1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
|
#define _REENTRANT_SOURCE
#include <time.h>
/*
* BUG: Doesn't do leap years in full glory,
* or calendar changes. In 2038 the sign bit
* will be needed in time_t, but we say it
* can't be represented.
*/
static int
dysize(int y)
{
y += 1900; /* arg is a tm_year, number of years since 1900 */
if((y%4) == 0 && ((y%100) !=0 || (y%400) == 0))
return 366;
return 365;
}
static int
dmsize(int m, int y)
{
static char sizes[12] =
{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
if(m == 1)
return (dysize(y)==366)? 29 : 28;
else
return sizes[m];
}
/* Reduce *v to [0, mult), adding 1 to *next for every mult
* subtracted from *v, and return 1 if reduction worked (no overflow)
*/
static int
reduce(int *v, int *next, int mult)
{
int oldnext;
while(*v < 0){
*v += mult;
oldnext = *next;
--*next;
if(!(*next < oldnext))
return 0;
}
while(*v >= mult){
*v -= mult;
oldnext = *next;
++*next;
if(!(*next > oldnext))
return 0;
}
return 1;
}
static int
jan1(int yr)
{
int y, d;
y = yr+1900;
d = (4+y+(y+3)/4-(y-1701)/100+(y-1601)/400+3)%7;
return d;
}
static time_t
tm2sec(struct tm *t)
{
time_t a;
int i;
a = t->tm_sec;
a += 60 * t->tm_min;
a += 3600 * t->tm_hour;
a += 86400L * t->tm_yday;
if(t->tm_year < 70){
for(i=t->tm_year; i<70; i++)
if((a -= dysize(i)*86400L) < 0)
return -1;
}else if(t->tm_year > 70){
for(i=70; i<t->tm_year; i++)
if((a += dysize(i)*86400L) < 0)
return -1;
}
return a;
}
time_t
mktime(struct tm *t)
{
int i;
time_t a, b;
struct tm tt;
if(!(reduce(&t->tm_sec, &t->tm_min, 60) &&
reduce(&t->tm_min, &t->tm_hour, 60) &&
reduce(&t->tm_hour, &t->tm_mday, 24) &&
reduce(&t->tm_mon, &t->tm_year, 12)))
return -1;
while(t->tm_mday < 1){
if(--t->tm_mon == -1){
t->tm_mon = 11;
t->tm_year--;
}
t->tm_mday += dmsize(t->tm_mon, t->tm_year);
}
while(t->tm_mday > dmsize(t->tm_mon, t->tm_year)){
t->tm_mday -= dmsize(t->tm_mon, t->tm_year);
if(++t->tm_mon == 12){
t->tm_mon = 0;
t->tm_year++;
}
}
t->tm_yday = t->tm_mday-1;
for(i=0; i<t->tm_mon; i++)
t->tm_yday += dmsize(i, t->tm_year);
t->tm_wday = (jan1(t->tm_year)+t->tm_yday)%7;
if((a = tm2sec(t)) != -1){
b = a;
localtime_r(&a, &tt);
a += (b - tm2sec(&tt));
if(t->tm_isdst < 0){
localtime_r(&a, &tt);
a += (b - tm2sec(&tt));
}
else if(!t->tm_isdst && tt.tm_isdst)
a += 3600;
else if(t->tm_isdst && !tt.tm_isdst)
a -= 3600;
}
return a;
}
|
