sysdeps/unix/sysv/linux/clock_getres.c

   1 /* Copyright (C) 2003 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <sysdep.h>
  20
  21 #include "kernel-features.h"
  22
  23
  24 #ifdef __ASSUME_POSIX_TIMERS
  25 /* This means the REALTIME and MONOTONIC clock are definitely
  26    supported in the kernel.  */
  27 # define SYSDEP_GETRES \
  28   case CLOCK_REALTIME:                                                        \
  29   case CLOCK_MONOTONIC:                                                       \
  30     retval = INLINE_SYSCALL (clock_getres, 2, clock_id, res);                 \
  31     break
  32 #elif defined __NR_clock_getres
  33 /* Is the syscall known to exist?  */
  34 extern int __libc_missing_posix_timers attribute_hidden;
  35
  36 /* The REALTIME and MONOTONIC clock might be available.  Try the
  37    syscall first.  */
  38 # define SYSDEP_GETRES \
  39   case CLOCK_REALTIME:                                                        \
  40   case CLOCK_MONOTONIC:                                                       \
  41     {                                                                         \
  42       int e = EINVAL;                                                         \
  43                                                                               \
  44       if (!__libc_missing_posix_timers)                                       \
  45         {                                                                     \
  46           INTERNAL_SYSCALL_DECL (err);                                        \
  47           int r = INTERNAL_SYSCALL (clock_getres, err, 2, clock_id, res);     \
  48           if (!INTERNAL_SYSCALL_ERROR_P (r, err))                             \
  49             {                                                                 \
  50               retval = 0;                                                     \
  51               break;                                                          \
  52             }                                                                 \
  53                                                                               \
  54           e = INTERNAL_SYSCALL_ERRNO (r, err);                                \
  55           if (e == ENOSYS)                                                    \
  56             {                                                                 \
  57               __libc_missing_posix_timers = 1;                                \
  58               e = EINVAL;                                                     \
  59             }                                                                 \
  60         }                                                                     \
  61                                                                               \
  62       /* Fallback code.  */                                                   \
  63       if (e == EINVAL && clock_id == CLOCK_REALTIME)                          \
  64         HANDLE_REALTIME;                                                      \
  65       else                                                                    \
  66         __set_errno (e);                                                      \
  67     }                                                                         \
  68     break
  69 #endif
  70
  71 #ifdef __NR_clock_getres
  72 /* We handled the REALTIME clock here.  */
  73 # define HANDLED_REALTIME       1
  74 #endif
  75
  76 #include <sysdeps/posix/clock_getres.c>