Support stable serial device IDs on linux and maybe netbsd?

[DanielJoyce]

Many linux distros support /dev/serial/by-id which is stable on device plug/unplug. It would be nice to support this as well when enumerating devices.

[de-vri-es]

Hey! It could be nice indeed. The only thing I'm considering is how to structure the API.

Should the current API simply be adjusted to add stable devices? Or should it be a separate new API? Should that one also include devices that don't have a stable device path?

And I think that directory is populated by udev. What about systems that don't have that directory? Should we fall back to non-stable device paths?

[bofh69]

For USB serial ports it is also possible to get stable names on macOS. A former colleague wrote this code in a script:

    ioreg -r -c IOUSBHostDevice -l -n "USB Device Name Here" | \
    grep -w 'IODialinDevice' | \
    awk -F'=' '{print $2}'| \
    sed -E -e 's/[ "]//g' | \
    sort | \
    head -n 1 | \
    tr -d '\n'

I don't have a modern mac so I can't really help with that though.

Anyway, I would go for a new API for this, returning a Result<Vec<(PathBuf, Option<String>)>>.

With the first being a normal "/dev/ttyACMx"/"COM0"/"/dev/ttyusb.123" etc and the second being the device name when available or None.

On my machine I have:

/dev/serial/by-id/usb-SEGGER_J-Link_emulator_001050286728-if00 -> ../../ttyACM1
...

I would expect something like Ok(["/dev/ttyACM1", Some("usb-SEGGER_J-Link_emulator_001050286728-if00"), ...]) as the result of that function call.

EDIT: Or maybe without the "usb-" prefix. It would be really nice if the device names could be the same on multiple platforms. I've got a program (otii-measurement) that talks to a Otii Arc energy analyzer. Currently I've got its usual linux device name (/dev/serial/by-id/usb-Qoitech_Arc-if00) as the default device parameter in my program, but it would be nice if I could find the right device on all platforms given the device name instead. There I suspect the "usb-" prefix is only available on linux.

[de-vri-es]

I like the idea of providing a path and additional information separately.

Maybe we should immediately use a SerialPortInfo struct for the information, so we can add more information in the future without breaking the API.