timegm.c revision 178825 
1/*
2 * Copyright (c) 1997 Kungliga Tekniska H�gskolan
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#include "der_locl.h"
35
36RCSID("$Id: timegm.c 21366 2007-06-27 10:06:22Z lha $");
37
38static int
39is_leap(unsigned y)
40{
41    y += 1900;
42    return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
43}
44
45/*
46 * This is a simplifed version of timegm(3) that doesn't accept out of
47 * bound values that timegm(3) normally accepts but those are not
48 * valid in asn1 encodings.
49 */
50
51time_t
52_der_timegm (struct tm *tm)
53{
54  static const unsigned ndays[2][12] ={
55    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
56    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
57  time_t res = 0;
58  unsigned i;
59
60  if (tm->tm_year < 0)
61      return -1;
62  if (tm->tm_mon < 0 || tm->tm_mon > 11)
63      return -1;
64  if (tm->tm_mday < 1 || tm->tm_mday > ndays[is_leap(tm->tm_year)][tm->tm_mon])
65      return -1;
66  if (tm->tm_hour < 0 || tm->tm_hour > 23)
67      return -1;
68  if (tm->tm_min < 0 || tm->tm_min > 59)
69      return -1;
70  if (tm->tm_sec < 0 || tm->tm_sec > 59)
71      return -1;
72
73  for (i = 70; i < tm->tm_year; ++i)
74    res += is_leap(i) ? 366 : 365;
75
76  for (i = 0; i < tm->tm_mon; ++i)
77    res += ndays[is_leap(tm->tm_year)][i];
78  res += tm->tm_mday - 1;
79  res *= 24;
80  res += tm->tm_hour;
81  res *= 60;
82  res += tm->tm_min;
83  res *= 60;
84  res += tm->tm_sec;
85  return res;
86}
87