# sd_bus_slot_set_floating

## 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
           made into a regular (non-floating) slot object, otherwise it is
           made into a 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,
               library or module instance.
    
           **-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



           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.
    


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