Remove USB Device Safely

实现的功能：Remove USB Device Safely

1.获取设备Handle

根据卷的驱动器类型和DOS设备名，使用Windows API枚举所有磁盘，包括软盘、光盘，或者其他设备。

//---------------------------------------------------------------------- 
// returns the device instance handle of a storage volume or 0 on error 
//---------------------------------------------------------------------- 
DEVINST GetDrivesDevInstByDeviceNumber(long DeviceNumber, UINT DriveType, char* szDosDeviceName) 
{ 
    bool IsFloppy = (strstr(szDosDeviceName, "\\Floppy") != NULL);

    GUID* guid;

    switch (DriveType) { 
    case DRIVE_REMOVABLE: 
        if ( IsFloppy ) { 
            guid = (GUID*)&GUID_DEVINTERFACE_FLOPPY; 
        } else { 
            guid = (GUID*)&GUID_DEVINTERFACE_DISK; 
        } 
        break; 
    case DRIVE_FIXED: 
        guid = (GUID*)&GUID_DEVINTERFACE_DISK; 
        break; 
    case DRIVE_CDROM: 
        guid = (GUID*)&GUID_DEVINTERFACE_CDROM; 
        break; 
    default: 
        return 0; 
    }

    // 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 
    DWORD dwIndex = 0; 
    long res;

    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);

    while ( true )    { 
        res = SetupDiEnumDeviceInterfaces(hDevInfo, NULL, guid, dwIndex, &spdid); 
        if ( !res ) { 
            break; 
        }

        dwSize = 0; 
        SetupDiGetDeviceInterfaceDetail(hDevInfo, &spdid, NULL, 0, &dwSize, NULL); // check the buffer size

        if ( dwSize!=0 && dwSize<=sizeof(Buf) ) {

            pspdidd->cbSize = sizeof(*pspdidd); // 5 Bytes!

            ZeroMemory(&spdd, sizeof(spdd)); 
            spdd.cbSize = sizeof(spdd);

            long res = SetupDiGetDeviceInterfaceDetail(hDevInfo, &spdid, pspdidd, dwSize, &dwSize, &spdd); 
            if ( res ) {

                // in case you are interested in the USB serial number: 
                // the device id string contains the serial number if the device has one, 
                // otherwise a generated id that contains the '&' char... 
                /* 
                DEVINST DevInstParent = 0; 
                CM_Get_Parent(&DevInstParent, spdd.DevInst, 0); 
                char szDeviceIdString[MAX_PATH]; 
                CM_Get_Device_ID(DevInstParent, szDeviceIdString, MAX_PATH, 0); 
                printf("DeviceId=%s\n", szDeviceIdString); 
                */

                // open the disk or cdrom or floppy 
                HANDLE hDrive = CreateFile(pspdidd->DevicePath, 0, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL); 
                if ( hDrive != INVALID_HANDLE_VALUE ) { 
                    // get its device number 
                    STORAGE_DEVICE_NUMBER sdn; 
                    DWORD dwBytesReturned = 0; 
                    res = DeviceIoControl(hDrive, IOCTL_STORAGE_GET_DEVICE_NUMBER, NULL, 0, &sdn, sizeof(sdn), &dwBytesReturned, NULL); 
                    if ( res ) { 
                        if ( DeviceNumber == (long)sdn.DeviceNumber ) {  // match the given device number with the one of the current device 
                            CloseHandle(hDrive); 
                            SetupDiDestroyDeviceInfoList(hDevInfo); 
                            return spdd.DevInst; 
                        } 
                    } 
                    CloseHandle(hDrive); 
                } 
            } 
        } 
        dwIndex++; 
    }

    SetupDiDestroyDeviceInfoList(hDevInfo);

    return 0; 
}

2.Remove Usb Device的主程序

本例中usb的盘符为G盘

    char DriveLetter = 'G'; 
    DriveLetter &= ~0x20; // uppercase

    if ( DriveLetter < 'A' || DriveLetter > 'Z' ) { 
        return 1; 
    }

    char szRootPath[] = "X:\\";   // "X:\"  -> for GetDriveType 
    szRootPath[0] = DriveLetter;

    char szDevicePath[] = "X:";   // "X:"   -> for QueryDosDevice 
    szDevicePath[0] = DriveLetter;

    char szVolumeAccessPath[] = "\\\\.\\X:";   // "\\.\X:"  -> to open the volume 
    szVolumeAccessPath[4] = DriveLetter;

    long DeviceNumber = -1;

2.1 open the storage volume

    HANDLE hVolume = CreateFile(szVolumeAccessPath, 0, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, NULL, NULL); 
    if (hVolume == INVALID_HANDLE_VALUE) { 
        return 1; 
    }

2.2 get the volume's device number

    STORAGE_DEVICE_NUMBER sdn; 
    DWORD dwBytesReturned = 0; 
    long res = DeviceIoControl(hVolume, IOCTL_STORAGE_GET_DEVICE_NUMBER, NULL, 0, &sdn, sizeof(sdn), &dwBytesReturned, NULL); 
    if ( res ) { 
        DeviceNumber = sdn.DeviceNumber; 
    } 
    CloseHandle(hVolume);

    if ( DeviceNumber == -1 ) { 
        return 1; 
    }

2.3 get the drive type

    UINT DriveType = GetDriveType(szRootPath);

2.4 get the dos device name

    char szDosDeviceName[MAX_PATH]; 
    res = QueryDosDevice(szDevicePath, szDosDeviceName, MAX_PATH); 
    if ( !res ) { 
        return 1; 
    }

2.5 get the device instance handle

    DEVINST DevInst = GetDrivesDevInstByDeviceNumber(DeviceNumber, DriveType, szDosDeviceName);

    if ( DevInst == 0 ) { 
        return 1; 
    }

    PNP_VETO_TYPE VetoType = PNP_VetoTypeUnknown; 
    WCHAR VetoNameW[MAX_PATH]; 
    VetoNameW[0] = 0; 
    bool bSuccess = false;

2.6 get drives's parent

    DEVINST DevInstParent = 0; 
    res = CM_Get_Parent(&DevInstParent, DevInst, 0);

    for ( long tries=1; tries<=3; tries++ ) { // sometimes we need try more than one times...

        VetoNameW[0] = 0;

        // CM_Query_And_Remove_SubTree doesn't work for restricted users 
        //res = CM_Query_And_Remove_SubTreeW(DevInstParent, &VetoType, VetoNameW, MAX_PATH, CM_REMOVE_NO_RESTART); // CM_Query_And_Remove_SubTreeA is not implemented under W2K! 
        //res = CM_Query_And_Remove_SubTreeW(DevInstParent, NULL, NULL, 0, CM_REMOVE_NO_RESTART);  // with messagebox (W2K, Vista) or balloon (XP) 
        res = CM_Request_Device_EjectW(DevInstParent, &VetoType, VetoNameW, MAX_PATH, 0); 
        //res = CM_Request_Device_EjectW(DevInstParent, NULL, NULL, 0, 0); // with messagebox (W2K, Vista) or balloon (XP)

        bSuccess = (res==CR_SUCCESS && VetoType==PNP_VetoTypeUnknown); 
        if ( bSuccess )  { 
            break; 
        }

        Sleep(500); // required to give the next tries a chance! 
    }

转自:http://www.cnblogs.com/xuesong/archive/2010/08/10/1796678.html