我正在尝试检测可移动设备的插入并使用 NT 服务检索所述设备的驱动器号。我已成功检测到设备的插入和移除,但无法设置一个 DEV_BROADCAST_VOLUME
结构,该结构允许我从卷中获取驱动器号、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;
上面的代码片段可以正确编译和运行,但是当我插入闪存驱动器时,hdr->dbcv_devicetype
记录为 55555
和 DBT_DEVTYP_VOLUME
(这是 USB 驱动器)被定义为 2
(hdr->dbcv_devicetype
应该等于 DBT_DEVTYP_VOLUME
因为我插入了一个闪存驾驶)。由于某种原因,DBT_DEVTYP_VOLUME
未正确初始化,或者我正在做的其他事情是错误的。我正在使用 Windows 7 和 Visual Studio 2011 C++。
最佳答案
试试这个:
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' );
}
关于c++ - 无法使用 C++ 中的 Windows 服务检索可移动设备上的数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8724890/