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
133
134
135
136
137
138
139
140
141
|
#include <stdlib.h>
#include <sys/types.h>
#include <fcntl.h>
#include <time.h>
#include <ctype.h>
#include <string.h>
#include <unistd.h>
#define TZFILE "/etc/TZ"
static char TZ[128];
static char std[32] = "GMT0";
static char dst[32];
char *tzname[2] = {
std, dst
};
time_t tzoffset, tzdstoffset;
int tzdst = 0;
static int
offset(char *env, time_t *off)
{
int n, sign;
size_t len, retlen;
retlen = 0;
sign = 1;
/*
* strictly, no sign is allowed in the 'time' part of the
* dst start/stop rules, but who cares?
*/
if (*env == '-' || *env == '+') {
if (*env++ == '-')
sign = -1;
retlen++;
}
if ((len = strspn(env, ":0123456789")) == 0)
return 0;
retlen += len;
for (*off = 0; len && isdigit(*env); len--) /* hours */
*off = *off*10 + (*env++ - '0')*60*60;
if (len) {
if (*env++ != ':')
return 0;
len--;
}
for (n = 0; len && isdigit(*env); len--) /* minutes */
n = n*10 + (*env++ - '0')*60;
*off += n;
if (len) {
if (*env++ != ':')
return 0;
len--;
}
for (n = 0; len && isdigit(*env); len--) /* seconds */
n = n*10 + (*env++ - '0');
*off = (*off + n)*sign;
return retlen;
}
/*
* TZ=stdoffset[dst[offset][,start[/time],end[/time]]]
*/
void
tzset(void)
{
char *env, *p, envbuf[128];
int fd, i;
size_t len, retlen;
time_t off;
/*
* get the TZ environment variable and check for validity.
* the implementation-defined manner for dealing with the
* leading ':' format is to reject it.
* if it's ok, stash a copy away for quick comparison next time.
*/
if ((env = getenv("TZ")) == 0) {
if ((fd = open(TZFILE, O_RDONLY)) == -1)
return;
if (read(fd, envbuf, sizeof(envbuf)-1) == -1) {
close(fd);
return;
}
close(fd);
for (i = 0; i < sizeof(envbuf); i++) {
if (envbuf[i] != '\n')
continue;
envbuf[i] = '\0';
break;
}
env = envbuf;
}
if (strcmp(env, TZ) == 0)
return;
if (*env == 0 || *env == ':')
return;
strncpy(TZ, env, sizeof(TZ)-1);
TZ[sizeof(TZ)-1] = 0;
/*
* get the 'std' string.
* before committing, check there is a valid offset.
*/
if ((len = strcspn(env, ":0123456789,-+")) == 0)
return;
if ((retlen = offset(env+len, &off)) == 0)
return;
for (p = std, i = len+retlen; i; i--)
*p++ = *env++;
*p = 0;
tzoffset = -off;
/*
* get the 'dst' string (if any).
*/
if (*env == 0 || (len = strcspn(env, ":0123456789,-+")) == 0)
return;
for (p = dst; len; len--)
*p++ = *env++;
*p = 0;
/*
* optional dst offset.
* default is one hour.
*/
tzdst = 1;
if (retlen = offset(env+len, &off)) {
tzdstoffset = -off;
env += retlen;
}
else
tzdstoffset = tzoffset + 60*60;
/*
* optional rule(s) for start/end of dst.
*/
if (*env == 0 || *env != ',' || *(env+1) == 0)
return;
env++;
/*
* we could go on...
* but why bother?
*/
}
|
