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 "die.h"
  26 #include "error.h"
  27 #include "quote.h"
  28 #include "xgethostname.h"
  29
  30 /* The official name of this program (e.g., no 'g' prefix).  */
  31 #define PROGRAM_NAME "hostname"
  32
  33 #define AUTHORS proper_name ("Jim Meyering")
  34
  35 #ifndef HAVE_SETHOSTNAME
  36 # if defined HAVE_SYSINFO && defined HAVE_SYS_SYSTEMINFO_H
  37 #  include <sys/systeminfo.h>
  38 # endif
  39
  40 static int
  41 sethostname (char const *name, size_t namelen)
  42 {
  43 # if defined HAVE_SYSINFO && defined HAVE_SYS_SYSTEMINFO_H
  44   /* Using sysinfo() is the SVR4 mechanism to set a hostname. */
  45   return (sysinfo (SI_SET_HOSTNAME, name, namelen) < 0 ? -1 : 0);
  46 # else
  47   errno = ENOTSUP;
  48   return -1;
  49 # endif
  50 }
  51 #endif
  52
  53 void
  54 usage (int status)
  55 {
  56   if (status != EXIT_SUCCESS)
  57     emit_try_help ();
  58   else
  59     {
  60       printf (_("\
  61 Usage: %s [NAME]\n\
  62   or:  %s OPTION\n\
  63 Print or set the hostname of the current system.\n\
  64 \n\
  65 "),
  66              program_name, program_name);
  67       fputs (HELP_OPTION_DESCRIPTION, stdout);
  68       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  69       emit_ancillary_info (PROGRAM_NAME);
  70     }
  71   exit (status);
  72 }
  73
  74 int
  75 main (int argc, char **argv)
  76 {
  77   char *hostname;
  78
  79   initialize_main (&argc, &argv);
  80   set_program_name (argv[0]);
  81   setlocale (LC_ALL, "");
  82   bindtextdomain (PACKAGE, LOCALEDIR);
  83   textdomain (PACKAGE);
  84
  85   atexit (close_stdout);
  86
  87   parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
  88                                    Version, true, usage, AUTHORS,
  89                                    (char const *) NULL);
  90
  91   if (optind + 1 < argc)
  92      {
  93        error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
  94        usage (EXIT_FAILURE);
  95      }
  96
  97   if (optind + 1 == argc)
  98     {
  99       /* Set hostname to operand.  */
 100       char const *name = argv[optind];
 101       if (sethostname (name, strlen (name)) != 0)
 102         die (EXIT_FAILURE, errno, _("cannot set name to %s"),
 103              quote (name));
 104     }
 105   else
 106     {
 107       hostname = xgethostname ();
 108       if (hostname == NULL)
 109         die (EXIT_FAILURE, errno, _("cannot determine hostname"));
 110       puts (hostname);
 111     }
 112
 113   main_exit (EXIT_SUCCESS);
 114 }