src/users.c

   1 /* GNU's users.
   2    Copyright (C) 1992-2001 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 #include "closeout.h"
  31
  32 /* The official name of this program (e.g., no `g' prefix).  */
  33 #define PROGRAM_NAME "users"
  34
  35 #define AUTHORS N_ ("Joseph Arceneaux and David MacKenzie")
  36
  37 /* The name this program was run with. */
  38 char *program_name;
  39
  40 static struct option const longopts[] =
  41 {
  42   {NULL, 0, NULL, 0}
  43 };
  44
  45 static int
  46 userid_compare (const void *v_a, const void *v_b)
  47 {
  48   char **a = (char **) v_a;
  49   char **b = (char **) v_b;
  50   return strcmp (*a, *b);
  51 }
  52
  53 static void
  54 list_entries_users (int n, const STRUCT_UTMP *this)
  55 {
  56   char **u;
  57   int i;
  58   int n_entries;
  59
  60   n_entries = 0;
  61   u = (char **) xmalloc (n * sizeof (u[0]));
  62   for (i = 0; i < n; i++)
  63     {
  64       if (UT_USER (this) [0]
  65 #ifdef USER_PROCESS
  66           && this->ut_type == USER_PROCESS
  67 #endif
  68           )
  69         {
  70           char *trimmed_name;
  71
  72           trimmed_name = extract_trimmed_name (this);
  73
  74           u[n_entries] = trimmed_name;
  75           ++n_entries;
  76         }
  77       this++;
  78     }
  79
  80   qsort (u, n_entries, sizeof (u[0]), userid_compare);
  81
  82   for (i = 0; i < n_entries; i++)
  83     {
  84       int c;
  85       fputs (u[i], stdout);
  86       c = (i < n_entries - 1 ? ' ' : '\n');
  87       putchar (c);
  88     }
  89
  90   for (i = 0; i < n_entries; i++)
  91     free (u[i]);
  92   free (u);
  93 }
  94
  95 /* Display a list of users on the system, according to utmp file FILENAME. */
  96
  97 static void
  98 users (const char *filename)
  99 {
 100   int n_users;
 101   STRUCT_UTMP *utmp_buf;
 102   int fail = read_utmp (filename, &n_users, &utmp_buf);
 103
 104   if (fail)
 105     error (1, errno, "%s", filename);
 106
 107   list_entries_users (n_users, utmp_buf);
 108 }
 109
 110 void
 111 usage (int status)
 112 {
 113   if (status != 0)
 114     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 115              program_name);
 116   else
 117     {
 118       printf (_("Usage: %s [OPTION]... [ FILE ]\n"), program_name);
 119       printf (_("\
 120 Output who is currently logged in according to FILE.\n\
 121 If FILE is not specified, use %s.  %s as FILE is common.\n\
 122 \n\
 123 "),
 124               UTMP_FILE, WTMP_FILE);
 125       fputs (HELP_OPTION_DESCRIPTION, stdout);
 126       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 127       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 128     }
 129   exit (status);
 130 }
 131
 132 int
 133 main (int argc, char **argv)
 134 {
 135   int optc, longind;
 136   program_name = argv[0];
 137   setlocale (LC_ALL, "");
 138   bindtextdomain (PACKAGE, LOCALEDIR);
 139   textdomain (PACKAGE);
 140
 141   atexit (close_stdout);
 142
 143   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
 144                       AUTHORS, usage);
 145
 146   while ((optc = getopt_long (argc, argv, "", longopts, &longind)) != -1)
 147     {
 148       switch (optc)
 149         {
 150         case 0:
 151           break;
 152
 153         default:
 154           usage (1);
 155         }
 156     }
 157
 158   switch (argc - optind)
 159     {
 160     case 0:                     /* users */
 161       users (UTMP_FILE);
 162       break;
 163
 164     case 1:                     /* users <utmp file> */
 165       users (argv[optind]);
 166       break;
 167
 168     default:                    /* lose */
 169       error (0, 0, _("too many arguments"));
 170       usage (1);
 171     }
 172
 173   exit (0);
 174 }