[RESOLVED] Need to get name of a USB flash drive device

[ahmd]

Hi:


I've asked this question before but did not receive an answer. Please take a look at this screenshot:
http://www.codeguru.com/forum/attach...1&d=1273174719

How to get the name of a USB flash drive device like shown there?

PS. GetVolumeInformation() returns only the volume name given to the device during formatting (and may be an empty string).

[Arjay]

What are you trying to do? Read the name of a USB device? Stop a USB device?

[ahmd]

What are you trying to do? Read the name of a USB device? Stop a USB device?

Get the list of all USB devices inserted in the system and yes, stop (or eject) any at a user's request. (I know how to eject them, so all I need is to get names.) The code currently uses GetVolumeInformation() to retrieve a USB device name but that method has a flaw when it returns an empty string for some of them.

[Arjay]

Post the code that ejects the drive and I'll see if my approach using WMI works.

[ahmd]

Here you go (all error checks are removed):

1. The drive being ejected is represented by 
   szVolumePath, format: '\\.\X:'
   szDevicePath, format: 'X:'

2. Get the volume's device number in DeviceNumber:

   HANDLE hVolume = CreateFile(szVolumePath, 0, 
	FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, 
	OPEN_EXISTING, NULL, NULL);

   STORAGE_DEVICE_NUMBER sdn;
   DeviceIoControl(hVolume, IOCTL_STORAGE_GET_DEVICE_NUMBER, NULL, 0, 
	&sdn, sizeof(sdn), &dwBytesReturned, NULL);

   CloseHandle(hVolume);

   DeviceNumber = sdn.DeviceNumber;

4. Get device instance handle in DevInst:

   DEVINST DevInst = 0;

   switch(GetDriveType(szDevicePath))
   {
      //Need only these devices
      case DRIVE_REMOVABLE:
      case DRIVE_FIXED:
        break;
      default:
	return;
   }

   HDEVINFO hDevInfo = SetupDiGetClassDevs(GUID_DEVINTERFACE_DISK,
	NULL, NULL, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);

   DWORD dwSize;
   BYTE pLargeBuffer[1024];
   SP_DEVINFO_DATA spdd;
   SP_DEVICE_INTERFACE_DATA spdid;
   PSP_DEVICE_INTERFACE_DETAIL_DATA pspdidd = (PSP_DEVICE_INTERFACE_DETAIL_DATA)pLargeBuffer;

   for(int dwIndex = 0;; dwIndex++)
   {
      if(!SetupDiEnumDeviceInterfaces(hDevInfo, NULL, GUID_DEVINTERFACE_DISK, dwIndex, &spdid))
         break;

      SetupDiGetDeviceInterfaceDetail(hDevInfo, &spdid, pspdidd, dwSize, &dwSize, &spdd);

      HANDLE hDrive = CreateFile(pspdidd->DevicePath, 0, 
         FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);

      STORAGE_DEVICE_NUMBER sdn;
      DWORD dwBytesReturned = 0;
      DeviceIoControl(hDrive, IOCTL_STORAGE_GET_DEVICE_NUMBER, 
         NULL, 0, &sdn, sizeof(sdn), &dwBytesReturned, NULL);

      CloseHandle(hDrive);

      if(DeviceNumber == sdn.DeviceNumber)
      {
         DevInst =  spdd.DevInst;
         break;
      }
   }

   SetupDiDestroyDeviceInfoList(hDevInfo);

5. Now do the ejection:

   PNP_VETO_TYPE VetoType = PNP_VetoTypeUnknown; 
   WCHAR VetoNameW[MAX_PATH] = {0};

   DEVINST DevInstParent = 0;
   CM_Get_Parent(&DevInstParent, DevInst, 0); 

   long r = CM_Request_Device_EjectW(DevInstParent, &VetoType, VetoNameW, MAX_PATH, 0);

6. See if succeeded:

   if(r == CR_SUCCESS && VetoType == PNP_VetoTypeUnknown)
       bEjectedOK = true;

[Arjay]

Do you have anything that compiles? I want to help, but I don't want to take the time to fix up the code.

[ahmd]

Do you have anything that compiles? I want to help, but I don't want to take the time to fix up the code.

...

[Arjay]

See the attached project that uses WMI to grab the info. It's a VC2008 project, so you'll have to move the stdafx.h, wmi.h, and wmitest.cpp into an earlier project.

The sample uses a WMI class that I develop here. I extended that class to handle WMI associations.

At any rate, here's the output on my machine with 3 USB drives attached:

USB Flash Memory
Removable Disk (H:)

Generic Flash Disk
USB DISK (F:)

Lexar USB Flash Drive
Lexar (I:)

Here's the relevant code:

#include "stdafx.h"
#include "wmi.h"

const LPCTSTR QueryDiskDrives	= _T("SELECT * FROM Win32_DiskDrive WHERE InterfaceType = \"USB\"");
const LPCTSTR QueryPartitions   = _T("ASSOCIATORS OF {Win32_DiskDrive.DeviceID=\"%s\"} WHERE AssocClass = Win32_DiskDriveToDiskPartition");
const LPCTSTR QueryLogicalDisks = _T("ASSOCIATORS OF {Win32_DiskPartition.DeviceID=\"%s\"} WHERE AssocClass = Win32_LogicalDiskToPartition");

void DisplayUSBDrive( CString sDrive, CString sDescription, CString sVolumeName )
{
  CString sDisplay;
  sDisplay.Format( _T("%s (%s)"), sVolumeName.GetLength( ) ? sVolumeName : sDescription, sDrive  );

  std::wcout << sDisplay.GetString( ) << std::endl << std::endl;
}

int _tmain(int argc, _TCHAR* argv[])
{
  if( FAILED( CoInitialize( NULL ) ) )
  {
    return 0;
  }

  try
  {
    CWmi wmi;

