Access Denied Error while changing network Printer Settings using "SetPrinter" from VB.NET

Question

Hello,
I am developing a Word Add-in using VB.Net (VSTO 2010), where I would like to control some of the printer settings (such as duplex, print quality and orientation). I am trying to use the Winspool.drv's SetPrinter, but I get an "Access Denied" error when I call the SetPrinter procedure on a networked printer. The program works on my local machine where I am able to change the printer settings for a printer connected to my machine. However the Access Denied error occurs on the test machine, (Where the user has lower privileges - the user does not have admin privileges on the printer).

Word 2010 is able to change duplex settings on the test machine, so I'm pretty sure I am not doing something right. I have tried with different access levels to no avail. I would appreciate it if someone could help me out here.

I am using  VSTO 2010 on Word 2010 and Windows 7 64 bit for this add-in. Here is the code that I am using. I built this code following the example from this article http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/q140/2/85.asp&NoWebContent=1.

The steps being followed here are:
- Use OpenPrinter to get a handle to the printer
- Call GetPrinter to get the size of the buffer required for the PRINTER_INFO_2 structure
- Allocate the memory
- Call GetPrinter again to fill in the buffer.
- If the DEVMODE structure did not get filled in by GetPrinter, use DocumentProperties
  - Call DocumentProperties once to get the size of memory required for DEVMODE structure
  - Allocate the memory for the DEVMODE structure
  - Call DocumentProperties once again to fill in the DEVMODE structure
- Make the duplex flag in the DEVMODE structure
- Call DocumentProperties to merge the changes in the DEVMODE settings with the current settings.
- Call SetPrinter to make the changes.
- Close the printer handle
- Release the memory allocated.

Imports System.Runtime.InteropServices
Imports System.Collections
Imports System.ComponentModel

Public Class ModifyPrinter
#Region "Structures Definitions"
 <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
 Private Structure PRINTER_INFO_2

 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pServerName As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pPrinterName As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pShareName As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pPortName As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pDriverName As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pComment As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pLocation As String

 Public pDevMode As IntPtr

 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pSepFile As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pPrintProcessor As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pDatatype As String
 <MarshalAs(UnmanagedType.LPTStr)> _
 Public pParameters As String

 Public pSecurityDescriptor As IntPtr
 Public Attributes As Integer
 Public Priority As Integer
 Public DefaultPriority As Integer
 Public StartTime As Integer
 Public UntilTime As Integer
 Public Status As Integer
 Public cJobs As Integer
 Public AveragePPM As Integer

 End Structure
 <Flags()> _
 Enum DM As Integer
 Orientation = &H1
 PaperSize = &H2
 PaperLength = &H4
 PaperWidth = &H8
 Scale = &H10
 Position = &H20
 NUP = &H40
 DisplayOrientation = &H80
 Copies = &H100
 DefaultSource = &H200
 PrintQuality = &H400
 Color = &H800
 Duplex = &H1000
 YResolution = &H2000
 TTOption = &H4000
 Collate = &H8000
 FormName = &H10000
 LogPixels = &H20000
 BitsPerPixel = &H40000
 PelsWidth = &H80000
 PelsHeight = &H100000
 DisplayFlags = &H200000
 DisplayFrequency = &H400000
 ICMMethod = &H800000
 ICMIntent = &H1000000
 MediaType = &H2000000
 DitherType = &H4000000
 PanningWidth = &H8000000
 PanningHeight = &H10000000
 DisplayFixedOutput = &H20000000
 End Enum
 <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
 Public Structure DEVMODE
 Public Const CCHDEVICENAME As Integer = 32
 Public Const CCHFORMNAME As Integer = 32

 <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=CCHDEVICENAME)> _
 Public dmDeviceName As String
 Public dmSpecVersion As Short
 Public dmDriverVersion As Short
 Public dmSize As Short
 Public dmDriverExtra As Short
 Public dmFields As DM

 Public dmOrientation As Short
 Public dmPaperSize As Short
 Public dmPaperLength As Short
 Public dmPaperWidth As Short

