pyrsync

pyrsync is a Python module which implements the rsync algorithm, written in pure Python. It is not a wrapper for rsync, but a set of functions which apply full rsync functionality through Python.

The original rsync specification calls for the use of an MD5 hash, which the developers of this module considers to be outdated, and thus all occurences of MD5 have been replaced with SHA256. Personally, I would opt for using SHA512, but this would double the storage size for hash table databases. SHA256 is sufficient to meet standard security requirements for verification processes as of this release, although, eventually, added functionality for the user/developer to choose between various hashes should be considered for further releases.

The majority of the code for this module is taken from Eric Pruitt's post at ActiveState. It was orginally licensed under an MIT license, and this license has been kept wthout modifications.

Installation

If you have setuptools installed, simply do:

$ sudo python setup.py install

If you do not have setuptools, the setup.py script will detect this and default to using the python builtin distutils. To install using distutils, the installation process is the same as documented above for setuptools.

Use

An example use case for this module:

# On the system containing the file that needs to be patched
>>> import pyrsync
>>> unpatched = open("unpatched.file", "rb")
>>> hashes = pyrsync.blockchecksums(unpatched)

# On the remote system after having received hashes
>>> import pyrsync
>>> patchedfile = open("patched.file", "rb")
>>> delta = pyrsync.rsyncdelta(patchedfile, hashes)

# System with the unpatched file after receiving delta
>>> unpatched.seek(0)
>>> save_to = open("locally-patched.file", "wb")
>>> pyrsync.patchstream(unpatched, save_to, delta)