Error: Access denied when using the function 'CreateVirtualDisk' in WIN7

Question

Hello everyone,

Right now I am experimenting with the CreateVirtualDisk function to create a VHD from both physical disk and virtual disk. I had no problem with creating a new VHD from a virtual disk, but from a physical disk, I got the error: Access is denied. I always ran the program with the administrator rights so in theory it should work out but it didn’t. I really don’t know what went wrong here.

I used the PInvoke to call this method from C#, this is how I defined the function and the relevant structure:

Definition of the function:

[DllImport ("virtdisk.dll" , CharSet = CharSet .Unicode)]

      public static extern Int32 CreateVirtualDisk(

         ref VIRTUAL_STORAGE_TYPE VirtualStorageType,

         String Path,

         _VIRTUAL_DISK_ACCESS_MASK VirtualDiskAccessMask,

         IntPtr SecurityDescriptor,

         _CREATE_VIRTUAL_DISK_FLAG Flags,

         Int32 ProviderSpecificFlags,

         ref CREATE_VIRTUAL_DISK_PARAMETERS Parameters,

         IntPtr Overlapped,

         ref VirtualDiskSafeHandle Handle);

Definition of CREATE_VIRTUAL_DISK_PARAMETER:

      public struct CREATE_VIRTUAL_DISK_PARAMETERS

      {

         /// <summary>

         /// An enum specifies the version of the CREATE_VIRTUAL_DISK_PARAMETERS structure being passed to or from the VHD functions.

         /// </summary>

         public _CREATE_VIRTUAL_DISK_VERSION Version;

 

         /// <summary>

         /// Version1

         /// </summary>

         public CREATE_VIRTUAL_DISK_PARAMETERS_VERSION1 Version1;

      }

Definition of CREATE_VIRTUAL_DISK_PARAMETER_VERSION1:

public struct CREATE_VIRTUAL_DISK_PARAMETERS_VERSION1

      {

         /// <summary>

         /// Unique identifier to assign to the virtual disk object. If this member is set to zero, a unique identifier is created by the system.

         /// </summary>

         public Guid UniqueId;

 

         /// <summary>

         /// The maximum virtual size of the virtual disk object. Must be a multiple of 512.

         /// </summary>

         public Int64 MaximumSize;

 

         /// <summary>

         /// Internal size of the virtual disk object blocks.

         /// </summary>

         public Int32 BlockSizeInBytes;

 

         /// <summary>

         /// Internal size of the virtual disk object sectors. Must be set to 512.

         /// </summary>

         public Int32 SectorSizeInBytes;

 

         /// <summary>

         /// Optional fully qualified path to a parent virtual disk object. Associates the new virtual disk with an existing virtual disk

         /// </summary>

         public IntPtr ParentPath;

 

         /// <summary>

         /// Optional fully qualified path to pre-populate the new virtual disk object with block data from an existing disk. This path may refer to a virtual disk or a physical disk.

         /// </summary>

         public IntPtr SourcePath;

      }

 

And this is how I received the error:

I set all the parameters like this:

·         VIRTUAL_STORAGE_TYPE:

o    virtualStorageType.DeviceID = VIRTUAL_STORAGE_TYPE_DEVICE_VHD;

o   virtualStorageType.VendorID = VIRTUAL_STORAGE_TYPE_VENDOR_MICROSOFT;

·         PATH:

o   m_path = “D:\VirtualDisk\test.vhd”;

·         VIRTUAL_DISK_ACCESS_MASK:

o   virtualDiskAccessMask = VIRTUAL_DISK_ACCESS_MASK.VIRTUAL_DISK_ACCESS_CREATE;

·         SECURITY_DESCRIPTOR:

o   securityDescriptor = IntPtr .Zero;

·         CREATE_VIRTUAL_DISK_FLAG:

o   createVirtualDiskFlag = CREATE_VIRTUAL_DISK_FLAG.CREATE_VIRTUAL_DISK_FLAG_FULL_PHYSICAL_ALLOCATION

·         ProviderSpecificFlag:

o   providerSpecificFlag = 0;

·         CREATE_VIRTUAL_DISK_PARAMETER:

o    m_createVirtualDiskParameters.Version = _CREATE_VIRTUAL_DISK_VERSION .CREATE_VIRTUAL_DISK_VERSION_1;

o    m_createVirtualDiskParameters.Version1.UniqueId = Guid .Empty;

o    m_createVirtualDiskParameters.Version1.MaximumSize = 0;

o    m_createVirtualDiskParameters.Version1.BlockSizeInBytes = 0;

o    m_createVirtualDiskParameters.Version1.SectorSizeInByte = VirtualDisk .CREATE_VIRTUAL_DISK_PARAMETERS_DEFAULT_SECTOR_SIZE;

o    m_createVirtualDiskParameters.Version1.ParentPath = IntPtr .Zero;

o   m_createVirtualDiskParameters.Version1.SourcePath = Marshal .StringToHGlobalAuto(sourcepath );

·         OVERLAPPED:

o   Overlapped  = IntPtr .Zero ;

·         HANDLE:

o   handle

I have tried with many values of the string variable ‘sourcepath ’ and here are the results:

1.  With the absolute path of an existing virtual disk:

sourcepath = @"D:\VirtualDisk\KarhuBearOS.vhd";

Success!

2.  With the absolute path of a physical disk:

sourcepath = @"C:\";

Failed! à Access is denied.

3.  With a volume ID created by VSS Service:

sourcepath = @"\\?\Volume{a3c3c244-8b7a-11de-a777-806e6f6e6963}\ "

Failed! à Access is denied.

4.  With the absolute path of a volume ID created by VSS Service

sourcepath = @"\\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy30\ "

Failed! à Access is denied.

 

I will greatly appreciate your help if you can show me the way to correct this problem.

My very best,

Hoang Anh Nguyen