How can Windows service running as System account get current user's \AppData\Local\ special-folder?

Question

My app is a windows desktop exe, and windows service which runs under the System account. My windows service needs to integrate with a 3rd party app that the user will also install which stores some config info in an ini file within one of the windows special-folders at: C:\Users\[UserName]\AppData\Local\[3rd party app name]

How can my Windows Service retrieve the current user's path to that folder to read the ini file in it, when the windows service runs as System account?

Ideally, I would have used something like

Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)

which returns the correct \AppData\Local\ folder when run from an app running as the current user.

But because my windows service is running as SYSTEM (which cannot be changed) that method instead returns: C:\Windows\system32\config\systemprofile\AppData\Local

So how can my windows service get the currently logged in user's LocalApplicationData special folder?

Answer 1

The code below shows how to get a list of logged in users. Once you have a list of logged in users, then you can check the last updated time of the file (File.GetLastWriteTime) that you're interested in.

Add Reference: System.Management

Create a class (name: UserInfo.cs)

UserInfo.cs:

public class UserInfo : IComparable<UserInfo>
{
    public string Caption { get; set; }
    public string DesktopName { get; set; }
    public string Domain { get; set; }
    public bool IsLocalAccount { get; set; } = false;
    public bool IsLoggedIn { get; set; } = false;
    public bool IsRoamingConfigured { get; set; } = false;
    public DateTime LastUploadTime { get; set; }
    public DateTime LastUseTime { get; set; }
    public string LocalPath { get; set; }
    public bool IsProfileLoaded { get; set; } = false;
    public string ProfilePath { get; set; }
    public string SID { get; set; }
    public uint SIDType { get; set; }
    public string Status { get; set; }
    public string Username { get; set; }

    public int CompareTo(UserInfo other)
    {
        //sort by name
        if (this.Caption == other.Caption)
            return 0;
        else if (String.Compare(this.Caption, other.Caption) > 1)
            return 1;
        else
            return -1;
    }

    public override string ToString()
    {
        string output = string.Empty;
        output += $"Caption: '{Caption}'{Environment.NewLine}";
        output += $"Domain: '{Domain}'{Environment.NewLine}";
        output += $"Username: '{Username}'{Environment.NewLine}";
        output += $"IsProfileLoaded: '{IsProfileLoaded}'{Environment.NewLine}";
        output += $"IsRoamingConfigured: '{IsRoamingConfigured}'{Environment.NewLine}";
        output += $"LocalPath: '{LocalPath}'{Environment.NewLine}";
        output += $"LastUseTime: '{LastUseTime.ToString("yyyy/MM/dd HH:mm:ss")}'{Environment.NewLine}";
        output += $"SID: '{SID}'{Environment.NewLine}";

        return output;
    }
}

GetLoggedInUserInfo:

public List<UserInfo> GetLoggedInUserInfo()
{
    List<UserInfo> users = new List<UserInfo>();

    //create reference
    System.Globalization.CultureInfo cultureInfo = System.Globalization.CultureInfo.CurrentCulture;

    using (ManagementObjectSearcher searcherUserAccount = new ManagementObjectSearcher("SELECT Caption, Domain, LocalAccount, Name, SID, SIDType, Status FROM Win32_UserAccount WHERE Disabled = false"))
    {
        foreach (ManagementObject objUserAccount in searcherUserAccount.Get())
        {
            if (objUserAccount == null)
                continue;

            //create new instance
            UserInfo userInfo = new UserInfo();

            string caption = objUserAccount["Caption"].ToString();

            //set value
            userInfo.Caption = caption;
            userInfo.Domain = objUserAccount["Domain"].ToString();

            userInfo.IsLocalAccount = (bool)objUserAccount["LocalAccount"];
            userInfo.Username = objUserAccount["Name"].ToString();

            string sid = objUserAccount["SID"].ToString();

            userInfo.SID = sid;
            userInfo.SIDType =  Convert.ToUInt32(objUserAccount["SIDType"]);
            userInfo.Status = objUserAccount["Status"].ToString();

            using (ManagementObjectSearcher searcherUserProfile = new ManagementObjectSearcher($"SELECT LastUseTime, LastUploadTime, Loaded, LocalPath, RoamingConfigured FROM Win32_UserProfile WHERE SID = '{sid}'"))
            {
                foreach (ManagementObject objUserProfile in searcherUserProfile.Get())
                {
                    if (objUserProfile == null)
                        continue;

                    if (objUserProfile["LastUploadTime"] != null)
                    {
                        string lastUploadTimeStr = objUserProfile["LastUploadTime"].ToString();

                        if (lastUploadTimeStr.Contains("."))
                            lastUploadTimeStr = lastUploadTimeStr.Substring(0, lastUploadTimeStr.IndexOf("."));

                        DateTime lastUploadTime = DateTime.MinValue;

                        //convert DateTime
                        if (DateTime.TryParseExact(lastUploadTimeStr, "yyyyMMddHHmmss", cultureInfo, System.Globalization.DateTimeStyles.AssumeUniversal, out lastUploadTime))
                            userInfo.LastUseTime = lastUploadTime;

                        //set value
                        userInfo.LastUploadTime = lastUploadTime;
                    }


                    string lastUseTimeStr = objUserProfile["LastUseTime"].ToString();

                    if (lastUseTimeStr.Contains("."))
                        lastUseTimeStr = lastUseTimeStr.Substring(0, lastUseTimeStr.IndexOf("."));

                    DateTime lastUseTime = DateTime.MinValue;

                    //convert DateTime
                    if (DateTime.TryParseExact(lastUseTimeStr, "yyyyMMddHHmmss", cultureInfo, System.Globalization.DateTimeStyles.AssumeUniversal, out lastUseTime))
                        userInfo.LastUseTime = lastUseTime;

                    //Debug.WriteLine($"LastUseTime: '{objUserProfile["LastUseTime"].ToString()}' After Conversion: '{lastUseTime.ToString("yyyy/MM/dd HH:mm:ss")}'");

                    userInfo.LocalPath = objUserProfile["LocalPath"].ToString();
                    userInfo.IsProfileLoaded = (bool)objUserProfile["Loaded"];
                    userInfo.IsRoamingConfigured = (bool)objUserProfile["RoamingConfigured"];
                }
            }

            if (userInfo.IsProfileLoaded)
            {
                Debug.WriteLine(userInfo.ToString());

                //add
                users.Add(userInfo);
            }
        }
    }

    //sort by LastUseTime
    users.Sort(delegate (UserInfo info1, UserInfo info2) { return info1.LastUseTime.CompareTo(info2.LastUseTime); });

    return users;
}

Usage:

List<UserInfo> users = GetLoggedInUserInfo();

Resources:

• Win32_UserAccount Class
• Win32_UserProfile Class
• ManagementObjectSearcher Class
• ManagementObject Class
• File.GetLastWriteTime Method