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utmp_update.c revision 1.3 
      1 /*	$NetBSD: utmp_update.c,v 1.3 2002/08/09 10:01:53 soren 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 <pwd.h>
     45 #include <utmpx.h>
     46 #include <stdlib.h>
     47 #include <string.h>
     48 #include <unistd.h>
     49 
     50 int main(int, char *[]);
     51 
     52 int
     53 main(int argc, char *argv[])
     54 {
     55 	struct utmpx *utx;
     56 	size_t len;
     57 	struct passwd *pwd;
     58 	struct stat st;
     59 
     60 	if (argc != 1) {
     61 		(void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n",
     62 			getprogname());
     63 		exit(1);
     64 	}
     65 
     66 	len = strlen(argv[1]);
     67 
     68 	if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx))
     69 		errx(1, "Bad argument");
     70 
     71 	if ((utx = malloc(len)) == NULL)
     72 		err(1, NULL);
     73 
     74 	if (strunvis((char *)utx, argv[1]) != sizeof(*utx))
     75 		errx(1, "Decoding error");
     76 
     77 	switch (utx->ut_type) {
     78 	case USER_PROCESS:
     79 	case DEAD_PROCESS:
     80 		break;
     81 	default:
     82 		errx(1, "Invalid utmpx type %d", (int)utx->ut_type);
     83 	}
     84 
     85 	if ((pwd = getpwuid(getuid())) == NULL)
     86 		errx(1, "User %lu does not exist in password database",
     87 		    (long)getuid());
     88 
     89 	if (strcmp(pwd->pw_name, utx->ut_name) != 0)
     90 		errx(1, "Current user `%s' does not match `%s' in utmpx entry",
     91 		    pwd->pw_name, utx->ut_name);
     92 
     93 	if (stat(utx->ut_line, &st) == -1)
     94 		err(1, "Cannot stat `%s'", utx->ut_line);
     95 
     96 	if (!S_ISCHR(st.st_mode))
     97 		errx(1, "%s: Not a character device", utx->ut_line);
     98 
     99 	/*
    100 	 * to check if the tty is writable here is problematic. First we
    101 	 * don't even know if it is a tty, secondly we are setuid so it
    102 	 * is not trivial to use access
    103 	 */
    104 
    105 	pututxline(utx);
    106 
    107 	return 0;
    108 }
    109