android 系统复位（Reset 恢复出厂设置）9.0源码分析

今天来从源码的角度分析一下android 系统复位的流程

1. 从点击 Reset 看起。点击Reset后，会弹出Erase everything。故而从在Setting中搜索此字段开始。

因为我这里面有TV项目，也有手机项目。这里就看手机项目，即“master_clear_final_button_text”字段。

packages\apps\Settings\res\layout\master_clear_confirm.xml

接下来找这个button 的点击事件。

packages\apps\Settings\src\com\android\settings\MasterClearConfirm.java
public class MasterClearConfirm extends InstrumentedFragment {private View mContentView;private boolean mEraseSdCard;private boolean mEraseEsims;/*** The user has gone through the multiple confirmation, so now we go ahead* and invoke the Checkin Service to reset the device to its factory-default* state (rebooting in the process).*/private Button.OnClickListener mFinalClickListener = new Button.OnClickListener() {public void onClick(View v) {if (Utils.isMonkeyRunning()) {return;}final PersistentDataBlockManager pdbManager = (PersistentDataBlockManager)getActivity().getSystemService(Context.PERSISTENT_DATA_BLOCK_SERVICE);final OemLockManager oemLockManager = (OemLockManager)getActivity().getSystemService(Context.OEM_LOCK_SERVICE);if (pdbManager != null && !oemLockManager.isOemUnlockAllowed() &&Utils.isDeviceProvisioned(getActivity())) {// if OEM unlock is allowed, the persistent data block will be wiped during FR// process. If disabled, it will be wiped here, unless the device is still being// provisioned, in which case the persistent data block will be preserved.new AsyncTask<Void, Void, Void>() {int mOldOrientation;ProgressDialog mProgressDialog;@Overrideprotected Void doInBackground(Void... params) {pdbManager.wipe();return null;}@Overrideprotected void onPostExecute(Void aVoid) {mProgressDialog.hide();if (getActivity() != null) {getActivity().setRequestedOrientation(mOldOrientation);doMasterClear();    //  点击后此方法}}@Overrideprotected void onPreExecute() {mProgressDialog = getProgressDialog();mProgressDialog.show();   // 执行时 转圈等待// need to prevent orientation changes as we're about to go into// a long IO request, so we won't be able to access inflate resources on flashmOldOrientation = getActivity().getRequestedOrientation();getActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LOCKED);}}.execute();} else {doMasterClear();}}private ProgressDialog getProgressDialog() {final ProgressDialog progressDialog = new ProgressDialog(getActivity());progressDialog.setIndeterminate(true);progressDialog.setCancelable(false);progressDialog.setTitle(getActivity().getString(R.string.master_clear_progress_title));progressDialog.setMessage(getActivity().getString(R.string.master_clear_progress_text));return progressDialog;}};private void doMasterClear() {   //  重点是这个方法，其实是发送了一个广播。Intent intent = new Intent(Intent.ACTION_FACTORY_RESET);//intent.setPackage("android");intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);intent.putExtra(Intent.EXTRA_REASON, "MasterClearConfirm");intent.putExtra(Intent.EXTRA_WIPE_EXTERNAL_STORAGE, mEraseSdCard);intent.putExtra(Intent.EXTRA_WIPE_ESIMS, mEraseEsims);getActivity().sendBroadcast(intent);  // Intent handling is asynchronous -- assume it will happen soon.}/*** Configure the UI for the final confirmation interaction*/private void establishFinalConfirmationState() {mContentView.findViewById(R.id.execute_master_clear).setOnClickListener(mFinalClickListener);}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {final EnforcedAdmin admin = RestrictedLockUtils.checkIfRestrictionEnforced(getActivity(), UserManager.DISALLOW_FACTORY_RESET, UserHandle.myUserId());if (RestrictedLockUtils.hasBaseUserRestriction(getActivity(),UserManager.DISALLOW_FACTORY_RESET, UserHandle.myUserId())) {return inflater.inflate(R.layout.master_clear_disallowed_screen, null);} else if (admin != null) {new ActionDisabledByAdminDialogHelper(getActivity()).prepareDialogBuilder(UserManager.DISALLOW_FACTORY_RESET, admin).setOnDismissListener(__ -> getActivity().finish()).show();return new View(getActivity());}mContentView = inflater.inflate(R.layout.master_clear_confirm, null);establishFinalConfirmationState();setAccessibilityTitle();return mContentView;}private void setAccessibilityTitle() {CharSequence currentTitle = getActivity().getTitle();TextView confirmationMessage =(TextView) mContentView.findViewById(R.id.master_clear_confirm);if (confirmationMessage != null) {String accessibleText = new StringBuilder(currentTitle).append(",").append(confirmationMessage.getText()).toString();getActivity().setTitle(Utils.createAccessibleSequence(currentTitle, accessibleText));}}@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);Bundle args = getArguments();mEraseSdCard = args != null&& args.getBoolean(MasterClear.ERASE_EXTERNAL_EXTRA);mEraseEsims = args != null&& args.getBoolean(MasterClear.ERASE_ESIMS_EXTRA);}@Overridepublic int getMetricsCategory() {return MetricsEvent.MASTER_CLEAR_CONFIRM;}
}