 Public dmScale As Short
 Public dmCopies As Short
 Public dmDefaultSource As Short
 Public dmPrintQuality As Short
 Public dmColor As Short
 Public dmDuplex As Short
 Public dmYResolution As Short
 Public dmTTOption As Short
 Public dmCollate As Short
 <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=CCHFORMNAME)> _
 Public dmFormName As String
 Public dmLogPixels As Short
 Public dmBitsPerPel As Integer ' Declared wrong in the full framework
 Public dmPelsWidth As Integer
 Public dmPelsHeight As Integer
 Public dmDisplayFlags As Integer
 Public dmDisplayFrequency As Integer

 Public dmICMMethod As Integer
 Public dmICMIntent As Integer
 Public dmMediaType As Integer
 Public dmDitherType As Integer
 Public dmReserved1 As Integer
 Public dmReserved2 As Integer
 Public dmPanningWidth As Integer
 Public dmPanningHeight As Integer

 Public dmPositionX As Integer ' Using a PointL Struct does not work
 Public dmPositionY As Integer
 End Structure
 <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
 Public Structure PRINTER_DEFAULTS
 Public pDatatype As IntPtr
 Public pDevMode As IntPtr
 Public DesiredAccess As Integer
 End Structure

#End Region
#Region "Constants"
 Private Enum AccessMask
 READ_CONTROL = &H20000
 WRITE_DAC = &H40000
 PRINTER_ACCESS_USE = &H8
 PRINTER_ALL_ACCESS = 983052
 PRINTER_WRITE = 131080
 PRINTER_ACCESS_ADMINISTER = 4
 SERVER_EXECUTE = 131074
 SERVER_WRITE = 131075
 SERVER_ALL_ACCESS = 983043

 End Enum

 Private Const PRINTER_ACCESS_CODE = (AccessMask.READ_CONTROL Or AccessMask.PRINTER_ACCESS_USE)
 Private Const ERROR_INSUFFICIENT_BUFFER = 122

 Private Const DUPLEX_LONG_EDGE As Integer = 2
 Private Const DRAFT_RESOLUTION As Integer = 300
 Private Const DM_DUPLEX = &H1000&

 Private Enum DocProperties
 DM_UPDATE = 1
 DM_COPY = 2
 DM_PROMPT = 4
 DM_MODIFY = 8

 DM_IN_BUFFER = DM_MODIFY
 DM_IN_PROMPT = DM_PROMPT
 DM_OUT_BUFFER = DM_COPY
 DM_OUT_DEFAULT = DM_UPDATE

 End Enum
#End Region
#Region "DLL Import Statements"
 <DllImport("winspool.drv", _
  EntryPoint:="OpenPrinterA", _
  ExactSpelling:=True, _
  SetLastError:=True, _
  CallingConvention:=CallingConvention.StdCall, _
  CharSet:=CharSet.Ansi)> _
 Private Shared Function OpenPrinter(ByVal pPrinterName As String, _
     ByRef hPrinter As IntPtr, _
     ByRef pDefault As PRINTER_DEFAULTS) As Boolean
 End Function

 <DllImport("winspool.Drv", _
  EntryPoint:="GetPrinterA", _
  SetLastError:=True, _
  CharSet:=CharSet.Ansi, _
  ExactSpelling:=True, _
  CallingConvention:=CallingConvention.StdCall)> _
 Private Shared Function GetPrinter(ByVal hPrinter As IntPtr, _
     ByVal dwLevel As Int32, _
     ByVal pPrinter As IntPtr, _
     ByVal dwBuf As Int32, _
     ByRef dwNeeded As Int32) As Boolean
 End Function
 <DllImport("winspool.Drv", _
  EntryPoint:="DocumentPropertiesA", _
  SetLastError:=True, _
  ExactSpelling:=True, _
  CallingConvention:=CallingConvention.StdCall, _
  CharSet:=CharSet.Ansi)> _
 Private Shared Function DocumentProperties(ByVal hwnd As IntPtr, _
      ByVal hPrinter As IntPtr, _
      <MarshalAs(UnmanagedType.LPWStr)> ByVal pDeviceName As String, _
      ByVal pDevModeOutput As IntPtr, _
      ByVal pDevModeInput As IntPtr, _
      ByVal fMode As Integer) As Integer
 End Function

 <DllImport("winspool.Drv", _
  CharSet:=CharSet.Ansi, _
  EntryPoint:="ClosePrinter", _
  SetLastError:=True, _
  ExactSpelling:=True, _
  CallingConvention:=CallingConvention.StdCall)> _
 Private Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Boolean
 End Function

