好吧，我想通了。 Luke 链接到的 CodeProject 文章展示了如何将驱动器号与设备接口相匹配，该接口已完成一半，因此我将+1 该答案，但它并不能解决整个问题。
我需要弄清楚如何找到我的 USB 设备的设备实例，并找到一种将其与设备接口相匹配的方法。 CM_Locate_DevNode() 和 CM_Get_Child() 函数是其中的关键。最后我可以使用 IOCTL 来弹出设备。
我正在处理的设备是 USB CD-ROM 驱动器，这就是我将设备类型硬编码为 CDROM 的原因。我不敢相信需要多少代码来完成我认为相当简单的任务（我引用我的客户 2 小时来编写此代码，我花了四天时间才弄清楚这一切！）。这是最终的工作代码，希望能够使你们中的一个人免于经历与我一样的地狱：
#include <SetupAPI.h>
#include <cfgmgr32.h>
#include <winioctl.h>
// Finds the device interface for the CDROM drive with the given interface number.
DEVINST GetDrivesDevInstByDeviceNumber(long DeviceNumber)
{
const GUID *guid = &GUID_DEVINTERFACE_CDROM;
// Get device interface info set handle
// for all devices attached to system
HDEVINFO hDevInfo = SetupDiGetClassDevs(guid, NULL, NULL, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
if(hDevInfo == INVALID_HANDLE_VALUE)
return 0;
// Retrieve a context structure for a device interface of a device information set.
BYTE buf[1024];
PSP_DEVICE_INTERFACE_DETAIL_DATA pspdidd = (PSP_DEVICE_INTERFACE_DETAIL_DATA)buf;
SP_DEVICE_INTERFACE_DATA spdid;
SP_DEVINFO_DATA spdd;
DWORD dwSize;
spdid.cbSize = sizeof(spdid);
// Iterate through all the interfaces and try to match one based on
// the device number.
for(DWORD i = 0; SetupDiEnumDeviceInterfaces(hDevInfo, NULL,guid, i, &spdid); i++)
{
// Get the device path.
dwSize = 0;
SetupDiGetDeviceInterfaceDetail(hDevInfo, &spdid, NULL, 0, &dwSize, NULL);
if(dwSize == 0 || dwSize > sizeof(buf))
continue;
pspdidd->cbSize = sizeof(*pspdidd);
ZeroMemory((PVOID)&spdd, sizeof(spdd));
spdd.cbSize = sizeof(spdd);
if(!SetupDiGetDeviceInterfaceDetail(hDevInfo, &spdid, pspdidd,
dwSize, &dwSize, &spdd))
continue;
// Open the device.
HANDLE hDrive = CreateFile(pspdidd->DevicePath,0,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL, OPEN_EXISTING, 0, NULL);
if(hDrive == INVALID_HANDLE_VALUE)
continue;
// Get the device number.
STORAGE_DEVICE_NUMBER sdn;
dwSize = 0;
if(DeviceIoControl(hDrive,
IOCTL_STORAGE_GET_DEVICE_NUMBER,
NULL, 0, &sdn, sizeof(sdn),
&dwSize, NULL))
{
// Does it match?
if(DeviceNumber == (long)sdn.DeviceNumber)
{
CloseHandle(hDrive);
SetupDiDestroyDeviceInfoList(hDevInfo);
return spdd.DevInst;
}
}
CloseHandle(hDrive);
}
SetupDiDestroyDeviceInfoList(hDevInfo);
return 0;
}
// Returns true if the given device instance belongs to the USB device with the given VID and PID.
bool matchDevInstToUsbDevice(DEVINST device, DWORD vid, DWORD pid)
{
// This is the string we will be searching for in the device harware IDs.
TCHAR hwid[64];
_stprintf(hwid, _T("VID_%04X&PID_%04X"), vid, pid);
// Get a list of hardware IDs for all USB devices.
