Android P update_engine分析 --update_engine_client的工作
Posted Give.Me.Five
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Android P update_engine分析 --update_engine_client的工作相关的知识，希望对你有一定的参考价值。
当AB系统升级时，有两种方式来调用updateengine,来实现升级，一种方法是直接执行shell命令，调用 update_engine_client，带参数来实现升级，另一种方式是应用层直接调用UpdateEngine的applyPayload方法来升级。
update_engine_client 带参升级
shell命令调用update_engine_client带参数去升级，具体如下：
update_engine_client --payload=file:///sdcard/payload.bin --update --headers="FILE_HASH=qeebzpLK4f/FaDAVJ9ilCxnUC/TMO16S5QP39AjsYKc=
FILE_SIZE=445814087
METADATA_HASH=nn9V2c3dQ3yHwQQJW0R0Q+y+OQzWuJ5FZt4HxCiAry0=
METADATA_SIZE=58898"
后面带了payload-file和 headers的参数，那我们来分析下update_engine_client 到底是如何来工作的。
int main(int argc, char** argv)
//初始化UpdateEngineClientandroid，然后执行
chromeos_update_engine::internal::UpdateEngineClientAndroid client(
argc, argv);
return client.Run();
class UpdateEngineClientAndroid : public brillo::Daemon
....
UpdateEngineClientAndroid 是继承brillo::Daemon的，这个类我们在启动update_engine里分析过，执行其Run函数时，会先调用 onInit（）, 那我们一起来看看onInit:
int UpdateEngineClientAndroid::OnInit()
int ret = Daemon::OnInit();
if (ret != EX_OK)
return ret;
//对后续参数的数据类型，默认值，以及参数解释
DEFINE_bool(update, false, "Start a new update, if no update in progress.");
DEFINE_string(payload,
"http://127.0.0.1:8080/payload",
"The URI to the update payload to use.");
DEFINE_int64(offset, 0,
"The offset in the payload where the CrAU update starts. "
"Used when --update is passed.");
DEFINE_int64(size, 0,
"The size of the CrAU part of the payload. If 0 is passed, it "
"will be autodetected. Used when --update is passed.");
DEFINE_string(headers,
"",
"A list of key-value pairs, one element of the list per line. "
"Used when --update is passed.");
DEFINE_bool(suspend, false, "Suspend an ongoing update and exit.");
DEFINE_bool(resume, false, "Resume a suspended update.");
DEFINE_bool(cancel, false, "Cancel the ongoing update and exit.");
DEFINE_bool(reset_status, false, "Reset an already applied update and exit.");
DEFINE_bool(follow,
false,
"Follow status update changes until a final state is reached. "
"Exit status is 0 if the update succeeded, and 1 otherwise.");
// 使用Brillo::FlagHelper来解析带的参数
base::CommandLine::Init(argc_, argv_);
brillo::FlagHelper::Init(argc_, argv_, "Android Update Engine Client");
if (argc_ == 1)
LOG(ERROR) << "Nothing to do. Run with --help for help.";
return 1;
// 检测参数的合法性
const std::vector<std::string> positional_args =
base::CommandLine::ForCurrentProcess()->GetArgs();
if (!positional_args.empty())
LOG(ERROR) << "Found a positional argument '" << positional_args.front()
<< "'. If you want to pass a value to a flag, pass it as "
"--flag=value.";
return 1;
//启动brillo的log系统
bool keep_running = false;
brillo::InitLog(brillo::kLogToStderr);
//启动一个binder的看门狗
binder_watcher_.Init();
//通过Binder获取UpdateEngineService的服务，并赋仠给service_
android::status_t status = android::getService(
android::String16("android.os.UpdateEngineService"), &service_);
if (status != android::OK)
LOG(ERROR) << "Failed to get IUpdateEngine binder from service manager: "
<< Status::fromStatusT(status).toString8();
return ExitWhenIdle(1);
//如果有接suspend的参数
if (FLAGS_suspend)
return ExitWhenIdle(service_->suspend());
//如果有接resume参数
if (FLAGS_resume)
return ExitWhenIdle(service_->resume());
//如果有接cancel参数
if (FLAGS_cancel)
return ExitWhenIdle(service_->cancel());
//如果有接reset_status参数
if (FLAGS_reset_status)
return ExitWhenIdle(service_->resetStatus());
//如果有接follow，注册一个回调
if (FLAGS_follow)
// Register a callback object with the service.
