source: branches/eraser6/Util/VolumeInfo.cs @ 489

/* 
 * $Id$
 * Copyright 2008 The Eraser Project
 * Original Author: Joel Low <lowjoel@users.sourceforge.net>
 * Modified By:
 * 
 * This file is part of Eraser.
 * 
 * Eraser is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * Eraser is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 * 
 * A copy of the GNU General Public License can be found at
 * <http://www.gnu.org/licenses/>.
 */

using System;
using System.Collections.Generic;
using System.Text;

using System.Runtime.InteropServices;
using System.ComponentModel;
using System.IO;
using Microsoft.Win32.SafeHandles;

namespace Eraser.Util
{
    public class VolumeInfo
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="volumeID">The ID of the volume, in the form "\\?\Volume{GUID}\"</param>
        public VolumeInfo(string volumeID)
        {
            //Set the volume Id
            this.volumeID = volumeID;

            //Get the paths of the said volume
            IntPtr pathNamesBuffer = IntPtr.Zero;
            string pathNames = string.Empty;
            try
            {
                uint currentBufferSize = MaxPath;
                uint returnLength = 0;
                pathNamesBuffer = Marshal.AllocHGlobal((int)(currentBufferSize * sizeof(char)));
                while (!GetVolumePathNamesForVolumeName(volumeID, pathNamesBuffer, currentBufferSize,
                    out returnLength))
                {
                    if (Marshal.GetLastWin32Error() == 234/*ERROR_MORE_DATA*/)
                    {
                        currentBufferSize *= 2;
                        pathNamesBuffer = Marshal.AllocHGlobal((int)(currentBufferSize * sizeof(char)));
                    }
                    else
                        throw new Win32Exception(Marshal.GetLastWin32Error(),
                            "Eraser.Util.Volume.Volume");
                }

                pathNames = Marshal.PtrToStringUni(pathNamesBuffer, (int)returnLength);
            }
            finally
            {
                if (pathNamesBuffer != IntPtr.Zero)
                    Marshal.FreeHGlobal(pathNamesBuffer);
            }

            //OK, the marshalling is complete. Convert the pathNames string into a list
            //of strings containing all of the volumes mountpoints; because the
            //GetVolumePathNamesForVolumeName function returns a convoluted structure
            //containing the path names.
            for (int lastIndex = 0, i = 0; i != pathNames.Length; ++i)
            {
                if (pathNames[i] == '\0')
                {
                    mountPoints.Add(pathNames.Substring(lastIndex, i - lastIndex));

                    lastIndex = i + 1;
                    if (pathNames[lastIndex] == '\0')
                        break;
                }
            }

            //Fill up the remaining members of the structure: file system, label, etc.
            StringBuilder volumeName = new StringBuilder(MaxPath * sizeof(char)),
                   fileSystemName = new StringBuilder(MaxPath * sizeof(char));
            uint serialNumber, maxComponentLength, filesystemFlags;
            if (!GetVolumeInformation(volumeID, volumeName, MaxPath, out serialNumber,
                out maxComponentLength, out filesystemFlags, fileSystemName, MaxPath))
            {
                if (Marshal.GetLastWin32Error() != 21 /*ERROR_NOT_READY*/)
                    throw new Win32Exception(Marshal.GetLastWin32Error(), "Eraser.Util.Volume.Volume");
            }
            else
                isReady = true;

            volumeLabel = volumeName.ToString();
            volumeFormat = fileSystemName.ToString();
        }

        /// <summary>
        /// Lists all the volumes in the system.
        /// </summary>
        /// <returns>Returns a list of volumes representing all volumes present in
        /// the system.</returns>
        public static List<VolumeInfo> GetVolumes()
        {
            List<VolumeInfo> result = new List<VolumeInfo>();
            StringBuilder nextVolume = new StringBuilder(LongPath * sizeof(char));
            SafeHandle handle = FindFirstVolume(nextVolume, LongPath);
            if (handle.IsInvalid)
                return result;

            //Iterate over the volume mountpoints
            do
                result.Add(new VolumeInfo(nextVolume.ToString()));
            while (FindNextVolume(handle, nextVolume, LongPath));

