nptl/pthread_condattr_setclock.c

   1 /* Copyright (C) 2003, 2004, 2007, 2008 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <stdbool.h>
  23 #include <time.h>
  24 #include <sysdep.h>
  25 #include "pthreadP.h"
  26 #include <kernel-features.h>
  27
  28
  29 int
  30 pthread_condattr_setclock (attr, clock_id)
  31      pthread_condattr_t *attr;
  32      clockid_t clock_id;
  33 {
  34   /* Only a few clocks are allowed.  CLOCK_REALTIME is always allowed.
  35      CLOCK_MONOTONIC only if the kernel has the necessary support.  */
  36   if (clock_id == CLOCK_MONOTONIC)
  37     {
  38 #ifndef __ASSUME_POSIX_TIMERS
  39 # ifdef __NR_clock_getres
  40       /* Check whether the clock is available.  */
  41       static int avail;
  42
  43       if (avail == 0)
  44         {
  45           struct timespec ts;
  46
  47           INTERNAL_SYSCALL_DECL (err);
  48           int val;
  49           val = INTERNAL_SYSCALL (clock_getres, err, 2, CLOCK_MONOTONIC, &ts);
  50           avail = INTERNAL_SYSCALL_ERROR_P (val, err) ? -1 : 1;
  51         }
  52
  53       if (avail < 0)
  54 # endif
  55         /* Not available.  */
  56         return EINVAL;
  57 #endif
  58     }
  59   else if (clock_id != CLOCK_REALTIME)
  60     /* If more clocks are allowed some day the storing of the clock ID
  61        in the pthread_cond_t structure needs to be adjusted.  */
  62     return EINVAL;
  63
  64   /* Make sure the value fits in the bits we reserved.  */
  65   assert (clock_id < (1 << COND_NWAITERS_SHIFT));
  66
  67   int *valuep = &((struct pthread_condattr *) attr)->value;
  68
  69   *valuep = ((*valuep & ~(((1 << COND_NWAITERS_SHIFT) - 1) << 1))
  70              | (clock_id << 1));
  71
  72   return 0;
  73 }