1 /*
2 * The MIT License (MIT)
3 *
4 * Copyright (c) 2015-2021 Derick Rethans
5 * Copyright (c) 2021 MongoDB
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25
26 #include "timelib.h"
27 #include "timelib_private.h"
28
timelib_unixtime2date(timelib_sll ts,timelib_sll * y,timelib_sll * m,timelib_sll * d)29 void timelib_unixtime2date(timelib_sll ts, timelib_sll *y, timelib_sll *m, timelib_sll *d)
30 {
31 timelib_sll days, era, t;
32 timelib_ull day_of_era, year_of_era, day_of_year, month_portion;
33
34 /* Calculate days since algorithm's epoch (0000-03-01) */
35 days = ts / SECS_PER_DAY + HINNANT_EPOCH_SHIFT;
36
37 /* Adjustment for a negative time portion */
38 t = ts % SECS_PER_DAY;
39 days += (t < 0) ? -1 : 0;
40
41 /* Calculate year, month, and day. Algorithm from:
42 * http://howardhinnant.github.io/date_algorithms.html#civil_from_days */
43 era = (days >= 0 ? days : days - DAYS_PER_ERA + 1) / DAYS_PER_ERA;
44 day_of_era = days - era * DAYS_PER_ERA;
45 year_of_era = (day_of_era - day_of_era / 1460 + day_of_era / 36524 - day_of_era / 146096) / DAYS_PER_YEAR;
46 *y = year_of_era + era * YEARS_PER_ERA;
47 day_of_year = day_of_era - (DAYS_PER_YEAR * year_of_era + year_of_era / 4 - year_of_era / 100);
48 month_portion = (5 * day_of_year + 2) / 153;
49 *d = day_of_year - (153 * month_portion + 2) / 5 + 1;
50 *m = month_portion + (month_portion < 10 ? 3 : -9);
51 *y += (*m <= 2);
52
53 TIMELIB_DEBUG(printf("A: ts=%lld, year=%lld, month=%lld, day=%lld,", ts, *y, *m, *d););
54 }
55
56 /* Converts a Unix timestamp value into broken down time, in GMT */
timelib_unixtime2gmt(timelib_time * tm,timelib_sll ts)57 void timelib_unixtime2gmt(timelib_time* tm, timelib_sll ts)
58 {
59 timelib_sll remainder;
60 timelib_sll hours, minutes, seconds;
61
62 timelib_unixtime2date(ts, &tm->y, &tm->m, &tm->d);
63 remainder = ts % SECS_PER_DAY;
64 remainder += (remainder < 0) * SECS_PER_DAY;
65
66 /* That was the date, now we do the time */
67 hours = remainder / 3600;
68 minutes = (remainder - hours * 3600) / 60;
69 seconds = remainder % 60;
70 TIMELIB_DEBUG(printf(" hour=%lld, minute=%lld, second=%lld\n", hours, minutes, seconds););
71
72 tm->h = hours;
73 tm->i = minutes;
74 tm->s = seconds;
75 tm->z = 0;
76 tm->dst = 0;
77 tm->sse = ts;
78 tm->sse_uptodate = 1;
79 tm->tim_uptodate = 1;
80 tm->is_localtime = 0;
81 }
82
timelib_update_from_sse(timelib_time * tm)83 void timelib_update_from_sse(timelib_time *tm)
84 {
85 timelib_sll sse;
86 int z = tm->z;
87 signed int dst = tm->dst;
88
89 sse = tm->sse;
90
91 switch (tm->zone_type) {
92 case TIMELIB_ZONETYPE_ABBR:
93 case TIMELIB_ZONETYPE_OFFSET: {
94 timelib_unixtime2gmt(tm, tm->sse + tm->z + (tm->dst * 3600));
95
96 goto cleanup;
97 }
98
99 case TIMELIB_ZONETYPE_ID: {
100 timelib_time_offset *gmt_offset;
101
102 gmt_offset = timelib_get_time_zone_info(tm->sse, tm->tz_info);
103 timelib_unixtime2gmt(tm, tm->sse + gmt_offset->offset);
104 timelib_time_offset_dtor(gmt_offset);
105
106 goto cleanup;
107 }
108
109 default:
110 timelib_unixtime2gmt(tm, tm->sse);
111 goto cleanup;
112 }
113 cleanup:
114 tm->sse = sse;
115 tm->is_localtime = 1;
116 tm->have_zone = 1;
117 tm->z = z;
118 tm->dst = dst;
119 }
120
timelib_unixtime2local(timelib_time * tm,timelib_sll ts)121 void timelib_unixtime2local(timelib_time *tm, timelib_sll ts)