callback_ = new UECallback(this);
bool bound;
if (!service_->bind(callback_, &bound).isOk() || !bound)
LOG(ERROR) << "Failed to bind() the UpdateEngine daemon.";
return 1;
keep_running = true;
//如果有接update参数，解析分割headers参数
if (FLAGS_update)
std::vector<std::string> headers = base::SplitString(
FLAGS_headers, "\\n", base::KEEP_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
std::vector<android::String16> and_headers;
for (const auto& header : headers)
and_headers.push_back(android::String16header.data(), header.size());
//执行applyPayload函数，执行升级
Status status = service_->applyPayload(
android::String16FLAGS_payload.data(), FLAGS_payload.size(),
FLAGS_offset,
FLAGS_size,
and_headers);
if (!status.isOk())
return ExitWhenIdle(status);
if (!keep_running)
return ExitWhenIdle(EX_OK);
//监听service_状态的改变，如UpdateEngineServiceDied
android::BinderWrapper::Create();
android::BinderWrapper::Get()->RegisterForDeathNotifications(
android::os::IUpdateEngine::asBinder(service_),
base::Bind(&UpdateEngineClientAndroid::UpdateEngineServiceDied,
base::Unretained(this)));
return EX_OK;
从上面可以看到先定义参数的数据类型，检查其合法，解析参数，获取updateEngineService服务，然后执行其applyPayload。这个方式感觉UpdateEngine.applyPayload方式一样，具体是否一致呢，我们来看看UpdateEngine的applyPayload的实现。
UpdateEngine.applyPayload
public void applyPayload(String url, long offset, long size, String[] headerKeyValuePairs)
try
//调用 service的applyPayload
mUpdateEngine.applyPayload(url, offset, size, headerKeyValuePairs);
catch (RemoteException e)
throw e.rethrowFromSystemServer();
public UpdateEngine()
//mUpdateEngine 也是通过Binder获取update_engine service
mUpdateEngine = IUpdateEngine.Stub.asInterface(
ServiceManager.getService(UPDATE_ENGINE_SERVICE));
那我们猜的结果是一样，也是调用updateEngine服务的applyPayload。那升级的具体实现其实是调用applyPayload来实现的。
UpdateEngine服务
上面看到不管是update_engine_client 还是Java层的updateEngine接口，最后调用到都是updateEngine服务，对应到的是BinderUpdateEngineAndroidService：
class BinderUpdateEngineAndroidService : public android::os::BnUpdateEngine,
public ServiceObserverInterface
const char* ServiceName() const
return "android.os.UpdateEngineService";
Status BinderUpdateEngineAndroidService::applyPayload(
const android::String16& url,
int64_t payload_offset,
int64_t payload_size,
const std::vector<android::String16>& header_kv_pairs)
const std::string payload_urlandroid::String8url.string();
std::vector<std::string> str_headers;
str_headers.reserve(header_kv_pairs.size());
for (const auto& header : header_kv_pairs)
str_headers.emplace_back(android::String8header.string());
brillo::ErrorPtr error;
if (!service_delegate_->ApplyPayload(
payload_url, payload_offset, payload_size, str_headers, &error))
return ErrorPtrToStatus(error);
return Status::ok();
updateService 实际上的是service_delegate_，这个也是DaemonStateAndroid 获取的service_delegate，也就是update_attempter_.get()， 对应的类是UpdateAttempterAndroid。
bool UpdateAttempterAndroid::ApplyPayload(
const string& payload_url,
int64_t payload_offset,
int64_t payload_size,
const vector<string>& key_value_pair_headers,
brillo::ErrorPtr* error)
//如果需要升级，不能继续再升级了
if (status_ == UpdateStatus::UPDATED_NEED_REBOOT)
return LogAndSetError(
error, FROM_HERE, "An update already applied, waiting for reboot");
//如果在升级过程中，不能继续升级
if (ongoing_update_)
return LogAndSetError(
error, FROM_HERE, "Already processing an update, cancel it first.");
DCHECK(status_ == UpdateStatus::IDLE);
//将headers的参数解析出来后，添加到headers的maps中
std::map<string, string> headers;
for (const string& key_value_pair : key_value_pair_headers)
string key;
string value;
if (!brillo::string_utils::SplitAtFirst(
key_value_pair, "=", &key, &value, false))
return LogAndSetError(
error, FROM_HERE, "Passed invalid header: " + key_value_pair);
if (!headers.emplace(key, value).second)
return LogAndSetError(error, FROM_HERE, "Passed repeated key: " + key);
//设置一个对应的独一无二的id
string payload_id = (headers[kPayloadPropertyFileHash] +
headers[kPayloadPropertyMetadataHash]);
//初始化一个install_plan_， 然后将applyPayload的参数赋值给install_plan_。
install_plan_ = InstallPlan();
install_plan_.download_url = payload_url;
install_plan_.version = "";
base_offset_ = payload_offset;
InstallPlan::Payload payload;
payload.size = payload_size;
if (!payload.size)
if (!base::StringToUint64(headers[kPayloadPropertyFileSize],
&payload.size))
payload.size = 0;
if (!brillo::data_encoding::Base64Decode(headers[kPayloadPropertyFileHash],
&payload.hash))
LOG(WARNING) << "Unable to decode base64 file hash: "
<< headers[kPayloadPropertyFileHash];
if (!base::StringToUint64(headers[kPayloadPropertyMetadataSize],
&payload.metadata_size))
payload.metadata_size = 0;
// The |payload.type| is not used anymore since minor_version 3.
