Support partners to expose their own system libs to Android apps

Partners (entities other than AOSP) can expose their own system
libraries which are in /system/lib[64] to Android apps. This can be done
by adding the name of the libs into the files
/system/etc/public.libraries-<companyname>.txt.

There can be multiple of the txt files on a device, which is for the
case that multiple partners contributing to the same system image
have their own set of public libraries.

The public libraries MUST be named as lib<name>.<companyname>.so. This
is to prevent accidental exposure of AOSP-defined system private libs.

Note 1:
<companyname> doesn't need to be the same as the value of the sysprop
ro.product.manufacturer or anything that can be part of a file path.

Note 2:
This feature is not for exposing SoC-specific libs to Android apps. That
is already done by /vendor/etc/public.libraries.txt and is only for
libs in /vendor/lib[64].

Bug: 68280171
Test: mm -j under /system/core/libnativeloader/test
cts-tradefed run commandAndExit cts-dev -m CtsJniTestCases -t
android.jni.cts.JniStaticTest#test_linker_namespaces

Change-Id: I7d32ec27c7858e35b96c7c98223cc110acb35b81
6 files changed