Вот че отцы советуют 
 
 
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Private Const GENERIC_WRITE = &H40000000
Private Const FILE_ATTRIBUTE_NORMAL = &H80
Private Const OPEN_EXISTING = 3
'
Private Const FILE_BEGIN = 0
Private Const FILE_CURRENT = 1
Private Const FILE_END = 2
'
Private Type SECURITY_ATTRIBUTES
  nLength As Long
  lpSecurityDescriptor As Long
  bInheritHandle As Long
End Type
'
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" ( _
    ByVal lpFileName As String, _
    ByVal dwDesiredAccess As Long, _
    ByVal dwShareMode As Long, _
    ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES, _
    ByVal dwCreationDisposition As Long, _
    ByVal dwFlagsAndAttributes As Long, _
    ByVal hTemplateFile As Long) As Long
    '
Private Declare Function SetFilePointer Lib "kernel32" ( _
    ByVal hFile As Long, _
    ByVal lDistanceToMove As Long, _
    lpDistanceToMoveHigh As Long, _
    ByVal dwMoveMethod As Long) As Long
    '
Private Declare Function SetEndOfFile Lib "kernel32" (ByVal hFile As Long) As Long
Удачи......