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)

systemd 257.9                                                                      SD_BUS_ADD_NODE_ENUMERATOR(3)