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How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

cazorla1914-Aug-20 3:30

14-Aug-20 3:30

I am trying out VirtualDisk APIs, So far I am able to Open a VHDX file, get some of the properties by using GetVirtualDiskInformation. But I am not able to get RCT information and ChangedAreas.

1)Opendisk is done with VIRTUAL_DISK_ACCESS_GET_INFO flag.

2)GetVirtualDiskInformation
a. Works fine when version flag is set to GET_VIRTUAL_DISK_INFO_SIZE, able to fetch sector size and other information
b. Gives ERROR_INSUFFICIENT_BUFFER(122) when version flag is set to GET_VIRTUAL_DISK_INFO_CHANGE_TRACKING_STATE to access diskInfo->ChangeTrackingState.MostRecentId

PGET_VIRTUAL_DISK_INFO diskInfo;
ULONG diskInfoSize = sizeof(GET_VIRTUAL_DISK_INFO);
std::wcout << "size of diskinfo structure " << diskInfoSize << std::endl;
diskInfo = (PGET_VIRTUAL_DISK_INFO)malloc(diskInfoSize);

diskInfo->Version = GET_VIRTUAL_DISK_INFO_SIZE;

res = GetVirtualDiskInformation(vhdHandle, &diskInfoSize, diskInfo, NULL);
long physicalSize = diskInfo->Size.PhysicalSize;
long virtualSize = diskInfo->Size.VirtualSize;
long sectorSize = diskInfo->Size.SectorSize;
long blockSize = diskInfo->Size.BlockSize;
std::wcout << "physicalSize :" << physicalSize << std::endl;
std::wcout << "virtualSize :" << virtualSize << std::endl;
std::wcout << "sectorSize :" << sectorSize << std::endl;
std::wcout << "blockSize :" << blockSize << std::endl;

diskInfo->Version = GET_VIRTUAL_DISK_INFO_CHANGE_TRACKING_STATE;

res = GetVirtualDiskInformation(vhdHandle, &diskInfoSize, diskInfo, NULL);
std::wcout << "\nrct id:" << diskInfo->ChangeTrackingState.MostRecentId << std::endl;

3)queryChangesVirtualDisk gives ACCESS DENIED.

ULONG64   byteOffset = 0L;
ULONG64   byteLength = 19327352832;
QUERY_CHANGES_VIRTUAL_DISK_RANGE* changedAreas = NULL;
ULONG     rangeCount = 0L;
ULONG64   processedLength = 0L;
res = QueryChangesVirtualDisk(vhdHandle, "rctX:c2eb01d9:ccb1:405d:acb6:f0e76d055906:00000001",
    byteOffset, byteLength,
    QUERY_CHANGES_VIRTUAL_DISK_FLAG_NONE,
    changedAreas, &rangeCount, &processedLength);

Can someone please give some ideas on what I am doing wrong?

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

Gerry Schmitz14-Aug-20 5:04

Gerry Schmitz

14-Aug-20 5:04

Quote:
This value is not supported before Windows 10 and Windows Server 2016.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

cazorla1918-Aug-20 0:57

cazorla19

18-Aug-20 0:57

Hi Gerry,

I am trying in a Windows2016 hyperV, and guest VM has windows 10.
Also, I am able to get changed blocks by using WMI queries.
But VHD API is giving ACCESS_DENIED_ERROR.

Regards,
Hari

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

Gerry Schmitz18-Aug-20 5:34

Gerry Schmitz

18-Aug-20 5:34

The first thing I'd do is confirm "without" a VM. And then I'd try Oracle's VmBox. Then try running as "admin" in the VM, etc.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

Randor 14-Aug-20 8:54

Randor

14-Aug-20 8:54

Hi,

I do see at least one problem in your code:

C++

ULONG diskInfoSize = sizeof(GET_VIRTUAL_DISK_INFO);

should be changed to:

C++

ULONG diskInfoSize = sizeof(GET_VIRTUAL_DISK_INFO) + sizeof(GUID);

cazorla19 wrote:
queryChangesVirtualDisk gives ACCESS DENIED.

Could you show me the flags you are passing to OpenVirtualDisk?

