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Defrag API C# wrappers

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For my own amusement, I decided to wrap the NT Defrag APIs in C#. 

It isn't great, but... I'll give it the classic dev guarantee of "it works on my machine".  https://www.thenetworkadministrator.com/top20.htm

The MSDN documentation uses lots of very scary words like "IOCTL" and "DeviceIoControl" and the such.  Hopefully, I've abstracted some of that away...

 

First, you can get a bitmap of the cluster usage on the device...

static public BitArray GetVolumeMap(string DeviceName)

Then you can get a map of a file - virtual clusters and logical clusters

static public Array GetFileMap(string path)

Finally, you can move sections of a file around on a volume...

static public void MoveFile(string deviceName, string path, Int64 VCN, Int64 LCN, Int32 count)

Here's the whole thing, nearly guaranteed to break your file system if used. :-)

//
// a set of simple C# wrappers over the NT Defragmenter APIs
//

//
// Refrences

//
// https://www.sysinternals.com/ntw2k/info/defrag.shtml
//
// msdn how-to
// ms-help://MS.MSDNQTR.2004JUL.1033/fileio/base/defragmenting_files.htm
// https://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/defragmenting_files.asp
//
// FSCTL_GET_VOLUME_BITMAP
// https://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/fsctl_get_volume_bitmap.asp
//
// interesting structures...
// FSCTL_MOVE_FILE
// FSCTL_GET_RETRIEVAL_POINTERS
// RETRIEVAL_POINTERS_BUFFER
// FSCTL_GET_RETRIEVAL_POINTERS
//
// DeviceIoControl
// https://msdn.microsoft.com/library/default.asp?url=/library/en-us/devio/base/deviceiocontrol.asp
//

using System;
using System.Diagnostics;
using System.Collections;
using System.Runtime.InteropServices;

namespace defraglib
{
public class IOWrapper
{

//
// CreateFile constants
//
const uint FILE_SHARE_READ = 0x00000001;
const uint FILE_SHARE_WRITE = 0x00000002;
const uint FILE_SHARE_DELETE = 0x00000004;
const uint OPEN_EXISTING = 3;

const uint GENERIC_READ = (0x80000000);
const uint GENERIC_WRITE = (0x40000000);

const uint FILE_FLAG_NO_BUFFERING = 0x20000000;
const uint FILE_READ_ATTRIBUTES = (0x0080);
const uint FILE_WRITE_ATTRIBUTES = 0x0100;
const uint ERROR_INSUFFICIENT_BUFFER = 122;

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

[DllImport("kernel32.dll", SetLastError = true)]
static extern int CloseHandle(IntPtr hObject);

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool DeviceIoControl(
IntPtr hDevice,
uint dwIoControlCode,
IntPtr lpInBuffer,
uint nInBufferSize,
[Out] IntPtr lpOutBuffer,
uint nOutBufferSize,
ref uint lpBytesReturned,
IntPtr lpOverlapped);

static private IntPtr OpenVolume(string DeviceName)
{
IntPtr hDevice;
hDevice = CreateFile(
@"[\\.\](file://\\.\)" + DeviceName,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_WRITE,
IntPtr.Zero,
OPEN_EXISTING,
0,
IntPtr.Zero);
if ((int)hDevice == -1)
{
throw new Exception(Marshal.GetLastWin32Error().ToString());
}
return hDevice;
}

static private IntPtr OpenFile(string path)
{
IntPtr hFile;
hFile = CreateFile(
path,
FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES,
FILE_SHARE_READ | FILE_SHARE_WRITE,
IntPtr.Zero,
OPEN_EXISTING,
0,
IntPtr.Zero);
if ((int)hFile == -1)
{
throw new Exception(Marshal.GetLastWin32Error().ToString());
}
return hFile;
}

/// <summary>
/// Get cluster usage for a device
/// </summary>
/// <param name="DeviceName">use "c:"</param>
/// <returns>a bitarray for each cluster</returns>
static public BitArray GetVolumeMap(string DeviceName)
{
IntPtr pAlloc = IntPtr.Zero;
IntPtr hDevice = IntPtr.Zero;

try
{
hDevice = OpenVolume(DeviceName);

