FolderWatcher: Become unreliable if test notification fails #7241

Necessary for some filesystems on windows that don't have full file
watching capabilities.

src/gui/folder.cpp

@@ -1194,6 +1194,7 @@ void Folder::registerFolderWatcher()
     connect(_folderWatcher.data(), &FolderWatcher::becameUnreliable,
         this, &Folder::slotWatcherUnreliable);
     _folderWatcher->init(path());
+    _folderWatcher->startNotificatonTest(path() + QLatin1String(".owncloudsync.log"));
 }
 
 bool Folder::supportsVirtualFiles() const

src/gui/folderwatcher.cpp

@@ -33,6 +33,7 @@
 #endif
 
 #include "folder.h"
+#include "filesystem.h"
 
 namespace OCC {
 
@@ -75,6 +76,26 @@ bool FolderWatcher::isReliable() const
     return _isReliable;
 }
 
+void FolderWatcher::startNotificatonTest(const QString &path)
+{
+    ASSERT(_testNotificationPath.isEmpty());
+    _testNotificationPath = path;
+
+    if (QFile::exists(path)) {
+        auto mtime = FileSystem::getModTime(path);
+        FileSystem::setModTime(path, mtime + 1);
+    } else {
+        QFile f(path);
+        f.open(QIODevice::WriteOnly | QIODevice::Append);
+    }
+
+    QTimer::singleShot(5000, this, [&]() {
+        if (!_testNotificationPath.isEmpty())
+            emit becameUnreliable(tr("The watcher did not receive a test notification."));
+        _testNotificationPath.clear();
+    });
+}
+
 int FolderWatcher::testLinuxWatchCount() const
 {
 #ifdef Q_OS_LINUX
@@ -111,6 +132,10 @@ void FolderWatcher::changeDetected(const QStringList &paths)
     // ------- handle ignores:
     for (int i = 0; i < paths.size(); ++i) {
         QString path = paths[i];
+        if (!_testNotificationPath.isEmpty()
+            && Utility::fileNamesEqual(path, _testNotificationPath)) {
+            _testNotificationPath.clear();
+        }
         if (pathIsIgnored(path)) {
             continue;
         }

src/gui/folderwatcher.h

@@ -71,6 +71,14 @@ public:
      */
     bool isReliable() const;
 
+    /**
+     * Triggers a change in the path and verifies a notification arrives.
+     *
+     * If no notification is seen, the folderwatcher marks itself as unreliable.
+     * The path must be ignored by the watcher.
+     */
+    void startNotificatonTest(const QString &path);
+
     /// For testing linux behavior only
     int testLinuxWatchCount() const;
 
@@ -110,6 +118,9 @@ private:
     Folder *_folder;
     bool _isReliable = true;
 
+    /** Path of the expected test notification */
+    QString _testNotificationPath;
+
     friend class FolderWatcherPrivate;
 };
 }

src/gui/folderwatcher_linux.cpp

@@ -171,9 +171,10 @@ void FolderWatcherPrivate::slotReceivedNotification(int fd)
         if (event->len == 0 || event->wd <= -1)
             continue;
         QByteArray fileName(event->name);
+        // Filter out journal changes - redundant with filtering in
+        // FolderWatcher::pathIsIgnored.
         if (fileName.startsWith("._sync_")
             || fileName.startsWith(".csync_journal.db")
-            || fileName.startsWith(".owncloudsync.log")
             || fileName.startsWith(".sync_")) {
             continue;
         }