Merge "Add libbinder_ndk systemapi support for injecting RPC binder accessors" into main

Author: Treehugger Robot

libs/binder/IServiceManager.cpp

@@ -157,12 +157,21 @@ class CppBackendShim : public IServiceManager {
 
 class AccessorProvider {
 public:
-    AccessorProvider(RpcAccessorProvider&& provider) : mProvider(std::move(provider)) {}
-    sp<IBinder> provide(const String16& name) { return mProvider(name); }
+    AccessorProvider(std::set<std::string>&& instances, RpcAccessorProvider&& provider)
+          : mInstances(std::move(instances)), mProvider(std::move(provider)) {}
+    sp<IBinder> provide(const String16& name) {
+        if (mInstances.count(String8(name).c_str()) > 0) {
+            return mProvider(name);
+        } else {
+            return nullptr;
+        }
+    }
+    const std::set<std::string>& instances() { return mInstances; }
 
 private:
     AccessorProvider() = delete;
 
+    std::set<std::string> mInstances;
     RpcAccessorProvider mProvider;
 };
 
@@ -318,10 +327,32 @@ sp<IServiceManager> getServiceManagerShimFromAidlServiceManagerForTests(
     return sp<CppBackendShim>::make(sp<BackendUnifiedServiceManager>::make(sm));
 }
 
-std::weak_ptr<AccessorProvider> addAccessorProvider(RpcAccessorProvider&& providerCallback) {
+// gAccessorProvidersMutex must be locked already
+static bool isInstanceProvidedLocked(const std::string& instance) {
+    return gAccessorProviders.end() !=
+            std::find_if(gAccessorProviders.begin(), gAccessorProviders.end(),
+                         [&instance](const AccessorProviderEntry& entry) {
+                             return entry.mProvider->instances().count(instance) > 0;
+                         });
+}
+
+std::weak_ptr<AccessorProvider> addAccessorProvider(std::set<std::string>&& instances,
+                                                    RpcAccessorProvider&& providerCallback) {
+    if (instances.empty()) {
+        ALOGE("Set of instances is empty! Need a non empty set of instances to provide for.");
+        return std::weak_ptr<AccessorProvider>();
+    }
     std::lock_guard<std::mutex> lock(gAccessorProvidersMutex);
+    for (const auto& instance : instances) {
+        if (isInstanceProvidedLocked(instance)) {
+            ALOGE("The instance %s is already provided for by a previously added "
+                  "RpcAccessorProvider.",
+                  instance.c_str());
+            return std::weak_ptr<AccessorProvider>();
+        }
+    }
     std::shared_ptr<AccessorProvider> provider =
-            std::make_shared<AccessorProvider>(std::move(providerCallback));
+            std::make_shared<AccessorProvider>(std::move(instances), std::move(providerCallback));
     std::weak_ptr<AccessorProvider> receipt = provider;
     gAccessorProviders.push_back(AccessorProviderEntry(std::move(provider)));
 
@@ -331,8 +362,9 @@ std::weak_ptr<AccessorProvider> addAccessorProvider(RpcAccessorProvider&& provid
 status_t removeAccessorProvider(std::weak_ptr<AccessorProvider> wProvider) {
     std::shared_ptr<AccessorProvider> provider = wProvider.lock();
     if (provider == nullptr) {
-        ALOGE("The provider supplied to removeAccessorProvider has already been removed.");
-        return NAME_NOT_FOUND;
+        ALOGE("The provider supplied to removeAccessorProvider has already been removed or the "
+              "argument to this function was nullptr.");
+        return BAD_VALUE;
     }
     std::lock_guard<std::mutex> lock(gAccessorProvidersMutex);
     size_t sizeBefore = gAccessorProviders.size();

libs/binder/include/binder/IServiceManager.h

@@ -24,6 +24,7 @@
 #include <utils/String16.h>
 #include <utils/Vector.h>
 #include <optional>
+#include <set>
 
 namespace android {
 
@@ -224,20 +225,36 @@ LIBBINDER_EXPORTED bool checkPermission(const String16& permission, pid_t pid, u
 typedef std::function<status_t(const String16& name, sockaddr* outAddr, socklen_t addrSize)>
         RpcSocketAddressProvider;
 
-typedef std::function<sp<IBinder>(const String16& name)> RpcAccessorProvider;
+/**
+ * This callback provides a way for clients to get access to remote services by
+ * providing an Accessor object from libbinder that can connect to the remote
+ * service over sockets.
+ *
+ * \param instance name of the service that the callback will provide an
+ *        Accessor for. The provided accessor will be used to set up a client
+ *        RPC connection in libbinder in order to return a binder for the
+ *        associated remote service.
+ *
+ * \return IBinder of the Accessor object that libbinder implements.
+ *         nullptr if the provider callback doesn't know how to reach the
+ *         service or doesn't want to provide access for any other reason.
+ */
+typedef std::function<sp<IBinder>(const String16& instance)> RpcAccessorProvider;
 
 class AccessorProvider;
 
 /**
- * Register an accessor provider for the service manager APIs.
+ * Register a RpcAccessorProvider for the service manager APIs.
  *
+ * \param instances that the RpcAccessorProvider knows about and can provide an
+ *        Accessor for.
  * \param provider callback that generates Accessors.
  *
  * \return A pointer used as a recept for the successful addition of the
  *         AccessorProvider. This is needed to unregister it later.
  */
 [[nodiscard]] LIBBINDER_EXPORTED std::weak_ptr<AccessorProvider> addAccessorProvider(
-        RpcAccessorProvider&& providerCallback);
+        std::set<std::string>&& instances, RpcAccessorProvider&& providerCallback);
 
 /**
  * Remove an accessor provider using the pointer provided by addAccessorProvider

libs/binder/ndk/Android.bp

@@ -95,6 +95,7 @@ cc_library {
         "persistable_bundle.cpp",
         "process.cpp",
         "service_manager.cpp",
+        "binder_rpc.cpp",
     ],
 
     static_libs: [