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authorDavid Herrmann <dh.herrmann@gmail.com>2014-12-30 11:37:35 +0100
committerDavid Herrmann <dh.herrmann@gmail.com>2014-12-30 11:37:35 +0100
commitd95eb43e90f19ff0c9aaff1c5fb1a7ed9fbd89a5 (patch)
tree87325a4eaa726f00809ced8090e7cf6b38b186ae /src/libsystemd/sd-bus
parent7d9fcc2bf6869993e5f38d5eb183fb59e8a52816 (diff)
bus: add sd_bus_emit_object_{added/removed}()
This implements two new helpers, discussed on systemd-devel about 1 year ago: sd_bus_emit_object_added() sd_bus_emit_object_removed() Both calls are equivalent to their respective counterpart sd_bus_emit_interfaces_{added/removed}(), but can figure out the list of interfaces themselves, instead of requiring the caller to provide them. Furthermore, both calls properly deal with builtin interfaces provided via org.freedesktop.DBus.* and alike. Both calls simply traverse a node and all its parent nodes to figure out a list of all interfaces registered as vtable or fallback. It then appends each of them, similar to the interfaces_{added/removed}() helpers. Note that interfaces_{added/removed}() runs a parent traversal for *each* passed interface. Therefore, it can simply bail out, once it found a parent node that implements a given interface. With object_{added/removed}() we cannot know the registered interfaces in advance, thus, we cannot run one traversal per node. Instead, we run a single traversal and remember all interfaces that we added. Therefore, a child-interface overrides all conflicting parent-interfaces. We keep a "Set *s" context to track those while climbing up the tree.
Diffstat (limited to 'src/libsystemd/sd-bus')
-rw-r--r--src/libsystemd/sd-bus/bus-objects.c369
-rw-r--r--src/libsystemd/sd-bus/test-bus-objects.c48
2 files changed, 417 insertions, 0 deletions
diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c
index e64743fa58..fc6c223283 100644
--- a/src/libsystemd/sd-bus/bus-objects.c
+++ b/src/libsystemd/sd-bus/bus-objects.c
@@ -2111,6 +2111,375 @@ _public_ int sd_bus_emit_properties_changed(
return sd_bus_emit_properties_changed_strv(bus, path, interface, names);
}
+static int object_added_append_all_prefix(
+ sd_bus *bus,
+ sd_bus_message *m,
+ Set *s,
+ const char *prefix,
+ const char *path,
+ bool require_fallback) {
+
+ const char *previous_interface = NULL;
+ struct node_vtable *c;
+ struct node *n;
+ int r;
+
+ assert(bus);
+ assert(m);
+ assert(s);
+ assert(prefix);
+ assert(path);
+
+ n = hashmap_get(bus->nodes, prefix);
+ if (!n)
+ return 0;
+
+ LIST_FOREACH(vtables, c, n->vtables) {
+ _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+ void *u = NULL;
+
+ if (require_fallback && !c->is_fallback)
+ continue;
+
+ r = node_vtable_get_userdata(bus, path, c, &u, &error);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+ if (r == 0)
+ continue;
+
+ if (!streq_ptr(c->interface, previous_interface)) {
+ /* If a child-node already handled this interface, we
+ * skip it on any of its parents. The child vtables
+ * always fully override any conflicting vtables of
+ * any parent node. */
+ if (set_get(s, c->interface))
+ continue;
+
+ r = set_put(s, c->interface);
+ if (r < 0)
+ return r;
+
+ if (previous_interface) {
+ r = sd_bus_message_close_container(m);
+ if (r < 0)
+ return r;
+ r = sd_bus_message_close_container(m);
+ if (r < 0)
+ return r;
+ }
+
+ r = sd_bus_message_open_container(m, 'e', "sa{sv}");
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "s", c->interface);
+ if (r < 0)
+ return r;
+ r = sd_bus_message_open_container(m, 'a', "{sv}");
+ if (r < 0)
+ return r;
+
+ previous_interface = c->interface;
+ }
+
+ r = vtable_append_all_properties(bus, m, path, c, u, &error);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+ }
+
+ if (previous_interface) {
+ r = sd_bus_message_close_container(m);
+ if (r < 0)
+ return r;
+ r = sd_bus_message_close_container(m);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+static int object_added_append_all(sd_bus *bus, sd_bus_message *m, const char *path) {
+ _cleanup_set_free_ Set *s = NULL;
+ char *prefix;
+ int r;
+
+ assert(bus);
+ assert(m);
+ assert(path);
+
+ /*
+ * This appends all interfaces registered on path @path. We first add
+ * the builtin interfaces, which are always available and handled by
+ * sd-bus. Then, we add all interfaces registered on the exact node,
+ * followed by all fallback interfaces registered on any parent prefix.
