Allow CREATE/ALTER ROLE PASSWORD NULL to allow restoring the default state

of having no password.

doc/src/sgml/ref/create_role.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_role.sgml,v 1.5 2005/12/18 02:17:16 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_role.sgml,v 1.6 2005/12/23 16:46:39 petere Exp $
 PostgreSQL documentation
 -->
 
@@ -188,10 +188,13 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
       <listitem>
        <para>
         Sets the role's password.  (A password is only of use for
-        roles having the <literal>LOGIN</literal> attribute, but you can
-        nonetheless define one for roles without it.)
-        If you do not plan to use password
-        authentication you can omit this option.
+        roles having the <literal>LOGIN</literal> attribute, but you
+        can nonetheless define one for roles without it.)  If you do
+        not plan to use password authentication you can omit this
+        option.  If no password is specified, the password will be set
+        to null and password authentication will always fail for that
+        user.  A null password can optionally be written explicitly as
+        <literal>PASSWORD NULL</literal>.
        </para>
       </listitem>
      </varlistentry>

src/backend/commands/user.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.166 2005/11/22 18:17:09 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.167 2005/12/23 16:46:39 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -225,7 +225,7 @@ CreateRole(CreateRoleStmt *stmt)
 				 defel->defname);
 	}
 
-	if (dpassword)
+	if (dpassword && dpassword->arg)
 		password = strVal(dpassword->arg);
 	if (dissuper)
 		issuper = intVal(dissuper->arg) != 0;
@@ -517,7 +517,7 @@ AlterRole(AlterRoleStmt *stmt)
 				 defel->defname);
 	}
 
-	if (dpassword)
+	if (dpassword && dpassword->arg)
 		password = strVal(dpassword->arg);
 	if (dissuper)
 		issuper = intVal(dissuper->arg);
@@ -573,7 +573,7 @@ AlterRole(AlterRoleStmt *stmt)
 			  !dconnlimit &&
 			  !rolemembers &&
 			  !validUntil &&
-			  password &&
+			  dpassword &&
 			  roleid == GetUserId()))
 			ereport(ERROR,
 					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -651,6 +651,13 @@ AlterRole(AlterRoleStmt *stmt)
 		new_record_repl[Anum_pg_authid_rolpassword - 1] = 'r';
 	}
 
+	/* unset password */
+	if (dpassword && dpassword->arg == NULL)
+	{
+		new_record_repl[Anum_pg_authid_rolpassword - 1] = 'r';
+		new_record_nulls[Anum_pg_authid_rolpassword - 1] = 'n';
+	}
+
 	/* valid until */
 	if (validUntil)
 	{

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.517 2005/12/11 10:54:27 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.518 2005/12/23 16:46:39 petere Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -616,6 +616,10 @@ OptRoleElem:
 					$$ = makeDefElem("password",
 									 (Node *)makeString($2));
 				}
+			| PASSWORD NULL_P
+				{
+					$$ = makeDefElem("password", NULL);
+				}
 			| ENCRYPTED PASSWORD Sconst
 				{
 					$$ = makeDefElem("encryptedPassword",