I need to pass some binary data between two android apps using Content Provider (sharedUserId is not an option).

I would prefer not to pass the data (a savegame stored as a file, small in size < 20k) as a file (ie. overriding openFile()) since this would necessitate some complicated temp-file scheme to cope with concurrency with several content provider accesses and a running game.

I would like to read the file into memory under a mutex lock and then pass the binary array in the simplest way possible. How do I do this?

It seems creating a file in memory is not a possibility due to the return type of openFile().

query() needs to return a Cursor. Using MatrixCursor is not possible since it applies toString() to all stored objects when reading it.

What do I need to do? Implement a custom Cursor? This class has 30 abstract methods. Do I read the file, put it in a SQLite db and return the cursor?

The complexity of this seemingly simple task is mindboggling.