Implement CAN bus HAL tools

These tools are for manual interaction with CAN bus HAL instances.
Meant primarily for testing/debugging, not useful in user builds.

Bug: 135918744
Test: adb shell <tool name>
Change-Id: I1dfbe94c0006f69954806c395cd888f3bf2a4249
diff --git a/automotive/can/1.0/tools/canhaldump.cpp b/automotive/can/1.0/tools/canhaldump.cpp
new file mode 100644
index 0000000..5713d17
--- /dev/null
+++ b/automotive/can/1.0/tools/canhaldump.cpp
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2019 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 <android-base/logging.h>
+#include <android/hardware/automotive/can/1.0/ICanBus.h>
+#include <android/hardware/automotive/can/1.0/ICanMessageListener.h>
+#include <android/hidl/manager/1.2/IServiceManager.h>
+#include <hidl-utils/hidl-utils.h>
+
+#include <chrono>
+#include <iomanip>
+#include <iostream>
+#include <string>
+#include <thread>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace can {
+
+using namespace std::chrono_literals;
+
+using ICanBus = V1_0::ICanBus;
+using Result = V1_0::Result;
+
+struct CanMessageListener : public V1_0::ICanMessageListener {
+    const std::string name;
+
+    CanMessageListener(std::string name) : name(name) {}
+
+    virtual Return<void> onReceive(const V1_0::CanMessage& message) {
+        std::cout << "  " << name << "  " << std::hex << std::uppercase << std::setw(3)
+                  << std::setfill('0') << message.id << std::setw(0);
+        if (message.remoteTransmissionRequest) {
+            std::cout << " RTR";
+        } else {
+            std::cout << "   [" << message.payload.size() << "] ";
+            for (const auto byte : message.payload) {
+                std::cout << " " << unsigned(byte);
+            }
+        }
+        std::cout << std::nouppercase << std::dec << std::endl;
+        return {};
+    }
+
+    virtual Return<void> onError(V1_0::ErrorEvent error) {
+        std::cout << "  " << name << "  " << toString(error) << std::endl;
+        return {};
+    }
+};
+
+static void usage() {
+    std::cerr << "canhaldump - dump CAN bus traffic" << std::endl;
+    std::cerr << std::endl << "usage:" << std::endl << std::endl;
+    std::cerr << "canhaldump <bus name>" << std::endl;
+    std::cerr << "where:" << std::endl;
+    std::cerr << " bus name - name under which ICanBus is be published" << std::endl;
+}
+
+// TODO(b/135918744): extract to a new library
+static sp<ICanBus> tryOpen(const std::string& busname) {
+    auto bus = ICanBus::tryGetService(busname);
+    if (bus != nullptr) return bus;
+
+    /* Fallback for interfaces not registered in manifest. For testing purposes only,
+     * one should not depend on this in production deployment. */
+    auto manager = hidl::manager::V1_2::IServiceManager::getService();
+    auto ret = manager->get(ICanBus::descriptor, busname).withDefault(nullptr);
+    if (ret == nullptr) return nullptr;
+
+    std::cerr << "WARNING: bus " << busname << " is not registered in device manifest, "
+              << "trying to fetch it directly..." << std::endl;
+
+    return ICanBus::castFrom(ret);
+}
+
+static int candump(const std::string& busname) {
+    auto bus = tryOpen(busname);
+    if (bus == nullptr) {
+        std::cerr << "Bus " << busname << " is not available" << std::endl;
+        return -1;
+    }
+
+    Result result;
+    sp<V1_0::ICloseHandle> chnd;
+    // TODO(b/135918744): extract to library
+    bus->listen({}, new CanMessageListener(busname), hidl_utils::fill(&result, &chnd)).assertOk();
+
+    if (result != Result::OK) {
+        std::cerr << "Listen call failed: " << toString(result) << std::endl;
+        return -1;
+    }
+
+    while (true) std::this_thread::sleep_for(1h);
+}
+
+static int main(int argc, char* argv[]) {
+    base::SetDefaultTag("CanHalDump");
+    base::SetMinimumLogSeverity(android::base::VERBOSE);
+
+    if (argc == 0) {
+        usage();
+        return 0;
+    }
+
+    if (argc != 1) {
+        std::cerr << "Invalid number of arguments" << std::endl;
+        usage();
+        return -1;
+    }
+
+    return candump(argv[0]);
+}
+
+}  // namespace can
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android
+
+int main(int argc, char* argv[]) {
+    if (argc < 1) return -1;
+    return ::android::hardware::automotive::can::main(--argc, ++argv);
+}