🐹 🐛 fix cachedirectory.go to reuse empty dir

For the cases of cache directories that need to exist before, the code fails with the error message that it can't create the directory. For example, cache dir from github workflows.

This code change makes sure to verify the cases if it's empty or not.

Author: marcellodesales

internal/cachedirectory/cachedirectory.go

@@ -27,24 +27,37 @@ func NewCacheDirectory(path string) CacheDirectory {
 	}
 }
 
-func isEmptyOrNonExistentDirectory(path string) (bool, error) {
-	f, err := os.Open(path)
+func isAccessibleDirectory(path string) (bool, error) {
+	_, err := os.Stat(path)
+
 	if err != nil {
 		if os.IsNotExist(err) {
-			return true, nil
+			return false, nil
 		}
 		return false, errors.Wrapf(err, "Could not access directory %s.", path)
 	}
-	defer f.Close()
+	
+	return true, nil
+}
 
-	_, err = f.Readdirnames(1)
+func isEmptyDirectory(path string) (bool, error) {
+	files, err := ioutil.ReadDir(path)
 	if err != nil {
-		if err == io.EOF {
-			return true, nil
-		}
 		return false, errors.Wrapf(err, "Could not read contents of directory %s.", path)
 	}
-	return false, nil
+
+	return len(files) == 0, nil
+}
+
+func existsDirectory(path string) (bool, error) {
+	_, err := os.Stat(path)
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+	if err != nil {
+		return false, errors.Wrapf(err, "Could not access directory %s.", path)
+	}
+	return true, nil
 }
 
 func (cacheDirectory *CacheDirectory) CheckOrCreateVersionFile(pull bool, version string) error {
@@ -77,20 +90,37 @@ func (cacheDirectory *CacheDirectory) CheckOrCreateVersionFile(pull bool, versio
 			}
 		}
 
-		isEmptyOrNonExistent, err := isEmptyOrNonExistentDirectory(cacheDirectory.path)
+		existsDirectory, err := existsDirectory(cacheDirectory.path)
 		if err != nil {
 			return err
 		}
-		if isEmptyOrNonExistent {
+		if !existsDirectory {
 			err := os.Mkdir(cacheDirectory.path, 0755)
 			if err != nil {
 				return errors.Wrap(err, "Could not create cache directory.")
 			}
-			err = ioutil.WriteFile(cacheVersionFilePath, []byte(version), 0644)
+
+		} else {
+			isAccessible, err := isAccessibleDirectory(cacheDirectory.path)
+			if err != nil {
+				return err
+			}
+			if !isAccessible {
+				return errors.Wrap(err, "Cache dir exists, but the current user can't write to it.")
+			}
+
+			isEmpty, err := isEmptyDirectory(cacheDirectory.path)
 			if err != nil {
-				return errors.Wrap(err, "Could not create cache version file.")
+				return err
+			}
+			if isEmpty {
+				err = ioutil.WriteFile(cacheVersionFilePath, []byte(version), 0644)
+				if err != nil {
+					return errors.Wrap(err, "Could not create cache version file.")
+				}
 			}
 			return nil
+			
 		}
 		return usererrors.New(errorNotACacheOrEmpty)
 	}