Best Wishes,
-David Delaune

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

cazorla1918-Aug-20 0:55

cazorla19

18-Aug-20 0:55

Hi David,

I have tried OpenVirtualDisk with VIRTUAL_DISK_ACCESS_GET_INFO as suggested in msdn portal.
I also tried with VIRTUAL_DISK_ACCESS_READ, both times I got same error.

OPEN_VIRTUAL_DISK_PARAMETERS openParameters;
openParameters.Version = OPEN_VIRTUAL_DISK_VERSION_1;
openParameters.Version1.RWDepth = OPEN_VIRTUAL_DISK_RW_DEPTH_DEFAULT;
_VIRTUAL_STORAGE_TYPE storageType;
storageType.DeviceId = VIRTUAL_STORAGE_TYPE_DEVICE_UNKNOWN;
storageType.VendorId = VIRTUAL_STORAGE_TYPE_VENDOR_UNKNOWN;

DWORD res = OpenVirtualDisk(&storageType, path,
     VIRTUAL_DISK_ACCESS_GET_INFO,
     OPEN_VIRTUAL_DISK_FLAG_NONE,
     &openParameters,
     &vhdHandle);

Also, I changed diskInfoSize as suggested but still got the same 'insufficient buffer size' error.

ULONG diskInfoSize = sizeof(GET_VIRTUAL_DISK_INFO) + sizeof(GUID);

Increasing the diskinfo size definitely helped me in getting rct id using GetVirtualDiskInformation,

WCHAR changeTrackingInfo[2048];
ZeroMemory(changeTrackingInfo, sizeof(changeTrackingInfo));

PGET_VIRTUAL_DISK_INFO diskInfo;
ULONG diskInfoSize = sizeof(GET_VIRTUAL_DISK_INFO) + sizeof(changeTrackingInfo);

queryChangesVirtualDisk gives ACCESS DENIED is not resolved.

Regards,
Hari

modified 19-Aug-20 1:59am.

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

Randor 19-Aug-20 19:04

Randor

19-Aug-20 19:04

Hi Hari,

Kinda looks like you are breaking the rules of nearly everything in the Remarks section for the OpenVirtualDisk function for a permanently attached virtual disk.

This is working for me, code is ugly, there is no error handling... it's just a code sample:

C++

#include <iostream>
#include <windows.h>
#include <virtdisk.h>
#include <tchar.h>
#include <comdef.h>
#include <atlcomcli.h>
#include <wbemidl.h>

#pragma comment(lib, "wbemuuid.lib")
#pragma comment(lib, "virtdisk.lib")

const GUID VIRTUAL_STORAGE_TYPE_VENDOR_MICROSOFT = {0xec984aec, 0xa0f9, 0x47e9, 0x90, 0x1f, 0x71, 0x41, 0x5a, 0x66, 0x34, 0x5b};
const GUID VIRTUAL_STORAGE_TYPE_VENDOR_UNKNOWN = { 0x00000000, 0x0000, 0x0000, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

int main()
{
	HANDLE vhdHandle = NULL;
	VIRTUAL_STORAGE_TYPE storageType = {};
	ULONG  status = 0L;

	//storageType.DeviceId = VIRTUAL_STORAGE_TYPE_DEVICE_VHDX;
	//storageType.VendorId = VIRTUAL_STORAGE_TYPE_VENDOR_MICROSOFT;
	storageType.DeviceId = VIRTUAL_STORAGE_TYPE_DEVICE_UNKNOWN;
	storageType.VendorId = VIRTUAL_STORAGE_TYPE_VENDOR_UNKNOWN;

	PCWSTR virtualDiskPath = L"D:\\VirtualMachines\\x64_Windows8.1\\x64_Windows8.1\\Virtual Hard Disks\\x64_Windows8.1.vhdx";

