idmap_getwinnamebyuid
rc = idmap_getwinnamebyuid(uid, 0, &idmap_buf, NULL);
(void) idmap_getwinnamebyuid(rid, flag,
extern idmap_stat idmap_getwinnamebyuid(uid_t, int, char **, char **);
error = idmap_getwinnamebyuid(who,
stat = idmap_getwinnamebyuid(pid, flag, &name, NULL);