Commit | Line | Data |
233e9d1c |
1 | /* A little program to test the limits of your system's time functions |
2 | * See Porting/README.y2038 for details |
3 | */ |
1b289682 |
4 | |
5 | #include <time.h> |
6 | #include <stdio.h> |
7 | #include <math.h> |
8 | |
9 | time_t Time_Zero = 0; |
10 | |
11 | /* Visual C++ 2008's difftime() can't do negative times */ |
12 | double my_difftime(time_t left, time_t right) { |
13 | double diff = (double)left - (double)right; |
14 | return diff; |
15 | } |
16 | |
17 | void check_date_max( struct tm * (*date_func)(const time_t *), char *func_name ) { |
18 | struct tm *date; |
19 | time_t time = 0; |
20 | time_t last_time = 0; |
21 | time_t time_change; |
22 | int i; |
23 | |
24 | for (i = 0; i <= 63; i++) { |
25 | date = (*date_func)(&time); |
26 | |
27 | /* date_func() broke or tm_year overflowed */ |
28 | if(date == NULL || date->tm_year < 69) |
29 | break; |
30 | |
31 | last_time = time; |
32 | time += time + 1; |
33 | |
34 | /* time_t overflowed */ |
35 | if( time < last_time ) |
36 | break; |
37 | } |
38 | |
39 | /* Binary search for the exact failure point */ |
40 | time = last_time; |
41 | time_change = last_time / 2; |
42 | |
43 | do { |
44 | time += time_change; |
45 | |
46 | date = (*date_func)(&time); |
47 | |
48 | /* date_func() broke or tm_year overflowed or time_t overflowed */ |
49 | if(date == NULL || date->tm_year < 69 || time < last_time) { |
50 | time = last_time; |
51 | time_change = time_change / 2; |
52 | } |
53 | else { |
54 | last_time = time; |
55 | } |
56 | } while(time_change > 0); |
57 | |
58 | printf("%20s max %.0f\n", func_name, my_difftime(last_time, Time_Zero)); |
59 | } |
60 | |
61 | |
62 | void check_date_min( struct tm * (*date_func)(const time_t *), char *func_name ) { |
63 | struct tm *date; |
64 | time_t time = -1; |
65 | time_t last_time = 0; |
66 | time_t time_change; |
67 | int i; |
68 | |
69 | for (i = 1; i <= 63; i++) { |
70 | date = (*date_func)(&time); |
71 | |
72 | /* date_func() broke or tm_year underflowed */ |
73 | if(date == NULL || date->tm_year > 70) |
74 | break; |
75 | |
76 | last_time = time; |
77 | time += time; |
78 | |
79 | /* time_t underflowed */ |
80 | if( time > last_time ) |
81 | break; |
82 | } |
83 | |
84 | /* Binary search for the exact failure point */ |
85 | time = last_time; |
86 | time_change = last_time / 2; |
87 | |
88 | do { |
89 | time += time_change; |
90 | |
91 | date = (*date_func)(&time); |
92 | |
93 | /* gmtime() broke or tm_year overflowed or time_t overflowed */ |
94 | if(date == NULL || date->tm_year > 70 || time > last_time) { |
95 | time = last_time; |
96 | time_change = time_change / 2; |
97 | } |
98 | else { |
99 | last_time = time; |
100 | } |
101 | } while(time_change < 0); |
102 | |
103 | printf("%20s min %.0f\n", func_name, my_difftime(last_time, Time_Zero)); |
104 | } |
105 | |
106 | |
107 | int main(void) { |
108 | check_date_max(gmtime, "gmtime"); |
109 | check_date_max(localtime, "localtime"); |
110 | check_date_min(gmtime, "gmtime"); |
111 | check_date_min(localtime, "localtime"); |
112 | |
113 | return 0; |
114 | } |