Question

I’m developing a asp.net webforms website using vb.net. In that list of files displayed in a gridview as links, when clicked on a link it calls OpenFile method. This code I found on the web is used to download file stored in webserver to client, this works fine for images but when I try to download .docx or .xlsx file it gives an error
in the line "Response.BinaryWrite(btFile)", but downloads the file. Given below is shortend version of the actual code

Page Code:

Protected Sub grvItemAttachments_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles grvItemAttachments.RowCommand
    Try
        If e.CommandName = "Open" Then
            FileOpener.OpenFile(fileNameWithPath)
        End If
    Catch ex As Exception
        ErrHandler.WriteError(ex.Message)
    End Try
 End Sub

File Opener Code:

Public Shared Sub OpenFile(fileNameWithPath as string)
    Dim file As New FileInfo(fileNameWithPath)
    Dim fs As System.IO.FileStream = Nothing
    fs = System.IO.File.Open(fileNameWithPath, System.IO.FileMode.Open)
    Dim btFile As Byte() = New Byte(fs.Length - 1) {}
    fs.Read(btFile, 0, Convert.ToInt32(fs.Length))
    fs.Close()
    Response.AddHeader("Content-disposition", "attachment; filename=" & FileName)
    Response.ContentType = GetFileType(file.Extension.ToLower()) 
    Response.BinaryWrite(btFile)
    Response.End()
End Sub

Error Message:

System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values." & vbCrLf & "Parameter name: offset" & vbCrLf & "   at System.Web.HttpResponseStream.Write(Byte[] buffer, Int32 offset, Int32 count)" & vbCrLf & "   at System.Web.HttpResponse.BinaryWrite(Byte[] buffer)" & vbCrLf & "   at FileOpener.OpenFile(String FileName, String FolderName) in D:\Projects\VSS Projects\PIL WebSite\App_Code\Common\FileOpener.vb:line 25" & vbCrLf & "   at Web_RTOView.grvItemAttachments_RowCommand(Object sender, GridViewCommandEventArgs e) in D:\Projects\VSS Projects\PIL WebSite\Web\RTOView.aspx.vb:line 310}
------
grvItemAttachments_RowCommand
Error Message: Specified argument was out of the range of valid values.
Parameter name: offset

Any idea how to solve this issue?

Answer 1

Why are you initializing your byte array to Length-1? Shouldn’t it be exact size as Length?
In fact, you try to read the contents of the file from 0 to Length but your byte array length is Length-1