core: refine condition for using legacy chain freezer directory (#33032)

Author: jsvisa

common/path.go

@@ -37,3 +37,14 @@ func AbsolutePath(datadir string, filename string) string {
 	}
 	return filepath.Join(datadir, filename)
 }
+
+// IsNonEmptyDir checks if a directory exists and is non-empty.
+func IsNonEmptyDir(dir string) bool {
+	f, err := os.Open(dir)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+	names, _ := f.Readdirnames(1)
+	return len(names) > 0
+}

core/rawdb/database.go

@@ -177,7 +177,7 @@ func resolveChainFreezerDir(ancient string) string {
 	// - chain freezer exists in legacy location (root ancient folder)
 	freezer := filepath.Join(ancient, ChainFreezerName)
 	if !common.FileExist(freezer) {
-		if !common.FileExist(ancient) {
+		if !common.FileExist(ancient) || !common.IsNonEmptyDir(ancient) {
 			// The entire ancient store is not initialized, still use the sub
 			// folder for initialization.
 		} else {

node/defaults.go

@@ -22,6 +22,7 @@ import (
 	"path/filepath"
 	"runtime"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/nat"
 	"github.com/ethereum/go-ethereum/rpc"
@@ -90,7 +91,7 @@ func DefaultDataDir() string {
 			// is non-empty, use it, otherwise DTRT and check %LOCALAPPDATA%.
 			fallback := filepath.Join(home, "AppData", "Roaming", "Ethereum")
 			appdata := windowsAppData()
-			if appdata == "" || isNonEmptyDir(fallback) {
+			if appdata == "" || common.IsNonEmptyDir(fallback) {
 				return fallback
 			}
 			return filepath.Join(appdata, "Ethereum")
@@ -113,16 +114,6 @@ func windowsAppData() string {
 	return v
 }
 
-func isNonEmptyDir(dir string) bool {
-	f, err := os.Open(dir)
-	if err != nil {
-		return false
-	}
-	names, _ := f.Readdir(1)
-	f.Close()
-	return len(names) > 0
-}
-
 func homeDir() string {
 	if home := os.Getenv("HOME"); home != "" {
 		return home