+ *
+ * If an interface is registered multiple times on the same node with
+ * different vtables, we merge all the properties across all vtables.
+ * However, if a child node has the same interface registered as one of
+ * its parent nodes has as fallback, we make the child overwrite the
+ * parent instead of extending it. Therefore, we keep a "Set" of all
+ * handled interfaces during parent traversal, so we skip interfaces on
+ * a parent that were overwritten by a child.
+ */
+
+ s = set_new(&string_hash_ops);
+ if (!s)
+ return -ENOMEM;
+
+ r = sd_bus_message_append(m, "{sa{sv}}", "org.freedesktop.DBus.Peer", 0);
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "{sa{sv}}", "org.freedesktop.DBus.Introspectable", 0);
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "{sa{sv}}", "org.freedesktop.DBus.Properties", 0);
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "{sa{sv}}", "org.freedesktop.DBus.ObjectManager", 0);
+ if (r < 0)
+ return r;
+
+ r = object_added_append_all_prefix(bus, m, s, path, path, false);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+
+ prefix = alloca(strlen(path) + 1);
+ OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
+ r = object_added_append_all_prefix(bus, m, s, prefix, path, true);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+ }
+
+ return 0;
+}
+
+int sd_bus_emit_object_added(sd_bus *bus, const char *path) {
+ BUS_DONT_DESTROY(bus);
+
+ _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
+ int r;
+
+ /*
+ * This emits an InterfacesAdded signal on the given path, by iterating
+ * all registered vtables and fallback vtables on the path. All
+ * properties are queried and included in the signal.
+ * This call is equivalent to sd_bus_emit_interfaces_added() with an
+ * explicit list of registered interfaces. However, unlike
+ * interfaces_added(), this call can figure out the list of supported
+ * interfaces itself. Furthermore, it properly adds the builtin
+ * org.freedesktop.DBus.* interfaces.
