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      1 /*
      2  * Copyright (C) 2016 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 ART_RUNTIME_PLUGIN_H_
     18 #define ART_RUNTIME_PLUGIN_H_
     19 
     20 #include <string>
     21 
     22 #include <android-base/logging.h>
     23 
     24 namespace art {
     25 
     26 // This function is loaded from the plugin (if present) and called during runtime initialization.
     27 // By the time this has been called the runtime has been fully initialized but not other native
     28 // libraries have been loaded yet. Failure to initialize is considered a fatal error.
     29 // TODO might want to give initialization function some arguments
     30 using PluginInitializationFunction = bool (*)();
     31 using PluginDeinitializationFunction = bool (*)();
     32 
     33 // A class encapsulating a plugin. There is no stable plugin ABI or API and likely never will be.
     34 // TODO Might want to put some locking in this but ATM we only load these at initialization in a
     35 // single-threaded fashion so not much need
     36 class Plugin {
     37  public:
     38   static Plugin Create(const std::string& lib) {
     39     return Plugin(lib);
     40   }
     41 
     42   bool IsLoaded() const {
     43     return dlopen_handle_ != nullptr;
     44   }
     45 
     46   const std::string& GetLibrary() const {
     47     return library_;
     48   }
     49 
     50   bool Load(/*out*/std::string* error_msg);
     51   bool Unload();
     52 
     53 
     54   ~Plugin() {
     55     if (IsLoaded() && !Unload()) {
     56       LOG(ERROR) << "Error unloading " << this;
     57     }
     58   }
     59 
     60   Plugin(const Plugin& other);
     61 
     62   // Create move constructor for putting this in a list
     63   Plugin(Plugin&& other) noexcept
     64       : library_(other.library_),
     65         dlopen_handle_(other.dlopen_handle_) {
     66     other.dlopen_handle_ = nullptr;
     67   }
     68 
     69  private:
     70   explicit Plugin(const std::string& library) : library_(library), dlopen_handle_(nullptr) { }
     71 
     72   std::string library_;
     73   void* dlopen_handle_;
     74 
     75   friend std::ostream& operator<<(std::ostream &os, Plugin const& m);
     76 };
     77 
     78 std::ostream& operator<<(std::ostream &os, Plugin const& m);
     79 std::ostream& operator<<(std::ostream &os, const Plugin* m);
     80 
     81 }  // namespace art
     82 
     83 #endif  // ART_RUNTIME_PLUGIN_H_
     84