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   sd_bus_slot_set_floating    ( 3 )

контроль того, является ли объект слота шины плавающим (Control whether a bus slot object is "floating")

Имя (Name)

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

Синопсис (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);


Описание (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.


Возвращаемое значение (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.


Примечание (Note)

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

Смотри также (See also)

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