ULONG ulLen;
CM_Get_Device_ID_List_Size(&ulLen, NULL, CM_GETIDLIST_FILTER_NONE);
TCHAR *pszBuffer = new TCHAR[ulLen];
CM_Get_Device_ID_List(NULL, pszBuffer, ulLen, CM_GETIDLIST_FILTER_NONE);
// Iterate through the list looking for our ID.
for(LPTSTR pszDeviceID = pszBuffer; *pszDeviceID; pszDeviceID += _tcslen(pszDeviceID) + 1)
{
// Some versions of Windows have the string in upper case and other versions have it
// in lower case so just make it all upper.
for(int i = 0; pszDeviceID[i]; i++)
pszDeviceID[i] = toupper(pszDeviceID[i]);
if(_tcsstr(pszDeviceID, hwid))
{
// Found the device, now we want the grandchild device, which is the "generic volume"
DEVINST MSDInst = 0;
if(CR_SUCCESS == CM_Locate_DevNode(&MSDInst, pszDeviceID, CM_LOCATE_DEVNODE_NORMAL))
{
DEVINST DiskDriveInst = 0;
if(CR_SUCCESS == CM_Get_Child(&DiskDriveInst, MSDInst, 0))
{
// Now compare the grandchild node against the given device instance.
if(device == DiskDriveInst)
return true;
}
}
}
}
return false;
}
// Eject the given drive.
void ejectDrive(TCHAR driveletter)
{
TCHAR devicepath[16];
_tcscpy(devicepath, _T("\\\\.\\?:"));
devicepath[4] = driveletter;
DWORD dwRet = 0;
HANDLE hVol = CreateFile(devicepath, GENERIC_READ, FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
if(hVol == INVALID_HANDLE_VALUE)
return;
if(!DeviceIoControl(hVol, FSCTL_LOCK_VOLUME, 0, 0, 0, 0, &dwRet, 0))
return;
if(!DeviceIoControl(hVol, FSCTL_DISMOUNT_VOLUME, 0, 0, 0, 0, &dwRet, 0))
return;
DeviceIoControl(hVol, IOCTL_STORAGE_EJECT_MEDIA, 0, 0, 0, 0, &dwRet, 0);
CloseHandle(hVol);
}
// Find a USB device by it's Vendor and Product IDs. When found, eject it.
void usbEjectDevice(unsigned vid, unsigned pid)
{
TCHAR devicepath[8];
_tcscpy(devicepath, _T("\\\\.\\?:"));
TCHAR drivepath[4];
_tcscpy(drivepath, _T("?:\\"));
// Iterate through every drive letter and check if it is our device.
for(TCHAR driveletter = _T('A'); driveletter <= _T('Z'); driveletter++)
{
// We are only interested in CDROM drives.
drivepath[0] = driveletter;
if(DRIVE_CDROM != GetDriveType(drivepath))
continue;
// Get the "storage device number" for the current drive.
long DeviceNumber = -1;
devicepath[4] = driveletter;
HANDLE hVolume = CreateFile(devicepath, 0, FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL, OPEN_EXISTING, 0, NULL);
if(INVALID_HANDLE_VALUE == hVolume)
continue;
STORAGE_DEVICE_NUMBER sdn;
DWORD dwBytesReturned = 0;
if(DeviceIoControl(hVolume, IOCTL_STORAGE_GET_DEVICE_NUMBER,
NULL, 0, &sdn, sizeof(sdn), &dwBytesReturned, NULL))
DeviceNumber = sdn.DeviceNumber;
CloseHandle(hVolume);
if(DeviceNumber < 0)
continue;
// Use the data we have collected so far on our drive to find a device instance.
DEVINST DevInst = GetDrivesDevInstByDeviceNumber(DeviceNumber);
// If the device instance corresponds to the USB device we are looking for, eject it.
if(DevInst)
{
if(matchDevInstToUsbDevice(DevInst, vid, pid))
ejectDrive(driveletter);
}
}
}
