I'm implementing the parsing of the git pack file format as part of the coding challenge:
https://app.codecrafters.io/courses/git/stages/7

It seems the git pack format is a binary file format where each object contains a header followed by a Zlib compressed stream. What's unpleasant one doesn't know the size of the compressed block. Is it possible to get back the underlying stream (with into_inner or get_mut) including the buffer data by ZlibDecoder so that I can carry on reading another object header?