Question

I am looking to create a file by structuring it in size blocks. Essentially I am looking to create a rudimentary file system.

I need to write a header, and then an “infinite” possible number of entries of the same size/structure. The important parts are:

• Each block of data needs to be read/writable individually
• Header needs to be readable/writable as its own entity
• Need a way to store this data and be able to determine its location in the file quickly

The would imagine the file would resemble something like:

[HEADER][DATA1][DATA2][DATA3][...]

What is the proper way to handle something like this? Lets say I want to read DATA3 from the file, how do I know where that data chunk starts?

Answer 1

If I understand you correctly and you need a way to assign a kind of names/IDs to your DATA chunks, you can try to introduce yet another type of chunk.

Let’s call it TOC (table of contents).
So, the file structure will look like [HEADER][TOC1][DATA1][DATA2][DATA3][TOC2][...].

TOC chunk will contain names/IDs and references to multiple DATA chunks. Also, it will contain some internal data such as pointer to the next TOC chunk (so, you might consider each TOC chunk as a linked-list node).

At runtime all TOC chunks could be represented as a kind of HashMap, where key is a name/ID of the DATA chunk and value is its location in the file.