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.

`-ENOMEM`

  Memory allocation failed.

## See Also

sd-bus 3, busctl 1, sd_bus_add_fallback_vtable 3, sd_bus_slot_unref 3