Bug: 146511931

Clone this repo:
  1. a6caee8 Document SdkExtensions module structure by Anton Hansson · 3 weeks ago master
  2. 5c3325b Merge "Test static methods are accessible in updated apis" by Anton Hansson · 4 weeks ago android-r-beta-2 android-r-beta-3
  3. 93976bc Merge "Add script to update prebuilt dex" by Anton Hansson · 4 weeks ago
  4. a6da617 Test static methods are accessible in updated apis by Anton Hansson · 6 weeks ago
  5. 5d3a4ed Add script to update prebuilt dex by Anton Hansson · 6 weeks ago

SdkExtensions module

SdkExtensions is a module that decides the extension SDK level of the device, and provides APIs for applications to query the extension SDK level.

Structure

The module is packaged in an apex, com.android.sdkext, and has two components:

  • bin/derive_sdk: Native binary that runs early in the device boot process and reads metadata of other modules, to set system properties relating to the extension SDK (for instance build.version.extensions.r).
  • javalib/framework-sdkextension.jar: This is a jar on the bootclasspath that exposes APIs to applications to query the extension SDK level.

Deriving extension SDK level

derive_sdk is a program that reads metadata stored in other apex modules, in the form of binary protobuf files in subpath etc/sdkinfo.binarypb inside each apex. The structure of this protobuf can be seen here. The exact steps for converting a set of metadata files to actual extension versions is likely to change over time, and should not be depended upon.

Reading extension SDK level

The module exposes a java class SdkExtensions in the package android.os.ext. The method getExtensionVersion(int) can be used to read the version of a particular sdk extension, e.g. getExtensionVersion(Build.VERSION_CODES.R).