Vfs: Switch on/off only when sync isn't running #6936

Avoids some situations that might cause data loss.

src/gui/accountsettings.cpp

@@ -457,7 +457,8 @@ void AccountSettings::slotCustomContextMenuRequested(const QPoint &pos)
 
     if (Theme::instance()->showVirtualFilesOption()
         && !folder->supportsVirtualFiles()
-        && bestAvailableVfsMode() != Vfs::Off) {
+        && bestAvailableVfsMode() != Vfs::Off
+        && !folder->isVfsOnOffSwitchPending()) {
         ac = menu->addAction(tr("Enable virtual file support (experimental)..."));
         connect(ac, &QAction::triggered, this, &AccountSettings::slotEnableVfsCurrentFolder);
     }
@@ -648,6 +649,12 @@ void AccountSettings::slotEnableVfsCurrentFolder()
         if (!enable || !folder)
             return;
 
+        // It is unsafe to switch on vfs while a sync is running - wait if necessary.
+        auto connection = std::make_shared<QMetaObject::Connection>();
+        auto switchVfsOn = [folder, connection, this]() {
+            if (*connection)
+                QObject::disconnect(*connection);
+
             qCInfo(lcAccountSettings) << "Enabling vfs support for folder" << folder->path();
 
             // Wipe selective sync blacklist
@@ -660,6 +667,7 @@ void AccountSettings::slotEnableVfsCurrentFolder()
 
             // Change the folder vfs mode and load the plugin
             folder->setSupportsVirtualFiles(true);
+            folder->setVfsOnOffSwitchPending(false);
 
             // Wipe pin states to be sure
             folder->journalDb()->wipePinStateForPathAndBelow("");
@@ -667,8 +675,17 @@ void AccountSettings::slotEnableVfsCurrentFolder()
 
             FolderMan::instance()->scheduleFolder(folder);
 
-        // Update the ui: no selective sync, vfs indicator; size changed
             _ui->_folderList->doItemsLayout();
+        };
+
+        if (folder->isSyncRunning()) {
+            *connection = connect(folder, &Folder::syncFinished, this, switchVfsOn);
+            folder->setVfsOnOffSwitchPending(true);
+            folder->slotTerminateSync();
+            _ui->_folderList->doItemsLayout();
+        } else {
+            switchVfsOn();
+        }
     });
 }
 
@@ -687,7 +704,9 @@ void AccountSettings::slotDisableVfsCurrentFolder()
            "are currently marked as 'available online only' will be downloaded."
            "\n\n"
            "The only advantage of disabling virtual file support is that the selective sync feature "
-           "will become available again."));
+           "will become available again."
+           "\n\n"
+           "This action will abort any currently running synchronization."));
     msgBox->addButton(tr("Disable support"), QMessageBox::AcceptRole);
     msgBox->addButton(tr("Cancel"), QMessageBox::RejectRole);
     connect(msgBox, &QMessageBox::finished, msgBox, [this, msgBox, folder](int result) {
@@ -695,10 +714,17 @@ void AccountSettings::slotDisableVfsCurrentFolder()
         if (result != QMessageBox::AcceptRole || !folder)
             return;
 
+        // It is unsafe to switch off vfs while a sync is running - wait if necessary.
+        auto connection = std::make_shared<QMetaObject::Connection>();
+        auto switchVfsOff = [folder, connection, this]() {
+            if (*connection)
+                QObject::disconnect(*connection);
+
             qCInfo(lcAccountSettings) << "Disabling vfs support for folder" << folder->path();
 
             // Also wipes virtual files, schedules remote discovery
             folder->setSupportsVirtualFiles(false);
+            folder->setVfsOnOffSwitchPending(false);
 
             // Wipe pin states and selective sync db
             folder->journalDb()->wipePinStateForPathAndBelow("");
@@ -707,8 +733,17 @@ void AccountSettings::slotDisableVfsCurrentFolder()
 
             FolderMan::instance()->scheduleFolder(folder);
 
-        // Update the ui: no selective sync, vfs indicator; size changed
             _ui->_folderList->doItemsLayout();
+        };
+
+        if (folder->isSyncRunning()) {
+            *connection = connect(folder, &Folder::syncFinished, this, switchVfsOff);
+            folder->setVfsOnOffSwitchPending(true);
+            folder->slotTerminateSync();
+            _ui->_folderList->doItemsLayout();
+        } else {
+            switchVfsOff();
+        }
     });
     msgBox->open();
 }

src/gui/wizard/owncloudwizard.cpp

@@ -341,6 +341,8 @@ void OwncloudWizard::askExperimentalVirtualFilesFeature(const std::function<void
                "When a file is opened its contents will be downloaded automatically. "
                "Alternatively files can be downloaded manually by using their context menu."
                "\n\n"
+               "Switching to this mode will abort any currently running synchronization."
+               "\n\n"
                "This is a new, experimental mode. If you decide to use it, please report any "
                "issues that come up."));
     } else {
@@ -352,6 +354,8 @@ void OwncloudWizard::askExperimentalVirtualFilesFeature(const std::function<void
                "Instead, a tiny \"%1\" file will be created for each file that exists on the server. "
                "The contents can be downloaded by running these files or by using their context menu."
                "\n\n"
+               "Switching to this mode will abort any currently running synchronization."
+               "\n\n"
                "This is a new, experimental mode. If you decide to use it, please report any "
                "issues that come up.")
                 .arg(APPLICATION_DOTVIRTUALFILE_SUFFIX));