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 42 void 43 login(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 } 73