NAME

       sd_bus_add_node_enumerator - Add a node enumerator for a D-Bus object path prefix

SYNOPSIS

       #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.

NOTES

       Functions described here are available as a shared library, which can be compiled against
       and linked to with the libsystemd pkg-config(1) file.

       The code described here uses getenv(3), which is declared to be not multi-thread-safe.
       This means that the code calling the functions described here must not call setenv(3) from
       a parallel thread. It is recommended to only do calls to setenv() from an early phase of
       the program when no other threads have been started.

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)