getDevices excludes a device for which transferIn request is awaiting

[nisargjhaveri]

Bug Description:

getDevices call using the WebUsb interface does not include a device which was earlier available and has an active transferIn request.

Steps to Reproduce:

1. List devices using getDevices.
2. Filter the relevant device, open and claimInterface
3. Start a transferIn request, don't await.
4. Try to call getDevices again.
5. Notice that the result of the getDevices does not include the device.

Here is a snippet I was able to reproduce this with.

import { WebUSB } from 'usb';

const WebUsbDeviceFilter: USBDeviceFilter = {
    classCode: 0xFF,
    subclassCode: 0x42,
    protocolCode: 1,
};

const usb = new WebUSB({
    "allowAllDevices": true
});

(async () => {
    let devices: USBDevice[];
    devices = await usb.getDevices();

    console.log("Initial device length:", devices.length);

    let device = devices
        .filter(d => {
            return d.configuration?.interfaces.some(iface => {
                return iface.alternate.interfaceClass === WebUsbDeviceFilter.classCode
                    && iface.alternate.interfaceSubclass === WebUsbDeviceFilter.subclassCode
                    && iface.alternate.interfaceProtocol === WebUsbDeviceFilter.protocolCode
            });
        })[0];

    await device.open();

    let inEndpointNumber, outEndpointNumber;
    for (const configuration of device.configurations) {
        for (const interface_ of configuration.interfaces) {
            for (const alternate of interface_.alternates) {
                if (alternate.interfaceClass === WebUsbDeviceFilter.classCode &&
                    alternate.interfaceSubclass === WebUsbDeviceFilter.subclassCode &&
                    alternate.interfaceProtocol === WebUsbDeviceFilter.protocolCode) {
                    if (device.configuration?.configurationValue !== configuration.configurationValue) {
                        await device.selectConfiguration(configuration.configurationValue);
                    }

                    if (!interface_.claimed) {
                        await device.claimInterface(interface_.interfaceNumber);
                    }

                    if (interface_.alternate.alternateSetting !== alternate.alternateSetting) {
                        await device.selectAlternateInterface(interface_.interfaceNumber, alternate.alternateSetting);
                    }

                    for (const endpoint of alternate.endpoints) {
                        switch (endpoint.direction) {
                            case 'in':
                                inEndpointNumber = endpoint.endpointNumber;
                                break;
                            case 'out':
                                outEndpointNumber = endpoint.endpointNumber;
                                break;
                        }
                    }
                }
            }
        }
    }

    // devices = await usb.getDevices();
    // console.log("Before transferIn:", devices.length);

    device.transferIn(inEndpointNumber, 24);

    devices = await usb.getDevices();
    console.log("After transferIn:", devices.length);
})();

Output:

Initial device length: 7
After transferIn: 6

Additional Information

• Operating System: macOS Ventura (13.1)
• Runtime (node -v or electron -v): node v16.16.0
• Node USB Version (npm ls usb): usb@2.6.0

[nisargjhaveri]

Also, calling getDevices just before transferIn call makes the transferIn call fail with the below error.

./node_modules/usb/dist/webusb/webusb-device.js:431
                        throw new Error("transferIn error: " + error_7);
                              ^

Error: transferIn error: TypeError: Cannot read properties of undefined (reading 'transfer')
    at WebUSBDevice.<anonymous> (./node_modules/usb/dist/webusb/webusb-device.js:431:31)
    at step (./node_modules/usb/dist/webusb/webusb-device.js:33:23)
    at Object.next (./node_modules/usb/dist/webusb/webusb-device.js:14:53)
    at ./node_modules/usb/dist/webusb/webusb-device.js:8:71
    at new Promise (<anonymous>)
    at __awaiter (./node_modules/usb/dist/webusb/webusb-device.js:4:12)
    at WebUSBDevice.transferIn (./node_modules/usb/dist/webusb/webusb-device.js:404:16)
    at ./dist/client/trial.js:68:12
    at Generator.next (<anonymous>)
    at fulfilled (./dist/client/trial.js:5:58)

[nisargjhaveri]

Looks like this is likely because of the fact that getDevices call creates new instances of the device and does not return the same instance when called again. Created PR #567 to address this.

[nisargjhaveri]

This should not be fixed in master since #567 was merged.

@thegecko, Curious: What is the release cycle we're following? When should I expect a version that includes the fix for this?

[thegecko]

It's building now

[nisargjhaveri]

That's quick! Thanks a lot! :)

[thegecko]

https://github.com/node-usb/node-usb/releases/tag/v2.7.0 https://www.npmjs.com/package/usb/v/2.7.0