Known implementations

[muliyul]

Is there a section with known implementations for this? (*Manager classes?)

[slonopotamus]

See https://github.com/bozaro/git-as-svn/tree/master/src/main/kotlin/svnserver/ext/gitlfs/server

[muliyul]

I want to use this for s3 storage but not sure how to go about this.

[muliyul]

@slonopotamus What is the "object hash" I need to pass to the client in order to download a blob? Is it the hash of the content? hash of the commit?

[slonopotamus]

It's the hash of LFS object from pointer file.

So if you have, for example, this file:

version https://git-lfs.github.com/spec/v1
oid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393
size 12345

Then hash is 4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393.

You can use ru.bozaro.gitlfs.pointer.Pointer#parsePointer and ru.bozaro.gitlfs.pointer.Pointer#serializePointer to save/load pointer files.

So, the whole procedure is something like this (plus various error handling):

val OID_PREFIX = "sha256:"

val bytes = ...; // Read pointer file from somewhere
val lfsClient = ...; // Construct client

val pointer = Pointer.parsePointer(bytes, 0, length)!!
val oid = pointer[Constants.OID]
val size = pointer[Constants.SIZE].toLong()
val hash: String = oid.substring(OID_PREFIX.length)

val dataStream = lfsClient.openObject(hash)