Detect USB drive insertion in C (Windows)

Question

I tried looking around and found a few solutions to detect a USB drive insertion, but none that I found were actually working in C.

I wanted to ask, how do I approach this problem? What is the idea behind the detection process (Like, how is it done) ?

Thank you in advance! :)

Answer 1

The example at link https://msdn.microsoft.com/en-us/library/windows/desktop/aa363432(v=vs.85).aspx, given by Weather Vane, works in plain C, as I said in comments, with simple modifications.

Below there is the working modified code.

#define UNICODE 1
#define _UNICODE 1
#include <windows.h>
#include <stdio.h>
#include <tchar.h>
#include <strsafe.h>
#include <dbt.h>
#pragma comment(lib, "user32.lib" )
#pragma comment(lib, "Shell32.lib" )

void Main_OnDeviceChange( HWND hwnd, WPARAM wParam, LPARAM lParam );
char FirstDriveFromMask( ULONG unitmask );  //prototype


// This GUID is for all USB serial host PnP drivers, but you can replace it 
// with any valid device class guid.
GUID WceusbshGUID = { 0x25dbce51, 0x6c8f, 0x4a72, 
                      0x8a,0x6d,0xb5,0x4c,0x2b,0x4f,0xc8,0x35 };

// For informational messages and window titles
PWSTR g_pszAppName;

// Forward declarations
void OutputMessage(HWND hOutWnd, WPARAM wParam, LPARAM lParam);
void ErrorHandler(LPTSTR lpszFunction);

//
// DoRegisterDeviceInterfaceToHwnd
//
BOOL DoRegisterDeviceInterfaceToHwnd( 
    IN GUID InterfaceClassGuid, 
    IN HWND hWnd,
    OUT HDEVNOTIFY *hDeviceNotify 
)
// Routine Description:
//     Registers an HWND for notification of changes in the device interfaces
//     for the specified interface class GUID. 

// Parameters:
//     InterfaceClassGuid - The interface class GUID for the device 
//         interfaces. 

//     hWnd - Window handle to receive notifications.

//     hDeviceNotify - Receives the device notification handle. On failure, 
//         this value is NULL.

// Return Value:
//     If the function succeeds, the return value is TRUE.
//     If the function fails, the return value is FALSE.

// Note:
//     RegisterDeviceNotification also allows a service handle be used,
//     so a similar wrapper function to this one supporting that scenario
//     could be made from this template.
{
    DEV_BROADCAST_DEVICEINTERFACE NotificationFilter;

    ZeroMemory( &NotificationFilter, sizeof(NotificationFilter) );
    NotificationFilter.dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
    NotificationFilter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
    NotificationFilter.dbcc_classguid = InterfaceClassGuid;

    *hDeviceNotify = RegisterDeviceNotification( 
        hWnd,                       // events recipient
        &NotificationFilter,        // type of device
        DEVICE_NOTIFY_WINDOW_HANDLE // type of recipient handle
        );

    if ( NULL == *hDeviceNotify ) 
    {
        ErrorHandler(TEXT("RegisterDeviceNotification"));
        return FALSE;
    }

    return TRUE;
}

//
// MessagePump
//
void MessagePump(
    HWND hWnd
)
// Routine Description:
//     Simple main thread message pump.
//

// Parameters:
//     hWnd - handle to the window whose messages are being dispatched

// Return Value:
//     None.
{
    MSG msg; 
    int retVal;

    // Get all messages for any window that belongs to this thread,
    // without any filtering. Potential optimization could be
    // obtained via use of filter values if desired.

    while( (retVal = GetMessage(&msg, NULL, 0, 0)) != 0 ) 
    { 
        if ( retVal == -1 )
        {
            ErrorHandler(TEXT("GetMessage"));
            break;
        }
        else
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    } 
}

//
// WinProcCallback
//
INT_PTR WINAPI WinProcCallback(
                              HWND hWnd,
                              UINT message,
                              WPARAM wParam,
                              LPARAM lParam
                              )
// Routine Description:
//     Simple Windows callback for handling messages.
//     This is where all the work is done because the example
//     is using a window to process messages. This logic would be handled 
//     differently if registering a service instead of a window.

