Using DeviceIoControl()

// ---------------------------------------------------------------------------/*This example succeeds only when it runs on Windows NT/Windows 2000, for tworeasons:The standard device input/output control codes are available only on WindowsNT/Windows 2000.On Microsoft® Windows® 95/98, an application must specify a virtual devicedriver in the CreateFile function - not a specific device.*/#include <windows.h>#include <winioctl.h>BOOLGetDriveGeometry(DISK_GEOMETRY *pdg){  HANDLE hDevice;               // handle to the drive to be examined  BOOL bResult;                 // results flag  DWORD junk;                   // discard results  hDevice = CreateFile("\\\\.\\PhysicalDrive0", // drive to open                       0,       // don't need any access to the drive                       FILE_SHARE_READ | FILE_SHARE_WRITE,  // share mode                       NULL,    // default security attributes                       OPEN_EXISTING,  // disposition                       0,       // file attributes                       NULL);   // don't copy any file's attributes  if (hDevice == INVALID_HANDLE_VALUE) // we can't open the drive  {    return (FALSE);  }  bResult = DeviceIoControl(hDevice,  // device we are querying      IOCTL_DISK_GET_DRIVE_GEOMETRY,  // operation to perform                             NULL, 0, // no input buffer, so pass zero                            pdg, sizeof(*pdg),  // output buffer                            &junk, // discard count of bytes returned                            (LPOVERLAPPED) NULL);  // synchronous I/O  if (!bResult) // IOCTL failed  {    return (FALSE);  }  CloseHandle(hDevice);         // we're done with the handle  return (bResult);}intmain(int argc, char *argv[]){  DISK_GEOMETRY pdg;            // disk drive geometry structure  BOOL bResult;                 // generic results flag  ULONGLONG DiskSize;           // holder for the size of the drive in bytes  bResult = GetDriveGeometry (&pdg);  if (bResult)  {    printf("Cylinders = %I64d\n", pdg.Cylinders);    printf("Tracks per cylinder = %ld\n", (ULONG) pdg.TracksPerCylinder);    printf("Sectors per track = %ld\n", (ULONG) pdg.SectorsPerTrack);    printf("Bytes per sector = %ld\n", (ULONG) pdg.BytesPerSector);    DiskSize = pdg.Cylinders.QuadPart * (ULONG)pdg.TracksPerCylinder *      (ULONG)pdg.SectorsPerTrack * (ULONG)pdg.BytesPerSector;    printf("Disk size = %I64d (Bytes) = %I64d (Mb)\n", DiskSize,           DiskSize / (1024 * 1024));  } else {    printf ("Attempt to get drive geometry failed. Error %ld.\n",            GetLastError ());  }  return ((int)bResult);}