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authorDavid Herrmann <dh.herrmann@gmail.com>2015-09-05 19:43:29 +0200
committerDavid Herrmann <dh.herrmann@gmail.com>2015-09-05 19:43:29 +0200
commit44eb1adda98f6733264c0e8fbc569656c6ff2de0 (patch)
treec4c1e07ea77907e2c4fd9adaa4b53a1fbfb2d048 /src/libsystemd/sd-bus
parentb47c788854600ca691382d222ffeac335f619da9 (diff)
sd-bus: make introspection data non-recursive
Currently, our introspection data looks like this: <node> <interface name="org.freedesktop.DBus.Peer"> ... </interface> <interface name="org.freedesktop.DBus.Introspectable"> ... </interface> <interface name="org.freedesktop.DBus.Properties"> ... </interface> <node name="org"/> <node name="org/freedesktop"/> <node name="org/freedesktop/login1"/> <node name="org/freedesktop/login1/user"/> <node name="org/freedesktop/login1/user/self"/> <node name="org/freedesktop/login1/user/_1000"/> <node name="org/freedesktop/login1/seat"/> <node name="org/freedesktop/login1/seat/self"/> <node name="org/freedesktop/login1/seat/seat0"/> <node name="org/freedesktop/login1/session"/> <node name="org/freedesktop/login1/session/self"/> <node name="org/freedesktop/login1/session/c1"/> </node> (ordered alphabetically for better visibility) This is grossly incorrect. The spec says that we're allowed to return non-directed children, however, it does not allow us to return data recursively in multiple parents. If we return "org", then we must not return anything else that starts with "org/". It is unclear, whether we can include child-nodes as a tree. Moreover, it is usually not what the caller wants. Hence, this patch changes sd-bus to never return introspection data recursively. Instead, only a single child-layer is returned. This patch relies on enumerators to never return hierarchies. If someone registers an enumerator via sd_bus_add_enumerator, they better register sub-enumerators if they support *TRUE* hierarchies. Each enumerator is treated as a single layer and not filtered. Enumerators are still allowed to return nested data. However, that data is still required to be a single hierarchy. For instance, returning "/org/foo" and "/com/bar" is fine, but including "/com" or "/org" in that dataset is not. This should be the default for enumerators and I see no reason to filter in sd-bus. Moreover, filtering that data-set would require to sort the strv by path and then do prefix-filtering. This is O(n log n), which would be fine, but still better to avoid. Fixes #664.
Diffstat (limited to 'src/libsystemd/sd-bus')
-rw-r--r--src/libsystemd/sd-bus/bus-objects.c22
1 files changed, 15 insertions, 7 deletions
diff --git a/src/libsystemd/sd-bus/bus-objects.c b/src/libsystemd/sd-bus/bus-objects.c
index 0593aa658a..1d061cb9cf 100644
--- a/src/libsystemd/sd-bus/bus-objects.c
+++ b/src/libsystemd/sd-bus/bus-objects.c
@@ -169,11 +169,18 @@ static int add_enumerated_to_set(
return 0;
}
+enum {
+ /* if set, add_subtree() works recursively */
+ CHILDREN_RECURSIVE = (1U << 1),
+ /* if set, add_subtree() scans object-manager hierarchies recursively */
+ CHILDREN_SUBHIERARCHIES = (1U << 0),
+};
+
static int add_subtree_to_set(
sd_bus *bus,
const char *prefix,
struct node *n,
- bool skip_subhierarchies,
+ unsigned int flags,
Set *s,
sd_bus_error *error) {
@@ -205,8 +212,9 @@ static int add_subtree_to_set(
if (r < 0 && r != -EEXIST)
return r;
- if (!skip_subhierarchies || !i->object_managers) {
- r = add_subtree_to_set(bus, prefix, i, skip_subhierarchies, s, error);
+ if ((flags & CHILDREN_RECURSIVE) &&
+ ((flags & CHILDREN_SUBHIERARCHIES) || !i->object_managers)) {
+ r = add_subtree_to_set(bus, prefix, i, flags, s, error);
if (r < 0)
return r;
if (bus->nodes_modified)
@@ -221,7 +229,7 @@ static int get_child_nodes(
sd_bus *bus,
const char *prefix,
struct node *n,
- bool skip_subhierarchies,
+ unsigned int flags,
Set **_s,
sd_bus_error *error) {
@@ -237,7 +245,7 @@ static int get_child_nodes(
if (!s)
return -ENOMEM;
- r = add_subtree_to_set(bus, prefix, n, skip_subhierarchies, s, error);
+ r = add_subtree_to_set(bus, prefix, n, flags, s, error);
if (r < 0) {
set_free_free(s);
return r;
@@ -907,7 +915,7 @@ static int process_introspect(
assert(n);
assert(found_object);
- r = get_child_nodes(bus, m->path, n, false, &s, &error);
+ r = get_child_nodes(bus, m->path, n, 0, &s, &error);
if (r < 0)
return bus_maybe_reply_error(m, r, &error);
if (bus->nodes_modified)
@@ -1173,7 +1181,7 @@ static int process_get_managed_objects(
if (require_fallback || !n->object_managers)
return 0;
- r = get_child_nodes(bus, m->path, n, true, &s, &error);
+ r = get_child_nodes(bus, m->path, n, CHILDREN_RECURSIVE, &s, &error);
if (r < 0)
return r;
if (bus->nodes_modified)