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-rw-r--r--win32/timegm.c133
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diff --git a/win32/timegm.c b/win32/timegm.c
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1/*
2 timegm from musl (https://www.musl-libc.org/).
3
4 MIT licensed:
5
6----------------------------------------------------------------------
7Copyright © 2005-2020 Rich Felker, et al.
8
9Permission is hereby granted, free of charge, to any person obtaining
10a copy of this software and associated documentation files (the
11"Software"), to deal in the Software without restriction, including
12without limitation the rights to use, copy, modify, merge, publish,
13distribute, sublicense, and/or sell copies of the Software, and to
14permit persons to whom the Software is furnished to do so, subject to
15the following conditions:
16
17The above copyright notice and this permission notice shall be
18included in all copies or substantial portions of the Software.
19
20THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
23IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
24CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
25TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
26SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
27----------------------------------------------------------------------
28*/
29#include "libbb.h"
30
31static long long __year_to_secs(long long year, int *is_leap)
32{
33 int cycles, centuries, leaps, rem;
34
35 if (year-2ULL <= 136) {
36 int y = year;
37 leaps = (y-68)>>2;
38 if (!((y-68)&3)) {
39 leaps--;
40 if (is_leap) *is_leap = 1;
41 } else if (is_leap) *is_leap = 0;
42 return 31536000*(y-70) + 86400*leaps;
43 }
44
45 cycles = (year-100) / 400;
46 rem = (year-100) % 400;
47 if (rem < 0) {
48 cycles--;
49 rem += 400;
50 }
51 if (!rem) {
52 *is_leap = 1;
53 centuries = 0;
54 leaps = 0;
55 } else {
56 if (rem >= 200) {
57 if (rem >= 300) centuries = 3, rem -= 300;
58 else centuries = 2, rem -= 200;
59 } else {
60 if (rem >= 100) centuries = 1, rem -= 100;
61 else centuries = 0;
62 }
63 if (!rem) {
64 *is_leap = 0;
65 leaps = 0;
66 } else {
67 leaps = rem / 4U;
68 rem %= 4U;
69 *is_leap = !rem;
70 }
71 }
72
73 leaps += 97*cycles + 24*centuries - *is_leap;
74
75 return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
76}
77
78static int __month_to_secs(int month, int is_leap)
79{
80 static const int secs_through_month[] = {
81 0, 31*86400, 59*86400, 90*86400,
82 120*86400, 151*86400, 181*86400, 212*86400,
83 243*86400, 273*86400, 304*86400, 334*86400 };
84 int t = secs_through_month[month];
85 if (is_leap && month >= 2) t+=86400;
86 return t;
87}
88
89static long long __tm_to_secs(const struct tm *tm)
90{
91 int is_leap;
92 long long t;
93 long long year = tm->tm_year;
94 int month = tm->tm_mon;
95 if (month >= 12 || month < 0) {
96 int adj = month / 12;
97 month %= 12;
98 if (month < 0) {
99 adj--;
100 month += 12;
101 }
102 year += adj;
103 }
104 t = __year_to_secs(year, &is_leap);
105 t += __month_to_secs(month, is_leap);
106 t += 86400LL * (tm->tm_mday-1);
107 t += 3600LL * tm->tm_hour;
108 t += 60LL * tm->tm_min;
109 t += tm->tm_sec;
110 return t;
111}
112
113/*
114 * Restricted version of timegm:
115 *
116 * it doesn't normalise its argument
117 * its return value is limited to the range Microsoft supports
118 */
119time_t timegm(struct tm *tm)
120{
121 long long t = __tm_to_secs(tm);
122 if (t < 0 ||
123#ifdef _USE_32BIT_TIME_T
124 t > INT_MAX /* 2038-01-19 03:14:07Z */
125#else
126 t > 32535215999 /* 3000-12-31 23:59:59Z */
127#endif
128 ) {
129 errno = EOVERFLOW;
130 return -1;
131 }
132 return t;
133}