string represents a shortcut link? (VB/VBA any)

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Is there a better way to test if a string represents a shortcut link?

Sub TESTblnShortCut()
    MsgBox blnShortCut("C:Blotter200604041")
    MsgBox blnShortCut("C:Blotter200604041", ".lnk")
    MsgBox blnShortCut("C:Blotter200604041", ".bat")
End Sub

Public Function blnShortCut(ByVal strfile As String, Optional strExtent) As Boolean
    On Error GoTo Failed
    If FileLen(strfile) > 0 Then
    Else
    End If
    Exit Function
Failed:
    Dim strExt As String
    If IsMissing(strExtent) Then
        strExt = ".lnk"
    Else
        strExt = strExtent
    End If
    strfile = strfile & strExt
    blnShortCut = blnShortCut2(strfile)
End Function
Public Function blnShortCut2(ByVal strfile As String) As Boolean
    On Error GoTo Failed
    If FileLen(strfile) > 0 Then
    Else
    End If
    blnShortCut2 = True
    Exit Function
Failed:
End Function

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What are you doing? I can’t follow it.

What is FileLen?

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>What are you doing? I can’t follow it.
Basically, if a file is a shortcut link, the extent “lnk” does not appear when I FSO or similar to retrieve file names.
If I test for the existence (FileLen) of the filename as given (without the extent) it fails, so generates an error.
If I append a best-guess at an extent and test again and this time the FileLen does NOT generate an error, it’s probably a shortcut; that is, appending the “lnk” extent indicated that there is such a file, so the original file name without the “lnk” was a shortcut link.

FileLen returns the length of the file in bytes, as in

Sub test()
    MsgBox FileLen(MacroContainer.FullName)
End Sub

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If you feed your function “1.lnk”, it returns False, which isn’t what you want, correct?

Does the following do what you want?

Function blnShortCut(strFile As String) As Boolean

    If Right$(strFile, 4) = ".lnk" Then
        If FileLen(strFile) > 0 Then
            blnShortCut = True
        End If
     Else
        If FileLen(strFile & ".lnk") > 0 Then
            blnShortCut = True
        End If
    End If

End Function

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Thanks for your patience.

> If you feed your function “1.lnk”, it returns False, which isn’t what you want, correct?
You are correct. However If I am given a filename with an extension of “lnk”, I’m prepared to accept it as a shortcut link. (Further analysis will reveal whether or not it really is a link).
My problem is determining if a file other than one with an explicit extension of “lnk” is a shortcut link.
Try running this code on a folder that contains a mixture of shortcuts and regular files

Public Sub GetFolderItems()
' needs a reference to microsoft shells and controls automation
    On Error Resume Next
    Dim FI As Shell32.FolderItem, i As Long
    With New Shell
        With .NameSpace("c:Blotter20060404")
            For Each FI In .Items
                If Not (FI Is Nothing) Then
                    If FI.IsFolder Then
                        'evaluate this namespece
                    Else
                        'add to dictionary
                        Debug.Print FI.Name
                    End If
                End If
            Next
        End With
    End With
    Set FI = Nothing
End Sub

On my Office 2000 system it returns the shortcut link files without the “lnk” extension. Us mortals aren’t told about the extension on shortcut link files.
I was/am looking for a way to determine if a file passed to me by the system routines is a link file, or is just a regular file.
I may have missed something in reading the help files and various forums and newsgroups, but it seems to me that we are not given that “lnk” extension, and must play a bit of a guessing game to see if the file really is a shortcut. (“Does it have an extension, if so, is it “lnk”, if not, if i place a “lnk” there does the file exist? …)

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Your latest post is consistent with my assumptions about what you were doing, so I think the code in my previous post will do what you want, but I may be missing something. (You could shorten it a little if you’ve already determined the target file doesn’t end in .lnk before you invoke the blnShortCut function.)

