[libcalamares] Add a RAII mounter

- mount on creation, unmount on destruction

src/libcalamares/partition/Mount.cpp

@@ -82,6 +82,24 @@ unmount( const QString& path, const QStringList& options )
     return r.getExitCode();
 }
 
+TemporaryMount::TemporaryMount( const QString& devicePath,
+                                const QString& mountPoint,
+                                const QString& filesystemName,
+                                const QString& options )
+    : m_devicePath( devicePath )
+{
+    int r = mount( m_devicePath, mountPoint, filesystemName, options );
+    m_valid = r == 0;
+}
+
+TemporaryMount::~TemporaryMount()
+{
+    if ( m_valid )
+    {
+        unmount( m_devicePath );
+    }
+}
+
 
 }  // namespace Partition
 }  // namespace CalamaresUtils

src/libcalamares/partition/Mount.h

@@ -53,6 +53,23 @@ DLLEXPORT int mount( const QString& devicePath,
  * @returns the program's exit codeor special codes like mount().
  */
 DLLEXPORT int unmount( const QString& path, const QStringList& options = QStringList() );
+
+DLLEXPORT class TemporaryMount
+{
+public:
+    TemporaryMount( const QString& devicePath,
+                    const QString& mountPoint,
+                    const QString& filesystemName = QString(),
+                    const QString& options = QString() );
+    ~TemporaryMount();
+
+    bool isValid() const { return m_valid; }
+
+private:
+    QString m_devicePath;
+    bool m_valid;
+};
+
 }  // namespace Partition
 }  // namespace CalamaresUtils