SQL & PL/SQL :: Hierarchical Retrieving With Cycles

first of all sample data;

create table test_circular_data(c1 varchar2(10),c2 varchar2(10));
insert into test_circular_data values ('c1','l2');
insert into test_circular_data values ('c1','l3');
insert into test_circular_data values ('c3','l3');
insert into test_circular_data values ('c4','l3');

commit;

There is a circular relation between columns c1 and c2, so what I'm trying to retrieve is something like that :

c1--> l2 --> l3 --> c3 --> c4

The steps to get that result is :

1.- c1 related to l2 : c1-->l2
2.- c1 related to l3 : c1-->l2-->l3
3.- l3 in the list and related to c3 : c1-->l2-->l3-->c3
4.- l3 in the list and related to c4 : c1-->l2-->l3-->c3-->c4