1  /* hostname - set or print the name of current host system
       2     Copyright (C) 1994-2023 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 3 of the License, or
       7     (at your option) 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, see <https://www.gnu.org/licenses/>.  */
      16  
      17  /* Written by Jim Meyering.  */
      18  
      19  #include <config.h>
      20  #include <stdio.h>
      21  #include <sys/types.h>
      22  
      23  #include "system.h"
      24  #include "long-options.h"
      25  #include "quote.h"
      26  #include "xgethostname.h"
      27  
      28  /* The official name of this program (e.g., no 'g' prefix).  */
      29  #define PROGRAM_NAME "hostname"
      30  
      31  #define AUTHORS proper_name ("Jim Meyering")
      32  
      33  #ifndef HAVE_SETHOSTNAME
      34  # if defined HAVE_SYSINFO && defined HAVE_SYS_SYSTEMINFO_H
      35  #  include <sys/systeminfo.h>
      36  # endif
      37  
      38  static int
      39  sethostname (char const *name, size_t namelen)
      40  {
      41  # if defined HAVE_SYSINFO && defined HAVE_SYS_SYSTEMINFO_H
      42    /* Using sysinfo() is the SVR4 mechanism to set a hostname. */
      43    return (sysinfo (SI_SET_HOSTNAME, name, namelen) < 0 ? -1 : 0);
      44  # else
      45    errno = ENOTSUP;
      46    return -1;
      47  # endif
      48  }
      49  #endif
      50  
      51  void
      52  usage (int status)
      53  {
      54    if (status != EXIT_SUCCESS)
      55      emit_try_help ();
      56    else
      57      {
      58        printf (_("\
      59  Usage: %s [NAME]\n\
      60    or:  %s OPTION\n\
      61  Print or set the hostname of the current system.\n\
      62  \n\
      63  "),
      64               program_name, program_name);
      65        fputs (HELP_OPTION_DESCRIPTION, stdout);
      66        fputs (VERSION_OPTION_DESCRIPTION, stdout);
      67        emit_ancillary_info (PROGRAM_NAME);
      68      }
      69    exit (status);
      70  }
      71  
      72  int
      73  main (int argc, char **argv)
      74  {
      75    char *hostname;
      76  
      77    initialize_main (&argc, &argv);
      78    set_program_name (argv[0]);
      79    setlocale (LC_ALL, "");
      80    bindtextdomain (PACKAGE, LOCALEDIR);
      81    textdomain (PACKAGE);
      82  
      83    atexit (close_stdout);
      84  
      85    parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
      86                                     Version, true, usage, AUTHORS,
      87                                     (char const *) nullptr);
      88  
      89    if (optind + 1 < argc)
      90       {
      91         error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
      92         usage (EXIT_FAILURE);
      93       }
      94  
      95    if (optind + 1 == argc)
      96      {
      97        /* Set hostname to operand.  */
      98        char const *name = argv[optind];
      99        if (sethostname (name, strlen (name)) != 0)
     100          error (EXIT_FAILURE, errno, _("cannot set name to %s"),
     101                 quote (name));
     102      }
     103    else
     104      {
     105        hostname = xgethostname ();
     106        if (hostname == nullptr)
     107          error (EXIT_FAILURE, errno, _("cannot determine hostname"));
     108        puts (hostname);
     109      }
     110  
     111    main_exit (EXIT_SUCCESS);
     112  }