maestral.utils.hashing
======================

.. py:module:: maestral.utils.hashing

.. autoapi-nested-parse::

   Module for content hashing file contents.





Module Contents
---------------

.. py:class:: DropboxContentHasher

   Computes a hash using the same algorithm that the Dropbox API uses for the
   "content_hash" metadata field.

   The :meth:`digest` method returns a raw binary representation of the hash.  The
   :meth:`hexdigest` convenience method returns a hexadecimal-encoded version, which
   is what the "content_hash" metadata field uses.

   This class has the same interface as the hashers in the standard 'hashlib' package.

   :Example:

       Read a file in chunks of 1024 bytes and compute its content hash:

       >>> hasher = DropboxContentHasher()
       >>> with open('some-file', 'rb') as f:
       ...     while True:
       ...         chunk = f.read(1024)
       ...         if len(chunk) == 0:
       ...             break
       ...         hasher.update(chunk)
       ... print(hasher.hexdigest())



   .. py:attribute:: BLOCK_SIZE


   .. py:method:: update(new_data)


   .. py:method:: digest()


   .. py:method:: hexdigest()


   .. py:method:: copy()


.. py:class:: StreamHasher(f, hasher)

   A wrapper around a file-like object (either for reading or writing)
   that hashes everything that passes through it.  Can be used with
   DropboxContentHasher or any 'hashlib' hasher.

   :Example:

       >>> hasher = DropboxContentHasher()
       >>> with open('some-file', 'rb') as f:
       ...     wrapped_f = StreamHasher(f, hasher)
       ...     response = some_api_client.upload(wrapped_f)
       >>> locally_computed = hasher.hexdigest()
       >>> assert response.content_hash == locally_computed

   :param f: File-like object.
   :param hasher: Hasher to use. Must implement an ``update`` method.


   .. py:method:: close()


   .. py:method:: flush()


   .. py:method:: fileno()


   .. py:method:: tell()


   .. py:method:: read(size = -1)


   .. py:method:: write(b)


   .. py:method:: readline(size = -1)


   .. py:method:: readlines(hint = -1)