4 files changed, 131 insertions, 0 deletions
diff --git a/libs/binder/ndk/include_platform/android/binder_manager.h b/libs/binder/ndk/include_platform/android/binder_manager.h
index 055c79bca1..52bcd20d9e 100644
--- a/libs/binder/ndk/include_platform/android/binder_manager.h
+++ b/libs/binder/ndk/include_platform/android/binder_manager.h
@@ -18,6 +18,7 @@
 
 #include <android/binder_ibinder.h>
 #include <android/binder_status.h>
+#include <sys/cdefs.h>
 
 __BEGIN_DECLS
 
@@ -50,4 +51,47 @@ __attribute__((warn_unused_result)) AIBinder* AServiceManager_checkService(const
  */
 __attribute__((warn_unused_result)) AIBinder* AServiceManager_getService(const char* instance);
 
+/**
+ * Registers a lazy service with the default service manager under the 'instance' name.
+ * Does not take ownership of binder.
+ * The service must be configured statically with init so it can be restarted with
+ * ctl.interface.* messages from servicemanager.
+ * AServiceManager_registerLazyService cannot safely be used with AServiceManager_addService
+ * in the same process. If one service is registered with AServiceManager_registerLazyService,
+ * the entire process will have its lifetime controlled by servicemanager.
+ * Instead, all services in the process should be registered using
+ * AServiceManager_registerLazyService.
+ *
+ * \param binder object to register globally with the service manager.
+ * \param instance identifier of the service. This will be used to lookup the service.
+ *
+ * \return STATUS_OK on success.
+ */
+binder_status_t AServiceManager_registerLazyService(AIBinder* binder, const char* instance)
+        __INTRODUCED_IN(31);
+
+/**
+ * Gets a binder object with this specific instance name. Efficiently waits for the service.
+ * If the service is not declared, it will wait indefinitely. Requires the threadpool
+ * to be started in the service.
+ * This also implicitly calls AIBinder_incStrong (so the caller of this function is responsible
+ * for calling AIBinder_decStrong).
+ *
+ * \param instance identifier of the service used to lookup the service.
+ *
+ * \return service if registered, null if not.
+ */
+__attribute__((warn_unused_result)) AIBinder* AServiceManager_waitForService(const char* instance)
+        __INTRODUCED_IN(31);
+
+/**
+ * Check if a service is declared (e.g. VINTF manifest).
+ *
+ * \param instance identifier of the service.
+ *
+ * \return true on success, meaning AServiceManager_waitForService should always
+ *    be able to return the service.
+ */
+bool AServiceManager_isDeclared(const char* instance) __INTRODUCED_IN(31);
+
 __END_DECLS
diff --git a/libs/binder/ndk/libbinder_ndk.map.txt b/libs/binder/ndk/libbinder_ndk.map.txt
index d4353823a0..1701fb5705 100644
--- a/libs/binder/ndk/libbinder_ndk.map.txt
+++ b/libs/binder/ndk/libbinder_ndk.map.txt
@@ -117,6 +117,9 @@ LIBBINDER_NDK31 { # introduced=31
     ABinderProcess_setupPolling; # apex
     AIBinder_getCallingSid; # apex
     AIBinder_setRequestingSid; # apex
+    AServiceManager_isDeclared; # apex llndk
+    AServiceManager_registerLazyService; # llndk
+    AServiceManager_waitForService; # apex llndk
 };
 
 LIBBINDER_NDK_PLATFORM {
diff --git a/libs/binder/ndk/service_manager.cpp b/libs/binder/ndk/service_manager.cpp
index d0b166d318..6b2184ebaa 100644
--- a/libs/binder/ndk/service_manager.cpp
+++ b/libs/binder/ndk/service_manager.cpp
@@ -20,6 +20,7 @@
 #include "status_internal.h"
 
