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git.ipfire.org Git - thirdparty/systemd.git/blob - src/machine-id-setup.c
1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
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 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
28 #include <sys/mount.h>
30 #include "machine-id-setup.h"
35 static int generate(char id
[34]) {
43 /* First, try reading the D-Bus machine id, unless it is a symlink */
44 if ((fd
= open("/var/lib/dbus/machine-id", O_RDONLY
|O_CLOEXEC
|O_NOCTTY
|O_NOFOLLOW
)) >= 0) {
46 k
= loop_read(fd
, id
, 33, false);
47 close_nointr_nofail(fd
);
53 log_info("Initializing machine ID from D-Bus machine ID.");
58 /* If that didn't work, generate a random machine id */
59 if ((fd
= open("/dev/urandom", O_RDONLY
|O_CLOEXEC
|O_NOCTTY
)) < 0) {
60 log_error("Failed to open /dev/urandom: %m");
64 k
= loop_read(fd
, buf
, sizeof(buf
), false);
65 close_nointr_nofail(fd
);
67 if (k
!= sizeof(buf
)) {
68 log_error("Failed to read /dev/urandom: %s", strerror(k
< 0 ? -k
: EIO
));
69 return k
< 0 ? (int) k
: -EIO
;
72 for (p
= buf
, q
= id
; p
< buf
+ sizeof(buf
); p
++, q
+= 2) {
73 q
[0] = hexchar(*p
>> 4);
74 q
[1] = hexchar(*p
& 15);
80 log_info("Initializing machine ID from random generator.");
85 int machine_id_setup(void) {
89 char id
[34]; /* 32 + \n + \0 */
94 /* We create this 0444, to indicate that this isn't really
95 * something you should ever modify. Of course, since the file
96 * will be owned by root it doesn't matter much, but maybe
99 if ((fd
= open("/etc/machine-id", O_RDWR
|O_CREAT
|O_CLOEXEC
|O_NOCTTY
, 0444)) >= 0)
102 if ((fd
= open("/etc/machine-id", O_RDONLY
|O_CLOEXEC
|O_NOCTTY
)) < 0) {
104 log_error("Cannot open /etc/machine-id: %m");
113 if (fstat(fd
, &st
) < 0) {
114 log_error("fstat() failed: %m");
119 if (S_ISREG(st
.st_mode
)) {
120 if (loop_read(fd
, id
, 32, false) >= 32) {
126 /* Hmm, so, the id currently stored is not useful, then let's
129 if ((r
= generate(id
)) < 0)
132 if (S_ISREG(st
.st_mode
) && writable
) {
133 lseek(fd
, 0, SEEK_SET
);
135 if (loop_write(fd
, id
, 33, false) == 33) {
141 close_nointr_nofail(fd
);
144 /* Hmm, we couldn't write it? So let's write it to
145 * /run/systemd/machine-id as a replacement */
147 mkdir_p("/run/systemd", 0755);
149 if ((r
= write_one_line_file("/run/systemd/machine-id", id
)) < 0) {
150 log_error("Cannot write /run/systemd/machine-id: %s", strerror(-r
));
152 unlink("/run/systemd/machine-id");
156 /* And now, let's mount it over */
157 r
= mount("/run/systemd/machine-id", "/etc/machine-id", "bind", MS_BIND
|MS_RDONLY
, NULL
) < 0 ? -errno
: 0;
158 unlink("/run/systemd/machine-id");
161 log_error("Failed to mount /etc/machine-id: %s", strerror(-r
));
163 log_info("Installed transient /etc/machine-id file.");
168 close_nointr_nofail(fd
);