 <DllImport("winspool.Drv", _
  EntryPoint:="SetPrinterA", _
  SetLastError:=True, _
  CharSet:=CharSet.Ansi, _
  ExactSpelling:=True, _
  CallingConvention:=CallingConvention.StdCall)> _
 Private Shared Function SetPrinter(ByVal hPrinter As IntPtr, _
     ByVal Level As UInteger, _
     ByVal pPrinter As Integer, _
     ByVal Command As UInteger) As Boolean
 End Function
#End Region
 ''' <summary>
 ''' Changes the duplex setting of the passed in printer using the Winspool.drv class.
 ''' </summary>
 ''' <param name="psPrinterName"></param>
 ''' <returns></returns>
 ''' <remarks></remarks>
 Public Function SetPrinterDuplex(ByVal psPrinterName As String) As Boolean
 Dim bStatus As Boolean = True
 Dim ptrPrinter, ptrPrinterInfo, ptrDevMode As System.IntPtr
 Dim stPrinterInfo As PRINTER_INFO_2
 Dim pd As New PRINTER_DEFAULTS()
 Dim iBytesNeeded, iLastError, iStatus As Integer
 Dim dm As DEVMODE

 ' Open a handle to the printer
 pd.pDatatype = 0
 pd.pDevMode = 0
 pd.DesiredAccess = PRINTER_ACCESS_CODE
 bStatus = OpenPrinter(psPrinterName, ptrPrinter, pd)

 If bStatus = False Then
  ' Close the printer and exit.
  iLastError = Marshal.GetLastWin32Error()
  MsgBox("Error while calling OpenPrinter")
  Throw New Win32Exception(iLastError)
 End If

 ' First call to GetPrinter to get memory size needed for PRINTER_INFO_2 structure. This call will
 ' return an insufficient buffer error. If GetPrinter fails for any other reason, then exit the process.
 bStatus = GetPrinter(ptrPrinter, 2, Nothing, 0, iBytesNeeded)
 iLastError = Marshal.GetLastWin32Error()

 If bStatus = False And iLastError <> ERROR_INSUFFICIENT_BUFFER Then
  ' Close printer and exit
  iLastError = Marshal.GetLastWin32Error()
  MsgBox("Error on first call to GetPrinter")
  ClosePrinter(ptrPrinter)
  Throw New Win32Exception(iLastError)
 End If

 ' Allocate the required amount of space
 ptrPrinterInfo = Marshal.AllocCoTaskMem(iBytesNeeded)

 ' Second call to GetPrinter to get all the current settings, so we can modify only the settings
 ' that we are interested in changing.
 bStatus = GetPrinter(ptrPrinter, 2, ptrPrinterInfo, iBytesNeeded, iBytesNeeded)
 If bStatus = False Then

  iLastError = Marshal.GetLastWin32Error()
  MsgBox("Error with 2nd GetPrinter call")

  ClosePrinter(ptrPrinter)
  Marshal.FreeCoTaskMem(ptrPrinterInfo)

  Throw New Win32Exception(iLastError)
 End If


 ' Convert the pointer to PRINTER_INFO_2 to the structure.
 stPrinterInfo = DirectCast(Marshal.PtrToStructure(ptrPrinterInfo, GetType(PRINTER_INFO_2)), PRINTER_INFO_2)

 ' If GetPrinter did not fill in the DEVMODE, then try to get it from DocumentProperties.
 If stPrinterInfo.pDevMode = IntPtr.Zero Then
  iBytesNeeded = 0

  ' Call Document Properties once to get the size of the buffer required to 
  iBytesNeeded = DocumentProperties(IntPtr.Zero, ptrPrinter, psPrinterName, IntPtr.Zero, IntPtr.Zero, 0)

  ' If the call failed, then close the printer, release the memory and throw an error
  If iBytesNeeded <= 0 Then
  iLastError = Marshal.GetLastWin32Error()
  ClosePrinter(ptrPrinter)
  Marshal.FreeCoTaskMem(ptrPrinterInfo)
  MsgBox("Error during 1st call to DocumentProperties")
  Throw New Win32Exception(iLastError)
  End If

  ' Allocate the memory 
  ptrDevMode = Marshal.AllocCoTaskMem(iBytesNeeded)