    IEnumWbemClassObjectPtr spDiskDriveEnum, spPartitionEnum, spLogicalDiskEnum;

    wmi.ExecuteQueryWMIClassObjectEnum( QueryDiskDrives, spDiskDriveEnum, WBEM_FLAG_FORWARD_ONLY );

    IWbemClassObjectPtr spDiskDrive;
    ULONG uReturned1 = 0;

    while( S_OK == spDiskDriveEnum->Next( WBEM_INFINITE, 1, &spDiskDrive, &uReturned1 ) )
   {
      CString sCaption, sDeviceID, sPNPDeviceID;

      wmi.GetPropertyString( spDiskDrive, sCaption, L"Caption" );
      wmi.GetPropertyString( spDiskDrive, sDeviceID, L"DeviceID" );
      wmi.GetPropertyString( spDiskDrive, sPNPDeviceID, L"PNPDeviceID" );

      sCaption.Replace( _T(" USB Device"), _T("") );

      std::wcout << sCaption.GetString( ) << std::endl;
      // std::wcout << L"DeviceID:    " << sDeviceID.GetString( ) << std::endl;
      // std::wcout << L"PNPDeviceID: " << sPNPDeviceID.GetString( ) << std::endl;

      sDeviceID.Replace( _T("\\"), _T("\\\\") );

      CString sPartitions;
      sPartitions.Format( QueryPartitions, sDeviceID ); 

      wmi.ExecuteQueryWMIClassObjectEnum( sPartitions.GetString( ), spPartitionEnum, WBEM_FLAG_FORWARD_ONLY );

      IWbemClassObjectPtr spPartition;

      ULONG uReturned2 = 0;
		
      while( S_OK == spPartitionEnum->Next( WBEM_INFINITE, 1, &spPartition, &uReturned2 ) )
      {
        CString sDevID;

        wmi.GetPropertyString( spPartition, sDevID, L"DeviceID" );

        CString sLogicalDisks;
        sLogicalDisks.Format( QueryLogicalDisks, sDevID ); 

        wmi.ExecuteQueryWMIClassObjectEnum( sLogicalDisks.GetString( ), spLogicalDiskEnum, WBEM_FLAG_FORWARD_ONLY );

        IWbemClassObjectPtr spLogicalDisk;

        ULONG uReturned3 = 0;

        while( S_OK == spLogicalDiskEnum->Next( WBEM_INFINITE, 1, &spLogicalDisk, &uReturned3 ) )
        {
           CString sDrive, sDescription, sVolumeName;

            wmi.GetPropertyString( spLogicalDisk, sDrive, L"DeviceID" );
            wmi.GetPropertyString( spLogicalDisk, sDescription, L"Description" );
            wmi.GetPropertyString( spLogicalDisk, sVolumeName, L"VolumeName" );

            // std::wcout << L"Drive:      " << sDrive.GetString( ) << std::endl;
            // std::wcout << L"Drive:      " << sDescription.GetString( ) << std::endl;
            // std::wcout << L"VolumeName: " << sVolumeName.GetString( ) << std::endl<< std::endl;

            DisplayUSBDrive( sDrive, sDescription, sVolumeName );
          }
        }
      }
  }
  catch( _com_error& e )
  {
    std::wcout << L"" << e.ErrorMessage( ) << std::endl;
  }

  CoUninitialize( );

  return 0;
}

__________________________________________________________
Arjay

See my latest series on using WCF to communicate between a Windows Service and WPF task bar application.
Tray Notify - Part I Tray Notify - Part II

Need a little help with Win32 thread synchronization? Check out the following CG articles and posts:
Sharing a thread safe std::queue between threads w/progress bar updating
Simple Thread: Part I Simple Thread: Part II
Win32 Thread Synchronization, Part I: Overview Win32 Thread Synchronization, Part 2: Helper Classes

www.iridyn.com



...

[Igor Vartanov]

Non-WMI version.

[ahmd]

Nice! Thank you, Arjay and Igor. Both approaches work. Now I have a new dilemma -- which method to use No, seriously, I like WMI method, it's more elegant, but on the other hand it carries a heavier overhead than Igor's Windows Driver Kit one.

[hoxsiew]

WMI is atrociously slow compared to IOCTL. I once tried to use WMI to get various hardware signatures for a machine ID for software protection. This ran before the app would come up and it was so slow what with initializing all the WMI prerequisites and all that we had to abandon it.

[Arjay]

Speed only matters if the solution works. The IOCTL approach didn't retrieve the drive letter on my 2008 R2 machine.

Not that this is a contest or anything.

[ahmd]

Yes, as I said, WMI is way too slow but in most cases it is the only way to retrieve some hardware information. My way to use it is to call it once at the app start-up, preferably in a separate thread and cache the results.

In my original question here WMI works perfectly since a small overhead doesn't matter that much.

On the side note, guys, are there lower-level APIs to WMI? Because the stuff you can get with it is amazing.

[Arjay]

To help speed things up (as you know), you can initialize WMI at app startup and keep the WMI object around.

Also, it seems that some of the WMI info (or infrastructure) is cached. I believe you will find that the first call to getting WMI info (other than initialization) takes longer than subsequent calls.

I believe the performance would be acceptable if you initialized WMI at start up and grabbed the info on demand - say to fill out a context menu. I was actually going to code up a taskbar sample with a context menu, but I got lazy.

Btw, many of what is available with WMI isn't easily obtained by other methods.

[Igor Vartanov]

The IOCTL approach didn't retrieve the drive letter on my 2008 R2 machine.

Neither on my Win7. It needs elevated level to CreateFile on device path, then works fine. No surprise.