1 /* $OpenBSD: ctime.c,v 1.6 2018/05/23 16:23:48 cheloha Exp $ */
2
3 /*
4 * Copyright (c) 1998 Michael Shalayeff
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <sys/time.h>
29 #include "stand.h"
30
31 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
32
33 char *
ctime(const time_t * clock)34 ctime(const time_t *clock)
35 {
36 static const char wdays[][4] = {
37 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
38 };
39 static const char months[][4] = {
40 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
41 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
42 };
43 static const u_int monthcnt[] = {
44 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
45 };
46 static char buf[64];
47 int ss, mm, hh, wday, month, year;
48 time_t tt = *clock;
49
50 ss = tt % 60;
51 tt /= 60; /* minutes */
52 mm = tt % 60;
53 tt /= 60; /* hours */
54 hh = tt % 24;
55 tt /= 24; /* days */
56 wday = (4 + tt) % 7; /* weekday, 'twas thursday when time started */
57
58 for (year = 1970; tt >= 365; year++)
59 tt -= isleap(year)? 366: 365;
60
61 tt++; /* days are 1-based */
62
63 for (month = 0; tt > monthcnt[month]; month++)
64 tt -= monthcnt[month];
65
66 if (month > 2 && isleap(year))
67 tt--;
68
69 snprintf(buf, sizeof buf, "%s %s%3d %02d:%02d:%02d %d\n",
70 ((wday < 0 || wday >= 7)? "???": wdays[wday]),
71 ((month < 0 || month >= 12)? "???": months[month]),
72 (int)tt, hh, mm, ss, year);
73 return buf;
74 }
75