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 #include <math.h>
28
swap_times(timelib_time ** one,timelib_time ** two,timelib_rel_time * rt)29 static void swap_times(timelib_time **one, timelib_time **two, timelib_rel_time *rt)
30 {
31 timelib_time *swp;
32
33 swp = *two;
34 *two = *one;
35 *one = swp;
36 rt->invert = 1;
37 }
38
sort_old_to_new(timelib_time ** one,timelib_time ** two,timelib_rel_time * rt)39 static void sort_old_to_new(timelib_time **one, timelib_time **two, timelib_rel_time *rt)
40 {
41 /* Check whether date/times need to be inverted. If both times are
42 * TIMELIB_ZONETYPE_ID times with the same TZID, we use the y-s + us fields. */
43 if (
44 (*one)->zone_type == TIMELIB_ZONETYPE_ID &&
45 (*two)->zone_type == TIMELIB_ZONETYPE_ID &&
46 (strcmp((*one)->tz_info->name, (*two)->tz_info->name) == 0)
47 ) {
48 if (
49 ((*one)->y > (*two)->y) ||
50 ((*one)->y == (*two)->y && (*one)->m > (*two)->m) ||
51 ((*one)->y == (*two)->y && (*one)->m == (*two)->m && (*one)->d > (*two)->d) ||
52 ((*one)->y == (*two)->y && (*one)->m == (*two)->m && (*one)->d == (*two)->d && (*one)->h > (*two)->h) ||
53 ((*one)->y == (*two)->y && (*one)->m == (*two)->m && (*one)->d == (*two)->d && (*one)->h == (*two)->h && (*one)->i > (*two)->i) ||
54 ((*one)->y == (*two)->y && (*one)->m == (*two)->m && (*one)->d == (*two)->d && (*one)->h == (*two)->h && (*one)->i == (*two)->i && (*one)->s > (*two)->s) ||
55 ((*one)->y == (*two)->y && (*one)->m == (*two)->m && (*one)->d == (*two)->d && (*one)->h == (*two)->h && (*one)->i == (*two)->i && (*one)->s == (*two)->s && (*one)->us > (*two)->us)
56 ) {
57 swap_times(one, two, rt);
58 }
59 return;
60 }
61
62 /* Fall back to using the SSE instead to rearrange */
63 if (
64 ((*one)->sse > (*two)->sse) ||
65 ((*one)->sse == (*two)->sse && (*one)->us > (*two)->us)
66 ) {
67 swap_times(one, two, rt);
68 }
69 }
70
timelib_diff_with_tzid(timelib_time * one,timelib_time * two)71 static timelib_rel_time *timelib_diff_with_tzid(timelib_time *one, timelib_time *two)
72 {
73 timelib_rel_time *rt;
74 timelib_sll dst_corr = 0, dst_h_corr = 0, dst_m_corr = 0;
75 int32_t trans_offset;
76 timelib_sll trans_transition_time;
77
78 rt = timelib_rel_time_ctor();
79 rt->invert = 0;
80
81 sort_old_to_new(&one, &two, rt);
82
83 /* Calculate correction for UTC offset changes between first and second SSE */
84 dst_corr = two->z - one->z;
85 dst_h_corr = dst_corr / 3600;
86 dst_m_corr = (dst_corr % 3600) / 60;
87
88 rt->y = two->y - one->y;
89 rt->m = two->m - one->m;
90 rt->d = two->d - one->d;
91 rt->h = two->h - one->h;
92 rt->i = two->i - one->i;
93 rt->s = two->s - one->s;
94 rt->us = two->us - one->us;
95
96 rt->days = timelib_diff_days(one, two);
97
98 /* Fall Back: Cater for transition period, where rt->invert is 0, but there are negative numbers */
99 if (two->sse < one->sse) {
100 timelib_sll flipped = llabs((rt->i * 60) + (rt->s) - dst_corr);
101 rt->h = flipped / SECS_PER_HOUR;
102 rt->i = (flipped - rt->h * SECS_PER_HOUR) / 60;
103 rt->s = flipped % 60;
104
105 rt->invert = 1 - rt->invert;
106 }
107
108 timelib_do_rel_normalize(rt->invert ? one : two, rt);
109
110 if (one->dst == 1 && two->dst == 0) { /* Fall Back */
111 if (two->tz_info) {
112 if ((two->sse - one->sse + dst_corr) < SECS_PER_DAY) {
113 rt->h -= dst_h_corr;
114 rt->i -= dst_m_corr;
115 }
116 }
117 } else if (one->dst == 0 && two->dst == 1) { /* Spring Forward */
118 if (two->tz_info) {
119 int success = timelib_get_time_zone_offset_info(two->sse, two->tz_info, &trans_offset, &trans_transition_time, NULL);
120
121 if (
122 success &&
123 !((one->sse + SECS_PER_DAY > trans_transition_time) && (one->sse + SECS_PER_DAY <= (trans_transition_time + dst_corr))) &&
124 two->sse >= trans_transition_time &&
125 ((two->sse - one->sse + dst_corr) % SECS_PER_DAY) > (two->sse - trans_transition_time)
126 ) {
127 rt->h -= dst_h_corr;
128 rt->i -= dst_m_corr;
129 }
130 }
