[partition] Rewrite new-partition API

The existing API required calling the one constructor with
specific pointers (nullptr for a partition-from-free-space)
followed by calling one of the initFrom*() functions. This
is fragile design.

Use tag-classes to distinguish create-from-free-space and
edit-another-freshly-created-partition cases, refactor
to merge the initFrom*() methods into the constructors
and factor out the shared UI creation.

Callers can now use the tag-class to distinguish. While
here, adjust both callers to use QPointer, avoiding some
very specific dialog-on-the-stack crash possibilities.

src/modules/partition/gui/CreatePartitionDialog.cpp

@@ -52,7 +52,6 @@ static QSet< FileSystem::Type > s_unmountableFS( { FileSystem::Unformatted,
 
 CreatePartitionDialog::CreatePartitionDialog( Device* device,
                                               PartitionNode* parentPartition,
-                                              Partition* partition,
                                               const QStringList& usedMountPoints,
                                               QWidget* parentWidget )
     : QDialog( parentWidget )
@@ -81,9 +80,6 @@ CreatePartitionDialog::CreatePartitionDialog( Device* device,
         m_ui->lvNameLineEdit->setValidator( validator );
     }
 
-    standardMountPoints( *( m_ui->mountPointComboBox ),
-                         partition ? PartitionInfo::mountPoint( partition ) : QString() );
-
     if ( device->partitionTable()->type() == PartitionTable::msdos
          || device->partitionTable()->type() == PartitionTable::msdos_sectorbased )
     {
@@ -132,13 +128,48 @@ CreatePartitionDialog::CreatePartitionDialog( Device* device,
     // Select a default
     m_ui->fsComboBox->setCurrentIndex( defaultFsIndex );
     updateMountPointUi();
+    checkMountPointSelection();
+}
 
+CreatePartitionDialog::CreatePartitionDialog( Device* device,
+                                              const FreeSpace& freeSpacePartition,
+                                              const QStringList& usedMountPoints,
+                                              QWidget* parentWidget )
+    : CreatePartitionDialog(device, freeSpacePartition.p->parent(), usedMountPoints, parentWidget )
+{
+    standardMountPoints( *( m_ui->mountPointComboBox ), QString() );
     setFlagList( *( m_ui->m_listFlags ),
                  static_cast< PartitionTable::Flags >( ~PartitionTable::Flags::Int( 0 ) ),
-                 partition ? PartitionInfo::flags( partition ) : PartitionTable::Flags() );
+                 PartitionTable::Flags() );
+    initPartResizerWidget( freeSpacePartition.p );
+}
 
-    // Checks the initial selection.
-    checkMountPointSelection();
+CreatePartitionDialog::CreatePartitionDialog( Device* device,
+                                              const FreshPartition& existingNewPartition,
+                                              const QStringList& usedMountPoints,
+                                              QWidget* parentWidget )
+    : CreatePartitionDialog(device, existingNewPartition.p->parent(), usedMountPoints, parentWidget )
+{
+    standardMountPoints( *( m_ui->mountPointComboBox ),
+                         PartitionInfo::mountPoint( existingNewPartition.p ) );
+    setFlagList( *( m_ui->m_listFlags ),
+                 static_cast< PartitionTable::Flags >( ~PartitionTable::Flags::Int( 0 ) ),
+                 PartitionInfo::flags( existingNewPartition.p ) );
+
+    const bool isExtended = existingNewPartition.p->roles().has( PartitionRole::Extended );
+    if ( isExtended )
+    {
+        cDebug() << "Editing extended partitions is not supported.";
+        return;
+    }
+
+    initPartResizerWidget( existingNewPartition.p );
+
+    FileSystem::Type fsType = existingNewPartition.p->fileSystem().type();
+    m_ui->fsComboBox->setCurrentText( FileSystem::nameForType( fsType ) );
+
+    setSelectedMountPoint( m_ui->mountPointComboBox, PartitionInfo::mountPoint( existingNewPartition.p ) );
+    updateMountPointUi();
 }
 
