QNI: Add a convenience method for loading the default plugin

We have some official plugins, we may as well treat them as default
and give a convenient function which loads those.

Change-Id: I6251c77ac042b795bcf24b86e510e960ee4bab54
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

src/network/kernel/qnetworkinformation.cpp

@@ -603,12 +603,63 @@ QNetworkInformation::Features QNetworkInformation::supportedFeatures() const
     return d_func()->backend->featuresSupported();
 }
 
+/*!
+    \since 6.3
+
+    Attempts to load the platform-default backend.
+
+    This platform-to-plugin mapping is as follows:
+
+    \table
+    \header
+        \li Platform
+        \li Plugin-name
+    \row
+        \li Windows
+        \li networklistmanager
+    \row
+        \li Apple (macOS/iOS)
+        \li scnetworkreachability
+    \row
+        \li Android
+        \li android
+    \row
+        \li Linux
+        \li networkmanager
+    \endtable
+
+    This function is provided for convenience where the default for a given
+    platform is good enough. If you are not using the default plugins you must
+    use one of the other load() overloads.
+
+    Returns \c true if it managed to load the backend or if it was already
+    loaded. Returns \c false otherwise.
+
+    \sa instance
+*/
+bool QNetworkInformation::load()
+{
+    int index = -1;
+#ifdef Q_OS_WIN
+    index = QNetworkInformationBackend::PluginNamesWindowsIndex;
+#elif defined(Q_OS_DARWIN)
+    index = QNetworkInformationBackend::PluginNamesAppleIndex;
+#elif defined(Q_OS_ANDROID)
+    index = QNetworkInformationBackend::PluginNamesAndroidIndex;
+#elif defined(Q_OS_LINUX)
+    index = QNetworkInformationBackend::PluginNamesLinuxIndex;
+#endif
+    if (index == -1)
+        return false;
+    return load(QNetworkInformationBackend::PluginNames[index]);
+}
+
 /*!
     Attempts to load a backend whose name matches \a backend
     (case insensitively).
 
     Returns \c true if it managed to load the requested backend or
-    if it was already loaded. Returns \c false otherwise
+    if it was already loaded. Returns \c false otherwise.
 
     \sa instance
 */
@@ -622,7 +673,7 @@ bool QNetworkInformation::load(QStringView backend)
     Load a backend which supports \a features.
 
     Returns \c true if it managed to load the requested backend or
-    if it was already loaded. Returns \c false otherwise
+    if it was already loaded. Returns \c false otherwise.
 
     \sa instance
 */

src/network/kernel/qnetworkinformation.h

@@ -96,6 +96,7 @@ public:
     bool supports(Features features) const;
     Features supportedFeatures() const;
 
+    static bool load();
     static bool load(QStringView backend);
     static bool load(Features features);
     static QStringList availableBackends();

src/network/kernel/qnetworkinformation_p.h

@@ -67,6 +67,17 @@ class Q_NETWORK_EXPORT QNetworkInformationBackend : public QObject
     using TransportMedium = QNetworkInformation::TransportMedium;
 
 public:
+    static inline const char16_t PluginNames[4][22] = {
+        { u"networklistmanager" },
+        { u"scnetworkreachability" },
+        { u"android" },
+        { u"networkmanager" },
+    };
+    static constexpr int PluginNamesWindowsIndex = 0;
+    static constexpr int PluginNamesAppleIndex = 1;
+    static constexpr int PluginNamesAndroidIndex = 2;
+    static constexpr int PluginNamesLinuxIndex = 3;
+
     QNetworkInformationBackend() = default;
     ~QNetworkInformationBackend() override;
 

src/plugins/networkinformation/android/qandroidnetworkinformationbackend.cpp

@@ -47,7 +47,10 @@ QT_BEGIN_NAMESPACE
 Q_DECLARE_LOGGING_CATEGORY(lcNetInfoAndroid)
 Q_LOGGING_CATEGORY(lcNetInfoAndroid, "qt.network.info.android");
 
-static const QString backendName = QStringLiteral("android");
+static QString backendName() {
+    return QString::fromUtf16(QNetworkInformationBackend::PluginNames
+                                      [QNetworkInformationBackend::PluginNamesAndroidIndex]);
+}
 
 class QAndroidNetworkInformationBackend : public QNetworkInformationBackend
 {
@@ -56,7 +59,7 @@ public:
     QAndroidNetworkInformationBackend();
     ~QAndroidNetworkInformationBackend() { m_valid = false; }
 
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         return featuresSupportedStatic();
@@ -88,7 +91,7 @@ class QAndroidNetworkInformationBackendFactory : public QNetworkInformationBacke
 public:
     QAndroidNetworkInformationBackendFactory() = default;
     ~QAndroidNetworkInformationBackendFactory() = default;
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         return QAndroidNetworkInformationBackend::featuresSupportedStatic();

src/plugins/networkinformation/networklistmanager/qnetworklistmanagernetworkinformationbackend.cpp

