ServiceManagement.cpp revision 91e3f645694514794b39a054a39a2a0087583182 
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#define LOG_TAG "ServiceManagement"
18
19#include <hidl/HidlBinderSupport.h>
20#include <hidl/ServiceManagement.h>
21#include <hidl/Static.h>
22#include <hidl/Status.h>
23
24#include <android-base/logging.h>
25#include <array>
26#include <cstdio>
27#include <dlfcn.h>
28#include <hidl-util/FQName.h>
29#include <hidl-util/StringHelper.h>
30#include <hwbinder/IPCThreadState.h>
31#include <hwbinder/Parcel.h>
32#include <iostream>
33#include <unistd.h>
34#include <vector>
35
36#include <android/hidl/manager/1.0/IServiceManager.h>
37#include <android/hidl/manager/1.0/BpHwServiceManager.h>
38#include <android/hidl/manager/1.0/BnHwServiceManager.h>
39
40using android::hidl::manager::V1_0::IServiceManager;
41using android::hidl::manager::V1_0::IServiceNotification;
42using android::hidl::manager::V1_0::BpHwServiceManager;
43using android::hidl::manager::V1_0::BnHwServiceManager;
44
45namespace android {
46namespace hardware {
47
48sp<IServiceManager> defaultServiceManager() {
49
50    if (gDefaultServiceManager != NULL) return gDefaultServiceManager;
51    if (access("/dev/hwbinder", F_OK|R_OK|W_OK) != 0) {
52        // HwBinder not available on this device or not accessible to
53        // this process.
54        return nullptr;
55    }
56    {
57        AutoMutex _l(gDefaultServiceManagerLock);
58        while (gDefaultServiceManager == NULL) {
59            gDefaultServiceManager = fromBinder<IServiceManager, BpHwServiceManager, BnHwServiceManager>(
60                ProcessState::self()->getContextObject(NULL));
61            if (gDefaultServiceManager == NULL)
62                sleep(1);
63        }
64    }
65
66    return gDefaultServiceManager;
67}
68
69std::vector<std::string> command(const std::string &command) {
70    std::array<char, 128> buffer;
71    std::vector<std::string> results;
72
73    std::unique_ptr<FILE, std::function<decltype(pclose)>>
74        pipe(popen(command.c_str(), "r"), pclose);
75    std::string result;
76
77    while (!feof(pipe.get())) {
78        if (fgets(buffer.data(), buffer.size(), pipe.get()) == nullptr) {
79            break;
80        }
81
82        std::string partialResult(buffer.data());
83
84        if (!partialResult.size()) {
85            LOG(ERROR) << "Command failed: " << command;
86            return {}; // this should never happen
87        }
88
89        result += partialResult;
90
91        if (result.at(result.size() - 1) != '\n') {
92            continue; // keep on reading line
93        }
94
95        result = StringHelper::RTrim(result, "\n");
96
97        results.push_back(result);
98        result.clear();
99    }
100
101    if (ferror(pipe.get())) {
102        LOG(ERROR) << "Command failed: " << command;
103        return {};
104    }
105
106    return results;
107}
108
109struct PassthroughServiceManager : IServiceManager {
110    Return<sp<IBase>> get(const hidl_string& fqName,
111                     const hidl_string& name) override {
112        FQName iface(fqName);
113
114        if (!iface.isValid() ||
115            !iface.isFullyQualified() ||
116            iface.isIdentifier()) {
117            LOG(ERROR) << "Invalid interface name passthrough lookup: " << fqName;
118            return nullptr;
119        }
120
121        const int dlMode = RTLD_LAZY;
122        void *handle = nullptr;
123
124        std::string library;
125
126        // TODO: lookup in VINTF instead
127        // TODO: warn if multiple are found
128        // TODO(b/34135607): Remove HAL_LIBRARY_PATH_SYSTEM
129        for (const std::string &path : {
130            HAL_LIBRARY_PATH_ODM, HAL_LIBRARY_PATH_VENDOR, HAL_LIBRARY_PATH_SYSTEM
131        }) {
132            std::string find = "find " + path + iface.getPackageAndVersion().string()
133                             + "-impl*.so 2>/dev/null";
134
135            for (const std::string &lib : command(find)) {
136                handle = dlopen(lib.c_str(), dlMode);
137                if (handle != nullptr) {
138                    library = lib;
139                    goto beginLookup;
140                }
141            }
142        }
143
144        if (handle == nullptr) {
145            return nullptr;
146        }
147beginLookup:
148
149        const std::string sym = "HIDL_FETCH_" + iface.name();
150
151        IBase* (*generator)(const char* name);
152        *(void **)(&generator) = dlsym(handle, sym.c_str());
153        if(!generator) {
154            LOG(ERROR) << "Passthrough lookup opened " << library
155                       << " but could not find symbol " << sym;
156            return nullptr;
157        }
158        return (*generator)(name);
159    }
160
161    Return<bool> add(const hidl_vec<hidl_string>& /* interfaceChain */,
162                     const hidl_string& /* name */,
163                     const sp<IBase>& /* service */) override {
164        LOG(FATAL) << "Cannot register services with passthrough service manager.";
165        return false;
166    }
167
168    Return<void> list(list_cb /* _hidl_cb */) override {
169        // TODO: add this functionality
170        LOG(FATAL) << "Cannot list services with passthrough service manager.";
171        return Void();
172    }
173    Return<void> listByInterface(const hidl_string& /* fqInstanceName */,
174                                 listByInterface_cb /* _hidl_cb */) override {
175        // TODO: add this functionality
176        LOG(FATAL) << "Cannot list services with passthrough service manager.";
177        return Void();
178    }
179
180    Return<bool> registerForNotifications(const hidl_string& /* fqName */,
181                                          const hidl_string& /* name */,
182                                          const sp<IServiceNotification>& /* callback */) override {
183        // This makes no sense.
184        LOG(FATAL) << "Cannot register for notifications with passthrough service manager.";
185        return false;
186    }
187
188};
189
190sp<IServiceManager> getPassthroughServiceManager() {
191    static sp<PassthroughServiceManager> manager(new PassthroughServiceManager());
192    return manager;
193}
194
195}; // namespace hardware
196}; // namespace android
197