src/users.c

   1 /* GNU's users.
   2    Copyright (C) 1992-1999 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by jla; revised by djm */
  19
  20 #include <config.h>
  21 #include <getopt.h>
  22 #include <stdio.h>
  23
  24 #include "error.h"
  25 #include "long-options.h"
  26 #include "readutmp.h"
  27 #include "system.h"
  28
  29 /* The official name of this program (e.g., no `g' prefix).  */
  30 #define PROGRAM_NAME "users"
  31
  32 #define AUTHORS "Joseph Arceneaux and David MacKenzie"
  33
  34 /* The name this program was run with. */
  35 char *program_name;
  36
  37 static struct option const longopts[] =
  38 {
  39   {NULL, 0, NULL, 0}
  40 };
  41
  42 static int
  43 userid_compare (const void *v_a, const void *v_b)
  44 {
  45   char **a = (char **) v_a;
  46   char **b = (char **) v_b;
  47   return strcmp (*a, *b);
  48 }
  49
  50 static void
  51 list_entries_users (int n, const STRUCT_UTMP *this)
  52 {
  53   char **u;
  54   int i;
  55   int n_entries;
  56
  57   n_entries = 0;
  58   u = (char **) xmalloc (n * sizeof (u[0]));
  59   for (i = 0; i < n; i++)
  60     {
  61       if (this->ut_name[0]
  62 #ifdef USER_PROCESS
  63           && this->ut_type == USER_PROCESS
  64 #endif
  65           )
  66         {
  67           char *trimmed_name;
  68
  69           trimmed_name = extract_trimmed_name (this);
  70
  71           u[n_entries] = trimmed_name;
  72           ++n_entries;
  73         }
  74       this++;
  75     }
  76
  77   qsort (u, n_entries, sizeof (u[0]), userid_compare);
  78
  79   for (i = 0; i < n_entries; i++)
  80     {
  81       int c;
  82       fputs (u[i], stdout);
  83       c = (i < n_entries - 1 ? ' ' : '\n');
  84       putchar (c);
  85     }
  86
  87   for (i = 0; i < n_entries; i++)
  88     free (u[i]);
  89   free (u);
  90 }
  91
  92 /* Display a list of users on the system, according to utmp file FILENAME. */
  93
  94 static void
  95 users (const char *filename)
  96 {
  97   int n_users;
  98   STRUCT_UTMP *utmp_buf;
  99   int fail = read_utmp (filename, &n_users, &utmp_buf);
 100
 101   if (fail)
 102     error (1, errno, "%s", filename);
 103
 104   list_entries_users (n_users, utmp_buf);
 105 }
 106
 107 void
 108 usage (int status)
 109 {
 110   if (status != 0)
 111     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 112              program_name);
 113   else
 114     {
 115       printf (_("Usage: %s [OPTION]... [ FILE ]\n"), program_name);
 116       printf (_("\
 117 Output who is currently logged in according to FILE.\n\
 118 If FILE is not specified, use %s.  %s as FILE is common.\n\
 119 \n\
 120       --help        display this help and exit\n\
 121       --version     output version information and exit\n"),
 122               UTMP_FILE, WTMP_FILE);
 123       puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
 124     }
 125   exit (status);
 126 }
 127
 128 int
 129 main (int argc, char **argv)
 130 {
 131   int optc, longind;
 132   program_name = argv[0];
 133   setlocale (LC_ALL, "");
 134   bindtextdomain (PACKAGE, LOCALEDIR);
 135   textdomain (PACKAGE);
 136
 137   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
 138                       AUTHORS, usage);
 139
 140   while ((optc = getopt_long (argc, argv, "", longopts, &longind)) != -1)
 141     {
 142       switch (optc)
 143         {
 144         case 0:
 145           break;
 146
 147         default:
 148           usage (1);
 149         }
 150     }
 151
 152   switch (argc - optind)
 153     {
 154     case 0:                     /* users */
 155       users (UTMP_FILE);
 156       break;
 157
 158     case 1:                     /* users <utmp file> */
 159       users (argv[optind]);
 160       break;
 161
 162     default:                    /* lose */
 163       error (0, 0, _("too many arguments"));
 164       usage (1);
 165     }
 166
 167   exit (0);
 168 }