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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 PLUGIN_LOADER_H_
     18 #define PLUGIN_LOADER_H_
     19 
     20 #include "SharedLibrary.h"
     21 #include <utils/Log.h>
     22 #include <utils/String8.h>
     23 #include <utils/Vector.h>
     24 
     25 namespace android {
     26 namespace hardware {
     27 namespace drm {
     28 namespace V1_0 {
     29 namespace helper {
     30 
     31 template <class T>
     32 class PluginLoader {
     33 
     34   public:
     35     PluginLoader(const char *dir, const char *entry) {
     36         /**
     37          * scan all plugins in the plugin directory and add them to the
     38          * factories list.
     39          */
     40         String8 pluginDir(dir);
     41 
     42         DIR* pDir = opendir(pluginDir.string());
     43         if (pDir == NULL) {
     44             ALOGE("Failed to find plugin directory %s", pluginDir.string());
     45         } else {
     46             struct dirent* pEntry;
     47             while ((pEntry = readdir(pDir))) {
     48                 String8 file(pEntry->d_name);
     49                 if (file.getPathExtension() == ".so") {
     50                     String8 path = pluginDir + "/" + pEntry->d_name;
     51                     T *plugin = loadOne(path, entry);
     52                     if (plugin) {
     53                         factories.push(plugin);
     54                     }
     55                 }
     56             }
     57             closedir(pDir);
     58         }
     59     }
     60 
     61     ~PluginLoader() {
     62         for (size_t i = 0; i < factories.size(); i++) {
     63             delete factories[i];
     64         }
     65     }
     66 
     67     T *getFactory(size_t i) const {
     68         return factories[i];
     69     }
     70 
     71     size_t factoryCount() const {return factories.size();}
     72 
     73   private:
     74     T* loadOne(const char *path, const char *entry) {
     75         sp<SharedLibrary> library = new SharedLibrary(String8(path));
     76         if (!library.get()) {
     77             ALOGE("Failed to open plugin library %s: %s", path,
     78                     library->lastError());
     79         } else {
     80             typedef T *(*CreateFactoryFunc)();
     81             CreateFactoryFunc createFactoryFunc =
     82                     (CreateFactoryFunc)library->lookup(entry);
     83             if (createFactoryFunc) {
     84                 ALOGV("Found plugin factory entry %s in %s", entry, path);
     85                 libraries.push(library);
     86                 T* result = createFactoryFunc();
     87                 return  result;
     88            }
     89         }
     90         return NULL;
     91     }
     92 
     93     Vector<T *> factories;
     94     Vector<sp<SharedLibrary> > libraries;
     95 
     96     PluginLoader(const PluginLoader &) = delete;
     97     void operator=(const PluginLoader &) = delete;
     98 };
     99 
    100 }
    101 }
    102 }
    103 }
    104 } // namespace android
    105 
    106 #endif // PLUGIN_LOADER_H_
    107 
    108