core, cmd, trie: fix the condition of pathdb initialization (#28718)

Original problem was caused by #28595, where we made it so that as soon as we start to sync, the root of the disk layer is deleted. That is not wrong per se, but another part of the code uses the "presence of the root" as an init-check for the pathdb. And, since the init-check now failed, the code tried to re-initialize it which failed since a sync was already ongoing.

The total impact being: after a state-sync has begun, if the node for some reason is is shut down, it will refuse to start up again, with the error message: `Fatal: Failed to register the Ethereum service: waiting for sync.`. 

This change also modifies how `geth removedb` works, so that the user is prompted for two things: `state data` and `ancient chain`. The former includes both the chaindb aswell as any state history stored in ancients. 

---------

Co-authored-by: Martin HS <martin@swende.se>

cmd/geth/dbcmd.go

@@ -198,60 +198,73 @@ WARNING: This is a low-level operation which may cause database corruption!`,
 func removeDB(ctx *cli.Context) error {
 	stack, config := makeConfigNode(ctx)
 
-	// Remove the full node state database
-	path := stack.ResolvePath("chaindata")
-	if common.FileExist(path) {
-		confirmAndRemoveDB(path, "full node state database")
-	} else {
-		log.Info("Full node state database missing", "path", path)
-	}
-	// Remove the full node ancient database
-	path = config.Eth.DatabaseFreezer
+	// Resolve folder paths.
+	var (
+		rootDir    = stack.ResolvePath("chaindata")
+		ancientDir = config.Eth.DatabaseFreezer
+	)
 	switch {
-	case path == "":
-		path = filepath.Join(stack.ResolvePath("chaindata"), "ancient")
-	case !filepath.IsAbs(path):
-		path = config.Node.ResolvePath(path)
-	}
-	if common.FileExist(path) {
-		confirmAndRemoveDB(path, "full node ancient database")
-	} else {
-		log.Info("Full node ancient database missing", "path", path)
-	}
-	// Remove the light node database
-	path = stack.ResolvePath("lightchaindata")
-	if common.FileExist(path) {
-		confirmAndRemoveDB(path, "light node database")
-	} else {
-		log.Info("Light node database missing", "path", path)
+	case ancientDir == "":
+		ancientDir = filepath.Join(stack.ResolvePath("chaindata"), "ancient")
+	case !filepath.IsAbs(ancientDir):
+		ancientDir = config.Node.ResolvePath(ancientDir)
 	}
+	// Delete state data
+	statePaths := []string{rootDir, filepath.Join(ancientDir, rawdb.StateFreezerName)}
+	confirmAndRemoveDB(statePaths, "state data")
+
+	// Delete ancient chain
+	chainPaths := []string{filepath.Join(ancientDir, rawdb.ChainFreezerName)}
+	confirmAndRemoveDB(chainPaths, "ancient chain")
 	return nil
 }
 
+// removeFolder deletes all files (not folders) inside the directory 'dir' (but
+// not files in subfolders).
+func removeFolder(dir string) {
+	filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		// If we're at the top level folder, recurse into
+		if path == dir {
+			return nil
+		}
+		// Delete all the files, but not subfolders
+		if !info.IsDir() {
+			os.Remove(path)
+			return nil
+		}
+		return filepath.SkipDir
+	})
+}
+
 // confirmAndRemoveDB prompts the user for a last confirmation and removes the
-// folder if accepted.
-func confirmAndRemoveDB(database string, kind string) {
-	confirm, err := prompt.Stdin.PromptConfirm(fmt.Sprintf("Remove %s (%s)?", kind, database))
+// list of folders if accepted.
+func confirmAndRemoveDB(paths []string, kind string) {
+	msg := fmt.Sprintf("Location(s) of '%s': \n", kind)
+	for _, path := range paths {
+		msg += fmt.Sprintf("\t- %s\n", path)
+	}
+	fmt.Println(msg)
+
+	confirm, err := prompt.Stdin.PromptConfirm(fmt.Sprintf("Remove '%s'?", kind))
 	switch {
 	case err != nil:
 		utils.Fatalf("%v", err)
 	case !confirm:
-		log.Info("Database deletion skipped", "path", database)
+		log.Info("Database deletion skipped", "kind", kind, "paths", paths)
 	default:
-		start := time.Now()
-		filepath.Walk(database, func(path string, info os.FileInfo, err error) error {
-			// If we're at the top level folder, recurse into
-			if path == database {
-				return nil
+		var (
+			deleted []string
+			start   = time.Now()
+		)
+		for _, path := range paths {
+			if common.FileExist(path) {
+				removeFolder(path)
+				deleted = append(deleted, path)
+			} else {
+				log.Info("Folder is not existent", "path", path)
 			}
-			// Delete all the files, but not subfolders
-			if !info.IsDir() {
-				os.Remove(path)
-				return nil
-			}
-			return filepath.SkipDir
-		})
-		log.Info("Database successfully deleted", "path", database, "elapsed", common.PrettyDuration(time.Since(start)))
+		}
+		log.Info("Database successfully deleted", "kind", kind, "paths", deleted, "elapsed", common.PrettyDuration(time.Since(start)))
 	}
 }