1 /*
2 * The MIT License (MIT)
3 *
4 * Copyright (c) 2015-2019 Derick Rethans
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #include "timelib.h"
26 #include "timelib_private.h"
27
28 /* dec jan feb mrt apr may jun jul aug sep oct nov dec */
29 static int days_in_month_leap[13] = { 31, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
30 static int days_in_month[13] = { 31, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
31
do_range_limit(timelib_sll start,timelib_sll end,timelib_sll adj,timelib_sll * a,timelib_sll * b)32 static void do_range_limit(timelib_sll start, timelib_sll end, timelib_sll adj, timelib_sll *a, timelib_sll *b)
33 {
34 if (*a < start) {
35 *b -= (start - *a - 1) / adj + 1;
36 *a += adj * ((start - *a - 1) / adj + 1);
37 }
38 if (*a >= end) {
39 *b += *a / adj;
40 *a -= adj * (*a / adj);
41 }
42 }
43
inc_month(timelib_sll * y,timelib_sll * m)44 static void inc_month(timelib_sll *y, timelib_sll *m)
45 {
46 (*m)++;
47 if (*m > 12) {
48 *m -= 12;
49 (*y)++;
50 }
51 }
52
dec_month(timelib_sll * y,timelib_sll * m)53 static void dec_month(timelib_sll *y, timelib_sll *m)
54 {
55 (*m)--;
56 if (*m < 1) {
57 *m += 12;
58 (*y)--;
59 }
60 }
61
do_range_limit_days_relative(timelib_sll * base_y,timelib_sll * base_m,timelib_sll * y,timelib_sll * m,timelib_sll * d,timelib_sll invert)62 static void do_range_limit_days_relative(timelib_sll *base_y, timelib_sll *base_m, timelib_sll *y, timelib_sll *m, timelib_sll *d, timelib_sll invert)
63 {
64 timelib_sll leapyear;
65 timelib_sll month, year;
66 timelib_sll days;
67
68 do_range_limit(1, 13, 12, base_m, base_y);
69
70 year = *base_y;
71 month = *base_m;
72
73 /*
74 printf( "S: Y%d M%d %d %d %d %d\n", year, month, *y, *m, *d, days);
75 */
76 if (!invert) {
77 while (*d < 0) {
78 dec_month(&year, &month);
79 leapyear = timelib_is_leap(year);
80 days = leapyear ? days_in_month_leap[month] : days_in_month[month];
81
82 /* printf( "I Y%d M%d %d %d %d %d\n", year, month, *y, *m, *d, days); */
83
84 *d += days;
85 (*m)--;
86 }
87 } else {
88 while (*d < 0) {
89 leapyear = timelib_is_leap(year);
90 days = leapyear ? days_in_month_leap[month] : days_in_month[month];
91
92 /* printf( "I Y%d M%d %d %d %d %d\n", year, month, *y, *m, *d, days); */
93
94 *d += days;
95 (*m)--;
96 inc_month(&year, &month);
97 }
98 }
99 /*
100 printf( "E: Y%d M%d %d %d %d %d\n", year, month, *y, *m, *d, days);
101 */
102 }
103
do_range_limit_days(timelib_sll * y,timelib_sll * m,timelib_sll * d)104 static int do_range_limit_days(timelib_sll *y, timelib_sll *m, timelib_sll *d)
105 {
106 timelib_sll leapyear;
107 timelib_sll days_this_month;
108 timelib_sll last_month, last_year;
109 timelib_sll days_last_month;
110
111 /* can jump an entire leap year period quickly */
112 if (*d >= DAYS_PER_ERA || *d <= -DAYS_PER_ERA) {
113 *y += YEARS_PER_ERA * (*d / DAYS_PER_ERA);
114 *d -= DAYS_PER_ERA * (*d / DAYS_PER_ERA);
115 }
116
117 do_range_limit(1, 13, 12, m, y);
118
119 leapyear = timelib_is_leap(*y);
120 days_this_month = leapyear ? days_in_month_leap[*m] : days_in_month[*m];
121 last_month = (*m) - 1;
122
123 if (last_month < 1) {
124 last_month += 12;
125 last_year = (*y) - 1;
126 } else {
127 last_year = (*y);
128 }
129 leapyear = timelib_is_leap(last_year);
130 days_last_month = leapyear ? days_in_month_leap[last_month] : days_in_month[last_month];
131
132 if (*d <= 0) {
133 *d += days_last_month;
134 (*m)--;
135 return 1;
136 }
137 if (*d > days_this_month) {
138 *d -= days_this_month;
139 (*m)++;
140 return 1;
141 }
142 return 0;
143 }
144
do_adjust_for_weekday(timelib_time * time)145 static void do_adjust_for_weekday(timelib_time* time)
146 {
147 timelib_sll current_dow, difference;
148
149 current_dow = timelib_day_of_week(time->y, time->m, time->d);
150 if (time->relative.weekday_behavior == 2)
151 {
152 /* To make "this week" work, where the current DOW is a "sunday" */
153 if (current_dow == 0 && time->relative.weekday != 0) {
154 time->relative.weekday -= 7;
155 }
156
157 /* To make "sunday this week" work, where the current DOW is not a
158 * "sunday" */
159 if (time->relative.weekday == 0 && current_dow != 0) {
160 time->relative.weekday = 7;
161 }
162
163 time->d -= current_dow;
164 time->d += time->relative.weekday;
165 return;
166 }
167 difference = time->relative.weekday - current_dow;
168 if ((time->relative.d < 0 && difference < 0) || (time->relative.d >= 0 && difference <= -time->relative.weekday_behavior)) {
169 difference += 7;
170 }
171 if (time->relative.weekday >= 0) {
172 time->d += difference;
173 } else {
174 time->d -= (7 - (abs(time->relative.weekday) - current_dow));
175 }
176 time->relative.have_weekday_relative = 0;
177 }
178
timelib_do_rel_normalize(timelib_time * base,timelib_rel_time * rt)179 void timelib_do_rel_normalize(timelib_time *base, timelib_rel_time *rt)
180 {
181 do_range_limit(0, 1000000, 1000000, &rt->us, &rt->s);
182 do_range_limit(0, 60, 60, &rt->s, &rt->i);
183 do_range_limit(0, 60, 60, &rt->i, &rt->h);
184 do_range_limit(0, 24, 24, &rt->h, &rt->d);
185 do_range_limit(0, 12, 12, &rt->m, &rt->y);
186
187 do_range_limit_days_relative(&base->y, &base->m, &rt->y, &rt->m, &rt->d, rt->invert);
188 do_range_limit(0, 12, 12, &rt->m, &rt->y);
189 }
190
magic_date_calc(timelib_time * time)191 static void magic_date_calc(timelib_time *time)
192 {
193 timelib_sll y, ddd, mi, mm, dd, g;
194
195 /* The algorithm doesn't work before the year 1 */
196 if (time->d < -719498) {
197 return;
198 }
199
200 g = time->d + HINNANT_EPOCH_SHIFT - 1;
201
202 y = (10000 * g + 14780) / 3652425;
203 ddd = g - ((365*y) + (y/4) - (y/100) + (y/400));
204 if (ddd < 0) {
205 y--;
206 ddd = g - ((365*y) + (y/4) - (y/100) + (y/400));
207 }
208 mi = (100 * ddd + 52) / 3060;
209 mm = ((mi + 2) % 12) + 1;
210 y = y + (mi + 2) / 12;
211 dd = ddd - ((mi * 306 + 5) / 10) + 1;
212 time->y = y;
213 time->m = mm;
214 time->d = dd;
215 }
216
timelib_do_normalize(timelib_time * time)217 void timelib_do_normalize(timelib_time* time)
218 {
219 if (time->us != TIMELIB_UNSET) do_range_limit(0, 1000000, 1000000, &time->us, &time->s);
220 if (time->s != TIMELIB_UNSET) do_range_limit(0, 60, 60, &time->s, &time->i);
221 if (time->s != TIMELIB_UNSET) do_range_limit(0, 60, 60, &time->i, &time->h);
222 if (time->s != TIMELIB_UNSET) do_range_limit(0, 24, 24, &time->h, &time->d);
223 do_range_limit(1, 13, 12, &time->m, &time->y);
224
225 /* Short cut if we're doing things against the Epoch */
226 if (time->y == 1970 && time->m == 1 && time->d != 1) {
227 magic_date_calc(time);
228 }
229
230 do {} while (do_range_limit_days(&time->y, &time->m, &time->d));
231 do_range_limit(1, 13, 12, &time->m, &time->y);
232 }
233
do_adjust_relative(timelib_time * time)234 static void do_adjust_relative(timelib_time* time)
235 {
236 if (time->relative.have_weekday_relative) {
237 do_adjust_for_weekday(time);
238 }
239 timelib_do_normalize(time);
240
241 if (time->have_relative) {
242 time->us += time->relative.us;
243
244 time->s += time->relative.s;
245 time->i += time->relative.i;
246 time->h += time->relative.h;
247
248 time->d += time->relative.d;
249 time->m += time->relative.m;
250 time->y += time->relative.y;
251 }
252
253 switch (time->relative.first_last_day_of) {
254 case TIMELIB_SPECIAL_FIRST_DAY_OF_MONTH: /* first */
255 time->d = 1;
256 break;
257 case TIMELIB_SPECIAL_LAST_DAY_OF_MONTH: /* last */
258 time->d = 0;
259 time->m++;
260 break;
261 }
262
263 timelib_do_normalize(time);
264 }
265
