Creating Substreams of unknown size
I'm currently trying to parse a file format that uses a number of offsets from positions that are, themselves, offset. According to the documentation, the solution would be substreams - but the problem is that many of these sections do not have a fixed size or terminator. Their length can be calculated based on preexisting information, but this would lead to some very complex and unwieldy calculations. Is there a way to create a substream of unknown size? 

Example: I'm decoding a 3d model format, and one section's length depends on the number of objects, as well as certain flags within the section. Since I can't set the section's size based off something inside the section, how do I position it correctly?