 #include <binder/IServiceManager.h>
+#include <binder/LazyServiceRegistrar.h>
 
 using ::android::defaultServiceManager;
 using ::android::IBinder;
@@ -61,3 +62,33 @@ AIBinder* AServiceManager_getService(const char* instance) {
     AIBinder_incStrong(ret.get());
     return ret.get();
 }
+binder_status_t AServiceManager_registerLazyService(AIBinder* binder, const char* instance) {
+    if (binder == nullptr || instance == nullptr) {
+        return STATUS_UNEXPECTED_NULL;
+    }
+
+    auto serviceRegistrar = android::binder::LazyServiceRegistrar::getInstance();
+    status_t status = serviceRegistrar.registerService(binder->getBinder(), instance);
+
+    return PruneStatusT(status);
+}
+AIBinder* AServiceManager_waitForService(const char* instance) {
+    if (instance == nullptr) {
+        return nullptr;
+    }
+
+    sp<IServiceManager> sm = defaultServiceManager();
+    sp<IBinder> binder = sm->waitForService(String16(instance));
+
+    sp<AIBinder> ret = ABpBinder::lookupOrCreateFromBinder(binder);
+    AIBinder_incStrong(ret.get());
+    return ret.get();
+}
+bool AServiceManager_isDeclared(const char* instance) {
+    if (instance == nullptr) {
+        return false;
+    }
+
+    sp<IServiceManager> sm = defaultServiceManager();
+    return sm->isDeclared(String16(instance));
+}
diff --git a/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp b/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp
index 9b2fcf009a..332b4ca5b8 100644
--- a/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp
+++ b/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp
@@ -43,6 +43,7 @@ using namespace android;
 
 constexpr char kExistingNonNdkService[] = "SurfaceFlinger";
 constexpr char kBinderNdkUnitTestService[] = "BinderNdkUnitTest";
+constexpr char kLazyBinderNdkUnitTestService[] = "LazyBinderNdkUnitTest";
 
 class MyBinderNdkUnitTest : public aidl::BnBinderNdkUnitTest {
     ndk::ScopedAStatus repeatInt(int32_t in, int32_t* out) {
@@ -143,6 +144,27 @@ int manualThreadPoolService(const char* instance) {
     return 1;
 }
 
+int lazyService(const char* instance) {
+    ABinderProcess_setThreadPoolMaxThreadCount(0);
+    // Wait to register this service to make sure the main test process will
+    // actually wait for the service to be available. Tested with sleep(60),
+    // and reduced for sake of time.
+    sleep(1);
+    // Strong reference to MyBinderNdkUnitTest kept by service manager.
+    // This is just for testing, it has no corresponding init behavior.
+    auto service = ndk::SharedRefBase::make<MyBinderNdkUnitTest>();
+    auto binder = service->asBinder();
+
+    binder_status_t status = AServiceManager_registerLazyService(binder.get(), instance);
+    if (status != STATUS_OK) {
+        LOG(FATAL) << "Could not register: " << status << " " << instance;
+    }
+
+    ABinderProcess_joinThreadPool();
+
+    return 1;  // should not return
+}
+
 // This is too slow
 // TEST(NdkBinder, GetServiceThatDoesntExist) {
 //     sp<IFoo> foo = IFoo::getService("asdfghkl;");
@@ -171,6 +193,33 @@ TEST(NdkBinder, DoubleNumber) {
     EXPECT_EQ(2, out);
 }
 
+TEST(NdkBinder, GetLazyService) {
+    // Not declared in the vintf manifest
+    ASSERT_FALSE(AServiceManager_isDeclared(kLazyBinderNdkUnitTestService));
+    ndk::SpAIBinder binder(AServiceManager_waitForService(kLazyBinderNdkUnitTestService));
+    std::shared_ptr<aidl::IBinderNdkUnitTest> service =
+            aidl::IBinderNdkUnitTest::fromBinder(binder);
+    ASSERT_NE(service, nullptr);
+
+    EXPECT_EQ(STATUS_OK, AIBinder_ping(binder.get()));
+}
+
+// This is too slow
+TEST(NdkBinder, CheckLazyServiceShutDown) {
+    ndk::SpAIBinder binder(AServiceManager_waitForService(kLazyBinderNdkUnitTestService));
+    std::shared_ptr<aidl::IBinderNdkUnitTest> service =
+            aidl::IBinderNdkUnitTest::fromBinder(binder);
+    ASSERT_NE(service, nullptr);
+
+    EXPECT_EQ(STATUS_OK, AIBinder_ping(binder.get()));
+    binder = nullptr;
+    service = nullptr;
+    IPCThreadState::self()->flushCommands();
+    // Make sure the service is dead after some time of no use
+    sleep(10);
+    ASSERT_EQ(nullptr, AServiceManager_checkService(kLazyBinderNdkUnitTestService));
+}
+
 void LambdaOnDeath(void* cookie) {
     auto onDeath = static_cast<std::function<void(void)>*>(cookie);
     (*onDeath)();
@@ -477,6 +526,10 @@ int main(int argc, char* argv[]) {
     }
     if (fork() == 0) {
         prctl(PR_SET_PDEATHSIG, SIGHUP);
+        return lazyService(kLazyBinderNdkUnitTestService);
+    }
+    if (fork() == 0) {
+        prctl(PR_SET_PDEATHSIG, SIGHUP);
         return generatedService();
     }