gotmc / usbtmc Goto Github PK

Add a USBTMC driver (usbtmc/driver/libusb) for the github.com/gotmc/libusb Go-based libusb driver.

It appears the Agilent/Keysight U2751A 4x8 2-wire switch matrix uses usbtmc-usb488 subclass.

regString := ^(?P<interfaceType>[A-Za-z]+)(?P<boardIndex>\d*):: +
(?P<manufacturerID>[^\s:]+):: +
(?P<modelCode>[^\s:]+) +
(::(?P<serialNumber>[^\s:]+))? +
::(?P<resourceClass>[^\s:]+)$

there is some error in this regString, when parse the string USB0::0x0957::0x2007::MY57004760::0::INSTR

A MWE:

package main

import (
	"log"

	"github.com/gotmc/usbtmc"
	_ "github.com/gotmc/usbtmc/driver/truveris"
)

func main() {
	ctx, err := usbtmc.NewContext()
	if err != nil {
		log.Fatal(err)
	}
	ctx.SetDebugLevel(1)
}

Output:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x49c9c0]

goroutine 1 [running]:
<>/vendor/github.com/gotmc/usbtmc.NewContext(0x4c92e0, 0x78a790, 0x0)
	/media/psf/Home/go/src/<>/vendor/github.com/gotmc/usbtmc/context.go:20 +0x70
main.main()
	/media/psf/Home/go/src/<>/cmd/ldctest/main.go:19 +0x26

This is without any of the other drivers installed. If I uninstall this driver and install another, I get the same segfault with the other two.

Add USBTMC driver (usbtmc/driver/gousb) for the github.com/google/gousb Go-based libusb driver.

Instead of calling log.Fatal(), return an error, so that the end-user's higher level application can decide how to handle.

I don't want users to have to constantly append "\n" to their queries or string writers.

In device.go the Read(p []byte) method uses a fixed length of 1024 to read the USBTMC bulk-in endpoint. Seems like I should refactor this.