+ */
+
+ assert_return(bus, -EINVAL);
+ assert_return(object_path_is_valid(path), -EINVAL);
+ assert_return(!bus_pid_changed(bus), -ECHILD);
+
+ if (!BUS_IS_OPEN(bus->state))
+ return -ENOTCONN;
+
+ do {
+ bus->nodes_modified = false;
+ m = sd_bus_message_unref(m);
+
+ r = sd_bus_message_new_signal(bus, &m, path, "org.freedesktop.DBus.ObjectManager", "InterfacesAdded");
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_append_basic(m, 'o', path);
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_open_container(m, 'a', "{sa{sv}}");
+ if (r < 0)
+ return r;
+
+ r = object_added_append_all(bus, m, path);
+ if (r < 0)
+ return r;
+
+ if (bus->nodes_modified)
+ continue;
+
+ r = sd_bus_message_close_container(m);
+ if (r < 0)
+ return r;
+
+ } while (bus->nodes_modified);
+
+ return sd_bus_send(bus, m, NULL);
+}
+
+static int object_removed_append_all_prefix(
+ sd_bus *bus,
+ sd_bus_message *m,
+ Set *s,
+ const char *prefix,
+ const char *path,
+ bool require_fallback) {
+
+ const char *previous_interface = NULL;
+ struct node_vtable *c;
+ struct node *n;
+ int r;
+
+ assert(bus);
+ assert(m);
+ assert(s);
+ assert(prefix);
+ assert(path);
+
+ n = hashmap_get(bus->nodes, prefix);
+ if (!n)
+ return 0;
+
+ LIST_FOREACH(vtables, c, n->vtables) {
+ _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+ void *u = NULL;
+
+ if (require_fallback && !c->is_fallback)
+ continue;
+ if (streq_ptr(c->interface, previous_interface))
+ continue;
+
+ /* If a child-node already handled this interface, we
+ * skip it on any of its parents. The child vtables
+ * always fully override any conflicting vtables of
+ * any parent node. */
+ if (set_get(s, c->interface))
+ continue;
+
+ r = node_vtable_get_userdata(bus, path, c, &u, &error);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+ if (r == 0)
+ continue;
+
+ r = set_put(s, c->interface);
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_append(m, "s", c->interface);
+ if (r < 0)
+ return r;
+
+ previous_interface = c->interface;
+ }
+
+ return 0;
+}
+
+static int object_removed_append_all(sd_bus *bus, sd_bus_message *m, const char *path) {
+ _cleanup_set_free_ Set *s = NULL;
+ char *prefix;
+ int r;
+
+ assert(bus);
+ assert(m);
+ assert(path);
+
+ /* see sd_bus_emit_object_added() for details */
+
+ s = set_new(&string_hash_ops);
+ if (!s)
+ return -ENOMEM;
+
+ r = sd_bus_message_append(m, "s", "org.freedesktop.DBus.Peer");
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "s", "org.freedesktop.DBus.Introspectable");
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "s", "org.freedesktop.DBus.Properties");
+ if (r < 0)
+ return r;
+ r = sd_bus_message_append(m, "s", "org.freedesktop.DBus.ObjectManager");
+ if (r < 0)
+ return r;
+
+ r = object_removed_append_all_prefix(bus, m, s, path, path, false);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+
+ prefix = alloca(strlen(path) + 1);
+ OBJECT_PATH_FOREACH_PREFIX(prefix, path) {
+ r = object_removed_append_all_prefix(bus, m, s, prefix, path, true);
+ if (r < 0)
+ return r;
+ if (bus->nodes_modified)
+ return 0;
+ }
+
+ return 0;
+}
+
+int sd_bus_emit_object_removed(sd_bus *bus, const char *path) {
+ BUS_DONT_DESTROY(bus);
+
+ _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
+ int r;
+
+ /*
+ * This is like sd_bus_emit_object_added(), but emits an
+ * InterfacesRemoved signal on the given path. This only includes any
+ * registered interfaces but skips the properties. Note that this will
+ * call into the find() callbacks of any registered vtable. Therefore,
+ * you must call this function before destroying/unlinking your object.
+ * Otherwise, the list of interfaces will be incomplete. However, note
+ * that this will *NOT* call into any property callback. Therefore, the
+ * object might be in an "destructed" state, as long as we can find it.