            //Close the handle
            if (Marshal.GetLastWin32Error() == 18 /*ERROR_NO_MORE_FILES*/)
                FindVolumeClose(handle);
            
            return result;
        }

        /// <summary>
        /// Creates a Volume object from its mountpoint.
        /// </summary>
        /// <param name="mountpoint">The path to the mountpoint.</param>
        /// <returns>The volume object if such a volume exists, or an exception
        /// is thrown.</returns>
        public static VolumeInfo FromMountpoint(string mountpoint)
        {
            DirectoryInfo mountpointDir = new DirectoryInfo(mountpoint);
            StringBuilder volumeID = new StringBuilder(50 * sizeof(char));

            do
            {
                string currentDir = mountpointDir.FullName;
                if (currentDir.Length > 0 && currentDir[currentDir.Length - 1] != '\\')
                    currentDir += '\\';
                if (GetVolumeNameForVolumeMountPoint(currentDir, volumeID, 50))
                    return new VolumeInfo(volumeID.ToString());
                else
                    switch (Marshal.GetLastWin32Error())
                    {
                        case 1:
                        case 4390:
                            break;
                        default:
                            throw new Win32Exception(Marshal.GetLastWin32Error());
                    }
                mountpointDir = mountpointDir.Parent;
            }
            while (mountpointDir != null);

            throw new Win32Exception(4390 /*ERROR_NOT_A_REPARSE_POINT*/);
        }

        /// <summary>
        /// Returns the volume identifier as would be returned from FindFirstVolume.
        /// </summary>
        public string VolumeID
        {
            get { return volumeID; }
        }
        private string volumeID;

        /// <summary>
        /// Gets or sets the volume label of a drive.
        /// </summary>
        public string VolumeLabel
        {
            get { return VolumeLabel; }
            set { throw new NotImplementedException();  }
        }
        private string volumeLabel;

        /// <summary>
        /// Gets the name of the file system, such as NTFS or FAT32.
        /// </summary>
        public string VolumeFormat
        {
            get
            {
                return volumeFormat;
            }
        }
        private string volumeFormat;

        /// <summary>
        /// Gets the drive type; returns one of the System.IO.DriveType values.
        /// </summary>
        public DriveType VolumeType
        {
            get
            {
                return (DriveType)GetDriveType(VolumeID);
            }
        }

        /// <summary>
        /// Determines the cluster size of the current volume.
        /// </summary>
        public int ClusterSize
        {
            get
            {
                uint clusterSize, sectorSize, freeClusters, totalClusters;
                if (GetDiskFreeSpace(volumeID, out clusterSize, out sectorSize,
                    out freeClusters, out totalClusters))
                    return (int)(clusterSize * sectorSize);

                throw new Win32Exception(Marshal.GetLastWin32Error(),
                    "Eraser.Util.Drive.GetClusterSize");
            }
        }

        /// <summary>
        /// Checks if the current user has disk quotas on the current volume.
        /// </summary>
        public bool HasQuota
        {
            get
            {
                ulong freeBytesAvailable, totalNumberOfBytes, totalNumberOfFreeBytes;
                if (GetDiskFreeSpaceEx(volumeID, out freeBytesAvailable, out totalNumberOfBytes,
                    out totalNumberOfFreeBytes))
                    return totalNumberOfFreeBytes != freeBytesAvailable;
                else if (Marshal.GetLastWin32Error() == 21 /*ERROR_NOT_READY*/)
                    //For the lack of more appropriate responses.
                    return false;

                throw new Win32Exception(Marshal.GetLastWin32Error(),
                    "Eraser.Util.Drive.HasQuota");
            }
        }

        /// <summary>
        /// Gets a value indicating whether a drive is ready.
        /// </summary>
        public bool IsReady
        {
            get { return isReady; }
        }
        private bool isReady = false;

        /// <summary>
        /// Gets the total amount of free space available on a drive.
        /// </summary>
        public long TotalFreeSpace
        {
            get
            {
                ulong result, dummy;
                if (GetDiskFreeSpaceEx(volumeID, out dummy, out dummy, out result))
                    return (long)result;

                throw new Win32Exception(Marshal.GetLastWin32Error(),
                    "Eraser.Util.Drive.TotalFreeSpace");
            }
        }
        
        /// <summary>
        /// Gets the total size of storage space on a drive.
        /// </summary>
        public long TotalSize
        {
            get
            {
                UInt64 result, dummy;
                if (GetDiskFreeSpaceEx(volumeID, out dummy, out result, out dummy))
                    return (long)result;

                throw new Win32Exception(Marshal.GetLastWin32Error(),
                    "Eraser.Util.Drive.TotalSize");
            }
        }

