xref: /PHP-8.2/ext/date/lib/tm2unixtime.c (revision 629d7740)
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 		/* We calculate 'a + 1' first as 'start - *a - 1' causes an int64_t overflows if *a is
36 		 * LONG_MIN. 'start' is 0 in this context, and '0 - LONG_MIN > LONG_MAX'. */
37 		timelib_sll a_plus_1 = *a + 1;
38 
39 		*b -= (start - a_plus_1) / adj + 1;
40 
41 		/* This code add the extra 'adj' separately, as otherwise this can overflow int64_t in
42 		 * situations where *b is near LONG_MIN. */
43 		*a += adj * ((start - a_plus_1) / adj);
44 		*a += adj;
45 	}
46 	if (*a >= end) {
47 		*b += *a / adj;
48 		*a -= adj * (*a / adj);
49 	}
50 }
51 
inc_month(timelib_sll * y,timelib_sll * m)52 static void inc_month(timelib_sll *y, timelib_sll *m)
53 {
54 	(*m)++;
55 	if (*m > 12) {
56 		*m -= 12;
57 		(*y)++;
58 	}
59 }
60 
dec_month(timelib_sll * y,timelib_sll * m)61 static void dec_month(timelib_sll *y, timelib_sll *m)
62 {
63 	(*m)--;
64 	if (*m < 1) {
65 		*m += 12;
66 		(*y)--;
67 	}
68 }
69 
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)70 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)
71 {
72 	timelib_sll leapyear;
73 	timelib_sll month, year;
74 	timelib_sll days;
75 
76 	do_range_limit(1, 13, 12, base_m, base_y);
77 
78 	year = *base_y;
79 	month = *base_m;
80 
81 /*
82 	printf( "S: Y%d M%d   %d %d %d   %d\n", year, month, *y, *m, *d, days);
83 */
84 	if (!invert) {
85 		while (*d < 0) {
86 			dec_month(&year, &month);
87 			leapyear = timelib_is_leap(year);
88 			days = leapyear ? days_in_month_leap[month] : days_in_month[month];
89 
90 			/* printf( "I  Y%d M%d   %d %d %d   %d\n", year, month, *y, *m, *d, days); */
91 
92 			*d += days;
93 			(*m)--;
94 		}
95 	} else {
96 		while (*d < 0) {
97 			leapyear = timelib_is_leap(year);
98 			days = leapyear ? days_in_month_leap[month] : days_in_month[month];
99 
100 			/* printf( "I  Y%d M%d   %d %d %d   %d\n", year, month, *y, *m, *d, days); */
101 
102 			*d += days;
103 			(*m)--;
104 			inc_month(&year, &month);
105 		}
106 	}
107 	/*
108 	printf( "E: Y%d M%d   %d %d %d   %d\n", year, month, *y, *m, *d, days);
109 	*/
110 }
111 
do_range_limit_days(timelib_sll * y,timelib_sll * m,timelib_sll * d)112 static int do_range_limit_days(timelib_sll *y, timelib_sll *m, timelib_sll *d)
113 {
114 	timelib_sll leapyear;
115 	timelib_sll previous_month, previous_year;
116 	timelib_sll days_in_previous_month;
117 	int retval = 0;
118 	int *days_per_month_current_year;
119 
120 	/* can jump an entire leap year period quickly */
121 	if (*d >= DAYS_PER_ERA || *d <= -DAYS_PER_ERA) {
122 		*y += YEARS_PER_ERA * (*d / DAYS_PER_ERA);
123 		*d -= DAYS_PER_ERA * (*d / DAYS_PER_ERA);
124 	}
125 
126 	do_range_limit(1, 13, 12, m, y);
127 
128 	leapyear = timelib_is_leap(*y);
129 	days_per_month_current_year = leapyear ? days_in_month_leap : days_in_month;
130 
131 	while (*d <= 0 && *m > 0) {
132 		previous_month = (*m) - 1;
133 		if (previous_month < 1) {
134 			previous_month += 12;
135 			previous_year = (*y) - 1;
136 		} else {
137 			previous_year = (*y);
138 		}
139 		leapyear = timelib_is_leap(previous_year);
140 		days_in_previous_month = leapyear ? days_in_month_leap[previous_month] : days_in_month[previous_month];
141 
142 		*d += days_in_previous_month;
143 		(*m)--;
144 		retval = 1;
145 	}
