init: raise error when overwriting old database

cmd/nitro/init.go

@@ -294,6 +294,14 @@ func dirExists(path string) bool {
 	return info.IsDir()
 }
 
+func databaseEmpty(path string) bool {
+	entries, err := os.ReadDir(path)
+	if err != nil {
+		return true
+	}
+	return len(entries) == 0 || (len(entries) == 1 && entries[0].Name() == "LOCK")
+}
+
 func openInitializeChainDb(ctx context.Context, stack *node.Node, config *NodeConfig, chainId *big.Int, cacheConfig *core.CacheConfig, persistentConfig *conf.PersistentConfig, l1Client arbutil.L1Interface, rollupAddrs chaininfo.RollupAddresses) (ethdb.Database, *core.BlockChain, error) {
 	if !dirExists(path.Join(stack.InstanceDir(), "l2chaindata")) {
 		const errorFmt = "database was not found in %s, but it was found in %s (have you placed the database in the wrong directory?)"
@@ -305,11 +313,7 @@ func openInitializeChainDb(ctx context.Context, stack *node.Node, config *NodeCo
 		if dirExists(path.Join(grandParentDir, "l2chaindata")) {
 			return nil, nil, fmt.Errorf(errorFmt, stack.InstanceDir(), grandParentDir)
 		}
-		entries, err := os.ReadDir(stack.InstanceDir())
-		if err != nil {
-			return nil, nil, fmt.Errorf("failed to open database directory: %w", err)
-		}
-		if len(entries) > 1 || (len(entries) == 1 && entries[0].Name() != "LOCK") {
+		if !databaseEmpty(stack.InstanceDir()) {
 			return nil, nil, fmt.Errorf("found unexpected files in database directory '%s' (have you set --persistent.chain and --persistent.global-config correctly? If so, delete the database directory and try again)", stack.InstanceDir())
 		}
 	}
@@ -354,6 +358,10 @@ func openInitializeChainDb(ctx context.Context, stack *node.Node, config *NodeCo
 		}
 	}
 
+	if !databaseEmpty(stack.InstanceDir()) {
+		return nil, nil, fmt.Errorf("trying to overwrite old database directory '%s' (delete the database directory and try again)", stack.InstanceDir())
+	}
+
 	initFile, err := downloadInit(ctx, &config.Init)
 	if err != nil {
 		return nil, nil, err