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   sd_bus_slot_get_destroy_callback    ( 3 )

определите функцию обратного вызова для очистки ресурсов (define the callback function for resource cleanup)

Имя (Name)

sd_bus_slot_set_destroy_callback,
       sd_bus_slot_get_destroy_callback,
       sd_bus_track_set_destroy_callback,
       sd_bus_track_get_destroy_callback, sd_bus_destroy_t - Define the
       callback function for resource cleanup

Синопсис (Synopsis)

#include <systemd/sd-bus.h>

typedef int (*sd_bus_destroy_t)(void *userdata);

int sd_bus_slot_set_destroy_callback(sd_bus_slot *slot, sd_bus_destroy_t callback);

int sd_bus_slot_get_destroy_callback(sd_bus_slot *slot, sd_bus_destroy_t *callback);

int sd_bus_track_set_destroy_callback(sd_bus_track *track, sd_bus_destroy_t callback);

int sd_bus_track_get_destroy_callback(sd_bus_track *track, sd_bus_destroy_t *callback);


Описание (Description)

sd_bus_slot_set_destroy_callback() sets callback as the callback
       function to be called right before the bus slot object slot is
       deallocated. The userdata pointer from the slot object will be
       passed as the userdata parameter. This pointer can be set by an
       argument to the constructor functions, see sd_bus_add_match(3),
       or directly, see sd_bus_slot_set_userdata(3). This callback
       function is called even if userdata is NULL. Note that this
       callback is invoked at a time where the bus slot object itself is
       already invalidated, and executing operations or taking new
       references to the bus slot object is not permissible.

sd_bus_slot_get_destroy_callback() returns the current callback for slot in the callback parameter.

sd_bus_track_set_destroy_callback() and sd_bus_track_get_destroy_callback() provide equivalent functionality for the userdata pointer associated with bus peer tracking objects. For details about bus peer tracking objects, see sd_bus_track_new(3).


Возвращаемое значение (Return value)

On success, sd_bus_slot_set_destroy_callback() and
       sd_bus_track_set_destroy_callback() return 0 or a positive
       integer. On failure, they return a negative errno-style error
       code.

sd_bus_slot_get_destroy_callback() and sd_bus_track_get_destroy_callback() return positive if the destroy callback function is set, 0 if not. On failure, they return a negative errno-style error code.

Errors Returned errors may indicate the following problems:

-EINVAL The slot or track parameter is NULL.


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_floating(3),
       sd_bus_add_match(3), sd_bus_track_new(3),
       sd_bus_slot_set_userdata(3), sd_bus_track_set_userdata(3)