131 } else if (two->sse - one->sse >= SECS_PER_DAY) {
132 /* Check whether we're in the period to the next transition time */
133 if (timelib_get_time_zone_offset_info(two->sse - two->z, two->tz_info, &trans_offset, &trans_transition_time, NULL)) {
134 dst_corr = one->z - trans_offset;
135
136 if (two->sse >= trans_transition_time - dst_corr && two->sse < trans_transition_time) {
137 rt->d--;
138 rt->h = 24;
139 }
140 }
141 }
142
143 return rt;
144 }
145
timelib_diff(timelib_time * one,timelib_time * two)146 timelib_rel_time *timelib_diff(timelib_time *one, timelib_time *two)
147 {
148 timelib_rel_time *rt;
149
150 if (one->zone_type == TIMELIB_ZONETYPE_ID && two->zone_type == TIMELIB_ZONETYPE_ID && strcmp(one->tz_info->name, two->tz_info->name) == 0) {
151 return timelib_diff_with_tzid(one, two);
152 }
153
154 rt = timelib_rel_time_ctor();
155 rt->invert = 0;
156
157 sort_old_to_new(&one, &two, rt);
158
159 rt->y = two->y - one->y;
160 rt->m = two->m - one->m;
161 rt->d = two->d - one->d;
162 rt->h = two->h - one->h;
163 if (one->zone_type != TIMELIB_ZONETYPE_ID) {
164 rt->h = rt->h + one->dst;
165 }
166 if (two->zone_type != TIMELIB_ZONETYPE_ID) {
167 rt->h = rt->h - two->dst;
168 }
169 rt->i = two->i - one->i;
170 rt->s = two->s - one->s - two->z + one->z;
171 rt->us = two->us - one->us;
172
173 rt->days = timelib_diff_days(one, two);
174
175 timelib_do_rel_normalize(rt->invert ? one : two, rt);
176
177 return rt;
178 }
179
180
timelib_diff_days(timelib_time * one,timelib_time * two)181 int timelib_diff_days(timelib_time *one, timelib_time *two)
182 {
183 int days = 0;
184
185 if (timelib_same_timezone(one, two)) {
186 timelib_time *earliest, *latest;
187 double earliest_time, latest_time;
188
189 if (timelib_time_compare(one, two) < 0) {
190 earliest = one;
191 latest = two;
192 } else {
193 earliest = two;
194 latest = one;
195 }
196 timelib_hmsf_to_decimal_hour(earliest->h, earliest->i, earliest->s, earliest->us, &earliest_time);
197 timelib_hmsf_to_decimal_hour(latest->h, latest->i, latest->s, latest->us, &latest_time);
198
199 days = llabs(timelib_epoch_days_from_time(one) - timelib_epoch_days_from_time(two));
200 if (latest_time < earliest_time && days > 0) {
201 days--;
202 }
203 } else {
204 days = fabs(floor(one->sse - two->sse) / 86400);
205 }
206
207 return days;
208 }
209
210
timelib_add(timelib_time * old_time,timelib_rel_time * interval)211 timelib_time *timelib_add(timelib_time *old_time, timelib_rel_time *interval)
212 {
213 int bias = 1;
214 timelib_time *t = timelib_time_clone(old_time);
215
216 if (interval->have_weekday_relative || interval->have_special_relative) {
217 memcpy(&t->relative, interval, sizeof(timelib_rel_time));
218 } else {
219 if (interval->invert) {
220 bias = -1;
221 }
222 memset(&t->relative, 0, sizeof(timelib_rel_time));
223 t->relative.y = interval->y * bias;
224 t->relative.m = interval->m * bias;
225 t->relative.d = interval->d * bias;
226 t->relative.h = interval->h * bias;
227 t->relative.i = interval->i * bias;
228 t->relative.s = interval->s * bias;
229 t->relative.us = interval->us * bias;
230 }
231 t->have_relative = 1;
232 t->sse_uptodate = 0;
233
234 timelib_update_ts(t, NULL);
235
236 timelib_update_from_sse(t);
237 t->have_relative = 0;
238
239 return t;
240 }
241
timelib_sub(timelib_time * old_time,timelib_rel_time * interval)242 timelib_time *timelib_sub(timelib_time *old_time, timelib_rel_time *interval)
243 {
244 int bias = 1;
245 timelib_time *t = timelib_time_clone(old_time);
246
247 if (interval->invert) {
248 bias = -1;
249 }
250
251 memset(&t->relative, 0, sizeof(timelib_rel_time));
252 t->relative.y = 0 - (interval->y * bias);
253 t->relative.m = 0 - (interval->m * bias);
254 t->relative.d = 0 - (interval->d * bias);
255 t->relative.h = 0 - (interval->h * bias);
256 t->relative.i = 0 - (interval->i * bias);
257 t->relative.s = 0 - (interval->s * bias);