146 	while (*d > 0 && *m <= 12 && *d > days_per_month_current_year[*m]) {
147 		*d -=  days_per_month_current_year[*m];
148 		(*m)++;
149 		retval = 1;
150 	}
151 	return retval;
152 }
153 
do_adjust_for_weekday(timelib_time * time)154 static void do_adjust_for_weekday(timelib_time* time)
155 {
156 	timelib_sll current_dow, difference;
157 
158 	current_dow = timelib_day_of_week(time->y, time->m, time->d);
159 	if (time->relative.weekday_behavior == 2)
160 	{
161 		/* To make "this week" work, where the current DOW is a "sunday" */
162 		if (current_dow == 0 && time->relative.weekday != 0) {
163 			time->relative.weekday -= 7;
164 		}
165 
166 		/* To make "sunday this week" work, where the current DOW is not a
167 		 * "sunday" */
168 		if (time->relative.weekday == 0 && current_dow != 0) {
169 			time->relative.weekday = 7;
170 		}
171 
172 		time->d -= current_dow;
173 		time->d += time->relative.weekday;
174 		return;
175 	}
176 	difference = time->relative.weekday - current_dow;
177 	if ((time->relative.d < 0 && difference < 0) || (time->relative.d >= 0 && difference <= -time->relative.weekday_behavior)) {
178 		difference += 7;
179 	}
180 	if (time->relative.weekday >= 0) {
181 		time->d += difference;
182 	} else {
183 		time->d -= (7 - (abs(time->relative.weekday) - current_dow));
184 	}
185 	time->relative.have_weekday_relative = 0;
186 }
187 
timelib_do_rel_normalize(timelib_time * base,timelib_rel_time * rt)188 void timelib_do_rel_normalize(timelib_time *base, timelib_rel_time *rt)
189 {
190 	do_range_limit(0, 1000000, 1000000, &rt->us, &rt->s);
191 	do_range_limit(0, 60, 60, &rt->s, &rt->i);
192 	do_range_limit(0, 60, 60, &rt->i, &rt->h);
193 	do_range_limit(0, 24, 24, &rt->h, &rt->d);
194 	do_range_limit(0, 12, 12, &rt->m, &rt->y);
195 
196 	do_range_limit_days_relative(&base->y, &base->m, &rt->y, &rt->m, &rt->d, rt->invert);
197 	do_range_limit(0, 12, 12, &rt->m, &rt->y);
198 }
199 
magic_date_calc(timelib_time * time)200 static void magic_date_calc(timelib_time *time)
201 {
202 	timelib_sll y, ddd, mi, mm, dd, g;
203 
204 	/* The algorithm doesn't work before the year 1 */
205 	if (time->d < -719498) {
206 		return;
207 	}
208 
209 	g = time->d + HINNANT_EPOCH_SHIFT - 1;
210 
211 	y = (10000 * g + 14780) / 3652425;
212 	ddd = g - ((365*y) + (y/4) - (y/100) + (y/400));
213 	if (ddd < 0) {
214 		y--;
215 		ddd = g - ((365*y) + (y/4) - (y/100) + (y/400));
216 	}
217 	mi = (100 * ddd + 52) / 3060;
218 	mm = ((mi + 2) % 12) + 1;
219 	y = y + (mi + 2) / 12;
220 	dd = ddd - ((mi * 306 + 5) / 10) + 1;
221 	time->y = y;
222 	time->m = mm;
223 	time->d = dd;
224 }
225 
timelib_do_normalize(timelib_time * time)226 void timelib_do_normalize(timelib_time* time)
227 {
228 	if (time->us != TIMELIB_UNSET) do_range_limit(0, 1000000, 1000000, &time->us, &time->s);
229 	if (time->s != TIMELIB_UNSET) do_range_limit(0, 60, 60, &time->s, &time->i);
230 	if (time->s != TIMELIB_UNSET) do_range_limit(0, 60, 60, &time->i, &time->h);
231 	if (time->s != TIMELIB_UNSET) do_range_limit(0, 24, 24, &time->h, &time->d);
232 	do_range_limit(1, 13, 12, &time->m, &time->y);
233 
234 	/* Short cut if we're doing things against the Epoch */
235 	if (time->y == 1970 && time->m == 1 && time->d != 1) {
236 		magic_date_calc(time);
237 	}
238 
239 	do {} while (do_range_limit_days(&time->y, &time->m, &time->d));
