/Visual Studio 2008/VBListFilesInDirectory/NativeMethods.vb

'/************************************* Module Header **************************************\

'* Module Name:  NativeMethods.vb

'* Project:      VBListFilesInDirectory

'* Copyright (c) Microsoft Corporation.

'* 

'* The VBListFilesInDirectory project demonstrates how to implement an IEnumerable(Of String)

'* that utilizes the Win32 File Management functions to enable application to get files and

'* sub-directories in a specified directory one item a time.

'* 

'* This source is subject to the Microsoft Public License.

'* See http://www.microsoft.com/opensource/licenses.mspx#Ms-PL.

'* All other rights reserved.

'* 

'* History:

'* * 30/8/2009 1:00 PM Jie Wang Created

'\******************************************************************************************/





#Region "Using directives"

Imports System

Imports System.Runtime.InteropServices

Imports System.Runtime.ConstrainedExecution

Imports System.Security.Permissions

Imports Microsoft.Win32.SafeHandles

#End Region





<Serializable(), StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto), _

BestFitMapping(False)> _

Friend Class WIN32_FIND_DATA

    Friend dwFileAttributes As Integer

    Friend ftCreationTime_dwLowDateTime As Integer

    Friend ftCreationTime_dwHighDateTime As Integer

    Friend ftLastAccessTime_dwLowDateTime As Integer

    Friend ftLastAccessTime_dwHighDateTime As Integer

    Friend ftLastWriteTime_dwLowDateTime As Integer

    Friend ftLastWriteTime_dwHighDateTime As Integer

    Friend nFileSizeHigh As Integer

    Friend nFileSizeLow As Integer

    Friend dwReserved0 As Integer

    Friend dwReserved1 As Integer

    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=260)> _

    Friend cFileName As String

    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=14)> _

    Friend cAlternateFileName As String

End Class





''' <summary>

''' Win32 Native P/Invoke

''' </summary>

Friend Module NativeMethods

    <DllImport("kernel32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _

    Friend Function FindFirstFile( _

        ByVal fileName As String, _

        <[In](), Out()> ByVal data As WIN32_FIND_DATA) As SafeFindHandle

    End Function



    <DllImport("kernel32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _

    Friend Function FindNextFile( _

        ByVal hndFindFile As SafeFindHandle, _

        <[In](), Out(), MarshalAs(UnmanagedType.LPStruct)> ByVal _

         lpFindFileData As WIN32_FIND_DATA) As Boolean

    End Function



    <ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), DllImport("kernel32.dll")> _

    Friend Function FindClose(ByVal handle As IntPtr) As Boolean

    End Function



    Friend Const ERROR_SUCCESS As Integer = 0

    Friend Const ERROR_NO_MORE_FILES As Integer = 18

    Friend Const ERROR_FILE_NOT_FOUND As Integer = 2

    Friend Const FILE_ATTRIBUTE_DIRECTORY As Integer = &H10

End Module





''' <summary>

''' Safe handle for using with the Find File APIs.

''' </summary>

Friend NotInheritable Class SafeFindHandle

    Inherits SafeHandleZeroOrMinusOneIsInvalid



    <SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode:=True)> _

    Friend Sub New()

        MyBase.New(True)

    End Sub



    Protected Overrides Function ReleaseHandle() As Boolean

        ' Close the search handle.

        Return NativeMethods.FindClose(MyBase.handle)

    End Function

End Class