Unable to retrieve Android device manufacturer and product strings

[Tryanks]

On a Linux machine, I installed libusb-1.0-0-dev and started implementing the AOAv2 protocol, which I plan to use for registering a HID device on Android. However, I have not even reached the AOAv2-specific part yet. At the very first step, simply reading the USB string descriptors already fails.

Minimal reproducer

package main

import (
	"fmt"
	"log"

	libusb "github.com/gotmc/libusb/v2"
)

func main() {
	ctx, err := libusb.NewContext()
	if err != nil {
		log.Fatalf("new context failed: %v", err)
	}
	defer ctx.Close()

	dev, handle, err := ctx.OpenDeviceWithVendorProduct(0x2717, 0xff48)
	if err != nil {
		log.Fatalf("open device failed: %v", err)
	}
	defer dev.Close()
	defer handle.Close()

	desc, err := dev.DeviceDescriptor()
	if err != nil {
		log.Fatalf("read device descriptor failed: %v", err)
	}

	fmt.Printf("VID:PID = %04x:%04x\n", desc.VendorID, desc.ProductID)
	fmt.Printf("ManufacturerIndex = %d\n", desc.ManufacturerIndex)
	fmt.Printf("ProductIndex      = %d\n", desc.ProductIndex)

	manufacturer, err := handle.StringDescriptorASCII(desc.ManufacturerIndex)
	if err != nil {
		log.Fatalf("read manufacturer failed: %v", err)
	}

	product, err := handle.StringDescriptorASCII(desc.ProductIndex)
	if err != nil {
		log.Fatalf("read product failed: %v", err)
	}

	fmt.Printf("Manufacturer = %q\n", manufacturer)
	fmt.Printf("Product      = %q\n", product)
}

On my actual device, I would expect the manufacturer and product strings to be:

• "Xiaomi"
• "MI 8"

Instead, I get empty strings together with resource temporarily unavailable.

More specifically:

• StringDescriptorASCII() returns "" with resource temporarily unavailable
• StringDescriptor() returns malformed / truncated data such as "\x0e\x03X"

From reading the behavior and comparing the results, I suspect there may be implementation issues in these two methods:

• StringDescriptorASCII() seems to have incorrect error handling
• StringDescriptor() appears to treat the USB string descriptor as a C string, which may explain the truncation / malformed output