This should simplify the prototype a bit. The bus parameter is redundant
in most cases, and in the few where it matters it can be derived from
the message via sd_bus_message_get_bus().
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.
They do not use any functions from libcap directly. The CAP_SYS_ADMIN constant
in use by bus-objects.c comes from <linux/capability.h> imported through
"missing.h". The "missing.h" header is imported through "util.h" which gets
imported in "bus-util.h".
Tested that everything builds cleanly after this change.
If we call into user callbacks, we must always propagate possible errors.
Fix bus_node_exists() to do that and adjust the callers (which already
partially propagated the error).
Also speed up that function by first checking for registered enumerators
and/or object-managers.
The dbus-spec clearly specifies that GetManagedObjects() should only work
on the root-path of an object-tree. But on that path, it works regardless
whether there are any objects available or not.
We could, technically, define all sub-paths as a root-path of its own
sub-tree. However, if we do that, we enter undefined territory:
Imagine only a fallback vtable is registered. We want
GetManagedObjects() to *NOT* fail with UNKNOWN_METHOD if it is called
on a valid sub-tree of the fallback. On the other hand, we don't want
it to work on arbitrary sub-tree. Something like:
/path/to/fallback/foobar/foobar/foobar/invalid/foobar
should not work.
However, there is no way to know which paths on a fallback are valid
without looking at there registered objects. If no objects are
registered, we have no way to figure it out.
Therefore, we now try to follow the dbus spec by only returning valid data
on registered root-paths. We treat each path as root which was registered
an object-manager on via add_object_manager(). So applications can now
directly control which paths to place an object-manager on.
We also fix the introspection to not return object-manager interfaces on
non-root paths.
Also fixes some dead-code paths initially reported by Philippe De Swert.
It is redundant to store 'hash' and 'compare' function pointers in
struct Hashmap separately. The functions always comprise a pair.
Store a single pointer to struct hash_ops instead.
systemd keeps hundreds of hashmaps, so this saves a little bit of
memory.
This is a generalization of the vtable privilege check we already have,
but exported, and hence useful when preparing for a polkit change.
This will deal with the complexity that on dbus1 one cannot trust the
capability field we retrieve via the bus, since it is read via
/proc/$$/stat (and thus might be out-of-date) rather than directly from
the message (like on kdbus) or bus connection (as for uid creds on
dbus1).
Also, port over all code to this new API.
This makes callback behaviour more like sd-event or sd-resolve, and
creates proper object for unregistering callbacks.
Taking the refernce to the slot is optional. If not taken life time of
the slot will be bound to the underlying bus object (or in the case of
an async call until the reply has been recieved).
gcc (4.8.2, arm) doesn't understand that vtable_property_get_userdata()
will always set 'u' when it returns > 0. Hence, the warning is bogus,
but anyway.
src/libsystemd/sd-bus/bus-objects.c:510:19: warning: 'u' may be used uninitialized in this function [-Wmaybe-uninitialized]
(and yes, indeed, even the reported line numbers are bogus in this case)
Previously the returned object of constructor functions where sometimes
returned as last, sometimes as first and sometimes as second parameter.
Let's clean this up a bit. Here are the new rules:
1. The object the new object is derived from is put first, if there is any
2. The object we are creating will be returned in the next arguments
3. This is followed by any additional arguments
Rationale:
For functions that operate on an object we always put that object first.
Constructors should probably not be too different in this regard. Also,
if the additional parameters might want to use varargs which suggests to
put them last.
Note that this new scheme only applies to constructor functions, not to
all other functions. We do give a lot of freedom for those.
Note that this commit only changes the order of the new functions we
added, for old ones we accept the wrong order and leave it like that.