// Parameters:
//     hWnd - the window handle being registered for events.

//     message - the message being interpreted.

//     wParam and lParam - extended information provided to this
//          callback by the message sender.

//     For more information regarding these parameters and return value,
//     see the documentation for WNDCLASSEX and CreateWindowEx.
{
    LRESULT lRet = 1;
    static HDEVNOTIFY hDeviceNotify;
    static HWND hEditWnd;
    static ULONGLONG msgCount = 0;

    switch (message)
    {
    case WM_CREATE:
        //
        // This is the actual registration., In this example, registration 
        // should happen only once, at application startup when the window
        // is created.
        //
        // If you were using a service, you would put this in your main code 
        // path as part of your service initialization.
        //
        if ( ! DoRegisterDeviceInterfaceToHwnd(
                        WceusbshGUID, 
                        hWnd,
                        &hDeviceNotify) )
        {
            // Terminate on failure.
            ErrorHandler(TEXT("DoRegisterDeviceInterfaceToHwnd"));
            ExitProcess(1);
        }


        //
        // Make the child window for output.
        //
        hEditWnd = CreateWindow(TEXT("EDIT"),// predefined class 
                                NULL,        // no window title 
                                WS_CHILD | WS_VISIBLE | WS_VSCROLL | 
                                ES_LEFT | ES_MULTILINE | ES_AUTOVSCROLL, 
                                0, 0, 0, 0,  // set size in WM_SIZE message 
                                hWnd,        // parent window 
                                (HMENU)1,    // edit control ID 
                                (HINSTANCE) GetWindowLong(hWnd, GWL_HINSTANCE), 
                                NULL);       // pointer not needed 

        if ( hEditWnd == NULL )
        {
            // Terminate on failure.
            ErrorHandler(TEXT("CreateWindow: Edit Control"));
            ExitProcess(1);
        }
        // Add text to the window. 
        SendMessage(hEditWnd, WM_SETTEXT, 0, 
            (LPARAM)TEXT("Registered for USB device notification...\n")); 

        break;

    case WM_SETFOCUS: 
        SetFocus(hEditWnd); 

        break;

    case WM_SIZE: 
        // Make the edit control the size of the window's client area. 
        MoveWindow(hEditWnd, 
                   0, 0,                  // starting x- and y-coordinates 
                   LOWORD(lParam),        // width of client area 
                   HIWORD(lParam),        // height of client area 
                   TRUE);                 // repaint window 

        break;

    case WM_DEVICECHANGE:
    {
        //
        // This is the actual message from the interface via Windows messaging.
        // This code includes some additional decoding for this particular device type
        // and some common validation checks.
        //
        // Note that not all devices utilize these optional parameters in the same
        // way. Refer to the extended information for your particular device type 
        // specified by your GUID.
        //
        PDEV_BROADCAST_DEVICEINTERFACE b = (PDEV_BROADCAST_DEVICEINTERFACE) lParam;
        (void)b;
        TCHAR strBuff[256];

        Main_OnDeviceChange(hEditWnd, wParam, lParam);

        // Output some messages to the window.
        switch (wParam)
        {
        case DBT_DEVICEARRIVAL:
            msgCount++;
            StringCchPrintf(
                strBuff, 256, 
                TEXT("Message %d: DBT_DEVICEARRIVAL\n"), msgCount);
            break;
        case DBT_DEVICEREMOVECOMPLETE:
            msgCount++;
            StringCchPrintf(
                strBuff, 256, 
                TEXT("Message %d: DBT_DEVICEREMOVECOMPLETE\n"), msgCount);
            break;
        case DBT_DEVNODES_CHANGED:
            msgCount++;
            StringCchPrintf(
                strBuff, 256, 
                TEXT("Message %d: DBT_DEVNODES_CHANGED\n"), msgCount);
            break;
        default:
            msgCount++;
            StringCchPrintf(
                strBuff, 256, 
                TEXT("Message %d: WM_DEVICECHANGE message received, value %d unhandled.\n"), 
                msgCount, wParam);
            break;
        }
        OutputMessage(hEditWnd, wParam, (LPARAM)strBuff);
    }
            break;
    case WM_CLOSE:
        if ( ! UnregisterDeviceNotification(hDeviceNotify) )
        {
           ErrorHandler(TEXT("UnregisterDeviceNotification")); 
        }
        DestroyWindow(hWnd);
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

    default:
        // Send all other messages on to the default windows handler.
        lRet = DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }

    return lRet;
}

#define WND_CLASS_NAME TEXT("SampleAppWindowClass")

