git-rehash

Rewrite git objects to map them between hash spaces.

git objects are identified by a SHA1 hash of their type, length, and content [[1] masak]. By mapping the objects into a different hash space, we can store git objects in other content-addressable file systems and sync them with git's object storage.

This module rewrites git objects to preserve links between them while moving the objects into a different hash space. Blobs (git objects that store file data) are passed through without rewriting, so they will hash the same as if you hash the original files in the repo.

API

This module uses pull-streams.

git objects are represented by an object with the following properties:

• type: the type of the object, one of ["tag", "commit", "tree", "blob"]
• length: the size in bytes of the object
• read: readable stream of the object's data. This has to be drained before the git object stream can read the next object.

rehash.fromGit(algorithm, lookup(gitHash, cb(err, hash))

Create a through stream for git objects that rewrites their hashes to use algorithm.

• algorithm: a string that may be passed to crypto.createHash, e.g. "sha256"
• lookup: a function for looking up the algorithm-hash of a git object, given the objects's git hash. This is needed for rewriting links to objects that are not present in the stream that rehash is processing.

rehash.toGit()

Create a through stream for git objects that rewrites their hashes from algorithm back to git's native hashing algorithm. This undoes a transformation applied by rehash.fromGit

License

Copyright (c) 2016 Charles Lehner

Usage of the works is permitted provided that this instrument is retained with the works, so that any entity that uses the works is notified of this instrument.

DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.