FileReady Function

Private Function FileReady(strFileName As String) As Boolean
'***********************************************
' * Programmer Name : Jerry Barnett
' * Procedure Name : FileReady
' * Parameters : strFileName As String - 
' * Filename to check
' * Returns : TRUE - if the file exists and
' *   is not in use
' *   by any other process.
' *  FALSE - if the file is in use by
' *   another process, or does
' *   not exist.
'***********************************************
' * Comments : This function checks to 
' * see if a file is ready for use. It
' * tries to open the file for
' * exclusive use.
' * 
' * NOTE - An example of where this
' * function would be used is as
' * follows:
' * You have an application that needs
' * to process files as they are
' * created in a directory. However 
' * since they could be large files 
' * you don't want to start
' * processing the file before it 
' * is completely copied (or FTP'd)
' * into the directory. This function
' * will determine if the copy or FTP
' * is complete so that you can then
' * open the file for processing.
'************************************
' * The following Constants and 
' * Declares must be placed in the
' * Module DECLARES section.
'************************************
' *
' * Public Const SHARE_EXCLUSIVE = &H0
' * Public Const INVALID_HANDLE_VALUE = -1
' * Public Const ERROR_ALREADY_EXISTS = 183&
' * Public Const OPEN_EXISTING = 3
' * Public Const FILE_ATTRIBUTE_NORMAL = &H80
' * Public Const GENERIC_READ = &H80000000
' *
' * Public Type SECURITY_ATTRIBUTES
' *   nLength As Long
' *   lpSecurityDescriptor As Long
' *   bInheritHandle As Long
' * End Type
' *
' * Public Declare Function GetLastError _
' * Lib "kernel32" () As Long
' *
' * Public Declare Function CreateFile Lib _
' * "kernel32" Alias "CreateFileA" _
' * (ByVal lpFileName As String, _
' *  ByVal dwDesiredAccess As Long, _
' *  ByVal dwShareMode As Long, _
' *  pSecurityAttributes As SECURITY_ATTRIBUTES, _
' *  ByVal dwCreationDisposition As Long, _
' *  ByVal dwFlagsAndAttributes As Long, _
' *  ByVal hTemplateFile As Long) As Long
' *
' * Public Declare Function CloseHandle Lib _
' * "kernel32" (ByVal hObject As Long) As Long
' *
'************************************************
 Dim lReturnCode As Long
 Dim typAtrib As SECURITY_ATTRIBUTES
 ' Try to open the file for exclusive use
 lReturnCode = CreateFile(strFileName, _
    GENERIC_READ, _
    SHARE_EXCLUSIVE, _
    typAtrib, _
    OPEN_EXISTING, _
    FILE_ATTRIBUTE_NORMAL, 0)
 If lReturnCode = INVALID_HANDLE_VALUE Then
 ' Failed exclusive use of file (File not ready)
 FileReady = False
 Exit Function ' Exit function
 End If
 ' File exists and is ready, so close the file
 lReturnCode = CloseHandle(lReturnCode)
 ' Return True (File is Ready)
 FileReady = True
End Function
'************************************************
' A Sample of how to use this function:
Private Sub Main()
 Dim lCount as Long
 Dim Const MAXCOUNT = 5 ' Actually this would be in
 ' the module declares section
 Do While Not FileReady("FileToCheckFor.txt") Then
 lCount = lCount + 1
 ' ...... wait some predetermined amount
 ' of time .....
 If lCount = MAXCOUNT Then
  Msg "File Not Ready! Maximum try's exceeded!"
  End
 End If
 Loop
 Msg "File can now pe processed!"
 ' .... Do your processing code to work
 ' with the file.
End Sub