  ' Call DocumentProperties again to populate the DEVMODE properties
  iStatus = DocumentProperties(IntPtr.Zero, ptrPrinter, psPrinterName, ptrDevMode, IntPtr.Zero, DocProperties.DM_OUT_BUFFER)
  If iStatus <> 0 Then
  iLastError = Marshal.GetLastWin32Error()
  ClosePrinter(ptrPrinter)
  Marshal.FreeCoTaskMem(ptrPrinterInfo)
  Marshal.FreeCoTaskMem(ptrDevMode)
  MsgBox("Error during 2nd call to DocumentProperties")
  Throw New Win32Exception(iLastError)
  End If

  stPrinterInfo.pDevMode = ptrDevMode
  'Marshal.StructureToPtr(stPrinterInfo, ptrPrinterInfo, True)

 End If

 ' If the driver doesn't support the duplex change, then inform the user and exit.

 dm = DirectCast(Marshal.PtrToStructure(stPrinterInfo.pDevMode, GetType(DEVMODE)), DEVMODE)
 If Not Convert.ToBoolean(dm.dmFields And DM_DUPLEX) Then
  Return False
 End If

 ' Change the duplex flag in DEVMODE.
 dm.dmDuplex = DUPLEX_LONG_EDGE

 ' Call DocumentProperties once again to update the drive dependent part of DEVMODE.
 iStatus = DocumentProperties(IntPtr.Zero, ptrPrinter, psPrinterName, _
     stPrinterInfo.pDevMode, stPrinterInfo.pDevMode, _
     DocProperties.DM_IN_BUFFER Or DocProperties.DM_OUT_BUFFER)
 If iStatus = 0 Then
  iLastError = Marshal.GetLastWin32Error()
  MsgBox("Error calling Document Properties to update driver dependent parts of DEVMODE")
  ClosePrinter(ptrPrinter)
  Marshal.FreeCoTaskMem(ptrPrinterInfo)
  Marshal.FreeCoTaskMem(ptrDevMode)
  Throw New Win32Exception(iLastError)
 End If

 Marshal.StructureToPtr(stPrinterInfo, ptrPrinterInfo, False)

 ' Set the security descriptor to 0 since it's not being used.
 stPrinterInfo.pSecurityDescriptor = IntPtr.Zero
 bStatus = SetPrinter(ptrPrinter, 2, ptrPrinterInfo, 0)

 If bStatus = False Then

  iLastError = Marshal.GetLastWin32Error()
  MsgBox("Error calling SetPrinter")
  ClosePrinter(ptrPrinter)
  Marshal.FreeCoTaskMem(ptrPrinterInfo)
  Marshal.FreeCoTaskMem(ptrDevMode)
  Throw New Win32Exception(iLastError)
 Else
  ClosePrinter(ptrPrinter)
  Marshal.FreeCoTaskMem(ptrPrinterInfo)
  Marshal.FreeCoTaskMem(ptrDevMode)
  Return True

 End If
 End Function
End Class

Thanks

Vikram

Answer 1

Hello Vikram,

Thanks for your post.

Please check this article about changing Printer settings using Windows API which describes how to handle this similar error. Please have a try and let us know the situatin on your side.

http://www.lessanvaezi.com/changing-printer-settings-using-the-windows-api/
(Changing Printer settings using the Windows API)

"In my testing, this worked fine on a local printer but when trying to change the settings on a network printer I was getting “access denied” errors. After some investigation, I got an explanation for what was happening. The following two articles provided the needed insight:

If you ask for STANDARD_RIGHTS_REQUIRED, you may as well ask for the moon
http://blogs.msdn.com/oldnewthing/archive/2008/02/27/7912126.aspx

Changing printer settings using C# (also see one of the first comments in the thread)
http://www.codeproject.com/KB/dotnet/NET_Printer_Library.aspx?display=PrintAll "

If you have any concerns, please feel free to follow up.

Have a nice day.

Best regards

---

Liliane Teng [MSFT]
MSDN Community Support | Feedback to us
Get or Request Code Sample from Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 2

Hi Liliane,

Thanks for your response. I went through the links that you provided and that still doesn't seem to resolve the problem. I cannot change the printer settings if I don't use PRINTER_ALL_ACCESS. Since asking for All Access is not a good idea (and not supported in an network environment), the only way for this work is to use the lower privileges (READ_CONTROL Or PRINTER_ACCESS_USE).

