Revert "DragAndDropHelper::updateDropAction: use StatJob for remote URLs"

This reverts commit dc149ec5e5.

This prevents a crash. One issue identified is that the commit that
I am reverting here accesses a QDropEvent at a moment in time in
which it might have already been deleted. We cannot check if it
exists by that time because we do not control its lifetime and it
is not a QObject.

src/dolphintabwidget.cpp

@@ -9,6 +9,7 @@
 #include "dolphin_generalsettings.h"
 #include "dolphintabbar.h"
 #include "dolphinviewcontainer.h"
+#include "views/draganddrophelper.h"
 
 #include <KAcceleratorManager>
 #include <KConfigGroup>
@@ -23,7 +24,6 @@
 
 DolphinTabWidget::DolphinTabWidget(DolphinNavigatorsWidgetAction *navigatorsWidget, QWidget *parent)
     : QTabWidget(parent)
-    , m_dragAndDropHelper{this}
     , m_lastViewedTab(nullptr)
     , m_navigatorsWidget{navigatorsWidget}
 {
@@ -394,7 +394,7 @@ void DolphinTabWidget::tabDragMoveEvent(int index, QDragMoveEvent *event)
 {
     if (index >= 0) {
         DolphinView *view = tabPageAt(index)->activeViewContainer()->view();
-        m_dragAndDropHelper.updateDropAction(event, view->url());
+        DragAndDropHelper::updateDropAction(event, view->url());
     }
 }
 

src/dolphintabwidget.h

@@ -9,7 +9,6 @@
 
 #include "dolphinnavigatorswidgetaction.h"
 #include "dolphintabpage.h"
-#include "views/draganddrophelper.h"
 
 #include <QTabWidget>
 #include <QUrl>
@@ -277,8 +276,6 @@ private:
      */
     const std::optional<const ViewIndex> viewShowingItem(const QUrl &item) const;
 
-    DragAndDropHelper m_dragAndDropHelper;
-
 private:
     QPointer<DolphinTabPage> m_lastViewedTab;
     QPointer<DolphinNavigatorsWidgetAction> m_navigatorsWidget;

src/panels/places/placespanel.cpp

@@ -15,6 +15,7 @@
 #include "dolphin_placespanelsettings.h"
 #include "dolphinplacesmodelsingleton.h"
 #include "settings/dolphinsettingsdialog.h"
+#include "views/draganddrophelper.h"
 
 #include <KFilePlacesModel>
 #include <KIO/DropJob>
@@ -31,7 +32,6 @@
 
 PlacesPanel::PlacesPanel(QWidget *parent)
     : KFilePlacesView(parent)
-    , m_dragAndDropHelper(this)
 {
     setDropOnPlaceEnabled(true);
     connect(this, &PlacesPanel::urlsDropped, this, &PlacesPanel::slotUrlsDropped);
@@ -161,7 +161,7 @@ void PlacesPanel::dragMoveEvent(QDragMoveEvent *event)
             if (!url.isValid() || !KProtocolManager::supportsWriting(url)) {
                 event->setDropAction(Qt::IgnoreAction);
             } else {
-                m_dragAndDropHelper.updateDropAction(event, url);
+                DragAndDropHelper::updateDropAction(event, url);
             }
         }
     }

src/panels/places/placespanel.h

@@ -10,7 +10,6 @@
 #define PLACESPANEL_H
 
 #include "panels/panel.h"
-#include "views/draganddrophelper.h"
 
 #include <KFilePlacesView>
 #include <QUrl>
@@ -79,8 +78,6 @@ private:
     QAction *m_configureTrashAction;
     QAction *m_openInSplitView;
     QAction *m_lockPanelsAction;
-
-    DragAndDropHelper m_dragAndDropHelper;
 };
 
 #endif // PLACESPANEL_H

src/views/draganddrophelper.cpp

@@ -73,85 +73,20 @@ bool DragAndDropHelper::supportsDropping(const KFileItem &destItem)
     return (destItem.isDir() && destItem.isWritable()) || destItem.isDesktopFile();
 }
 