        /// <summary>
        /// Indicates the amount of available free space on a drive.
        /// </summary>
        public long AvailableFreeSpace
        {
            get
            {
                UInt64 result, dummy;
                if (GetDiskFreeSpaceEx(volumeID, out result, out dummy, out dummy))
                    return (long)result;

                throw new Win32Exception(Marshal.GetLastWin32Error(),
                    "Eraser.Util.Drive.AvailableFreeSpace");
            }
        }

        /// <summary>
        /// Retrieves all mountpoints in the current volume, if the current volume
        /// contains volume mountpoints.
        /// </summary>
        public List<VolumeInfo> MountedVolumes
        {
            get
            {
                List<VolumeInfo> result = new List<VolumeInfo>();
                StringBuilder nextMountpoint = new StringBuilder(LongPath * sizeof(char));

                SafeHandle handle = FindFirstVolumeMountPoint(VolumeID,
                    nextMountpoint, LongPath);
                if (handle.IsInvalid)
                    return result;

                //Iterate over the volume mountpoints
                while (FindNextVolumeMountPoint(handle, nextMountpoint, LongPath))
                    result.Add(new VolumeInfo(nextMountpoint.ToString()));

                //Close the handle
                if (Marshal.GetLastWin32Error() == 18 /*ERROR_NO_MORE_FILES*/)
                    FindVolumeMountPointClose(handle);

                return result;
            }
        }

        /// <summary>
        /// The various mountpoints to the root of the volume. This list contains
        /// paths which may be a drive or a mountpoint. Every string includes the
        /// trailing backslash.
        /// </summary>
        public List<string> MountPoints
        {
            get { return mountPoints; }
            set { mountPoints = value; }
        }
        private List<string> mountPoints = new List<string>();

        /// <summary>
        /// Gets whether the current volume is mounted at any place.
        /// </summary>
        public bool IsMounted
        {
            get { return mountPoints.Count != 0; }
        }

        #region Windows API Functions
        internal const int MaxPath = 260;
        internal const int LongPath = 32768;

        /// <summary>
        /// Retrieves information about the file system and volume associated with
        /// the specified root directory.
        /// 
        /// To specify a handle when retrieving this information, use the
        /// GetVolumeInformationByHandleW function.
        /// 
        /// To retrieve the current compression state of a file or directory, use
        /// FSCTL_GET_COMPRESSION.
        /// </summary>
        /// <param name="lpRootPathName">    A pointer to a string that contains
        /// the root directory of the volume to be described.
        /// 
        /// If this parameter is NULL, the root of the current directory is used.
        /// A trailing backslash is required. For example, you specify
        /// \\MyServer\MyShare as "\\MyServer\MyShare\", or the C drive as "C:\".</param>
        /// <param name="lpVolumeNameBuffer">A pointer to a buffer that receives
        /// the name of a specified volume. The maximum buffer size is MAX_PATH+1.</param>
        /// <param name="nVolumeNameSize">The length of a volume name buffer, in
        /// TCHARs. The maximum buffer size is MAX_PATH+1.
        /// 
        /// This parameter is ignored if the volume name buffer is not supplied.</param>
        /// <param name="lpVolumeSerialNumber">A pointer to a variable that receives
        /// the volume serial number.
        /// 
        /// This parameter can be NULL if the serial number is not required.
        /// 
        /// This function returns the volume serial number that the operating system
        /// assigns when a hard disk is formatted. To programmatically obtain the
        /// hard disk's serial number that the manufacturer assigns, use the
        /// Windows Management Instrumentation (WMI) Win32_PhysicalMedia property
        /// SerialNumber.</param>
        /// <param name="lpMaximumComponentLength">A pointer to a variable that
        /// receives the maximum length, in TCHARs, of a file name component that
        /// a specified file system supports.
        /// 
        /// A file name component is the portion of a file name between backslashes.
        /// 
        /// The value that is stored in the variable that *lpMaximumComponentLength
        /// points to is used to indicate that a specified file system supports
        /// long names. For example, for a FAT file system that supports long names,
        /// the function stores the value 255, rather than the previous 8.3 indicator.
        /// Long names can also be supported on systems that use the NTFS file system.</param>
        /// <param name="lpFileSystemFlags">A pointer to a variable that receives
        /// flags associated with the specified file system.
        /// 
        /// This parameter can be one or more of the FS_FILE* flags. However,
        /// FS_FILE_COMPRESSION and FS_VOL_IS_COMPRESSED are mutually exclusive.</param>
        /// <param name="lpFileSystemNameBuffer">A pointer to a buffer that receives
        /// the name of the file system, for example, the FAT file system or the
        /// NTFS file system. The maximum buffer size is MAX_PATH+1.</param>
        /// <param name="nFileSystemNameSize">The length of the file system name
        /// buffer, in TCHARs. The maximum buffer size is MAX_PATH+1.
        /// 
        /// This parameter is ignored if the file system name buffer is not supplied.</param>
        /// <returns>If all the requested information is retrieved, the return value
        /// is nonzero.
        /// 
        /// 
        /// If not all the requested information is retrieved, the return value is
        /// zero (0). To get extended error information, call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool GetVolumeInformation(
            string lpRootPathName,
            StringBuilder lpVolumeNameBuffer,
            uint nVolumeNameSize,
            out uint lpVolumeSerialNumber,
            out uint lpMaximumComponentLength,
            out uint lpFileSystemFlags,
            StringBuilder lpFileSystemNameBuffer,
            uint nFileSystemNameSize);

