C#快速找出磁盘内的所有文件

本文只针对NTFS格式化的磁盘文件快速检索，速度不是非常快，是让你震惊。

一般用文件遍历的方法检索一个50G的文件夹需要几十分钟甚至一个小时的时间，而用本方法只需几秒。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using Microsoft.VisualBasic;

public class MFTScanner
{
	private static IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
	private const uint GENERIC_READ = 0x80000000;
	private const int FILE_SHARE_READ = 0x1;
	private const int FILE_SHARE_WRITE = 0x2;
	private const int OPEN_EXISTING = 3;
	private const int FILE_READ_ATTRIBUTES = 0x80;
	private const int FILE_NAME_IINFORMATION = 9;
	private const int FILE_FLAG_BACKUP_SEMANTICS = 0x2000000;
	private const int FILE_OPEN_FOR_BACKUP_INTENT = 0x4000;
	private const int FILE_OPEN_BY_FILE_ID = 0x2000;
	private const int FILE_OPEN = 0x1;
	private const int OBJ_CASE_INSENSITIVE = 0x40;
	private const int FSCTL_ENUM_USN_DATA = 0x900b3;

	[StructLayout(LayoutKind.Sequential)]
	private struct MFT_ENUM_DATA
	{
		public long StartFileReferenceNumber;
		public long LowUsn;
		public long HighUsn;
	}

	[StructLayout(LayoutKind.Sequential)]
	private struct USN_RECORD
	{
		public int RecordLength;
		public short MajorVersion;
		public short MinorVersion;
		public long FileReferenceNumber;
		public long ParentFileReferenceNumber;
		public long Usn;
		public long TimeStamp;
		public int Reason;
		public int SourceInfo;
		public int SecurityId;
		public FileAttribute FileAttributes;
		public short FileNameLength;
		public short FileNameOffset;
	}

	[StructLayout(LayoutKind.Sequential)]
	private struct IO_STATUS_BLOCK
	{
		public int Status;
		public int Information;
	}

	[StructLayout(LayoutKind.Sequential)]
	private struct UNICODE_STRING
	{
		public short Length;
		public short MaximumLength;
		public IntPtr Buffer;
	}

	[StructLayout(LayoutKind.Sequential)]
	private struct OBJECT_ATTRIBUTES
	{
		public int Length;
		public IntPtr RootDirectory;
		public IntPtr ObjectName;
		public int Attributes;
		public int SecurityDescriptor;
		public int SecurityQualityOfService;
	}

	//// MFT_ENUM_DATA
	[DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
	private static extern bool DeviceIoControl(IntPtr hDevice, int dwIoControlCode, ref MFT_ENUM_DATA lpInBuffer, int nInBufferSize, IntPtr lpOutBuffer, int nOutBufferSize, ref int lpBytesReturned, IntPtr lpOverlapped);

	[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
	private static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess, int dwShareMode, IntPtr lpSecurityAttributes, int dwCreationDisposition, int dwFlagsAndAttributes, IntPtr hTemplateFile);

	[DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
	private static extern Int32 CloseHandle(IntPtr lpObject);

	[DllImport("ntdll.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
	private static extern int NtCreateFile(ref IntPtr FileHandle, int DesiredAccess, ref OBJECT_ATTRIBUTES ObjectAttributes, ref IO_STATUS_BLOCK IoStatusBlock, int AllocationSize, int FileAttribs, int SharedAccess, int CreationDisposition, int CreateOptions, int EaBuffer,
	int EaLength);

	[DllImport("ntdll.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
	private static extern int NtQueryInformationFile(IntPtr FileHandle, ref IO_STATUS_BLOCK IoStatusBlock, IntPtr FileInformation, int Length, int FileInformationClass);

	private IntPtr m_hCJ;
	private IntPtr m_Buffer;
	private int m_BufferSize;

	private string m_DriveLetter;

	private class FSNode
	{
		public long FRN;
		public long ParentFRN;
		public string FileName;

		public bool IsFile;
		public FSNode(long lFRN, long lParentFSN, string sFileName, bool bIsFile)
		{
			FRN = lFRN;
			ParentFRN = lParentFSN;
			FileName = sFileName;
			IsFile = bIsFile;
		}

	}

	private IntPtr OpenVolume(string szDriveLetter)
	{

		IntPtr hCJ = default(IntPtr);
		//// volume handle

		m_DriveLetter = szDriveLetter;

		hCJ = CreateFile("\\\\.\\" + szDriveLetter, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);

		return hCJ;

