Identifying a text file as UNIX or DOS format

Hello,
I would be very grateful for some help from the VBA I/O-experienced on this forum.

I'm writing an application to do some conversion on log file timestamps. I have it mostly completed, but am stuck on one issue: These files are text files which could have come from Windows/DOS or UNIX.
I am reading them using sequential access (Open filename for Input as #n, etc)

If they are Windows, it is pretty straightforward:

• text file lines are terminated by CR/LF (or vbCrlf) and Excel reads them fine, splitting up neatly into records

If they are from UNIX, then I have a problem.

• The records are terminated just with an LF which VBA does not recognize as a terminator, So it reads the whole file in as one humongous record.

Now this is okay. In the UNIX streams I can replace the LFs with CR/LFs and write out the file using binary I/O. It works.

Heres my problem: I don't know in advance whether a file is going to be UNIX or DOS format. And what I'm looking for is the most neat/effective way to determine this.
I can do something like count the records, and if there are more than one, conclude that it is a DOS file. But that seems clumsy, and these files are pretty big. The first one I tested was UNIX and gave me one string of length 800,000+ .

Any suggestiobns/solutions?
Cheers and many thanks in advance


For completeness, here's my code for the UnIX to DOS conversion:

Public Function CnvFil(InputFile As String, OutputFile As String)    

    Dim Ifn as integer, Ofn as Integer
    Dim Buffer As String
    
    Ifn = FreeFile
    Open InputFile For Input As #Ifn 
    Ofn = FreeFile 
    Open OutputFile For Binary As #Ofn
    Do While Not EOF(Ifn)
                Line Input #Ifn, Buffer  'if UNIX then there will be only one line
                Buffer = Replace(Buffer, vbLf, vbCrLf)
                Put #Ofn , Buffer  ' write file
     Loop
     Close #Ofn
     Close #Ifn
     
 End Function