//
// InitWindowClass
//
BOOL InitWindowClass(void)
// Routine Description:
//      Simple wrapper to initialize and register a window class.

// Parameters:
//     None

// Return Value:
//     TRUE on success, FALSE on failure.

// Note: 
//     wndClass.lpfnWndProc and wndClass.lpszClassName are the
//     important unique values used with CreateWindowEx and the
//     Windows message pump.
{
    WNDCLASSEX wndClass;

    wndClass.cbSize = sizeof(WNDCLASSEX);
    wndClass.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
    wndClass.hInstance = (HINSTANCE)(GetModuleHandle(0));
    wndClass.lpfnWndProc = (WNDPROC)(WinProcCallback);
    wndClass.cbClsExtra = 0;
    wndClass.cbWndExtra = 0;
    wndClass.hIcon = LoadIcon(0,IDI_APPLICATION);
    wndClass.hbrBackground = CreateSolidBrush(RGB(192,192,192));
    wndClass.hCursor = LoadCursor(0, IDC_ARROW);
    wndClass.lpszClassName = WND_CLASS_NAME;
    wndClass.lpszMenuName = NULL;
    wndClass.hIconSm = wndClass.hIcon;


    if ( ! RegisterClassEx(&wndClass) )
    {
        ErrorHandler(TEXT("RegisterClassEx"));
        return FALSE;
    }
    return TRUE;
}

//
// main
//

int __stdcall _tWinMain(
                      HINSTANCE hInstanceExe, 
                      HINSTANCE hInst, // should not reference this parameter
                      PTSTR lpstrCmdLine, 
                      int nCmdShow
                      )
{
//
// To enable a console project to compile this code, set
// Project->Properties->Linker->System->Subsystem: Windows.
//

    int nArgC = 0;
    PWSTR* ppArgV = CommandLineToArgvW(lpstrCmdLine, &nArgC);
    g_pszAppName = ppArgV[0];

    if ( ! InitWindowClass() )
    {
        // InitWindowClass displays any errors
        return -1;
    }

    // Main app window

    HWND hWnd = CreateWindowEx(
                    WS_EX_CLIENTEDGE | WS_EX_APPWINDOW,
                    WND_CLASS_NAME,
                    g_pszAppName,
                    WS_OVERLAPPEDWINDOW, // style
                    CW_USEDEFAULT, 0, 
                    640, 480,
                    NULL, NULL, 
                    hInstanceExe, 
                    NULL);

    if ( hWnd == NULL )
    {
        ErrorHandler(TEXT("CreateWindowEx: main appwindow hWnd"));
        return -1;
    }

    // Actually draw the window.

    ShowWindow(hWnd, SW_SHOWNORMAL);
    UpdateWindow(hWnd);

    // The message pump loops until the window is destroyed.

    MessagePump(hWnd);

    return 1;
}

//
// OutputMessage
//
void OutputMessage(
    HWND hOutWnd, 
    WPARAM wParam, 
    LPARAM lParam
)
// Routine Description:
//     Support routine.
//     Send text to the output window, scrolling if necessary.

// Parameters:
//     hOutWnd - Handle to the output window.
//     wParam  - Standard windows message code, not used.
//     lParam  - String message to send to the window.

// Return Value:
//     None

// Note:
//     This routine assumes the output window is an edit control
//     with vertical scrolling enabled.

