openntpd-openbsd/src/lib/libutil/logwtmp.c

/*	$OpenBSD: logwtmp.c,v 1.11 2019/06/28 13:32:43 deraadt Exp $	*/
/*
 * Copyright (c) 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>

#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <utmp.h>

#include "util.h"

void
logwtmp(const char *line, const char *name, const char *host)
{
	struct stat buf;
	struct utmp ut;
	int fd;

	if ((fd = open(_PATH_WTMP, O_WRONLY|O_APPEND|O_CLOEXEC)) == -1)
		return;
	if (fstat(fd, &buf) == 0) {
		(void) strncpy(ut.ut_line, line, sizeof(ut.ut_line));
		(void) strncpy(ut.ut_name, name, sizeof(ut.ut_name));
		(void) strncpy(ut.ut_host, host, sizeof(ut.ut_host));
		(void) time(&ut.ut_time);
		if (write(fd, &ut, sizeof(struct utmp)) !=
		    sizeof(struct utmp))
			(void) ftruncate(fd, buf.st_size);
	}
	(void) close(fd);
}