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adjtime.c revision 1.9 
      1 /*	$NetBSD: adjtime.c,v 1.9 2007/11/22 21:11:31 dsl 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 1.9 2007/11/22 21:11:31 dsl 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 #ifdef __weak_alias
     53 __weak_alias(adjtime,_adjtime)
     54 #endif
     55 
     56 extern int __clockctl_fd;
     57 
     58 int __adjtime(const struct timeval *delta, struct timeval *olddelta);
     59 
     60 int
     61 adjtime(delta, olddelta)
     62 	const struct timeval *delta;
     63 	struct timeval *olddelta;
     64 {
     65 	struct clockctl_adjtime args;
     66 	int rv;
     67 
     68 	/*
     69 	 * we always attempt the syscall first and switch to
     70 	 * clockctl if that fails with EPERM
     71 	 */
     72 	if (__clockctl_fd == -1) {
     73 		rv = __adjtime(delta, olddelta);
     74 
     75 		/*
     76 		 * try via clockctl if the call fails with EPERM
     77 		 */
     78 		if (rv != -1 || errno != EPERM)
     79 			return rv;
     80 
     81 		/*
     82 		 * If this fails, it means that we are not root
     83 		 * and we cannot open clockctl. This is a failure.
     84 		 */
     85 		__clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 0);
     86 		if (__clockctl_fd == -1) {
     87 			/* original error was EPERM - don't leak open errors */
     88 			errno = EPERM;
     89 			return -1;
     90 		}
     91 
     92 		(void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC);
     93 	}
     94 
     95 	/*
     96 	 * If __clockctl_fd >=0, clockctl has already been open
     97 	 * and used, so we carry on using it.
     98 	 */
     99 	args.delta = delta;
    100 	args.olddelta = olddelta;
    101 	return ioctl(__clockctl_fd, CLOCKCTL_ADJTIME, &args);
    102 }
    103