//     This routine has no error checking.
{
    LRESULT   lResult;
    LONG      bufferLen;
    LONG      numLines;
    LONG      firstVis;

    // Make writable and turn off redraw.
    lResult = SendMessage(hOutWnd, EM_SETREADONLY, FALSE, 0L);
    lResult = SendMessage(hOutWnd, WM_SETREDRAW, FALSE, 0L);

    // Obtain current text length in the window.
    bufferLen = SendMessage (hOutWnd, WM_GETTEXTLENGTH, 0, 0L);
    numLines = SendMessage (hOutWnd, EM_GETLINECOUNT, 0, 0L);
    firstVis = SendMessage (hOutWnd, EM_GETFIRSTVISIBLELINE, 0, 0L);
    lResult = SendMessage (hOutWnd, EM_SETSEL, bufferLen, bufferLen);

    // Write the new text.
    lResult = SendMessage (hOutWnd, EM_REPLACESEL, 0, lParam);

    // See whether scrolling is necessary.
    if (numLines > (firstVis + 1))
    {
        int        lineLen = 0;
        int        lineCount = 0;
        int        charPos;

        // Find the last nonblank line.
        numLines--;
        while(!lineLen)
        {
            charPos = SendMessage(
                hOutWnd, EM_LINEINDEX, (WPARAM)numLines, 0L);
            lineLen = SendMessage(
                hOutWnd, EM_LINELENGTH, charPos, 0L);
            if(!lineLen)
                numLines--;
        }
        // Prevent negative value finding min.
        lineCount = numLines - firstVis;
        lineCount = (lineCount >= 0) ? lineCount : 0;

        // Scroll the window.
        lResult = SendMessage(
            hOutWnd, EM_LINESCROLL, 0, (LPARAM)lineCount);
    }

    // Done, make read-only and allow redraw.
    lResult = SendMessage(hOutWnd, WM_SETREDRAW, TRUE, 0L);
    lResult = SendMessage(hOutWnd, EM_SETREADONLY, TRUE, 0L);
}  

//
// ErrorHandler
//
void ErrorHandler(
   LPTSTR lpszFunction
) 
// Routine Description:
//     Support routine.
//     Retrieve the system error message for the last-error code
//     and pop a modal alert box with usable info.

// Parameters:
//     lpszFunction - String containing the function name where 
//     the error occurred plus any other relevant data you'd 
//     like to appear in the output. 

// Return Value:
//     None

// Note:
//     This routine is independent of the other windowing routines
//     in this application and can be used in a regular console
//     application without modification.
{ 

    LPVOID lpMsgBuf;
    LPVOID lpDisplayBuf;
    DWORD dw = GetLastError(); 

    FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER | 
        FORMAT_MESSAGE_FROM_SYSTEM |
        FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        dw,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPTSTR) &lpMsgBuf,
        0, NULL );

    // Display the error message and exit the process.

    lpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT, 
        (lstrlen((LPCTSTR)lpMsgBuf)
                  + lstrlen((LPCTSTR)lpszFunction)+40)
                  * sizeof(TCHAR)); 
    StringCchPrintf((LPTSTR)lpDisplayBuf, 
        LocalSize(lpDisplayBuf) / sizeof(TCHAR),
        TEXT("%s failed with error %d: %s"), 
        lpszFunction, dw, lpMsgBuf); 
    MessageBox(NULL, (LPCTSTR)lpDisplayBuf, g_pszAppName, MB_OK); 

    LocalFree(lpMsgBuf);
    LocalFree(lpDisplayBuf);
}

/*+@@fnc@@----------------------------------------------------------------*//*!
 \brief     Main_OnDeviceChange
 \date      Created  on Sun Sep 10 15:10:10 2017
 \date      Modified on Sun Sep 10 15:10:10 2017
\*//*-@@fnc@@----------------------------------------------------------------*/
void Main_OnDeviceChange(HWND hwnd, WPARAM wParam, LPARAM lParam)
{
    PDEV_BROADCAST_HDR lpdb = (PDEV_BROADCAST_HDR)lParam;
    TCHAR szMsg[80];

    switch (wParam)
    {
        case DBT_DEVICEARRIVAL:
            // Check whether a CD or DVD was inserted into a drive.
            if (lpdb->dbch_devicetype == DBT_DEVTYP_VOLUME)
            {
                PDEV_BROADCAST_VOLUME lpdbv = (PDEV_BROADCAST_VOLUME)lpdb;

                if (lpdbv->dbcv_flags & DBTF_MEDIA)
                {
                    StringCchPrintf(szMsg, sizeof(szMsg) / sizeof(szMsg[0]), TEXT("Drive %c: Media has arrived.\n"), FirstDriveFromMask(lpdbv->dbcv_unitmask));

