en/devices/tech/config/namespaces_libraries.html

page.title=Namespaces for Native Libraries
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    <h2>In this document</h2>
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<p>
Android 7.0 introduces 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 <a
href="http://android-developers.blogspot.com/2016/06/improving-stability-with-private-cc.html">Improving
Stability with Private C/C++ Symbol Restrictions in Android 7.0</a> Android
Developers blog post</a> for application-specific changes.
</p>

<h2 id="architecture">Architecture</h2>

<p>
The change separates system libraries from application libraries and makes it
hard to use internal system libraries by accident (and vice versa).
</p>

<img src="images/namespace-libraries.png" alt="Namespaces for native libraries" width="466" id="namespace-libraries" />
<p class="img-caption">
  <strong>Figure 1.</strong> Namespaces for native libraries
</p>

<p>
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
with <code>libpng</code>).
</p>

<h2 id="adding-additional-native-libraries">Adding additional native
libraries</h2>

<p>
In addition to standard public native libraries, vendors may choose to provide
additional native libraries accessible to apps by putting them under the
<code>/vendor</code> library folder (/vendor/lib for 32 bit libraries and,
/vendor/lib64 for 64 bit) and listing them in:
<code>/vendor/etc/public.libraries.txt</code>
</p>

<h2 id="updating-app-non-public">Updating apps to not use non-public native libraries</h2>

<p>
This feature is enabled only for applications targeting SDK version 24 or later;
for backward compatibility, see <a
href="http://android-developers.blogspot.com/2016/06/improving-stability-with-private-cc.html">Table
1. What to expect if your app is linking against private native libraries</a>.
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 <a
href="https://developer.android.com/preview/behavior-changes.html#ndk">NDK Apps
Linking to Platform Libraries </a> for more details.
</p>