I want to write output from the TextToSpeech engine to my app's cache directory. In order to for the TTS to write there I first have to give it permissions to do so. But I don't know how. I understand that normally such problems can be solved by handing a FileDescriptor over thus giving permissions to access a specific file. But I can't do that with TTS, as the TextToSpeech.synthesizeToFile method only accepts the file path as a String, no FileDescriptor. So what to do?