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
usage(int status)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
main(int argc,char ** argv)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 }
86