xref: /freebsd/usr.bin/users/users.cc (revision 580744621f33383027108364dcadad718df46ffe)
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 <capsicum_helpers.h>
36 #include <err.h>
37 #include <errno.h>
38 #include <utmpx.h>
39 
40 #include <algorithm>
41 #include <iostream>
42 #include <iterator>
43 #include <set>
44 #include <string>
45 using namespace std;
46 
47 int
48 main(int argc, char **)
49 {
50 	struct utmpx *ut;
51 	set<string> names;
52 
53 	if (argc > 1) {
54 		cerr << "usage: users" << endl;
55 		return (1);
56 	}
57 
58 	setutxent();
59 
60 	if (caph_enter())
61 		err(1, "Failed to enter capability mode.");
62 
63 	while ((ut = getutxent()) != NULL)
64 		if (ut->ut_type == USER_PROCESS)
65 			names.insert(ut->ut_user);
66 	endutxent();
67 
68 	if (!names.empty()) {
69 		set<string>::iterator last = names.end();
70 		--last;
71 		copy(names.begin(), last, ostream_iterator<string>(cout, " "));
72 		cout << *last << endl;
73 	}
74 }
75