CODEWITHSUNDEEP
android
Movsar Bekaev
Movsar Bekaev

Reputation: 908

SharedUserId & Files

Can sharedUserId provide access to files in the data/data/com.example/files dir?

I tried to do that, and I can retrieve the context and check if this dir is exists, although when I trying to read files from it the debuger gives me PERMISSION DENIED error.

They say in documentation that SharedUserId provides shared access to data and even can run two apps in the same process, what is the data about what they are saying? Can it be that this feature gives only access to 'static' resources of the application and not to the ones that have been created dynamically?

UPD

fw_context = createPackageContext("com.example", Context.CONTEXT_IGNORE_SECURITY);
String[] str = fw_context.getFilesDir.list();//str=null

As I have commented, the str here is null, I don't know why it's null, but I know that there is some files in this dir (I have rooted phone so I can see this)

Upvotes: 2

Views: 694

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006614

Can sharedUserId provide access to files in the data/data/com.example/files dir?

Yes, if and only if:

  • Both apps have the same non-empty sharedUserId value

  • Both apps have always had the same non-empty sharedUserID value (i.e., you cannot update an app from not having sharedUserId to having a sharedUserId)

  • Both apps are signed by the same signing key

That being said, sharedUserId is almost never the right answer, for the simple reason that neither app will know about what the other app is doing with the files. Use a ContentProvider (or some other form of IPC) to share content between apps, using signature-level permissions or other identity checks to ensure that only the right apps can interact over the IPC channel.

Upvotes: 4

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