src/users.c

   1 /* GNU's users.
   2    Copyright (C) 1992-2003 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 <sys/types.h>
  25 #include "system.h"
  26
  27 #include "error.h"
  28 #include "long-options.h"
  29 #include "readutmp.h"
  30
  31 /* The official name of this program (e.g., no `g' prefix).  */
  32 #define PROGRAM_NAME "users"
  33
  34 #define AUTHORS "Joseph Arceneaux", "David MacKenzie"
  35
  36 /* The name this program was run with. */
  37 char *program_name;
  38
  39 static struct option const longopts[] =
  40 {
  41   {NULL, 0, NULL, 0}
  42 };
  43
  44 static int
  45 userid_compare (const void *v_a, const void *v_b)
  46 {
  47   char **a = (char **) v_a;
  48   char **b = (char **) v_b;
  49   return strcmp (*a, *b);
  50 }
  51
  52 static void
  53 list_entries_users (int n, const STRUCT_UTMP *this)
  54 {
  55   char **u;
  56   int i;
  57   int n_entries;
  58
  59   n_entries = 0;
  60   u = xmalloc (n * sizeof (u[0]));
  61   for (i = 0; i < n; i++)
  62     {
  63       if (UT_USER (this) [0]
  64 #ifdef USER_PROCESS
  65           && this->ut_type == USER_PROCESS
  66 #endif
  67           )
  68         {
  69           char *trimmed_name;
  70
  71           trimmed_name = extract_trimmed_name (this);
  72
  73           u[n_entries] = trimmed_name;
  74           ++n_entries;
  75         }
  76       this++;
  77     }
  78
  79   qsort (u, n_entries, sizeof (u[0]), userid_compare);
  80
  81   for (i = 0; i < n_entries; i++)
  82     {
  83       int c;
  84       fputs (u[i], stdout);
  85       c = (i < n_entries - 1 ? ' ' : '\n');
  86       putchar (c);
  87     }
  88
  89   for (i = 0; i < n_entries; i++)
  90     free (u[i]);
  91   free (u);
  92 }
  93
  94 /* Display a list of users on the system, according to utmp file FILENAME. */
  95
  96 static void
  97 users (const char *filename)
  98 {
  99   int n_users;
 100   STRUCT_UTMP *utmp_buf;
 101   int fail = read_utmp (filename, &n_users, &utmp_buf);
 102
 103   if (fail)
 104     error (EXIT_FAILURE, errno, "%s", filename);
 105
 106   list_entries_users (n_users, utmp_buf);
 107
 108   free (utmp_buf);
 109 }
 110
 111 void
 112 usage (int status)
 113 {
 114   if (status != 0)
 115     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 116              program_name);
 117   else
 118     {
 119       printf (_("Usage: %s [OPTION]... [ FILE ]\n"), program_name);
 120       printf (_("\
 121 Output who is currently logged in according to FILE.\n\
 122 If FILE is not specified, use %s.  %s as FILE is common.\n\
 123 \n\
 124 "),
 125               UTMP_FILE, WTMP_FILE);
 126       fputs (HELP_OPTION_DESCRIPTION, stdout);
 127       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 128       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 129     }
 130   exit (status);
 131 }
 132
 133 int
 134 main (int argc, char **argv)
 135 {
 136   int optc, longind;
 137   initialize_main (&argc, &argv);
 138   program_name = argv[0];
 139   setlocale (LC_ALL, "");
 140   bindtextdomain (PACKAGE, LOCALEDIR);
 141   textdomain (PACKAGE);
 142
 143   atexit (close_stdout);
 144
 145   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
 146                       usage, AUTHORS, (char const *) NULL);
 147
 148   while ((optc = getopt_long (argc, argv, "", longopts, &longind)) != -1)
 149     {
 150       switch (optc)
 151         {
 152         case 0:
 153           break;
 154
 155         default:
 156           usage (EXIT_FAILURE);
 157         }
 158     }
 159
 160   switch (argc - optind)
 161     {
 162     case 0:                     /* users */
 163       users (UTMP_FILE);
 164       break;
 165
 166     case 1:                     /* users <utmp file> */
 167       users (argv[optind]);
 168       break;
 169
 170     default:                    /* lose */
 171       error (0, 0, _("too many arguments"));
 172       usage (EXIT_FAILURE);
 173     }
 174
 175   exit (EXIT_SUCCESS);
 176 }