include/babeltrace/compat/utc-internal.h

   1 #ifndef _BABELTRACE_UTC_H
   2 #define _BABELTRACE_UTC_H
   3
   4 /*
   5  * Copyright (C) 2011-2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE.
  24  */
  25
  26 #include <time.h>
  27
  28 /* If set, use GNU or BSD timegm(3) */
  29 #if defined(_BSD_SOURCE) || defined(_SVID_SOURCE)
  30
  31 static inline
  32 time_t bt_timegm(struct tm *tm)
  33 {
  34         return timegm(tm);
  35 }
  36
  37 #elif defined(__MINGW32__)
  38
  39 static inline
  40 time_t bt_timegm(struct tm *tm)
  41 {
  42         return _mkgmtime(tm);
  43 }
  44
  45 #else
  46
  47 #include <errno.h>
  48
  49 /*
  50  * This is a simple implementation of timegm() it just turns the "struct tm" into
  51  * a GMT time_t. It does not normalize any of the fields of the "struct tm", nor
  52  * does it set tm_wday or tm_yday.
  53  */
  54
  55 static inline
  56 int bt_leapyear(int year)
  57 {
  58     return ((year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0));
  59 }
  60
  61 static inline
  62 time_t bt_timegm(struct tm *tm)
  63 {
  64         int year, month, total_days;
  65
  66         int monthlen[2][12] = {
  67                 /* Days per month for a regular year */
  68                 { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
  69                 /* Days per month for a leap year */
  70                 { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
  71         };
  72
  73         if ((tm->tm_mon >= 12) ||
  74                         (tm->tm_mday >= 32) ||
  75                         (tm->tm_hour >= 24) ||
  76                         (tm->tm_min >= 60) ||
  77                         (tm->tm_sec >= 61)) {
  78                 errno = EOVERFLOW;
  79                 return (time_t) -1;
  80         }
  81
  82         /* Add 365 days for each year since 1970 */
  83         total_days = 365 * (tm->tm_year - 70);
  84
  85         /* Add one day for each leap year since 1970 */
  86         for (year = 70; year < tm->tm_year; year++) {
  87                 if (bt_leapyear(1900 + year)) {
  88                         total_days++;
  89                 }
  90         }
  91
  92         /* Add days for each remaining month */
  93         for (month = 0; month < tm->tm_mon; month++) {
  94                 total_days += monthlen[bt_leapyear(1900 + year)][month];
  95         }
  96
  97         /* Add remaining days */
  98         total_days += tm->tm_mday - 1;
  99
 100         return ((((total_days * 24) + tm->tm_hour) * 60 + tm->tm_min) * 60 + tm->tm_sec);
 101 }
 102
 103 #endif
 104
 105 #endif /* _BABELTRACE_UTC_H */