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1 // SPDX-License-Identifier: LGPL-2.1+
2 
3 #include <kunit/test.h>
4 #include <linux/time.h>
5 
6 /*
7  * Traditional implementation of leap year evaluation.
8  */
is_leap(long year)9 static bool is_leap(long year)
10 {
11 	return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
12 }
13 
14 /*
15  * Gets the last day of a month.
16  */
last_day_of_month(long year,int month)17 static int last_day_of_month(long year, int month)
18 {
19 	if (month == 2)
20 		return 28 + is_leap(year);
21 	if (month == 4 || month == 6 || month == 9 || month == 11)
22 		return 30;
23 	return 31;
24 }
25 
26 /*
27  * Advances a date by one day.
28  */
advance_date(long * year,int * month,int * mday,int * yday)29 static void advance_date(long *year, int *month, int *mday, int *yday)
30 {
31 	if (*mday != last_day_of_month(*year, *month)) {
32 		++*mday;
33 		++*yday;
34 		return;
35 	}
36 
37 	*mday = 1;
38 	if (*month != 12) {
39 		++*month;
40 		++*yday;
41 		return;
42 	}
43 
44 	*month = 1;
45 	*yday  = 0;
46 	++*year;
47 }
48 
49 /*
50  * Checks every day in a 160000 years interval centered at 1970-01-01
51  * against the expected result.
52  */
time64_to_tm_test_date_range(struct kunit * test)53 static void time64_to_tm_test_date_range(struct kunit *test)
54 {
55 	/*
56 	 * 80000 years	= (80000 / 400) * 400 years
57 	 *		= (80000 / 400) * 146097 days
58 	 *		= (80000 / 400) * 146097 * 86400 seconds
59 	 */
60 	time64_t total_secs = ((time64_t) 80000) / 400 * 146097 * 86400;
61 	long year = 1970 - 80000;
62 	int month = 1;
63 	int mdday = 1;
64 	int yday = 0;
65 
66 	struct tm result;
67 	time64_t secs;
68 	s64 days;
69 
70 	for (secs = -total_secs; secs <= total_secs; secs += 86400) {
71 
72 		time64_to_tm(secs, 0, &result);
73 
74 		days = div_s64(secs, 86400);
75 
76 		#define FAIL_MSG "%05ld/%02d/%02d (%2d) : %ld", \
77 			year, month, mdday, yday, days
78 
79 		KUNIT_ASSERT_EQ_MSG(test, year - 1900, result.tm_year, FAIL_MSG);
80 		KUNIT_ASSERT_EQ_MSG(test, month - 1, result.tm_mon, FAIL_MSG);
81 		KUNIT_ASSERT_EQ_MSG(test, mdday, result.tm_mday, FAIL_MSG);
82 		KUNIT_ASSERT_EQ_MSG(test, yday, result.tm_yday, FAIL_MSG);
83 
84 		advance_date(&year, &month, &mdday, &yday);
85 	}
86 }
87 
88 static struct kunit_case time_test_cases[] = {
89 	KUNIT_CASE(time64_to_tm_test_date_range),
90 	{}
91 };
92 
93 static struct kunit_suite time_test_suite = {
94 	.name = "time_test_cases",
95 	.test_cases = time_test_cases,
96 };
97 
98 kunit_test_suite(time_test_suite);
99 MODULE_LICENSE("GPL");
100