time/timegm.c

   1 /* Convert UTC calendar time to simple time.  Like mktime but assumes UTC.
   2
   3    Copyright (C) 1994-2023 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _LIBC
  21 # include <libc-config.h>
  22 #endif
  23
  24 #include <time.h>
  25 #include <errno.h>
  26
  27 #include "mktime-internal.h"
  28
  29 __time64_t
  30 __timegm64 (struct tm *tmp)
  31 {
  32   static mktime_offset_t gmtime_offset;
  33   tmp->tm_isdst = 0;
  34   return __mktime_internal (tmp, __gmtime64_r, &gmtime_offset);
  35 }
  36
  37 #if defined _LIBC && __TIMESIZE != 64
  38
  39 libc_hidden_def (__timegm64)
  40
  41 time_t
  42 timegm (struct tm *tmp)
  43 {
  44   struct tm tm = *tmp;
  45   __time64_t t = __timegm64 (&tm);
  46   if (in_time_t_range (t))
  47     {
  48       *tmp = tm;
  49       return t;
  50     }
  51   else
  52     {
  53       __set_errno (EOVERFLOW);
  54       return -1;
  55     }
  56 }
  57
  58 #endif