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android / platform / packages / modules / SdkExtensions / refs/heads/android-s-v2-preview-1
commitad8bfd513ca9231a97a811453364affa769bfc12[log] [tgz]
authorsatayev <[email protected]>Wed Oct 20 13:39:38 2021 +0000
committersatayev <[email protected]>Thu Oct 21 17:12:34 2021 +0000
treee52f08bf29344295dc17ae2ccc047bafe417232f
parent8f77b3b02ab9553cf581def3b229357ee59f4853 [diff]
Enable preupload hook script to check java paths.

Bug: 203542767
Test: presubmit
Change-Id: I9f7052123a503ff5dd067557b023125f1d93e1b1
1 file changed
tree: e52f08bf29344295dc17ae2ccc047bafe417232f
  1. derive_classpath/
  2. derive_sdk/
  3. gen_sdk/
  4. java/
  5. javatests/
  6. Android.bp
  7. com.android.sdkext.avbpubkey
  8. com.android.sdkext.pem
  9. com.android.sdkext.pk8
  10. com.android.sdkext.x509.pem
  11. manifest.json
  12. OWNERS
  13. PREUPLOAD.cfg
  14. README.md
  15. TEST_MAPPING
README.md

SdkExtensions module

SdkExtensions module is responsible for:

  • deciding the extension SDK level of the device;
  • providing APIs for applications to query the extension SDK level;
  • determining the values for the BOOTCLASSPATH, DEX2OATBOOTCLASSPATH, and SYSTEMSERVERCLASSPATH environment variables.

General information

Structure

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

  • bin/derive_classpath: a native binary that runs early in the device boot process. It reads individual classpath configs files from the system and other modules, merges them, and defines the definition of *CLASSPATH environ variables.
  • 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.pb 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).

Deriving classpaths

derive_classpath service reads and merges individual config files in the /system/etc/classpaths/ and /apex/*/etc/classpaths. Each config stores protobuf message from classpaths.proto in a proto binary format. Exact merging algorithm that determines the order of the classpath entries is described in derive_classpath.cpp and may change over time.

Developer information

Adding a new extension version

For every new Android SDK level a new extension version should be defined. These are the steps necessary to do that:

  • Add the new modules in this extension version to the SdkModule enum in sdk.proto.
  • Update derive_sdk.cpp by:
  • mapping the modules' package names to the new enum values
  • creating a new set with the new enum values
  • set a new sysprop to the value of GetSdkLevel with the new enum set
  • add a unit test to derive_sdk_test.cpp verifying the new extensions works
  • Make the SdkExtensions.getExtensionVersion API support the new extensions.
  • Extend the CTS test to verify the above two behaviors.