+/* clock_getcpuclockid -- Get a clockid_t for process CPU time. Linux version.
+ Copyright (C) 2004 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#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 !(__ASSUME_POSIX_TIMERS > 0)
+ extern int __libc_missing_posix_timers attribute_hidden;
+ if (__libc_missing_posix_timers && !__libc_missing_posix_cpu_timers)
+ __libc_missing_posix_cpu_timers = 1;
+# endif
+ 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 !(__ASSUME_POSIX_TIMERS > 0)
+ if (INTERNAL_SYSCALL_ERRNO (r, err) == ENOSYS)
+ {
+ /* The kernel doesn't support these calls at all. */
+ __libc_missing_posix_timers = 1;
+ __libc_missing_posix_cpu_timers = 1;
+ }
+ else
+# endif
+ 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;
+ }
+#else
+ /* We don't have a timer for that. */
+ return ENOENT;
+#endif
+}