sysdeps/unix/sysv/linux/clock_getcpuclockid.c

   1 /* clock_getcpuclockid -- Get a clockid_t for process CPU time.  Linux version.
   2    Copyright (C) 2004-2014 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-posix-cpu-timers.h"
  23
  24 int
  25 __clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
  26 {
  27   /* The clockid_t value is a simple computation from the PID.
  28      But we do a clock_getres call to validate it.  */
  29
  30   const clockid_t pidclock = MAKE_PROCESS_CPUCLOCK (pid, CPUCLOCK_SCHED);
  31
  32   INTERNAL_SYSCALL_DECL (err);
  33   int r = INTERNAL_SYSCALL (clock_getres, err, 2, pidclock, NULL);
  34   if (!INTERNAL_SYSCALL_ERROR_P (r, err))
  35     {
  36       *clock_id = pidclock;
  37       return 0;
  38     }
  39
  40   if (INTERNAL_SYSCALL_ERRNO (r, err) == EINVAL)
  41     {
  42       /* The clock_getres system call checked the PID for us.  */
  43       return ESRCH;
  44     }
  45   else
  46     return INTERNAL_SYSCALL_ERRNO (r, err);
  47 }
  48 weak_alias (__clock_getcpuclockid, clock_getcpuclockid)