lib/asn1/timegm.c

   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 #include "der_locl.h"
  35
  36 RCSID("$Id$");
  37
  38 static int
  39 is_leap(unsigned y)
  40 {
  41     y += 1900;
  42     return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
  43 }
  44
  45 static const unsigned ndays[2][12] ={
  46     {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
  47     {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
  48
  49 /*
  50  * This is a simplifed version of timegm(3) that doesn't accept out of
  51  * bound values that timegm(3) normally accepts but those are not
  52  * valid in asn1 encodings.
  53  */
  54
  55 time_t
  56 _der_timegm (struct tm *tm)
  57 {
  58   time_t res = 0;
  59   unsigned i;
  60
  61   if (tm->tm_year < 0)
  62       return -1;
  63   if (tm->tm_mon < 0 || tm->tm_mon > 11)
  64       return -1;
  65   if (tm->tm_mday < 1 || tm->tm_mday > ndays[is_leap(tm->tm_year)][tm->tm_mon])
  66       return -1;
  67   if (tm->tm_hour < 0 || tm->tm_hour > 23)
  68       return -1;
  69   if (tm->tm_min < 0 || tm->tm_min > 59)
  70       return -1;
  71   if (tm->tm_sec < 0 || tm->tm_sec > 59)
  72       return -1;
  73
  74   for (i = 70; i < tm->tm_year; ++i)
  75     res += is_leap(i) ? 366 : 365;
  76
  77   for (i = 0; i < tm->tm_mon; ++i)
  78     res += ndays[is_leap(tm->tm_year)][i];
  79   res += tm->tm_mday - 1;
  80   res *= 24;
  81   res += tm->tm_hour;
  82   res *= 60;
  83   res += tm->tm_min;
  84   res *= 60;
  85   res += tm->tm_sec;
  86   return res;
  87 }
  88
  89 struct tm *
  90 _der_gmtime(time_t t, struct tm *tm)
  91 {
  92     time_t secday = t % (3600 * 24);
  93     time_t days = t / (3600 * 24);
  94
  95     memset(tm, 0, sizeof(*tm));
  96
  97     tm->tm_sec = secday % 60;
  98     tm->tm_min = (secday % 3600) / 60;
  99     tm->tm_hour = secday / 3600;
 100
 101     /*
 102      * Refuse to calculate time ~ 2000 years into the future, this is
 103      * not possible for systems where time_t is a int32_t, however,
 104      * when time_t is a int64_t, that can happen.
 105      */
 106     if (days > 356000)
 107         return NULL;
 108
 109     tm->tm_year = 70;
 110     while(1) {
 111         unsigned dayinyear = (is_leap(tm->tm_year) ? 366 : 365);
 112         if (days < dayinyear)
 113             break;
 114         tm->tm_year += 1;
 115         days -= dayinyear;
 116     }
 117     tm->tm_mon = 0;
 118
 119     while (1) {
 120         unsigned daysinmonth = ndays[is_leap(tm->tm_year)][tm->tm_mon];
 121         if (days < daysinmonth)
 122             break;
 123         days -= daysinmonth;
 124         tm->tm_mon++;
 125     }
 126     tm->tm_mday = days + 1;
 127
 128     return tm;
 129 }