+ */
+
+ assert_return(bus, -EINVAL);
+ assert_return(object_path_is_valid(path), -EINVAL);
+ assert_return(!bus_pid_changed(bus), -ECHILD);
+
+ if (!BUS_IS_OPEN(bus->state))
+ return -ENOTCONN;
+
+ do {
+ bus->nodes_modified = false;
+ m = sd_bus_message_unref(m);
+
+ r = sd_bus_message_new_signal(bus, &m, path, "org.freedesktop.DBus.ObjectManager", "InterfacesRemoved");
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_append_basic(m, 'o', path);
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_open_container(m, 'a', "s");
+ if (r < 0)
+ return r;
+
+ r = object_removed_append_all(bus, m, path);
+ if (r < 0)
+ return r;
+
+ if (bus->nodes_modified)
+ continue;
+
+ r = sd_bus_message_close_container(m);
+ if (r < 0)
+ return r;
+
+ } while (bus->nodes_modified);
+
+ return sd_bus_send(bus, m, NULL);
+}
+
static int interfaces_added_append_one_prefix(
sd_bus *bus,
sd_bus_message *m,
diff --git a/src/libsystemd/sd-bus/test-bus-objects.c b/src/libsystemd/sd-bus/test-bus-objects.c
index 06b8904f13..acf67a52b3 100644
--- a/src/libsystemd/sd-bus/test-bus-objects.c
+++ b/src/libsystemd/sd-bus/test-bus-objects.c
@@ -176,6 +176,28 @@ static int emit_interfaces_removed(sd_bus *bus, sd_bus_message *m, void *userdat
return 1;
}
+static int emit_object_added(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *error) {
+ int r;
+
+ assert_se(sd_bus_emit_object_added(bus, m->path) >= 0);
+
+ r = sd_bus_reply_method_return(m, NULL);
+ assert_se(r >= 0);
+
+ return 1;
+}
+
+static int emit_object_removed(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *error) {
+ int r;
+
+ assert_se(sd_bus_emit_object_removed(bus, m->path) >= 0);
+
+ r = sd_bus_reply_method_return(m, NULL);
+ assert_se(r >= 0);
+
+ return 1;
+}
+
static const sd_bus_vtable vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_METHOD("AlterSomething", "s", "s", something_handler, 0),
@@ -186,6 +208,8 @@ static const sd_bus_vtable vtable[] = {
SD_BUS_METHOD("NoOperation", NULL, NULL, NULL, 0),
SD_BUS_METHOD("EmitInterfacesAdded", NULL, NULL, emit_interfaces_added, 0),
SD_BUS_METHOD("EmitInterfacesRemoved", NULL, NULL, emit_interfaces_removed, 0),
+ SD_BUS_METHOD("EmitObjectAdded", NULL, NULL, emit_object_added, 0),
+ SD_BUS_METHOD("EmitObjectRemoved", NULL, NULL, emit_object_removed, 0),
SD_BUS_VTABLE_END
};
@@ -456,6 +480,30 @@ static int client(struct context *c) {
sd_bus_message_unref(reply);
reply = NULL;
+ r = sd_bus_call_method(bus, "org.freedesktop.systemd.test", "/foo", "org.freedesktop.systemd.test", "EmitObjectAdded", &error, NULL, "");
+ assert_se(r >= 0);
+
+ r = sd_bus_process(bus, &reply);
+ assert_se(r > 0);
+
+ assert_se(sd_bus_message_is_signal(reply, "org.freedesktop.DBus.ObjectManager", "InterfacesAdded"));
+ bus_message_dump(reply, stdout, BUS_MESSAGE_DUMP_WITH_HEADER);
+
+ sd_bus_message_unref(reply);
+ reply = NULL;
+
+ r = sd_bus_call_method(bus, "org.freedesktop.systemd.test", "/foo", "org.freedesktop.systemd.test", "EmitObjectRemoved", &error, NULL, "");
+ assert_se(r >= 0);
+
+ r = sd_bus_process(bus, &reply);
+ assert_se(r > 0);
+
+ assert_se(sd_bus_message_is_signal(reply, "org.freedesktop.DBus.ObjectManager", "InterfacesRemoved"));
+ bus_message_dump(reply, stdout, BUS_MESSAGE_DUMP_WITH_HEADER);
+
+ sd_bus_message_unref(reply);
+ reply = NULL;
+
r = sd_bus_call_method(bus, "org.freedesktop.systemd.test", "/foo", "org.freedesktop.systemd.test", "Exit", &error, NULL, "");
assert_se(r >= 0);