/
date.c
79 lines (69 loc) · 2.4 KB
/
date.c
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
/* Copyright (c) 2017, Piotr Durlej
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <time.h>
#include <err.h>
#define dd2int(s) (((s)[0] - '0') * 10 + (s)[1] - '0')
#define dddd2int(s) (dd2int(s) * 100 + dd2int((s) + 2))
int main(int argc, char **argv)
{
time_t t = time(NULL);
char *s = argv[1];
struct tm *tm;
int l;
if (argc == 2 && !strcmp(argv[1], "--help"))
{
printf("\nUsage: date [MMDDhhmmss[CCYY]]\n\n"
"Show current time and date.\n"
"Set current time and date MMDDhhmmssCCYY.\n\n");
return 0;
}
if (argc > 2)
errx(255, "wrong number of arguments");
if (argc == 2)
{
l = strlen(s);
if (l != 10 && l != 14)
errx(255, "invalid date string");
if (strspn(s, "0123456789") != l)
errx(255, "invalid date string");
tm = localtime(&t);
tm->tm_mon = dd2int(s)-1;
tm->tm_mday = dd2int(s + 2);
tm->tm_hour = dd2int(s + 4);
tm->tm_min = dd2int(s + 6);
tm->tm_sec = dd2int(s + 8);
if (l > 10)
tm->tm_year = dddd2int(s + 10) - 1900;
t = mktime(tm);
}
printf("%s", ctime(&t));
if (argc == 2 && stime(&t))
err(errno, "stime");
return 0;
}