endif |
af9b2bf5 |
184 | |
185 | return 1; |
a272e669 |
186 | } |
a64acb40 |
187 | |
a272e669 |
188 | |
189 | /* The exceptional centuries without leap years cause the cycle to |
190 | shift by 16 |
191 | */ |
750c447b |
192 | Year _cycle_offset(Year year) |
a272e669 |
193 | { |
750c447b |
194 | const Year start_year = 2000; |
195 | Year year_diff = year - start_year; |
196 | Year exceptions; |
003c3b95 |
197 | |
198 | if( year > start_year ) |
199 | year_diff--; |
200 | |
750c447b |
201 | exceptions = year_diff / 100; |
202 | exceptions -= year_diff / 400; |
a272e669 |
203 | |
003c3b95 |
204 | /* |
205 | fprintf(stderr, "# year: %lld, exceptions: %lld, year_diff: %lld\n", |
206 | year, exceptions, year_diff); |
207 | */ |
a272e669 |
208 | |
209 | return exceptions * 16; |
210 | } |
211 | |
212 | /* For a given year after 2038, pick the latest possible matching |
213 | year in the 28 year calendar cycle. |
ea722b76 |
214 | |
215 | A matching year... |
216 | 1) Starts on the same day of the week. |
217 | 2) Has the same leap year status. |
218 | |
219 | This is so the calendars match up. |
220 | |
221 | Also the previous year must match. When doing Jan 1st you might |
222 | wind up on Dec 31st the previous year when doing a -UTC time zone. |
003c3b95 |
223 | |
224 | Finally, the next year must have the same start day of week. This |
225 | is for Dec 31st with a +UTC time zone. |
226 | It doesn't need the same leap year status since we only care about |
227 | January 1st. |
a272e669 |
228 | */ |
750c447b |
229 | int _safe_year(Year year) |
a272e669 |
230 | { |
231 | int safe_year; |
750c447b |
232 | Year year_cycle = year + _cycle_offset(year); |
a272e669 |
233 | |
234 | /* Change non-leap xx00 years to an equivalent */ |
235 | if( _is_exception_century(year) ) |
236 | year_cycle += 11; |
237 | |
003c3b95 |
238 | /* Also xx01 years, since the previous year will be wrong */ |
239 | if( _is_exception_century(year - 1) ) |
240 | year_cycle += 17; |
241 | |
a272e669 |
242 | year_cycle %= SOLAR_CYCLE_LENGTH; |
ea722b76 |
243 | if( year_cycle < 0 ) |
244 | year_cycle = SOLAR_CYCLE_LENGTH + year_cycle; |
a272e669 |
245 | |
003c3b95 |
246 | assert( year_cycle >= 0 ); |
247 | assert( year_cycle < SOLAR_CYCLE_LENGTH ); |
a272e669 |
248 | safe_year = safe_years[year_cycle]; |
249 | |
250 | assert(safe_year <= 2037 && safe_year >= 2010); |
251 | |
252 | /* |
253 | printf("year: %d, year_cycle: %d, safe_year: %d\n", |
254 | year, year_cycle, safe_year); |
255 | */ |
256 | |
257 | return safe_year; |
258 | } |
259 | |
750c447b |
260 | |
a272e669 |
261 | struct tm *gmtime64_r (const Time64_T *in_time, struct tm *p) |
262 | { |
263 | int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday; |
9af24521 |
264 | Int64 v_tm_tday; |
a272e669 |
265 | int leap; |
9af24521 |
266 | Int64 m; |
a272e669 |
267 | Time64_T time = *in_time; |
750c447b |
268 | Year year = 70; |
a272e669 |
269 | |
a64acb40 |
270 | /* Use the system gmtime() if time_t is small enough */ |
271 | if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) { |
272 | time_t safe_time = *in_time; |
750c447b |
273 | gmtime_r(&safe_time, p); |
af9b2bf5 |
274 | assert(_check_tm(p)); |
a64acb40 |
275 | return p; |
276 | } |
277 | |
9af24521 |
278 | #ifdef HAS_TM_TM_GMTOFF |
a272e669 |
279 | p->tm_gmtoff = 0; |
280 | #endif |
281 | p->tm_isdst = 0; |
282 | |
9af24521 |
283 | #ifdef HAS_TM_TM_ZONE |
a272e669 |
284 | p->tm_zone = "UTC"; |
285 | #endif |
286 | |
750c447b |
287 | v_tm_sec = (int)(time % 60); |
a272e669 |
288 | time /= 60; |
750c447b |
289 | v_tm_min = (int)(time % 60); |
a272e669 |
290 | time /= 60; |
750c447b |
291 | v_tm_hour = (int)(time % 24); |
a272e669 |
292 | time /= 24; |
293 | v_tm_tday = time; |
750c447b |
294 | |
a272e669 |
295 | WRAP (v_tm_sec, v_tm_min, 60); |
296 | WRAP (v_tm_min, v_tm_hour, 60); |
297 | WRAP (v_tm_hour, v_tm_tday, 24); |
750c447b |
298 | |
299 | v_tm_wday = (int)((v_tm_tday + 4) % 7); |
300 | if (v_tm_wday < 0) |
a272e669 |
301 | v_tm_wday += 7; |
302 | m = v_tm_tday; |
a272e669 |
303 | |
9af24521 |
304 | if (m >= CHEAT_DAYS) { |
305 | year = CHEAT_YEARS; |
306 | m -= CHEAT_DAYS; |
307 | } |
308 | |
309 | if (m >= 0) { |
a272e669 |
