Tiny refactor for USB device IDs

Unfortunately, it's impossible to print device manufacturer and product strings during attach/detach: device needs to be opened, and that doesn't work even in attach.

src/platform/pnp_detect_libusb.rs

@@ -3,32 +3,31 @@
 // This code is licensed under MIT license (see LICENSE.txt for details)
 //
 
-use crate::usb::{device2str, UsbCallback};
 use anyhow::{anyhow, Result};
 use rusb::{Context, Device, HotplugBuilder, Registration, UsbContext};
 
 /// Detection of plugged in / removed USB devices: uses "libusb" and should work on Linux
 /// and MacOS, but not on Windows: libusb does not support hotplug on Windows.
 pub struct PnPDetectLibusb {
-    callback: Box<dyn UsbCallback + Send>,
+    callback: Box<dyn crate::usb::UsbCallback + Send>,
 }
 
 impl<T: UsbContext> rusb::Hotplug<T> for PnPDetectLibusb {
     fn device_arrived(&mut self, device: Device<T>) {
-        if let Some(str) = device2str(device) {
+        if let Some(str) = crate::usb::device_id(&device) {
             self.callback.device_added(&str)
         }
     }
 
     fn device_left(&mut self, device: Device<T>) {
-        if let Some(str) = device2str(device) {
+        if let Some(str) = crate::usb::device_id(&device) {
             self.callback.device_removed(&str)
         }
     }
 }
 
 impl PnPDetectLibusb {
-    pub fn new(callback: Box<dyn UsbCallback + Send>) -> Box<Self> {
+    pub fn new(callback: Box<dyn crate::usb::UsbCallback + Send>) -> Box<Self> {
         Box::new(PnPDetectLibusb { callback })
     }
 

src/platform/pnp_detect_windows.rs

@@ -8,7 +8,6 @@ use std::ffi::OsStr;
 use std::iter::once;
 use std::os::windows::ffi::OsStrExt;
 
-use crate::usb::{device2str, UsbCallback};
 use anyhow::{anyhow, Result};
 use winapi::shared::minwindef::{LPARAM, LRESULT, UINT, WPARAM};
 use winapi::shared::ntdef::LPCWSTR;
@@ -24,12 +23,12 @@ use winapi::um::winuser::{
 /// https://github.com/libusb/libusb/issues/86
 pub struct PnPDetectWindows {
     hwnd: HWND,
-    callback: Box<dyn UsbCallback>,
+    callback: Box<dyn crate::usb::UsbCallback>,
     current_devices: HashSet<String>,
 }
 
 impl PnPDetectWindows {
-    pub fn new(callback: Box<dyn UsbCallback>) -> Box<Self> {
+    pub fn new(callback: Box<dyn crate::usb::UsbCallback>) -> Box<Self> {
         let mut pnp_detect = Box::new(Self {
             callback,
             current_devices: Self::read_device_list().unwrap_or_default(),
@@ -62,7 +61,7 @@ impl PnPDetectWindows {
     fn read_device_list() -> Result<HashSet<String>> {
         Ok(rusb::devices()?
             .iter()
-            .map(|device| device2str(device).ok_or(anyhow!("Cannot get device Ids")))
+            .map(|device| crate::usb::device_id(&device).ok_or(anyhow!("Cannot get device Ids")))
             .collect::<std::result::Result<_, _>>()?)
     }
 

src/usb.rs

@@ -4,13 +4,25 @@
 //
 use rusb::UsbContext;
 
-pub fn device2str<T: UsbContext>(device: rusb::Device<T>) -> Option<String> {
+pub fn device_id<T: UsbContext>(device: &rusb::Device<T>) -> Option<String> {
     device
         .device_descriptor()
         .map(|device_desc| format!("{:04x}:{:04x}", device_desc.vendor_id(), device_desc.product_id()))
         .ok()
 }
 
+// pub fn device_product_name<T: UsbContext>(device: &rusb::Device<T>) -> Option<String> {
+//     let descriptor = device.device_descriptor().ok()?;
+//     let handle = device.open().ok()?;
+//     handle.read_product_string_ascii(&descriptor).ok()
+// }
+//
+// pub fn device_manufacturer_name<T: UsbContext>(device: &rusb::Device<T>) -> Option<String> {
+//     let descriptor = device.device_descriptor().ok()?;
+//     let handle = device.open().ok()?;
+//     handle.read_manufacturer_string_ascii(&descriptor).ok()
+// }
+
 pub trait UsbCallback: Send {
     fn device_added(&self, device_id: &str);
     fn device_removed(&self, device_id: &str);