par2py 0.1.0

"par2 Python Utilities"

# Par2Py

MIT Licensed par2 parser / A Python framework for interacting with Par2 files

Par2 is a file format for using Reed-Solomon Coding to perform file recovery operations using “blocks” of recovery data.

#Rationale While working on a QR code based backup solution, I found myself wanting additional redundancy. Which is where Par2 comes in. Par2 is a great system with many advantages:

• Everything is in “packets”, with extremely easy to decode headers.

• Packet headers are easy to find, with their “magic” values ?guaranteed? to only show up there.

• Any amount of padding (including random data) is allowed between packets.

• Provided that enough redundancy exists, a missing file can be completely reconstructed.

To increase the likelihood of file recovery I found myself needing to perform byte alignment on individual packets. There were other reasons as well, but this led to creating a par2 parser, and I decided that it would be worth it as a standalone program.

# References: * [Official Specification](http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html) * [Packet & Header format](https://github.com/Parchive/par2cmdline/blob/master/src/par2fileformat.h) * [“magic” & “type”/”signature” values](https://github.com/Parchive/par2cmdline/blob/master/src/par2fileformat.cpp)

Note that you can recover everything in the second link easily from any “vol…par2” file.

# Other (similar) projects: * [par2ools](https://github.com/jmoiron/par2ools) by Jason Moiron

Copyright (c) 2021 Arthur Moore

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.