Update per-column ACLs, not only per-table ACL, when changing table owner.

We forgot to modify column ACLs, so privileges were still shown as having
been granted by the old owner.  This meant that neither the new owner nor
a superuser could revoke the now-untraceable-to-table-owner permissions.
Per bug #6350 from Marc Balmer.

This has been wrong since column ACLs were added, so back-patch to 8.4.

Author: tglsfdc

src/backend/commands/tablecmds.c

@@ -345,6 +345,8 @@ static void ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 					  AlterTableCmd *cmd, LOCKMODE lockmode);
 static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode);
 static void ATPostAlterTypeParse(char *cmd, List **wqueue, LOCKMODE lockmode);
+static void change_owner_fix_column_acls(Oid relationOid,
+							 Oid oldOwnerId, Oid newOwnerId);
 static void change_owner_recurse_to_sequences(Oid relationOid,
 								  Oid newOwnerId, LOCKMODE lockmode);
 static void ATExecClusterOn(Relation rel, const char *indexName, LOCKMODE lockmode);
@@ -7530,6 +7532,14 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lock
 
 		heap_freetuple(newtuple);
 
+		/*
+		 * We must similarly update any per-column ACLs to reflect the new
+		 * owner; for neatness reasons that's split out as a subroutine.
+		 */
+		change_owner_fix_column_acls(relationOid,
+									 tuple_class->relowner,
+									 newOwnerId);
+
 		/*
 		 * Update owner dependency reference, if any.  A composite type has
 		 * none, because it's tracked for the pg_type entry instead of here;
@@ -7586,6 +7596,71 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lock
 	relation_close(target_rel, NoLock);
 }
 
+/*
+ * change_owner_fix_column_acls
+ *
+ * Helper function for ATExecChangeOwner.  Scan the columns of the table
+ * and fix any non-null column ACLs to reflect the new owner.
+ */
+static void
+change_owner_fix_column_acls(Oid relationOid, Oid oldOwnerId, Oid newOwnerId)
+{
+	Relation	attRelation;
+	SysScanDesc scan;
+	ScanKeyData key[1];
+	HeapTuple	attributeTuple;
+
+	attRelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	ScanKeyInit(&key[0],
+				Anum_pg_attribute_attrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(relationOid));
+	scan = systable_beginscan(attRelation, AttributeRelidNumIndexId,
+							  true, SnapshotNow, 1, key);
+	while (HeapTupleIsValid(attributeTuple = systable_getnext(scan)))
+	{
+		Form_pg_attribute att = (Form_pg_attribute) GETSTRUCT(attributeTuple);
+		Datum		repl_val[Natts_pg_attribute];
+		bool		repl_null[Natts_pg_attribute];
+		bool		repl_repl[Natts_pg_attribute];
+		Acl		   *newAcl;
+		Datum		aclDatum;
+		bool		isNull;
+		HeapTuple	newtuple;
+
+		/* Ignore dropped columns */
+		if (att->attisdropped)
+			continue;
+
+		aclDatum = heap_getattr(attributeTuple,
+								Anum_pg_attribute_attacl,
+								RelationGetDescr(attRelation),
+								&isNull);
+		/* Null ACLs do not require changes */
+		if (isNull)
+			continue;
+
+		memset(repl_null, false, sizeof(repl_null));
+		memset(repl_repl, false, sizeof(repl_repl));
+
+		newAcl = aclnewowner(DatumGetAclP(aclDatum),
+							 oldOwnerId, newOwnerId);
+		repl_repl[Anum_pg_attribute_attacl - 1] = true;
+		repl_val[Anum_pg_attribute_attacl - 1] = PointerGetDatum(newAcl);
+
+		newtuple = heap_modify_tuple(attributeTuple,
+									 RelationGetDescr(attRelation),
+									 repl_val, repl_null, repl_repl);
+
+		simple_heap_update(attRelation, &newtuple->t_self, newtuple);
+		CatalogUpdateIndexes(attRelation, newtuple);
+
+		heap_freetuple(newtuple);
+	}
+	systable_endscan(scan);
+	heap_close(attRelation, RowExclusiveLock);
+}
+
 /*
  * change_owner_recurse_to_sequences
  *