machined: add API for querying the OS release of a machine image

This adds a bus call GetImageOSRelease() to the Manager interface that
retrieves the /etc/os-release file of a machine image. It matches the existing
GetMachineOSRelease() call, however operates on a disk image rather than a
running container.

The backend for this call on .raw images is implemented via the generalized
image dissector, which makes this scheme relatively easy to implement.

1 files changed, 52 insertions, 0 deletions

diff --git a/src/machine/machined-dbus.c b/src/machine/machined-dbus.c
index 3ee3938ebb..fd9e5b56fc 100644
--- a/src/machine/machined-dbus.c
+++ b/src/machine/machined-dbus.c
@@ -825,6 +825,30 @@ static int method_mark_image_read_only(sd_bus_message *message, void *userdata,
         return bus_image_method_mark_read_only(message, i, error);
 }
 
+static int method_get_image_os_release(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        _cleanup_(image_unrefp) Image *i = NULL;
+        const char *name;
+        int r;
+
+        assert(message);
+
+        r = sd_bus_message_read(message, "s", &name);
+        if (r < 0)
+                return r;
+
+        if (!image_name_is_valid(name))
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Image name '%s' is invalid.", name);
+
+        r = image_find(name, &i);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return sd_bus_error_setf(error, BUS_ERROR_NO_SUCH_IMAGE, "No image '%s' known", name);
+
+        i->userdata = userdata;
+        return bus_image_method_get_os_release(message, i, error);
+}
+
 static int clean_pool_done(Operation *operation, int ret, sd_bus_error *error) {
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         _cleanup_fclose_ FILE *f = NULL;
@@ -1396,6 +1420,7 @@ const sd_bus_vtable manager_vtable[] = {
         SD_BUS_METHOD("RenameImage", "ss", NULL, method_rename_image, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("CloneImage", "ssb", NULL, method_clone_image, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("MarkImageReadOnly", "sb", NULL, method_mark_image_read_only, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("GetImageOSRelease", "s", "a{ss}", method_get_image_os_release, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("SetPoolLimit", "t", NULL, method_set_pool_limit, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("SetImageLimit", "st", NULL, method_set_image_limit, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("CleanPool", "s", "a(st)", method_clean_pool, SD_BUS_VTABLE_UNPRIVILEGED),
@@ -1804,3 +1829,30 @@ int manager_add_machine(Manager *m, const char *name, Machine **_machine) {
 
         return 0;
 }
+
+int bus_reply_pair_array(sd_bus_message *m, char **l) {
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        char **k, **v;
+        int r;
+
+        r = sd_bus_message_new_method_return(m, &reply);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(reply, 'a', "{ss}");
+        if (r < 0)
+                return r;
+
+        STRV_FOREACH_PAIR(k, v, l) {
+                r = sd_bus_message_append(reply, "{ss}", *k, *v);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_bus_message_close_container(reply);
+        if (r < 0)
+                return r;
+
+        return sd_bus_send(NULL, reply, NULL);
+
+}