        /// <summary>
        /// Retrieves information about the specified disk, including the amount
        /// of free space on the disk.
        /// 
        /// The GetDiskFreeSpace function cannot report volume sizes that are
        /// greater than 2 gigabytes (GB). To ensure that your application works
        /// with large capacity hard drives, use the GetDiskFreeSpaceEx function.
        /// </summary>
        /// <param name="lpRootPathName">The root directory of the disk for which
        /// information is to be returned. If this parameter is NULL, the function
        /// uses the root of the current disk. If this parameter is a UNC name,
        /// it must include a trailing backslash (for example, \\MyServer\MyShare\).
        /// Furthermore, a drive specification must have a trailing backslash
        /// (for example, C:\). The calling application must have FILE_LIST_DIRECTORY
        /// access rights for this directory.</param>
        /// <param name="lpSectorsPerCluster">A pointer to a variable that receives
        /// the number of sectors per cluster.</param>
        /// <param name="lpBytesPerSector">A pointer to a variable that receives
        /// the number of bytes per sector.</param>
        /// <param name="lpNumberOfFreeClusters">A pointer to a variable that
        /// receives the total number of free clusters on the disk that are
        /// available to the user who is associated with the calling thread.
        /// 
        /// If per-user disk quotas are in use, this value may be less than the 
        /// total number of free clusters on the disk.</param>
        /// <param name="lpTotalNumberOfClusters">A pointer to a variable that
        /// receives the total number of clusters on the disk that are available
        /// to the user who is associated with the calling thread.
        /// 
        /// If per-user disk quotas are in use, this value may be less than the
        /// total number of clusters on the disk.</param>
        /// <returns>If the function succeeds, the return value is true. To get
        /// extended error information, call Marshal.GetLastWin32Error().</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool GetDiskFreeSpace(
            string lpRootPathName, out UInt32 lpSectorsPerCluster, out UInt32 lpBytesPerSector,
            out UInt32 lpNumberOfFreeClusters, out UInt32 lpTotalNumberOfClusters);

        /// <summary>
        /// Retrieves information about the amount of space that is available on
        /// a disk volume, which is the total amount of space, the total amount
        /// of free space, and the total amount of free space available to the
        /// user that is associated with the calling thread.
        /// </summary>
        /// <param name="lpDirectoryName">A directory on the disk.
        /// 
        /// If this parameter is NULL, the function uses the root of the current
        /// disk.
        /// 
        /// If this parameter is a UNC name, it must include a trailing backslash,
        /// for example, "\\MyServer\MyShare\".
        /// 
        /// This parameter does not have to specify the root directory on a disk.
        /// The function accepts any directory on a disk.
        /// 
        /// The calling application must have FILE_LIST_DIRECTORY access rights
        /// for this directory.</param>
        /// <param name="lpFreeBytesAvailable">A pointer to a variable that receives
        /// the total number of free bytes on a disk that are available to the
        /// user who is associated with the calling thread.
        /// 
        /// This parameter can be NULL.
        /// 
        /// If per-user quotas are being used, this value may be less than the
        /// total number of free bytes on a disk.</param>
        /// <param name="lpTotalNumberOfBytes">A pointer to a variable that receives
        /// the total number of bytes on a disk that are available to the user who
        /// is associated with the calling thread.
        /// 
        /// This parameter can be NULL.
        /// 
        /// If per-user quotas are being used, this value may be less than the
        /// total number of bytes on a disk.
        /// 
        /// To determine the total number of bytes on a disk or volume, use
        /// IOCTL_DISK_GET_LENGTH_INFO.</param>
        /// <param name="lpTotalNumberOfFreeBytes">A pointer to a variable that
        /// receives the total number of free bytes on a disk.
        /// 
        /// This parameter can be NULL.</param>
        /// <returns>If the function succeeds, the return value is nonzero.
        /// 
        /// If the function fails, the return value is zero (0). To get extended
        /// error information, call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool GetDiskFreeSpaceEx(
            string lpDirectoryName,
            out UInt64 lpFreeBytesAvailable,
            out UInt64 lpTotalNumberOfBytes,
            out UInt64 lpTotalNumberOfFreeBytes);

