323a8537ab
find two users with the same UID (i.e. root and toor), but yp_mkdb(8) forbits duplicate keys, so only one of them will end up in the *.byuid maps (probably toor, since it comes after root in the template file). If I asked rpc.yppasswdd(8) to change toor's password, it would update the *.byname maps correctly, but incorrectly modify root's entry in the *.byuid maps since the only matching record with UID=0 in those maps belongs to root. To fix this, we check that both the name and UID are correct before trying to write new entries to the maps.