-DragAndDropHelper::DragAndDropHelper(QObject *parent)
-    : QObject(parent)
-{
-    m_destItemCacheInvalidationTimer.setSingleShot(true);
-    m_destItemCacheInvalidationTimer.setInterval(30000);
-    connect(&m_destItemCacheInvalidationTimer, &QTimer::timeout, this, [this]() {
-        m_destItemCache = KFileItem();
-    });
-}
-
 void DragAndDropHelper::updateDropAction(QDropEvent *event, const QUrl &destUrl)
 {
-    auto processEvent = [this](QDropEvent *event) {
-        if (supportsDropping(m_destItemCache)) {
-            event->setDropAction(event->proposedAction());
-            event->accept();
-        } else {
-            event->setDropAction(Qt::IgnoreAction);
-            event->ignore();
-        }
-    };
-
-    m_lastUndecidedEvent = nullptr;
-
     if (urlListMatchesUrl(event->mimeData()->urls(), destUrl)) {
         event->setDropAction(Qt::IgnoreAction);
         event->ignore();
-        return;
     }
-
+    KFileItem item(destUrl);
-    if (destUrl == m_destItemCache.url()) {
+    if (!item.isLocalFile() || supportsDropping(item)) {
-        // We already received events for this URL, and already have the
+        event->setDropAction(event->proposedAction());
-        // stat result cached because:
+        event->accept();
-        // 1. it's a local file, and we already called KFileItem(destUrl)
+    } else {
-        // 2. it's a remote file, and StatJob finished
+        event->setDropAction(Qt::IgnoreAction);
-        processEvent(event);
+        event->ignore();
-        return;
     }
-
-    if (m_statJob) {
-        if (destUrl == m_statJobUrl) {
-            // We already received events for this URL. Still waiting for
-            // the stat result. StatJob will process the event when it finishes.
-            m_lastUndecidedEvent = event;
-            return;
-        }
-
-        // We are waiting for the stat result of a different URL. Cancel.
-        m_statJob->kill();
-        m_statJob = nullptr;
-        m_statJobUrl.clear();
-    }
-
-    if (destUrl.isLocalFile()) {
-        // New local URL. KFileItem will stat on demand.
-        m_destItemCache = KFileItem(destUrl);
-        m_destItemCacheInvalidationTimer.start();
-        processEvent(event);
-        return;
-    }
-
-    // New remote URL. Start a StatJob and process the event when it finishes.
-    m_lastUndecidedEvent = event;
-    m_statJob = KIO::stat(destUrl, KIO::StatJob::SourceSide, KIO::StatDetail::StatBasic, KIO::JobFlag::HideProgressInfo);
-    m_statJobUrl = destUrl;
-    connect(m_statJob, &KIO::StatJob::result, this, [this, processEvent](KJob *job) {
-        KIO::StatJob *statJob = static_cast<KIO::StatJob *>(job);
-
-        m_destItemCache = KFileItem(statJob->statResult(), m_statJobUrl);
-        m_destItemCacheInvalidationTimer.start();
-
-        if (m_lastUndecidedEvent) {
-            processEvent(m_lastUndecidedEvent);
-            m_lastUndecidedEvent = nullptr;
-        }
-
-        m_statJob = nullptr;
-        m_statJobUrl.clear();
-    });
 }
 
 void DragAndDropHelper::clearUrlListMatchesUrlCache()

src/views/draganddrophelper.h

@@ -11,11 +11,9 @@
 #include "dolphin_export.h"
 
 #include <KFileItem>
-#include <KIO/StatJob>
 
 #include <QList>
 #include <QString>
-#include <QTimer>
 #include <QUrl>
 
 class QDropEvent;
@@ -26,7 +24,7 @@ namespace KIO
 class DropJob;
 }
 
-class DOLPHIN_EXPORT DragAndDropHelper : public QObject
+class DOLPHIN_EXPORT DragAndDropHelper
 {
 public:
     /**
@@ -53,6 +51,16 @@ public:
      */
     static bool supportsDropping(const KFileItem &destItem);
 
+    /**
+     * Updates the drop action according to whether the destination supports dropping.
+     * If supportsDropping(destUrl), set dropAction = proposedAction. Otherwise, set
+     * dropAction = Qt::IgnoreAction.
+     *
+     * @param event     Drop event.
+     * @param destUrl   Destination URL.
+     */
+    static void updateDropAction(QDropEvent *event, const QUrl &destUrl);
+
     /**
      * @return True if destUrl is contained in the urls parameter.
      */
@@ -76,55 +84,11 @@ public:
      */
     static void clearUrlListMatchesUrlCache();
 
-    DragAndDropHelper(QObject *parent);
-
-    /**
-     * Updates the drop action according to whether the destination supports dropping.
-     * If supportsDropping(destUrl), set dropAction = proposedAction. Otherwise, set
-     * dropAction = Qt::IgnoreAction.
-     *
-     * @param event     Drop event.
-     * @param destUrl   Destination URL.
-     */
-    void updateDropAction(QDropEvent *event, const QUrl &destUrl);
-
 private:
     /**
      * Stores the results of the expensive checks made in urlListMatchesUrl.
      */
     static QHash<QUrl, bool> m_urlListMatchesUrlCache;
-
-    /**
-     * When updateDropAction() is called with a remote URL, we create a StatJob to
-     * check if the destination is a directory or a desktop file. We cache the result
-     * here to avoid doing the stat again on subsequent calls to updateDropAction().
-     */
-    KFileItem m_destItemCache;
-
-    /**
-     * Only keep the cache for 30 seconds, because the stat of the destUrl might change.
-     */
-    QTimer m_destItemCacheInvalidationTimer;
-
-    /**
-     * A StatJob on-fly to fill the cache for a remote URL. We shouldn't create more
-     * than one StatJob at a time, so we keep a pointer to the current one.
-     */
-    KIO::StatJob *m_statJob = nullptr;
-
-    /**
-     * The URL for which the StatJob is running.
-     * Note: We can't use m_statJob->url() because StatJob might resolve the URL to be
-     *       different from what we passed into stat(). E.g. "mtp:<bus-name>" is resolved
-     *       to "mtp:<phone name>"
-     */
-    QUrl m_statJobUrl;
-
-    /**
-     * The last event we received in updateDropAction(), but can't react to yet,
-     * because a StatJob is on-fly.
-     */
-    QDropEvent *m_lastUndecidedEvent = nullptr;
 };
 
 #endif