# Parscavenger

Parscavenger is a program to aid in the recovery of par2-protected data sets by incorporating data from other sources.

It doesn't do any super-math with the actual parity information. It just uses the hash values to tidy up what data it can. Feed it with a par2 file from which to get hashes, and whatever garbage data you can hope to recover something from.

Give it corrupted files, disk images that might contain the files, incomplete downloads from other sources, earlier or later versions of the same files. Give it a .par2 file with which to search for and assemble this fragmentary data. Out of it will come, if not a complete set of data, at least a set of files with the correct name and with the available data correctly placed within them. This is a suitable input for other utilities.

The mechanism by which is does this is very simple. It's just a brute-force search of the input data for any chunks that match the length and hash specified within the par2 file.

The original purpose of this was dealing with a collection of media I had stored on DVDs which had degraded. I anticipated the unreliability of optical media and burned 10% redundency on them, but sometimes this wasn't enough and I had to patch the data up from other sources.

=> parscavenger.png Basic data flow diagram.
=> parscavender.tar.gz Source