Close a MSI file handle after being downloaded from a website - vb.net

Question

I have a vsto add-in for outlook. There is a code where I download a MSI file from a website:
Public Sub DownloadMsiFile()
Try
Dim url As String = "https://www.website.com/ol.msi"
Dim wc As New WebClient()
wc.Headers.Add(HttpRequestHeader.UserAgent, "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;")
If File.Exists(My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi") Then
System.IO.File.Delete(My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi")
End If
wc.DownloadFile(url, My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi")
wc.Dispose()
Catch ex As Exception
MessageBox.Show("File couldn't be downloaded: " & ex.Message)
End Try
End Sub
And then I get the MSI version using the following function:
Function GetMsiVersion() As String
Try
Dim oInstaller As WindowsInstaller.Installer
Dim oDb As WindowsInstaller.Database
Dim oView As WindowsInstaller.View
Dim oRecord As WindowsInstaller.Record
Dim sSQL As String
oInstaller = CType(CreateObject("WindowsInstaller.Installer"), WindowsInstaller.Installer)
DownloadMsiFile()
If File.Exists(My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi") Then
oDb = oInstaller.OpenDatabase(My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi", 0)
sSQL = "SELECT `Value` FROM `Property` WHERE `Property`='ProductVersion'"
oView = oDb.OpenView(sSQL)
oView.Execute()
oRecord = oView.Fetch
Return oRecord.StringData(1).ToString()
Else
Return Nothing
End If
Catch ex As Exception
MessageBox.Show("File couldn't be accessed: " & ex.Message)
End Try
End Function
And then I do the comparison with the current dll version to see if there is a need to download a newer version or not:
Public Sub CheckOLUpdates()
Dim remoteVersion As String = GetMsiVersion()
Dim installedVersion As String = Assembly.GetExecutingAssembly().GetName().Version.ToString
If Not String.IsNullOrEmpty(remoteVersion) Then
Try
If String.Compare(installedVersion, remoteVersion) < 0 Then
Dim Result As DialogResult = MessageBox.Show("A newer version is available for download, do you want to download it now?", "OL", System.Windows.Forms.MessageBoxButtons.OKCancel, MessageBoxIcon.Question)
If Result = 1 Then
System.Diagnostics.Process.Start("http://www.website.com/update")
Else
Exit Sub
End If
Else
MessageBox.Show("You have the latest version installed!", "OL", MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
Catch ex As Exception
End Try
End If
End Sub
This works pretty well if this ran once. However if I try again to check for update, I would get the following error which happens while trying to delete the file in DownloadMsiFile() :
The process cannot access the file %temp%\ol.msi because it is being used by another process
If I use the sysinternals handle.exe utility to check the handles on this file I get the outlook process having a handle lock on this file:
handle.exe %temp%\ol.msi
Nthandle v4.30 - Handle viewer
Copyright (C) 1997-2021 Mark Russinovich
Sysinternals - www.sysinternals.com
OUTLOOK.EXE pid: 25964 type: File 4FC8: %temp%\ol.msi
I was wondering how can I close the handle to avoid this error? Any help is really appreciated

Answer 1

So here is what I have to do to close the handle. I have added the following lines after opening the MSI file:
Marshal.FinalReleaseComObject(oRecord)
oView.Close()
Marshal.FinalReleaseComObject(oView)
Marshal.FinalReleaseComObject(oDb)
oRecord = Nothing
oView = Nothing
oDb = Nothing
So my final code looked like the following:
Function GetMsiVersion() As String
Try
Dim oInstaller As WindowsInstaller.Installer
Dim oDb As WindowsInstaller.Database
Dim oView As WindowsInstaller.View
Dim oRecord As WindowsInstaller.Record
Dim sSQL As String
Dim Version As String
oInstaller = CType(CreateObject("WindowsInstaller.Installer"), WindowsInstaller.Installer)
DownloadMsiFile()
If File.Exists(My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi") Then
oDb = oInstaller.OpenDatabase(My.Computer.FileSystem.SpecialDirectories.Temp & "\ol.msi", 0)
sSQL = "SELECT `Value` FROM `Property` WHERE `Property`='ProductVersion'"
oView = oDb.OpenView(sSQL)
oView.Execute()
oRecord = oView.Fetch
Version = oRecord.StringData(1).ToString()
Marshal.FinalReleaseComObject(oRecord)
oView.Close()
Marshal.FinalReleaseComObject(oView)
Marshal.FinalReleaseComObject(oDb)
oRecord = Nothing
oView = Nothing
oDb = Nothing
Else
Version = Nothing
End If
Return Version
Catch ex As Exception
MessageBox.Show("File couldn't be accessed: " & ex.Message)
End Try
End Function