doing 
  for(i=0;i<count;i++){
    smbc_opendir();
    smbc_readdir();
    smbc_closedir();
  }
and compare valgrind results for different "count" value i found
  1) read samba directory:                 OK
  2) read contents of samba share:         OK
  3) read list of shares:                  MEMORY LEAK
  4) read list of computer in samba group: MEMORY LEAK
  5) read list of samba groups:            MEMORY LEAK

see the test souce/results in attachment. Edit and execute "x.sh" to repeat the test in your environment.