从上面可以看出，用户点击reset 后，其实是发送了一个名为ACTION_FACTORY_RESET（android.intent.action.FACTORY_RESET）的广播。这里值得注意的是：以前的广播为android.intent.action.MASTER_CLEAR，但是已经被ACTION_FACTORY_RESET 替换

 /*** Deprecated - use ACTION_FACTORY_RESET instead.* @hide* @removed*/
@Deprecated
@SystemApi
public static final String ACTION_MASTER_CLEAR = "android.intent.action.MASTER_CLEAR";

2. 接下来查找接受这个广播的地方，通过全局grep 搜索。得到:

 frameworks/base/services/core/java/com/android/server/MasterClearReceiver.javapublic class MasterClearReceiver extends BroadcastReceiver {private static final String TAG = "MasterClear";private boolean mWipeExternalStorage;private boolean mWipeEsims;@Overridepublic void onReceive(final Context context, final Intent intent) {if (intent.getAction().equals(Intent.ACTION_REMOTE_INTENT)) {if (!"google.com".equals(intent.getStringExtra("from"))) {Slog.w(TAG, "Ignoring master clear request -- not from trusted server.");return;}}if (Intent.ACTION_MASTER_CLEAR.equals(intent.getAction())) {Slog.w(TAG, "The request uses the deprecated Intent#ACTION_MASTER_CLEAR, "+ "Intent#ACTION_FACTORY_RESET should be used instead.");//这里都在说 广播都替换了}if (intent.hasExtra(Intent.EXTRA_FORCE_MASTER_CLEAR)) {Slog.w(TAG, "The request uses the deprecated Intent#EXTRA_FORCE_MASTER_CLEAR, "+ "Intent#EXTRA_FORCE_FACTORY_RESET should be used instead.");}final boolean shutdown = intent.getBooleanExtra("shutdown", false);final String reason = intent.getStringExtra(Intent.EXTRA_REASON);mWipeExternalStorage = intent.getBooleanExtra(Intent.EXTRA_WIPE_EXTERNAL_STORAGE, false);mWipeEsims = intent.getBooleanExtra(Intent.EXTRA_WIPE_ESIMS, false);final boolean forceWipe = intent.getBooleanExtra(Intent.EXTRA_FORCE_MASTER_CLEAR, false)|| intent.getBooleanExtra(Intent.EXTRA_FORCE_FACTORY_RESET, false);// 发广播时传过来的参数Slog.w(TAG, "!!! FACTORY RESET !!!");// The reboot call is blocking, so we need to do it on another thread.Thread thr = new Thread("Reboot") {@Overridepublic void run() {try {RecoverySystem.rebootWipeUserData(context, shutdown, reason, forceWipe, mWipeEsims);//重点，准备做重启擦除用户数据的动作。Log.wtf(TAG, "Still running after master clear?!");} catch (IOException e) {Slog.e(TAG, "Can't perform master clear/factory reset", e);} catch (SecurityException e) {Slog.e(TAG, "Can't perform master clear/factory reset", e);}}};if (mWipeExternalStorage || mWipeEsims) { // 如果传过来 这个参数为true的话，则进行清除SD的操作。// thr will be started at the end of this task.new WipeDataTask(context, thr).execute();} else {thr.start();}}private class WipeDataTask extends AsyncTask<Void, Void, Void> { // 利用AsyncTask 清除SD数据。默认不清除private final Thread mChainedTask;private final Context mContext;private final ProgressDialog mProgressDialog;public WipeDataTask(Context context, Thread chainedTask) {mContext = context;mChainedTask = chainedTask;mProgressDialog = new ProgressDialog(context);}@Overrideprotected void onPreExecute() {mProgressDialog.setIndeterminate(true);mProgressDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);mProgressDialog.setMessage(mContext.getText(R.string.progress_erasing));mProgressDialog.show();}@Overrideprotected Void doInBackground(Void... params) {Slog.w(TAG, "Wiping adoptable disks");if (mWipeExternalStorage) {StorageManager sm = (StorageManager) mContext.getSystemService(Context.STORAGE_SERVICE);sm.wipeAdoptableDisks();}return null;}@Overrideprotected void onPostExecute(Void result) {mProgressDialog.dismiss();mChainedTask.start();}}}

