IssueTracker

Build: AI-192.7142.36.36.6186006, 202002060328,

AI-192.7142.36.36.6186006, JRE 1.8.0_212-release-1586-b04x64 JetBrains s.r.o, OS Windows 10(amd64) v10.0 , screens 1920x1200, 1920x1200

AS: 3.6 RC 3; Kotlin plugin: 1.3.61; Android Gradle Plugin: 3.6.0-rc03; Gradle: 5.6.4; NDK: from local.properties: (not specified), latest from SDK: (not found); LLDB: pinned revision 3.1 not found, latest from SDK: (package not found); CMake: from local.properties: (not specified), latest from SDK: (not found), from PATH: (not found)

Any app which uses a ContentResolver to invoke takePersistableUriPermission() in the manner described by the Android docs will fail doing so after 128 grants. For example:

    private void chooseSamplePhotos() {
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType("*/*");
        intent.setFlags(Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION | Intent.FLAG_GRANT_READ_URI_PERMISSION);
        String[] mimeTypes = {"image/*","video/*"};
        intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);
        intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
        startActivityForResult(intent, FIND_FILES_CODE);
    }

Then in onActivityResult, assuming the user selected multiple files:
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    if ( resultCode != Activity.RESULT_OK ||
         requestCode != FIND_FILES_CODE ||
         data == null ) {
        return;
    }
    int takeFlags = data.getFlags() & (Intent.FLAG_GRANT_READ_URI_PERMISSION);
    ArrayList<Uri> uriList = new ArrayList<>();
    ContentResolver contentResolver = getContentResolver();
    Uri uri = null;
    try {
       uri = data.getData();
       if (uri != null) {
          // Single item selected
          contentResolver.takePersistableUriPermission(uri, takeFlags);
          uriList.add(uri);
       } else {
          ClipData clipData = data.getClipData();
          if (clipData != null) {
            // Multiple items chosen
            for (int x = 0; x < clipData.getItemCount(); x++) {
               uri = clipData.getItemAt(x).getUri();
               contentResolver.takePersistableUriPermission(uri, takeFlags);
               uriList.add(uri);
            }
          } else {
            return;
          }
       }
     } catch (SecurityException se) {
       Log.e("Test",
             "Got SecurityException attempting to take persisted URI permissions, message was: " +
             se.getMessage());
       return;
     }
}

This appears to be built in to the framework (see com.android.server.uri.UriGrantsManagerService, where private static final int MAX_PERSISTED_URI_GRANTS = 128 is defined and utilized).

This is artificially quite low. Our app, for example, allows users to create media playlists that reference media from a variety of sources via Uri, and we need persistence granted in order to accommodate their ability to reference these items upon application reboot. The work-around to use ACTION_GET_CONTENT and store media locally makes no sense in this case - why copy media to the mobile device when it is already stored in the cloud and can simply be streamed as needed?

It is understandable that a Uri may no longer be valid after some period of time and that this is a risk the app developer makes when utilizing ACTION_OPEN_DOCUMENT and takePersistableUriPermission(). However, it should be up to the app to manage that - not be prevented from handling an exception involving a Uri no longer being valid because the grant wasn't allowed in the first place.

If there is concern within the Android framework that allowing "unlimited" grants will bog down the system (which is a reasonable concern), there are better ways of handling this than artificially limiting it to 128.

I suggest allowing the limit to be set as a property (or if not, raising the value from 128 to much higher), then if that limit is reached throw something other than a security exception so the developer can implement a recycling strategy.

For the latter, it would be very helpful to have a simple "grant recycling policy/framework" available that would make it easy to identify grants that could be the subject of a FIFO or LIFO recycling policy.