Android 7.0 introduced namespaces for native libraries to limit internal API visibility and resolve situations when apps accidentally end up using platform libraries instead of their own. See the Improving Stability with Private C/C++ Symbol Restrictions in Android 7.0 Android Developers blog post for application-specific changes.
The change separates system libraries from application libraries and makes it hard to use internal system libraries by accident (and vice versa).
Namespaces for native libraries prevent apps from using private-platform native
APIs (as was done with OpenSSL). It also removes situations where apps
accidentally end up using platform libraries instead of their own (as witnessed
Adding additional native libraries
In addition to standard public native libraries, silicon vendors (starting from Android 7.0) and device manufactures (starting from Android 9) may choose to provide additional native libraries accessible to apps by putting them under the respective library folders and explicitly listing them in .txt files.
The library folders are:
/vendor/lib(for 32-bit) and
/vendor/lib64(for 64-bit) for libraries from silicon vendors
/system/lib(for 32-bit) and
/system/lib64(for 64-bit) for libraries from device manufacturers
/vendor/etc/public.libraries.txtfor libraries from silicon vendors
/system/etc/public.libraries-COMPANYNAME.txtfor libraries from device manufacturers, where
COMPANYNAMErefers to a name of the manufacturer (such as
COMPANYNAMEshould match with
[A-Za-z0-9_.-]+; alphanumeric characters, _, . (dot) and -. It is possible to have multiple such .txt files in a device if some libraries are from external solution providers.
The .txt files are:
Native libraries in the
system partition that are made public by device manufacturers
MUST be named
In other words,
libFoo.so without the company name suffix MUST NOT be made public.
COMPANYNAME in the library file name MUST match with the
COMPANYNAME in the
txt file name in which the library name is listed.
Native libraries that are part of AOSP MUST NOT be made public (except the standard public native libraries which are public by default). Only the additional libraries added by silicon vendors or device manufacturers can be made accessible to apps.
Starting from Android 8.0, vendor public libraries have the following additional restrictions and required setups:
- The native library in vendor must be properly labeled so it can be
accessible to apps. If access is required by any apps (including third
party apps), the library must be labeled as
same_process_hal_filein a vendor-specific
file_contextsfile as follows:
libnative.sois the name of the native library.
- The library, either directly or transitively via its dependencies, must not
depend on system libraries other than VNDK-SP and LLNDK libraries. The list of
VNDK-SP and LLNDK libraries can be found at
Updating apps to not use non-public native libraries
This feature is enabled only for applications targeting SDK version 24 or later; for backward compatibility, see Table 1. What to expect if your app is linking against private native libraries. The list of Android native libraries accessible to apps (also know as public native libraries) is listed in CDD section 3.1.1. Apps targeting 24 or later and using any non-public libraries should be updated. Please see NDK Apps Linking to Platform Libraries for more details.