Function isHeadless

src/shared/shared.cpp:210–241

TODO: check if this works with Wayland

// TODO: check if this works with Wayland
bool isHeadless() {
    bool isHeadless = true;

    // not really clean to abuse env vars as "global storage", but hey, it works
    if (getenv("_FORCE_HEADLESS")) {
        return true;
    }

    QProcess proc;
    proc.setProgram("xhost");
    proc.setStandardOutputFile(QProcess::nullDevice());
    proc.setStandardErrorFile(QProcess::nullDevice());

    proc.start();
    proc.waitForFinished();

    switch (proc.exitCode()) {
        case 255: {
            // program not found, using fallback method
            isHeadless = (getenv("DISPLAY") == nullptr);
            break;
        }
        case 0:
        case 1:
            isHeadless = proc.exitCode() == 1;
            break;
        default:
            throw std::runtime_error("Headless detection failed: unexpected exit code from xhost");
    }

    return isHeadless;
}

// avoids code duplication, and works for both graphical and non-graphical environments
void displayMessageBox(const QString& title, const QString& message, const QMessageBox::Icon icon) {