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      1 /*	$NetBSD: clock_settime.c,v 1.12 2011/10/15 23:00:02 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: clock_settime.c,v 1.12 2011/10/15 23:00:02 christos Exp $");
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include "namespace.h"
     40 
     41 #include <sys/types.h>
     42 #include <sys/ioctl.h>
     43 #include <sys/syscall.h>
     44 
     45 #include <errno.h>
     46 #include <fcntl.h>
     47 #include <paths.h>
     48 #include <string.h>
     49 #include <time.h>
     50 #include <unistd.h>
     51 
     52 #include <sys/clockctl.h>
     53 
     54 extern int __clockctl_fd;
     55 
     56 int ____clock_settime50(clockid_t, const struct timespec *);
     57 
     58 int
     59 clock_settime(clockid_t clock_id, const struct timespec *tp)
     60 {
     61 	struct clockctl_clock_settime args;
     62 	int rv;
     63 
     64 	/*
     65 	 * always try the syscall first and attempt to switch to
     66 	 * clockctl if that fails.
     67 	 */
     68 	if (__clockctl_fd == -1) {
     69 		rv = ____clock_settime50(clock_id, tp);
     70 
     71 		/*
     72 		 * return unless we failed with EPERM
     73 		 */
     74 		if (rv != -1 || errno != EPERM)
     75 			return rv;
     76 
     77 		/*
     78 		 * If this fails, it means that we are not root
     79 		 * and we cannot open clockctl. This is a failure.
     80 		 */
     81 		__clockctl_fd = open(_PATH_CLOCKCTL, O_WRONLY | O_CLOEXEC, 0);
     82 		if (__clockctl_fd == -1) {
     83 			/* original error was EPERM - don't leak open errors */
     84 			errno = EPERM;
     85 			return -1;
     86 		}
     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.clock_id = clock_id;
     94 	args.tp = tp;
     95 	return ioctl(__clockctl_fd, CLOCKCTL_CLOCK_SETTIME, &args);
     96 }
     97