Android :: INTENT_SEND And Attached Files

My app wants to send a data file by email. However, the data only exists inside the database. There is no physical file containing it. In order to make it possible to send this using INTENT_SEND, I need to return a file descriptor in ContentProvider.openFile(). This means I need to write my data out to a temporary file on disk somewhere so I can open it to get a real file descriptor. However, the email app doesn't necessarily use the file immediately, and *doesn't tell me* when it's finished with it, so I don't know when to remove the temporary file. As the file is likely to be quite large I don't want to keep it around for long periods.

What I'd really like to do is to be able to avoid the whole issue by using a callback to synthesise the data as and when the email app needs it, using some sort of pipe. Unfortunately due to the real file descriptor requirement I can't use Java pipes, there are no Unix fifo APIs that I can find, and you can't create a ParcelFileDescriptor from a Unix socket, which was my other option. Is there any easy way to do what I want, or do I need to start messing around with TCP sockets?