nptl/pthread_condattr_setclock.c

   1 /* Copyright (C) 2003-2018 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
   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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <futex-internal.h>
  22 #include <time.h>
  23 #include <sysdep.h>
  24 #include "pthreadP.h"
  25
  26
  27 int
  28 pthread_condattr_setclock (pthread_condattr_t *attr, clockid_t clock_id)
  29 {
  30   /* Only a few clocks are allowed.  */
  31   if (clock_id != CLOCK_MONOTONIC && clock_id != CLOCK_REALTIME)
  32     /* If more clocks are allowed some day the storing of the clock ID
  33        in the pthread_cond_t structure needs to be adjusted.  */
  34     return EINVAL;
  35
  36   /* If we do not support waiting using CLOCK_MONOTONIC, return an error.  */
  37   if (clock_id == CLOCK_MONOTONIC
  38       && !futex_supports_exact_relative_timeouts())
  39     return ENOTSUP;
  40
  41   /* Make sure the value fits in the bits we reserved.  */
  42   assert (clock_id < (1 << COND_CLOCK_BITS));
  43
  44   int *valuep = &((struct pthread_condattr *) attr)->value;
  45
  46   *valuep = ((*valuep & ~(((1 << COND_CLOCK_BITS) - 1) << 1))
  47              | (clock_id << 1));
  48
  49   return 0;
  50 }