Move to kernel style SPDX license identifiers
[babeltrace.git] / src / compat / utc.h
1 /*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright (C) 2011-2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
5 */
6
7 #ifndef _BABELTRACE_UTC_H
8 #define _BABELTRACE_UTC_H
9
10 #include <time.h>
11
12 /* If set, use GNU or BSD timegm(3) */
13 #if defined(_BSD_SOURCE) || defined(_SVID_SOURCE)
14
15 static inline
16 time_t bt_timegm(struct tm *tm)
17 {
18 return timegm(tm);
19 }
20
21 #elif defined(__MINGW32__)
22
23 static inline
24 time_t bt_timegm(struct tm *tm)
25 {
26 return _mkgmtime(tm);
27 }
28
29 #else
30
31 #include <errno.h>
32
33 /*
34 * This is a simple implementation of timegm() it just turns the "struct tm" into
35 * a GMT time_t. It does not normalize any of the fields of the "struct tm", nor
36 * does it set tm_wday or tm_yday.
37 */
38
39 static inline
40 int bt_leapyear(int year)
41 {
42 return ((year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0));
43 }
44
45 static inline
46 time_t bt_timegm(struct tm *tm)
47 {
48 int year, month, total_days;
49
50 int monthlen[2][12] = {
51 /* Days per month for a regular year */
52 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
53 /* Days per month for a leap year */
54 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
55 };
56
57 if ((tm->tm_mon >= 12) ||
58 (tm->tm_mday >= 32) ||
59 (tm->tm_hour >= 24) ||
60 (tm->tm_min >= 60) ||
61 (tm->tm_sec >= 61)) {
62 errno = EOVERFLOW;
63 return (time_t) -1;
64 }
65
66 /* Add 365 days for each year since 1970 */
67 total_days = 365 * (tm->tm_year - 70);
68
69 /* Add one day for each leap year since 1970 */
70 for (year = 70; year < tm->tm_year; year++) {
71 if (bt_leapyear(1900 + year)) {
72 total_days++;
73 }
74 }
75
76 /* Add days for each remaining month */
77 for (month = 0; month < tm->tm_mon; month++) {
78 total_days += monthlen[bt_leapyear(1900 + year)][month];
79 }
80
81 /* Add remaining days */
82 total_days += tm->tm_mday - 1;
83
84 return ((((total_days * 24) + tm->tm_hour) * 60 + tm->tm_min) * 60 + tm->tm_sec);
85 }
86
87 #endif
88
89 #endif /* _BABELTRACE_UTC_H */
This page took 0.041502 seconds and 4 git commands to generate.