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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef SYSTEM_CORE_INCLUDE_BINDERWRAPPER_BINDER_WRAPPER_H_
     18 #define SYSTEM_CORE_INCLUDE_BINDERWRAPPER_BINDER_WRAPPER_H_
     19 
     20 #include <sys/types.h>
     21 
     22 #include <string>
     23 
     24 #include <base/callback.h>
     25 #include <utils/StrongPointer.h>
     26 
     27 namespace android {
     28 
     29 class BBinder;
     30 class IBinder;
     31 
     32 // Wraps libbinder to make it testable.
     33 // NOTE: Static methods of this class are not thread-safe.
     34 class BinderWrapper {
     35  public:
     36   virtual ~BinderWrapper() {}
     37 
     38   // Creates and initializes the singleton (using a wrapper that communicates
     39   // with the real binder system).
     40   static void Create();
     41 
     42   // Initializes |wrapper| as the singleton, taking ownership of it. Tests that
     43   // want to inject their own wrappers should call this instead of Create().
     44   static void InitForTesting(BinderWrapper* wrapper);
     45 
     46   // Destroys the singleton. Must be called before calling Create() or
     47   // InitForTesting() a second time.
     48   static void Destroy();
     49 
     50   // Returns the singleton instance previously created by Create() or set by
     51   // InitForTesting().
     52   static BinderWrapper* Get();
     53 
     54   // Returns the singleton instance if it was previously created by Create() or
     55   // set by InitForTesting(), or creates a new one by calling Create().
     56   static BinderWrapper* GetOrCreateInstance();
     57 
     58   // Gets the binder for communicating with the service identified by
     59   // |service_name|, returning null immediately if it doesn't exist.
     60   virtual sp<IBinder> GetService(const std::string& service_name) = 0;
     61 
     62   // Registers |binder| as |service_name| with the service manager.
     63   virtual bool RegisterService(const std::string& service_name,
     64                                const sp<IBinder>& binder) = 0;
     65 
     66   // Creates a local binder object.
     67   virtual sp<BBinder> CreateLocalBinder() = 0;
     68 
     69   // Registers |callback| to be invoked when |binder| dies. If another callback
     70   // is currently registered for |binder|, it will be replaced.
     71   virtual bool RegisterForDeathNotifications(
     72       const sp<IBinder>& binder,
     73       const ::base::Closure& callback) = 0;
     74 
     75   // Unregisters the callback, if any, for |binder|.
     76   virtual bool UnregisterForDeathNotifications(const sp<IBinder>& binder) = 0;
     77 
     78   // When called while in a transaction, returns the caller's UID or PID.
     79   virtual uid_t GetCallingUid() = 0;
     80   virtual pid_t GetCallingPid() = 0;
     81 
     82  private:
     83   static BinderWrapper* instance_;
     84 };
     85 
     86 }  // namespace android
     87 
     88 #endif  // SYSTEM_CORE_INCLUDE_BINDERWRAPPER_BINDER_WRAPPER_H_
     89