rt/timer_gettime.c

   1 /* Copyright (C) 2000-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <pthread.h>
  21 #include <time.h>
  22
  23 #include "posix-timer.h"
  24
  25
  26 /* Get current value of timer TIMERID and store it in VLAUE.  */
  27 int
  28 timer_gettime (timer_t timerid, struct itimerspec *value)
  29 {
  30   struct timer_node *timer;
  31   struct timespec now, expiry;
  32   int retval = -1, armed = 0, valid;
  33   clock_t clock = 0;
  34
  35   pthread_mutex_lock (&__timer_mutex);
  36
  37   timer = timer_id2ptr (timerid);
  38   valid = timer_valid (timer);
  39
  40   if (valid) {
  41     armed = timer->armed;
  42     expiry = timer->expirytime;
  43     clock = timer->clock;
  44     value->it_interval = timer->value.it_interval;
  45   }
  46
  47   pthread_mutex_unlock (&__timer_mutex);
  48
  49   if (valid)
  50     {
  51       if (armed)
  52         {
  53           __clock_gettime (clock, &now);
  54           if (timespec_compare (&now, &expiry) < 0)
  55             timespec_sub (&value->it_value, &expiry, &now);
  56           else
  57             {
  58               value->it_value.tv_sec = 0;
  59               value->it_value.tv_nsec = 0;
  60             }
  61         }
  62       else
  63         {
  64           value->it_value.tv_sec = 0;
  65           value->it_value.tv_nsec = 0;
  66         }
  67
  68       retval = 0;
  69     }
  70   else
  71     __set_errno (EINVAL);
  72
  73   return retval;
  74 }