        /// <summary>
        /// Retrieves the name of a volume on a computer. FindFirstVolume is used
        /// to begin scanning the volumes of a computer.
        /// </summary>
        /// <param name="lpszVolumeName">A pointer to a buffer that receives a
        /// null-terminated string that specifies the unique volume name of the
        /// first volume found.</param>
        /// <param name="cchBufferLength">The length of the buffer to receive the
        /// name, in TCHARs.</param>
        /// <returns>If the function succeeds, the return value is a search handle
        /// used in a subsequent call to the FindNextVolume and FindVolumeClose
        /// functions.
        /// 
        /// If the function fails to find any volumes, the return value is the
        /// INVALID_HANDLE_VALUE error code. To get extended error information,
        /// call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        internal static extern SafeFileHandle FindFirstVolume(StringBuilder lpszVolumeName,
            uint cchBufferLength);

        /// <summary>
        /// Continues a volume search started by a call to the FindFirstVolume
        /// function. FindNextVolume finds one volume per call.
        /// </summary>
        /// <param name="hFindVolume">The volume search handle returned by a previous
        /// call to the FindFirstVolume function.</param>
        /// <param name="lpszVolumeName">A pointer to a string that receives the
        /// unique volume name found.</param>
        /// <param name="cchBufferLength">The length of the buffer that receives
        /// the name, in TCHARs.</param>
        /// <returns>If the function succeeds, the return value is nonzero.
        /// 
        /// If the function fails, the return value is zero. To get extended error
        /// information, call GetLastError. If no matching files can be found, the
        /// GetLastError function returns the ERROR_NO_MORE_FILES error code. In
        /// that case, close the search with the FindVolumeClose function.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool FindNextVolume(SafeHandle hFindVolume,
            StringBuilder lpszVolumeName, uint cchBufferLength);

        /// <summary>
        /// Closes the specified volume search handle. The FindFirstVolume and
        /// FindNextVolume functions use this search handle to locate volumes.
        /// </summary>
        /// <param name="hFindVolume">The volume search handle to be closed. This
        /// handle must have been previously opened by the FindFirstVolume function.</param>
        /// <returns>If the function succeeds, the return value is nonzero.
        /// 
        /// If the function fails, the return value is zero. To get extended error
        /// information, call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool FindVolumeClose(SafeHandle hFindVolume);

        /// <summary>
        /// Retrieves the name of a volume mount point on the specified volume.
        /// FindFirstVolumeMountPoint is used to begin scanning the volume mount
        /// points on a volume.
        /// </summary>
        /// <param name="lpszRootPathName">The unique volume name of the volume
        /// to scan for volume mount points. A trailing backslash is required.</param>
        /// <param name="lpszVolumeMountPoint">A pointer to a buffer that receives
        /// the name of the first volume mount point found.</param>
        /// <param name="cchBufferLength">The length of the buffer that receives
        /// the volume mount point name, in TCHARs.</param>
        /// <returns>If the function succeeds, the return value is a search handle
        /// used in a subsequent call to the FindNextVolumeMountPoint and
        /// FindVolumeMountPointClose functions.
        /// 
        /// If the function fails to find a volume mount point on the volume, the
        /// return value is the INVALID_HANDLE_VALUE error code. To get extended
        /// error information, call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        internal static extern SafeFileHandle FindFirstVolumeMountPoint(
            string lpszRootPathName, StringBuilder lpszVolumeMountPoint,
            uint cchBufferLength);