Int64 i64 = 0;

GCHandle handle = GCHandle.Alloc(i64, GCHandleType.Pinned);
IntPtr p = handle.AddrOfPinnedObject();

// alloc off more than enough for my machine
// 64 megs == 67108864 bytes == 536870912 bits == cluster count
// NTFS 4k clusters == 2147483648 k of storage == 2097152 megs == 2048 gig disk storage
uint q = 1024 * 1024 * 64; // 1024 bytes == 1k * 1024 == 1 meg * 64 == 64 megs

uint size = 0;
pAlloc = Marshal.AllocHGlobal((int)q);
IntPtr pDest = pAlloc;

bool fResult = DeviceIoControl(
hDevice,
FSConstants.FSCTL_GET_VOLUME_BITMAP,
p,
(uint)Marshal.SizeOf(i64),
pDest,
q,
ref size,
IntPtr.Zero);

if (!fResult)
{
throw new Exception(Marshal.GetLastWin32Error().ToString());
}
handle.Free();

/*
object returned was...
typedef struct
{
LARGE_INTEGER StartingLcn;
LARGE_INTEGER BitmapSize;
BYTE Buffer[1];
} VOLUME_BITMAP_BUFFER, *PVOLUME_BITMAP_BUFFER;
*/
Int64 StartingLcn = (Int64)Marshal.PtrToStructure(pDest, typeof(Int64));

Debug.Assert(StartingLcn == 0);

pDest = (IntPtr)((Int64)pDest + 8);
Int64 BitmapSize = (Int64)Marshal.PtrToStructure(pDest, typeof(Int64));

Int32 byteSize = (int)(BitmapSize / 8);
byteSize++; // round up - even with no remainder

IntPtr BitmapBegin = (IntPtr)((Int64)pDest + 8);

byte[] byteArr = new byte[byteSize];

Marshal.Copy(BitmapBegin, byteArr, 0, (Int32)byteSize);

BitArray retVal = new BitArray(byteArr);
retVal.Length = (int)BitmapSize; // truncate to exact cluster count
return retVal;
}
finally
{
CloseHandle(hDevice);
hDevice = IntPtr.Zero;

Marshal.FreeHGlobal(pAlloc);
pAlloc = IntPtr.Zero;
}
}

/// <summary>
/// returns a 2*number of extents array -
/// the vcn and the lcn as pairs
/// </summary>
/// <param name="path">file to get the map for ex: "c:\windows\explorer.exe" </param>
/// <returns>An array of [virtual cluster, physical cluster]</returns>
static public Array GetFileMap(string path)
{
IntPtr hFile = IntPtr.Zero;
IntPtr pAlloc = IntPtr.Zero;

try
{
hFile = OpenFile(path);

Int64 i64 = 0;

GCHandle handle = GCHandle.Alloc(i64, GCHandleType.Pinned);
IntPtr p = handle.AddrOfPinnedObject();

uint q = 1024 * 1024 * 64; // 1024 bytes == 1k * 1024 == 1 meg * 64 == 64 megs

uint size = 0;
pAlloc = Marshal.AllocHGlobal((int)q);
IntPtr pDest = pAlloc;
bool fResult = DeviceIoControl(
hFile,
FSConstants.FSCTL_GET_RETRIEVAL_POINTERS,
p,
(uint)Marshal.SizeOf(i64),
pDest,
q,
ref size,
IntPtr.Zero);

if (!fResult)
{
throw new Exception(Marshal.GetLastWin32Error().ToString());
}

handle.Free();

/*
returned back one of...
typedef struct RETRIEVAL_POINTERS_BUFFER {
DWORD ExtentCount;
LARGE_INTEGER StartingVcn;
struct {
LARGE_INTEGER NextVcn;
LARGE_INTEGER Lcn;
} Extents[1];
} RETRIEVAL_POINTERS_BUFFER, *PRETRIEVAL_POINTERS_BUFFER;
*/

Int32 ExtentCount = (Int32)Marshal.PtrToStructure(pDest, typeof(Int32));

pDest = (IntPtr)((Int64)pDest + 4);

Int64 StartingVcn = (Int64)Marshal.PtrToStructure(pDest, typeof(Int64));

Debug.Assert(StartingVcn == 0);

pDest = (IntPtr)((Int64)pDest + 8);

// now pDest points at an array of pairs of Int64s.

