Improved error handling in moveAll function

We are now explicit that we os.Rename only if the target directory does
not exist (os.IsNotExist(err)) and we don't do that if it's any other
type of an error. In such case, we return from the function doing
nothing.

We also no longer ignore errors from ioutil.ReadDir. If the error
happens, we return the function doing nothing.

Author: pdyraga

pkg/persistence/disk_persistence.go

@@ -210,25 +210,40 @@ func readAll(directoryPath string) (<-chan DataDescriptor, <-chan error) {
 }
 
 func moveAll(directoryFromPath, directoryToPath string) error {
-	if _, err := os.Stat(directoryToPath); !os.IsNotExist(err) {
-		files, _ := ioutil.ReadDir(directoryFromPath)
-		for _, file := range files {
-			from := fmt.Sprintf("%s/%s", directoryFromPath, file.Name())
-			to := fmt.Sprintf("%s/%s", directoryToPath, file.Name())
-			err := os.Rename(from, to)
-			if err != nil {
-				return err
-			}
-		}
-		err = os.RemoveAll(directoryFromPath)
-		if err != nil {
-			return fmt.Errorf("error occurred while removing archived dir: [%v]", err)
-		}
-	} else {
+	_, err := os.Stat(directoryToPath)
+
+	// target directory does not exist, we can move everything
+	if os.IsNotExist(err) {
 		err := os.Rename(directoryFromPath, directoryToPath)
 		if err != nil {
 			return fmt.Errorf("error occurred while moving a dir: [%v]", err)
 		}
+
+		return nil
+	}
+
+	// unexpected error occurred while checking target directory existence,
+	// returning
+	if err != nil {
+		return fmt.Errorf("could not stat target directory: [%v]", err)
+	}
+
+	// target directory does exit, we need to append files
+	files, err := ioutil.ReadDir(directoryFromPath)
+	if err != nil {
+		return fmt.Errorf("could not read directory [%v]: [%v]", directoryFromPath, err)
+	}
+	for _, file := range files {
+		from := fmt.Sprintf("%s/%s", directoryFromPath, file.Name())
+		to := fmt.Sprintf("%s/%s", directoryToPath, file.Name())
+		err := os.Rename(from, to)
+		if err != nil {
+			return err
+		}
+	}
+	err = os.RemoveAll(directoryFromPath)
+	if err != nil {
+		return fmt.Errorf("error occurred while removing archived dir: [%v]", err)
 	}
 
 	return nil