1  /* print the hexadecimal identifier for the current host
       2  
       3     Copyright (C) 1997-2023 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 <https://www.gnu.org/licenses/>.  */
      17  
      18  /* Written by Jim Meyering.  */
      19  
      20  #include <config.h>
      21  #include <stdio.h>
      22  #include <sys/types.h>
      23  
      24  #include "system.h"
      25  #include "long-options.h"
      26  #include "quote.h"
      27  
      28  /* The official name of this program (e.g., no 'g' prefix).  */
      29  #define PROGRAM_NAME "hostid"
      30  
      31  #define AUTHORS proper_name ("Jim Meyering")
      32  
      33  void
      34  usage (int status)
      35  {
      36    if (status != EXIT_SUCCESS)
      37      emit_try_help ();
      38    else
      39      {
      40        printf (_("\
      41  Usage: %s [OPTION]\n\
      42  Print the numeric identifier (in hexadecimal) for the current host.\n\
      43  \n\
      44  "), program_name);
      45        fputs (HELP_OPTION_DESCRIPTION, stdout);
      46        fputs (VERSION_OPTION_DESCRIPTION, stdout);
      47        emit_ancillary_info (PROGRAM_NAME);
      48      }
      49    exit (status);
      50  }
      51  
      52  int
      53  main (int argc, char **argv)
      54  {
      55    unsigned int id;
      56  
      57    initialize_main (&argc, &argv);
      58    set_program_name (argv[0]);
      59    setlocale (LC_ALL, "");
      60    bindtextdomain (PACKAGE, LOCALEDIR);
      61    textdomain (PACKAGE);
      62  
      63    atexit (close_stdout);
      64  
      65    parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
      66                                     Version, true, usage, AUTHORS,
      67                                     (char const *) nullptr);
      68  
      69    if (optind < argc)
      70      {
      71        error (0, 0, _("extra operand %s"), quote (argv[optind]));
      72        usage (EXIT_FAILURE);
      73      }
      74  
      75    id = gethostid ();
      76  
      77    /* POSIX says gethostid returns a "32-bit identifier" but is silent
      78       whether it's sign-extended.  Turn off any sign-extension.  This
      79       is a no-op unless unsigned int is wider than 32 bits.  */
      80    id &= 0xffffffff;
      81  
      82    printf ("%08x\n", id);
      83  
      84    return EXIT_SUCCESS;
      85  }