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
timelib_diff(timelib_time * one,timelib_time * two)29 timelib_rel_time *timelib_diff(timelib_time *one, timelib_time *two)
30 {
31 timelib_rel_time *rt;
32 timelib_time *swp;
33 timelib_sll dst_corr = 0 ,dst_h_corr = 0, dst_m_corr = 0;
34 timelib_time one_backup, two_backup;
35
36 rt = timelib_rel_time_ctor();
37 rt->invert = 0;
38 if (
39 (one->sse > two->sse) ||
40 (one->sse == two->sse && one->us > two->us)
41 ) {
42 swp = two;
43 two = one;
44 one = swp;
45 rt->invert = 1;
46 }
47
48 /* Calculate correction for DST change over, but only if the TZ type is ID
49 * and it's the same */
50 if (one->zone_type == 3 && two->zone_type == 3
51 && (strcmp(one->tz_info->name, two->tz_info->name) == 0)
52 && (one->z != two->z))
53 {
54 dst_corr = two->z - one->z;
55 dst_h_corr = dst_corr / 3600;
56 dst_m_corr = (dst_corr % 3600) / 60;
57 }
58
59 /* Save old TZ info */
60 memcpy(&one_backup, one, sizeof(one_backup));
61 memcpy(&two_backup, two, sizeof(two_backup));
62
63 timelib_apply_localtime(one, 0);
64 timelib_apply_localtime(two, 0);
65
66 rt->y = two->y - one->y;
67 rt->m = two->m - one->m;
68 rt->d = two->d - one->d;
69 rt->h = two->h - one->h;
70 rt->i = two->i - one->i;
71 rt->s = two->s - one->s;
72 rt->us = two->us - one->us;
73 if (one_backup.dst == 0 && two_backup.dst == 1 && two->sse >= one->sse + 86400 - dst_corr) {
74 rt->h += dst_h_corr;
75 rt->i += dst_m_corr;
76 }
77
78 rt->days = fabs(floor((one->sse - two->sse - (dst_h_corr * 3600) - (dst_m_corr * 60)) / 86400));
79
80 timelib_do_rel_normalize(rt->invert ? one : two, rt);
81
82 /* We need to do this after normalisation otherwise we can't get "24H" */
83 if (one_backup.dst == 1 && two_backup.dst == 0 && two->sse >= one->sse + 86400) {
84 if (two->sse < one->sse + 86400 - dst_corr) {
85 rt->d--;
86 rt->h = 24;
87 } else {
88 rt->h += dst_h_corr;
89 rt->i += dst_m_corr;
90 }
91 }
92
93 /* Restore old TZ info */
94 memcpy(one, &one_backup, sizeof(one_backup));
95 memcpy(two, &two_backup, sizeof(two_backup));
96
97 return rt;
98 }
99
timelib_add(timelib_time * old_time,timelib_rel_time * interval)100 timelib_time *timelib_add(timelib_time *old_time, timelib_rel_time *interval)
101 {
102 int bias = 1;
103 timelib_time *t = timelib_time_clone(old_time);
104
105 if (interval->have_weekday_relative || interval->have_special_relative) {
106 memcpy(&t->relative, interval, sizeof(timelib_rel_time));
107 } else {
108 if (interval->invert) {
109 bias = -1;
110 }
111 memset(&t->relative, 0, sizeof(timelib_rel_time));
112 t->relative.y = interval->y * bias;
113 t->relative.m = interval->m * bias;
114 t->relative.d = interval->d * bias;
115 t->relative.h = interval->h * bias;
116 t->relative.i = interval->i * bias;
117 t->relative.s = interval->s * bias;
118 t->relative.us = interval->us * bias;
119 }
120 t->have_relative = 1;
121 t->sse_uptodate = 0;
122
123 timelib_update_ts(t, NULL);
124
125 // printf("%lld %lld %d\n", old_time->dst, t->dst, (t->sse - old_time->sse));
126 /* Adjust for backwards DST changeover */
127 if (old_time->dst == 1 && t->dst == 0 && !interval->y && !interval->m && !interval->d) {
128 t->sse -= old_time->z;
129 t->sse += t->z;
130 }
131
132 timelib_update_from_sse(t);
133 t->have_relative = 0;
134
135 return t;
136 }
137
timelib_sub(timelib_time * old_time,timelib_rel_time * interval)138 timelib_time *timelib_sub(timelib_time *old_time, timelib_rel_time *interval)
139 {
140 int bias = 1;
141 timelib_time *t = timelib_time_clone(old_time);
142
143 if (interval->invert) {
144 bias = -1;
145 }
146
147 memset(&t->relative, 0, sizeof(timelib_rel_time));
148 t->relative.y = 0 - (interval->y * bias);
149 t->relative.m = 0 - (interval->m * bias);
150 t->relative.d = 0 - (interval->d * bias);
151 t->relative.h = 0 - (interval->h * bias);
152 t->relative.i = 0 - (interval->i * bias);
153 t->relative.s = 0 - (interval->s * bias);
154 t->relative.us = 0 - (interval->us * bias);
155 t->have_relative = 1;
156 t->sse_uptodate = 0;
157
158 timelib_update_ts(t, NULL);
159
160 /* Adjust for backwards DST changeover */
161 if (old_time->dst == 1 && t->dst == 0 && !interval->y && !interval->m && !interval->d) {
162 t->sse -= old_time->z;
163 t->sse += t->z;
164 }
165 /* Adjust for forwards DST changeover */
166 if (old_time->dst == 0 && t->dst == 1 && !interval->y && !interval->m && !interval->d ) {
167 t->sse -= old_time->z;
168 t->sse += t->z;
169 }
170
171 timelib_update_from_sse(t);
172
173 t->have_relative = 0;
174
175 return t;
176 }
177
