1 /* $OpenBSD: users.c,v 1.16 2022/12/04 23:50:48 cheloha 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
main(int argc,char * argv[])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 (unveil(_PATH_UTMP, "r") == -1)
57 err(1, "unveil %s", _PATH_UTMP);
58 if (pledge("stdio rpath", NULL) == -1)
59 err(1, "pledge");
60
61 while ((ch = getopt(argc, argv, "")) != -1)
62 switch(ch) {
63 default:
64 (void)fprintf(stderr, "usage: users\n");
65 exit(1);
66 }
67 argc -= optind;
68 argv += optind;
69
70 if (!freopen(_PATH_UTMP, "r", stdin)) {
71 err(1, "can't open %s", _PATH_UTMP);
72 /* NOTREACHED */
73 }
74
75 while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
76 if (*utmp.ut_name) {
77 if (ncnt >= nmax) {
78 size_t newmax = nmax + 32;
79 namebuf *newnames;
80
81 newnames = reallocarray(names, newmax,
82 sizeof(*names));
83
84 if (newnames == NULL) {
85 err(1, NULL);
86 /* NOTREACHED */
87 }
88 names = newnames;
89 nmax = newmax;
90 }
91
92 (void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
93 ++ncnt;
94 }
95 }
96
97 if (ncnt) {
98 qsort(names, ncnt, UT_NAMESIZE, scmp);
99 (void)printf("%.*s", UT_NAMESIZE, names[0]);
100 for (cnt = 1; cnt < ncnt; ++cnt)
101 if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
102 (void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
103 (void)printf("\n");
104 }
105 exit(0);
106 }
107
108 int
scmp(const void * p,const void * q)109 scmp(const void *p, const void *q)
110 {
111 return(strncmp((char *) p, (char *) q, UT_NAMESIZE));
112 }
113