1 /* $OpenBSD: users.c,v 1.13 2015/10/09 01:37:09 deraadt Exp $ */ 2 /* $NetBSD: users.c,v 1.5 1994/12/20 15:58:19 jtc Exp $ */ 3 4 /* 5 * Copyright (c) 1980, 1987, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 35 #include <err.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <unistd.h> 40 #include <utmp.h> 41 42 typedef char namebuf[UT_NAMESIZE]; 43 44 int scmp(const void *, const void *); 45 46 int 47 main(int argc, char *argv[]) 48 { 49 namebuf *names = NULL; 50 int ncnt = 0; 51 int nmax = 0; 52 int cnt; 53 struct utmp utmp; 54 int ch; 55 56 if (pledge("stdio rpath", NULL) == -1) 57 err(1, "pledge"); 58 59 while ((ch = getopt(argc, argv, "")) != -1) 60 switch(ch) { 61 case '?': 62 default: 63 (void)fprintf(stderr, "usage: users\n"); 64 exit(1); 65 } 66 argc -= optind; 67 argv += optind; 68 69 if (!freopen(_PATH_UTMP, "r", stdin)) { 70 err(1, "can't open %s", _PATH_UTMP); 71 /* NOTREACHED */ 72 } 73 74 while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) { 75 if (*utmp.ut_name) { 76 if (ncnt >= nmax) { 77 size_t newmax = nmax + 32; 78 namebuf *newnames; 79 80 newnames = reallocarray(names, newmax, 81 sizeof(*names)); 82 83 if (newnames == NULL) { 84 err(1, NULL); 85 /* NOTREACHED */ 86 } 87 names = newnames; 88 nmax = newmax; 89 } 90 91 (void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE); 92 ++ncnt; 93 } 94 } 95 96 if (ncnt) { 97 qsort(names, ncnt, UT_NAMESIZE, scmp); 98 (void)printf("%.*s", UT_NAMESIZE, names[0]); 99 for (cnt = 1; cnt < ncnt; ++cnt) 100 if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE)) 101 (void)printf(" %.*s", UT_NAMESIZE, names[cnt]); 102 (void)printf("\n"); 103 } 104 exit(0); 105 } 106 107 int 108 scmp(const void *p, const void *q) 109 { 110 return(strncmp((char *) p, (char *) q, UT_NAMESIZE)); 111 } 112