xref: /freebsd/usr.bin/users/users.cc (revision f39bffc62c1395bde25d152c7f68fdf7cbaab414)
1 /*-
2  * Copyright (c) 2014 Pietro Cerutti <gahr@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include <sys/capsicum.h>
34 
35 #include <err.h>
36 #include <errno.h>
37 #include <utmpx.h>
38 
39 #include <algorithm>
40 #include <iostream>
41 #include <iterator>
42 #include <set>
43 #include <string>
44 using namespace std;
45 
46 int
47 main(int argc, char **)
48 {
49 	struct utmpx *ut;
50 	set<string> names;
51 
52 	if (argc > 1) {
53 		cerr << "usage: users" << endl;
54 		return (1);
55 	}
56 
57 	setutxent();
58 
59 	if (cap_enter() < 0 && errno != ENOSYS)
60 		err(1, "Failed to enter capability mode.");
61 
62 	while ((ut = getutxent()) != NULL)
63 		if (ut->ut_type == USER_PROCESS)
64 			names.insert(ut->ut_user);
65 	endutxent();
66 
67 	if (!names.empty()) {
68 		set<string>::iterator last = names.end();
69 		--last;
70 		copy(names.begin(), last, ostream_iterator<string>(cout, " "));
71 		cout << *last << endl;
72 	}
73 }
74