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PhysicalDisk and Volume Mapping information

After a long time, writing this post on Windows Disk Management. I was playing with volume management APIs and found it's quite easy to get some useful information like, how I know what are the volume(s) present on a physical disk. I'm talking about a hard drive here. Of course, the Windows disk manager will reveal it but why not I should have my own app. There are Windows Volume Management APIs including the very famous CreateFile API, which is one of the amazing APIs on Windows provided by Microsoft.

The objective was to build a tool that will tell How many HDDs are attached to the system with volume information. Here is the complete code:



const int BUFF_SIZE           = 512;
const int STR_SIZE              = 20;
const int DRIVE_ID_BUFF = 3;

int _tmain(int argc, _TCHAR* argv[])
{
    TCHAR szTemp[BUFF_SIZE];
    
    if (GetLogicalDriveStrings(BUFF_SIZE - 1, szTemp)) 
    {
        TCHAR szDrive[DRIVE_ID_BUFF] = TEXT(" :");
        TCHAR* pDrive = szTemp;

        std::multimap < DWORD, TCHAR * > mapDriveVolume;
        std::map < DWORD, DWORD > mapPhysicaDriveCnt;
        HANDLE   hLogicalDisk    =    INVALID_HANDLE_VALUE;
        
        while(*pDrive)
        {
            pDrive += _tcslen( pDrive ) + 1;

            *szDrive = *pDrive;

            TCHAR szLogicalDrive[STR_SIZE];
            memset(szLogicalDrive, 0, STR_SIZE);
            _tcscpy_s(szLogicalDrive, STR_SIZE, _T("\\\\.\\"));
            _tcscat_s(szLogicalDrive, STR_SIZE, szDrive);
            
            if(_tcscmp(szLogicalDrive, _T("\\\\.\\")) != 0)
            {
                BOOL bResult            =    FALSE; // results flag
                VOLUME_DISK_EXTENTS    vDiskExtent = {0};
                DWORD bytesReturned        = 0;
                
                hLogicalDisk = CreateFileW(szLogicalDrive,     // drive to open
                            0,            // no access to the drive
                            FILE_SHARE_READ |    // share mode
                            FILE_SHARE_WRITE, 
                            NULL,            // default security attributes
                            OPEN_EXISTING,        // disposition
                            0,                // file attributes
                            NULL);

                if(INVALID_HANDLE_VALUE == hLogicalDisk)
                {
                    wprintf(L"Error in CreateFile() API with error: %ld\n", GetLastError());
                }
                else
                {
                    bResult = bResult = DeviceIoControl(hLogicalDisk,            // device to be queried
                                IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS,        // operation to perform
                                NULL, 0,                    // no input buffer
                                &vDiskExtent, sizeof(VOLUME_DISK_EXTENTS),    // output buffer
                                &bytesReturned,                    // # bytes returned
                                (LPOVERLAPPED) NULL);                // synchronous I/O
                }

                LARGE_INTEGER extLength = vDiskExtent.Extents->ExtentLength;
                if(extLength.QuadPart > 0)
                {
                    // This is a valid volume
                    
                    mapDriveVolume.insert(std::pair < DWORD, TCHAR * >(vDiskExtent.Extents->DiskNumber, pDrive));
                    mapPhysicaDriveCnt.insert(std::pair < DWORD, DWORD >(vDiskExtent.Extents->DiskNumber, vDiskExtent.Extents->DiskNumber));
                }
            }

            CloseHandle(hLogicalDisk);
        }    // End of while

        for( std::map < DWORD, DWORD >::iterator ii = mapPhysicaDriveCnt.begin(); ii != mapPhysicaDriveCnt.end(); ++ii)
        {
            wprintf(L"Number of volume in physical drive %ld is %ld\n", (*ii).first, mapDriveVolume.count((*ii).first));
            
            std::pair < std::multimap >DWORD, TCHAR * >::iterator, std::multimap>DWORD, TCHAR * >::iterator > ret;
            ret = mapDriveVolume.equal_range((*ii).first);
            
            for (std::multimap < DWORD, TCHAR * >::iterator it=ret.first; it!=ret.second; ++it)
            {
                wprintf(L"Volumes in physical drive: %ld is/are %s\n", it->first, it->second);
            }
            wprintf(L"\n");
        }
    }

    return 0;
}


The output will be like the below:



















































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