Fix network drive detection

changelog/unreleased/8272

@@ -0,0 +1,5 @@
+Bugfix: Correctly detect network drives
+
+We fixed a bug which allowed to use Virtual files on Windows network drives, which is not supported by Windows.
+
+https://github.com/owncloud/client/issues/8272

src/common/vfs.cpp

@@ -68,13 +68,18 @@ Result<bool, QString> Vfs::checkAvailability(const QString &path)
     const auto mode = bestAvailableVfsMode();
 #ifdef Q_OS_WIN
     if (mode == Mode::WindowsCfApi) {
-        if (QDir(QDir(path).canonicalPath()).isRoot()) {
+        const auto info = QFileInfo(path);
+        if (QDir(info.canonicalPath()).isRoot()) {
             return tr("The Virtual filesystem feature does not support a drive as sync root");
         }
-        const auto fs = FileSystem::fileSystemForPath(path);
+        const auto fs = FileSystem::fileSystemForPath(info.absoluteFilePath());
         if (fs != QLatin1String("NTFS")) {
             return tr("The Virtual filesystem feature requires a NTFS file system, %1 is using %2").arg(path, fs);
         }
+        const auto type = GetDriveTypeW(reinterpret_cast<const wchar_t *>(QDir::toNativeSeparators(info.absoluteFilePath().mid(0, 3)).utf16()));
+        if (type == DRIVE_REMOTE) {
+            return tr("The Virtual filesystem feature is not supported on network drives");
+        }
     }
 #else
     Q_UNUSED(path);