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authorLennart Poettering <lennart@poettering.net>2014-12-12 16:59:15 +0100
committerLennart Poettering <lennart@poettering.net>2014-12-12 17:30:25 +0100
commitc4e34a612c81266773cf8358cb38a43d2e43474e (patch)
tree30365df7de959342130bd88d1ce6d6be7c32d73d
parentdf9a75e480ecbfe230589a7c1e8e0bb790ee0595 (diff)
nspawn: allow spawning ephemeral nspawn containers based on the root file system of the OS
This works now: # systemd-nspawn -xb -D / -M foobar Which boots up an ephemeral container, based on the host's root file system. Or in other words: you can now run the very same host OS you booted your system with also in a container, on top of it, without having it interfere. Great for testing whether the init system you are hacking on still boots without reboot the system!
-rw-r--r--src/nspawn/nspawn.c20
-rw-r--r--src/shared/util.c52
-rw-r--r--src/shared/util.h1
3 files changed, 68 insertions, 5 deletions
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index f6f20abdaf..651a45126b 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -2942,8 +2942,8 @@ int main(int argc, char *argv[]) {
if (arg_directory) {
assert(!arg_image);
- if (path_equal(arg_directory, "/")) {
- log_error("Spawning container on root directory not supported.");
+ if (path_equal(arg_directory, "/") && !arg_ephemeral) {
+ log_error("Spawning container on root directory is not supported. Consider using --ephemeral.");
r = -EINVAL;
goto finish;
}
@@ -2964,7 +2964,21 @@ int main(int argc, char *argv[]) {
} else if (arg_ephemeral) {
char *np;
- r = tempfn_random(arg_directory, &np);
+ /* If the specified path is a mount point we
+ * generate the new snapshot immediately
+ * inside it under a random name. However if
+ * the specified is not a mount point we
+ * create the new snapshot in the parent
+ * directory, just next to it. */
+ r = path_is_mount_point(arg_directory, false);
+ if (r < 0) {
+ log_error_errno(r, "Failed to determine whether directory %s is mount point: %m", arg_directory);
+ goto finish;
+ }
+ if (r > 0)
+ r = tempfn_random_child(arg_directory, &np);
+ else
+ r = tempfn_random(arg_directory, &np);
if (r < 0) {
log_error_errno(r, "Failed to generate name for snapshot: %m");
goto finish;
diff --git a/src/shared/util.c b/src/shared/util.c
index 254b5637ae..ee95a4b6f7 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -6977,6 +6977,14 @@ int tempfn_xxxxxx(const char *p, char **ret) {
assert(p);
assert(ret);
+ /*
+ * Turns this:
+ * /foo/bar/waldo
+ *
+ * Into this:
+ * /foo/bar/.waldoXXXXXX
+ */
+
fn = basename(p);
if (!filename_is_valid(fn))
return -EINVAL;
@@ -6987,7 +6995,7 @@ int tempfn_xxxxxx(const char *p, char **ret) {
strcpy(stpcpy(stpcpy(mempcpy(t, p, fn - p), "."), fn), "XXXXXX");
- *ret = t;
+ *ret = path_kill_slashes(t);
return 0;
}
@@ -7000,6 +7008,14 @@ int tempfn_random(const char *p, char **ret) {
assert(p);
assert(ret);
+ /*
+ * Turns this:
+ * /foo/bar/waldo
+ *
+ * Into this:
+ * /foo/bar/.waldobaa2a261115984a9
+ */
+
fn = basename(p);
if (!filename_is_valid(fn))
return -EINVAL;
@@ -7018,7 +7034,39 @@ int tempfn_random(const char *p, char **ret) {
*x = 0;
- *ret = t;
+ *ret = path_kill_slashes(t);
+ return 0;
+}
+
+int tempfn_random_child(const char *p, char **ret) {
+ char *t, *x;
+ uint64_t u;
+ unsigned i;
+
+ assert(p);
+ assert(ret);
+
+ /* Turns this:
+ * /foo/bar/waldo
+ * Into this:
+ * /foo/bar/waldo/.3c2b6219aa75d7d0
+ */
+
+ t = new(char, strlen(p) + 2 + 16 + 1);
+ if (!t)
+ return -ENOMEM;
+
+ x = stpcpy(stpcpy(t, p), "/.");
+
+ u = random_u64();
+ for (i = 0; i < 16; i++) {
+ *(x++) = hexchar(u & 0xF);
+ u >>= 4;
+ }
+
+ *x = 0;
+
+ *ret = path_kill_slashes(t);
return 0;
}
diff --git a/src/shared/util.h b/src/shared/util.h
index 9a878ca1ac..a8ccf20bb8 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -1018,6 +1018,7 @@ int fflush_and_check(FILE *f);
int tempfn_xxxxxx(const char *p, char **ret);
int tempfn_random(const char *p, char **ret);
+int tempfn_random_child(const char *p, char **ret);
bool is_localhost(const char *hostname);