[gui] add explicit prune setter

This makes it possible to enable pruning after the OptionsModel has been initialized and reset.

src/qt/bitcoin.cpp

@@ -282,6 +282,10 @@ void BitcoinApplication::parameterSetup()
     m_node.initParameterInteraction();
 }
 
+void BitcoinApplication::SetPrune(bool prune, bool force) {
+     optionsModel->SetPrune(prune, force);
+}
+
 void BitcoinApplication::requestInitialize()
 {
     qDebug() << __func__ << ": Requesting initialize";

src/qt/bitcoin.h

@@ -67,6 +67,8 @@ public:
     void parameterSetup();
     /// Create options model
     void createOptionsModel(bool resetSettings);
+    /// Update prune value
+    void SetPrune(bool prune, bool force = false);
     /// Create main window
     void createWindow(const NetworkStyle *networkStyle);
     /// Create splash screen

src/qt/optionsmodel.cpp

@@ -92,11 +92,7 @@ void OptionsModel::Init(bool resetSettings)
         settings.setValue("bPrune", false);
     if (!settings.contains("nPruneSize"))
         settings.setValue("nPruneSize", 2);
-    // Convert prune size from GB to MiB:
-    const uint64_t nPruneSizeMiB = (settings.value("nPruneSize").toInt() * GB_BYTES) >> 20;
-    if (!m_node.softSetArg("-prune", settings.value("bPrune").toBool() ? std::to_string(nPruneSizeMiB) : "0")) {
-        addOverriddenOption("-prune");
-    }
+    SetPrune(settings.value("bPrune").toBool());
 
     if (!settings.contains("nDatabaseCache"))
         settings.setValue("nDatabaseCache", (qint64)nDefaultDbCache);
@@ -240,6 +236,22 @@ static const QString GetDefaultProxyAddress()
     return QString("%1:%2").arg(DEFAULT_GUI_PROXY_HOST).arg(DEFAULT_GUI_PROXY_PORT);
 }
 
+void OptionsModel::SetPrune(bool prune, bool force)
+{
+    QSettings settings;
+    settings.setValue("bPrune", prune);
+    // Convert prune size from GB to MiB:
+    const uint64_t nPruneSizeMiB = (settings.value("nPruneSize").toInt() * GB_BYTES) >> 20;
+    std::string prune_val = prune ? std::to_string(nPruneSizeMiB) : "0";
+    if (force) {
+        m_node.forceSetArg("-prune", prune_val);
+        return;
+    }
+    if (!m_node.softSetArg("-prune", prune_val)) {
+        addOverriddenOption("-prune");
+    }
+}
+
 // read QSettings values and return them
 QVariant OptionsModel::data(const QModelIndex & index, int role) const
 {

src/qt/optionsmodel.h

@@ -77,6 +77,9 @@ public:
     bool getCoinControlFeatures() const { return fCoinControlFeatures; }
     const QString& getOverriddenByCommandLine() { return strOverriddenByCommandLine; }
 
+    /* Explicit setters */
+    void SetPrune(bool prune, bool force = false);
+
     /* Restart flag helper */
     void setRestartRequired(bool fRequired);
     bool isRestartRequired() const;