src/core/hostname-setup.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <errno.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27
  28 #include "hostname-setup.h"
  29 #include "macro.h"
  30 #include "util.h"
  31 #include "log.h"
  32 #include "fileio.h"
  33
  34 static int read_and_strip_hostname(const char *path, char **hn) {
  35         char *s;
  36         int r;
  37
  38         assert(path);
  39         assert(hn);
  40
  41         r = read_one_line_file(path, &s);
  42         if (r < 0)
  43                 return r;
  44
  45         hostname_cleanup(s, false);
  46
  47         if (isempty(s)) {
  48                 free(s);
  49                 return -ENOENT;
  50         }
  51
  52         *hn = s;
  53         return 0;
  54 }
  55
  56 int hostname_setup(void) {
  57         int r;
  58         _cleanup_free_ char *b = NULL;
  59         const char *hn;
  60         bool enoent = false;
  61
  62         r = read_and_strip_hostname("/etc/hostname", &b);
  63         if (r < 0) {
  64                 if (r == -ENOENT)
  65                         enoent = true;
  66                 else
  67                         log_warning_errno(r, "Failed to read configured hostname: %m");
  68
  69                 hn = NULL;
  70         } else
  71                 hn = b;
  72
  73         if (isempty(hn)) {
  74                 /* Don't override the hostname if it is already set
  75                  * and not explicitly configured */
  76                 if (hostname_is_set())
  77                         return 0;
  78
  79                 if (enoent)
  80                         log_info("No hostname configured.");
  81
  82                 hn = "localhost";
  83         }
  84
  85         if (sethostname_idempotent(hn) < 0) {
  86                 log_warning_errno(errno, "Failed to set hostname to <%s>: %m", hn);
  87                 return -errno;
  88         }
  89
  90         log_info("Set hostname to <%s>.", hn);
  91         return 0;
  92 }