int TControlFunctions::InitRootFile() {
#if (DEBUG_MSG)
   cout << "+ TControlfunctions::InitRootFile()" << endl;
#endif
   // Create database file
   // return  0: file opened successful
   // return -1: file could not be opened
   // return -2: file info tree incurrupt or wrong version

   stringstream dbname;
   sema_gD->Wait();
   dbname << gD.gDatabaseName << ".root";

   TDatime dt;
   rootFile = new TFile(dbname.str().c_str(),"UPDATE","PaCTS TM Archive",FILE_COMPRESSION);
   if(rootFile->IsZombie()) {
      cout << "+ ERROR: opening file" << endl;
      return -1;
   }

   thisFileInfo.version = gD.gFileVersion;
   thisFileInfo.year    = dt.GetYear();
   thisFileInfo.month   = dt.GetMonth();
   thisFileInfo.hour    = dt.GetHour();
   thisFileInfo.minute  = dt.GetMinute();
   thisFileInfo.second  = dt.GetSecond();
   strcpy(thisFileInfo.dbname, gD.gDatabaseName.c_str());

   string treeName("file_info");
   string branchName("creation_info");

   // already exists a file information tree?
   treeFileInfo = (TTree*) rootFile->Get(treeName.c_str());
   if(treeFileInfo == NULL) {
      treeFileInfo = new TTree(treeName.c_str(),"General file information");
      treeFileInfo->Branch(branchName.c_str(), &thisFileInfo,
                        "fileVersion/F:year:month:hour:minute:second:database/C");
      treeFileInfo->Fill();
      treeFileInfo->Write();
   }
   else {
      // The tree exists! Check the file information:
      if(!treeFileInfo->GetBranchStatus(branchName.c_str())) {
         cout << "+ ERROR: file info branch not found" << endl;
         rootFile->Close();
         return -2;
      } else {
         TBranch* branch = NULL;
         branch = treeFileInfo->GetBranch(branchName.c_str());
         treeFileInfo->SetBranchAddress(branchName.c_str(), &thisFileInfo);
         treeFileInfo->GetEntry(0);

         // Check file version
         if(thisFileInfo.version != gD.gFileVersion) {
            cout << "+ ERROR: wrong file version | "
                 << "file: " << thisFileInfo.version << " "
                 << "should be: " << gD.gFileVersion
                 << endl;
            rootFile->Close();
            return -2;
         }

         // Check databasename
         if(strcmp(thisFileInfo.dbname, gD.gDatabaseName.c_str()) > 0 ||
            strcmp(thisFileInfo.dbname, gD.gDatabaseName.c_str()) < 0) {
            cout << "+ ERROR: wrong sql database | "
                 << "file: " << thisFileInfo.dbname << " "
                 << "should be: " << gD.gDatabaseName
                 << endl;
            rootFile->Close();
            return -2;
         }
      }
   }
   sema_gD->Post();
   delete treeFileInfo; 
   treeFileInfo = NULL;
   return 0;
}