310 | /* Gregorian cycles, this is huge optimization for distant times */ |
311 | while (m >= (Time64_T) days_in_gregorian_cycle) { |
312 | m -= (Time64_T) days_in_gregorian_cycle; |
313 | year += years_in_gregorian_cycle; |
314 | } |
315 | |
316 | /* Years */ |
317 | leap = IS_LEAP (year); |
318 | while (m >= (Time64_T) length_of_year[leap]) { |
319 | m -= (Time64_T) length_of_year[leap]; |
320 | year++; |
321 | leap = IS_LEAP (year); |
322 | } |
323 | |
324 | /* Months */ |
325 | v_tm_mon = 0; |
326 | while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) { |
327 | m -= (Time64_T) days_in_month[leap][v_tm_mon]; |
328 | v_tm_mon++; |
329 | } |
330 | } else { |
9af24521 |
331 | year--; |
a272e669 |
332 | |
333 | /* Gregorian cycles */ |
334 | while (m < (Time64_T) -days_in_gregorian_cycle) { |
335 | m += (Time64_T) days_in_gregorian_cycle; |
336 | year -= years_in_gregorian_cycle; |
337 | } |
338 | |
339 | /* Years */ |
340 | leap = IS_LEAP (year); |
341 | while (m < (Time64_T) -length_of_year[leap]) { |
342 | m += (Time64_T) length_of_year[leap]; |
343 | year--; |
344 | leap = IS_LEAP (year); |
345 | } |
346 | |
347 | /* Months */ |
348 | v_tm_mon = 11; |
349 | while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) { |
350 | m += (Time64_T) days_in_month[leap][v_tm_mon]; |
351 | v_tm_mon--; |
352 | } |
353 | m += (Time64_T) days_in_month[leap][v_tm_mon]; |
354 | } |
355 | |
356 | p->tm_year = year; |
357 | if( p->tm_year != year ) { |
9af24521 |
358 | #ifdef EOVERFLOW |
a272e669 |
359 | errno = EOVERFLOW; |
9af24521 |
360 | #endif |
a272e669 |
361 | return NULL; |
362 | } |
363 | |
364 | p->tm_mday = (int) m + 1; |
750c447b |
365 | p->tm_yday = (int) julian_days_by_month[leap][v_tm_mon] + m; |
a272e669 |
366 | p->tm_sec = v_tm_sec, p->tm_min = v_tm_min, p->tm_hour = v_tm_hour, |
367 | p->tm_mon = v_tm_mon, p->tm_wday = v_tm_wday; |
368 | |
af9b2bf5 |
369 | assert(_check_tm(p)); |
a272e669 |
370 | |
371 | return p; |
372 | } |
373 | |
374 | |
375 | struct tm *localtime64_r (const Time64_T *time, struct tm *local_tm) |
376 | { |
377 | time_t safe_time; |
378 | struct tm gm_tm; |
750c447b |
379 | Year orig_year; |
a272e669 |
380 | int month_diff; |
381 | |
a64acb40 |
382 | /* Use the system localtime() if time_t is small enough */ |
383 | if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) { |
384 | safe_time = *time; |
385 | localtime_r(&safe_time, local_tm); |
af9b2bf5 |
386 | assert(_check_tm(local_tm)); |
a64acb40 |
387 | return local_tm; |
388 | } |
389 | |
af832814 |
390 | if( gmtime64_r(time, &gm_tm) == NULL ) |
391 | return NULL; |
392 | |
a272e669 |
393 | orig_year = gm_tm.tm_year; |
394 | |
c07fe26c |
395 | if (gm_tm.tm_year > (2037 - 1900) || |
396 | gm_tm.tm_year < (1902 - 1900) |
397 | ) |
398 | { |
a272e669 |
399 | gm_tm.tm_year = _safe_year(gm_tm.tm_year + 1900) - 1900; |
c07fe26c |
400 | } |
a272e669 |
401 | |
9af24521 |
402 | safe_time = TIMEGM(&gm_tm); |
af832814 |
403 | if( localtime_r(&safe_time, local_tm) == NULL ) |
404 | return NULL; |
a272e669 |
405 | |
406 | local_tm->tm_year = orig_year; |
af832814 |
407 | if( local_tm->tm_year != orig_year ) { |
408 | #ifdef EOVERFLOW |
409 | errno = EOVERFLOW; |
410 | #endif |
411 | return NULL; |
412 | } |
413 | |
414 | |
a272e669 |
415 | month_diff = local_tm->tm_mon - gm_tm.tm_mon; |
416 | |
417 | /* When localtime is Dec 31st previous year and |
418 | gmtime is Jan 1st next year. |
419 | */ |
420 | if( month_diff == 11 ) { |
421 | local_tm->tm_year--; |
422 | } |
423 | |
424 | /* When localtime is Jan 1st, next year and |
425 | gmtime is Dec 31st, previous year. |
426 | */ |
427 | if( month_diff == -11 ) { |
428 | local_tm->tm_year++; |
429 | } |
430 | |
431 | /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st |
432 | in a non-leap xx00. There is one point in the cycle |
433 | we can't account for which the safe xx00 year is a leap |
434 | year. So we need to correct for Dec 31st comming out as |
435 | the 366th day of the year. |
436 | */ |
437 | if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 ) |
438 | local_tm->tm_yday--; |
439 | |
af9b2bf5 |
440 | assert(_check_tm(local_tm)); |
a272e669 |
441 | |
442 | return local_tm; |
443 | } |