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utmp_update.c revision 1.4 
      1 /*	$NetBSD: utmp_update.c,v 1.4 2002/08/16 20:21:48 itojun Exp $	 */
      2 
      3 /*-
      4  * Copyright (c) 2002 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Christos Zoulas.
      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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/stat.h>
     40 
     41 #include <stdio.h>
     42 #include <vis.h>
     43 #include <err.h>
     44 #include <fcntl.h>
     45 #include <pwd.h>
     46 #include <utmpx.h>
     47 #include <stdlib.h>
     48 #include <string.h>
     49 #include <unistd.h>
     50 
     51 int main(int, char *[]);
     52 
     53 int
     54 main(int argc, char *argv[])
     55 {
     56 	struct utmpx *utx;
     57 	size_t len;
     58 	struct passwd *pwd;
     59 	struct stat st;
     60 	int fd;
     61 	uid_t euid;
     62 
     63 	euid = geteuid();
     64 	if (seteuid(getuid()) == -1)
     65 		err(1, "seteuid");
     66 
     67 	if (argc != 2) {
     68 		(void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n",
     69 			getprogname());
     70 		exit(1);
     71 	}
     72 
     73 	len = strlen(argv[1]);
     74 
     75 	if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx))
     76 		errx(1, "Bad argument");
     77 
     78 	if ((utx = malloc(len)) == NULL)
     79 		err(1, NULL);
     80 
     81 	if (strunvis((char *)utx, argv[1]) != sizeof(*utx))
     82 		errx(1, "Decoding error");
     83 
     84 	switch (utx->ut_type) {
     85 	case USER_PROCESS:
     86 	case DEAD_PROCESS:
     87 		break;
     88 	default:
     89 		errx(1, "Invalid utmpx type %d", (int)utx->ut_type);
     90 	}
     91 
     92 	if ((pwd = getpwuid(getuid())) == NULL)
     93 		errx(1, "User %lu does not exist in password database",
     94 		    (long)getuid());
     95 
     96 	if (strcmp(pwd->pw_name, utx->ut_name) != 0)
     97 		errx(1, "Current user `%s' does not match `%s' in utmpx entry",
     98 		    pwd->pw_name, utx->ut_name);
     99 
    100 	fd = open(utx->ut_line, O_RDONLY, 0);
    101 	if (fd == -1)
    102 		err(1, "Cannot open `%s'", utx->ut_line);
    103 	if (fstat(fd, &st) == -1)
    104 		err(1, "Cannot stat `%s'", utx->ut_line);
    105 	if (st.st_uid != getuid())
    106 		errx(1, "%s: Is not owned by you", utx->ut_line);
    107 	if (!isatty(fd))
    108 		errx(1, "%s: Not a tty device", utx->ut_line);
    109 	close(fd);
    110 	if (access(utx->ut_line, W_OK|R_OK) == -1)
    111 		err(1, "%s", utx->ut_line);
    112 
    113 	(void)seteuid(euid);
    114 	pututxline(utx);
    115 
    116 	return 0;
    117 }
    118