One thing I discovered during my testing is that when I use VBA (the code listed in Lessan Vaezi's blog), I can use the lower privileges setting of PRINTER_NORMAL_ACCESS and change the settings on the network printer, but I cannot change it from VB.NET. I am completely baffled by this. What Is the difference between calling SetPrinter from VBA and VB.NET?

Thanks
Vikram

Answer 3

1)      Could you let me know the exact line of code?

2)      Does the issue happen on 32-bit machines?

---

--Trevor H.
Send files to Hotmail.com: "MS_TREVORH"

Answer 4

 

1)      Could you let me know the exact line of code?

2)      Does the issue happen on 32-bit machines?

---

--Trevor H.
Send files to Hotmail.com: "MS_TREVORH"

1. The error occurs in line number 352 (bStatus = SetPrinter(ptrPrinter, 2, ptrPrinterInfo, 0)). 

2. I haven't tried this on 32 bit machines, but I will run a test to find out and let you know.

 

Thanks for your help.

Vikram

Answer 5

Do you need more help?

---

--Trevor H.
Send files to Hotmail.com: "MS_TREVORH"

Answer 6

Yes, I am still not able to figure this out. I did try it out on a 32 bit machine and it does work on a local printer. I have to try this out on a network printer.

 

Thanks for your help
Vikram

Answer 7

Please...

1) Use PRINTER_INFO_9 instead of PRINTER_INFO_2.
2) pd.DesiredAccess = PRINTER_ACCESS_USE

... and let us know.

---

--Trevor H.
Send files to Hotmail.com: "MS_TREVORH"

Answer 8

Hi Trevor,

Sorry for the delay in the reply, but I tried using PRINTER_INFO_9 and PRINTER_ACCESS_USE and it crashed Word. I am not sure if that is the answer. Here is the definition for PRINTER_INFO_9 that I used:

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _
  Private Structure PRINTER_INFO_9
    Public pDevMode As IntPtr
  End Structure

Thanks for your help.

Vikram

Answer 9

Hello Vikram,

could you solve your problem? I am facing exactly the same problems ... Using Printer_Info_2 leads to Access denied errors, using Printer_Info_9 crashes the windows explorer (further investigations have shown that after calling SetPrinter with Printer_Info_9 any call to OpenPrinter (e.g. from Word or Acrobat) hangs.)

Answer 10

This:

For the PRINTER_INFO_2 and PRINTER_INFO_3 structures that contain a pointer to a security descriptor, the function can set only those components of the security descriptor that the caller has permission to modify. To set particular security descriptor components, you must specify the necessary access rights when you call the OpenPrinter or OpenPrinter2 function to retrieve a handle to the printer. The following table shows the access rights required to modify the various security descriptor components.

Access permission	Security descriptor component
WRITE_OWNER	Owner Primary group
WRITE_DAC	Discretionary access-control list (DACL)
ACCESS_SYSTEM_SECURITY	System access-control list (SACL)

Means that you must open a handle with WRITE_DAC and WRITE_OWNER if you want to use PRINTER_INFO_2.

For GetPrinter you will need READ_CONTROL and PRINTER_ACCESS_USE

This lets me switch between long edge and top edge (1 and 2), I can't set 0 for some reason.

Option Strict On
Option Explicit On
Option Infer Off

Imports System.Runtime.InteropServices
Imports System.Collections
Imports System.ComponentModel
Imports ConsoleApplication8.Consts

Public Class ModifyPrinter

    Public Shared Sub Main()
        Dim mp As New ModifyPrinter
        mp.SetPrinterDuplex("HP LaserJet P2050 Series PCL6")
    End Sub

    <DllImport("winspool.Drv", CharSet:=CharSet.Ansi, SetLastError:=True)> _
    Private Shared Function OpenPrinter(ByVal pPrinterName As String, _
     ByRef hPrinter As IntPtr, _
     ByRef pDefault As PRINTER_DEFAULTS) As Boolean
    End Function

    <DllImport("winspool.Drv", CharSet:=CharSet.Ansi, SetLastError:=True)> _
    Private Shared Function GetPrinter(ByVal hPrinter As IntPtr, _
     ByVal dwLevel As Int32, _
     ByVal pPrinter As IntPtr, _
     ByVal dwBuf As Int32, _
     ByRef dwNeeded As Int32) As Boolean
    End Function

