From ba2b335b99b9fd43aeceb037d7ed61d94053baa2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rulong=20Chen=EF=BC=88=E9=99=88=E6=B1=9D=E9=BE=99=EF=BC=89?=
 <26625149+0xZOne@users.noreply.github.com>
Date: Wed, 3 Jan 2024 00:54:39 +0800
Subject: [PATCH] Fix NPE when platform plugin delegate is null
 (flutter/engine#49391)

Fixes:
https://github.com/flutter/flutter/issues/140600
https://github.com/flutter/flutter/issues/140031

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I added new tests to check the change I am making or feature I am
adding, or the PR is [test-exempt]. See [testing the engine] for
instructions on writing and running engine tests.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I signed the [CLA].
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#overview
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[test-exempt]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[C++, Objective-C, Java style guides]:
https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
[testing the engine]:
https://github.com/flutter/flutter/wiki/Testing-the-engine
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes
[Discord]: https://github.com/flutter/flutter/wiki/Chat
---
 .../flutter/plugin/platform/PlatformPlugin.java   |  8 +++++---
 .../plugin/platform/PlatformPluginTest.java       | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java b/engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java
index 6dbfedd9bb..9100476b74 100644
--- a/engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java
+++ b/engine/src/flutter/shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java
@@ -38,7 +38,7 @@ public class PlatformPlugin {
 
   private final Activity activity;
   private final PlatformChannel platformChannel;
-  private final PlatformPluginDelegate platformPluginDelegate;
+  @Nullable private final PlatformPluginDelegate platformPluginDelegate;
   private PlatformChannel.SystemChromeStyle currentTheme;
   private int mEnabledOverlays;
   private static final String TAG = "PlatformPlugin";
@@ -161,7 +161,7 @@ public class PlatformPlugin {
   public PlatformPlugin(
       @NonNull Activity activity,
       @NonNull PlatformChannel platformChannel,
-      @NonNull PlatformPluginDelegate delegate) {
+      @Nullable PlatformPluginDelegate delegate) {
     this.activity = activity;
     this.platformChannel = platformChannel;
     this.platformChannel.setPlatformMessageHandler(mPlatformMessageHandler);
@@ -499,7 +499,9 @@ public class PlatformPlugin {
   }
 
   private void setFrameworkHandlesBack(boolean frameworkHandlesBack) {
-    platformPluginDelegate.setFrameworkHandlesBack(frameworkHandlesBack);
+    if (platformPluginDelegate != null) {
+      platformPluginDelegate.setFrameworkHandlesBack(frameworkHandlesBack);
+    }
   }
 
   private void popSystemNavigator() {
diff --git a/engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformPluginTest.java b/engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformPluginTest.java
index 3d5fdbce74..1d312057d4 100644
--- a/engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformPluginTest.java
+++ b/engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformPluginTest.java
@@ -11,6 +11,7 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 import static org.mockito.Mockito.any;
 import static org.mockito.Mockito.anyBoolean;
 import static org.mockito.Mockito.doThrow;
@@ -613,6 +614,20 @@ public class PlatformPluginTest {
     verify(mockPlatformPluginDelegate, times(1)).setFrameworkHandlesBack(true);
   }
 
+  @Test
+  public void testPlatformPluginDelegateNull() throws Exception {
+    Activity mockActivity = mock(Activity.class);
+    PlatformPlugin platformPlugin =
+        new PlatformPlugin(mockActivity, mockPlatformChannel, null /*platformPluginDelegate*/);
+
+    try {
+      platformPlugin.mPlatformMessageHandler.setFrameworkHandlesBack(true);
+    } catch (NullPointerException e) {
+      // Not expected
+      fail("NullPointerException was thrown");
+    }
+  }
+
   @Test
   public void popSystemNavigatorFlutterActivity() {
     Activity mockActivity = mock(Activity.class);