lib/libc/sys/ntp_adjtime.c

   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
  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 }