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machine-id: add --root option to operate on an alternate fs tree

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This makes it possible to initialize the /etc/machine-id file on an
arbitrary filesystem hierarchy.  This helps systems that wish to run
this at image creation time in a subdirectory, or from initramfs before
pivot-root is called.

[tomegun: converted to using _cleanup_free_ macros]
This commit is contained in:
Greg KH 2014-03-14 04:43:04 +00:00 committed by Tom Gundersen
parent 06f021a804
commit 92f2f92edc
5 changed files with 50 additions and 21 deletions
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8
man/systemd-machine-id-setup.xml
View File

@ -96,6 +96,14 @@
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--root=ROOT</option></term>
<listitem><para>Takes a directory path
as an argument. All paths will be
prefixed with the given alternate ROOT
path, including config search paths.
</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>

44
src/core/machine-id-setup.c
View File

@ -59,18 +59,22 @@ static int shorten_uuid(char destination[36], const char *source) {
return -EINVAL;
}
static int generate(char id[34]) {
static int generate(char id[34], const char *root) {
int fd, r;
unsigned char *p;
sd_id128_t buf;
char *q;
ssize_t k;
const char *vm_id;
_cleanup_free_ char *dbus_machine_id = NULL;
assert(id);
if (asprintf(&dbus_machine_id, "%s/var/lib/dbus/machine-id", root) < 0)
return log_oom();
/* First, try reading the D-Bus machine id, unless it is a symlink */
fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd >= 0) {
k = loop_read(fd, id, 33, false);
close_nointr_nofail(fd);
@ -150,12 +154,20 @@ static int generate(char id[34]) {
return 0;
}
int machine_id_setup(void) {
int machine_id_setup(const char *root) {
_cleanup_close_ int fd = -1;
int r;
bool writable = false;
struct stat st;
char id[34]; /* 32 + \n + \0 */
_cleanup_free_ char *etc_machine_id = NULL;
_cleanup_free_ char *run_machine_id = NULL;
if (asprintf(&etc_machine_id, "%s/etc/machine-id", root) < 0)
return log_oom();
if (asprintf(&run_machine_id, "%s/run/machine-id", root) < 0)
return log_oom();
RUN_WITH_UMASK(0000) {
/* We create this 0444, to indicate that this isn't really
@ -163,13 +175,13 @@ int machine_id_setup(void) {
* will be owned by root it doesn't matter much, but maybe
* people look. */
fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
if (fd >= 0)
writable = true;
else {
fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0) {
log_error("Cannot open /etc/machine-id: %m");
log_error("Cannot open %s: %m", etc_machine_id);
return -errno;
}
@ -193,7 +205,7 @@ int machine_id_setup(void) {
/* Hmm, so, the id currently stored is not useful, then let's
* generate one */
r = generate(id);
r = generate(id, root);
if (r < 0)
return r;
@ -211,27 +223,27 @@ int machine_id_setup(void) {
* /run/machine-id as a replacement */
RUN_WITH_UMASK(0022) {
r = write_string_file("/run/machine-id", id);
r = write_string_file(run_machine_id, id);
}
if (r < 0) {
log_error("Cannot write /run/machine-id: %s", strerror(-r));
unlink("/run/machine-id");
log_error("Cannot write %s: %s", run_machine_id, strerror(-r));
unlink(run_machine_id);
return r;
}
/* And now, let's mount it over */
r = mount("/run/machine-id", "/etc/machine-id", NULL, MS_BIND, NULL);
r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL);
if (r < 0) {
log_error("Failed to mount /etc/machine-id: %m");
unlink_noerrno("/run/machine-id");
log_error("Failed to mount %s: %m", etc_machine_id);
unlink_noerrno(run_machine_id);
return -errno;
}
log_info("Installed transient /etc/machine-id file.");
log_info("Installed transient %s file.", etc_machine_id);
/* Mark the mount read-only */
if (mount(NULL, "/etc/machine-id", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
log_warning("Failed to make transient /etc/machine-id read-only: %m");
if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
log_warning("Failed to make transient %s read-only: %m", etc_machine_id);
return 0;
}

2
src/core/machine-id-setup.h
View File

@ -21,4 +21,4 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
int machine_id_setup(void);
int machine_id_setup(const char *root);

2
src/core/main.c
View File

@ -1582,7 +1582,7 @@ int main(int argc, char *argv[]) {
kmod_setup();
#endif
hostname_setup();
machine_id_setup();
machine_id_setup("");
loopback_setup();
test_mtab();

15
src/machine-id-setup/machine-id-setup-main.c
View File

@ -29,12 +29,15 @@
#include "log.h"
#include "build.h"
static const char *arg_root = "";
static int help(void) {
printf("%s [OPTIONS...]\n\n"
"Initialize /etc/machine-id from a random source.\n\n"
" -h --help Show this help\n"
" --version Show package version\n",
" --version Show package version\n"
" --root Filesystem root\n",
program_invocation_short_name);
return 0;
@ -43,12 +46,14 @@ static int help(void) {
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_VERSION = 0x100
ARG_VERSION = 0x100,
ARG_ROOT,
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "root", required_argument, NULL, ARG_ROOT },
{}
};
@ -69,6 +74,10 @@ static int parse_argv(int argc, char *argv[]) {
puts(SYSTEMD_FEATURES);
return 0;
case ARG_ROOT:
arg_root = optarg;
break;
case '?':
return -EINVAL;
@ -95,5 +104,5 @@ int main(int argc, char *argv[]) {
if (r <= 0)
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
return machine_id_setup() < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
return machine_id_setup(arg_root) < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}