        /// <summary>
        /// Continues a volume mount point search started by a call to the
        /// FindFirstVolumeMountPoint function. FindNextVolumeMountPoint finds one
        /// volume mount point per call.
        /// </summary>
        /// <param name="hFindVolumeMountPoint">A mount-point search handle returned
        /// by a previous call to the FindFirstVolumeMountPoint function.</param>
        /// <param name="lpszVolumeMountPoint">A pointer to a buffer that receives
        /// the name of the volume mount point found.</param>
        /// <param name="cchBufferLength">The length of the buffer that receives
        /// the names, in TCHARs.</param>
        /// <returns>If the function succeeds, the return value is nonzero.
        /// 
        /// If the function fails, the return value is zero. To get extended error
        /// information, call GetLastError. If no matching files can be found, the
        /// GetLastError function returns the ERROR_NO_MORE_FILES error code. In
        /// that case, close the search with the FindVolumeMountPointClose function.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool FindNextVolumeMountPoint(
            SafeHandle hFindVolumeMountPoint, StringBuilder lpszVolumeMountPoint,
            uint cchBufferLength);

        /// <summary>
        /// Closes the specified mount-point search handle. The FindFirstVolumeMountPoint
        /// and FindNextVolumeMountPoint  functions use this search handle to locate
        /// volume mount points on a specified volume.
        /// </summary>
        /// <param name="hFindVolumeMountPoint">The mount-point search handle to
        /// be closed. This handle must have been previously opened by the
        /// FindFirstVolumeMountPoint function.</param>
        /// <returns>If the function succeeds, the return value is nonzero.
        ///
        /// If the function fails, the return value is zero. To get extended error
        /// information, call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool FindVolumeMountPointClose(SafeHandle hFindVolumeMountPoint);

        /// <summary>
        /// Retrieves the unique volume name for the specified volume mount point or root directory.
        /// </summary>
        /// <param name="lpszVolumeMountPoint">The path of a volume mount point (with a trailing
        /// backslash, "\") or a drive letter indicating a root directory (in the
        /// form "D:\").</param>
        /// <param name="lpszVolumeName">A pointer to a string that receives the
        /// volume name. This name is a unique volume name of the form
        /// "\\?\Volume{GUID}\" where GUID is the GUID that identifies the volume.</param>
        /// <param name="cchBufferLength">The length of the output buffer, in TCHARs.
        /// A reasonable size for the buffer to accommodate the largest possible
        /// volume name is 50 characters.</param>
        /// <returns>If the function succeeds, the return value is nonzero.
        /// 
        /// If the function fails, the return value is zero. To get extended
        /// error information, call GetLastError.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        [return: MarshalAs(UnmanagedType.Bool)]
        internal static extern bool GetVolumeNameForVolumeMountPoint(
            string lpszVolumeMountPoint, StringBuilder lpszVolumeName,
            uint cchBufferLength);

        /// <summary>
        /// Retrieves a list of path names for the specified volume name.
        /// </summary>
        /// <param name="lpszVolumeName">The volume name.</param>
        /// <param name="lpszVolumePathNames">A pointer to a buffer that receives
        /// the list of volume path names. The list is an array of null-terminated
        /// strings terminated by an additional NULL character. If the buffer is
        /// not large enough to hold the complete list, the buffer holds as much
        /// of the list as possible.</param>
        /// <param name="cchBufferLength">The length of the lpszVolumePathNames
        /// buffer, in TCHARs.</param>
        /// <param name="lpcchReturnLength">If the call is successful, this parameter
        /// is the number of TCHARs copied to the lpszVolumePathNames buffer. Otherwise,
        /// this parameter is the size of the buffer required to hold the complete
        /// list, in TCHARs.</param>
        /// <returns></returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        internal static extern bool GetVolumePathNamesForVolumeName(
            string lpszVolumeName, IntPtr lpszVolumePathNames, uint cchBufferLength,
            out uint lpcchReturnLength);

        /// <summary>
        /// Determines whether a disk drive is a removable, fixed, CD-ROM, RAM disk,
        /// or network drive.
        /// </summary>
        /// <param name="lpRootPathName">The root directory for the drive.
        /// 
        /// A trailing backslash is required. If this parameter is NULL, the function
        /// uses the root of the current directory.</param>
        /// <returns>The return value specifies the type of drive, which can be
        /// one of the DriveInfo.DriveType values.</returns>
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        internal static extern uint GetDriveType(string lpRootPathName);
        #endregion
    }
}