[systemd-devel] [PATCH] machine-id: add --root option to operate on an alternate fs tree
Greg KH
gregkh at linuxfoundation.org
Thu Mar 13 21:43:04 PDT 2014
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.
diff --git a/man/systemd-machine-id-setup.xml b/man/systemd-machine-id-setup.xml
index 5c34b345d012..b879b40b997d 100644
--- a/man/systemd-machine-id-setup.xml
+++ b/man/systemd-machine-id-setup.xml
@@ -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>
diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c
index 1b55da7e56b8..7d52b468a11a 100644
--- a/src/core/machine-id-setup.c
+++ b/src/core/machine-id-setup.c
@@ -59,18 +59,22 @@ static int shorten_uuid(char destination[36], const char *source) {
return -EINVAL;
}
-static int generate(char id[34]) {
- int fd, r;
+static int generate(char id[34], const char *root) {
+ int fd, r = 0;
unsigned char *p;
sd_id128_t buf;
char *q;
ssize_t k;
const char *vm_id;
+ char *dbus_machine_id;
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);
@@ -83,7 +87,7 @@ static int generate(char id[34]) {
id[33] = 0;
log_info("Initializing machine ID from D-Bus machine ID.");
- return 0;
+ goto finish;
}
}
}
@@ -105,7 +109,8 @@ static int generate(char id[34]) {
r = shorten_uuid(id, uuid);
if (r >= 0) {
log_info("Initializing machine ID from KVM UUID.");
- return 0;
+ r = 0;
+ goto finish;
}
}
}
@@ -124,7 +129,8 @@ static int generate(char id[34]) {
r = shorten_uuid(id, e);
if (r >= 0) {
log_info("Initializing machine ID from container UUID.");
- return 0;
+ r = 0;
+ goto finish;
}
}
}
@@ -134,7 +140,7 @@ static int generate(char id[34]) {
r = sd_id128_randomize(&buf);
if (r < 0) {
log_error("Failed to open /dev/urandom: %s", strerror(-r));
- return r;
+ goto finish;
}
for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
@@ -147,15 +153,27 @@ static int generate(char id[34]) {
log_info("Initializing machine ID from random generator.");
- return 0;
+finish:
+ free(dbus_machine_id);
+ return r;
}
-int machine_id_setup(void) {
+int machine_id_setup(const char *root) {
_cleanup_close_ int fd = -1;
- int r;
+ int r = 0;
bool writable = false;
struct stat st;
char id[34]; /* 32 + \n + \0 */
+ char *etc_machine_id = NULL;
+ 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) {
+ r = log_oom();
+ goto finish;
+ }
RUN_WITH_UMASK(0000) {
/* We create this 0444, to indicate that this isn't really
@@ -163,14 +181,15 @@ 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");
- return -errno;
+ log_error("Cannot open %s: %m", etc_machine_id);
+ r = -errno;
+ goto finish;
}
writable = false;
@@ -179,7 +198,8 @@ int machine_id_setup(void) {
if (fstat(fd, &st) < 0) {
log_error("fstat() failed: %m");
- return -errno;
+ r = -errno;
+ goto finish;
}
if (S_ISREG(st.st_mode))
@@ -187,21 +207,21 @@ int machine_id_setup(void) {
id[32] = 0;
if (id128_is_valid(id))
- return 0;
+ goto finish;
}
/* 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;
+ goto finish;
if (S_ISREG(st.st_mode) && writable) {
lseek(fd, 0, SEEK_SET);
if (loop_write(fd, id, 33, false) == 33)
- return 0;
+ goto finish;
}
close_nointr_nofail(fd);
@@ -211,27 +231,31 @@ 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");
- return r;
+ log_error("Cannot write %s: %s", run_machine_id, strerror(-r));
+ unlink(run_machine_id);
+ goto finish;
}
/* 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");
- return -errno;
+ log_error("Failed to mount %s: %m", etc_machine_id);
+ unlink_noerrno(run_machine_id);
+ r = -errno;
+ goto finish;
}
- 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;
+finish:
+ free(etc_machine_id);
+ free(run_machine_id);
+ return r;
}
diff --git a/src/core/machine-id-setup.h b/src/core/machine-id-setup.h
index b9e6b4d674a6..b0583eefc8fe 100644
--- a/src/core/machine-id-setup.h
+++ b/src/core/machine-id-setup.h
@@ -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);
diff --git a/src/core/main.c b/src/core/main.c
index f1b06d88803e..cc876efa9c2c 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -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();
diff --git a/src/machine-id-setup/machine-id-setup-main.c b/src/machine-id-setup/machine-id-setup-main.c
index 84af925f517e..a67d436dbd7c 100644
--- a/src/machine-id-setup/machine-id-setup-main.c
+++ b/src/machine-id-setup/machine-id-setup-main.c
@@ -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;
}
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