src/hostid.c

   1 /* print the hexadecimal identifier for the current host
   2
   3    Copyright (C) 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2007-2009 Free
   4    Software Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* Written by Jim Meyering.  */
  20
  21 #include <config.h>
  22 #include <getopt.h>
  23 #include <stdio.h>
  24 #include <sys/types.h>
  25
  26 #include "system.h"
  27 #include "long-options.h"
  28 #include "error.h"
  29 #include "quote.h"
  30
  31 /* The official name of this program (e.g., no `g' prefix).  */
  32 #define PROGRAM_NAME "hostid"
  33
  34 #define AUTHORS proper_name ("Jim Meyering")
  35
  36 void
  37 usage (int status)
  38 {
  39   if (status != EXIT_SUCCESS)
  40     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  41              program_name);
  42   else
  43     {
  44       printf (_("\
  45 Usage: %s [OPTION]\n\
  46 Print the numeric identifier (in hexadecimal) for the current host.\n\
  47 \n\
  48 "), program_name);
  49       fputs (HELP_OPTION_DESCRIPTION, stdout);
  50       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  51       emit_ancillary_info ();
  52     }
  53   exit (status);
  54 }
  55
  56 int
  57 main (int argc, char **argv)
  58 {
  59   unsigned int id;
  60
  61   initialize_main (&argc, &argv);
  62   set_program_name (argv[0]);
  63   setlocale (LC_ALL, "");
  64   bindtextdomain (PACKAGE, LOCALEDIR);
  65   textdomain (PACKAGE);
  66
  67   atexit (close_stdout);
  68
  69   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, Version,
  70                       usage, AUTHORS, (char const *) NULL);
  71   if (getopt_long (argc, argv, "", NULL, NULL) != -1)
  72     usage (EXIT_FAILURE);
  73
  74   if (optind < argc)
  75     {
  76       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  77       usage (EXIT_FAILURE);
  78     }
  79
  80   id = gethostid ();
  81
  82   /* POSIX says gethostid returns a "32-bit identifier" but is silent
  83      whether it's sign-extended.  Turn off any sign-extension.  This
  84      is a no-op unless unsigned int is wider than 32 bits.  */
  85   id &= 0xffffffff;
  86
  87   printf ("%08x\n", id);
  88
  89   exit (EXIT_SUCCESS);
  90 }