1 /*
2 * Copyright (C) 2020 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 #define LOG_TAG "FactoryHalHidl"
18
19 #include <media/audiohal/FactoryHalHidl.h>
20
21 #include <dlfcn.h>
22
23 #include <android/hidl/manager/1.0/IServiceManager.h>
24 #include <hidl/ServiceManagement.h>
25 #include <hidl/Status.h>
26 #include <utils/Log.h>
27
28 namespace android::detail {
29
30 namespace {
31 /** Supported HAL versions, in order of preference.
32 */
33 const char* sAudioHALVersions[] = {
34 "6.0",
35 "5.0",
36 "4.0",
37 "2.0",
38 nullptr
39 };
40
createHalService(const std::string & version,const std::string & interface,void ** rawInterface)41 bool createHalService(const std::string& version, const std::string& interface,
42 void** rawInterface) {
43 const std::string libName = "libaudiohal@" + version + ".so";
44 const std::string factoryFunctionName = "create" + interface;
45 constexpr int dlMode = RTLD_LAZY;
46 void* handle = nullptr;
47 dlerror(); // clear
48 handle = dlopen(libName.c_str(), dlMode);
49 if (handle == nullptr) {
50 const char* error = dlerror();
51 ALOGE("Failed to dlopen %s: %s", libName.c_str(),
52 error != nullptr ? error : "unknown error");
53 return false;
54 }
55 void* (*factoryFunction)();
56 *(void **)(&factoryFunction) = dlsym(handle, factoryFunctionName.c_str());
57 if (!factoryFunction) {
58 const char* error = dlerror();
59 ALOGE("Factory function %s not found in library %s: %s",
60 factoryFunctionName.c_str(), libName.c_str(),
61 error != nullptr ? error : "unknown error");
62 dlclose(handle);
63 return false;
64 }
65 *rawInterface = (*factoryFunction)();
66 ALOGW_IF(!*rawInterface, "Factory function %s from %s returned nullptr",
67 factoryFunctionName.c_str(), libName.c_str());
68 return true;
69 }
70
hasHalService(const std::string & package,const std::string & version,const std::string & interface)71 bool hasHalService(const std::string& package, const std::string& version,
72 const std::string& interface) {
73 using ::android::hidl::manager::V1_0::IServiceManager;
74 sp<IServiceManager> sm = ::android::hardware::defaultServiceManager();
75 if (!sm) {
76 ALOGE("Failed to obtain HIDL ServiceManager");
77 return false;
78 }
79 // Since audio HAL doesn't support multiple clients, avoid instantiating
80 // the interface right away. Instead, query the transport type for it.
81 using ::android::hardware::Return;
82 using Transport = IServiceManager::Transport;
83 const std::string fqName = package + "@" + version + "::" + interface;
84 const std::string instance = "default";
85 Return<Transport> transport = sm->getTransport(fqName, instance);
86 if (!transport.isOk()) {
87 ALOGE("Failed to obtain transport type for %s/%s: %s",
88 fqName.c_str(), instance.c_str(), transport.description().c_str());
89 return false;
90 }
91 return transport != Transport::EMPTY;
92 }
93
94 } // namespace
95
createPreferredImpl(const std::string & package,const std::string & interface)96 void* createPreferredImpl(const std::string& package, const std::string& interface) {
97 for (auto version = detail::sAudioHALVersions; version != nullptr; ++version) {
98 void* rawInterface = nullptr;
99 if (hasHalService(package, *version, interface)
100 && createHalService(*version, interface, &rawInterface)) {
101 return rawInterface;
102 }
103 }
104 return nullptr;
105 }
106
107 } // namespace android::detail
108