[英]Unable to retrieve data on a removable device using a Windows service in C++
我試圖檢測可移動設備的插入並使用NT服務檢索所述設備的驅動器號。 我已成功檢測到設備的插入和刪除,但無法設置DEV_BROADCAST_VOLUME
結構,這將允許我從卷中獲取驅動器號,GUID等。
case SERVICE_CONTROL_DEVICEEVENT:{
switch(evtype){
case DBT_DEVICEARRIVAL:{
DEV_BROADCAST_VOLUME *hdr = (DEV_BROADCAST_VOLUME*) evdata;
ofstream log ("C:\\log.txt", ios::app);
log << hdr->dbcv_devicetype;
log.close();
}
break;
上面的代碼片段編譯並正確運行,但是當我插入一個閃存驅動器時, hdr->dbcv_devicetype
日志值為55555
而DBT_DEVTYP_VOLUME
(這是一個USB驅動器)被定義為2
( hdr->dbcv_devicetype
應該等於DBT_DEVTYP_VOLUME
因為我插了一個閃存盤)。 由於某種原因, DBT_DEVTYP_VOLUME
沒有正確初始化,或者我正在做的其他事情是錯誤的。 我使用Windows 7與Visual Studio 2011 C ++。
嘗試這個:
PDEV_BROADCAST_HDR lpdb = (PDEV_BROADCAST_HDR)evdata;
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 );
}
}
/*------------------------------------------------------------------
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' );
}
代碼從檢測媒體插入或刪除中拉出
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.