Uploading '.xlsx' or '.docx' to SharePoint 2007 from ASP.NET app causing file 'corruption'

Question

I have an ASP.NET application wrapped in SharePoint 2007 website. Within this application I allow users to create requests and they can also upload supporting files for the request. When a user uploads supporting docs of type .docx or .xlsx (the only two that I have found to become corrupt so far) they are becoming 'corrupted' in a sense that when I attempt to open them, I'm prompted with a message saying:

"Excel found unreadable content in 'Book1.xlsx'. Do you want to recover the contents of this workbook? If you trust the source of this workbook, click Yes"

When I click yes, it does repair the file and display the contents correctly, but this is unacceptable to the users. I don't even want them to have the problem.

Here is the code (VB.NET) for my upload click event:

Private Sub Upload_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnUpload.Click
Try
    Dim currentUser As SPUser = SPContext.Current.Web.AllUsers("SHAREPOINT\SYSTEM")
    Dim currentUserToken As SPUserToken = currentUser.UserToken
    Using currentSite As SPSite = New SPSite(SPContext.Current.Web.Url, currentUserToken)

        Using CurrentWeb As SPWeb = currentSite.OpenWeb
            CurrentWeb.AllowUnsafeUpdates = True

            Dim attachmentList As SPList = CurrentWeb.Lists("Requests")

            Dim item As SPListItem = attachmentList.GetItemById(CurrentRequestId)

            If FileUpload.PostedFile.ContentLength > Nothing And FileUpload.HasFile Then
                Dim fStream As Stream = FileUpload.PostedFile.InputStream
                Dim contents() As Byte = New Byte(fStream.Length) {}

                fStream.Read(contents, 0, CType(fStream.Length, Integer))
                fStream.Close()
                fStream.Dispose()

                Dim attachments As SPAttachmentCollection = item.Attachments
                Dim fileName As String = Path.GetFileName(FileUpload.PostedFile.FileName)
                attachments.Add(fileName, contents)
                item.Update()
            Else
                Page.ClientScript.RegisterStartupScript(Page.GetType(), "disp_msg", "<script type='text/javascript'>alert('The file contains 0 Bytes of data and will be deleted.'); </script>")
            End If
        End Using
    End Using
    DisplayAttachment(CurrentRequestId)
    btnSave.Focus()
Catch ex As Exception
    Page.ClientScript.RegisterStartupScript(Page.GetType(), "disp_msg", "<script type='text/javascript'>alert('Error Uploading File: " & ex.Message & "'); </script>")
End Try
End Sub

Any help would be appreciated. Thanks in advance.

Answer 1

The problem you have is in this line:

Dim contents() As Byte = New Byte(fStream.Length) {}

It should be

Dim contents() As Byte = New Byte(fStream.Length - 1) {}

The VB.NET arrays specify the upper bound - not the length - and since VB.NET is zero-based - the old line created one extra byte at the end.

This is typically not a problem, but docx and xlsx files are more sensitive to this extra byte.