Compute and apply signature-based file differences using a rolling hash algorithm

Rolling hash algorithm diff lib

The library rsync (is called rsync because I'm bad at choosing names) permit to apply patch to files calculating a delta file to apply. This library could be used to send only the diff file instead of the complete file to update a remote storage or use less space in a backup system.

The tipical application is a backup machine B that has stored a file "foo.bin" vers. 1.0, a remote machine A have modified file "foo.bin" that now is vers. 2.0 B generate signature of file "foo.bin"(1.0) and send to machine A, A compute the difference with vers. 2.0 and send the delta file to B. B apply the delto to recreate a "foo.bin" vers 2.0

I used IStream and OStream to permit to users to reimplement and provide a different IO accesss.

Note

Please look at the test test_rsync.cpp and test_delta.cpp for the assignement

What is missing

• Use of Cmake
• block_size has to be set in IStream, better an argument for rsync functions
• remove IStream/OStream (mock and file derived class also) and use STL istream/ostream
• Create a file from Delta class
• complete the RollingHashDiff application parsing argument and usign rsync library
• a better rolling hash algorithm
• use a better container for byte read from stream (a circular buffer ?)

Requirements

• Visual Studio 2022