240 	do_range_limit(1, 13, 12, &time->m, &time->y);
241 }
242 
do_adjust_relative(timelib_time * time)243 static void do_adjust_relative(timelib_time* time)
244 {
245 	if (time->relative.have_weekday_relative) {
246 		do_adjust_for_weekday(time);
247 	}
248 	timelib_do_normalize(time);
249 
250 	if (time->have_relative) {
251 		time->us += time->relative.us;
252 
253 		time->s += time->relative.s;
254 		time->i += time->relative.i;
255 		time->h += time->relative.h;
256 
257 		time->d += time->relative.d;
258 		time->m += time->relative.m;
259 		time->y += time->relative.y;
260 	}
261 
262 	switch (time->relative.first_last_day_of) {
263 		case TIMELIB_SPECIAL_FIRST_DAY_OF_MONTH: /* first */
264 			time->d = 1;
265 			break;
266 		case TIMELIB_SPECIAL_LAST_DAY_OF_MONTH: /* last */
267 			time->d = 0;
268 			time->m++;
269 			break;
270 	}
271 
272 	timelib_do_normalize(time);
273 }
274 
do_adjust_special_weekday(timelib_time * time)275 static void do_adjust_special_weekday(timelib_time* time)
276 {
277 	timelib_sll count, dow, rem;
278 
279 	count = time->relative.special.amount;
280 	dow = timelib_day_of_week(time->y, time->m, time->d);
281 
282 	/* Add increments of 5 weekdays as a week, leaving the DOW unchanged. */
283 	time->d += (count / 5) * 7;
284 
285 	/* Deal with the remainder. */
286 	rem = (count % 5);
287 
288 	if (count > 0) {
289 		if (rem == 0) {
290 			/* Head back to Friday if we stop on the weekend. */
291 			if (dow == 0) {
292 				time->d -= 2;
293 			} else if (dow == 6) {
294 				time->d -= 1;
295 			}
296 		} else if (dow == 6) {
297 			/* We ended up on Saturday, but there's still work to do, so move
298 			 * to Sunday and continue from there. */
299 			time->d += 1;
300 		} else if (dow + rem > 5) {
301 			/* We're on a weekday, but we're going past Friday, so skip right
302 			 * over the weekend. */
303 			time->d += 2;
304 		}
305 	} else {
306 		/* Completely mirror the forward direction. This also covers the 0
307 		 * case, since if we start on the weekend, we want to move forward as
308 		 * if we stopped there while going backwards. */
309 		if (rem == 0) {
310 			if (dow == 6) {
311 				time->d += 2;
312 			} else if (dow == 0) {
313 				time->d += 1;
314 			}
315 		} else if (dow == 0) {
316 			time->d -= 1;
317 		} else if (dow + rem < 1) {
318 			time->d -= 2;
319 		}
320 	}
321 
322 	time->d += rem;
323 }
324 
do_adjust_special(timelib_time * time)325 static void do_adjust_special(timelib_time* time)
326 {
327 	if (time->relative.have_special_relative) {
328 		switch (time->relative.special.type) {
329 			case TIMELIB_SPECIAL_WEEKDAY:
330 				do_adjust_special_weekday(time);
331 				break;
332 		}
333 	}
334 	timelib_do_normalize(time);
335 	memset(&(time->relative.special), 0, sizeof(time->relative.special));
336 }
337 
do_adjust_special_early(timelib_time * time)338 static void do_adjust_special_early(timelib_time* time)
339 {
340 	if (time->relative.have_special_relative) {
341 		switch (time->relative.special.type) {
342 			case TIMELIB_SPECIAL_DAY_OF_WEEK_IN_MONTH:
343 				time->d = 1;
344 				time->m += time->relative.m;
345 				time->relative.m = 0;
346 				break;
347 			case TIMELIB_SPECIAL_LAST_DAY_OF_WEEK_IN_MONTH:
348 				time->d = 1;
349 				time->m += time->relative.m + 1;
350 				time->relative.m = 0;
