[libcalamares] Move TemporaryDir into TemporaryMount

- Only one user of TemporaryMount, and we should distinguish
   "regular" temp mounts from temp mounts with a hand-picked
   mount point.

src/libcalamares/partition/Mount.cpp

@@ -24,6 +24,7 @@
 #include "utils/Logger.h"
 
 #include <QDir>
+#include <QTemporaryDir>
 
 namespace CalamaresUtils
 {
@@ -90,24 +91,41 @@ 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 )
+struct TemporaryMount::Private
 {
-    int r = mount( m_devicePath, mountPoint, filesystemName, options );
-    m_valid = r == 0;
+    QString m_devicePath;
+    QTemporaryDir m_mountDir;
+};
+
+
+TemporaryMount::TemporaryMount( const QString& devicePath, const QString& filesystemName, const QString& options )
+    : m_d( new Private )
+{
+    m_d->m_devicePath = devicePath;
+    m_d->m_mountDir.setAutoRemove( false );
+    int r = mount( devicePath, m_d->m_mountDir.path(), filesystemName, options );
+    if ( !r )
+    {
+        delete m_d;
+        m_d = nullptr;
+    }
 }
 
 TemporaryMount::~TemporaryMount()
 {
-    if ( m_valid )
+    if ( m_d )
     {
-        unmount( m_devicePath, { "-R" } );
+        unmount( m_d->m_devicePath, { "-R" } );
+        delete m_d;
+        m_d = nullptr;
     }
 }
 
+QString
+TemporaryMount::path() const
+{
+    return m_d ? m_d->m_mountDir.path() : QString();
+}
 
 }  // namespace Partition
 }  // namespace CalamaresUtils

src/libcalamares/partition/Mount.h

@@ -60,16 +60,18 @@ class DLLEXPORT TemporaryMount
 {
 public:
     TemporaryMount( const QString& devicePath,
-                    const QString& mountPoint,
                     const QString& filesystemName = QString(),
                     const QString& options = QString() );
+    TemporaryMount( const TemporaryMount& ) = delete;
+    TemporaryMount& operator=( const TemporaryMount& ) = delete;
     ~TemporaryMount();
 
-    bool isValid() const { return m_valid; }
+    bool isValid() const { return m_d; }
+    QString path() const;
 
 private:
-    QString m_devicePath;
-    bool m_valid;
+    struct Private;
+    Private* m_d = nullptr;
 };
 
 }  // namespace Partition

src/modules/partition/core/PartUtils.cpp

@@ -246,13 +246,11 @@ lookForFstabEntries( const QString& partitionPath )
         << "for fstab (fs=" << r.getOutput() << ')';
 
     FstabEntryList fstabEntries;
-    QTemporaryDir mountsDir;
-    mountsDir.setAutoRemove( false );
 
-    CalamaresUtils::Partition::TemporaryMount mount( partitionPath, mountsDir.path(), QString(), mountOptions.join(',') );
+    CalamaresUtils::Partition::TemporaryMount mount( partitionPath, QString(), mountOptions.join(',') );
     if ( mount.isValid() )
     {
-        QFile fstabFile( mountsDir.path() + "/etc/fstab" );
+        QFile fstabFile( mount.path() + "/etc/fstab" );
 
         cDebug() << Logger::SubEntry << "reading" << fstabFile.fileName();