Array retVal = Array.CreateInstance(typeof(Int64), new int[2] { ExtentCount, 2 });

for (int i = 0; i < ExtentCount; i++)
{
for (int j = 0; j < 2; j++)
{
Int64 v = (Int64)Marshal.PtrToStructure(pDest, typeof(Int64));
retVal.SetValue(v, new int[2] { i, j });
pDest = (IntPtr)((Int64)pDest + 8);
}
}

return retVal;
}
finally
{
CloseHandle(hFile);
hFile = IntPtr.Zero;

Marshal.FreeHGlobal(pAlloc);
pAlloc = IntPtr.Zero;
}
}

/// <summary>
/// input structure for use in MoveFile
/// </summary>
private struct MoveFileData
{
public IntPtr hFile;
public Int64 StartingVCN;
public Int64 StartingLCN;
public Int32 ClusterCount;
}

/// <summary>
/// move a virtual cluster for a file to a logical cluster on disk, repeat for count clusters
/// </summary>
/// <param name="deviceName">device to move on"c:"</param>
/// <param name="path">file to muck with "c:\windows\explorer.exe"</param>
/// <param name="VCN">cluster number in file to move</param>
/// <param name="LCN">cluster on disk to move to</param>
/// <param name="count">for how many clusters</param>
static public void MoveFile(string deviceName, string path, Int64 VCN, Int64 LCN, Int32 count)
{
IntPtr hVol = IntPtr.Zero;
IntPtr hFile = IntPtr.Zero;
try
{
hVol = OpenVolume(deviceName);

hFile = OpenFile(path);

MoveFileData mfd = new MoveFileData();
mfd.hFile = hFile;
mfd.StartingVCN = VCN;
mfd.StartingLCN = LCN;
mfd.ClusterCount = count;

GCHandle handle = GCHandle.Alloc(mfd, GCHandleType.Pinned);
IntPtr p = handle.AddrOfPinnedObject();
uint bufSize = (uint)Marshal.SizeOf(mfd);
uint size = 0;

bool fResult = DeviceIoControl(
hVol,
FSConstants.FSCTL_MOVE_FILE,
p,
bufSize,
IntPtr.Zero, // no output data from this FSCTL
0,
ref size,
IntPtr.Zero);

handle.Free();

if (!fResult)
{
throw new Exception(Marshal.GetLastWin32Error().ToString());
}
}
finally
{
CloseHandle(hVol);
CloseHandle(hFile);
}
}
}

/// <summary>
/// constants lifted from winioctl.h from platform sdk
/// </summary>
internal class FSConstants
{
const uint FILE_DEVICE_FILE_SYSTEM = 0x00000009;

const uint METHOD_NEITHER = 3;
const uint METHOD_BUFFERED = 0;

const uint FILE_ANY_ACCESS = 0;
const uint FILE_SPECIAL_ACCESS = FILE_ANY_ACCESS;

public static uint FSCTL_GET_VOLUME_BITMAP = CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 27, METHOD_NEITHER, FILE_ANY_ACCESS);
public static uint FSCTL_GET_RETRIEVAL_POINTERS = CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 28, METHOD_NEITHER, FILE_ANY_ACCESS);
public static uint FSCTL_MOVE_FILE = CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 29, METHOD_BUFFERED, FILE_SPECIAL_ACCESS);

static uint CTL_CODE(uint DeviceType, uint Function, uint Method, uint Access)
{
return ((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method);
}
}

}

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