do_adjust_special_weekday(timelib_time * time)266 static void do_adjust_special_weekday(timelib_time* time)
267 {
268 timelib_sll count, dow, rem;
269
270 count = time->relative.special.amount;
271 dow = timelib_day_of_week(time->y, time->m, time->d);
272
273 /* Add increments of 5 weekdays as a week, leaving the DOW unchanged. */
274 time->d += (count / 5) * 7;
275
276 /* Deal with the remainder. */
277 rem = (count % 5);
278
279 if (count > 0) {
280 if (rem == 0) {
281 /* Head back to Friday if we stop on the weekend. */
282 if (dow == 0) {
283 time->d -= 2;
284 } else if (dow == 6) {
285 time->d -= 1;
286 }
287 } else if (dow == 6) {
288 /* We ended up on Saturday, but there's still work to do, so move
289 * to Sunday and continue from there. */
290 time->d += 1;
291 } else if (dow + rem > 5) {
292 /* We're on a weekday, but we're going past Friday, so skip right
293 * over the weekend. */
294 time->d += 2;
295 }
296 } else {
297 /* Completely mirror the forward direction. This also covers the 0
298 * case, since if we start on the weekend, we want to move forward as
299 * if we stopped there while going backwards. */
300 if (rem == 0) {
301 if (dow == 6) {
302 time->d += 2;
303 } else if (dow == 0) {
304 time->d += 1;
305 }
306 } else if (dow == 0) {
307 time->d -= 1;
308 } else if (dow + rem < 1) {
309 time->d -= 2;
310 }
311 }
312
313 time->d += rem;
314 }
315
do_adjust_special(timelib_time * time)316 static void do_adjust_special(timelib_time* time)
317 {
318 if (time->relative.have_special_relative) {
319 switch (time->relative.special.type) {
320 case TIMELIB_SPECIAL_WEEKDAY:
321 do_adjust_special_weekday(time);
322 break;
323 }
324 }
325 timelib_do_normalize(time);
326 memset(&(time->relative.special), 0, sizeof(time->relative.special));
327 }
328
do_adjust_special_early(timelib_time * time)329 static void do_adjust_special_early(timelib_time* time)
330 {
331 if (time->relative.have_special_relative) {
332 switch (time->relative.special.type) {
333 case TIMELIB_SPECIAL_DAY_OF_WEEK_IN_MONTH:
334 time->d = 1;
335 time->m += time->relative.m;
336 time->relative.m = 0;
337 break;
338 case TIMELIB_SPECIAL_LAST_DAY_OF_WEEK_IN_MONTH:
339 time->d = 1;
340 time->m += time->relative.m + 1;
341 time->relative.m = 0;
342 break;
343 }
344 }
345 switch (time->relative.first_last_day_of) {
346 case TIMELIB_SPECIAL_FIRST_DAY_OF_MONTH: /* first */
347 time->d = 1;
348 break;
349 case TIMELIB_SPECIAL_LAST_DAY_OF_MONTH: /* last */
350 time->d = 0;
351 time->m++;
352 break;
353 }
354 timelib_do_normalize(time);
355 }
356
do_adjust_timezone(timelib_time * tz,timelib_tzinfo * tzi)357 static void do_adjust_timezone(timelib_time *tz, timelib_tzinfo *tzi)
358 {
359 switch (tz->zone_type) {
360 case TIMELIB_ZONETYPE_OFFSET:
361
362 tz->is_localtime = 1;
363 tz->sse += -tz->z;
364 return;
365
366 case TIMELIB_ZONETYPE_ABBR: {
367
368 tz->is_localtime = 1;
369 tz->sse += (-tz->z - tz->dst * SECS_PER_HOUR);
370 return;
371 }
372
373 case TIMELIB_ZONETYPE_ID:
374 tzi = tz->tz_info;
375 TIMELIB_BREAK_INTENTIONALLY_MISSING
376
377 default: {
378 /* No timezone in struct, fallback to reference if possible */
379 timelib_time_offset *current, *after;
380 timelib_sll adjustment;
381 int in_transition;
382 int32_t actual_offset;
383 timelib_sll actual_transition_time;
384
385 if (!tzi) {
386 return;
387 }
388
389 current = timelib_get_time_zone_info(tz->sse, tzi);
390 after = timelib_get_time_zone_info(tz->sse - current->offset, tzi);
391 actual_offset = after->offset;
392 actual_transition_time = after->transition_time;
393 if (current->offset == after->offset && tz->have_zone) {
394 /* Make sure we're not missing a DST change because we don't know the actual offset yet */
395 if (current->offset >= 0 && tz->dst && !current->is_dst) {
