sd_bus_add_node_enumerator
systemd
sd_bus_add_node_enumerator
3
sd_bus_add_node_enumerator
Add a node enumerator for a D-Bus object path prefix
#include <systemd/sd-bus.h>
typedef int (*
sd_bus_node_enumerator_t
)
sd_bus *
bus
const char *
prefix
void *
userdata
char ***
ret_nodes
sd_bus_error *
ret_error
int
sd_bus_add_node_enumerator
sd_bus *
bus
sd_bus_slot **
slot
const char *
path
sd_bus_node_enumerator_t
callback
void *
userdata
Description
sd_bus_add_node_enumerator() adds a D-Bus node enumerator for the given path prefix. The given callback is called to enumerate all the available objects with the given path prefix when required (e.g. when org.freedesktop.DBus.Introspectable.Introspect or org.freedesktop.DBus.ObjectManager.GetManagedObjects are called on a D-Bus service managed by sd-bus).
callback is called with the path and userdata pointer registered with sd_bus_add_node_enumerator(). When called, it should store all the child object paths of the given path prefix in ret_nodes with a NULL terminator item. The callback should return a non-negative value on success. If an error occurs, it can either return a negative integer, set ret_error to a non-empty error or do both. Any errors returned by the callback are encoded as D-Bus errors and sent back to the caller. Errors in ret_error take priority over negative return values.
Note that a node enumerator callback will only ever be called for a single path prefix and hence, for normal operation, prefix can be ignored. Also, a node enumerator is only used to enumerate the available child objects under a given prefix. To install a handler for a set of dynamic child objects, use sd_bus_add_fallback_vtable(3).
When sd_bus_add_node_enumerator() succeeds, a slot is created internally. If the output parameter <slot> is NULL, a "floating" slot object is created, see sd_bus_slot_set_floating(3). Otherwise, a pointer to the slot object is returned. In that case, the reference to the slot object should be dropped when the node enumerator is not needed anymore, see sd_bus_slot_unref(3).
Return Value
On success, sd_bus_add_node_enumerator() returns a non-negative integer. On failure, it returns a negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-EINVAL
One of the required parameters is NULL or path is not a valid object path.
-ENOPKG
The bus cannot be resolved.
-ECHILD
The bus was created in a different process, library or module instance.
-ENOMEM
Memory allocation failed.
History
sd_bus_node_enumerator_t() and sd_bus_add_node_enumerator() were added in version 221.
See Also
sd-bus(3), busctl(1), sd_bus_add_fallback_vtable(3), sd_bus_slot_unref(3)