258 t->relative.us = 0 - (interval->us * bias);
259 t->have_relative = 1;
260 t->sse_uptodate = 0;
261
262 timelib_update_ts(t, NULL);
263
264 timelib_update_from_sse(t);
265
266 t->have_relative = 0;
267
268 return t;
269 }
270
do_range_limit(timelib_sll start,timelib_sll end,timelib_sll adj,timelib_sll * a,timelib_sll * b)271 static void do_range_limit(timelib_sll start, timelib_sll end, timelib_sll adj, timelib_sll *a, timelib_sll *b)
272 {
273 if (*a < start) {
274 *b -= (start - *a - 1) / adj + 1;
275 *a += adj * ((start - *a - 1) / adj + 1);
276 }
277 if (*a >= end) {
278 *b += *a / adj;
279 *a -= adj * (*a / adj);
280 }
281 }
282
283
timelib_add_wall(timelib_time * old_time,timelib_rel_time * interval)284 timelib_time *timelib_add_wall(timelib_time *old_time, timelib_rel_time *interval)
285 {
286 int bias = 1;
287 timelib_time *t = timelib_time_clone(old_time);
288
289 t->have_relative = 1;
290 t->sse_uptodate = 0;
291
292 if (interval->have_weekday_relative || interval->have_special_relative) {
293 memcpy(&t->relative, interval, sizeof(timelib_rel_time));
294
295 timelib_update_ts(t, NULL);
296
297 timelib_update_from_sse(t);
298 } else {
299 if (interval->invert) {
300 bias = -1;
301 }
302 memset(&t->relative, 0, sizeof(timelib_rel_time));
303 t->relative.y = interval->y * bias;
304 t->relative.m = interval->m * bias;
305 t->relative.d = interval->d * bias;
306
307 if (t->relative.y || t->relative.m || t->relative.d) {
308 timelib_update_ts(t, NULL);
309 }
310
311 if (interval->us == 0) {
312 t->sse += bias * timelib_hms_to_seconds(interval->h, interval->i, interval->s);
313 timelib_update_from_sse(t);
314 } else {
315 timelib_rel_time *temp_interval = timelib_rel_time_clone(interval);
316
317 do_range_limit(0, 1000000, 1000000, &temp_interval->us, &temp_interval->s);
318 t->sse += bias * timelib_hms_to_seconds(temp_interval->h, temp_interval->i, temp_interval->s);
319 timelib_update_from_sse(t);
320 t->us += temp_interval->us * bias;
321
322 timelib_do_normalize(t);
323 timelib_update_ts(t, NULL);
324
325 timelib_rel_time_dtor(temp_interval);
326 }
327 timelib_do_normalize(t);
328 }
329
330 if (t->zone_type == TIMELIB_ZONETYPE_ID) {
331 timelib_set_timezone(t, t->tz_info);
332 }
333 t->have_relative = 0;
334
335 return t;
336 }
337
timelib_sub_wall(timelib_time * old_time,timelib_rel_time * interval)338 timelib_time *timelib_sub_wall(timelib_time *old_time, timelib_rel_time *interval)
339 {
340 int bias = 1;
341 timelib_time *t = timelib_time_clone(old_time);
342
343 t->have_relative = 1;
344 t->sse_uptodate = 0;
345
346 if (interval->have_weekday_relative || interval->have_special_relative) {
347 memcpy(&t->relative, interval, sizeof(timelib_rel_time));
348
349 timelib_update_ts(t, NULL);
350 timelib_update_from_sse(t);
351 } else {
352 if (interval->invert) {
353 bias = -1;
354 }
355 memset(&t->relative, 0, sizeof(timelib_rel_time));
356 t->relative.y = 0 - (interval->y * bias);
357 t->relative.m = 0 - (interval->m * bias);
358 t->relative.d = 0 - (interval->d * bias);
359
360 if (t->relative.y || t->relative.m || t->relative.d) {
361 timelib_update_ts(t, NULL);
362 }
363
364 if (interval->us == 0) {
365 t->sse -= bias * timelib_hms_to_seconds(interval->h, interval->i, interval->s);
366 timelib_update_from_sse(t);
367 } else {
368 timelib_rel_time *temp_interval = timelib_rel_time_clone(interval);
369
370 do_range_limit(0, 1000000, 1000000, &temp_interval->us, &temp_interval->s);
371 t->sse -= bias * timelib_hms_to_seconds(temp_interval->h, temp_interval->i, temp_interval->s);
372 timelib_update_from_sse(t);
373 t->us -= temp_interval->us * bias;
374
375 timelib_do_normalize(t);
376 timelib_update_ts(t, NULL);
377
378 timelib_rel_time_dtor(temp_interval);
379 }
380 timelib_do_normalize(t);
381 }
382
383 if (t->zone_type == TIMELIB_ZONETYPE_ID) {
384 timelib_set_timezone(t, t->tz_info);
385 }
386 t->have_relative = 0;
387
388 return t;
389 }
390