	OPEN_VIRTUAL_DISK_PARAMETERS* pOpenParameter = NULL;

	status = OpenVirtualDisk(&storageType, virtualDiskPath,VIRTUAL_DISK_ACCESS_ATTACH_RW | VIRTUAL_DISK_ACCESS_GET_INFO | VIRTUAL_DISK_ACCESS_DETACH,OPEN_VIRTUAL_DISK_FLAG_NONE, pOpenParameter, &vhdHandle);

	if (ERROR_SUCCESS == status)
	{
		DWORD sizeUsed = GET_VIRTUAL_DISK_INFO_SIZE;
		WCHAR changeTrackingInfo[sizeof(GET_VIRTUAL_DISK_INFO) + sizeof(GUID)];
		::ZeroMemory(changeTrackingInfo, sizeof(changeTrackingInfo));
		PGET_VIRTUAL_DISK_INFO virtualDiskInfo = (GET_VIRTUAL_DISK_INFO*)changeTrackingInfo;
		virtualDiskInfo->Version = (GET_VIRTUAL_DISK_INFO_VERSION)GET_VIRTUAL_DISK_INFO_CHANGE_TRACKING_STATE;
		ULONG virtualDiskInfoSize = sizeof(changeTrackingInfo);

		status = GetVirtualDiskInformation(vhdHandle, &virtualDiskInfoSize, virtualDiskInfo, &sizeUsed);

		if (ERROR_SUCCESS == status)
		{
			ULONG64 virtualDiskSize = virtualDiskInfo->Size.VirtualSize;

			printf("Disk Infomation:\n");
			GUID virtualDiskGuid = virtualDiskInfo->Identifier;
			wchar_t szGUID[64] = { 0 };
			StringFromGUID2(virtualDiskGuid, szGUID, 64);
			wprintf(L"ChangeTrackingState.Enabled:%d\n", virtualDiskInfo->ChangeTrackingState.Enabled);
			wprintf(L"ChangeTrackingState.MostRecentId:%s\n", virtualDiskInfo->ChangeTrackingState.MostRecentId);
			wprintf(L"Identifier\t= %s\n", szGUID);
			wprintf(L"Physical Size\t= %I64u\n", virtualDiskInfo->Size.PhysicalSize);
			wprintf(L"Virtual Size\t= %I64u\n", virtualDiskInfo->Size.VirtualSize);
			wprintf(L"Sector Size\t= %u\n", virtualDiskInfo->Size.SectorSize);
			wprintf(L"Block Size\t= %u\n", virtualDiskInfo->Size.BlockSize);
		}
	}
	return 0;
}

Best Wishes,
-Rubeus Hagrid

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

cazorla1919-Aug-20 20:26

cazorla19

19-Aug-20 20:26

Many thanks for your inputs.
Tried your sample code in my environment, OpenVirtualDisk failed with 32 ERROR_SHARING_VIOLATION.

Steps I have followed till now,
1. Create a production snapshot on the VM.
2. Convert the snapshot to the reference point(snapshot gets merged automatically) using wmi commands.
3. Added some files to VM disk.
4. Create another production snapshot on the VM so that any changes in VM will be written to avhdx file.
5. Try to open the parent vhdx using VHD APIs.
6. Get a resilient change tracking identifier using ChangeTrackingState.MostRecentId
7. Query for changed areas using VHD API QueryChangesVirtualDisk.

So far I am able to get till step six by passing only VIRTUAL_DISK_ACCESS_GET_INFO flag for OpenVirtualDisk. step 7 gives ACCESS_DENIED.

void openDiskEx()
{
    HANDLE vhdHandle = NULL;
    VIRTUAL_STORAGE_TYPE storageType = {};
    ULONG  status = 0L;

    storageType.DeviceId = VIRTUAL_STORAGE_TYPE_DEVICE_UNKNOWN;
    storageType.VendorId = VIRTUAL_STORAGE_TYPE_VENDOR_UNKNOWN;

    PCWSTR virtualDiskPath = L"C:\\Hyper-V\\Virtual Hard Disks\\Lacazette\\Windows2016.vhdx";

