event_open_with_pid
FAIL_IF(event_open_with_pid(&event, pid));
FAIL_IF(event_open_with_pid(&event, pid));
FAIL_IF(event_open_with_pid(event, child_pid));
FAIL_IF(event_open_with_pid(event, child_pid));
int event_open_with_pid(struct event *e, pid_t pid);