351 				break;
352 		}
353 	}
354 	switch (time->relative.first_last_day_of) {
355 		case TIMELIB_SPECIAL_FIRST_DAY_OF_MONTH: /* first */
356 			time->d = 1;
357 			break;
358 		case TIMELIB_SPECIAL_LAST_DAY_OF_MONTH: /* last */
359 			time->d = 0;
360 			time->m++;
361 			break;
362 	}
363 	timelib_do_normalize(time);
364 }
365 
do_adjust_timezone(timelib_time * tz,timelib_tzinfo * tzi)366 static void do_adjust_timezone(timelib_time *tz, timelib_tzinfo *tzi)
367 {
368 	switch (tz->zone_type) {
369 		case TIMELIB_ZONETYPE_OFFSET:
370 
371 			tz->is_localtime = 1;
372 			tz->sse += -tz->z;
373 			return;
374 
375 		case TIMELIB_ZONETYPE_ABBR: {
376 
377 			tz->is_localtime = 1;
378 			tz->sse += (-tz->z - tz->dst * SECS_PER_HOUR);
379 			return;
380 		}
381 
382 		case TIMELIB_ZONETYPE_ID:
383 			tzi = tz->tz_info;
384 			TIMELIB_BREAK_INTENTIONALLY_MISSING
385 
386 		default: {
387 			/* No timezone in struct, fallback to reference if possible */
388 			int32_t              current_offset = 0;
389 			timelib_sll          current_transition_time = 0;
390 			unsigned int         current_is_dst = 0;
391 			int32_t              after_offset = 0;
392 			timelib_sll          after_transition_time = 0;
393 			timelib_sll          adjustment;
394 			int                  in_transition;
395 			int32_t              actual_offset;
396 			timelib_sll          actual_transition_time;
397 
398 			if (!tzi) {
399 				return;
400 			}
401 
402 			timelib_get_time_zone_offset_info(tz->sse, tzi, &current_offset, &current_transition_time, &current_is_dst);
403 			timelib_get_time_zone_offset_info(tz->sse - current_offset, tzi, &after_offset, &after_transition_time, NULL);
404 			actual_offset = after_offset;
405 			actual_transition_time = after_transition_time;
406 			if (current_offset == after_offset && tz->have_zone) {
407 				/* Make sure we're not missing a DST change because we don't know the actual offset yet */
408 				if (current_offset >= 0 && tz->dst && !current_is_dst) {
409 						/* 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 */
410 						int32_t              earlier_offset;
411 						timelib_sll          earlier_transition_time;
412 						timelib_get_time_zone_offset_info(tz->sse - current_offset - 7200, tzi, &earlier_offset, &earlier_transition_time, NULL);
413 						if ((earlier_offset != after_offset) && (tz->sse - earlier_offset < after_transition_time)) {
414 								/* Looking behind a bit clarified the actual offset to use */
415 								actual_offset = earlier_offset;
416 								actual_transition_time = earlier_transition_time;
417 						}
418 				} else if (current_offset <= 0 && current_is_dst && !tz->dst) {
419 						/* Timezone west of UTC, so the local time, interpreted as UTC, leaves DST (as defined in the actual timezone) after the actual local time */
420 						int32_t              later_offset;
421 						timelib_sll          later_transition_time;
422 						timelib_get_time_zone_offset_info(tz->sse - current_offset + 7200, tzi, &later_offset, &later_transition_time, NULL);
423 						if ((later_offset != after_offset) && (tz->sse - later_offset >= later_transition_time)) {
424 								/* Looking ahead a bit clarified the actual offset to use */
425 								actual_offset = later_offset;
426 								actual_transition_time = later_transition_time;
427 						}
