I don't think so. `Processor` wants to be called to write into an unmanaged buffer. What we're doing here is giving the managed buffer to libgit2 to copy from.

Well, I guess we could re-use the bit that decides how much to read from the stream and reads that into the managed buffer, but I'm not sure the logic is large or unique enough for it to be worth it (since it's a subtraction and a `min`), and we'd have to create a new common function. I can try if you want to see what it would look like.