    <DllImport("winspool.Drv", CharSet:=CharSet.Ansi, SetLastError:=True)> _
    Private Shared Function DocumentProperties(ByVal hwnd As IntPtr, _
      ByVal hPrinter As IntPtr, _
      ByVal pDeviceName As String, _
      ByVal pDevModeOutput As IntPtr, _
      ByVal pDevModeInput As IntPtr, _
      ByVal fMode As Integer) As Integer
    End Function

    <DllImport("winspool.Drv", CharSet:=CharSet.Ansi, SetLastError:=True)> _
    Private Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function

    <DllImport("winspool.Drv", CharSet:=CharSet.Ansi, SetLastError:=True)> _
    Private Shared Function SetPrinter(ByVal hPrinter As IntPtr, _
     ByVal Level As UInteger, _
     ByVal pPrinter As IntPtr, _
     ByVal Command As UInteger) As Boolean
    End Function

    Friend Function SetPrinterDuplex(ByVal psPrinterName As String) As Boolean
        Dim ptrPrinter, ptrPrinterInfo, ptrDevMode As System.IntPtr
        Dim iBytesNeeded, iLastError, iStatus As Integer
        Dim pd As New PRINTER_DEFAULTS()
        ' So - this is different - we need READ_CONTROL, PRINTER_ACCESS_USE to read stuff.
        ' And we need PRINTER_ACCESS_ADMINISTER, WRITE_DAC, WRITE_OWNER to set stuff.
        ' Seems like overkill - I'd go with using PRINTER_INFO_9
        pd.DesiredAccess = AccessMask.READ_CONTROL Or AccessMask.PRINTER_ACCESS_USE Or AccessMask.PRINTER_ACCESS_ADMINISTER Or AccessMask.WRITE_DAC Or AccessMask.WRITE_OWNER
        Try
            Dim bStatus As Boolean = OpenPrinter(psPrinterName, ptrPrinter, pd)
            If bStatus = False Then Throw New Win32Exception()
            bStatus = GetPrinter(ptrPrinter, 2, Nothing, 0, iBytesNeeded)
            iLastError = Marshal.GetLastWin32Error()
            If bStatus = False AndAlso iLastError <> ERROR_INSUFFICIENT_BUFFER Then Throw New Win32Exception()
            ptrPrinterInfo = Marshal.AllocHGlobal(iBytesNeeded)
            bStatus = GetPrinter(ptrPrinter, 2, ptrPrinterInfo, iBytesNeeded, iBytesNeeded)
            If bStatus = False Then Throw New Win32Exception()
            Dim stPrinterInfo As PRINTER_INFO_2 = DirectCast(Marshal.PtrToStructure(ptrPrinterInfo, GetType(PRINTER_INFO_2)), PRINTER_INFO_2)
            Dim dm As DEVMODE = DirectCast(Marshal.PtrToStructure(stPrinterInfo.pDevMode, GetType(DEVMODE)), DEVMODE)
            If Not Convert.ToBoolean(dm.dmFields And DM_DUPLEX) Then
                Return False
            End If
            Console.WriteLine("Duplex before: " & dm.dmDuplex) ' run again to see if it's changed
            dm.dmDuplex = 2 ' valid values  1 & 2
            Console.WriteLine("Trying to set to: " & dm.dmDuplex)
            ' jo0ls added this to copy the devmode back to memory:
            Marshal.StructureToPtr(dm, stPrinterInfo.pDevMode, True)

            iStatus = DocumentProperties(IntPtr.Zero, ptrPrinter, psPrinterName, _
                stPrinterInfo.pDevMode, stPrinterInfo.pDevMode, _
                DocProperties.DM_IN_BUFFER Or DocProperties.DM_OUT_BUFFER)
            If iStatus = 0 Then Throw New Win32Exception()
            Marshal.StructureToPtr(stPrinterInfo, ptrPrinterInfo, False)
            stPrinterInfo.pSecurityDescriptor = IntPtr.Zero
            bStatus = SetPrinter(ptrPrinter, 2, ptrPrinterInfo, 0)
            If bStatus = False Then Throw New Win32Exception
            Return True
        Finally
            If ptrPrinter <> IntPtr.Zero Then ClosePrinter(ptrPrinter)
            If ptrPrinterInfo <> IntPtr.Zero Then Marshal.FreeHGlobal(ptrPrinterInfo)
            If ptrDevMode <> IntPtr.Zero Then Marshal.FreeHGlobal(ptrDevMode)
        End Try
    End Function

End Class

The stuff that's not in that listing are in Vikram's post earlier. SetPrinter should have an IntPtr for pPrinter, so that's changed. Also the original code does not write the devmode structure back to memory after setting the desired duplex value - so there's a line required to do that.

