sd_event_source_get_event — Retrieve the event loop of an event source
#include <systemd/sd-event.h>
sd_event* sd_event_source_get_event( | sd_event_source *source); | 
sd_event_source_get_event() may be used
    to retrieve the event loop object the event source object specified
    as source is associated with. The event
    loop object is specified when creating an event source object with
    calls such as
    sd_event_add_io(3)
    or
    sd_event_add_time(3).
On success, sd_event_source_get_event()
    returns the associated event loop object. On failure, it returns
    NULL.
These APIs are implemented as a shared
  library, which can be compiled and linked to with the
  libsystemd pkg-config(1)
  file.