sysdeps/unix/sysv/linux/clock_getcpuclockid.c

   1 /* clock_getcpuclockid -- Get a clockid_t for process CPU time.  Linux version.
   2    Copyright (C) 2004, 2005, 2006 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <time.h>
  21 #include <unistd.h>
  22 #include <kernel-features.h>
  23 #include "kernel-posix-cpu-timers.h"
  24
  25 #ifndef HAS_CPUCLOCK
  26 # define HAS_CPUCLOCK 1
  27 #endif
  28
  29 int
  30 clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
  31 {
  32 #ifdef __NR_clock_getres
  33   /* The clockid_t value is a simple computation from the PID.
  34      But we do a clock_getres call to validate it.  */
  35
  36   const clockid_t pidclock = MAKE_PROCESS_CPUCLOCK (pid, CPUCLOCK_SCHED);
  37
  38 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  39   extern int __libc_missing_posix_cpu_timers attribute_hidden;
  40 #  if !(__ASSUME_POSIX_TIMERS > 0)
  41   extern int __libc_missing_posix_timers attribute_hidden;
  42   if (__libc_missing_posix_timers && !__libc_missing_posix_cpu_timers)
  43     __libc_missing_posix_cpu_timers = 1;
  44 #  endif
  45   if (!__libc_missing_posix_cpu_timers)
  46 # endif
  47     {
  48       INTERNAL_SYSCALL_DECL (err);
  49       int r = INTERNAL_SYSCALL (clock_getres, err, 2, pidclock, NULL);
  50       if (!INTERNAL_SYSCALL_ERROR_P (r, err))
  51         {
  52           *clock_id = pidclock;
  53           return 0;
  54         }
  55
  56 # if !(__ASSUME_POSIX_TIMERS > 0)
  57       if (INTERNAL_SYSCALL_ERRNO (r, err) == ENOSYS)
  58         {
  59           /* The kernel doesn't support these calls at all.  */
  60           __libc_missing_posix_timers = 1;
  61           __libc_missing_posix_cpu_timers = 1;
  62         }
  63       else
  64 # endif
  65         if (INTERNAL_SYSCALL_ERRNO (r, err) == EINVAL)
  66           {
  67 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
  68             if (pidclock == MAKE_PROCESS_CPUCLOCK (0, CPUCLOCK_SCHED)
  69                 || INTERNAL_SYSCALL_ERROR_P (INTERNAL_SYSCALL
  70                                              (clock_getres, err, 2,
  71                                               MAKE_PROCESS_CPUCLOCK
  72                                               (0, CPUCLOCK_SCHED), NULL),
  73                                              err))
  74               /* The kernel doesn't support these clocks at all.  */
  75               __libc_missing_posix_cpu_timers = 1;
  76             else
  77 # endif
  78               /* The clock_getres system call checked the PID for us.  */
  79               return ESRCH;
  80           }
  81         else
  82           return INTERNAL_SYSCALL_ERRNO (r, err);
  83     }
  84 #endif
  85
  86   /* We don't allow any process ID but our own.  */
  87   if (pid != 0 && pid != getpid ())
  88     return EPERM;
  89
  90 #ifdef CLOCK_PROCESS_CPUTIME_ID
  91   if (HAS_CPUCLOCK)
  92     {
  93       /* Store the number.  */
  94       *clock_id = CLOCK_PROCESS_CPUTIME_ID;
  95
  96       return 0;
  97     }
  98 #endif
  99
 100   /* We don't have a timer for that.  */
 101   return ENOENT;
 102 }