    OPEN_VIRTUAL_DISK_PARAMETERS* pOpenParameter = NULL;

    status = OpenVirtualDisk(&storageType, virtualDiskPath, VIRTUAL_DISK_ACCESS_ATTACH_RW | VIRTUAL_DISK_ACCESS_GET_INFO | VIRTUAL_DISK_ACCESS_DETACH, OPEN_VIRTUAL_DISK_FLAG_NONE, pOpenParameter, &vhdHandle);
    std::cout << "opendisk:" << status<< std::endl;
    if (ERROR_SUCCESS == status)
    {
        DWORD sizeUsed = GET_VIRTUAL_DISK_INFO_SIZE;
        WCHAR changeTrackingInfo[sizeof(GET_VIRTUAL_DISK_INFO) + sizeof(GUID)];
        ::ZeroMemory(changeTrackingInfo, sizeof(changeTrackingInfo));
        PGET_VIRTUAL_DISK_INFO virtualDiskInfo = (GET_VIRTUAL_DISK_INFO*)changeTrackingInfo;
        virtualDiskInfo->Version = (GET_VIRTUAL_DISK_INFO_VERSION)GET_VIRTUAL_DISK_INFO_CHANGE_TRACKING_STATE;
        ULONG virtualDiskInfoSize = sizeof(changeTrackingInfo);

        status = GetVirtualDiskInformation(vhdHandle, &virtualDiskInfoSize, virtualDiskInfo, &sizeUsed);
        std::cout << "GetVirtualDiskInformation:" << status << std::endl;
        if (ERROR_SUCCESS == status)
        {
            ULONG64 virtualDiskSize = virtualDiskInfo->Size.VirtualSize;
            printf("Disk Infomation:\n");
            GUID virtualDiskGuid = virtualDiskInfo->Identifier;
            wchar_t szGUID[64] = { 0 };
            StringFromGUID2(virtualDiskGuid, szGUID, 64);
            wprintf(L"ChangeTrackingState.Enabled:%d\n", virtualDiskInfo->ChangeTrackingState.Enabled);
            wprintf(L"ChangeTrackingState.MostRecentId:%s\n", virtualDiskInfo->ChangeTrackingState.MostRecentId);
            wprintf(L"Identifier\t= %s\n", szGUID);
            wprintf(L"Physical Size\t= %I64u\n", virtualDiskInfo->Size.PhysicalSize);
            wprintf(L"Virtual Size\t= %I64u\n", virtualDiskInfo->Size.VirtualSize);
            wprintf(L"Sector Size\t= %u\n", virtualDiskInfo->Size.SectorSize);
            wprintf(L"Block Size\t= %u\n", virtualDiskInfo->Size.BlockSize);
        }
    }
    CloseHandle(vhdHandle);
}

Regards,
Hari

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

Randor 19-Aug-20 20:57

Randor

19-Aug-20 20:57

cazorla19 wrote:
OpenVirtualDisk failed with 32 ERROR_SHARING_VIOLATION.

That obviously means that the virtual disk is locked/mounted and being used by another process. Are you trying to read the change tracking on running Hyper-V virtual machine? I don't think you can do that.

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

cazorla1919-Aug-20 21:29

cazorla19

19-Aug-20 21:29

Yes, I am trying to read the change tracking information when the Virtual machine is online.

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

Randor 19-Aug-20 21:47

Randor

19-Aug-20 21:47

Ok,

If you can't read the change tracking information from an Administrator account with both SE_BACKUP_NAME and SE_MANAGE_VOLUME_NAME privileges then I don't think it will be possible. Also since the virtual drive is mounted you should change the access mask from VIRTUAL_DISK_ACCESS_ATTACH_RW to VIRTUAL_DISK_ACCESS_ATTACH_RO.

I am actually in a Hyper-V environment right now so if I get some time later today I will look into it more. The code sample I gave you is working for me on my offline virtual machines.

Best Wishes,
-David Delaune

Re: How to get allocated blocks for VHDx? queryChangesVirtualDisk gives ACCESS DENIED.

DingHuaming17-Jul-24 18:35

DingHuaming

17-Jul-24 18:35

hi, have you resolve the problem?

Microsoft Media Foundation AAC Decoder using C++

sabid12-Aug-20 18:32

sabid

12-Aug-20 18:32

How can I convert AAC file Wav file using C++ and Microsoft Media Foundation?

