users/users.c

   1 /*      $NetBSD: users.c,v 1.7 1998/02/03 04:19:15 perry 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 1.7 1998/02/03 04:19:15 perry Exp $");
  47 #endif /* not lint */
  48
  49 #include <sys/types.h>
  50
  51 #include <err.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <unistd.h>
  55 #include <string.h>
  56 #include <unistd.h>
  57 #include <utmp.h>
  58
  59 typedef char    namebuf[UT_NAMESIZE];
  60
  61 int     main __P((int, char **));
  62 int scmp __P((const void *, const void *));
  63
  64 int
  65 main(argc, argv)
  66         int argc;
  67         char **argv;
  68 {
  69         namebuf *names = NULL;
  70         int ncnt = 0;
  71         int nmax = 0;
  72         int cnt;
  73         struct utmp utmp;
  74         int ch;
  75
  76         while ((ch = getopt(argc, argv, "")) != -1)
  77                 switch(ch) {
  78                 case '?':
  79                 default:
  80                         (void)fprintf(stderr, "usage: users\n");
  81                         exit(1);
  82                 }
  83         argc -= optind;
  84         argv += optind;
  85
  86         if (!freopen(_PATH_UTMP, "r", stdin)) {
  87                 err(1, "can't open %s", _PATH_UTMP);
  88                 /* NOTREACHED */
  89         }
  90
  91         while (fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1) {
  92                 if (*utmp.ut_name) {
  93                         if (ncnt >= nmax) {
  94                                 nmax += 32;
  95                                 names = realloc(names,
  96                                         sizeof (*names) * nmax);
  97
  98                                 if (!names) {
  99                                         err(1, "realloc");
 100                                         /* NOTREACHED */
 101                                 }
 102                         }
 103
 104                         (void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
 105                         ++ncnt;
 106                 }
 107         }
 108
 109         if (ncnt) {
 110                 qsort(names, ncnt, UT_NAMESIZE, scmp);
 111                 (void)printf("%.*s", UT_NAMESIZE, names[0]);
 112                 for (cnt = 1; cnt < ncnt; ++cnt)
 113                         if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
 114                                 (void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
 115                 (void)printf("\n");
 116         }
 117         exit(0);
 118 }
 119
 120 int
 121 scmp(p, q)
 122         const void *p, *q;
 123 {
 124         return(strncmp((char *) p, (char *) q, UT_NAMESIZE));
 125 }