@@ -50,7 +50,11 @@ QT_BEGIN_NAMESPACE
 // Declared in qnetworklistmanagerevents.h
 Q_LOGGING_CATEGORY(lcNetInfoNLM, "qt.network.info.netlistmanager");
 
-static const QString backendName = QStringLiteral("networklistmanager");
+static QString backendName()
+{
+    return QString::fromUtf16(QNetworkInformationBackend::PluginNames
+                                      [QNetworkInformationBackend::PluginNamesWindowsIndex]);
+}
 
 namespace {
 bool testCONNECTIVITY(NLM_CONNECTIVITY connectivity, NLM_CONNECTIVITY flag)
@@ -90,7 +94,7 @@ public:
     QNetworkListManagerNetworkInformationBackend();
     ~QNetworkListManagerNetworkInformationBackend();
 
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         return featuresSupportedStatic();
@@ -130,7 +134,7 @@ class QNetworkListManagerNetworkInformationBackendFactory : public QNetworkInfor
 public:
     QNetworkListManagerNetworkInformationBackendFactory() = default;
     ~QNetworkListManagerNetworkInformationBackendFactory() = default;
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         return QNetworkListManagerNetworkInformationBackend::featuresSupportedStatic();

src/plugins/networkinformation/networkmanager/qnetworkmanagernetworkinformationbackend.cpp

@@ -120,7 +120,11 @@ transportMediumFromDeviceType(QNetworkManagerInterface::NMDeviceType type)
 }
 }
 
-static QString backendName = QStringLiteral("networkmanager");
+static QString backendName()
+{
+    return QString::fromUtf16(QNetworkInformationBackend::PluginNames
+                                      [QNetworkInformationBackend::PluginNamesLinuxIndex]);
+}
 
 class QNetworkManagerNetworkInformationBackend : public QNetworkInformationBackend
 {
@@ -129,7 +133,7 @@ public:
     QNetworkManagerNetworkInformationBackend();
     ~QNetworkManagerNetworkInformationBackend() = default;
 
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         if (!isValid())
@@ -160,7 +164,7 @@ class QNetworkManagerNetworkInformationBackendFactory : public QNetworkInformati
 public:
     QNetworkManagerNetworkInformationBackendFactory() = default;
     ~QNetworkManagerNetworkInformationBackendFactory() = default;
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         if (!QNetworkManagerInterfaceBase::networkManagerAvailable())

src/plugins/networkinformation/scnetworkreachability/qscnetworkreachabilitynetworkinformationbackend.mm

@@ -48,8 +48,11 @@ QT_BEGIN_NAMESPACE
 Q_DECLARE_LOGGING_CATEGORY(lcNetInfoSCR)
 Q_LOGGING_CATEGORY(lcNetInfoSCR, "qt.network.info.scnetworkreachability");
 
-
+static QString backendName()
-static QString backendName = QStringLiteral("scnetworkreachability");
+{
+    return QString::fromUtf16(QNetworkInformationBackend::PluginNames
+                                      [QNetworkInformationBackend::PluginNamesAppleIndex]);
+}
 
 class QSCNetworkReachabilityNetworkInformationBackend : public QNetworkInformationBackend
 {
@@ -58,7 +61,7 @@ public:
     QSCNetworkReachabilityNetworkInformationBackend();
     ~QSCNetworkReachabilityNetworkInformationBackend();
 
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         return featuresSupportedStatic();
@@ -87,7 +90,7 @@ class QSCNetworkReachabilityNetworkInformationBackendFactory : public QNetworkIn
 public:
     QSCNetworkReachabilityNetworkInformationBackendFactory() = default;
     ~QSCNetworkReachabilityNetworkInformationBackendFactory() = default;
-    QString name() const override { return backendName; }
+    QString name() const override { return backendName(); }
     QNetworkInformation::Features featuresSupported() const override
     {
         return QSCNetworkReachabilityNetworkInformationBackend::featuresSupportedStatic();

tests/manual/qnetworkinformation/tst_qnetworkinformation.cpp

@@ -46,9 +46,8 @@ int main(int argc, char **argv)
     QCoreApplication app(argc, argv);
 #endif
 
-    if (!QNetworkInformation::load(QNetworkInformation::Feature::Reachability
+    // Use the platform-default:
-                                   | QNetworkInformation::Feature::CaptivePortal
+    if (!QNetworkInformation::load()) {
-                                   | QNetworkInformation::Feature::TransportMedium)) {
         qWarning("Failed to load any backend");
         qDebug() << "Backends available:" << QNetworkInformation::availableBackends().join(", ");
         return -1;