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1/* $OpenBSD: login.c,v 1.11 2015/12/28 20:11:36 guenther Exp $ */
2/*
3 * Copyright (c) 1988, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/types.h>
32
33#include <fcntl.h>
34#include <unistd.h>
35#include <stdlib.h>
36#include <utmp.h>
37#include <stdio.h>
38#include <string.h>
39
40#include "util.h"
41
42void
43login(struct utmp *utp)
44{
45 struct utmp old_ut;
46 int fd, tty;
47 off_t pos;
48
49 tty = ttyslot();
50 if (tty > 0 && (fd = open(_PATH_UTMP, O_RDWR|O_CREAT|O_CLOEXEC, 0644))
51 >= 0) {
52 /*
53 * Prevent luser from zero'ing out ut_host.
54 * If the new ut_line is empty but the old one is not
55 * and ut_line and ut_name match, preserve the old ut_line.
56 */
57 pos = (off_t)tty * sizeof(struct utmp);
58 if (utp->ut_host[0] == '\0' &&
59 pread(fd, &old_ut, sizeof(struct utmp), pos) ==
60 sizeof(struct utmp) &&
61 old_ut.ut_host[0] != '\0' &&
62 strncmp(old_ut.ut_line, utp->ut_line, UT_LINESIZE) == 0 &&
63 strncmp(old_ut.ut_name, utp->ut_name, UT_NAMESIZE) == 0)
64 (void)memcpy(utp->ut_host, old_ut.ut_host, UT_HOSTSIZE);
65 (void)pwrite(fd, utp, sizeof(struct utmp), pos);
66 (void)close(fd);
67 }
68 if ((fd = open(_PATH_WTMP, O_WRONLY|O_APPEND|O_CLOEXEC)) >= 0) {
69 (void)write(fd, utp, sizeof(struct utmp));
70 (void)close(fd);
71 }
72}