lib/roken/timegm.c

   1 /*
   2  * Copyright (c) 1997, 2006 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 <config.h>
  35
  36 #include "roken.h"
  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 /*
  46  * XXX This is a simplifed version of timegm, it needs to support out of
  47  * bounds values.
  48  */
  49
  50 time_t
  51 rk_timegm (struct tm *tm)
  52 {
  53   static const unsigned ndays[2][12] ={
  54     {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
  55     {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
  56   time_t res = 0;
  57   unsigned i;
  58
  59   if (tm->tm_year < 0)
  60       return -1;
  61   if (tm->tm_mon < 0 || tm->tm_mon > 11)
  62       return -1;
  63   if (tm->tm_mday < 1 || tm->tm_mday > ndays[is_leap(tm->tm_year)][tm->tm_mon])
  64       return -1;
  65   if (tm->tm_hour < 0 || tm->tm_hour > 23)
  66       return -1;
  67   if (tm->tm_min < 0 || tm->tm_min > 59)
  68       return -1;
  69   if (tm->tm_sec < 0 || tm->tm_sec > 59)
  70       return -1;
  71
  72   for (i = 70; i < tm->tm_year; ++i)
  73     res += is_leap(i) ? 366 : 365;
  74
  75   for (i = 0; i < tm->tm_mon; ++i)
  76     res += ndays[is_leap(tm->tm_year)][i];
  77   res += tm->tm_mday - 1;
  78   res *= 24;
  79   res += tm->tm_hour;
  80   res *= 60;
  81   res += tm->tm_min;
  82   res *= 60;
  83   res += tm->tm_sec;
  84   return res;
  85 }