usr.bin/users/users.c

   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. 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  * @(#) Copyright (c) 1980, 1987, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)users.c  8.1 (Berkeley) 6/6/93
  31  * $FreeBSD: src/usr.bin/users/users.c,v 1.8 2002/09/04 23:29:09 dwmalone Exp $
  32  * $DragonFly: src/usr.bin/users/users.c,v 1.5 2007/10/02 16:38:10 swildner Exp $
  33  */
  34
  35 #include <sys/types.h>
  36 #include <err.h>
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40 #include <unistd.h>
  41 #include "utmpentry.h"
  42
  43 typedef char   namebuf[32];
  44
  45 static int scmp(const void *, const void *);
  46 static void usage(void);
  47
  48 int
  49 main(int argc, char **argv)
  50 {
  51         struct utmpentry *ep = NULL;    /* avoid gcc warnings */
  52         namebuf *names = NULL;
  53         int ncnt = 0;
  54         int nmax = 0;
  55         int cnt;
  56         int ch;
  57
  58         while ((ch = getopt(argc, argv, "")) != -1) {
  59                 switch(ch) {
  60                 default:
  61                         usage();
  62                 }
  63         }
  64         argc -= optind;
  65         argv += optind;
  66
  67         getutentries(NULL, &ep);
  68         for (; ep; ep = ep->next) {
  69                 if (ncnt >= nmax) {
  70                         nmax += 32;
  71                         names = realloc(names,
  72                                 sizeof (*names) * nmax);
  73                         if (names == NULL)
  74                                 err(1, "realloc");
  75                 }
  76                 strcpy(names[ncnt], ep->name);
  77                 ++ncnt;
  78         }
  79         if (ncnt) {
  80                 qsort(names, ncnt, 32, scmp);
  81                 printf("%.*s", 32, names[0]);
  82                 for (cnt = 1; cnt < ncnt; ++cnt) {
  83                         if (strcmp(names[cnt], names[cnt - 1]))
  84                                 printf(" %.*s", 32, names[cnt]);
  85                 }
  86                 printf("\n");
  87         }
  88         exit(0);
  89 }
  90
  91 static void
  92 usage(void)
  93 {
  94         fprintf(stderr, "usage: users\n");
  95         exit(1);
  96 }
  97
  98 int
  99 scmp(const void *p, const void *q)
 100 {
 101         return(strncmp(p, q, 32));
 102 }