Display Toast with linker warnings after Activity.onStart()

Displays list of problems linker encountered with app's
native code including
1. Unauthorized access to private platform libraries.
2. Text relocations
3. Invalid DT_NEEDED entires

This change is intended only for preview/beta releases and to
be reverted before the first release build.

Bug: http://b/27365747
Change-Id: I08735472059248c901ef22042682d574fb2b0c92

core/java/android/app/Activity.java

@@ -41,6 +41,7 @@ import android.content.Intent;
 import android.content.IntentSender;
 import android.content.SharedPreferences;
 import android.content.pm.ActivityInfo;
+import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.res.Configuration;
@@ -68,6 +69,7 @@ import android.os.Parcelable;
 import android.os.PersistableBundle;
 import android.os.RemoteException;
 import android.os.StrictMode;
+import android.os.SystemProperties;
 import android.os.UserHandle;
 import android.text.Selection;
 import android.text.SpannableStringBuilder;
@@ -110,6 +112,7 @@ import android.view.WindowManager;
 import android.view.WindowManagerGlobal;
 import android.view.accessibility.AccessibilityEvent;
 import android.widget.AdapterView;
+import android.widget.Toast;
 import android.widget.Toolbar;
 
 import com.android.internal.app.IVoiceInteractor;
@@ -832,6 +835,8 @@ public class Activity extends ContextThemeWrapper
     private boolean mHasCurrentPermissionsRequest;
     private boolean mEatKeyUpEvent;
 
+    private static native String getDlWarning();
+
     /** Return the intent that started this activity. */
     public Intent getIntent() {
         return mIntent;
@@ -6621,6 +6626,31 @@ public class Activity extends ContextThemeWrapper
         }
         mFragments.dispatchStart();
         mFragments.reportLoaderStart();
+
+        // This property is set for all builds except final release
+        boolean isDlwarningEnabled = SystemProperties.getInt("ro.bionic.ld.warning", 0) == 1;
+        boolean isAppDebuggable =
+                (mApplication.getApplicationInfo().flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0;
+
+        if (isAppDebuggable || isDlwarningEnabled) {
+            String dlwarning = getDlWarning();
+            if (dlwarning != null) {
+                String appName = getString(mApplication.getApplicationInfo().labelRes);
+                String warning = "Detected problems with app native libraries\n" +
+                                 "(please consult log for detail):\n" + dlwarning;
+                if (isAppDebuggable) {
+                      new AlertDialog.Builder(this).
+                          setTitle(appName).
+                          setMessage(warning).
+                          setPositiveButton(android.R.string.ok, null).
+                          setCancelable(false).
+                          show();
+                } else {
+                    Toast.makeText(this, appName + "\n" + warning, Toast.LENGTH_LONG).show();
+                }
+            }
+        }
+
         mActivityTransitionState.enterReady(this);
     }