sd_bus_add_node_enumerator(3) — Linux manual page


SD_BUS_A...UMERATOR(3) sd_bus_add_node_enumerator SD_BUS_A...UMERATOR(3)

NAME         top

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

SYNOPSIS         top

       #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         top

       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

       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         top

       On success, sd_bus_add_node_enumerator() returns a non-negative
       integer. On failure, it returns a negative errno-style error

       Returned errors may indicate the following problems:

           One of the required parameters is NULL or path is not a valid
           object path.

           Added in version 246.

           The bus cannot be resolved.

           Added in version 246.

           The bus was created in a different process, library or module

           Added in version 246.

           Memory allocation failed.

           Added in version 246.

NOTES         top

       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

HISTORY         top

       sd_bus_node_enumerator_t() and sd_bus_add_node_enumerator() were
       added in version 246.

SEE ALSO         top

       sd-bus(3), busctl(1), sd_bus_add_fallback_vtable(3),

COLOPHON         top

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       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
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       (which is not part of the original manual page), send a mail to

systemd 255                                       SD_BUS_A...UMERATOR(3)

Pages that refer to this page: sd-bus(3)systemd.directives(7)systemd.index(7)