Add JNI method to retrieve the binder

for services in the mainline module.

Bug: 365585450
Flag: com.android.wifi.flags.mainline_supplicant
Test: Manual test - verify that we can
      retrieve the binder and call a method
      in the mainline supplicant service
Change-Id: I1c25f839826042098f2186b03b0eb807edb76db8

4 files changed, 110 insertions, 0 deletions

diff --git a/apex/Android.bp b/apex/Android.bp
index a878695458..f570b8cebd 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -35,6 +35,9 @@ apex_defaults {
         "ServiceWifiResources",
         "WifiDialog",
     ],
+    jni_libs: [
+        "libservice-wifi-jni",
+    ],
     defaults: ["r-launched-apex-module"],
     // Indicates that pre-installed version of this apex can be compressed.
     // Whether it actually will be compressed is controlled on per-device basis.
diff --git a/jni/Android.bp b/jni/Android.bp
new file mode 100644
index 0000000000..d67c6aaf3f
--- /dev/null
+++ b/jni/Android.bp
@@ -0,0 +1,17 @@
+cc_library_shared {
+    name: "libservice-wifi-jni",
+    min_sdk_version: "30",
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    srcs: [
+        "com_android_server_ServiceManagerWrapper.cpp",
+    ],
+    shared_libs: [
+        "libbinder_ndk",
+    ],
+    apex_available: [
+        "com.android.wifi",
+    ],
+}
diff --git a/jni/com_android_server_ServiceManagerWrapper.cpp b/jni/com_android_server_ServiceManagerWrapper.cpp
new file mode 100644
index 0000000000..2a7a37dd80
--- /dev/null
+++ b/jni/com_android_server_ServiceManagerWrapper.cpp
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <android/binder_auto_utils.h>
+#include <android/binder_ibinder_jni.h>
+#include <android/binder_manager.h>
+#include <jni.h>
+
+namespace android {
+
+// nativeWaitForService
+extern "C" JNIEXPORT jobject JNICALL
+    Java_com_android_server_wifi_mainline_1supplicant_ServiceManagerWrapper_nativeWaitForService__Ljava_lang_String_2(
+        JNIEnv* env, jobject /* clazz */, jstring serviceNameJni) {
+    // AServiceManager_isDeclared and AServiceManager_waitForService were added in Android 31.
+    // Because this method will only be called on 35+, we can suppress the availability warning.
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wunguarded-availability"
+    const char* serviceName = env->GetStringUTFChars(serviceNameJni, nullptr);
+    if (AServiceManager_isDeclared(serviceName)) {
+        return AIBinder_toJavaBinder(env, AServiceManager_waitForService(serviceName));
+    } else {
+        return nullptr;
+    }
+    #pragma clang diagnostic pop
+}
+
+}; // namespace android
diff --git a/service/java/com/android/server/wifi/mainline_supplicant/ServiceManagerWrapper.java b/service/java/com/android/server/wifi/mainline_supplicant/ServiceManagerWrapper.java
new file mode 100644
index 0000000000..828d694431
--- /dev/null
+++ b/service/java/com/android/server/wifi/mainline_supplicant/ServiceManagerWrapper.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.wifi.mainline_supplicant;
+
+import android.annotation.Nullable;
+import android.os.IBinder;
+
+import com.android.modules.utils.build.SdkLevel;
+
+/**
+ * Wrapper around ServiceManager APIs that are not directly available to the mainline module.
+ */
+public final class ServiceManagerWrapper {
+    static {
+        System.loadLibrary("service-wifi-jni");
+    }
+
+    /**
+     * Returns the specified service from the service manager.
+     *
+     * If the service is not running, service manager will attempt to start it, and this function
+     * will wait for it to be ready.
+     *
+     * @return {@code null} only if there are permission problems or fatal errors
+     */
+    public static @Nullable IBinder waitForService(String serviceName) {
+        // Underlying implementation requires SDK 31+
+        if (!SdkLevel.isAtLeastS()) {
+            return null;
+        }
+        return nativeWaitForService(serviceName);
+    }
+
+    private static native IBinder nativeWaitForService(String serviceName);
+}