From 4b8a0e1ddb980a2bc609a49201d84200dc415c03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Oliv=C3=A9r=20Falvai?= <oliver.falvai@bitrise.io>
Date: Mon, 24 Aug 2026 15:03:03 +0200
Subject: [PATCH] Android: opt-in flag for bsdiff patches

---
 .../com/microsoft/codepush/react/CodePush.java     | 14 +++++++++++++-
 .../codepush/react/CodePushUpdateManager.java      | 12 ++++++++----
 docs/api-android.md                                |  5 +++++
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/android/app/src/main/java/com/microsoft/codepush/react/CodePush.java b/android/app/src/main/java/com/microsoft/codepush/react/CodePush.java
index ceafd545..0563b08a 100644
--- a/android/app/src/main/java/com/microsoft/codepush/react/CodePush.java
+++ b/android/app/src/main/java/com/microsoft/codepush/react/CodePush.java
@@ -70,7 +70,8 @@ public static String getServiceUrl() {
     private CodePush(String deploymentKey, Context context, boolean isDebugMode) {
         mContext = context.getApplicationContext();
 
-        mUpdateManager = new CodePushUpdateManager(context.getFilesDir().getAbsolutePath());
+        boolean enableBinaryDiffUpdates = getBooleanCustomPropertyFromStringsIfExist("EnableBinaryDiffUpdates", false);
+        mUpdateManager = new CodePushUpdateManager(context.getFilesDir().getAbsolutePath(), enableBinaryDiffUpdates);
         mTelemetryManager = new CodePushTelemetryManager(mContext);
         mDeploymentKey = deploymentKey;
         mIsDebugMode = isDebugMode;
@@ -156,6 +157,17 @@ private String getCustomPropertyFromStringsIfExist(String propertyName) {
         return null;
     }
 
+    private boolean getBooleanCustomPropertyFromStringsIfExist(String propertyName, boolean defaultValue) {
+        String packageName = mContext.getPackageName();
+        int resId = mContext.getResources().getIdentifier("CodePush" + propertyName, "bool", packageName);
+
+        if (resId != 0) {
+            return mContext.getResources().getBoolean(resId);
+        }
+
+        return defaultValue;
+    }
+
     public void clearDebugCacheIfNeeded(boolean isLiveReloadEnabled) {
         // for checking if we use LiveReload mode. In this case we should not remove ReactNativeDevBundle.js file
         // because we get error with trying to get this after reloading. Issue: https://github.com/microsoft/react-native-code-push/issues/1272
diff --git a/android/app/src/main/java/com/microsoft/codepush/react/CodePushUpdateManager.java b/android/app/src/main/java/com/microsoft/codepush/react/CodePushUpdateManager.java
index 7a16a360..34029c92 100644
--- a/android/app/src/main/java/com/microsoft/codepush/react/CodePushUpdateManager.java
+++ b/android/app/src/main/java/com/microsoft/codepush/react/CodePushUpdateManager.java
@@ -24,9 +24,11 @@
 public class CodePushUpdateManager {
 
     private String mDocumentsDirectory;
+    private boolean mEnableBinaryDiffUpdates;
 
-    public CodePushUpdateManager(String documentsDirectory) {
+    public CodePushUpdateManager(String documentsDirectory, boolean enableBinaryDiffUpdates) {
         mDocumentsDirectory = documentsDirectory;
+        mEnableBinaryDiffUpdates = enableBinaryDiffUpdates;
     }
 
     private String getDownloadFilePath() {
@@ -260,12 +262,14 @@ public void downloadPackage(JSONObject updatePackage, String expectedBundleFileN
             if (isDiffUpdate) {
                 // Run patching after copyNecessaryFilesFromCurrentPackage() so patched output overwrites
                 // bytes copied in from the old package at the same paths.
-                if (diffManifest.getVersion() == 2) {
+                if (diffManifest.getVersion() > 2 || diffManifest.getVersion() < 1) {
+                    throw new IOException("Diff manifest version " + diffManifest.getVersion() + " is not supported by this SDK version.");
+                } else if (diffManifest.getVersion() == 2 && !mEnableBinaryDiffUpdates) {
+                    throw new IOException("Received a binary diff update, but binary diff updates are not enabled on this client. Set CodePushEnableBinaryDiffUpdates to true in strings.xml to enable them.");
+                } else if (diffManifest.getVersion() == 2) {
                     String currentPackageFolderPath = getCurrentPackageFolderPath();
                     BinaryDiffPatcher.applyBinaryDiffPatches(diffManifest, new File(currentPackageFolderPath), new File(unzippedFolderPath), new File(newUpdateFolderPath));
                     FileUtils.deleteDirectoryAtPath(new File(newUpdateFolderPath, CodePushConstants.DIFF_PATCHES_FOLDER_NAME).getPath());
-                } else if (diffManifest.getVersion() > 2) {
-                    throw new IOException("Diff manifest version " + diffManifest.getVersion() + " is not supported by this SDK version.");
                 }
             }
 
diff --git a/docs/api-android.md b/docs/api-android.md
index 092bfbb4..34120923 100644
--- a/docs/api-android.md
+++ b/docs/api-android.md
@@ -15,6 +15,11 @@ Since `autolinking` uses `react-native.config.js` to link plugins, constructors
   <string moduleConfig="true" name="CodePushServerUrl">https://yourcodepush.server.com</string>
   ```
 
+- **Enable Binary Diff Updates** - switch for applying binary diff (bsdiff) patches during a diff update, off by default (at the moment). When disabled, only file-by-file diffing is applied (for example, skipping assets if only the main JS bundle changed, but that whole file is downloaded byte for byte). Add a `bool` resource named `CodePushEnableBinaryDiffUpdates` to `strings.xml` to turn it on:
+  ```xml
+  <bool moduleConfig="true" name="CodePushEnableBinaryDiffUpdates">true</bool>
+  ```
+
 The Java API is made available by importing the `com.microsoft.codepush.react.CodePush` class into your `MainActivity.java` file, and consists of a single public class named `CodePush`.
 
 ### Java API Reference (Android)