5 files changed, 81 insertions, 6 deletions

diff --git a/libs/binder/ndk/ibinder.cpp b/libs/binder/ndk/ibinder.cpp
index 7540cae391..d287290a8d 100644
--- a/libs/binder/ndk/ibinder.cpp
+++ b/libs/binder/ndk/ibinder.cpp
@@ -698,3 +698,14 @@ void AIBinder_setRequestingSid(AIBinder* binder, bool requestingSid) {
 const char* AIBinder_getCallingSid() {
     return ::android::IPCThreadState::self()->getCallingSid();
 }
+
+android::sp<android::IBinder> AIBinder_toPlatformBinder(AIBinder* binder) {
+    if (binder == nullptr) return nullptr;
+    return binder->getBinder();
+}
+
+AIBinder* AIBinder_fromPlatformBinder(const android::sp<android::IBinder>& binder) {
+    sp<AIBinder> ndkBinder = ABpBinder::lookupOrCreateFromBinder(binder);
+    AIBinder_incStrong(ndkBinder.get());
+    return ndkBinder.get();
+}
diff --git a/libs/binder/ndk/include_platform/android/binder_ibinder_platform.h b/libs/binder/ndk/include_platform/android/binder_ibinder_platform.h
index 1f5a2373a2..d4feabac8a 100644
--- a/libs/binder/ndk/include_platform/android/binder_ibinder_platform.h
+++ b/libs/binder/ndk/include_platform/android/binder_ibinder_platform.h
@@ -18,6 +18,10 @@
 
 #include <android/binder_ibinder.h>
 
+#if !defined(__ANDROID_APEX__) && !defined(__ANDROID_VNDK__)
+#include <binder/IBinder.h>
+#endif
+
 __BEGIN_DECLS
 
 /**
@@ -44,3 +48,33 @@ void AIBinder_setRequestingSid(AIBinder* binder, bool requestingSid) __INTRODUCE
 __attribute__((warn_unused_result)) const char* AIBinder_getCallingSid() __INTRODUCED_IN(31);
 
 __END_DECLS
+
+#if !defined(__ANDROID_APEX__) && !defined(__ANDROID_VNDK__)
+
+/**
+ * Get libbinder version of binder from AIBinder.
+ *
+ * WARNING: function calls to a local object on the other side of this function
+ * will parcel. When converting between binders, keep in mind it is not as
+ * efficient as a direct function call.
+ *
+ * \param binder binder with ownership retained by the client
+ * \return platform binder object
+ */
+android::sp<android::IBinder> AIBinder_toPlatformBinder(AIBinder* binder);
+
+/**
+ * Get libbinder_ndk version of binder from platform binder.
+ *
+ * WARNING: function calls to a local object on the other side of this function
+ * will parcel. When converting between binders, keep in mind it is not as
+ * efficient as a direct function call.
+ *
+ * \param binder platform binder which may be from anywhere (doesn't have to be
+ * created with libbinder_ndK)
+ * \return binder with one reference count of ownership given to the client. See
+ * AIBinder_decStrong
+ */
+AIBinder* AIBinder_fromPlatformBinder(const android::sp<android::IBinder>& binder);
+
+#endif
diff --git a/libs/binder/ndk/libbinder_ndk.map.txt b/libs/binder/ndk/libbinder_ndk.map.txt
index d58b75c2d2..9b5fa26303 100644
--- a/libs/binder/ndk/libbinder_ndk.map.txt
+++ b/libs/binder/ndk/libbinder_ndk.map.txt
@@ -95,8 +95,6 @@ LIBBINDER_NDK { # introduced=29
     AServiceManager_addService; # apex llndk
     AServiceManager_checkService; # apex llndk
     AServiceManager_getService; # apex llndk
-  local:
-    *;
 };
 
 LIBBINDER_NDK30 { # introduced=30
@@ -111,19 +109,21 @@ LIBBINDER_NDK30 { # introduced=30
     AIBinder_markVendorStability; # llndk
     AIBinder_markVintfStability; # apex llndk
     AIBinder_Class_setHandleShellCommand; # apex llndk
-  local:
-    *;
 };
 
 LIBBINDER_NDK31 { # introduced=31
   global:
     AIBinder_getCallingSid; # apex
     AIBinder_setRequestingSid; # apex
-  local:
-    *;
 };
 
 LIBBINDER_NDK_PLATFORM {
   global:
     AParcel_getAllowFds;
+    extern "C++" {
+        AIBinder_fromPlatformBinder*;
+        AIBinder_toPlatformBinder*;
+    };
+  local:
+    *;
 };
diff --git a/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl b/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl
index 4bba9e4317..dc77467d8c 100644
--- a/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl
+++ b/libs/binder/ndk/tests/IBinderNdkUnitTest.aidl
@@ -22,6 +22,8 @@
 import IEmpty;
 
 interface IBinderNdkUnitTest {
+    int repeatInt(int a);
+
     void takeInterface(IEmpty test);
     void forceFlushCommands();
 
diff --git a/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp b/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp
index 6869220727..e3fdb4bab3 100644
--- a/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp
+++ b/libs/binder/ndk/tests/libbinder_ndk_unit_test.cpp
@@ -44,6 +44,10 @@ constexpr char kExistingNonNdkService[] = "SurfaceFlinger";
 constexpr char kBinderNdkUnitTestService[] = "BinderNdkUnitTest";
 
 class MyBinderNdkUnitTest : public aidl::BnBinderNdkUnitTest {
+    ndk::ScopedAStatus repeatInt(int32_t in, int32_t* out) {
+        *out = in;
+        return ndk::ScopedAStatus::ok();
+    }
     ndk::ScopedAStatus takeInterface(const std::shared_ptr<aidl::IEmpty>& empty) {
         (void)empty;
         return ndk::ScopedAStatus::ok();
@@ -329,6 +333,30 @@ TEST(NdkBinder, SentAidlBinderCanBeDestroyed) {
     EXPECT_TRUE(destroyed);
 }
 
+TEST(NdkBinder, ConvertToPlatformBinder) {
+    for (const ndk::SpAIBinder& binder :
+         {// remote
+          ndk::SpAIBinder(AServiceManager_getService(kBinderNdkUnitTestService)),
+          // local
+          ndk::SharedRefBase::make<MyBinderNdkUnitTest>()->asBinder()}) {
+        // convert to platform binder
+        EXPECT_NE(binder.get(), nullptr);
+        sp<IBinder> platformBinder = AIBinder_toPlatformBinder(binder.get());
+        EXPECT_NE(platformBinder.get(), nullptr);
+        auto proxy = interface_cast<IBinderNdkUnitTest>(platformBinder);
+        EXPECT_NE(proxy, nullptr);
+
+        // use platform binder
+        int out;
+        EXPECT_TRUE(proxy->repeatInt(4, &out).isOk());
+        EXPECT_EQ(out, 4);
+
+        // convert back
+        ndk::SpAIBinder backBinder = ndk::SpAIBinder(AIBinder_fromPlatformBinder(platformBinder));
+        EXPECT_EQ(backBinder.get(), binder.get());
+    }
+}
+
 class MyResultReceiver : public BnResultReceiver {
    public:
     Mutex mMutex;