xref: /freebsd/crypto/openssh/openbsd-compat/bsd-timegm.c (revision 2e3f49888ec8851bafb22011533217487764fdb0)
1 /*
2  * Copyright (c) 1997 Kungliga Tekniska Högskolan
3  * (Royal Institute of Technology, Stockholm, Sweden).
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  *
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * 3. Neither the name of the Institute nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 /*
35   adapted for Samba4 by Andrew Tridgell
36 */
37 
38 #include "includes.h"
39 
40 #include <time.h>
41 
42 #ifndef HAVE_TIMEGM
43 
44 static int is_leap(unsigned y)
45 {
46 	y += 1900;
47 	return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
48 }
49 
50 time_t timegm(struct tm *tm)
51 {
52 	static const unsigned ndays[2][12] ={
53 		{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
54 		{31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
55 	time_t res = 0;
56 	unsigned i;
57 
58 	if (tm->tm_mon > 12 ||
59 	    tm->tm_mon < 0 ||
60 	    tm->tm_mday > 31 ||
61 	    tm->tm_min > 60 ||
62 	    tm->tm_sec > 60 ||
63 	    tm->tm_hour > 24) {
64 		/* invalid tm structure */
65 		return 0;
66 	}
67 
68 	for (i = 70; i < tm->tm_year; ++i)
69 		res += is_leap(i) ? 366 : 365;
70 
71 	for (i = 0; i < tm->tm_mon; ++i)
72 		res += ndays[is_leap(tm->tm_year)][i];
73 	res += tm->tm_mday - 1;
74 	res *= 24;
75 	res += tm->tm_hour;
76 	res *= 60;
77 	res += tm->tm_min;
78 	res *= 60;
79 	res += tm->tm_sec;
80 	return res;
81 }
82 #endif /* HAVE_TIMEGM */
83