From e60564215dad37e03d05df069e4fe85575d63868 Mon Sep 17 00:00:00 2001
From: Joshua Gross <joshuagross@fb.com>
Date: Thu, 27 Aug 2020 19:56:53 -0700
Subject: [PATCH] ReactModalHostView: Prevent infinite SetState/UpdateState
 loop

Summary:
Make sure to check incoming state values before calling SetState, or we call back and forth forever.

Changelog: [internal]

Reviewed By: mdvacca

Differential Revision: D23389355

fbshipit-source-id: 9cf6110cf654fe93f555a6fbfd9b20f112214e0a
---
 .../uimanager/FabricViewStateManager.java     |  5 ++++
 .../react/views/modal/ReactModalHostView.java | 26 +++++++++++++++++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/FabricViewStateManager.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/FabricViewStateManager.java
index f78eedad134..073b91122f0 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/FabricViewStateManager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/FabricViewStateManager.java
@@ -9,6 +9,7 @@ package com.facebook.react.uimanager;
 
 import androidx.annotation.Nullable;
 import com.facebook.common.logging.FLog;
+import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.bridge.WritableMap;
 import com.facebook.react.config.ReactFeatureFlags;
 
@@ -91,4 +92,8 @@ public class FabricViewStateManager {
   public void setState(final StateUpdateCallback stateUpdateCallback) {
     setState(mStateWrapper, stateUpdateCallback, 0);
   }
+
+  public @Nullable ReadableMap getState() {
+    return mStateWrapper != null ? mStateWrapper.getState() : null;
+  }
 }
diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/modal/ReactModalHostView.java b/ReactAndroid/src/main/java/com/facebook/react/views/modal/ReactModalHostView.java
index 24d324fe709..d1bdd2f6faa 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/modal/ReactModalHostView.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/modal/ReactModalHostView.java
@@ -28,6 +28,7 @@ import com.facebook.react.R;
 import com.facebook.react.bridge.GuardedRunnable;
 import com.facebook.react.bridge.LifecycleEventListener;
 import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.bridge.UiThreadUtil;
 import com.facebook.react.bridge.WritableMap;
 import com.facebook.react.bridge.WritableNativeMap;
@@ -441,13 +442,34 @@ public class ReactModalHostView extends ViewGroup
 
     @UiThread
     public void updateState(final int width, final int height) {
+      final float realWidth = PixelUtil.toDIPFromPixel(width);
+      final float realHeight = PixelUtil.toDIPFromPixel(height);
+
+      // Check incoming state values. If they're already the correct value, return early to prevent
+      // infinite UpdateState/SetState loop.
+      ReadableMap currentState = getFabricViewStateManager().getState();
+      if (currentState != null) {
+        float delta = (float) 0.9;
+        float stateScreenHeight =
+            currentState.hasKey("screenHeight")
+                ? (float) currentState.getDouble("screenHeight")
+                : 0;
+        float stateScreenWidth =
+            currentState.hasKey("screenWidth") ? (float) currentState.getDouble("screenWidth") : 0;
+
+        if (Math.abs(stateScreenWidth - realWidth) < delta
+            && Math.abs(stateScreenHeight - realHeight) < delta) {
+          return;
+        }
+      }
+
       mFabricViewStateManager.setState(
           new FabricViewStateManager.StateUpdateCallback() {
             @Override
             public WritableMap getStateUpdate() {
               WritableMap map = new WritableNativeMap();
-              map.putDouble("screenWidth", PixelUtil.toDIPFromPixel(width));
-              map.putDouble("screenHeight", PixelUtil.toDIPFromPixel(height));
+              map.putDouble("screenWidth", realWidth);
+              map.putDouble("screenHeight", realHeight);
               return map;
             }
           });