Answer 11

For printer_info_9 you don't need as many rights.

    <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
    Friend Structure PRINTER_INFO_9
        Public pDevMode As IntPtr
    End Structure

    Friend Function SetPrinterDuplex(ByVal psPrinterName As String) As Boolean
        Dim ptrPrinter, ptrPrinterInfo, ptrDevMode As System.IntPtr
        Dim iBytesNeeded, iStatus As Integer
        Dim pd As New PRINTER_DEFAULTS
        pd.DesiredAccess = AccessMask.READ_CONTROL Or AccessMask.PRINTER_ACCESS_USE Or AccessMask.PRINTER_ACCESS_ADMINISTER
        Try
            Dim bStatus As Boolean = OpenPrinter(psPrinterName, ptrPrinter, pd)
            If bStatus = False Then Throw New Win32Exception()
            bStatus = GetPrinter(ptrPrinter, 9, Nothing, 0, iBytesNeeded)
            If bStatus = False AndAlso Marshal.GetLastWin32Error() <> ERROR_INSUFFICIENT_BUFFER Then Throw New Win32Exception()
            ptrPrinterInfo = Marshal.AllocHGlobal(iBytesNeeded)
            bStatus = GetPrinter(ptrPrinter, 9, ptrPrinterInfo, iBytesNeeded, iBytesNeeded)
            If bStatus = False Then Throw New Win32Exception()
            Dim stPrinterInfo As PRINTER_INFO_9 = DirectCast(Marshal.PtrToStructure(ptrPrinterInfo, GetType(PRINTER_INFO_9)), PRINTER_INFO_9)
            Dim dm As DEVMODE = DirectCast(Marshal.PtrToStructure(stPrinterInfo.pDevMode, GetType(DEVMODE)), DEVMODE)
            If Not Convert.ToBoolean(dm.dmFields And DM_DUPLEX) Then Return False
            Console.WriteLine("Duplex before: " & dm.dmDuplex) ' run again to see if it's changed
            dm.dmDuplex = 1 ' DMDUP_SIMPLEX = 1, DMDUP_VERTICAL = 2, DMDUP_HORIZONTAL = 3
            Console.WriteLine("Trying to set to: " & dm.dmDuplex)
            Marshal.StructureToPtr(dm, stPrinterInfo.pDevMode, False)
            iStatus = DocumentProperties(IntPtr.Zero, ptrPrinter, psPrinterName, _
                stPrinterInfo.pDevMode, stPrinterInfo.pDevMode, _
                DocProperties.DM_IN_BUFFER Or DocProperties.DM_OUT_BUFFER)
            If iStatus = 0 Then Throw New Win32Exception()
            bStatus = SetPrinter(ptrPrinter, 9, ptrPrinterInfo, 0)
            If bStatus = False Then Throw New Win32Exception
            Return True
        Finally
            If ptrPrinter <> IntPtr.Zero Then ClosePrinter(ptrPrinter)
            If ptrPrinterInfo <> IntPtr.Zero Then Marshal.FreeHGlobal(ptrPrinterInfo)
            If ptrDevMode <> IntPtr.Zero Then Marshal.FreeHGlobal(ptrDevMode)
        End Try
    End Function

I didn't put the constants in the last post:

Friend Enum AccessMask
    PRINTER_ACCESS_ADMINISTER = 4
    PRINTER_ACCESS_USE = 8
    READ_CONTROL = &H20000
    WRITE_DAC = &H40000
    WRITE_OWNER = &H80000
End Enum

Answer 12

For network printers try

' SERVER_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED | SERVER_ACCESS_ADMINISTER | SERVER_ACCESS_ENUMERATE

SERVER_ALL_ACCESS = &HF0003

---

Duncan Jones