3.RecoverySystem.java 中rebootWipeUserData 方法，擦除用户数据

 frameworks\base\core\java\android\os\RecoverySystem.java/*** Reboots the device and wipes the user data and cache* partitions.  This is sometimes called a "factory reset", which* is something of a misnomer because the system partition is not* restored to its factory state.  Requires the* {@link android.Manifest.permission#REBOOT} permission.** @param context   the Context to use* @param shutdown  if true, the device will be powered down after*                  the wipe completes, rather than being rebooted*                  back to the regular system.* @param reason    the reason for the wipe that is visible in the logs* @param force     whether the {@link UserManager.DISALLOW_FACTORY_RESET} user restriction*                  should be ignored* @param wipeEuicc whether wipe the euicc data** @throws IOException  if writing the recovery command file* fails, or if the reboot itself fails.* @throws SecurityException if the current user is not allowed to wipe data.** @hide*/public static void rebootWipeUserData(Context context, boolean shutdown, String reason,boolean force, boolean wipeEuicc) throws IOException {UserManager um = (UserManager) context.getSystemService(Context.USER_SERVICE);if (!force && um.hasUserRestriction(UserManager.DISALLOW_FACTORY_RESET)) {throw new SecurityException("Wiping data is not allowed for this user.");}final ConditionVariable condition = new ConditionVariable();Intent intent = new Intent("android.intent.action.MASTER_CLEAR_NOTIFICATION");// 发送一个广播，厂商可以使用这个广播做一些客制化的操作。intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND| Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);context.sendOrderedBroadcastAsUser(intent, UserHandle.SYSTEM,android.Manifest.permission.MASTER_CLEAR,new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {condition.open();}}, null, 0, null, null);// Block until the ordered broadcast has completed.condition.block();if (wipeEuicc) {wipeEuiccData(context, PACKAGE_NAME_WIPING_EUICC_DATA_CALLBACK);}String shutdownArg = null;if (shutdown) {shutdownArg = "--shutdown_after";}String reasonArg = null;if (!TextUtils.isEmpty(reason)) {reasonArg = "--reason=" + sanitizeArg(reason);}final String localeArg = "--locale=" + Locale.getDefault().toLanguageTag() ;bootCommand(context, shutdownArg, "--wipe_data", reasonArg, localeArg);//重点是这个方法，将一些重要的字段信息保存起来}

bootCommand方法

 /*** Reboot into the recovery system with the supplied argument.* @param args to pass to the recovery utility.* @throws IOException if something goes wrong.*/private static void bootCommand(Context context, String... args) throws IOException {LOG_FILE.delete();StringBuilder command = new StringBuilder();for (String arg : args) {if (!TextUtils.isEmpty(arg)) {command.append(arg);command.append("\n");// 将字段命令拼接起来}}// Write the command into BCB (bootloader control block) and boot from// there. Will not return unless failed.RecoverySystem rs = (RecoverySystem) context.getSystemService(Context.RECOVERY_SERVICE);rs.rebootRecoveryWithCommand(command.toString());//throw new IOException("Reboot failed (no permissions?)");}

4. 调用系统服务 RecoverySystemService.java

frameworks\base\services\core\java\com\android\server\RecoverySystemService.java@Override // Binder callpublic void rebootRecoveryWithCommand(String command) {if (DEBUG) Slog.d(TAG, "rebootRecoveryWithCommand: [" + command + "]");synchronized (sRequestLock) {if (!setupOrClearBcb(true, command)) {return;}// Having set up the BCB, go ahead and reboot.PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);pm.reboot(PowerManager.REBOOT_RECOVERY);}}private boolean setupOrClearBcb(boolean isSetup, String command) {mContext.enforceCallingOrSelfPermission(android.Manifest.permission.RECOVERY, null);final boolean available = checkAndWaitForUncryptService();if (!available) {Slog.e(TAG, "uncrypt service is unavailable.");return false;}if (isSetup) {SystemProperties.set("ctl.start", "setup-bcb");} else {SystemProperties.set("ctl.start", "clear-bcb");}// Connect to the uncrypt service socket.LocalSocket socket = connectService();if (socket == null) {Slog.e(TAG, "Failed to connect to uncrypt socket");return false;}DataInputStream dis = null;DataOutputStream dos = null;try {dis = new DataInputStream(socket.getInputStream());dos = new DataOutputStream(socket.getOutputStream());// Send the BCB commands if it's to setup BCB.if (isSetup) {byte[] cmdUtf8 = command.getBytes("UTF-8");dos.writeInt(cmdUtf8.length);dos.write(cmdUtf8, 0, cmdUtf8.length);dos.flush();}// Read the status from the socket.int status = dis.readInt();// Ack receipt of the status code. uncrypt waits for the ack so// the socket won't be destroyed before we receive the code.dos.writeInt(0);if (status == 100) {Slog.i(TAG, "uncrypt " + (isSetup ? "setup" : "clear") +" bcb successfully finished.");} else {// Error in /system/bin/uncrypt.Slog.e(TAG, "uncrypt failed with status: " + status);return false;}} catch (IOException e) {Slog.e(TAG, "IOException when communicating with uncrypt:", e);return false;} finally {IoUtils.closeQuietly(dis);IoUtils.closeQuietly(dos);IoUtils.closeQuietly(socket);}return true;}

