Ah, but are /dev/input entries reusable?

Let's say you have /dev/input/event{0,10}, event5 is a USB keyboard, you unplug it, I assume event5 goes away.

But then you plug in a controller, does this get mapped to event11, or does event5 get reused? Is the behaviour reliable in all versions of linux?

You might argue that metadata should do the trick, but in my experience, on device files, anything beyond read/write is a crapshoot, whether metadata makes any sense is basically a roll of the dice.

So if you have to open device files in order to check their identity, you might as well skip the identity bit and just check if you're a gamepad.

edit: per charcircuit's comment below, it looks like the metadata of /dev/input at least are considered reliable, and this was used to mitigate the issue by checking the mtime of /dev/input itself against a stored timestamp: https://github.com/spurious/SDL-mirror/commit/59728f9802c786...