Warn if we encounter an unsupported configuration

Author: TheOneRing

src/gui/folderman.cpp

@@ -36,8 +36,16 @@
 #include <QSet>
 #include <QNetworkProxy>
 
-static const char versionC[] = "version";
-static const int maxFoldersVersion = 1;
+namespace {
+const char versionC[] = "version";
+const int maxFoldersVersion = 1;
+
+int numberOfSyncJournals(const QString &path)
+{
+    return QDir(path).entryList({ QStringLiteral(".sync_*.db"), QStringLiteral("._sync_*.db") }, QDir::Hidden | QDir::Files).size();
+}
+
+}
 
 namespace OCC {
 Q_LOGGING_CATEGORY(lcFolderMan, "gui.folder.manager", QtInfoMsg)
@@ -1331,7 +1339,7 @@ static QString checkPathValidityRecursive(const QString &path)
     Utility::NtfsPermissionLookupRAII ntfs_perm;
 #endif
     const QFileInfo selFile(path);
-    if (!QDir(path).entryList({ QStringLiteral(".sync_*.db"), QStringLiteral("._sync_*.db") }, QDir::Hidden | QDir::Files).isEmpty()) {
+    if (numberOfSyncJournals(selFile.filePath()) != 0) {
         return FolderMan::tr("The folder %1 is used in a folder sync connection!").arg(QDir::toNativeSeparators(selFile.filePath()));
     }
 
@@ -1474,5 +1482,15 @@ void FolderMan::restartApplication()
     }
 }
 
+Result<void, QString> FolderMan::unsupportedConfiguration(const QString &path) const
+{
+    if (numberOfSyncJournals(path) > 1) {
+        return tr("Multiple accounts are sharing the folder %1.\n"
+                  "This configuration is know to lead to dataloss and is no longer supported.\n"
+                  "Please consider removing this folder from the account and adding it again.")
+            .arg(path);
+    }
+    return {};
+}
 
 } // namespace OCC

src/gui/folderman.h

@@ -239,6 +239,8 @@ class FolderMan : public QObject
     void setDirtyProxy();
     void setDirtyNetworkLimits();
 
+    /** If the folder configuration is no longer supported this will return an error string */
+    Result<void, QString> unsupportedConfiguration(const QString &path) const;
 signals:
     /**
       * signal to indicate a folder has changed its sync state.

src/gui/folderstatusmodel.cpp

@@ -207,8 +207,15 @@ QVariant FolderStatusModel::data(const QModelIndex &index, int role) const
         return (f->syncResult().hasUnresolvedConflicts())
             ? QStringList(tr("There are unresolved conflicts. Click for details."))
             : QStringList();
-    case FolderStatusDelegate::FolderErrorMsg:
-        return f->syncResult().errorStrings();
+    case FolderStatusDelegate::FolderErrorMsg: {
+        auto errors = f->syncResult().errorStrings();
+        const auto legacyError = FolderMan::instance()->unsupportedConfiguration(f->path());
+        if (!legacyError) {
+            // the error message might contain new lines, the delegate only expect multiple single line values
+            errors.append(legacyError.error().split(QLatin1Char('\n')));
+        }
+        return errors;
+    }
     case FolderStatusDelegate::FolderInfoMsg:
         return f->virtualFilesEnabled() && f->vfs().mode() != Vfs::Mode::WindowsCfApi
             ? QStringList(tr("Virtual file support is enabled."))