AIDL CAN HAL

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Bug: 170405615
Test: atest CanControllerAidlTest
Test: manually test slcan and socketcan hardware
Change-Id: I06bbb1379f4385e89757722c0276009b54cc7255
diff --git a/automotive/can/aidl/default/CanBus.cpp b/automotive/can/aidl/default/CanBus.cpp
new file mode 100644
index 0000000..d1f9b78
--- /dev/null
+++ b/automotive/can/aidl/default/CanBus.cpp
@@ -0,0 +1,93 @@
+/*
+ * Copyright 2022, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "CanBus.h"
+
+#include <android-base/logging.h>
+#include <libnetdevice/libnetdevice.h>
+
+namespace aidl::android::hardware::automotive::can {
+
+CanBus::CanBus(std::string_view ifname) : mIfname(ifname) {}
+
+CanBus::~CanBus() {
+    std::lock_guard<std::mutex> lck(mIsUpGuard);
+    CHECK(!mIsUp) << "Interface is still up while being destroyed";
+}
+
+Result CanBus::preUp() {
+    return Result::OK;
+}
+
+bool CanBus::postDown() {
+    return true;
+}
+
+std::string CanBus::getIfaceName() {
+    return mIfname;
+}
+
+Result CanBus::up() {
+    std::lock_guard<std::mutex> lck(mIsUpGuard);
+
+    if (mIsUp) {
+        LOG(WARNING) << "Interface is already up";
+        return Result::INVALID_STATE;
+    }
+
+    const auto preResult = preUp();
+    if (preResult != Result::OK) return preResult;
+
+    const auto isUp = ::android::netdevice::isUp(mIfname);
+    if (!isUp.has_value()) {
+        // preUp() should prepare the interface (either create or make sure it's there)
+        LOG(ERROR) << "Interface " << mIfname << " didn't get prepared";
+        return Result::BAD_INTERFACE_ID;
+    }
+
+    if (!*isUp && !::android::netdevice::up(mIfname)) {
+        LOG(ERROR) << "Can't bring " << mIfname << " up";
+        return Result::UNKNOWN_ERROR;
+    }
+    mDownAfterUse = !*isUp;
+
+    mIsUp = true;
+    return Result::OK;
+}
+
+Result CanBus::down() {
+    std::lock_guard<std::mutex> lck(mIsUpGuard);
+
+    if (!mIsUp) {
+        LOG(WARNING) << "Interface is already down";
+        return Result::INVALID_STATE;
+    }
+    mIsUp = false;
+
+    Result success = Result::OK;
+
+    if (mDownAfterUse && !::android::netdevice::down(mIfname)) {
+        LOG(ERROR) << "Can't bring " << mIfname << " down";
+        // don't return yet, let's try to do best-effort cleanup
+        success = Result::UNKNOWN_ERROR;
+    }
+
+    if (!postDown()) success = Result::UNKNOWN_ERROR;
+
+    return success;
+}
+
+}  // namespace aidl::android::hardware::automotive::can