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users.c revision 1.6 
      1 /*	$NetBSD: users.c,v 1.6 1997/10/20 02:41:22 lukem Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1980, 1987, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 __COPYRIGHT("@(#) Copyright (c) 1980, 1987, 1993\n\
     39 	The Regents of the University of California.  All rights reserved.\n");
     40 #endif /* not lint */
     41 
     42 #ifndef lint
     43 #if 0
     44 static char sccsid[] = "@(#)users.c	8.1 (Berkeley) 6/6/93";
     45 #endif
     46 __RCSID("$NetBSD: users.c,v 1.6 1997/10/20 02:41:22 lukem Exp $");
     47 #endif /* not lint */
     48 
     49 #include <sys/types.h>
     50 #include <utmp.h>
     51 #include <stdio.h>
     52 #include <stdlib.h>
     53 #include <string.h>
     54 #include <err.h>
     55 
     56 typedef char	namebuf[UT_NAMESIZE];
     57 
     58 int	main __P((int, char **));
     59 int scmp __P((const void *, const void *));
     60 
     61 int
     62 main(argc, argv)
     63 	int argc;
     64 	char **argv;
     65 {
     66 	namebuf *names = NULL;
     67 	int ncnt = 0;
     68 	int nmax = 0;
     69 	int cnt;
     70 	struct utmp utmp;
     71 	int ch;
     72 
     73 	while ((ch = getopt(argc, argv, "")) != -1)
     74 		switch(ch) {
     75 		case '?':
     76 		default:
     77 			(void)fprintf(stderr, "usage: users\n");
     78 			exit(1);
     79 		}
     80 	argc -= optind;
     81 	argv += optind;
     82 
     83 	if (!freopen(_PATH_UTMP, "r", stdin)) {
     84 		err(1, "can't open %s", _PATH_UTMP);
     85 		/* NOTREACHED */
     86 	}
     87 
     88 	while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
     89 		if (*utmp.ut_name) {
     90 			if (ncnt >= nmax) {
     91 				nmax += 32;
     92 				names = realloc(names,
     93 					sizeof (*names) * nmax);
     94 
     95 				if (!names) {
     96 					err(1, "realloc");
     97 					/* NOTREACHED */
     98 				}
     99 			}
    100 
    101 			(void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
    102 			++ncnt;
    103 		}
    104 	}
    105 
    106 	if (ncnt) {
    107 		qsort(names, ncnt, UT_NAMESIZE, scmp);
    108 		(void)printf("%.*s", UT_NAMESIZE, names[0]);
    109 		for (cnt = 1; cnt < ncnt; ++cnt)
    110 			if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
    111 				(void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
    112 		(void)printf("\n");
    113 	}
    114 	exit(0);
    115 }
    116 
    117 int
    118 scmp(p, q)
    119 	const void *p, *q;
    120 {
    121 	return(strncmp((char *) p, (char *) q, UT_NAMESIZE));
    122 }
    123