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On my system (Office 2K, running on WIN XP) the FileSystemObject methods correctly listed files with the .lnk extension. Not sure why your system did not reflect this. Anyway if interested see attached text file, exported VBA code module. The ListFiles sub lists all files in specified folder (using FSO) & related info. If file has “.lnk” extension the FSO File.Type property returns “Shortcut” (based solely on file extension as registered in Windows Registry). However you can rename a file with .lnk extension whether or not a valid shortcut (you can tell if valid or not by right-clicking file & opening “Properties” dialog – the Target Type will read, “This is not a valid shortcut.”) You could use ShellExecute function to open Properties dialog programatically, but that wouldn’t be too useful… Tried using WSH methods to verify if valid shortcut, but that did not work either – there is no “OpenShortcut” method, only the CreateShortcut method (which can be used to open existing shortcut). This proved not very useful, since you can create a new shortcut w/o target path, etc, specified – see IsShortcutWSH function as an exercise in futility. Finally decided most reliable method is that used in IsShortcut function – if valid file spec with .lnk extension, read the first 20 bytes of file into a Byte array. A valid shortcut file will always have the letter “L” (or Hex 4C) (4 bytes) followed by a 16-byte GUID in the first 20 bytes of file header (you can test this by running ListFiles with a folder that has valid shortcut files – you should see the same 20 byte values listed). The bogus “.lnk” file will return False when run function. If running repeatedly you’d probably want to populate the bTest byte array only once. See attached text file for details. This worked correctly on two different Office 2K/WIN XP systems. You may be able to adapt this for your purposes.

HTH

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Mark, thanks for the extensive and exhaustive research.

>there is no “OpenShortcut” method, only the CreateShortcut method
I have recollections of seeing something, somewhere, along the lines of “there is no “OpenShortcut” method, only the CreateShortcut method … but the Create method can be used to create an object that can be tested.”. I must go back over my notes and di that out. (later) i think this is it

    For lng = LBound(strFiles) To UBound(strFiles)
        Dim strTarget As String
        strTarget = Utils.strShortCut(strFiles(lng))
        If Len(strTarget) > 0 Then ' it is a shortcut link
            Dim strMsg As String
            strMsg = "Shortcut file " & strFiles(lng)
            Application.StatusBar = Trim(Str(lng)) & "/" & Trim(Str(UBound(strFiles))) & " " & strFiles(lng)
            With CreateObject("WScript.Shell").CreateShortcut(strTarget)
                Dim strTargetPath As String
                strTargetPath = .targetpath
                If UW.blnfileexists(strTargetPath) Then
                    strMsg = strMsg & " found "
                Else
                    strMsg = strMsg & " NOT found "
                    Call UW.KillFile(strTarget)
                End If
                Call logfile((strEnv) & strcApplication & ".LOG", strMsg)
            End With
        Else
        End If
    Next lng

The “With CreateObject(“WScript.Shell”).CreateShortcut(strTarget)” creates an object but doesn’t .Save it (yet), and the object, which just so happens to refer to an existing file, can then be interrogated.
I’m not sure of this, but it seems to work.

>A valid shortcut file will always have the letter “L” (or Hex 4C) (4 bytes) followed by a 16-byte GUID in the first 20 bytes of file header
This is of very high value for two reasons:
(1) I can add it to my set of constraints for testing file types by content, such as WP5.1 DOS files etc
(2) The current application is an Archiver, so grabbing 20 bytes of an existing file is no big deal, given that we are a background, low-priority task anyway, and it is wise to take every step possible to identify correctly each file.

Again, Mark, many thanks.

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Chris
I suspect that you could adapt the code in this post from Hans.

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I suspect you are right!
I hate On Error with a passion; it always seems to me to be a catch-all for unplanned events.
OTOH sending a file, any file, to Hans’s code and returning the error should tell me whether or not it was a shortcut, and I much prefer that than relying on a vaporous extent.

Thanks Don!

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