Subscribing to Address Sanitizer Events (C/C++)

Available APIs

For details about how to use the APIs (such as parameter usage restrictions and value ranges), see HiAppEvent.

Subscription APIs:

API	Description
int OH_HiAppEvent_AddWatcher (HiAppEvent_Watcher *watcher)	Adds a watcher to listen for application events.
int OH_HiAppEvent_RemoveWatcher (HiAppEvent_Watcher *watcher)	Removes a watcher for the specified application events.

How to Develop

The following describes how to subscribe an address sanitizer event for an array bounds write.

Create a native C++ project and import the jsoncpp file to the project. The directory structure is as follows:

entry:
  src:
    main:
      cpp:
        - json:
            - json.h
            - json-forwards.h
        - types:
            libentry:
              - index.d.ts
        - CMakeLists.txt
        - napi_init.cpp
        - jsoncpp.cpp
      ets:
        - entryability:
            - EntryAbility.ets
        - pages:
            - Index.ets

In the CMakeLists.txt file, add the source file and dynamic libraries.

# Add the **jsoncpp.cpp** file, which is used to parse the JSON strings in the subscription events.
add_library(entry SHARED napi_init.cpp jsoncpp.cpp)
# Add **libhiappevent_ndk.z.so** and **libhilog_ndk.z.so** (log output). 
target_link_libraries(entry PUBLIC libace_napi.z.so libhilog_ndk.z.so libhiappevent_ndk.z.so)

Import the dependencies to the napi_init.cpp file, and define LOG_TAG.

#include "napi/native_api.h"
#include "json/json.h"
#include "hilog/log.h"
#include "hiappevent/hiappevent.h"

#undef LOG_TAG
#define LOG_TAG "testTag"

Subscribe to system events.

Watcher of the onReceive type:

In the napi_init.cpp file, define the methods related to the watcher of the onReceive type.

// Define a variable to cache the pointer to the created watcher.
static HiAppEvent_Watcher *systemEventWatcher; 

static void OnReceive(const char *domain, const struct HiAppEvent_AppEventGroup *appEventGroups, uint32_t groupLen) {
    for (int i = 0; i < groupLen; ++i) {
        for (int j = 0; j < appEventGroups[i].infoLen; ++j) {
            OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.domain=%{public}s", appEventGroups[i].appEventInfos[j].domain);
            OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.name=%{public}s", appEventGroups[i].appEventInfos[j].name);
            OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.eventType=%{public}d", appEventGroups[i].appEventInfos[j].type);
            if (strcmp(appEventGroups[i].appEventInfos[j].domain, DOMAIN_OS) == 0 && 
                strcmp(appEventGroups[i].appEventInfos[j].name, EVENT_ADDRESS_SANITIZER) == 0) {
                Json::Value params;
                Json::Reader reader(Json::Features::strictMode());
                Json::FastWriter writer;
                if (reader.parse(appEventGroups[i].appEventInfos[j].params, params)) {
                    auto time = params["time"].asInt64();
                    auto bundleVersion = params["bundle_version"].asString();
                    auto bundleName = params["bundle_name"].asString();
                    auto pid = params["pid"].asInt();
                    auto uid = params["uid"].asInt();
                    auto type = params["type"].asString();
                    auto boolFlag = params["log_over_limit"].asBool();
                    std::string logOverLimit = params["log_over_limit"].asBool() ? "true" : "false";
                    auto externalLog = writer.write(params["external_log"]);
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.time=%{public}lld", time);
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_version=%{public}s", bundleVersion.c_str());
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_name=%{public}s", bundleName.c_str());
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.pid=%{public}d", pid);
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.uid=%{public}d", uid);
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.type=%{public}s", type.c_str());
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.external_log=%{public}s", externalLog.c_str());
                    OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.log_over_limit=%{public}s", logOverLimit.c_str());
                }
            }
        }
    }
}

static napi_value RegisterWatcher(napi_env env, napi_callback_info info) {
    // Set the watcher name. The system identifies different watchers based on their names.
    systemEventWatcher = OH_HiAppEvent_CreateWatcher("onReceiverWatcher");
    // Set the event to subscribe to EVENT_ADDRESS_SANITIZER.
    const char *names[] = {EVENT_ADDRESS_SANITIZER};
    // Add the events to watch, for example, system events.
    OH_HiAppEvent_SetAppEventFilter(systemEventWatcher, DOMAIN_OS, 0, names, 1);
    // Set the implemented callback. After receiving the event, the watcher immediately triggers the OnReceive callback.
    OH_HiAppEvent_SetWatcherOnReceive(systemEventWatcher, OnReceive);
    // Add a watcher to listen for the specified event.
    OH_HiAppEvent_AddWatcher(systemEventWatcher);
    return {};
}

Watcher of the onTrigger type:

In the napi_init.cpp file, define the methods related to the watcher of the OnTrigger type.

