1 /*
2  * Copyright 2022, 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 #include "CanBus.h"
18 
19 #include <android-base/logging.h>
20 #include <libnetdevice/libnetdevice.h>
21 
22 namespace aidl::android::hardware::automotive::can {
23 
CanBus(std::string_view ifname)24 CanBus::CanBus(std::string_view ifname) : mIfname(ifname) {}
25 
~CanBus()26 CanBus::~CanBus() {
27     std::lock_guard<std::mutex> lck(mIsUpGuard);
28     CHECK(!mIsUp) << "Interface is still up while being destroyed";
29 }
30 
preUp()31 Result CanBus::preUp() {
32     return Result::OK;
33 }
34 
postDown()35 bool CanBus::postDown() {
36     return true;
37 }
38 
getIfaceName()39 std::string CanBus::getIfaceName() {
40     return mIfname;
41 }
42 
up()43 Result CanBus::up() {
44     std::lock_guard<std::mutex> lck(mIsUpGuard);
45 
46     if (mIsUp) {
47         LOG(WARNING) << "Interface is already up";
48         return Result::INVALID_STATE;
49     }
50 
51     const auto preResult = preUp();
52     if (preResult != Result::OK) return preResult;
53 
54     const auto isUp = ::android::netdevice::isUp(mIfname);
55     if (!isUp.has_value()) {
56         // preUp() should prepare the interface (either create or make sure it's there)
57         LOG(ERROR) << "Interface " << mIfname << " didn't get prepared";
58         return Result::BAD_INTERFACE_ID;
59     }
60 
61     if (!*isUp && !::android::netdevice::up(mIfname)) {
62         LOG(ERROR) << "Can't bring " << mIfname << " up";
63         return Result::UNKNOWN_ERROR;
64     }
65     mDownAfterUse = !*isUp;
66 
67     mIsUp = true;
68     return Result::OK;
69 }
70 
down()71 Result CanBus::down() {
72     std::lock_guard<std::mutex> lck(mIsUpGuard);
73 
74     if (!mIsUp) {
75         LOG(WARNING) << "Interface is already down";
76         return Result::INVALID_STATE;
77     }
78     mIsUp = false;
79 
80     Result success = Result::OK;
81 
82     if (mDownAfterUse && !::android::netdevice::down(mIfname)) {
83         LOG(ERROR) << "Can't bring " << mIfname << " down";
84         // don't return yet, let's try to do best-effort cleanup
85         success = Result::UNKNOWN_ERROR;
86     }
87 
88     if (!postDown()) success = Result::UNKNOWN_ERROR;
89 
90     return success;
91 }
92 
93 }  // namespace aidl::android::hardware::automotive::can
94