fix: sync engine readonly folder file deletion

This is for #7797 and #10099

Signed-off-by: Markus Goetz <markus@woboq.com>
Assisted-by: ClaudeCode:claude-opus-4-8

Author: guruz

src/gui/tray/usermodel.cpp

@@ -1390,6 +1390,11 @@ void User::processCompletedSyncItem(const Folder *folder, const SyncFileItemPtr
                 activity._links = {buttonActivityLink};
             }
             _activityModel->addErrorToActivityList(activity, ActivityListModel::ErrorType::SyncError);
+        } else if (!item->_errorString.isEmpty()) {
+            // The item was ignored for a concrete reason (e.g. it lives in a read-only
+            // folder and cannot be uploaded). Surface it passively in the Not-synced list
+            // so the user can see why it did not sync.
+            _activityModel->addErrorToActivityList(activity, ActivityListModel::ErrorType::SyncError);
         }
     }
 }

src/libsync/discovery.cpp

@@ -1637,6 +1637,14 @@ void ProcessDirectoryJob::processFileAnalyzeLocalInfo(
             return;
         }
 
+        // The move target is in a read-only folder so it can't be uploaded, but its data is safe
+        // at the source (restored below). Emitting remnantReadOnlyFolderDiscovered() schedules this
+        // local copy for deletion at the end of the sync, removing the duplicate. A genuinely new
+        // local file never reaches this move branch and is kept by checkPermissions (#7797/#10099).
+        if (!localEntry.isVirtualFile && item->_instruction == CSYNC_INSTRUCTION_IGNORE) {
+            emit _discoveryData->remnantReadOnlyFolderDiscovered(item);
+        }
+
         // Here we know the new location can't be uploaded: must prevent the source delete.
         // Two cases: either the source item was already processed or not.
         auto wasDeletedOnClient = _discoveryData->findAndCancelDeletedJob(originalPath);
@@ -2017,13 +2025,15 @@ bool ProcessDirectoryJob::checkPermissions(const OCC::SyncFileItemPtr &item)
             qCWarning(lcDisco) << "checkForPermission: Not allowed because you don't have permission to add subfolders to that folder:" << item->_file;
             item->_instruction = CSYNC_INSTRUCTION_IGNORE;
             item->_errorString = tr("Not allowed because you don't have permission to add subfolders to that folder");
-            emit _discoveryData->remnantReadOnlyFolderDiscovered(item);
+            // Do NOT schedule the new local folder for deletion: it may contain data the user just
+            // created and that exists nowhere else. (see read-only folder regression, issues #7797/#10099).
             return false;
         } else if (!item->isDirectory() && !perms.hasPermission(RemotePermissions::CanAddFile)) {
             qCWarning(lcDisco) << "checkForPermission: Not allowed because you don't have permission to add files in that folder:" << item->_file;
             item->_instruction = CSYNC_INSTRUCTION_IGNORE;
             item->_errorString = tr("Not allowed because you don't have permission to add files in that folder");
-            emit _discoveryData->remnantReadOnlyFolderDiscovered(item);
+            // Do NOT schedule the new local file for deletion: it may be data the user just created
+            // and that exists nowhere else. (see read-only folder regression, issues #7797/#10099).
             return false;
         }
         break;

test/CMakeLists.txt

@@ -78,9 +78,7 @@ nextcloud_add_test(Blacklist)
 nextcloud_add_test(LocalDiscovery)
 nextcloud_add_test(RemoteDiscovery)
 
-if (NOT APPLE)
-    nextcloud_add_test(Permissions)
-endif()
+nextcloud_add_test(Permissions)
 
 nextcloud_add_test(SelectiveSync)
 nextcloud_add_test(DatabaseError)

test/testpermissions.cpp

@@ -297,9 +297,12 @@ private slots:
         currentLocalState = fakeFolder.currentLocalState();
 
         //6.
-        // The file should not exist on the remote, and not be there
-        QVERIFY(!currentLocalState.find("readonlyDirectory_PERM_MG_/newFile_PERM_GWDNV_.data"));
+        // The file cannot be uploaded to the read-only folder, but it MUST be kept locally:
+        // it is local-only data and silently deleting it would lose it (issues #7797/#10099).
+        QVERIFY(currentLocalState.find("readonlyDirectory_PERM_MG_/newFile_PERM_GWDNV_.data"));
         QVERIFY(!fakeFolder.currentRemoteState().find("readonlyDirectory_PERM_MG_/newFile_PERM_GWDNV_.data"));
+        // Remove the kept local-only file so the following sections can compare local and remote.
+        removeReadOnly("readonlyDirectory_PERM_MG_/newFile_PERM_GWDNV_.data");
         // Both side should still be the same
         QCOMPARE(fakeFolder.currentLocalState(), fakeFolder.currentRemoteState());
 
@@ -379,7 +382,8 @@ private slots:
         QVERIFY(currentLocalState.find("readonlyDirectory_PERM_MG_/subdir_PERM_CKG_" ));
         // including contents
         QVERIFY(currentLocalState.find("readonlyDirectory_PERM_MG_/subdir_PERM_CKG_/subsubdir_PERM_CKDNVG_/normalFile_PERM_GWVND_.data" ));
-        // new no longer exists
+        // new no longer exists: it was a move of an existing (server-side) item into a read-only
+        // folder, so the local copy is cleaned up while its data is restored at the source above.
         QVERIFY(!currentLocalState.find("readonlyDirectory_PERM_MG_/newname_PERM_CK_/subsubdir_PERM_CKDNVG_/normalFile_PERM_GWVND_.data" ));
         // but is not on server: should have been locally removed
         QVERIFY(!currentLocalState.find("readonlyDirectory_PERM_MG_/newname_PERM_CK_"));