Home | History | Annotate | Line # | Download | only in sys
adjtime.c revision 1.8 
      1 /*	$NetBSD: adjtime.c,v 1.8 2006/10/07 20:02:01 kardel 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 1.8 2006/10/07 20:02:01 kardel 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
     59 adjtime(delta, olddelta)
     60 	const struct timeval *delta;
     61 	struct timeval *olddelta;
     62 {
     63 	struct clockctl_adjtime args;
     64 	quad_t q;
     65 	int rv;
     66 
     67 	/*
     68 	 * we always attempt the syscall first and switch to
     69 	 * clockctl if that fails with EPERM
     70 	 */
     71 	if (__clockctl_fd == -1) {
     72 		q = __syscall((quad_t)SYS_adjtime, delta, olddelta);
     73 		if (/* LINTED constant */ sizeof (quad_t) == sizeof (register_t)
     74 		    || /* LINTED constant */ BYTE_ORDER == LITTLE_ENDIAN)
     75 			rv = (int)q;
     76 		else
     77 			rv = (int)((u_quad_t)q >> 32);
     78 
     79 		/*
     80 		 * try via clockctl if the call fails with EPERM
     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 failure.
     88 		 */
     89 		__clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY, 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 		(void) fcntl(__clockctl_fd, F_SETFD, FD_CLOEXEC);
     97 	}
     98 
     99 	/*
    100 	 * If __clockctl_fd >=0, clockctl has already been open
    101 	 * and used, so we carry on using it.
    102 	 */
    103 	args.delta = delta;
    104 	args.olddelta = olddelta;
    105 	return ioctl(__clockctl_fd, CLOCKCTL_ADJTIME, &args);
    106 }
    107