dtecting if a file is presently open

[JimMuglia]

Greetings,

OK, here;'s the pseudocode. Are there command or properties to make it a reality?

' open a given file
' if the file is already opened by another user then
'MsgBox "Another user is presently using this file.
Data corruption may occur."
'end if

For example is there some file property I can evaluate to determine if the file is presently open?

Thank you,
Jim

[phinds]

just open the file. If you get an error #55, then it is already open and you will not be allowed to open it so "data corruption" is not an issue as you can't write to a file that someone else has open.

[JimMuglia]

Originally posted by phinds
just open the file. If you get an error #55, then it is already open and you will not be allowed to open it so "data corruption" is not an issue as you can't write to a file that someone else has open.

What if they are using Terminal Services?

[CVMichael]

Delete the file , and if you can delete it, then it's not open

[CVMichael]

Actually, a safer way, would be to rename the file... and if you can rename it, then it's not open

[Shawn N]

'Determine whether a file is already open or not
Private Declare Function lOpen Lib "kernel32" Alias "_lopen" (ByVal lpPathName As String, ByVal iReadWrite As Long) As Long
Private Declare Function lClose Lib "kernel32" Alias "_lclose" (ByVal hFile As Long) As Long
Private Function IsFileAlreadyOpen(FileName As String) As Boolean
    Dim hFile As Long
    Dim lastErr As Long
    ' Initialize file handle and error variable.
    hFile = -1
    lastErr = 0
    ' Open for for read and exclusive sharing.
    hFile = lOpen(FileName, &H10)
    ' If we couldn't open the file, get the last error.
    If hFile = -1 Then
        lastErr = Err.LastDllError
    Else
        ' Make sure we close the file on success.
        lClose (hFile)
    End If
    ' Check for sharing violation error.
    sFileAlreadyOpen = (hFile = -1) And (lastErr = 32)
End Function
Private Sub Form_Load()
    'example by Matthew Gates ([email protected])
    MsgBox IsFileAlreadyOpen("c:\autoexec.bat")
End Sub

[CVMichael]

I might be wrong, but if you open the file with this flag: FILE_SHARE_READ_WRITE, then it means that the file can be opened in the same time with another program ? So if that flag is used then the second Open will not return an error.

[randem]

JimMuglia


If you open the file exclusive no sharing, you will either open the file or get an error if it is already open.