[libcalamares] Add isEditable() check

This adds support for checking whether a field is editable;
Config objects should reject changes if the field is not
editable. There is an "unlock" setting to override the
check, although this is currently always locked.

src/libcalamares/modulesystem/Config.cpp

@@ -60,5 +60,20 @@ Config::loadPresets( const QVariantMap& configurationMap, const QStringList& rec
         = std::make_unique< Presets >( CalamaresUtils::getSubMap( configurationMap, key, bogus ), recognizedKeys );
 }
 
+bool
+Config::isEditable( const QString& fieldName ) const
+{
+    if ( m_unlocked )
+    {
+        return true;
+    }
+    if ( d && d->m_presets )
+    {
+        return d->m_presets->isEditable( fieldName );
+    }
+    return true;
+}
+
+
 }  // namespace ModuleSystem
 }  // namespace Calamares

src/libcalamares/modulesystem/Config.h

@@ -34,6 +34,7 @@ namespace ModuleSystem
  */
 class DLLEXPORT Config : public QObject
 {
+    Q_OBJECT
 public:
     Config( QObject* parent = nullptr );
     ~Config() override;
@@ -46,6 +47,16 @@ public:
      */
     virtual void setConfigurationMap( const QVariantMap& ) = 0;
 
+public Q_SLOTS:
+    /** @brief Checks if a @p fieldName is editable according to presets
+     *
+     * If the field is named as a preset, **and** the field is set
+     * to not-editable, returns @c false. Otherwise, return @c true.
+     * Calling this with an unknown field (one for which no presets
+     * are accepted) will print a warning and return @c true.
+     */
+    bool isEditable( const QString& fieldName ) const;
+
 protected:
     void loadPresets( const QVariantMap& configurationMap );
     void loadPresets( const QVariantMap& configurationMap, const QStringList& recognizedKeys );
@@ -53,6 +64,7 @@ protected:
 private:
     class Private;
     std::unique_ptr< Private > d;
+    bool m_unlocked = false;
 };
 }  // namespace ModuleSystem
 }  // namespace Calamares

src/libcalamares/modulesystem/Preset.cpp

@@ -33,7 +33,11 @@ loadPresets( Calamares::ModuleSystem::Presets& preset,
     }
 }
 
-Calamares::ModuleSystem::Presets::Presets( const QVariantMap& configurationMap )
+namespace Calamares
+{
+namespace ModuleSystem
+{
+Presets::Presets( const QVariantMap& configurationMap )
 
 
 {
@@ -41,9 +45,26 @@ Calamares::ModuleSystem::Presets::Presets( const QVariantMap& configurationMap )
     loadPresets( *this, configurationMap, []( const QString& ) { return true; } );
 }
 
-Calamares::ModuleSystem::Presets::Presets( const QVariantMap& configurationMap, const QStringList& recognizedKeys )
+Presets::Presets( const QVariantMap& configurationMap, const QStringList& recognizedKeys )
 {
     reserve( recognizedKeys.size() );
     loadPresets(
         *this, configurationMap, [&recognizedKeys]( const QString& s ) { return recognizedKeys.contains( s ); } );
 }
+
+bool
+Presets::isEditable( const QString& fieldName ) const
+{
+    for ( const auto& p : *this )
+    {
+        if ( p.fieldName == fieldName )
+        {
+            return p.editable;
+        }
+    }
+    return true;
+}
+
+
+}  // namespace ModuleSystem
+}  // namespace Calamares

src/libcalamares/modulesystem/Preset.h

@@ -48,8 +48,26 @@ struct PresetField
 class Presets : public QVector< PresetField >
 {
 public:
+    /** @brief Reads preset entries from the map
+     *
+     * The map's keys are used as field name, and each value entry
+     * should specify an initial value and whether the entry is editable.
+     * Fields are editable by default.
+     */
     explicit Presets( const QVariantMap& configurationMap );
+    /** @brief Reads preset entries from the @p configurationMap
+     *
+     * As above, but only field names that occur in @p recognizedKeys
+     * are kept; others are discarded.
+     */
     Presets( const QVariantMap& configurationMap, const QStringList& recognizedKeys );
+
+    /** @brief Is the given @p fieldName editable?
+     *
+     * Fields are editable by default, so if there is no explicit setting,
+     * returns @c true.
+     */
+    bool isEditable( const QString& fieldName ) const;
 };
 }  // namespace ModuleSystem
 }  // namespace Calamares