users.cc revision 330464 
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 * 4. 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/capsicum.h>
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/11/usr.bin/users/users.cc 330464 2018-03-05 08:27:29Z eadler $");
33
34#include <err.h>
35#include <errno.h>
36#include <utmpx.h>
37
38#include <algorithm>
39#include <iostream>
40#include <iterator>
41#include <set>
42#include <string>
43using namespace std;
44
45int
46main(int argc, char **)
47{
48	struct utmpx *ut;
49	set<string> names;
50
51	if (argc > 1) {
52		cerr << "usage: users" << endl;
53		return (1);
54	}
55
56	setutxent();
57
58	if (cap_enter() < 0 && errno != ENOSYS)
59		err(1, "Failed to enter capability mode.");
60
61	while ((ut = getutxent()) != NULL)
62		if (ut->ut_type == USER_PROCESS)
63			names.insert(ut->ut_user);
64	endutxent();
65
66	if (!names.empty()) {
67		set<string>::iterator last = names.end();
68		--last;
69		copy(names.begin(), last, ostream_iterator<string>(cout, " "));
70		cout << *last << endl;
71	}
72}
73