int sd_event_exit(sd_event *event, int code);
int sd_event_get_exit_code(sd_event *event, int *code);
When exiting is requested the event loop will stop listening for and dispatching regular event sources. Instead it will proceed with executing only event sources registered with sd_event_add_exit(3) in the order defined by their priority. After all exit event sources have been dispatched the event loop is terminated.
If sd_event_exit() is invoked a second time while the event loop is still processing exit event sources, the exit code stored in the event loop object is updated, but otherwise no further operation is executed.
sd_event_get_exit_code() may be used to query the exit code passed into sd_event_exit() earlier.
While the full positive and negative integer ranges may be used for the exit code, care should be taken not pick exit codes that conflict with regular exit codes returned by sd_event_loop(), if these exit codes shall be distinguishable.