kernel/time/time_test.c

   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  */
   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  */
  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  */
  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  */
  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");