NAME

       sd_bus_slot_set_floating, sd_bus_slot_get_floating - Control whether a bus slot object is "floating"

SYNOPSIS

       #include <systemd/sd-bus.h>

       int sd_bus_slot_set_floating(sd_bus_slot *slot, int b);

       int sd_bus_slot_get_floating(sd_bus_slot *slot);

DESCRIPTION

       sd_bus_slot_set_floating() controls whether the specified bus slot object slot shall be "floating" or
       not. A floating bus slot object's lifetime is bound to the lifetime of the bus object it is associated
       with, meaning that it remains allocated as long as the bus object itself and is freed automatically when
       the bus object is freed. Regular (i.e. non-floating) bus slot objects keep the bus referenced, hence the
       bus object remains allocated at least as long as there remains at least one referenced bus slot object
       around. The floating state hence controls the direction of referencing between the bus object and the bus
       slot objects: if floating the bus pins the bus slot, and otherwise the bus slot pins the bus objects. Use
       sd_bus_slot_set_floating() to switch between both modes: if the b parameter is zero, the slot object is
       considered floating, otherwise it is made a regular (non-floating) slot object.

       Bus slot objects may be allocated with calls such as sd_bus_add_match(3). If the slot of these functions
       is non-NULL the slot object will be of the regular kind (i.e. non-floating), otherwise it will be created
       floating. With sd_bus_slot_set_floating() a bus slot object allocated as regular can be converted into a
       floating object and back. This is particularly useful for creating a bus slot object, then changing
       parameters of it, and then turning it into a floating object, whose lifecycle is managed by the bus
       object.

       sd_bus_slot_get_floating() returns the current floating state of the specified bus slot object. It
       returns negative on error, zero if the bus slot object is a regular (non-floating) object and positive
       otherwise.

RETURN VALUE

       On success, these functions return 0 or a positive integer. On failure, they return a negative
       errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           The slot parameter is NULL.

       -ECHILD
           The bus connection has been created in a different process.

       -ESTALE
           The bus object the specified bus slot object is associated with has already been freed, and hence no
           change in the floating state can be made anymore.

NOTES

       These APIs are implemented as a shared library, which can be compiled and linked to with the
       libsystemd pkg-config(1) file.

SEE ALSO

       systemd(1), sd-bus(3), sd_bus_slot_set_destroy_callback(3), sd_bus_add_match(3)