core/rawdb: fix underflow in freezer inspect for empty ancients

core/rawdb/ancient_utils.go

@@ -31,15 +31,11 @@
 
 // freezerInfo contains the basic information of the freezer.
 type freezerInfo struct {
-	name  string      // The identifier of freezer
-	head  uint64      // The number of last stored item in the freezer
-	tail  uint64      // The number of first stored item in the freezer
-	sizes []tableSize // The storage size per table
-}
-
-// count returns the number of stored items in the freezer.
-func (info *freezerInfo) count() uint64 {
-	return info.head - info.tail + 1
+	name     string      // The identifier of freezer
+	head     uint64      // The number of last stored item in the freezer, valid only if ancients > 0
+	tail     uint64      // The number of first stored item in the freezer
+	count    uint64      // The number of stored items in the freezer
+	sizes    []tableSize // The storage size per table
 }
 
 // size returns the storage size of the entire freezer.
@@ -65,14 +61,24 @@
 	if err != nil {
 		return freezerInfo{}, err
 	}
-	info.head = ancients - 1
+	info.ancients = ancients
+	if ancients > 0 {
+		info.head = ancients - 1
+	} else {
+		info.head = 0
+	}
 
 	// Retrieve the number of first stored item
 	tail, err := reader.Tail()
 	if err != nil {
 		return freezerInfo{}, err
 	}
 	info.tail = tail
+	if ancients == 0 {
+		info.count = 0
+	} else {
+		info.count = info.head - info.tail + 1
+	}
 	return info, nil
 }
 

core/rawdb/database.go

@@ -644,7 +644,7 @@ func InspectDatabase(db ethdb.Database, keyPrefix, keyStart []byte) error {
 				fmt.Sprintf("Ancient store (%s)", strings.Title(ancient.name)),
 				strings.Title(table.name),
 				table.size.String(),
-				fmt.Sprintf("%d", ancient.count()),
+				fmt.Sprintf("%d", ancient.count),
 			})
 		}
 		total.Add(uint64(ancient.size()))