Island: Wrap directory traversal errors in repository errors

A given `IFileRepository` may have no concept of directories.
`LocalStorageFileRepository` should wrap the ValueErrors raised to
prevent directory traversal in repository errors.

monkey/monkey_island/cc/repository/file_storage/i_file_repository.py

@@ -20,7 +20,6 @@ class IFileRepository(metaclass=abc.ABCMeta):
 
         :param unsafe_file_name: An unsanitized file name that will identify the file
         :param file_contents: The data to be stored in the file
-        :raises ValueError: If the file name is an attempted directory traversal
         :raises StorageError: If an error was encountered while attempting to store the file
         """
         pass
@@ -34,7 +33,6 @@ class IFileRepository(metaclass=abc.ABCMeta):
         :return: A file-like object providing access to the file's contents
         :raises FileNotFoundError: if the file does not exist
         :raises RetrievalError: if the file exists but cannot be retrieved
-        :raises ValueError: If the file name is an attempted directory traversal
         """
         pass
 
@@ -47,7 +45,6 @@ class IFileRepository(metaclass=abc.ABCMeta):
         idempotent and will succeed if the file to be deleted does not exist.
 
         :param unsafe_file_name: An unsanitized file name that identifies the file to be deleted
-        :raises ValueError: If the file name is an attempted directory traversal
         :raises RemovalError: If an error was encountered while attempting to remove a file
         """
         pass

monkey/monkey_island/cc/repository/file_storage/local_storage_file_repository.py

@@ -32,19 +32,19 @@ class LocalStorageFileRepository(IFileRepository):
         self._storage_directory = storage_directory
 
     def save_file(self, unsafe_file_name: str, file_contents: BinaryIO):
+        try:
             safe_file_path = self._get_safe_file_path(unsafe_file_name)
 
             logger.debug(f"Saving file contents to {safe_file_path}")
-        try:
             with open(safe_file_path, "wb") as dest:
                 shutil.copyfileobj(file_contents, dest)
         except Exception as err:
             raise StorageError(f"Error while attempting to store {unsafe_file_name}: {err}")
 
     def open_file(self, unsafe_file_name: str) -> BinaryIO:
+        try:
             safe_file_path = self._get_safe_file_path(unsafe_file_name)
 
-        try:
             logger.debug(f"Opening {safe_file_path}")
             return open(safe_file_path, "rb")
         except FileNotFoundError as err:
@@ -58,9 +58,9 @@ class LocalStorageFileRepository(IFileRepository):
             )
 
     def delete_file(self, unsafe_file_name: str):
+        try:
             safe_file_path = self._get_safe_file_path(unsafe_file_name)
 
-        try:
             logger.debug(f"Deleting {safe_file_path}")
             safe_file_path.unlink()
         except FileNotFoundError: