users.c revision 102944 
1/*
2 * Copyright (c) 1980, 1987, 1993
3 *	The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1980, 1987, 1993\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "@(#)users.c	8.1 (Berkeley) 6/6/93";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/usr.bin/users/users.c 102944 2002-09-04 23:29:10Z dwmalone $";
46#endif /* not lint */
47
48#include <sys/types.h>
49#include <err.h>
50#include <stdio.h>
51#include <stdlib.h>
52#include <string.h>
53#include <unistd.h>
54#include <utmp.h>
55
56typedef char   namebuf[UT_NAMESIZE];
57
58int scmp(const void *, const void *);
59static void usage(void);
60
61int
62main(int argc, char **argv)
63{
64	namebuf *names = NULL;
65	int ncnt = 0;
66	int nmax = 0;
67	int cnt;
68	struct utmp utmp;
69	int ch;
70
71	while ((ch = getopt(argc, argv, "")) != -1)
72		switch(ch) {
73		case '?':
74		default:
75			usage();
76		}
77	argc -= optind;
78	argv += optind;
79
80	if (!freopen(_PATH_UTMP, "r", stdin))
81		errx(1, "can't open %s", _PATH_UTMP);
82	while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
83		if (*utmp.ut_name) {
84			if (ncnt >= nmax) {
85				nmax += 32;
86				names = realloc(names, sizeof (*names) * nmax);
87				if (!names) {
88					errx(1, "realloc");
89					/* NOTREACHED */
90				}
91			}
92			(void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
93			++ncnt;
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
107static void
108usage(void)
109{
110	(void)fprintf(stderr, "usage: users\n");
111	exit(1);
112}
113
114int
115scmp(const void *p, const void *q)
116{
117	return(strncmp(p, q, UT_NAMESIZE));
118}
119