Re: Microsoft Media Foundation AAC Decoder using C++

Richard MacCutchan12-Aug-20 21:04

Richard MacCutchan

12-Aug-20 21:04

Study the documentation for the two file types. Then study the documentation for the framework you plan to use.

Re: Microsoft Media Foundation AAC Decoder using C++

11917640 Member 2-Sep-20 1:06

11917640 Member

2-Sep-20 1:06

Some useful Media Foundation resources:

Windows-classic-samples, Media Foundation. GitHub[^]

Samples from Media Foundation Team Blog[^]

Developing Microsoft Media Foundation Applications (Developer Reference)[^] This book contains the sample code available for downloading.

Tanta, Windows Media Foundation Sample Projects[^]

Hopefully, you will find something similar to your task.

Is there an entry point for CppUnitTestFramework unit tests ?

Maximilien11-Aug-20 10:01

Maximilien

11-Aug-20 10:01

I need to initialize a 3rd party library when doing some/most of our unit tests.

We have a working homemade framework with an entry point (_tmain) where we can do all initialization for all our tests.

I can't seem to find the equivalent with CppUnitTestFramework.

I don't want to add a wrapper to do the 3rd party library initialization for each unit test.

Can I do such a thing ?

Thanks.

I'd rather be phishing!

Re: Is there an entry point for CppUnitTestFramework unit tests ?

Richard MacCutchan11-Aug-20 22:23

Richard MacCutchan

11-Aug-20 22:23

Try the CppUnitTestFramework API - Initialize_and_cleanup[^].

Re: Is there an entry point for CppUnitTestFramework unit tests ?

Maximilien12-Aug-20 7:31

Maximilien

12-Aug-20 7:31

Thanks,
I will look into it, but it seems to be run for each test and is not global to all my test cases and test classes. ?

"Defines methodName as a method that runs before each test method is run. TEST_METHOD_INITIALIZE can only be defined once in a test class and must be defined in the scope of the test class."

I'd rather be phishing!

computer science

Member 1491094810-Aug-20 0:26

Member 14910948

10-Aug-20 0:26

An engineer stores a FIFO queue of bit in an int on a platform with 32bit ints and 8-bit chars using the following C++ class
Class bit queue{
Int valid_bits;   //the number of valid bits held in queue
Int queue;        //least significant bits is most recent bit added
Public:
Bitqueue(): valid_bits(0), queue(0) {}
Void push(int val, int bsize);
Int pop(int bsize);
Int size();
};

1.Write implementation of bitqueue::size which should return the number of bits currently held in queue
2.Write an implementation of bitqueue::push which places the bsize least significant bits from val onto queue and update valid bits. An exception should be thrown in cases where data would otherwise be lost.
3.Write an implementation of bitqueue::pop which takes bsize bits from queue, provides them as the bsize least significant bits in the return value and updated valid bits. An exception should be thrown when any requested data is unavailable.

Re: computer science

Daniel Pfeffer10-Aug-20 0:45

Daniel Pfeffer

10-Aug-20 0:45

We do not do people's homework.

The idea of homework is to improve your understanding and skills. Having someone else do it for you misses the point, and gives your instructor and anyone else looking at your grades a false idea of your competence.

Try to solve the problem on your own. If you run into problems, come back, post your code, and ask how to solve the specific problem that you are having with your code. You will then find that people are happy to help you.

Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.

Re: computer science

Richard MacCutchan10-Aug-20 3:24

Richard MacCutchan

10-Aug-20 3:24

I don't know where this came from, but it needs correcting before you start. The terms Class, Int, Public and Void are all incorrectly spelled. The correct forms are class, int, public and void; all lower case. Also the class definition is incorrect. You have Class bit queue, but class names are only one word. You also name the constructor Bitqueue, which may or may not match the correct class name. So there is really a lot to learn before you can venture into trying to solve this question.

sorce code grid line

SADEGH20771-Aug-20 7:44

SADEGH2077

1-Aug-20 7:44

You can help me gird line opengl cli I got it

Re: sorce code grid line

Victor Nijegorodov1-Aug-20 8:15

Victor Nijegorodov

1-Aug-20 8:15

Is it a question or an assertion? Confused | :confused: