Register the serial proxy service on Android 10 and below

daemon/src/main/kotlin/org/matrix/vector/daemon/ipc/ManagerService.kt

@@ -158,22 +158,9 @@ object ManagerService : ILSPManagerService.Stub() {
   fun openManager(withData: Uri?) {
     val intent = getManagerIntent() ?: return
     val launchIntent = Intent(intent).apply { data = withData }
-    runCatching {
-          activityManager?.startActivityAsUserWithFeature(
-              SystemContext.appThread,
-              "android",
-              null,
-              launchIntent,
-              launchIntent.type,
-              null,
-              null,
-              0,
-              0,
-              null,
-              null,
-              0)
-        }
-        .onFailure { Log.e(TAG, "Failed to open manager", it) }
+    // Negative results are `ActivityManager.START_*` errors, the positive ones are all successes.
+    val result = activityManager?.startActivityAsUserCompat(launchIntent, 0) ?: -1
+    if (result < 0) Log.e(TAG, "Failed to open manager: $result")
   }
 
   /** Fixes permissions for the WebView cache. */
@@ -376,19 +363,7 @@ object ManagerService : ILSPManagerService.Stub() {
         wm?.lockNow(null)
       }
     }
-    return activityManager?.startActivityAsUserWithFeature(
-        SystemContext.appThread,
-        "android",
-        null,
-        intent,
-        intent.type,
-        null,
-        null,
-        0,
-        0,
-        null,
-        null,
-        userId) ?: -1
+    return activityManager?.startActivityAsUserCompat(intent, userId) ?: -1
   }
 
   override fun queryIntentActivitiesAsUser(

daemon/src/main/kotlin/org/matrix/vector/daemon/ipc/SystemServerService.kt

@@ -24,6 +24,8 @@ object SystemServerService : ILSPSystemServerService.Stub(), IBinder.DeathRecipi
     // Register as the service name early to setup an IPC for `system_server`.
     Log.d(TAG, "Registering bridge service for `system_server` with name `$serviceName`.")
 
+    // `IServiceManager.registerForNotifications` is only available since Android R.
+    // On older platforms we simply let the real service replace our proxy in servicemanager.
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
       val callback =
           object : IServiceCallback.Stub() {
@@ -39,13 +41,17 @@ object SystemServerService : ILSPSystemServerService.Stub(), IBinder.DeathRecipi
 
             override fun asBinder(): IBinder = this
           }
-      runCatching {
-            getSystemServiceManager().registerForNotifications(serviceName, callback)
-            ServiceManager.addService(serviceName, this)
-            proxyServiceName = serviceName
-          }
+      runCatching { getSystemServiceManager().registerForNotifications(serviceName, callback) }
           .onFailure { Log.e(TAG, "Failed to register IServiceCallback", it) }
     }
+
+    // The Zygisk module polls this name during `system_server` specialization,
+    // so it must be claimed on every supported platform.
+    runCatching {
+          ServiceManager.addService(serviceName, this)
+          proxyServiceName = serviceName
+        }
+        .onFailure { Log.e(TAG, "Failed to register proxy service `$serviceName`", it) }
   }
 
   override fun requestApplicationService(

daemon/src/main/kotlin/org/matrix/vector/daemon/system/SystemExtensions.kt

@@ -309,6 +309,34 @@ fun IActivityManager.broadcastIntentCompat(intent: Intent) {
       .onFailure { Log.e(TAG, "broadcastIntent failed", it) }
 }
 
+// `startActivityAsUserWithFeature` only arrived in Android R: on older platforms the same call
+// exists without the calling feature id, and using the newer one throws `NoSuchMethodError`.
+fun IActivityManager.startActivityAsUserCompat(intent: Intent, userId: Int): Int {
+  val appThread = SystemContext.appThread
+  return runCatching {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
+          startActivityAsUserWithFeature(
+              appThread,
+              "android",
+              null,
+              intent,
+              intent.type,
+              null,
+              null,
+              0,
+              0,
+              null,
+              null,
+              userId)
+        } else {
+          startActivityAsUser(
+              appThread, "android", intent, intent.type, null, null, 0, 0, null, null, userId)
+        }
+      }
+      .onFailure { Log.e(TAG, "startActivityAsUser failed", it) }
+      .getOrDefault(-1)
+}
+
 fun IUserManager.getUserName(userId: Int): String {
   return runCatching { getUserInfo(userId)?.name }.getOrNull() ?: userId.toString()
 }