	}

	private void Cleanup()
	{
		if (m_hCJ != IntPtr.Zero)
		{
			// Close the volume handle.
			CloseHandle(m_hCJ);
			m_hCJ = INVALID_HANDLE_VALUE;
		}

		if (m_Buffer != IntPtr.Zero)
		{
			// Free the allocated memory
			Marshal.FreeHGlobal(m_Buffer);
			m_Buffer = IntPtr.Zero;
		}

	}

	public IEnumerable<String> EnumerateFiles(string szDriveLetter)
	{
		try
		{
			var usnRecord = default(USN_RECORD);
			var mft = default(MFT_ENUM_DATA);
			var dwRetBytes = 0;
			var cb = 0;
			var dicFRNLookup = new Dictionary<long, FSNode>();
			var bIsFile = false;

			// This shouldn't be called more than once.
			if (m_Buffer.ToInt32() != 0)
			{
				throw new Exception("invalid buffer");
			}

			// Assign buffer size
			m_BufferSize = 65536;
			//64KB

			// Allocate a buffer to use for reading records.
			m_Buffer = Marshal.AllocHGlobal(m_BufferSize);

			// correct path
			szDriveLetter = szDriveLetter.TrimEnd('\\');

			// Open the volume handle
			m_hCJ = OpenVolume(szDriveLetter);

			// Check if the volume handle is valid.
			if (m_hCJ == INVALID_HANDLE_VALUE)
			{
				throw new Exception("Couldn't open handle to the volume.");
			}

			mft.StartFileReferenceNumber = 0;
			mft.LowUsn = 0;
			mft.HighUsn = long.MaxValue;

			do
			{
				if (DeviceIoControl(m_hCJ, FSCTL_ENUM_USN_DATA, ref mft, Marshal.SizeOf(mft), m_Buffer, m_BufferSize, ref dwRetBytes, IntPtr.Zero))
				{
					cb = dwRetBytes;
					// Pointer to the first record
					IntPtr pUsnRecord = new IntPtr(m_Buffer.ToInt32() + 8);

					while ((dwRetBytes > 8))
					{
						// Copy pointer to USN_RECORD structure.
						usnRecord = (USN_RECORD)Marshal.PtrToStructure(pUsnRecord, usnRecord.GetType());

						// The filename within the USN_RECORD.
						string FileName = Marshal.PtrToStringUni(new IntPtr(pUsnRecord.ToInt32() + usnRecord.FileNameOffset), usnRecord.FileNameLength / 2);

						bIsFile = !usnRecord.FileAttributes.HasFlag(FileAttribute.Directory);
						dicFRNLookup.Add(usnRecord.FileReferenceNumber, new FSNode(usnRecord.FileReferenceNumber, usnRecord.ParentFileReferenceNumber, FileName, bIsFile));

						// Pointer to the next record in the buffer.
						pUsnRecord = new IntPtr(pUsnRecord.ToInt32() + usnRecord.RecordLength);

						dwRetBytes -= usnRecord.RecordLength;
					}

					// The first 8 bytes is always the start of the next USN.
					mft.StartFileReferenceNumber = Marshal.ReadInt64(m_Buffer, 0);

				}
				else
				{
					break; // TODO: might not be correct. Was : Exit Do

				}

			} while (!(cb <= 8));

			// Resolve all paths for Files
			foreach (FSNode oFSNode in dicFRNLookup.Values.Where(o => o.IsFile))
			{
				string sFullPath = oFSNode.FileName;
				FSNode oParentFSNode = oFSNode;

				while (dicFRNLookup.TryGetValue(oParentFSNode.ParentFRN, out oParentFSNode))
				{
					sFullPath = string.Concat(oParentFSNode.FileName, "\\", sFullPath);
				}
				sFullPath = string.Concat(szDriveLetter, "\\", sFullPath);

				yield return sFullPath;
			}
		}
		finally
		{
			//// cleanup
			Cleanup();
		}
	}
}

调用方法：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Diagnostics;

namespace ConsoleApplication28
{
	class Program
	{
		static void Main(string[] args)
		{
			var sw = Stopwatch.StartNew();
			var files = EnumerateFiles("f:").ToArray();
			var elapsed = sw.ElapsedMilliseconds.ToString();
			Console.WriteLine(string.Format("Found {0} files, elapsed {1} ms", files.Length, elapsed));
		}
	}
}

方法只能传磁盘名