sysdeps/posix/gettimeofday.c

   1 /* Copyright (C) 1991-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <time.h>
  20 #include <sys/time.h>
  21
  22 /* Get the current time of day and timezone information,
  23    putting it into *TV and *TZ.  If TZ is NULL, *TZ is not filled.
  24    Returns 0 on success, -1 on errors.  */
  25 int
  26 __gettimeofday (struct timeval *tv, struct timezone *tz)
  27 {
  28   if (tv == NULL)
  29     {
  30       __set_errno (EINVAL);
  31       return -1;
  32     }
  33
  34   tv->tv_sec = (long int) time ((time_t *) NULL);
  35   tv->tv_usec = 0L;
  36
  37   if (tz != NULL)
  38     {
  39       const time_t timer = tv->tv_sec;
  40       struct tm tm;
  41       const struct tm *tmp;
  42
  43       const long int save_timezone = __timezone;
  44       const long int save_daylight = __daylight;
  45       char *save_tzname[2];
  46       save_tzname[0] = __tzname[0];
  47       save_tzname[1] = __tzname[1];
  48
  49       tmp = localtime_r (&timer, &tm);
  50
  51       tz->tz_minuteswest = __timezone / 60;
  52       tz->tz_dsttime = __daylight;
  53
  54       __timezone = save_timezone;
  55       __daylight = save_daylight;
  56       __tzname[0] = save_tzname[0];
  57       __tzname[1] = save_tzname[1];
  58
  59       if (tmp == NULL)
  60         return -1;
  61     }
  62
  63   return 0;
  64 }
  65 libc_hidden_def (__gettimeofday)
  66 weak_alias (__gettimeofday, gettimeofday)
  67 libc_hidden_weak (gettimeofday)