src/users.c

   1 /* GNU's users.
   2    Copyright (C) 1992-2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 "quote.h"
  30 #include "readutmp.h"
  31
  32 /* The official name of this program (e.g., no `g' prefix).  */
  33 #define PROGRAM_NAME "users"
  34
  35 #define AUTHORS "Joseph Arceneaux", "David MacKenzie"
  36
  37 /* The name this program was run with. */
  38 char *program_name;
  39
  40 static int
  41 userid_compare (const void *v_a, const void *v_b)
  42 {
  43   char **a = (char **) v_a;
  44   char **b = (char **) v_b;
  45   return strcmp (*a, *b);
  46 }
  47
  48 static void
  49 list_entries_users (size_t n, const STRUCT_UTMP *this)
  50 {
  51   char **u = xnmalloc (n, sizeof *u);
  52   size_t i;
  53   size_t n_entries = 0;
  54
  55   while (n--)
  56     {
  57       if (IS_USER_PROCESS (this))
  58         {
  59           char *trimmed_name;
  60
  61           trimmed_name = extract_trimmed_name (this);
  62
  63           u[n_entries] = trimmed_name;
  64           ++n_entries;
  65         }
  66       this++;
  67     }
  68
  69   qsort (u, n_entries, sizeof (u[0]), userid_compare);
  70
  71   for (i = 0; i < n_entries; i++)
  72     {
  73       char c = (i < n_entries - 1 ? ' ' : '\n');
  74       fputs (u[i], stdout);
  75       putchar (c);
  76     }
  77
  78   for (i = 0; i < n_entries; i++)
  79     free (u[i]);
  80   free (u);
  81 }
  82
  83 /* Display a list of users on the system, according to utmp file FILENAME.
  84    Use read_utmp OPTIONS to read FILENAME.  */
  85
  86 static void
  87 users (const char *filename, int options)
  88 {
  89   size_t n_users;
  90   STRUCT_UTMP *utmp_buf;
  91
  92   if (read_utmp (filename, &n_users, &utmp_buf, options) != 0)
  93     error (EXIT_FAILURE, errno, "%s", filename);
  94
  95   list_entries_users (n_users, utmp_buf);
  96
  97   free (utmp_buf);
  98 }
  99
 100 void
 101 usage (int status)
 102 {
 103   if (status != EXIT_SUCCESS)
 104     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 105              program_name);
 106   else
 107     {
 108       printf (_("Usage: %s [OPTION]... [ FILE ]\n"), program_name);
 109       printf (_("\
 110 Output who is currently logged in according to FILE.\n\
 111 If FILE is not specified, use %s.  %s as FILE is common.\n\
 112 \n\
 113 "),
 114               UTMP_FILE, WTMP_FILE);
 115       fputs (HELP_OPTION_DESCRIPTION, stdout);
 116       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 117       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 118     }
 119   exit (status);
 120 }
 121
 122 int
 123 main (int argc, char **argv)
 124 {
 125   initialize_main (&argc, &argv);
 126   program_name = argv[0];
 127   setlocale (LC_ALL, "");
 128   bindtextdomain (PACKAGE, LOCALEDIR);
 129   textdomain (PACKAGE);
 130
 131   atexit (close_stdout);
 132
 133   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
 134                       usage, AUTHORS, (char const *) NULL);
 135   if (getopt_long (argc, argv, "", NULL, NULL) != -1)
 136     usage (EXIT_FAILURE);
 137
 138   switch (argc - optind)
 139     {
 140     case 0:                     /* users */
 141       users (UTMP_FILE, READ_UTMP_CHECK_PIDS);
 142       break;
 143
 144     case 1:                     /* users <utmp file> */
 145       users (argv[optind], 0);
 146       break;
 147
 148     default:                    /* lose */
 149       error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
 150       usage (EXIT_FAILURE);
 151     }
 152
 153   exit (EXIT_SUCCESS);
 154 }