lib/libc/sys/adjtime.c

   1 /*      $NetBSD: adjtime.c,v 1.11 2009/01/11 02:46:30 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: adjtime.c,v 1.11 2009/01/11 02:46:30 christos Exp $");
  37 #endif /* LIBC_SCCS and not lint */
  38
  39 #include "namespace.h"
  40 #include <errno.h>
  41 #include <fcntl.h>
  42 #include <paths.h>
  43 #include <unistd.h>
  44 #include <time.h>
  45 #include <string.h>
  46 #include <sys/types.h>
  47 #include <sys/ioctl.h>
  48 #include <sys/syscall.h>
  49
  50 #include <sys/clockctl.h>
  51
  52 extern int __clockctl_fd;
  53
  54 int ____adjtime50(const struct timeval *, struct timeval *);
  55
  56 int
  57 adjtime(const struct timeval *delta, struct timeval *olddelta)
  58 {
  59         struct clockctl_adjtime args;
  60         int rv;
  61
  62         /*
  63          * we always attempt the syscall first and switch to
  64          * clockctl if that fails with EPERM
  65          */
  66         if (__clockctl_fd == -1) {
  67                 rv = ____adjtime50(delta, olddelta);
  68
  69                 /*
  70                  * try via clockctl if the call fails with EPERM
  71                  */
  72                 if (rv != -1 || errno != EPERM)
  73                         return rv;
  74
  75                 /*
  76                  * If this fails, it means that we are not root
  77                  * and we cannot open clockctl. This is a failure.
  78                  */
  79                 __clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0);
  80                 if (__clockctl_fd == -1) {
  81                         /* original error was EPERM - don't leak open errors */
  82                         errno = EPERM;
  83                         return -1;
  84                 }
  85
  86                 (void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC);
  87         }
  88
  89         /*
  90          * If __clockctl_fd >=0, clockctl has already been open
  91          * and used, so we carry on using it.
  92          */
  93         args.delta = delta;
  94         args.olddelta = olddelta;
  95         return ioctl(__clockctl_fd, CLOCKCTL_ADJTIME, &args);
  96 }