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)
