Add location field to UsbPortInfo

It returns stable full path to the serial port. Returned value is formatted as `a-b.c` where `a` is a bus_id and `b` and `c` are port numbers.

src/lib.rs

@@ -787,6 +787,8 @@ pub struct UsbPortInfo {
     pub manufacturer: Option<String>,
     /// Product name (arbitrary string)
     pub product: Option<String>,
+    /// Location (bus_id-a.b string)
+    pub location: String,
     /// The interface index of the USB serial port. This can be either the interface number of
     /// the communication interface (as is the case on Windows and Linux) or the data
     /// interface (as is the case on macOS), so you should recognize both interface numbers.

src/posix/enumerate.rs

@@ -344,6 +344,24 @@ fn get_string_property(device_type: io_registry_entry_t, property: &str) -> Resu
         .ok_or(Error::new(ErrorKind::Unknown, "Failed to get string value"))
 }
 
+/// Parse location_id by extracting bits that represent specific parts of
+/// the USB device’s location within the USB topology, such as the bus and
+/// port numbers, and then formats them in a hierarchical form like “0-1.2.4”.
+fn location_to_string(location_id: u32) -> String {
+    let mut location_id = location_id;
+    let bus_id =  format!("{:02x}", (location_id >> 24) as u8);
+    let mut path = format!("{bus_id}-");
+    while location_id & 0xf00000 != 0 {
+        let item = (location_id >> 20) & 0xf;
+        if !path.ends_with("-") {
+            path.push_str(".");
+        }
+        path.push_str(item.to_string().as_str());
+        location_id <<= 4;
+    }
+    return path;
+}
+
 #[cfg(any(target_os = "ios", target_os = "macos"))]
 /// Determine the serial port type based on the service object (like that returned by
 /// `IOIteratorNext`). Specific properties are extracted for USB devices.
@@ -355,12 +373,14 @@ fn port_type(service: io_object_t) -> SerialPortType {
     let maybe_usb_device = get_parent_device_by_type(service, usb_device_class_name)
         .or_else(|| get_parent_device_by_type(service, legacy_usb_device_class_name));
     if let Some(usb_device) = maybe_usb_device {
+        let location_id = get_int_property(usb_device, "locationID").unwrap_or_default() as u32;
         SerialPortType::UsbPort(UsbPortInfo {
             vid: get_int_property(usb_device, "idVendor").unwrap_or_default() as u16,
             pid: get_int_property(usb_device, "idProduct").unwrap_or_default() as u16,
             serial_number: get_string_property(usb_device, "USB Serial Number").ok(),
             manufacturer: get_string_property(usb_device, "USB Vendor Name").ok(),
             product: get_string_property(usb_device, "USB Product Name").ok(),
+            location: location_to_string(location_id),
             // Apple developer documentation indicates `bInterfaceNumber` is the supported key for
             // looking up the composite usb interface id. `idVendor` and `idProduct` are included in the same tables, so
             // we will lookup the interface number using the same method. See: