The VFS

The virtual file system(VFS) is one of the most important parts of the operating system. It handles communication with permanent storage. In our case the VFS doesn't handle the file operation them selves but requires the file system to give us function pointers to work with.

A file in our VFS is nothing more than a data structure with a pointer to the file system driver file, which itself is attached to one of the permanent storage devices. This might seem complex but it does provide us with a whole lot of possibilities, which are provided not only by our system but also by others like Linux and BSD.

The file system mounts still have to be written though so I still can't go too deep into the implementation details of those.

One thing we already have working though is a special kind of file we call a buffer. When we open a file with the initialiser function of the buffer it loads all of its functions into the function pointers of the buffer and now allows us to read from, write to, seek in and close the buffer like it's a normal file somewhere on a disk. Internally it keeps all the data in the form of a tree and when it's time to close the buffer, while no other part of the application has opened it, it will remove all of it, which is quite unlike a normal file.

Because of the index variable, which is 64 bits, the buffer supports files of up to 16.000 PiB. If you don't know what that means. Well, lets just say that it's plenty for the coming decade if not more (I personally have trouble filling my 320 GiB, and that's roughly 0.002% of the buffer …).