FIX: Crash in INET Control Downloading Page Multiple Times

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 5.0

SYMPTOMS

The Internet Transfer Control crashes if you call the Execute method that causes the GetChunk function to be called repeatedly.

This problem only occurs with the Execute method when GetChunk is called repeatedly, asking for small buffers (for instance, 1K), until the total download is retrieved. If GetChunk is called only once and asks for a very large buffer (for instance, 100K), the problem disappears.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q170365
   TITLE     : INFO: Visual Studio 97 Service Packs - What, Where, and Why

   ARTICLE-ID: Q171554
   TITLE     : INFO: Visual Basic 5.0 Fixes in Visual Studio 97
               Service Pack 2

MORE INFORMATION

Steps to Reproduce Behavior

1. Run Visual Basic or, if Visual Basic is already running, choose New Project from the File menu (ALT, F, N). Form1 is created by default.

2. Place an Internet Transfer Control (Inet1) on Form1 and add the following code:

        Private Sub Inet1_StateChanged(ByVal State As Integer)
           Dim strMess As String ' Message variable.
           Select Case State
           ' ... Other cases not shown.
   
           Case icResponseCompleted ' 12
               Dim vtData As Variant ' Data variable.
               Dim strData As String: strData = ""
               Dim bDone As Boolean: bDone = False
   
               ' Get first chunk.
               vtData = Inet1.GetChunk(1024, icString)
   
               Do While Not bDone
                   strData = Data & vtData
                   ' Get next chunk.
                   vtData = Inet1.GetChunk(1024, icString)
                   If Len(vtData) = 0 Then
                       bDone = True
                   End If
               Loop
   
               txtdata.Text = strData
   
         End Sub
   
   

3. Place a CommandButton (Command1) on Form1, and add the following code:

         Private Sub Command4_Click()
            Inet1.Execute "ftp://Tony's Server", "dir"
         End Sub
   
   

4. From the Run menu, click Start (ALT, R, S), or press the F5 key to run the program. Press the Command1 button multiple time to see the crash.

Keywords          : vb5all VS97FixlistSP3 VS97FixlistSP2 VB5FixlistSP2
Technology        : knInetDev
Version           : WINDOWS:5.0
Platform          : NT WINDOWS
Issue type        : kbbug
Solution Type     : kbfix kbservicepack