[libcalamares] Slightly more memory-safe

Use unique_ptr to ensure Private is always deleted.

SEE #1758

src/libcalamares/partition/Mount.cpp

@@ -92,7 +92,7 @@ struct TemporaryMount::Private
 
 
 TemporaryMount::TemporaryMount( const QString& devicePath, const QString& filesystemName, const QString& options )
-    : m_d( new Private )
+    : m_d( std::make_unique<Private>() )
 {
     m_d->m_devicePath = devicePath;
     m_d->m_mountDir.setAutoRemove( false );
@@ -100,8 +100,7 @@ TemporaryMount::TemporaryMount( const QString& devicePath, const QString& filesy
     if ( r )
     {
         cWarning() << "Mount of" << devicePath << "on" << m_d->m_mountDir.path() << "failed, code" << r;
-        delete m_d;
-        m_d = nullptr;
+        m_d.reset();
     }
 }
 
@@ -115,8 +114,6 @@ TemporaryMount::~TemporaryMount()
             cWarning() << "UnMount of temporary" << m_d->m_devicePath << "on" << m_d->m_mountDir.path()
                        << "failed, code" << r;
         }
-        delete m_d;
-        m_d = nullptr;
     }
 }
 

src/libcalamares/partition/Mount.h

@@ -17,6 +17,8 @@
 #include <QString>
 #include <QStringList>
 
+#include <memory>
+
 namespace CalamaresUtils
 {
 namespace Partition
@@ -58,12 +60,12 @@ public:
     TemporaryMount& operator=( const TemporaryMount& ) = delete;
     ~TemporaryMount();
 
-    bool isValid() const { return m_d; }
+    bool isValid() const { return bool( m_d ); }
     QString path() const;
 
 private:
     struct Private;
-    Private* m_d = nullptr;
+    std::unique_ptr< Private > m_d;
 };
 
 }  // namespace Partition