Ability to access mounted CD images via XHR

[fallenoak]

Howdy!

I'm hunting for a way to use ranged HTTP requests via XHR as a means to let em-dosbox access CD images from a local network endpoint without forcing a browser to download the entire image.

I know this touches on several things, including the fact that DOSBox's cdrom logic works with sync file access, and sync XHR on the main thread of a browser is deprecated / unavailable.

Now that SharedArrayBuffer and OffscreenCanvas are close to reality, I suppose some combination of them might support moving em-dosbox over to a web worker and permit using sync XHR there, while not blocking the main browser thread.

Any thoughts on what would need to be done to make something like this work?

Alternatively, would it be possible to rewrite the cdrom logic in DOSBox to permit this type of access?

I'd be happy to take a stab at it, but looking for a bit of guidance first.

PS Thanks for putting together em-dosbox -- I've been playing around with it for the past week and am floored at how well it works.