SD_EVENT_SOURCE_SET_Dsd_event_source_seSD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)

NAME
       sd_event_source_set_destroy_callback,
       sd_event_source_get_destroy_callback, sd_event_destroy_t - Define the
       callback function for resource cleanup

SYNOPSIS
       #include <systemd/sd-event.h>

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

       int sd_event_source_set_destroy_callback(sd_event_source *source,
                                                sd_event_destroy_t callback);

       int sd_event_source_get_destroy_callback(sd_event_source *source,
                                                sd_event_destroy_t *callback);

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

       sd_event_source_get_destroy_callback() returns the current callback for
       source in the callback parameter.

RETURN VALUE
       On success, sd_event_source_set_destroy_callback() returns 0 or a
       positive integer. On failure, it returns a negative errno-style error
       code.

       sd_event_source_get_destroy_callback() returns positive if the destroy
       callback function is set, 0 if not. On failure, returns a negative
       errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           The source parameter is NULL.

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

SEE ALSO
       systemd(1), sd-event(3), sd_event_add_io(3), sd_event_add_time(3),
       sd_event_add_signal(3), sd_event_add_child(3), sd_event_add_inotify(3),
       sd_event_add_defer(3), sd_event_source_set_userdata(3)

systemd 252                            SD_EVENT_SOURCE_SET_DESTROY_CALLBACK(3)

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