src/hostid.c

   1 /* print the hexadecimal identifier for the current host
   2
   3    Copyright (C) 1997, 1999-2004, 2007-2011 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Jim Meyering.  */
  19
  20 #include <config.h>
  21 #include <getopt.h>
  22 #include <stdio.h>
  23 #include <sys/types.h>
  24
  25 #include "system.h"
  26 #include "long-options.h"
  27 #include "error.h"
  28 #include "quote.h"
  29
  30 /* The official name of this program (e.g., no `g' prefix).  */
  31 #define PROGRAM_NAME "hostid"
  32
  33 #define AUTHORS proper_name ("Jim Meyering")
  34
  35 void
  36 usage (int status)
  37 {
  38   if (status != EXIT_SUCCESS)
  39     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  40              program_name);
  41   else
  42     {
  43       printf (_("\
  44 Usage: %s [OPTION]\n\
  45 Print the numeric identifier (in hexadecimal) for the current host.\n\
  46 \n\
  47 "), program_name);
  48       fputs (HELP_OPTION_DESCRIPTION, stdout);
  49       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  50       emit_ancillary_info ();
  51     }
  52   exit (status);
  53 }
  54
  55 int
  56 main (int argc, char **argv)
  57 {
  58   unsigned int id;
  59
  60   initialize_main (&argc, &argv);
  61   set_program_name (argv[0]);
  62   setlocale (LC_ALL, "");
  63   bindtextdomain (PACKAGE, LOCALEDIR);
  64   textdomain (PACKAGE);
  65
  66   atexit (close_stdout);
  67
  68   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, Version,
  69                       usage, AUTHORS, (char const *) NULL);
  70   if (getopt_long (argc, argv, "", NULL, NULL) != -1)
  71     usage (EXIT_FAILURE);
  72
  73   if (optind < argc)
  74     {
  75       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  76       usage (EXIT_FAILURE);
  77     }
  78
  79   id = gethostid ();
  80
  81   /* POSIX says gethostid returns a "32-bit identifier" but is silent
  82      whether it's sign-extended.  Turn off any sign-extension.  This
  83      is a no-op unless unsigned int is wider than 32 bits.  */
  84   id &= 0xffffffff;
  85
  86   printf ("%08x\n", id);
  87
  88   exit (EXIT_SUCCESS);
  89 }