Question

I have a dll when its software gets installed, it gets installed in

HKEY_LOCAL_MACHINE\\SOFTWARE for 32-bit OS and

HKEY_CURRENT_USER\\SOFTWARE for 64-bit OS.

How do i detect the dll path based on the registry key ?

I don’t want to hard code like this.

RegistryKey registryKey = Registry.LocalMachine.OpenSubKey("Software//NodeName")

I can try detecting 32-bit or 64-bit OS and do something like

If 32-bit

RegistryKey registryKey = Registry.LocalMachine.OpenSubKey("Software//NodeName")

If 64-bit

RegistryKey registryKey = Registry.CurrentUser.OpenSubKey("Software//NodeName")

But is there a way i can detect the path of the dll directly if for example the dll name is specified and how do i do an entire registry check and find its path name?

Answer 1

HKEY_CLASSES_ROOT\CLSID contains the list of all registered COM files (.ocx,.dll, .ax) on the system no matters if is 32 or 64 bits.

The key under CLSID is represented by the generated GUID of each COM.

And finaly into the GUID key, there is the InprocServer32 sub-key, in it, the default value contains the path of the COM file into the sistem so you can find it as follows:

VB CODE:

    ''' <summary>
    ''' Search and Find Registry Function
    ''' </summary>
    Public Shared Function SearchRegistry(ByVal dllName As String) As String

        'Open the HKEY_CLASSES_ROOT\CLSID which contains the list of all registered COM files (.ocx,.dll, .ax) 
        'on the system no matters if is 32 or 64 bits.
        Dim t_clsidKey As RegistryKey = Registry.ClassesRoot.OpenSubKey("CLSID")

        'Get all the sub keys it contains, wich are the generated GUID of each COM.
        For Each subKey In t_clsidKey.GetSubKeyNames.ToList

            'For each CLSID\GUID key we get the InProcServer32 sub-key .
            Dim t_clsidSubKey As RegistryKey = Registry.ClassesRoot.OpenSubKey("CLSID\" & subKey & "\InProcServer32")

            If Not t_clsidSubKey Is Nothing Then

                'in the case InProcServer32 exist we get the default value wich contains the path of the COM file.
                Dim t_valueName As String = (From value In t_clsidSubKey.GetValueNames() Where value = "")(0).ToString

                'Now gets the value.
                Dim t_value As String = t_clsidSubKey.GetValue(t_valueName).ToString


                'And finaly if the value ends with the name of the dll (include .dll) we return it
                If t_value.EndsWith(dllName) Then

                    Return t_value

                End If

            End If

        Next

        'if not exist, return nothing
        Return Nothing

    End Function

C# CODE:

    /// <summary>
    /// Search and Find Registry Function
    /// </summary>
    public static string SearchRegistry(string dllName)
    {

        //Open the HKEY_CLASSES_ROOT\CLSID which contains the list of all registered COM files (.ocx,.dll, .ax) 
        //on the system no matters if is 32 or 64 bits.
        RegistryKey t_clsidKey = Registry.ClassesRoot.OpenSubKey("CLSID");

        //Get all the sub keys it contains, wich are the generated GUID of each COM.

        foreach (object subKey_loopVariable in t_clsidKey.GetSubKeyNames.ToList) {
            subKey = subKey_loopVariable;
            //For each CLSID\GUID key we get the InProcServer32 sub-key .
            RegistryKey t_clsidSubKey = Registry.ClassesRoot.OpenSubKey("CLSID\\" + subKey + "\\InProcServer32");


            if ((t_clsidSubKey != null)) {
                //in the case InProcServer32 exist we get the default value wich contains the path of the COM file.
                string t_valueName = (from value in t_clsidSubKey.GetValueNames()where string.IsNullOrEmpty(value))(0).ToString;

                //Now gets the value.
                string t_value = t_clsidSubKey.GetValue(t_valueName).ToString;


                //And finaly if the value ends with the name of the dll (include .dll) we return it

                if (t_value.EndsWith(dllName)) {
                    return t_value;

                }

            }

        }

        //if not exist, return nothing
        return null;

    }