dump store contents when corrupted file detected

adds Dump to store interface which returns the raw contents of the store in string format
if the store is empty or not readable it returns an error
adds to a ut to check that dump effectively prints the contents of the store

Author: QxBytes

network/manager.go

@@ -204,6 +204,12 @@ func (nm *networkManager) restore(isRehydrationRequired bool) error {
 		} else if errors.As(err, &syntaxErr) {
 			// if null chars detected or failed to parse, state is unrecoverable; delete it
 			logger.Error("Failed to parse corrupted state, deleting", zap.Error(err))
+			contents, readErr := nm.store.Dump()
+			if readErr != nil {
+				logger.Error("Could not read corrupted state", zap.Error(readErr))
+			} else {
+				logger.Info("Logging state", zap.String("stateFile", contents))
+			}
 			nm.store.Remove()
 			return errors.Wrap(err, "failed to parse corrupted state")
 		} else {

store/json.go

@@ -70,30 +70,10 @@ func (kvs *jsonFileStore) Read(key string, value interface{}) error {
 
 	// Read contents from file if memory is not in sync.
 	if !kvs.inSync {
-		// Open and parse the file if it exists.
-		file, err := os.Open(kvs.fileName)
+		b, err := kvs.readBytes()
 		if err != nil {
-			if os.IsNotExist(err) {
-				return ErrKeyNotFound
-			}
 			return err
 		}
-		defer file.Close()
-
-		b, err := io.ReadAll(file)
-		if err != nil {
-			return err
-		}
-
-		if len(b) == 0 {
-			if kvs.logger != nil {
-				kvs.logger.Info("Unable to read empty file", zap.String("fileName", kvs.fileName))
-			} else {
-				log.Printf("Unable to read file %s, was empty", kvs.fileName)
-			}
-
-			return ErrStoreEmpty
-		}
 
 		// Decode to raw JSON messages.
 		if err := json.Unmarshal(b, &kvs.data); err != nil {
@@ -265,3 +245,44 @@ func (kvs *jsonFileStore) Remove() {
 	}
 	kvs.Mutex.Unlock()
 }
+
+func (kvs *jsonFileStore) Dump() (string, error) {
+	kvs.Mutex.Lock()
+	defer kvs.Mutex.Unlock()
+
+	b, err := kvs.readBytes()
+	if err != nil {
+		return "", err
+	}
+
+	return string(b), nil
+}
+
+func (kvs *jsonFileStore) readBytes() ([]byte, error) {
+	// Open and parse the file if it exists.
+	file, err := os.Open(kvs.fileName)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return []byte{}, ErrKeyNotFound
+		}
+		return []byte{}, errors.Wrap(err, "could not open file")
+	}
+	defer file.Close()
+
+	b, err := io.ReadAll(file)
+	if err != nil {
+		return []byte{}, errors.Wrap(err, "could not read file")
+	}
+
+	if len(b) == 0 {
+		if kvs.logger != nil {
+			kvs.logger.Info("Unable to read empty file", zap.String("fileName", kvs.fileName))
+		} else {
+			log.Printf("Unable to read file %s, was empty", kvs.fileName)
+		}
+
+		return []byte{}, ErrStoreEmpty
+	}
+
+	return b, nil
+}

store/json_test.go

@@ -129,6 +129,14 @@ func TestKeyValuePairsAreWrittenAndReadCorrectly(t *testing.T) {
 		t.Fatalf("Failed to create KeyValueStore %v\n", err)
 	}
 
+	defer os.Remove(testFileName)
+
+	// Dump empty store.
+	_, err = kvs.Dump()
+	if err == nil {
+		t.Fatal("Expected store to be empty")
+	}
+
 	// Write a key value pair.
 	err = kvs.Write(testKey1, &writtenValue)
 	if err != nil {
@@ -153,8 +161,17 @@ func TestKeyValuePairsAreWrittenAndReadCorrectly(t *testing.T) {
 			testKey1, readValue, testKey1, writtenValue)
 	}
 
-	// Cleanup.
-	os.Remove(testFileName)
+	// Dump populated store.
+	val, err := kvs.Dump()
+	if err != nil {
+		t.Fatalf("Failed to dump store %v", err)
+	}
+	val = strings.ReplaceAll(val, " ", "")
+	val = strings.ReplaceAll(val, "\t", "")
+	val = strings.ReplaceAll(val, "\n", "")
+	if val != `{"key1":{"Field1":"test","Field2":42},"key2":{"Field1":"any","Field2":14}}` {
+		t.Errorf("Dumped data not expected: %v", val)
+	}
 }
 
 // test case for testing newjsonfilestore idempotent

store/mockstore.go

@@ -71,3 +71,7 @@ func (ms *mockStore) GetLockFileName() string {
 }
 
 func (ms *mockStore) Remove() {}
+
+func (ms *mockStore) Dump() (string, error) {
+	return fmt.Sprintf("%+v", ms.data), nil
+}

store/store.go

@@ -18,6 +18,7 @@ type KeyValueStore interface {
 	Unlock() error
 	GetModificationTime() (time.Time, error)
 	Remove()
+	Dump() (string, error)
 }
 
 var (