// Define a variable to cache the pointer to the created watcher.
static HiAppEvent_Watcher *systemEventWatcher;

// Implement the callback function used to return the listened events. The content pointed by the events pointer is valid only in this function.
static void OnTake(const char *const *events, uint32_t eventLen) {
    Json::Reader reader(Json::Features::strictMode());
    Json::FastWriter writer;
    for (int i = 0; i < eventLen; ++i) {
        Json::Value eventInfo;
        if (reader.parse(events[i], eventInfo)) {
            auto domain =  eventInfo["domain_"].asString();
            auto name = eventInfo["name_"].asString();
            auto type = eventInfo["type_"].asInt();
            OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.domain=%{public}s", domain.c_str());
            OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.name=%{public}s", name.c_str());
            OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.eventType=%{public}d", type);
            if (domain ==  DOMAIN_OS && name == EVENT_ADDRESS_SANITIZER) {
                auto time = eventInfo["time"].asInt64();
                auto bundleVersion = eventInfo["bundle_version"].asString();
                auto bundleName = eventInfo["bundle_name"].asString();
                auto pid = eventInfo["pid"].asInt();
                auto uid = eventInfo["uid"].asInt();
                auto asanType = eventInfo["type"].asString();
                auto externalLog = writer.write(eventInfo["external_log"]);
                std::string logOverLimit = eventInfo["log_over_limit"].asBool() ? "true" : "false";
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.time=%{public}lld", time);
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_version=%{public}s", bundleVersion.c_str());
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.bundle_name=%{public}s", bundleName.c_str());
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.pid=%{public}d", pid);
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.uid=%{public}d", uid);
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.crash_type=%{public}s", asanType.c_str());
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.external_log=%{public}s", externalLog.c_str());
                OH_LOG_INFO(LogType::LOG_APP, "HiAppEvent eventInfo.params.log_over_limit=%{public}s", logOverLimit.c_str());
            }
        }
    }
}

// Implement the subscription callback function to apply custom processing to the obtained event logging data.
static void OnTrigger(int row, int size) {
    // After the callback is received, obtain the specified number of received events.
    OH_HiAppEvent_TakeWatcherData(systemEventWatcher, row, OnTake);
}

static napi_value RegisterWatcher(napi_env env, napi_callback_info info) {
    // Set the watcher name. The system identifies different watchers based on their names.
    systemEventWatcher = OH_HiAppEvent_CreateWatcher("onTriggerWatcher");
    // Set the event to subscribe to EVENT_ADDRESS_SANITIZER.
    const char *names[] = {EVENT_ADDRESS_SANITIZER};
    // Add the events to watch, for example, system events.
    OH_HiAppEvent_SetAppEventFilter(systemEventWatcher, DOMAIN_OS, 0, names, 1);
    // Set the implemented callback function. The callback function will be triggered when the conditions set by OH_HiAppEvent_SetTriggerCondition are met.
    OH_HiAppEvent_SetWatcherOnTrigger(systemEventWatcher, OnTrigger);
    // Set the conditions for triggering the subscription callback. For example, trigger this onTrigger callback when the number of new event logs is 1.
    OH_HiAppEvent_SetTriggerCondition(systemEventWatcher, 1, 0, 0);
    // Add a watcher to listen for the specified event.
    OH_HiAppEvent_AddWatcher(systemEventWatcher);
    return {};
}

Construct an address out-of-bounds error.

In the napi_init.cpp file, define a Test method to perform out-of-bounds access on an integer array.
```
static napi_value Test(napi_env env, napi_callback_info info)
{
    int a[10];
    a[10] = 1;
    return {};
}
```

In the napi_init.cpp file, register RegisterWatcher and Test as ArkTS APIs.

static napi_value Init(napi_env env, napi_value exports)
{
    napi_property_descriptor desc[] = {
        { "registerWatcher", nullptr, RegisterWatcher, nullptr, nullptr, nullptr, napi_default, nullptr },
        { "test", nullptr, Test, nullptr, nullptr, nullptr, napi_default, nullptr}
    };
    napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
    return exports;
}

In the index.d.ts file, define ArkTS APIs.

export const registerWatcher: () => void;
export const test: () => void;

In the EntryAbility.ets file, add the following interface invocation to onCreate().

// Import the dependent module.
import testNapi from 'libentry.so'

// Add the interface invocation to onCreate().
// Register the system event watcher at startup.
testNapi.registerWatcher();

In the entry/src/main/ets/pages/Index.ets file, add a button to trigger the address sanitizer event.

import testNapi from 'libentry.so'

@Entry
@Component
struct Index {
  build() {
    Row() {
      Column() {
        Button("address-sanitizer").onClick(() => {
          testNapi.test();
        })
      }
      .width('100%')
    }
    .height('100%')
  }
}

In DevEco Studio, choose entry, click Edit Configurations, click Diagnostics, select Address Sanitizer, and click OK. Click the Run button to run the project. Then, click the address-sanitizer button to trigger an address sanitizer event. The application crashes. After restarting the application, you can view the following event information in the Log window.

HiAppEvent eventInfo.domain=OS
HiAppEvent eventInfo.name=ADDRESS_SANITIZER
HiAppEvent eventInfo.eventType=1
HiAppEvent eventInfo.params.time=1713148093326
HiAppEvent eventInfo.params.bundle_version=1.0.0
HiAppEvent eventInfo.params.bundle_name=com.example.myapplication
HiAppEvent eventInfo.params.pid=3378
HiAppEvent eventInfo.params.uid=20020140
HiAppEvent eventInfo.params.type="stack-buffer-overflow"
HiAppEvent eventInfo.params.external_log=["/data/storage/el2/log/hiappevent/ADDRESS_SANITIZER_1713148093326_3378.log"]
HiAppEvent eventInfo.params.log_over_limit=false

Remove the event watcher.

static napi_value RemoveWatcher(napi_env env, napi_callback_info info) {
    // Remove the watcher.
    OH_HiAppEvent_RemoveWatcher(systemEventWatcher);
    return {};
}

Destroy the event watcher.

static napi_value DestroyWatcher(napi_env env, napi_callback_info info) {
    // Destroy the created watcher and set systemEventWatcher to nullptr.
    OH_HiAppEvent_DestroyWatcher(systemEventWatcher);
    systemEventWatcher = nullptr;
    return {};
}