CODEWITHSUNDEEP
androidandroid-permissionsandroid-external-storageandroid-storage
Charles Li
Charles Li

Reputation: 1925

Why is READ_EXTERNAL_STORAGE permission request not needed to read file from external storage?

I'm testing my app on an emulator. I have an export function where I create and write to a file in the external storage's downloads directory. And I also have an import function where I read a file from the external storage's downloads directory.

From Android documentation:

If the device is running Android 5.1 or lower, or your app's target SDK is 22 or lower: If you list a dangerous permission in your manifest, the user has to grant the permission when they install the app; if they do not grant the permission, the system does not install the app at all.

If the device is running Android 6.0 or higher, and your app's target SDK is 23 or higher: The app has to list the permissions in the manifest, and it must request each dangerous permission it needs while the app is running. The user can grant or deny each permission, and the app can continue to run with limited capabilities even if the user denies a permission request.

My emulator is running on Android 6.0 and my app's target SDK is 25, therefore I must also request each dangerous permission it needs while the app is running. I did so for the export functionality and everything works properly. However, when I'm implementing the import function I didn't request a permission during runtime. And the strange thing is I'm still able to read from my external storage's permission without READ_EXTERNAL_STORAGE being requested and granted at runtime. READ_EXTERNAL_STORAGE is a dangerous permission according to this Android documentation .

To verify, I made sure to disable permissions before I started using the feature and after it is completed, I verified again that the permission still wasn't granted. Although I'm happy with the behaviour since it's working without me requesting permission at runtime, but according to the documentations I don't believe this behaviour is expected. That's why I will like to know what's causing this and to figure out the problem before I publish any changes for the app.

Here's a code snippet of my manifest:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

The code snippet where I pick a file to read:

Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
            intent.setType("text/*");
            startActivityForResult(intent, GET_FILE_RESULT_CODE);

The code snippet where I read the file chosen from the code snippet above (exportFile is simply the URI from onActivityResult):

    BufferedReader br;
    try {
        br = new BufferedReader(new InputStreamReader(context.getContentResolver().openInputStream(exportFile)));
        String line;
        // Skip first header line
        br.readLine();
        while ((line = br.readLine()) != null) {...}

Thanks!

Upvotes: 4

Views: 3844

Answers (2)

Prokash Sarkar
Prokash Sarkar

Reputation: 11873

There's a well explanation here,

READ_EXTERNAL_STORAGE

Provides protected read access to external storage. In Android 4.1 by default all applications still have read access. This will be changed in a future release to require that applications explicitly request read access using this permission. If your application already requests write access, it will automatically get read access as well. There is a new developer option to turn on read access restriction, for developers to test their applications against how Android will behave in the future.

In short, READ_EXTERNAL_STORAGE only exists as of Jelly Bean (Level 16). So, unless you're using a Jelly Bean phone and set the developer option "Protect USB storage" it won't be a problem.

Upvotes: 3

alanjet
alanjet

Reputation: 9

You know,Android Runtime Permissions are grouped, since you applied for WRITE_EXTERNAL_STORAGE permission in the manifest already, so there's no need to apply for READ_EXTERNAL_STORAGE permissions.Both of them are the same group.

Upvotes: 0

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