[libcalamares] Stub of saveYaml

- This belongs alongside loadYaml, so place it in libcalamares
 - Doesn't actually save anything yet (it isn't used yet)

src/libcalamares/GlobalStorage.cpp

@@ -21,6 +21,7 @@
 #include "JobQueue.h"
 
 #include "utils/Logger.h"
+#include "utils/YamlUtils.h"
 
 #include <QFile>
 #include <QJsonDocument>
@@ -110,6 +111,23 @@ GlobalStorage::save(const QString& filename)
 }
 
 
+bool
+GlobalStorage::saveYaml( const QString& filename )
+{
+    return CalamaresUtils::saveYaml( filename, m );
+}
+
+bool
+GlobalStorage::loadYaml( const QString& filename )
+{
+    bool ok = false;
+    auto gs = CalamaresUtils::loadYaml( filename, &ok );
+    if ( ok )
+        m = gs;
+    return ok;
+}
+
+
 } // namespace Calamares
 
 #ifdef WITH_PYTHON

src/libcalamares/utils/YamlUtils.cpp

@@ -203,4 +203,38 @@ loadYaml(const QString& filename, bool* ok)
     return QVariantMap();
 }
 
+/// @brief Convenience function writes @p indent times four spaces
+static void
+writeIndent( QFile& f, int indent )
+{
+    while ( indent > 0 )
+        f.write( "    " );
+}
+
+/// @brief Recursive helper to dump @p map to file
+static bool
+dumpYaml( QFile& f, const QVariantMap& map, int indent )
+{
+    for ( auto it = map.cbegin(); it != map.cend(); ++it )
+    {
+        writeIndent( f, indent );
+        f.write( it.key().toUtf8() );
+        f.write( "\n" );
+    }
+    return true;
+}
+
+bool
+saveYaml( const QString& filename, const QVariantMap& map )
+{
+    QFile f( filename );
+    if ( !f.open( QFile::WriteOnly ) )
+        return false;
+
+    f.write( "# YAML dump\n---\n" );
+    return dumpYaml( f, map, 0 );
+}
+
+
+
 }  // namespace

src/libcalamares/utils/YamlUtils.h

@@ -51,6 +51,9 @@ QVariant yamlScalarToVariant( const YAML::Node& scalarNode );
 QVariant yamlSequenceToVariant( const YAML::Node& sequenceNode );
 QVariant yamlMapToVariant( const YAML::Node& mapNode );
 
+/// @brief Save a @p map to @p filename as YAML
+bool saveYaml( const QString& filename, const QVariantMap& map );
+
 /**
  * Given an exception from the YAML parser library, explain
  * what is going on in terms of the data passed to the parser.