122 {
123 timelib_time_offset *gmt_offset;
124 timelib_tzinfo *tz = tm->tz_info;
125
126 switch (tm->zone_type) {
127 case TIMELIB_ZONETYPE_ABBR:
128 case TIMELIB_ZONETYPE_OFFSET: {
129 int z = tm->z;
130 signed int dst = tm->dst;
131
132 timelib_unixtime2gmt(tm, ts + tm->z + (tm->dst * 3600));
133
134 tm->sse = ts;
135 tm->z = z;
136 tm->dst = dst;
137 break;
138 }
139
140 case TIMELIB_ZONETYPE_ID:
141 gmt_offset = timelib_get_time_zone_info(ts, tz);
142 timelib_unixtime2gmt(tm, ts + gmt_offset->offset);
143
144 /* we need to reset the sse here as unixtime2gmt modifies it */
145 tm->sse = ts;
146 tm->dst = gmt_offset->is_dst;
147 tm->z = gmt_offset->offset;
148 tm->tz_info = tz;
149
150 timelib_time_tz_abbr_update(tm, gmt_offset->abbr);
151 timelib_time_offset_dtor(gmt_offset);
152 break;
153
154 default:
155 tm->is_localtime = 0;
156 tm->have_zone = 0;
157 return;
158 }
159
160 tm->is_localtime = 1;
161 tm->have_zone = 1;
162 }
163
timelib_set_timezone_from_offset(timelib_time * t,timelib_sll utc_offset)164 void timelib_set_timezone_from_offset(timelib_time *t, timelib_sll utc_offset)
165 {
166 if (t->tz_abbr) {
167 timelib_free(t->tz_abbr);
168 }
169 t->tz_abbr = NULL;
170
171 t->z = utc_offset;
172 t->have_zone = 1;
173 t->zone_type = TIMELIB_ZONETYPE_OFFSET;
174 t->dst = 0;
175 t->tz_info = NULL;
176 }
177
timelib_set_timezone_from_abbr(timelib_time * t,timelib_abbr_info abbr_info)178 void timelib_set_timezone_from_abbr(timelib_time *t, timelib_abbr_info abbr_info)
179 {
180 if (t->tz_abbr) {
181 timelib_free(t->tz_abbr);
182 }
183 t->tz_abbr = timelib_strdup(abbr_info.abbr);
184
185 t->z = abbr_info.utc_offset;
186 t->have_zone = 1;
187 t->zone_type = TIMELIB_ZONETYPE_ABBR;
188 t->dst = abbr_info.dst;
189 t->tz_info = NULL;
190 }
191
timelib_set_timezone(timelib_time * t,timelib_tzinfo * tz)192 void timelib_set_timezone(timelib_time *t, timelib_tzinfo *tz)
193 {
194 timelib_time_offset *gmt_offset;
195
196 gmt_offset = timelib_get_time_zone_info(t->sse, tz);
197 t->z = gmt_offset->offset;
198 /*
199 if (t->dst != gmt_offset->is_dst) {
200 printf("ERROR (%d, %d)\n", t->dst, gmt_offset->is_dst);
201 exit(1);
202 }
203 */
204 t->dst = gmt_offset->is_dst;
205 t->tz_info = tz;
206 if (t->tz_abbr) {
207 timelib_free(t->tz_abbr);
208 }
209 t->tz_abbr = timelib_strdup(gmt_offset->abbr);
210 timelib_time_offset_dtor(gmt_offset);
211
212 t->have_zone = 1;
213 t->zone_type = TIMELIB_ZONETYPE_ID;
214 }
215
216 /* Converts the time stored in the struct to localtime if localtime = true,
217 * otherwise it converts it to gmttime. This is only done when necessary
218 * of course. */
timelib_apply_localtime(timelib_time * t,unsigned int localtime)219 int timelib_apply_localtime(timelib_time *t, unsigned int localtime)
220 {
221 if (localtime) {
222 /* Converting from GMT time to local time */
223 TIMELIB_DEBUG(printf("Converting from GMT time to local time\n"););
224
225 /* Check if TZ is set */
226 if (!t->tz_info) {
227 TIMELIB_DEBUG(printf("E: No timezone configured, can't switch to local time\n"););
228 return -1;
229 }
230
231 timelib_unixtime2local(t, t->sse);
232 } else {
233 /* Converting from local time to GMT time */
234 TIMELIB_DEBUG(printf("Converting from local time to GMT time\n"););
235
236 timelib_unixtime2gmt(t, t->sse);
237 }
238 return 0;
239 }
240
