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ntp_adjtime.c revision 1.12 
      1 /*	$NetBSD: ntp_adjtime.c,v 1.12 2011/10/15 23:00:02 christos 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 1.12 2011/10/15 23:00:02 christos 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
     63 ntp_adjtime(tp)
     64 	struct timex *tp;
     65 {
     66 	struct clockctl_ntp_adjtime args;
     67 	int error;
     68 	int rv;
     69 
     70 	/*
     71 	 * we always attempt to use the syscall unless we had to
     72 	 * use the clockctl device before
     73 	 *
     74 	 * ntp_adjtime() is callable for mortals if tp->modes == 0 !
     75 	 */
     76 	if (__clockctl_fd == -1) {
     77 		rv = __ntp_adjtime(tp);
     78 
     79 		/*
     80 		 * if we fail with EPERM we try the clockctl device
     81 		 */
     82 		if (rv != -1 || errno != EPERM)
     83 			return rv;
     84 
     85 		/*
     86 		 * If this fails, it means that we are not root
     87 		 * and we cannot open clockctl. This is a true
     88 		 * failure.
     89 		 */
     90 		__clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY | O_CLOEXEC, 0);
     91 		if (__clockctl_fd == -1) {
     92 			/* original error was EPERM - don't leak open errors */
     93 			errno = EPERM;
     94 			return -1;
     95 		}
     96 	}
     97 
     98 	/*
     99 	 * If __clockctl_fd >=0, clockctl has already been open
    100 	 * and used, so we carry on using it.
    101 	 */
    102 	args.tp = tp;
    103 	error = ioctl(__clockctl_fd, CLOCKCTL_NTP_ADJTIME, &args);
    104 
    105 	/*
    106 	 * There is no way to get retval set through ioctl(), hence we
    107 	 * have to handle it here, using args.retval
    108 	 */
    109 	if (error == 0) {
    110 		rv = (int)args.retval;
    111 		return rv;
    112 	}
    113 
    114 	return error;
    115 }
    116