Android Content Provider Question

So, I’m having a look over different applications and there is one content provider I’m struggling a bit with:

Usually, content providers - at least the ones I know - have an authority defined like so:

<provider android:authorities="com.example.app1.contentprovider1"

Furthermore, one can query the content like so:
content query --uri "com.example.app1.contentprovider1/item"

However, this odd content provider I’m talking about, does not rely on overwriting Android’s query method, but rather overwrites openFile, which returns a ParcelFileDescriptor.

I have seen a similar app, where it was possible to read the etc/hosts file, because it requested the appropriate permissions. So, the reading of files is definitely possible.

However, I do not know how to read files on behalf of this application, nor where I could read up on that topic. Does someone have any suggestions?

Ok, it seems like I have partially solved it. I am able to access files I know the name of and I can also query them through adb lile so:

content read --uri content://com.example.app2/filename.dat

However, wildcards are not supported and I would need a way to iterate over all the files and show their content. When my app calls the openFile method a ParcelFileDescriptor, but I have yet to find a way to use this file descriptor to show the directory’s contents.