payload.type = InstallPayloadType::kUnknown;
install_plan_.payloads.push_back(payload);
// The |public_key_rsa| key would override the public key stored on disk.
install_plan_.public_key_rsa = "";
install_plan_.hash_checks_mandatory = hardware_->IsOfficialBuild();
install_plan_.is_resume = !payload_id.empty() &&
DeltaPerformer::CanResumeUpdate(prefs_, payload_id);
if (!install_plan_.is_resume)
if (!DeltaPerformer::ResetUpdateProgress(prefs_, false))
LOG(WARNING) << "Unable to reset the update progress.";
if (!prefs_->SetString(kPrefsUpdateCheckResponseHash, payload_id))
LOG(WARNING) << "Unable to save the update check response hash.";
install_plan_.source_slot = boot_control_->GetCurrentSlot();
install_plan_.target_slot = install_plan_.source_slot == 0 ? 1 : 0;
install_plan_.powerwash_required =
GetHeaderAsBool(headers[kPayloadPropertyPowerwash], false);
install_plan_.switch_slot_on_reboot =
GetHeaderAsBool(headers[kPayloadPropertySwitchSlotOnReboot], true);
install_plan_.run_post_install = true;
//判断是否可以设置run_post_install
if (install_plan_.is_resume && prefs_->Exists(kPrefsPostInstallSucceeded))
bool post_install_succeeded = false;
prefs_->GetBoolean(kPrefsPostInstallSucceeded, &post_install_succeeded);
if (post_install_succeeded)
install_plan_.run_post_install =
GetHeaderAsBool(headers[kPayloadPropertyRunPostInstall], true);
//检测网络id
NetworkId network_id = kDefaultNetworkId;
if (!headers[kPayloadPropertyNetworkId].empty())
if (!base::StringToUint64(headers[kPayloadPropertyNetworkId],
&network_id))
return LogAndSetError(
error,
FROM_HERE,
"Invalid network_id: " + headers[kPayloadPropertyNetworkId]);
if (!network_selector_->SetProcessNetwork(network_id))
return LogAndSetError(
error,
FROM_HERE,
"Unable to set network_id: " + headers[kPayloadPropertyNetworkId]);
//打印install_plan_的信息
LOG(INFO) << "Using this install plan:";
install_plan_.Dump();
//开启UpdateAction的动作，开启推动升级开始
BuildUpdateActions(payload_url);
//设置额外的校验头 和 用户代理的头
HttpFetcher* fetcher = download_action_->http_fetcher();
if (!headers[kPayloadPropertyAuthorization].empty())
fetcher->SetHeader("Authorization", headers[kPayloadPropertyAuthorization]);
if (!headers[kPayloadPropertyUserAgent].empty())
fetcher->SetHeader("User-Agent", headers[kPayloadPropertyUserAgent]);
//回调升级的状态
SetStatusAndNotify(UpdateStatus::UPDATE_AVAILABLE);
ongoing_update_ = true;
//升级之前，确认当前的bootFlags 已经 更新
UpdateBootFlags();
//更新本地存储的升级信息，包括 ，升级次数，重启次数，升级时间等
UpdatePrefsOnUpdateStart(install_plan_.is_resume);
return true;
从上面的注释里可以看到，先将applyPayload的相关信息与参数传给install_plan_的结构体中，然后调用BuildUpdateActions去开启升级。那下面我们继续分析BuildUpdateActions(payload_url)。
void UpdateAttempterAndroid::BuildUpdateActions(const string& url)
CHECK(!processor_->IsRunning());
processor_->set_delegate(this);
//初始化InstallPlanAction的升级安装行动
shared_ptr<InstallPlanAction> install_plan_action(
new InstallPlanAction(install_plan_));
HttpFetcher* download_fetcher = nullptr;
if (FileFetcher::SupportedUrl(url))
DLOG(INFO) << "Using FileFetcher for file URL.";
download_fetcher = new FileFetcher();
else
#ifdef _UE_SIDELOAD
LOG(FATAL) << "Unsupported sideload URI: " << url;
#else
LibcurlHttpFetcher* libcurl_fetcher =
new LibcurlHttpFetcher(&proxy_resolver_,<以上是关于Android P update_engine分析 --update_engine_client的工作的主要内容，如果未能解决你的问题，请参考以下文章
Android P update_engine分析--升级核心DeltaPerformer的分析
Android P update_engine分析--升级核心DeltaPerformer的分析
Android P update_engine分析--升级核心DeltaPerformer的分析
Android P update_engine分析--升级核心DeltaPerformer的分析