sd_bus_slot_get_destroy_callback(3) — Linux manual page



NAME         top

       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

SYNOPSIS         top

       #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);

DESCRIPTION         top

       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

       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).

RETURN VALUE         top

       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.

       Returned errors may indicate the following problems:

           The slot or track parameter is NULL.

NOTES         top

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

SEE ALSO         top

       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)

COLOPHON         top

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systemd 247                              SD_BUS_SLOT_SET_DESTROY_CALLBACK(3)

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