[systemd-devel] [PATCH] machine-id: add --root option to operate on an alternate fs tree
Tom Gundersen
teg at jklm.no
Fri Mar 14 04:47:53 PDT 2014
On Fri, Mar 14, 2014 at 5:43 AM, Greg KH <gregkh at linuxfoundation.org> wrote:
> 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.
Thanks. Applied, with a little tweak: I used the _cleanup_free_
macros. Please have a look in case I messed something up.
Cheers,
Tom
> 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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