C# – How to get the drive letter of USB device using WMI

cwmi

I need to track the USB insertion and removal events from the C# application so I came up with the following ideas based on the other questions on SO.

I can't use this method

var drives = DriveInfo.GetDrives()
    .Where(drive => drive.IsReady && drive.DriveType == DriveType.Removable).ToList();

because it can lead to a lot of troubles when you need to differentiate between connected and disconnected devices (the new ones can have the same drive letter and name like the ones that was previously cached).

So I decided to use WMI to solve this problem but I found that it's impossible to get the drive letter of the specified USB device via Win32_USBHub class. Then I thought that I can execute another query like this

foreach (ManagementObject device in new ManagementObjectSearcher(@"SELECT * FROM Win32_USBHub").Get())
{
    string deviceID = (string)device.GetPropertyValue("DeviceID");

    Console.WriteLine("{0}", deviceID);

    string query = string.Format("SELECT * FROM Win32_LogicalDisk WHERE DeviceID='{0}'", deviceID);
    foreach (ManagementObject o in new ManagementObjectSearcher(query).Get())
    {
        string name = (string)o.GetPropertyValue("Name");
        Console.WriteLine("{0}", name);
    }

    Console.WriteLine("==================================");
}

but it doesn't work at all — I get an exception "Invalid query" every time when I try to execute query that works with the Win32_LogicalDisk table.

Why? What am I doing wrong? How can I fix it? Maybe there is a better ways to solve this problem?

Thanks in advance.

Best Answer

You get an exception because your deviceID contains characters that need to be escaped (backslashes). With simple replace you shouldn't get the exception.

string query = string.Format("SELECT * FROM Win32_LogicalDisk WHERE DeviceID='{0}'", deviceID.Replace(@"\", @"\\"));

However, getting USB drive letter from WMI is a little more complicated. You need to go through a few classes, as stated in a link that @MSalters posted in his comment:

Win32_DiskDrive-> Win32_DiskDriveToDiskPartition -> Win32_DiskPartition -> Win32_LogicalDiskToPartition -> Win32_LogicalDisk.

A little modified version of code found here worked for me:

foreach (ManagementObject device in new ManagementObjectSearcher(@"SELECT * FROM Win32_DiskDrive WHERE InterfaceType LIKE 'USB%'").Get())
{
    Console.WriteLine((string)device.GetPropertyValue("DeviceID"));
    Console.WriteLine((string)device.GetPropertyValue("PNPDeviceID"));                

    foreach (ManagementObject partition in new ManagementObjectSearcher(
        "ASSOCIATORS OF {Win32_DiskDrive.DeviceID='" + device.Properties["DeviceID"].Value
        + "'} WHERE AssocClass = Win32_DiskDriveToDiskPartition").Get())
    {
        foreach (ManagementObject disk in new ManagementObjectSearcher(
                    "ASSOCIATORS OF {Win32_DiskPartition.DeviceID='"
                        + partition["DeviceID"]
                        + "'} WHERE AssocClass = Win32_LogicalDiskToPartition").Get())
        {
            Console.WriteLine("Drive letter " + disk["Name"]);
        }
    }
}

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This changes if you put the using inside your namespace declaration, as follows:

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Best Answer

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