1 /* clock_getcpuclockid -- Get a clockid_t for process CPU time. Linux version.
2 Copyright (C) 2004, 2005 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 <sysdep.h>
22 #include <unistd.h>
23 #include <bits/kernel-features.h>
24 #include "kernel-posix-cpu-timers.h"
25
26 #ifndef HAS_CPUCLOCK
27 # define HAS_CPUCLOCK 1
28 #endif
29
30 int
clock_getcpuclockid(pid_t pid,clockid_t * clock_id)31 clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
32 {
33 #ifdef __NR_clock_getres
34 /* The clockid_t value is a simple computation from the PID.
35 But we do a clock_getres call to validate it. */
36
37 const clockid_t pidclock = MAKE_PROCESS_CPUCLOCK (pid, CPUCLOCK_SCHED);
38
39 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
40 extern int __libc_missing_posix_cpu_timers attribute_hidden;
41 # if !(__ASSUME_POSIX_TIMERS > 0)
42 extern int __libc_missing_posix_timers attribute_hidden;
43 if (__libc_missing_posix_timers && !__libc_missing_posix_cpu_timers)
44 __libc_missing_posix_cpu_timers = 1;
45 # endif
46 if (!__libc_missing_posix_cpu_timers)
47 # endif
48 {
49 INTERNAL_SYSCALL_DECL (err);
50 int r = INTERNAL_SYSCALL (clock_getres, err, 2, pidclock, NULL);
51 if (!INTERNAL_SYSCALL_ERROR_P (r, err))
52 {
53 *clock_id = pidclock;
54 return 0;
55 }
56
57 # if !(__ASSUME_POSIX_TIMERS > 0)
58 if (INTERNAL_SYSCALL_ERRNO (r, err) == ENOSYS)
59 {
60 /* The kernel doesn't support these calls at all. */
61 __libc_missing_posix_timers = 1;
62 __libc_missing_posix_cpu_timers = 1;
63 }
64 else
65 # endif
66 if (INTERNAL_SYSCALL_ERRNO (r, err) == EINVAL)
67 {
68 # if !(__ASSUME_POSIX_CPU_TIMERS > 0)
69 if (pidclock == MAKE_PROCESS_CPUCLOCK (0, CPUCLOCK_SCHED)
70 || INTERNAL_SYSCALL_ERROR_P (INTERNAL_SYSCALL
71 (clock_getres, err, 2,
72 MAKE_PROCESS_CPUCLOCK
73 (0, CPUCLOCK_SCHED), NULL),
74 err))
75 /* The kernel doesn't support these clocks at all. */
76 __libc_missing_posix_cpu_timers = 1;
77 else
78 # endif
79 /* The clock_getres system call checked the PID for us. */
80 return ESRCH;
81 }
82 else
83 return INTERNAL_SYSCALL_ERRNO (r, err);
84 }
85 #endif
86
87 /* We don't allow any process ID but our own. */
88 if (pid != 0 && pid != getpid ())
89 return EPERM;
90
91 #ifdef CLOCK_PROCESS_CPUTIME_ID
92 if (HAS_CPUCLOCK)
93 {
94 /* Store the number. */
95 *clock_id = CLOCK_PROCESS_CPUTIME_ID;
96
97 return 0;
98 }
99 #endif
100
101 /* We don't have a timer for that. */
102 return ENOENT;
103 }
104