/Visual Studio 2008/CSListFilesInDirectory/NativeMethods.cs

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

* Module Name:  NativeMethods.cs

* Project:      CSListFilesInDirectory

* Copyright (c) Microsoft Corporation.

* 

* The CSListFilesInDirectory project demonstrates how to implement an IEnumerable<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:

* * 7/7/2009 8:00 PM Jie Wang Created

\******************************************************************************************/



#region Using directives

using System;

using System.Runtime.InteropServices;

using System.Runtime.ConstrainedExecution;

using System.Security.Permissions;

using Microsoft.Win32.SafeHandles;

#endregion





[Serializable, StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto), 

BestFitMapping(false)]

internal class WIN32_FIND_DATA

{

    internal int dwFileAttributes;

    internal int ftCreationTime_dwLowDateTime;

    internal int ftCreationTime_dwHighDateTime;

    internal int ftLastAccessTime_dwLowDateTime;

    internal int ftLastAccessTime_dwHighDateTime;

    internal int ftLastWriteTime_dwLowDateTime;

    internal int ftLastWriteTime_dwHighDateTime;

    internal int nFileSizeHigh;

    internal int nFileSizeLow;

    internal int dwReserved0;

    internal int dwReserved1;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]

    internal string cFileName;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]

    internal string cAlternateFileName;

}



/// <summary>

/// Win32 Native P/Invoke

/// </summary>

internal static class NativeMethods

{

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]

    internal static extern SafeFindHandle FindFirstFile(

        string fileName, [In, Out] WIN32_FIND_DATA data);



    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]

    internal static extern bool FindNextFile(

        SafeFindHandle hndFindFile, 

        [In, Out, MarshalAs(UnmanagedType.LPStruct)] 

        WIN32_FIND_DATA lpFindFileData);



    [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), DllImport("kernel32.dll")]

    internal static extern bool FindClose(IntPtr handle);



    internal const int ERROR_SUCCESS = 0;

    internal const int ERROR_NO_MORE_FILES = 18;

    internal const int ERROR_FILE_NOT_FOUND = 2;

    internal const int FILE_ATTRIBUTE_DIRECTORY = 0x00000010;

}



/// <summary>

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

/// </summary>

internal sealed class SafeFindHandle : SafeHandleZeroOrMinusOneIsInvalid

{

    [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]

    internal SafeFindHandle()

        : base(true)

    {

    }



    protected override bool ReleaseHandle()

    {

        // Close the search handle.

        return NativeMethods.FindClose(base.handle);

    }

}