1 /* $NetBSD: ntp_adjtime.c,v 1.13 2012/03/20 16:26:12 matt Exp $ */
2
3 /*
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Emmanuel Dreyfus.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 #if defined(LIBC_SCCS) && !defined(lint)
36 __RCSID("$NetBSD: ntp_adjtime.c,v 1.13 2012/03/20 16:26:12 matt Exp $");
37 #endif /* LIBC_SCCS and not lint */
38
39 #include "namespace.h"
40 #include <sys/types.h>
41 #include <sys/time.h>
42 #include <sys/timex.h>
43 #include <sys/ioctl.h>
44 #include <sys/syscall.h>
45
46 #include <sys/clockctl.h>
47
48 #include <errno.h>
49 #include <fcntl.h>
50 #include <paths.h>
51 #include <string.h>
52 #include <unistd.h>
53
54 #ifdef __weak_alias
55 __weak_alias(ntp_adjtime,_ntp_adjtime)
56 #endif
57
58 extern int __clockctl_fd;
59
60 int __ntp_adjtime(struct timex *);
61
62 int
ntp_adjtime(struct timex * tp)63 ntp_adjtime(struct timex *tp)
64 {
65 struct clockctl_ntp_adjtime args;
66 int error;
67 int rv;
68
69 /*
70 * we always attempt to use the syscall unless we had to
71 * use the clockctl device before
72 *
73 * ntp_adjtime() is callable for mortals if tp->modes == 0 !
74 */
75 if (__clockctl_fd == -1) {
76 rv = __ntp_adjtime(tp);
77
78 /*
79 * if we fail with EPERM we try the clockctl device
80 */
81 if (rv != -1 || errno != EPERM)
82 return rv;
83
84 /*
85 * If this fails, it means that we are not root
86 * and we cannot open clockctl. This is a true
87 * failure.
88 */
89 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY | O_CLOEXEC, 0);
90 if (__clockctl_fd == -1) {
91 /* original error was EPERM - don't leak open errors */
92 errno = EPERM;
93 return -1;
94 }
95 }
96
97 /*
98 * If __clockctl_fd >=0, clockctl has already been open
99 * and used, so we carry on using it.
100 */
101 args.tp = tp;
102 error = ioctl(__clockctl_fd, CLOCKCTL_NTP_ADJTIME, &args);
103
104 /*
105 * There is no way to get retval set through ioctl(), hence we
106 * have to handle it here, using args.retval
107 */
108 if (error == 0) {
109 rv = (int)args.retval;
110 return rv;
111 }
112
113 return error;
114 }
115