Check if file is open, including subfolders in VBA

Question

I need to check if a file is already open in order to speed up my code. Currently, it loops through a list, opens a file with a path and the file name comes from the list, there's a few lines of code that means if the file I want to open is in a folder within this path, it can still do that:

If Not IsFileOpen("G:\BS\Josh Whitfield\1. Work work\Credit_Chasing\NEW PROCESS\" & file) Then
    If filevar <> "" Then
        Workbooks.Open "G:\BS\Josh Whitfield\1. Work work\Credit_Chasing\NEW PROCESS\" & file
    Else
        Workbooks.Open "G:\BS\Josh Whitfield\1. Work work\Credit_Chasing\NEW PROCESS\" & Range("F" & i).Value & "\" & file
    End If
End If

I also have a function that will detect if the file is already open, but I would like a better one or some help getting this current one to work with subfolders:

Function IsFileOpen(filename As String)
    Dim filenum As Integer, errnum As Integer

    On Error Resume Next   ' Turn error checking off.
    filenum = FreeFile()   ' Get a free file number.
    ' Attempt to open the file and lock it.
    Open filename For Input Lock Read As #filenum
    Close filenum          ' Close the file.
    errnum = Err           ' Save the error number that occurred.
    On Error GoTo 0        ' Turn error checking back on.

    ' Check to see which error occurred.
    Select Case errnum

        ' No error occurred.
        ' File is NOT already open by another user.
        Case 0
         IsFileOpen = False

        ' Error number for "Permission Denied."
        ' File is already opened by another user.
        Case 70
            IsFileOpen = True

        ' Another error occurred.
        Case Else
            Error errnum
    End Select

End Function

Thanks for any help!

Answer 1

Managed to solve it with a different function:

Function IsWorkBookOpen(FileName As String)
    Dim ff As Long, ErrNo As Long
    subCheck = False
    On Error Resume Next
    ff = FreeFile()
    Open FileName For Input Lock Read As #ff
    Close ff
    ErrNo = Err
    On Error GoTo 0

    IsWorkBookOpen = ""

    Select Case ErrNo
    Case 0:    IsWorkBookOpen = False
    Case 70:   IsWorkBookOpen = True
    Case Else: IsWorkBookOpen = ""
    End Select
End Function

and the setup for the sub:

ret = IsWorkBookOpen("G:\BS\Josh Whitfield\1. Work work\Credit_Chasing\NEW PROCESS\" & file)
        retSub = subCheck

    If ret <> True Then
        If ret = False Then
            Workbooks.Open "G:\BS\Josh Whitfield\1. Work work\Credit_Chasing\NEW PROCESS\" & file
        ElseIf ret = "" Then
            'subCheck = True
            Workbooks.Open "G:\BS\Josh Whitfield\1. Work work\Credit_Chasing\NEW PROCESS\" & Range("F" & i).Value & "\" & file
        End If
    End If

THIS CODE WONT WORK FOR EVERYONE IF YOU WANT TO CHECK IF THE FILE IS OPEN, it works for my purposes because I don't mind 3 types of files being open, this is not an entirely reliable method.