questions about leveldb::RepairDB

[minggrim]

Hi,
I have two questions about process crash or system crash during leveldb::RepairDB

1. In the flow Repairer::Run -> Repairer::WriteDescriptor.
   In my understanding, 000001.dbtmp is created as a temporary file to store VersionSet information, then RenameFile to MANIFEST-000001. If the process crash before RenameFile called. the 000001.dbtmp left.
   Is it possible that we fail to recover db in next time because of 000001.dbtmp exist ?

Status WriteDescriptor() {                                                                                                                                                                                        
    std::string tmp = TempFileName(dbname_, 1);
    WritableFile* file;
    Status status = env_->NewWritableFile(tmp, &file);
    if (!status.ok()) {
      return status;
    }
    ...
}

If yes, is it safe that I delete the [0-9]+.dbtmp before Open db?

2. When log.AddRecord(record) to 000001.dbtmp, EmitPhysicalRecord call Flush() to system buffer.
   Is it content safe if system crash after RenameFile(000001.dbtmp, MANIFEST-000001).

Please forgive me if I misunderstand the code flow about recovery process.