                    //MessageBox( hwnd, szMsg, TEXT("WM_DEVICECHANGE"), MB_OK );
                }
                else
                {
                    StringCchPrintf(szMsg, sizeof(szMsg) / sizeof(szMsg[0]), TEXT("Assigned drive letter '%c'\n"), FirstDriveFromMask(lpdbv->dbcv_unitmask));
                }
                OutputMessage(hwnd, wParam, (LPARAM)szMsg);
            }
            break;

        case DBT_DEVICEREMOVECOMPLETE:
            // Check whether a CD or DVD was removed from a drive.
            if (lpdb->dbch_devicetype == DBT_DEVTYP_VOLUME)
            {
                PDEV_BROADCAST_VOLUME lpdbv = (PDEV_BROADCAST_VOLUME)lpdb;

                if (lpdbv->dbcv_flags & DBTF_MEDIA)
                {
                    StringCchPrintf(szMsg, sizeof(szMsg) / sizeof(szMsg[0]), TEXT("Drive %c: Media was removed.\n"), FirstDriveFromMask(lpdbv->dbcv_unitmask));

                    //MessageBox( hwnd, szMsg, TEXT("WM_DEVICECHANGE" ), MB_OK );
                }
                else
                {
                    StringCchPrintf(szMsg, sizeof(szMsg) / sizeof(szMsg[0]), TEXT("Disconnected drive '%c'\n"), FirstDriveFromMask(lpdbv->dbcv_unitmask));
                }
                OutputMessage(hwnd, wParam, (LPARAM)szMsg);
            }
            break;

        default:
            /*
               Process other WM_DEVICECHANGE notifications for other 
               devices or reasons.
             */
            ;
    }
}

/*------------------------------------------------------------------
   FirstDriveFromMask( unitmask )

   Description
     Finds the first valid drive letter from a mask of drive letters.
     The mask must be in the format bit 0 = A, bit 1 = B, bit 2 = C, 
     and so on. A valid drive letter is defined when the 
     corresponding bit is set to 1.

   Returns the first drive letter that was found.
--------------------------------------------------------------------*/

char FirstDriveFromMask( ULONG unitmask )
 {
  char i;

  for (i = 0; i < 26; ++i)
   {
    if (unitmask & 0x1)
      break;
    unitmask = unitmask >> 1;
   }

  return( i + 'A' );
}

Basically remove reinterpret_cast to C casts. I.e.:

wndClass.hInstance = reinterpret_cast<HINSTANCE>(GetModuleHandle(0));

to

wndClass.hInstance = (HINSTANCE)(GetModuleHandle(0));

And add unused parameters name in functions definition (that is not allowed in standard C). I.e. change from:

int __stdcall _tWinMain(
                      HINSTANCE hInstanceExe, 
                      HINSTANCE, // should not reference this parameter
                      PTSTR lpstrCmdLine, 
                      int nCmdShow
                      )

to:

int __stdcall _tWinMain(
                      HINSTANCE hInstanceExe, 
                      HINSTANCE hInst,  // you **must define this parameter** even if it's not referenced
                      PTSTR lpstrCmdLine, 
                      int nCmdShow
                      )

These simple modifications allow the use of almost all MS samples under plain-C compilers.

I have also added volume info.

To explain here in detail how the device notification framework works is just a waste of time. The MS documentation is complete and exhaustive, you can find all information on MSDN.

The translation I made give you the opportunity to study and test on your development environment in plain C, and this will allow to make experimentation.

Anyway the very basic essence is: the application (your program) registers itself with the notification server, that in turn, from now on until you unregister it, send all windows OS notification messages to your application. Each notification carries specific info data in specialized structures.

The full set of structure supplied with each notification (documented on MSDN) gives you indeep details on the type of change.