sysdeps/unix/sysv/linux/clock_getres.c

   1 /* clock_getres -- Get the resolution of a POSIX clockid_t.  Linux version.
   2    Copyright (C) 2003,2004,2005,2006, 2008 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 <sysdep.h>
  21 #include <errno.h>
  22 #include <time.h>
  23 #include "kernel-posix-cpu-timers.h"
  24 #include <kernel-features.h>
  25
  26 #ifndef HAVE_CLOCK_GETRES_VSYSCALL
  27 # undef INTERNAL_VSYSCALL
  28 # define INTERNAL_VSYSCALL INTERNAL_SYSCALL
  29 # undef INLINE_VSYSCALL
  30 # define INLINE_VSYSCALL INLINE_SYSCALL
  31 #else
  32 # include <bits/libc-vdso.h>
  33 #endif
  34
  35 #define SYSCALL_GETRES \
  36   retval = INLINE_VSYSCALL (clock_getres, 2, clock_id, res); \
  37   break
  38
  39 #ifdef __ASSUME_POSIX_TIMERS
  40
  41 /* This means the REALTIME and MONOTONIC clock are definitely
  42    supported in the kernel.  */
  43 # define SYSDEP_GETRES                                                        \
  44   SYSDEP_GETRES_CPUTIME                                                       \
  45   case CLOCK_REALTIME:                                                        \
  46   case CLOCK_MONOTONIC:                                                       \
  47     SYSCALL_GETRES
  48
  49 # define __libc_missing_posix_timers 0
  50 #elif defined __NR_clock_getres
  51 /* Is the syscall known to exist?  */
  52 extern int __libc_missing_posix_timers attribute_hidden;
  53
  54 static inline int
  55 maybe_syscall_getres (clockid_t clock_id, struct timespec *res)
  56 {
  57   int e = EINVAL;
  58
  59   if (!__libc_missing_posix_timers)
  60     {
  61       INTERNAL_SYSCALL_DECL (err);
  62       int r = INTERNAL_VSYSCALL (clock_getres, err, 2, clock_id, res);
  63       if (!INTERNAL_SYSCALL_ERROR_P (r, err))
  64         return 0;
  65
  66       e = INTERNAL_SYSCALL_ERRNO (r, err);
  67       if (e == ENOSYS)
  68         {
  69           __libc_missing_posix_timers = 1;
  70           e = EINVAL;
  71         }
  72     }
  73
  74   return e;
  75 }
  76
  77 /* The REALTIME and MONOTONIC clock might be available.  Try the
  78    syscall first.  */
  79 # define SYSDEP_GETRES                                                        \
  80   SYSDEP_GETRES_CPUTIME                                                       \
  81   case CLOCK_REALTIME:                                                        \
  82   case CLOCK_MONOTONIC:                                                       \
  83     retval = maybe_syscall_getres (clock_id, res);                            \
  84     if (retval == 0)                                                          \
  85       break;                                                                  \
  86     /* Fallback code.  */                                                     \
  87     if (retval == EINVAL && clock_id == CLOCK_REALTIME)                       \
  88       retval = realtime_getres (res);                                         \
  89     else                                                                      \
  90       {                                                                       \
  91         __set_errno (retval);                                                 \
  92         retval = -1;                                                          \
  93       }                                                                       \
  94     break;
  95 #endif
  96
  97 #ifdef __NR_clock_getres
  98 /* We handled the REALTIME clock here.  */
  99 # define HANDLED_REALTIME       1
 100 # define HANDLED_CPUTIME        1
 101
 102 # if __ASSUME_POSIX_CPU_TIMERS > 0
 103
 104 #  define SYSDEP_GETRES_CPU SYSCALL_GETRES
 105 #  define SYSDEP_GETRES_CPUTIME /* Default catches them too.  */
 106
 107 # else
 108
 109 extern int __libc_missing_posix_cpu_timers attribute_hidden;
 110
 111 static int
 112 maybe_syscall_getres_cpu (clockid_t clock_id, struct timespec *res)
 113 {
 114   int e = EINVAL;
 115
 116   if (!__libc_missing_posix_cpu_timers)
 117     {
 118       INTERNAL_SYSCALL_DECL (err);
 119       int r = INTERNAL_VSYSCALL (clock_getres, err, 2, clock_id, res);
 120       if (!INTERNAL_SYSCALL_ERROR_P (r, err))
 121         return 0;
 122
 123       e = INTERNAL_SYSCALL_ERRNO (r, err);
 124 #  ifndef __ASSUME_POSIX_TIMERS
 125       if (e == ENOSYS)
 126         {
 127           __libc_missing_posix_timers = 1;
 128           __libc_missing_posix_cpu_timers = 1;
 129           e = EINVAL;
 130         }
 131       else
 132 #  endif
 133         {
 134           if (e == EINVAL)
 135             {
 136               /* Check whether the kernel supports CPU clocks at all.
 137                  If not, record it for the future.  */
 138               r = INTERNAL_VSYSCALL (clock_getres, err, 2,
 139                                     MAKE_PROCESS_CPUCLOCK (0, CPUCLOCK_SCHED),
 140                                     NULL);
 141               if (INTERNAL_SYSCALL_ERROR_P (r, err))
 142                 __libc_missing_posix_cpu_timers = 1;
 143             }
 144         }
 145     }
 146
 147   return e;
 148 }
 149
 150 #  define SYSDEP_GETRES_CPU                                                   \
 151   retval = maybe_syscall_getres_cpu (clock_id, res);                          \
 152   if (retval == 0)                                                            \
 153     break;                                                                    \
 154   if (retval != EINVAL || !__libc_missing_posix_cpu_timers)                   \
 155     {                                                                         \
 156       __set_errno (retval);                                                   \
 157       retval = -1;                                                            \
 158       break;                                                                  \
 159     }                                                                         \
 160   retval = -1 /* Otherwise continue on to the HP_TIMING version.  */;
 161
 162 static inline int
 163 maybe_syscall_getres_cputime (clockid_t clock_id, struct timespec *res)
 164 {
 165   return maybe_syscall_getres_cpu
 166     (clock_id == CLOCK_THREAD_CPUTIME_ID
 167      ? MAKE_THREAD_CPUCLOCK (0, CPUCLOCK_SCHED)
 168      : MAKE_PROCESS_CPUCLOCK (0, CPUCLOCK_SCHED),
 169      res);
 170 }
 171
 172 #  define SYSDEP_GETRES_CPUTIME                                               \
 173     case CLOCK_PROCESS_CPUTIME_ID:                                            \
 174     case CLOCK_THREAD_CPUTIME_ID:                                             \
 175       retval = maybe_syscall_getres_cputime (clock_id, res);                  \
 176       if (retval == 0)                                                        \
 177         break;                                                                \
 178       if (retval != EINVAL || !__libc_missing_posix_cpu_timers)               \
 179         {                                                                     \
 180           __set_errno (retval);                                               \
 181           retval = -1;                                                        \
 182           break;                                                              \
 183         }                                                                     \
 184       retval = hp_timing_getres (res);                                        \
 185       break;
 186 #  if !HP_TIMING_AVAIL
 187 #   define hp_timing_getres(res) (__set_errno (EINVAL), -1)
 188 #  endif
 189
 190 # endif
 191 #endif
 192
 193 #include <sysdeps/posix/clock_getres.c>