src/hostname.c

   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 }