lib/settime.c

   1 /* settime -- set the system clock
   2
   3    Copyright (C) 2002, 2004-2007, 2009-2024 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #include <config.h>
  21
  22 #include "timespec.h"
  23
  24 #include <sys/time.h>
  25 #include <unistd.h>
  26
  27 #include <errno.h>
  28
  29 /* Set the system time.  */
  30
  31 int
  32 settime (struct timespec const *ts)
  33 {
  34 #if defined CLOCK_REALTIME && HAVE_CLOCK_SETTIME
  35   {
  36     int r = clock_settime (CLOCK_REALTIME, ts);
  37     if (r == 0 || errno == EPERM)
  38       return r;
  39   }
  40 #endif
  41
  42 #if HAVE_SETTIMEOFDAY
  43   {
  44     struct timeval tv = { .tv_sec = ts->tv_sec,
  45                           .tv_usec = ts->tv_nsec / 1000 };
  46     return settimeofday (&tv, 0);
  47   }
  48 #elif HAVE_STIME
  49   /* This fails to compile on OSF1 V5.1, due to stime requiring
  50      a 'long int*' and tv_sec is 'int'.  But that system does provide
  51      settimeofday.  */
  52   return stime (&ts->tv_sec);
  53 #else
  54   errno = ENOSYS;
  55   return -1;
  56 #endif
  57 }