396 /* Timezone or its DST at or east of UTC, so the local time, interpreted as UTC, leaves DST (as defined in the actual timezone) before the actual local time */
397 timelib_time_offset *earlier;
398 earlier = timelib_get_time_zone_info(tz->sse - current->offset - 7200, tzi);
399 if ((earlier->offset != after->offset) && (tz->sse - earlier->offset < after->transition_time)) {
400 /* Looking behind a bit clarified the actual offset to use */
401 actual_offset = earlier->offset;
402 actual_transition_time = earlier->transition_time;
403 }
404 timelib_time_offset_dtor(earlier);
405 } else if (current->offset <= 0 && current->is_dst && !tz->dst) {
406 /* Timezone west of UTC, so the local time, interpreted as UTC, leaves DST (as defined in the actual timezone) after the actual local time */
407 timelib_time_offset *later;
408 later = timelib_get_time_zone_info(tz->sse - current->offset + 7200, tzi);
409 if ((later->offset != after->offset) && (tz->sse - later->offset >= later->transition_time)) {
410 /* Looking ahead a bit clarified the actual offset to use */
411 actual_offset = later->offset;
412 actual_transition_time = later->transition_time;
413 }
414 timelib_time_offset_dtor(later);
415 }
416 }
417
418 tz->is_localtime = 1;
419
420 in_transition = (
421 ((tz->sse - actual_offset) >= (actual_transition_time + (current->offset - actual_offset))) &&
422 ((tz->sse - actual_offset) < actual_transition_time)
423 );
424
425 if ((current->offset != actual_offset) && !in_transition) {
426 adjustment = -actual_offset;
427 } else {
428 adjustment = -current->offset;
429 }
430 timelib_time_offset_dtor(current);
431 timelib_time_offset_dtor(after);
432
433 tz->sse += adjustment;
434 timelib_set_timezone(tz, tzi);
435 return;
436 }
437 }
438 return;
439 }
440
timelib_epoch_days_from_time(timelib_time * time)441 timelib_sll timelib_epoch_days_from_time(timelib_time *time)
442 {
443 timelib_sll y = time->y; // Make copy, as we don't want to change the original one
444 timelib_sll era, year_of_era, day_of_year, day_of_era;
445
446 y -= time->m <= 2;
447 era = (y >= 0 ? y : y - 399) / YEARS_PER_ERA;
448 year_of_era = y - era * YEARS_PER_ERA; // [0, 399]
449 day_of_year = (153 * (time->m + (time->m > 2 ? -3 : 9)) + 2)/5 + time->d - 1; // [0, 365]
450 day_of_era = year_of_era * DAYS_PER_YEAR + year_of_era / 4 - year_of_era / 100 + day_of_year; // [0, 146096]
451
452 return era * DAYS_PER_ERA + day_of_era - HINNANT_EPOCH_SHIFT;
453 }
454
timelib_update_ts(timelib_time * time,timelib_tzinfo * tzi)455 void timelib_update_ts(timelib_time* time, timelib_tzinfo* tzi)
456 {
457 do_adjust_special_early(time);
458 do_adjust_relative(time);
459 do_adjust_special(time);
460
461 time->sse =
462 (timelib_epoch_days_from_time(time) * SECS_PER_DAY) +
463 timelib_hms_to_seconds(time->h, time->i, time->s);
464
465 // This modifies time->sse, if needed
466 do_adjust_timezone(time, tzi);
467
468 time->sse_uptodate = 1;
469 time->have_relative = time->relative.have_weekday_relative = time->relative.have_special_relative = time->relative.first_last_day_of = 0;
470 }
471
472 #if 0
473 int main(void)
474 {
475 timelib_sll res;
476 timelib_time time;
477
478 time = timelib_strtotime("10 Feb 2005 06:07:03 PM CET"); /* 1108055223 */
479 printf ("%04d-%02d-%02d %02d:%02d:%02d.%-5d %+04d %1d",
480 time.y, time.m, time.d, time.h, time.i, time.s, time.f, time.z, time.dst);
481 if (time.have_relative) {
482 printf ("%3dY %3dM %3dD / %3dH %3dM %3dS",
483 time.relative.y, time.relative.m, time.relative.d, time.relative.h, time.relative.i, time.relative.s);
484 }
485 if (time.have_weekday_relative) {
486 printf (" / %d", time.relative.weekday);
487 }
488 res = time2unixtime(&time);
489 printf("%Ld\n", res);
490
491 return 0;
492 }
493 #endif
494
