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/* clock_getcpuclockid -- Get a clockid_t for process CPU time. Linux version.
Copyright (C) 2004-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <kernel-features.h>
#include "kernel-posix-cpu-timers.h"
#ifndef HAS_CPUCLOCK
# define HAS_CPUCLOCK 1
#endif
int
clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
{
#ifdef __NR_clock_getres
/* The clockid_t value is a simple computation from the PID.
But we do a clock_getres call to validate it. */
const clockid_t pidclock = MAKE_PROCESS_CPUCLOCK (pid, CPUCLOCK_SCHED);
# if !(__ASSUME_POSIX_CPU_TIMERS > 0)
extern int __libc_missing_posix_cpu_timers attribute_hidden;
if (!__libc_missing_posix_cpu_timers)
# endif
{
INTERNAL_SYSCALL_DECL (err);
int r = INTERNAL_SYSCALL (clock_getres, err, 2, pidclock, NULL);
if (!INTERNAL_SYSCALL_ERROR_P (r, err))
{
*clock_id = pidclock;
return 0;
}
if (INTERNAL_SYSCALL_ERRNO (r, err) == EINVAL)
{
# if !(__ASSUME_POSIX_CPU_TIMERS > 0)
if (pidclock == MAKE_PROCESS_CPUCLOCK (0, CPUCLOCK_SCHED)
|| INTERNAL_SYSCALL_ERROR_P (INTERNAL_SYSCALL
(clock_getres, err, 2,
MAKE_PROCESS_CPUCLOCK
(0, CPUCLOCK_SCHED), NULL),
err))
/* The kernel doesn't support these clocks at all. */
__libc_missing_posix_cpu_timers = 1;
else
# endif
/* The clock_getres system call checked the PID for us. */
return ESRCH;
}
else
return INTERNAL_SYSCALL_ERRNO (r, err);
}
#endif
/* We don't allow any process ID but our own. */
if (pid != 0 && pid != getpid ())
return EPERM;
#ifdef CLOCK_PROCESS_CPUTIME_ID
if (HAS_CPUCLOCK)
{
/* Store the number. */
*clock_id = CLOCK_PROCESS_CPUTIME_ID;
return 0;
}
#endif
/* We don't have a timer for that. */
return ENOENT;
}
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