nss_db_root
typedef struct nss_db_root nss_db_root_t;
nss_db_root_t *nss_db_root;
nss_db_root = &db_root_hosts;
nss_db_root = &db_root_ipnodes;
res = nss_search(nss_db_root, nss_initf,
nss_db_root_t *nss_db_root;
nss_db_root = &db_root_hosts;
nss_db_root = &db_root_ipnodes;
res = nss_search(nss_db_root, nss_initf, dbop, &arg);