| SD_BUS_ADD_NODE_ENUMERATOR(3) | sd_bus_add_node_enumerator | SD_BUS_ADD_NODE_ENUMERATOR(3) |
.SH "NAME" sd_bus_add_node_enumerator - Add a node enumerator for a
D-Bus object path prefix
.SH "SYNOPSIS"
#include <systemd/sd-bus.h>
.HP 960u typedef int
(*sd_bus_node_enumerator_t)(sd_bus *bus,
const char *prefix,
void *userdata, char ***ret_nodes,
sd_bus_error *ret_error);
.HP 744u int sd_bus_add_node_enumerator(sd_bus *bus,
sd_bus_slot **slot,
const char *path,
sd_bus_node_enumerator_t callback,
void *userdata);
.SH "DESCRIPTION"
.PP 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).
.PP 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.
.PP 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).
.PP 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).
.SH "RETURN VALUE"
.PP On success, sd_bus_add_node_enumerator() returns a non-negative
integer. On failure, it returns a negative errno-style error code.
.SS "Errors"
.PP Returned errors may indicate the following problems:
.PP -EINVAL
One of the required parameters is NULL or path is not a valid
object path.
.RE
.PP -ENOPKG
The bus cannot be resolved.
.RE
.PP -ECHILD
The bus was created in a different process, library or module instance.
.RE
.PP -ENOMEM
Memory allocation failed.
.RE
.SH "NOTES"
.PP Functions described here are available as a shared library, which can be
compiled against and linked to with the
libsystemd pkg-config(1) file.
.PP All functions listed here are thread-agnostic and only a single thread
may operate on a given object at any given time. Different threads may
access the same object at different times. Multiple independent objects may
be used from different threads in parallel.
.PP 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.
.SH "HISTORY"
.PP sd_bus_node_enumerator_t() and sd_bus_add_node_enumerator()
were added in version 221.
.SH "SEE ALSO"
.PP sd-bus(3), busctl(1), sd_bus_add_fallback_vtable(3),
sd_bus_slot_unref(3)
| systemd 262.2 |