MapPath or equivalent to use in an installation application

I need to check a .config file in an installation application (iis custom action in a WIX project). The user picks a website and enters a virtual directory name. I can't do a http read to retrieve the config f开发者_高级运维ile as ASP.NET does not serve config files.

How can I find the local disk path of the selected website and virtual directory?

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After further searching, I ended up using DirectoryServices. I'm posting my solution here for others.

If there is a better way, please still post it.

    static string FindVirtualDirectoryPath(string virtualDirectoryName)
    {
        return FindVirtualDirectoryPath(null, virtualDirectoryName);
    }

    static string FindVirtualDirectoryPath(string siteName, string virtualDirectoryName)
    {
        DirectoryEntry iis = new DirectoryEntry("IIS://localhost/W3SVC");
        foreach (DirectoryEntry index in iis.Children)
        {
            if (index.SchemaClassName == "IIsWebServer")
            {
                int id = Convert.ToInt32(index.Name);
                DirectoryEntry site = new DirectoryEntry(string.Concat("IIS://localhost/W3SVC/", id));
                string iSiteName = site.Properties["ServerComment"].Value.ToString();
                if (iSiteName == siteName || (string.IsNullOrEmpty(siteName) && id == 1))
                {
                    DirectoryEntry rootVDir = new DirectoryEntry(string.Concat("IIS://localhost/W3SVC/", id, "/Root"));
                    foreach (DirectoryEntry vDir in rootVDir.Children)
                    {
                        if (vDir.SchemaClassName == "IIsWebVirtualDir" && vDir.Name.ToLower() == virtualDirectoryName.ToLower())
                        {
                            return vDir.Properties["Path"].Value.ToString();
                        }
                    }
                }
            }
        }
        return null;
    }

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Have you tried using the standard WiX IIsExtension for this? Just capture the user input in a property, and then use standard elements like iis:WebSite and iis:WebVirtualDir to create a virtual directory in appropriate web site.