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authorGreg KH <gregkh@linuxfoundation.org>2014-03-14 04:43:04 +0000
committerTom Gundersen <teg@jklm.no>2014-03-14 12:44:17 +0100
commit92f2f92edcad46ce4098ee26504edca0a1dad68e (patch)
tree9ad2337000ed976c22f42adf19595800671824a2 /src/core/machine-id-setup.c
parent06f021a8048583d66202e3ac5cd0a12386d33ac2 (diff)
machine-id: add --root option to operate on an alternate fs tree
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]
Diffstat (limited to 'src/core/machine-id-setup.c')
-rw-r--r--src/core/machine-id-setup.c44
1 files changed, 28 insertions, 16 deletions
diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c
index 1b55da7e56..f3b1b318e1 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]) {
+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;
}