Ebiten: panic while accessing gamepadButtonDurations

[tslocum]

The following error occurs when running a blank application (nothing drawn/updated) on the latest master (likely caused by c95049b).

panic: runtime error: index out of range [32] with length 32

goroutine 5 [running]:
github.com/hajimehoshi/ebiten/inpututil.(*inputState).update(0xb50f20)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/inpututil/inpututil.go:122 +0xdc6
github.com/hajimehoshi/ebiten/inpututil.init.0.func1(0x0, 0x0)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/inpututil/inpututil.go:64 +0x2d
github.com/hajimehoshi/ebiten/internal/hooks.RunBeforeUpdateHooks(0x0, 0x0)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/internal/hooks/hooks.go:38 +0xb8
github.com/hajimehoshi/ebiten.(*uiContext).update(0xb50d20, 0x0, 0x0)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/uicontext.go:287 +0xe7
github.com/hajimehoshi/ebiten.(*uiContext).Update(0xb50d20, 0xc00005de10, 0x8d0000)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/uicontext.go:241 +0xaa
github.com/hajimehoshi/ebiten/internal/uidriver/glfw.(*UserInterface).update(0xb132e0, 0x20001, 0x1)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/internal/uidriver/glfw/ui.go:816 +0x266
github.com/hajimehoshi/ebiten/internal/uidriver/glfw.(*UserInterface).loop(0xb132e0, 0x0, 0x0)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/internal/uidriver/glfw/ui.go:862 +0xcb
github.com/hajimehoshi/ebiten/internal/uidriver/glfw.(*UserInterface).run(0xb132e0, 0x0, 0x0)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/internal/uidriver/glfw/ui.go:731 +0x2e4
github.com/hajimehoshi/ebiten/internal/uidriver/glfw.(*UserInterface).Run.func1(0xc000098410, 0xc0000b4180, 0xb132e0)
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/internal/uidriver/glfw/ui.go:568 +0x6b
created by github.com/hajimehoshi/ebiten/internal/uidriver/glfw.(*UserInterface).Run
    /home/trevor/go/pkg/mod/github.com/hajimehoshi/[email protected]/internal/uidriver/glfw/ui.go:565 +0x17b

[tslocum]

Sorry for the noise, I have found that this panic was my fault and not ebiten's. (I initialized two games)

[tslocum]

Hmmmm, I still seem to be encountering this after resolving other issues. You can reproduce this by running gitlab.com/tslocum/venture/cmd/venturedemo.

[hajimehoshi]

I'll take a look.

CC @seebs

[hajimehoshi]

What kind of gamepad are you using now?

[tslocum]

Thanks. I don't have any gamepads connected. And in case it helps this is was encountered on Gentoo Linux + Sway (Wayland).

[hajimehoshi]

The error indicates that ebiten.GamepadIDs() returns a slice of IDs, which indicates there is a gamepad on your machine. That's pretty odd. Could you try ebiten.GamepadIDs() and see what IDs are there?

[hajimehoshi]

I tested the app on macOS and could not reproduce the same error.

[seebs]

This is odd, because the max gamepad button ID in the code is 31, so I was assuming that [32] would be right?

[hajimehoshi]

I think getting the number of the gamepad buttons returns >32. This might be an issue in GLFW.

[tslocum]

Thanks. ebiten.GamepadIDs() returns an empty slice on my machine when added to the above demo.

[seebs]

okay, looking at it, there's at least something in my code which is probably logically-wrong:

        n := ebiten.GamepadButtonNum(id)

this isn't capped in any way as being less than the listed Max, so. I'll send a possible patch, but since I can't reproduce the failure myself yet, I don't know whether it's sane.

[hajimehoshi]

Thanks. ebiten.GamepadIDs() returns an empty slice on my machine when added to the above demo.

Thanks. If so, inpututil.go:122 should never be reached. Am I missing something? 🤔

[hajimehoshi]

So, I was wondering whether ebiten.GamepadIDs() is deterministic and always 0 or not.

[cesys]

Found the same bug when running on windows.

[hajimehoshi]

Yeah, I know how to suppress the error. My question is why a gamepad is detected even though there is no actual gamepad device.

[hajimehoshi]

@cesys So, have you reproduced the same error without a gamepad?

[cesys]

In my case, there was no gamepad active (they were all not paired) but I have XBox controllers paired with my Windows (again turned off when I ran the test). I wonder if they are detected as gamepads because the receiver is actually plugged in the USB port or that's because of another device I have plugged that is seen as a gamepad. Not sure.

[hajimehoshi]

I see. Even though the XBox gamepad is connected, I don't think the XBox gamepad has more than 32 buttons. Actually the screenshot says n = 1085 buttons, right?

[cesys]

Yeah definitely not 32 buttons. No idea why we get 1085 (either a bug triggered by some peripherals I have or a weird value returned by some peripheral I have). However, adding that check in this specific case should be good anyway and should fix this problem

[hajimehoshi]

Thanks. Before patching this, I'd like to check whether the root cause was in Ebiten or in GLFW. If GLFW is the cause (and I think this is true but am not sure yet), I'd be happy to patch this.

[hajimehoshi]

The same issue is reported by another person. I'll take a look...

[hajimehoshi]

https://github.com/glfw/glfw/issues/924 Related?

[hajimehoshi]

My guess is that there are some devices that are not joysticks but recognized as joysticks by GLFW.

[hajimehoshi]

I think this was fixed.

@tslocum , @cesys Could you test when you are available? Thanks!

[hajimehoshi]

Ripolak from OpenDiablo 2 Discord tested this and confirmed this was fixed.