 CreatePartitionDialog::~CreatePartitionDialog() {}
@@ -288,34 +319,3 @@ CreatePartitionDialog::initPartResizerWidget( Partition* partition )
     m_partitionSizeController->setPartResizerWidget( m_ui->partResizerWidget );
     m_partitionSizeController->setSpinBox( m_ui->sizeSpinBox );
 }
-
-void
-CreatePartitionDialog::initFromFreeSpace( Partition* freeSpacePartition )
-{
-    initPartResizerWidget( freeSpacePartition );
-}
-
-void
-CreatePartitionDialog::initFromPartitionToCreate( Partition* partition )
-{
-    Q_ASSERT( partition );
-
-    bool isExtended = partition->roles().has( PartitionRole::Extended );
-    Q_ASSERT( !isExtended );
-    if ( isExtended )
-    {
-        cDebug() << "Editing extended partitions is not supported for now";
-        return;
-    }
-
-    initPartResizerWidget( partition );
-
-    // File System
-    FileSystem::Type fsType = partition->fileSystem().type();
-    m_ui->fsComboBox->setCurrentText( FileSystem::nameForType( fsType ) );
-
-    // Mount point
-    setSelectedMountPoint( m_ui->mountPointComboBox, PartitionInfo::mountPoint( partition ) );
-
-    updateMountPointUi();
-}

src/modules/partition/gui/CreatePartitionDialog.h

@@ -33,30 +33,41 @@ class Ui_CreatePartitionDialog;
 class CreatePartitionDialog : public QDialog
 {
     Q_OBJECT
+
+private:
+    /** @brief Delegated constructor
+     *
+     * This does all the shared UI setup.
+     */
+    CreatePartitionDialog( Device* device,
+                              PartitionNode* parentPartition,
+                              const QStringList& usedMountPoints,
+                              QWidget* parentWidget );
+
 public:
-    /**
-     * @brief Dialog for editing a new partition.
+    struct FreeSpace { Partition* p; };
+    struct FreshPartition { Partition* p; };
+
+    /** @brief Dialog for editing a new partition based on free space.
      *
-     * For the (unlikely) case that a newly created partition is being re-edited,
-     * pass a pointer to that @p partition, otherwise pass nullptr.
+     * Creating from free space makes a wholly new partition with
+     * no flags set at all.
      */
     CreatePartitionDialog( Device* device,
-                           PartitionNode* parentPartition,
-                           Partition* partition,
+                           const FreeSpace& freeSpacePartition,
                            const QStringList& usedMountPoints,
                            QWidget* parentWidget = nullptr );
-    ~CreatePartitionDialog() override;
-
-    /**
-     * Must be called when user wants to create a partition in
-     * freeSpacePartition.
+    /** @brief Dialog for editing a newly-created partition.
+     *
+     * A partition previously newly created (e.g. via this dialog
+     * and the constructor above) can be re-edited.
      */
-    void initFromFreeSpace( Partition* freeSpacePartition );
+    CreatePartitionDialog( Device* device,
+                           const FreshPartition& existingNewPartition,
+                           const QStringList& usedMountPoints,
+                           QWidget* parentWidget = nullptr );
+    ~CreatePartitionDialog() override;
 
-    /**
-     * Must be called when user wants to edit a to-be-created partition.
-     */
-    void initFromPartitionToCreate( Partition* partition );
     Partition* getNewlyCreatedPartition();
 
     PartitionTable::Flags newFlags() const;

src/modules/partition/gui/PartitionPage.cpp

@@ -391,13 +391,14 @@ PartitionPage::onCreateClicked()
         return;
     }
 
-    CreatePartitionDialog dlg( model->device(), partition->parent(), nullptr, getCurrentUsedMountpoints(), this );
-    dlg.initFromFreeSpace( partition );
-    if ( dlg.exec() == QDialog::Accepted )
+    QPointer< CreatePartitionDialog > dlg = new
+    CreatePartitionDialog ( model->device(), CreatePartitionDialog::FreeSpace{ partition }, getCurrentUsedMountpoints(), this );
+    if ( dlg->exec() == QDialog::Accepted )
     {
-        Partition* newPart = dlg.getNewlyCreatedPartition();
-        m_core->createPartition( model->device(), newPart, dlg.newFlags() );
+        Partition* newPart = dlg->getNewlyCreatedPartition();
+        m_core->createPartition( model->device(), newPart, dlg->newFlags() );
     }
+    delete dlg;
 }
 
 void
@@ -492,8 +493,7 @@ PartitionPage::updatePartitionToCreate( Device* device, Partition* partition )
     mountPoints.removeOne( PartitionInfo::mountPoint( partition ) );
 
     QPointer< CreatePartitionDialog > dlg
-        = new CreatePartitionDialog( device, partition->parent(), partition, mountPoints, this );
-    dlg->initFromPartitionToCreate( partition );
+        = new CreatePartitionDialog( device, CreatePartitionDialog::FreshPartition{ partition }, mountPoints, this );
     if ( dlg->exec() == QDialog::Accepted )
     {
         Partition* newPartition = dlg->getNewlyCreatedPartition();