How to eject USB flash disk?

[tovax]

Hi, all
I am developing a Qt application to transmit and receive files via USB, and read some posts in the forum, now I have detected the plug-in of the USB flash disk, but I don't know how to eject it, could you help me please?
Best regards!

Reference blog: https://blog.csdn.net/u014597198/article/details/72820737
PC: Windows7 64bits SP1
Qt: 5.12.4
QtCreator: 4.9.2

[Pl45m4]

@tovax

It's more a C++ problem.

It can be done with c++ (https://cboard.cprogramming.com/cplusplus-programming/172697-cplusplus-eject-usb-stick.html, assuming the code, that was posted there, works)

[jsulm]

@tovax I don't think you can do this with Qt. You will have to use native APIs or things like "umount" on Linux.

[Pl45m4]

@tovax

It's more a C++ problem.

It can be done with c++ (https://cboard.cprogramming.com/cplusplus-programming/172697-cplusplus-eject-usb-stick.html, assuming the code, that was posted there, works)

[tovax]

@jsulm Thank you very much! According to your suggestion, I found some useful blogs about my question.
(https://blog.csdn.net/qq2399431200/article/details/52336230)

Best regards!

[tovax]

@Pl45m4 Hi, Pl45m4, thank you very much for your reply, I will read this artical carefully!
All the best!

[tovax]

@jsulm @Pl45m4
I have been using the "usb-ejecter.exe" downloaded from the Internet before, and recently I found the code to eject the USB flash drive on win10, and it is currently running well.

bool usbDriveEject(const QString letter)
{
    QString device_path = QStringLiteral("%1:\\").arg(letter);
    QString error_string;
    const char* temp = "\\\\.\\";
    char device_path1[10] = { 0 };
    memcpy(device_path1, temp, strlen(temp));
    QByteArray dp = device_path.toLocal8Bit();
    device_path1[4] = dp.at(0);
    device_path1[5] = dp.at(1);
    HANDLE handleDevice = CreateFileA(device_path1, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, 0, nullptr);
    bool is_handle_invalid = (handleDevice == INVALID_HANDLE_VALUE);
    if (is_handle_invalid)
    {
        error_string = "Device is not connection to system!";
        qDebug() << GetLastError();
        return false;
    }
    // Do this in a loop until a timeout period has expired
    const int try_lock_volume_count = 3;
    int try_count = 0;
    for (; try_count < try_lock_volume_count; ++try_count)
    {
        DWORD dwBytesReturned;
        if (!DeviceIoControl(handleDevice, FSCTL_LOCK_VOLUME, nullptr, 0, nullptr, 0, &dwBytesReturned, nullptr))
        {
            qDebug() << "Device is using....." << try_count;
            break;
        }
        QThread::sleep(1);
    }
    if (try_count == try_lock_volume_count)
    {
        error_string = "Device is using, try again later";
        CloseHandle(handleDevice);
        return false;
    }
    DWORD  dwBytesReturned = 0;
    PREVENT_MEDIA_REMOVAL PMRBuffer;
    PMRBuffer.PreventMediaRemoval = FALSE;
    if (!DeviceIoControl(handleDevice, IOCTL_STORAGE_MEDIA_REMOVAL, &PMRBuffer, sizeof(PREVENT_MEDIA_REMOVAL), nullptr, 0, &dwBytesReturned, nullptr))
    {
        error_string = QStringLiteral("Unmount failed! error code:%1").arg(GetLastError());
        qDebug() << "DeviceIoControl IOCTL_STORAGE_MEDIA_REMOVAL failed:" << GetLastError();
        CloseHandle(handleDevice);
        return false;
    }
    long   bResult = 0;
    DWORD retu = 0;
    bResult = DeviceIoControl(handleDevice, IOCTL_STORAGE_EJECT_MEDIA, nullptr, 0, nullptr, 0, &retu, nullptr);
    if (!bResult)
    {
        error_string = QStringLiteral("Disconnect IGU failed! error code:%1").arg(GetLastError());
        CloseHandle(handleDevice);
        qDebug() << "Disconnect IGU IoControl failed error:" << GetLastError();
        return false;
    }
    CloseHandle(handleDevice);
    return true;
}