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