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Having issues with zip.WriteToMemory.

Mar 19 '15 at 13:25

I am using the 32 bit version of the zip component for .net 3.5. I have a linkbutton on a site when clicked will create a zip file in memory and download it to the user. This issue seems to happen when compressing very large files. The one I am testing has 750 MB in files. It does not always successfully compress the zip file. Most times it throws either a "specified argument was out of the range of valid values parameter name offset" error or "System.OutOfMemory" exception.

Here's the .net code i am using:

Protected Sub btnZip_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnZip.Click
    If Page.IsPostBack Then
        Dim iAppID As Integer = 0
        litMessage.Text = ""
            If Not Request.Params("edit") Is Nothing Then
                If IsNumeric(Request.Params("edit")) Then
                    iAppID = Request.Params("edit")
                End If
            End If

        Catch ex As Exception
            iAppID = 0
        End Try

        Dim zip As New Chilkat.Zip()

        Dim success As Boolean

        success = zip.UnlockComponent("<key>")
        If (success <> True) Then
            'MsgBox("Failed to unlock zip component")
            Response.Write("Failed to unlock zip component")
            Exit Sub
        End If

        '  NewZip initializes the zip object.  It does not write
        '  the file.  The "" file, in this case, will never be written.
        Dim dDate As Date = Date.Today
        Dim sFileName As String = "App-" & iAppID.ToString & "_" & Format(dDate, "MMM-dd-yyyy")
        success = zip.NewZip(sFileName & ".zip")
        If (success <> True) Then
            Exit Sub
        End If
        Dim oData As Data.DataSet
        Dim sFilePath As String = Application("PerformerApplication")

        sFilePath &= hidAppYear.Value & "/" & hidStatID.Value & "/"

        oData = Applications.GetMappedFiles(hidPerfAppID.Value)
        For Each oRow As Data.DataRow In oData.Tables(0).Rows
            If System.IO.File.Exists(sFilePath & oRow("FileName").ToString) = True Then
                success = zip.AppendOneFileOrDir(sFilePath & oRow("FileName").ToString, False)
                Dim entry As Chilkat.ZipEntry

                Dim sNewFileName As String = oRow("OriginalFileName").ToString.Replace(" ", "_")
                'Dim fFile As System.IO.FileInfo = New System.IO.FileInfo(sFilePath & oRow("FileName").ToString)
                entry = zip.GetEntryByName(oRow("FileName").ToString)
                If (entry Is Nothing) Then
                    litMessage.Text = ConjunctionJunction.WriteMessageBox("Problem: Failed to find entry in .zip")
                    Exit Sub
                End If
                'Dim sTestName As String = ""
                entry.FileName = sNewFileName '& fFile.Extension.ToLower
                litMessage.Text = ConjunctionJunction.WriteMessageBox("Problem: All the files are not found. Download aborted.")
                Exit Sub
            End If

        oData = Nothing

        Dim Data As Byte()
        Data = zip.WriteToMemory
        'binarywrite specified argument was out of the range of valid values parameter name offset

        If Data.Length > 0 Then
            Response.ContentType = "application/octet-stream"
            Response.AddHeader("Content-Length", Data.Length.ToString())
            Response.AddHeader("Content-Disposition", _
                               "attachment; filename=""" & zip.FileName & """")
            litMessage.Text = ConjunctionJunction.WriteMessageBox("Problem: Issue creating the zip file. Download aborted.")
            Exit Sub
        End If

    End If
End Sub

Here is the last error log:

    DllDate: Mar  6 2015
    UnlockPrefix: hiddenCode
    Username: PC
    Architecture: Little Endian; 32-bit
    Language: .NET 2.0
    VerboseLogging: 0
      oemCodePage: 437
      encryption: 0
      passwordProtected: 0
      totalSize64: 835371467
          Failed to allocate memory for output data buffer.
          ensureSz0: 199790978
          ensureSz: 299686467
          m_idx: 199759896
          size: 31074
          Failed to write compressed data to output file.
          Deflate source to output failed.
      Output failed.

I am not sure how to resolve this issue.

Accepted Answer

I think the only solution is to write the .zip to a temp file on the server and then stream the response from the temp file. After streaming the response, you may delete the temp file.

I found this information after Googling (not expecting to find a Chilkat-specific result, but found something I wrote a few years back..)

The information at the URL above mentions a separate FileAccess ActiveX DLL, but the FileAccess class/object is included within the Chilkat ActiveX DLL nowadays..