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Detecting when drives are added or removed

, 4 Jul 2007
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Dealing with the WM_DEVICECHANGE message to detect volumes being added or removed.

Screenshot - Drive_Detect.jpg

Introduction

This is possibly my smallest article, and just shows a method of detecting when drives are added to or removed from the system. What you do with that information is up to you!

Background

I was answering a question from Akin Ocal yesterday, when Matthew Faithful came up with a much deeper answer than mine.

In a fit of pique / curiosity, I thought I'd come up with a different way of doing what he described, using Windows messages to do the heavy lifting. As I had to do a bit of digging from barely remembered details, I thought I'd share the work with others.

Using the code

I created a blank MFC dialog project, and added a handler for WM_DEVICECHANGE. The MFC handler structure exists, but it could not be added with the Class Wizard, so I typed it in manually.

ON_WM_DEVICECHANGE ()

I then added the actual handler, which does nothing except log the fact that a drive has been added or removed.

BOOL CDriveDetectDlg::OnDeviceChange( UINT nEventType, DWORD dwData )
{
    BOOL bReturn = CWnd::OnDeviceChange (nEventType, dwData);

    DEV_BROADCAST_VOLUME *volume = (DEV_BROADCAST_VOLUME *)dwData;
    CString log;

    if (nEventType == DBT_DEVICEARRIVAL)
    {
        if (volume->dbcv_devicetype == DBT_DEVTYP_VOLUME)
        {
            for (int n = 0; n < 32; n++)
            {
                if (IsBitSet (volume->dbcv_unitmask, n))
                {
                    log.Format ("Drive %c: Inserted\n", n + 'A');
                    m_DetectLog.AddString (log);
                }
            }
        }
    }

    if (nEventType == DBT_DEVICEREMOVECOMPLETE)
    {
        if (volume->dbcv_devicetype == DBT_DEVTYP_VOLUME)
        {
            for (int n = 0; n < 32; n++)
            {
                if (IsBitSet (volume->dbcv_unitmask, n))
                {
                    log.Format ("Drive %c: Removed\n", n + 'A');
                    m_DetectLog.AddString (log);
                }
            }
        }
    }

    return bReturn;
}

As you can see, there's not a vast amount of code for the job.

Updates

  • 27/6/2007 - Little drive icons added next to the drives being added / removed. The credit for steering me in the right direction (and providing some code for me to steal^h^h^h^h^hreuse) goes to dgendreau.
  • 20/6/2007 - Original version posted.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Iain Clarke, Warrior Programmer
Software Developer (Senior)
Sweden Sweden
I have now moved to Sweden for love, and recently married a lovely Swede.
 

-----------------
I started programming on BBC micros (6502) when I was six and never quite stopped even while I was supposed to be studying physics and uni.
 
I've been working for ~13 years writing software for machine control and data analysis. I now work on financial transaction transformation software, for a Software company in Gamlastan, Stockholm.
Look at my articles to see my excellent coding skills. I'm modest too!

Comments and Discussions

 
GeneralMy vote of 5 Pinmembermanoj kumar choubey18-Feb-12 0:02 
QuestionThis code does exactly what I need but the problem is with the MFC components used in it. I need to write the code in Embarcadero c++ builder, can anybody provide suggestions about how to modify the code? PinmemberlilyNaz25-Oct-11 20:15 
AnswerRe: This code does exactly what I need but the problem is with the MFC components used in it. I need to write the code in Embarcadero c++ builder, can anybody provide suggestions about how to modify the code? PinmemberIain Clarke, Warrior Programmer12-Dec-11 4:27 
GeneralShame : copy from MSDN ... Pinmemberkilt8-Oct-09 23:32 
GeneralRe: Shame : copy from MSDN ... PinmvpIain Clarke, Warrior Programmer13-Oct-09 4:31 
QuestionFound a bug on Win2000 Pinmemberwangk070529-Dec-07 2:54 
GeneralRe: Found a bug on Win2000 PinmemberIain Clarke1-Feb-08 3:55 
GeneralDBT_DEVICEQUERYREMOVE support Pinmember64BitWho12-Oct-07 1:13 
GeneralRe: DBT_DEVICEQUERYREMOVE support PinmemberIain Clarke12-Oct-07 4:12 
GeneralRe: DBT_DEVICEQUERYREMOVE support Pinmember64BitWho12-Oct-07 4:48 
GeneralRe: DBT_DEVICEQUERYREMOVE support Pinmember64BitWho13-Oct-07 4:23 
QuestionRe: DBT_DEVICEQUERYREMOVE support PinmemberMember 43522244-Sep-08 2:10 
GeneralRe: DBT_DEVICEQUERYREMOVE support PinmemberMember 43522244-Sep-08 2:20 
GeneralRe: DBT_DEVICEQUERYREMOVE support PinmemberIain Clarke7-Sep-08 22:40 
GeneralRe: DBT_DEVICEQUERYREMOVE support PinmemberIain Clarke7-Sep-08 22:43 
GeneralRe: DBT_DEVICEQUERYREMOVE support PinmemberMember 43522247-Sep-08 23:52 
JokeRe: DBT_DEVICEQUERYREMOVE support PinmemberMember 229365217-Sep-09 18:23 
QuestionWM_DEVICECHANGE Ok! But what about Linux? PinmemberPeterShilkin12-Jul-07 1:11 
AnswerRe: WM_DEVICECHANGE Ok! But what about Linux? PinmemberIain Clarke14-Jul-07 3:53 
GeneralMissing file PinmemberXaRoP4-Jul-07 7:08 
GeneralRe: Missing file PinmemberIain Clarke4-Jul-07 10:35 
GeneralRe: Missing file PinmemberIain Clarke4-Jul-07 22:21 
QuestionWhat about insert devices PinmemberVC Spark3-Jul-07 2:28 
AnswerRe: What about insert devices PinmemberIain Clarke3-Jul-07 4:16 
GeneralRe: What about insert devices PinmemberVC Spark4-Jul-07 2:32 

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