lib/libc/sys/ntp_adjtime.c

   1 /*      $NetBSD: ntp_adjtime.c,v 1.11 2007/11/23 12:39:15 uebayasi 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 1.11 2007/11/23 12:39:15 uebayasi 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, 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                 (void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC);
  98         }
  99
 100         /*
 101          * If __clockctl_fd >=0, clockctl has already been open
 102          * and used, so we carry on using it.
 103          */
 104         args.tp = tp;
 105         error = ioctl(__clockctl_fd, CLOCKCTL_NTP_ADJTIME, &args);
 106
 107         /*
 108          * There is no way to get retval set through ioctl(), hence we
 109          * have to handle it here, using args.retval
 110          */
 111         if (error == 0) {
 112                 rv = (int)args.retval;
 113                 return rv;
 114         }
 115
 116         return error;
 117 }