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:
PluginLoader(const char * dir,const char * entry)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 
~PluginLoader()61     ~PluginLoader() {
62         for (size_t i = 0; i < factories.size(); i++) {
63             delete factories[i];
64         }
65     }
66 
getFactory(size_t i)67     T *getFactory(size_t i) const {
68         return factories[i];
69     }
70 
factoryCount()71     size_t factoryCount() const {return factories.size();}
72 
73   private:
loadOne(const char * path,const char * entry)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             } else {
89                 ALOGE("Failed to lookup symbol %s in library %s: %s",
90                         entry, path, library->lastError());
91             }
92         }
93         return NULL;
94     }
95 
96     Vector<T *> factories;
97     Vector<sp<SharedLibrary> > libraries;
98 
99     PluginLoader(const PluginLoader &) = delete;
100     void operator=(const PluginLoader &) = delete;
101 };
102 
103 }
104 }
105 }
106 }
107 } // namespace android
108 
109 #endif // PLUGIN_LOADER_H_
110 
111