5.通过PowerManager 进行重启，重启流程可参见android系统关机源码（9.0）流程分析

这里有非常重要的一点：
在执行重启的时候，最终会走到以下的方法中：

frameworks\base\services\core\java\com\android\server\power\PowerManagerService.java/*** Low-level function to reboot the device. On success, this* function doesn't return. If more than 20 seconds passes from* the time a reboot is requested, this method returns.** @param reason code to pass to the kernel (e.g. "recovery"), or null.*/public static void lowLevelReboot(String reason) {if (reason == null) {reason = "";}// If the reason is "quiescent", it means that the boot process should proceed// without turning on the screen/lights.// The "quiescent" property is sticky, meaning that any number// of subsequent reboots should honor the property until it is reset.if (reason.equals(PowerManager.REBOOT_QUIESCENT)) {sQuiescent = true;reason = "";} else if (reason.endsWith("," + PowerManager.REBOOT_QUIESCENT)) {sQuiescent = true;reason = reason.substring(0,reason.length() - PowerManager.REBOOT_QUIESCENT.length() - 1);}if (reason.equals(PowerManager.REBOOT_RECOVERY)|| reason.equals(PowerManager.REBOOT_RECOVERY_UPDATE)) {reason = "recovery";   //走这个，reason为 recovery}if (sQuiescent) {// Pass the optional "quiescent" argument to the bootloader to let it know// that it should not turn the screen/lights on.reason = reason + ",quiescent";}SystemProperties.set("sys.powerctl", "reboot," + reason);//通过设置reason的属性，则重启开机后，会进入到recovery 模式，进行清除数据try {Thread.sleep(20 * 1000L);} catch (InterruptedException e) {Thread.currentThread().interrupt();}Slog.wtf(TAG, "Unexpected return from lowLevelReboot!");}

到此，android 系统复位的流程就分析完毕。总结一下：

恢复出厂设置总结：
1、在MasterClearConfirm.java中确认开始执行恢复出厂设置操作，并发出"恢复出厂设置"的广播;
2、在MasterClearReceiver.java接收MasterClearConfirm.java发出的广播，根据是否清除sdcard选项来执行相应的操作;
3、调用RecoverySystem.rebootWipeUserData()方法来清除用户数据并重启设备;这个方法执行过程中会发出"android.intent.action.MASTER_CLEAR_NOTIFICATION"广播、写"/cache/recovery/command"文件(内容包含"--wipe_data")，然后重启设备;
4、设备重启后进入recovery mode之后，读取/cache/recovery/command, 內容为"--wipe_data";
5.按照读取的command，进行wipe data清除数据操作;
6.清除成功后，系统重启，然后进入正常开机流程。

参考博客：
Android6.0 Reset恢复出厂设置流程分析

android 系统复位（Reset 恢复出厂设置）9.0源码分析相关推荐

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android 系统复位（Reset 恢复出厂设置）9.0源码分析

今天来从源码的角度分析一下android 系统复位的流程

1. 从点击 Reset 看起。点击Reset后，会弹出Erase everything。故而从在Setting中搜索此字段开始。

2. 接下来查找接受这个广播的地方，通过全局grep 搜索。得到:

3.RecoverySystem.java 中rebootWipeUserData 方法，擦除用户数据

4. 调用系统服务 RecoverySystemService.java

5.通过PowerManager 进行重启，重启流程可参见android系统关机源码（9.0）流程分析

android 系统复位（Reset 恢复出厂设置）9.0源码分析相关推荐

最新文章

热门文章

android 系统复位（Reset 恢复出厂设置）9.0源码分析

今天来从源码的角度 分析一下android 系统复位的流程

1. 从点击 Reset 看起。点击Reset后，会弹出Erase everything。故而从在Setting中搜索此字段开始。

2. 接下来查找接受这个广播的地方，通过全局grep 搜索 。得到:

3.RecoverySystem.java 中rebootWipeUserData 方法，擦除用户数据

4. 调用系统服务 RecoverySystemService.java

5.通过PowerManager 进行重启，重启流程可参见android系统关机源码（9.0）流程分析

android 系统复位（Reset 恢复出厂设置）9.0源码分析相关推荐

最新文章

热门文章

今天来从源码的角度分析一下android 系统复位的流程

2. 接下来查找接受这个广播的地方，通过全局grep 搜索。得到: