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a272e669 MS |
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 MS |
42 | #include "localtime64.h" |
43 | ||
a272e669 MS |
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 | ||
71 | static const int dow_year_start[28] = { | |
72 | 5, 0, 1, 2, /* 2016 - 2019 */ | |
73 | 3, 5, 6, 0, | |
74 | 1, 3, 4, 5, | |
75 | 6, 1, 2, 3, | |
76 | 4, 6, 0, 1, | |
77 | 2, 4, 5, 6, /* 2036, 2037, 2010, 2011 */ | |
78 | 0, 2, 3, 4 /* 2012, 2013, 2014, 2015 */ | |
79 | }; | |
80 | ||
9af24521 MS |
81 | /* Let's assume people are going to be looking for dates in the future. |
82 | Let's provide some cheats so you can skip ahead. | |
83 | This has a 4x speed boost when near 2008. | |
84 | */ | |
85 | /* Number of days since epoch on Jan 1st, 2008 GMT */ | |
86 | #define CHEAT_DAYS (1199145600 / 24 / 60 / 60) | |
87 | #define CHEAT_YEARS 108 | |
a272e669 MS |
88 | |
89 | #define IS_LEAP(n) ((!(((n) + 1900) % 400) || (!(((n) + 1900) % 4) && (((n) + 1900) % 100))) != 0) | |
90 | #define WRAP(a,b,m) ((a) = ((a) < 0 ) ? ((b)--, (a) + (m)) : (a)) | |
91 | ||
7bda3dfc MS |
92 | #define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \ |
93 | USE_SYSTEM_LOCALTIME && \ | |
94 | (a) <= SYSTEM_LOCALTIME_MAX && \ | |
95 | (a) >= SYSTEM_LOCALTIME_MIN \ | |
96 | ) | |
97 | #define SHOULD_USE_SYSTEM_GMTIME(a) ( \ | |
98 | USE_SYSTEM_GMTIME && \ | |
99 | (a) <= SYSTEM_GMTIME_MAX && \ | |
100 | (a) >= SYSTEM_GMTIME_MIN \ | |
101 | ) | |
a64acb40 MS |
102 | |
103 | ||
9af24521 | 104 | int _is_exception_century(Int64 year) |
a272e669 MS |
105 | { |
106 | int is_exception = ((year % 100 == 0) && !(year % 400 == 0)); | |
107 | /* printf("is_exception_century: %s\n", is_exception ? "yes" : "no"); */ | |
108 | ||
109 | return(is_exception); | |
110 | } | |
111 | ||
9af24521 MS |
112 | |
113 | /* timegm() is a GNU extension, so emulate it here if we need it */ | |
114 | #ifdef HAS_TIMEGM | |
115 | # define TIMEGM(n) timegm(n); | |
116 | #else | |
117 | # define TIMEGM(n) _my_timegm(n); | |
a272e669 MS |
118 | #endif |
119 | ||
9af24521 MS |
120 | time_t _my_timegm(struct tm *date) { |
121 | int days = 0; | |
122 | int seconds = 0; | |
123 | time_t time; | |
124 | int year; | |
a272e669 | 125 | |
9af24521 MS |
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 MS |
131 | } |
132 | } | |
9af24521 MS |
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 | ||
144 | seconds += date->tm_hour * 60 * 60; | |
145 | seconds += date->tm_min * 60; | |
146 | seconds += date->tm_sec; | |
147 | ||
148 | time = (time_t)(days * 60 * 60 * 24) + seconds; | |
149 | ||
150 | return(time); | |
151 | } | |
152 | ||
153 | ||
af9b2bf5 | 154 | int _check_tm(struct tm *tm) |
9af24521 | 155 | { |
9af24521 | 156 | /* Don't forget leap seconds */ |
af9b2bf5 | 157 | assert(tm->tm_sec >= 0); |
9af24521 MS |
158 | assert(tm->tm_sec <= 61); |
159 | ||
af9b2bf5 | 160 | assert(tm->tm_min >= 0); |
9af24521 MS |
161 | assert(tm->tm_min <= 59); |
162 | ||
163 | assert(tm->tm_hour >= 0); | |
164 | assert(tm->tm_hour <= 23); | |
165 | ||
166 | assert(tm->tm_mday >= 1); | |
af9b2bf5 | 167 | assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]); |
9af24521 MS |
168 | |
169 | assert(tm->tm_mon >= 0); | |
170 | assert(tm->tm_mon <= 11); | |
171 | ||
172 | assert(tm->tm_wday >= 0); | |
173 | assert(tm->tm_wday <= 6); | |
174 | ||
175 | assert(tm->tm_yday >= 0); | |
af9b2bf5 | 176 | assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]); |
9af24521 MS |
177 | |
178 | #ifdef HAS_TM_TM_GMTOFF | |
179 | assert(tm->tm_gmtoff >= -24 * 60 * 60); | |
180 | assert(tm->tm_gmtoff <= 24 * 60 * 60); | |
181 | #endif | |
af9b2bf5 MS |
182 | |
183 | return 1; | |
a272e669 | 184 | } |
a64acb40 | 185 | |
a272e669 MS |
186 | |
187 | /* The exceptional centuries without leap years cause the cycle to | |
188 | shift by 16 | |
189 | */ | |
9af24521 | 190 | int _cycle_offset(Int64 year) |
a272e669 | 191 | { |
9af24521 MS |
192 | const Int64 start_year = 2000; |
193 | Int64 year_diff = year - start_year - 1; | |
194 | Int64 exceptions = year_diff / 100; | |
a272e669 MS |
195 | exceptions -= year_diff / 400; |
196 | ||
a272e669 MS |
197 | /* printf("year: %d, exceptions: %d\n", year, exceptions); */ |
198 | ||
199 | return exceptions * 16; | |
200 | } | |
201 | ||
202 | /* For a given year after 2038, pick the latest possible matching | |
203 | year in the 28 year calendar cycle. | |
204 | */ | |
205 | #define SOLAR_CYCLE_LENGTH 28 | |
9af24521 | 206 | int _safe_year(Int64 year) |
a272e669 MS |
207 | { |
208 | int safe_year; | |
9af24521 | 209 | Int64 year_cycle = year + _cycle_offset(year); |
a272e669 MS |
210 | |
211 | /* Change non-leap xx00 years to an equivalent */ | |
212 | if( _is_exception_century(year) ) | |
213 | year_cycle += 11; | |
214 | ||
215 | year_cycle %= SOLAR_CYCLE_LENGTH; | |
216 | ||
217 | safe_year = safe_years[year_cycle]; | |
218 | ||
219 | assert(safe_year <= 2037 && safe_year >= 2010); | |
220 | ||
221 | /* | |
222 | printf("year: %d, year_cycle: %d, safe_year: %d\n", | |
223 | year, year_cycle, safe_year); | |
224 | */ | |
225 | ||
226 | return safe_year; | |
227 | } | |
228 | ||
229 | struct tm *gmtime64_r (const Time64_T *in_time, struct tm *p) | |
230 | { | |
231 | int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday; | |
9af24521 | 232 | Int64 v_tm_tday; |
a272e669 | 233 | int leap; |
9af24521 | 234 | Int64 m; |
a272e669 | 235 | Time64_T time = *in_time; |
9af24521 | 236 | Int64 year = 70; |
a272e669 | 237 | |
a64acb40 MS |
238 | /* Use the system gmtime() if time_t is small enough */ |
239 | if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) { | |
240 | time_t safe_time = *in_time; | |
241 | localtime_r(&safe_time, p); | |
af9b2bf5 | 242 | assert(_check_tm(p)); |
a64acb40 MS |
243 | return p; |
244 | } | |
245 | ||
9af24521 | 246 | #ifdef HAS_TM_TM_GMTOFF |
a272e669 MS |
247 | p->tm_gmtoff = 0; |
248 | #endif | |
249 | p->tm_isdst = 0; | |
250 | ||
9af24521 | 251 | #ifdef HAS_TM_TM_ZONE |
a272e669 MS |
252 | p->tm_zone = "UTC"; |
253 | #endif | |
254 | ||
255 | v_tm_sec = time % 60; | |
256 | time /= 60; | |
257 | v_tm_min = time % 60; | |
258 | time /= 60; | |
259 | v_tm_hour = time % 24; | |
260 | time /= 24; | |
261 | v_tm_tday = time; | |
262 | WRAP (v_tm_sec, v_tm_min, 60); | |
263 | WRAP (v_tm_min, v_tm_hour, 60); | |
264 | WRAP (v_tm_hour, v_tm_tday, 24); | |
265 | if ((v_tm_wday = (v_tm_tday + 4) % 7) < 0) | |
266 | v_tm_wday += 7; | |
267 | m = v_tm_tday; | |
a272e669 | 268 | |
9af24521 MS |
269 | if (m >= CHEAT_DAYS) { |
270 | year = CHEAT_YEARS; | |
271 | m -= CHEAT_DAYS; | |
272 | } | |
273 | ||
274 | if (m >= 0) { | |
a272e669 MS |
275 | /* Gregorian cycles, this is huge optimization for distant times */ |
276 | while (m >= (Time64_T) days_in_gregorian_cycle) { | |
277 | m -= (Time64_T) days_in_gregorian_cycle; | |
278 | year += years_in_gregorian_cycle; | |
279 | } | |
280 | ||
281 | /* Years */ | |
282 | leap = IS_LEAP (year); | |
283 | while (m >= (Time64_T) length_of_year[leap]) { | |
284 | m -= (Time64_T) length_of_year[leap]; | |
285 | year++; | |
286 | leap = IS_LEAP (year); | |
287 | } | |
288 | ||
289 | /* Months */ | |
290 | v_tm_mon = 0; | |
291 | while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) { | |
292 | m -= (Time64_T) days_in_month[leap][v_tm_mon]; | |
293 | v_tm_mon++; | |
294 | } | |
295 | } else { | |
9af24521 | 296 | year--; |
a272e669 MS |
297 | |
298 | /* Gregorian cycles */ | |
299 | while (m < (Time64_T) -days_in_gregorian_cycle) { | |
300 | m += (Time64_T) days_in_gregorian_cycle; | |
301 | year -= years_in_gregorian_cycle; | |
302 | } | |
303 | ||
304 | /* Years */ | |
305 | leap = IS_LEAP (year); | |
306 | while (m < (Time64_T) -length_of_year[leap]) { | |
307 | m += (Time64_T) length_of_year[leap]; | |
308 | year--; | |
309 | leap = IS_LEAP (year); | |
310 | } | |
311 | ||
312 | /* Months */ | |
313 | v_tm_mon = 11; | |
314 | while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) { | |
315 | m += (Time64_T) days_in_month[leap][v_tm_mon]; | |
316 | v_tm_mon--; | |
317 | } | |
318 | m += (Time64_T) days_in_month[leap][v_tm_mon]; | |
319 | } | |
320 | ||
321 | p->tm_year = year; | |
322 | if( p->tm_year != year ) { | |
9af24521 | 323 | #ifdef EOVERFLOW |
a272e669 | 324 | errno = EOVERFLOW; |
9af24521 | 325 | #endif |
a272e669 MS |
326 | return NULL; |
327 | } | |
328 | ||
329 | p->tm_mday = (int) m + 1; | |
330 | p->tm_yday = julian_days_by_month[leap][v_tm_mon] + m; | |
331 | p->tm_sec = v_tm_sec, p->tm_min = v_tm_min, p->tm_hour = v_tm_hour, | |
332 | p->tm_mon = v_tm_mon, p->tm_wday = v_tm_wday; | |
333 | ||
af9b2bf5 | 334 | assert(_check_tm(p)); |
a272e669 MS |
335 | |
336 | return p; | |
337 | } | |
338 | ||
339 | ||
340 | struct tm *localtime64_r (const Time64_T *time, struct tm *local_tm) | |
341 | { | |
342 | time_t safe_time; | |
343 | struct tm gm_tm; | |
9af24521 | 344 | Int64 orig_year; |
a272e669 MS |
345 | int month_diff; |
346 | ||
a64acb40 MS |
347 | /* Use the system localtime() if time_t is small enough */ |
348 | if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) { | |
349 | safe_time = *time; | |
350 | localtime_r(&safe_time, local_tm); | |
af9b2bf5 | 351 | assert(_check_tm(local_tm)); |
a64acb40 MS |
352 | return local_tm; |
353 | } | |
354 | ||
af832814 MS |
355 | if( gmtime64_r(time, &gm_tm) == NULL ) |
356 | return NULL; | |
357 | ||
a272e669 MS |
358 | orig_year = gm_tm.tm_year; |
359 | ||
c07fe26c MS |
360 | if (gm_tm.tm_year > (2037 - 1900) || |
361 | gm_tm.tm_year < (1902 - 1900) | |
362 | ) | |
363 | { | |
a272e669 | 364 | gm_tm.tm_year = _safe_year(gm_tm.tm_year + 1900) - 1900; |
c07fe26c | 365 | } |
a272e669 | 366 | |
9af24521 | 367 | safe_time = TIMEGM(&gm_tm); |
af832814 MS |
368 | if( localtime_r(&safe_time, local_tm) == NULL ) |
369 | return NULL; | |
a272e669 MS |
370 | |
371 | local_tm->tm_year = orig_year; | |
af832814 MS |
372 | if( local_tm->tm_year != orig_year ) { |
373 | #ifdef EOVERFLOW | |
374 | errno = EOVERFLOW; | |
375 | #endif | |
376 | return NULL; | |
377 | } | |
378 | ||
379 | ||
a272e669 MS |
380 | month_diff = local_tm->tm_mon - gm_tm.tm_mon; |
381 | ||
382 | /* When localtime is Dec 31st previous year and | |
383 | gmtime is Jan 1st next year. | |
384 | */ | |
385 | if( month_diff == 11 ) { | |
386 | local_tm->tm_year--; | |
387 | } | |
388 | ||
389 | /* When localtime is Jan 1st, next year and | |
390 | gmtime is Dec 31st, previous year. | |
391 | */ | |
392 | if( month_diff == -11 ) { | |
393 | local_tm->tm_year++; | |
394 | } | |
395 | ||
396 | /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st | |
397 | in a non-leap xx00. There is one point in the cycle | |
398 | we can't account for which the safe xx00 year is a leap | |
399 | year. So we need to correct for Dec 31st comming out as | |
400 | the 366th day of the year. | |
401 | */ | |
402 | if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 ) | |
403 | local_tm->tm_yday--; | |
404 | ||
af9b2bf5 | 405 | assert(_check_tm(local_tm)); |
a272e669 MS |
406 | |
407 | return local_tm; | |
408 | } |