428 				}
429 			}
430 
431 			tz->is_localtime = 1;
432 
433 			in_transition = (
434 				actual_transition_time != INT64_MIN &&
435 				((tz->sse - actual_offset) >= (actual_transition_time + (current_offset - actual_offset))) &&
436 				((tz->sse - actual_offset) < actual_transition_time)
437 			);
438 
439 			if ((current_offset != actual_offset) && !in_transition) {
440 				adjustment = -actual_offset;
441 			} else {
442 				adjustment = -current_offset;
443 			}
444 
445 			tz->sse += adjustment;
446 			timelib_set_timezone(tz, tzi);
447 			return;
448 		}
449 	}
450 	return;
451 }
452 
timelib_epoch_days_from_time(timelib_time * time)453 timelib_sll timelib_epoch_days_from_time(timelib_time *time)
454 {
455 	timelib_sll y = time->y; // Make copy, as we don't want to change the original one
456 	timelib_sll era, year_of_era, day_of_year, day_of_era;
457 
458 	y -= time->m <= 2;
459 	era = (y >= 0 ? y : y - 399) / YEARS_PER_ERA;
460 	year_of_era = y - era * YEARS_PER_ERA;                                                        // [0, 399]
461 	day_of_year = (153 * (time->m + (time->m > 2 ? -3 : 9)) + 2)/5 + time->d - 1;                 // [0, 365]
462 	day_of_era = year_of_era * DAYS_PER_YEAR + year_of_era / 4 - year_of_era / 100 + day_of_year; // [0, 146096]
463 
464 	return era * DAYS_PER_ERA + day_of_era - HINNANT_EPOCH_SHIFT;
465 }
466 
timelib_update_ts(timelib_time * time,timelib_tzinfo * tzi)467 void timelib_update_ts(timelib_time* time, timelib_tzinfo* tzi)
468 {
469 	do_adjust_special_early(time);
470 	do_adjust_relative(time);
471 	do_adjust_special(time);
472 
473 	/* You might be wondering, why this code does this in two steps. This is because
474 	 * timelib_epoch_days_from_time(time) * SECS_PER_DAY with the lowest limit of
475 	 * timelib_epoch_days_from_time() is less than the range of an int64_t. This then overflows. In
476 	 * order to be able to still allow for any time in that day that only halfly fits in the int64_t
477 	 * range, we add the time element first, which is always positive, and then twice half the value
478 	 * of the earliest day as expressed as unix timestamp. */
479 	time->sse = timelib_hms_to_seconds(time->h, time->i, time->s);
480 	time->sse += timelib_epoch_days_from_time(time) * (SECS_PER_DAY / 2);
481 	time->sse += timelib_epoch_days_from_time(time) * (SECS_PER_DAY / 2);
482 
483 	// This modifies time->sse, if needed
484 	do_adjust_timezone(time, tzi);
485 
486 	time->sse_uptodate = 1;
487 	time->have_relative = time->relative.have_weekday_relative = time->relative.have_special_relative = time->relative.first_last_day_of = 0;
488 }
489 
490 #if 0
491 int main(void)
492 {
493 	timelib_sll res;
494 	timelib_time time;
495 
496 	time = timelib_strtotime("10 Feb 2005 06:07:03 PM CET"); /* 1108055223 */
497 	printf ("%04d-%02d-%02d %02d:%02d:%02d.%-5d %+04d %1d",
498 		time.y, time.m, time.d, time.h, time.i, time.s, time.f, time.z, time.dst);
499 	if (time.have_relative) {
500 		printf ("%3dY %3dM %3dD / %3dH %3dM %3dS",
501 			time.relative.y, time.relative.m, time.relative.d, time.relative.h, time.relative.i, time.relative.s);
502 	}
503 	if (time.have_weekday_relative) {
504 		printf (" / %d", time.relative.weekday);
505 	}
506 	res = time2unixtime(&time);
507 	printf("%Ld\n", res);
508 
509 	return 0;
510 }
511 #endif
512