android恢复出厂设置

http://www.tuicool.com/articles/Zj6jum
最近看恢复出厂的一个问题，以前也查过这方面的流程，所以这里整理一些AP+framework层的流程；
在setting-->备份与重置--->恢复出厂设置--->重置手机--->清除全部内容--->手机关机--->开机--->进行恢复出厂的操作--->开机流程；
下面回复出厂设置的整个过程:
(1)在settings中回复出厂设置的清楚按钮,直接到清除全部内容这个按钮的操作，
    对应的java类是setting中的MasterClearConfirm.java这个类，
private Button.OnClickListener mFinalClickListener = new Button.OnClickListener() {
public void onClick(View v) {
if (Utils.isMonkeyRunning()) {
return;
}

if (mEraseSdCard) {
Intent intent = new Intent(ExternalStorageFormatter.FORMAT_AND_FACTORY_RESET);
intent.setComponent(ExternalStorageFormatter.COMPONENT_NAME);
getActivity().startService(intent);
} else {
getActivity().sendBroadcast(new Intent("android.intent.action.MASTER_CLEAR"));
// Intent handling is asynchronous -- assume it will happen soon.
}
}
};
通过上述的代码，可以看出，实际上点击清除全部内容的时候，如果前面勾选上格式哈SD卡，就会执行mEraseSdCard为true里面的逻辑，如果没有勾选，就执行mEraseSdCard=false的逻辑，其实就是发送一个广播， “android.intent.action.MASTER_CLEAR”
(2)这个广播接受的地方，参见AndroidManifest.xml中的代码，如下：
<receiver android:name="com.android.server.MasterClearReceiver"
android:permission="android.permission.MASTER_CLEAR"
android:priority="100" >
<intent-filter>
<!-- For Checkin, Settings, etc.: action=MASTER_CLEAR -->
<action android:name="android.intent.action.MASTER_CLEAR" />

<!-- MCS always uses REMOTE_INTENT: category=MASTER_CLEAR -->
<action android:name="com.google.android.c2dm.intent.RECEIVE" />
<category android:name="android.intent.category.MASTER_CLEAR" />
</intent-filter>
</receiver>
找这个MasterClearReceiver.java这个receiver，下面来看看这个onReceiver()里面做了什么操作：
public 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;
}
}

Slog.w(TAG, "!!! FACTORY RESET !!!");
// The reboot call is blocking, so we need to do it on another thread.
Thread thr = new Thread("Reboot") {
@Override
public void run() {
try {
RecoverySystem.rebootWipeUserData(context);
Log.wtf(TAG, "Still running after master clear?!");
} catch (IOException e) {
Slog.e(TAG, "Can't perform master clear/factory reset", e);
}
}
};
thr.start();
}
这个里面主要的操作是：RecoverySystem.rebootWipeUserData(context);
准备做重启的动作，告诉手机要清除userData的数据；
(3)接着来看看RecoverySystem.rebootWipeUserData（）这个方法做了哪些操作：
public static void rebootWipeUserData(Context context) throws IOException {
final ConditionVariable condition = new ConditionVariable();

Intent intent = new Intent("android.intent.action.MASTER_CLEAR_NOTIFICATION");
context.sendOrderedBroadcastAsUser(intent, UserHandle.OWNER,
android.Manifest.permission.MASTER_CLEAR,
new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
condition.open();
}
}, null, 0, null, null);

// Block until the ordered broadcast has completed.
condition.block();

bootCommand(context, "--wipe_data\n--locale=" + Locale.getDefault().toString());
}
这个里面的广播可以先忽略不计，重点来看看bootCommand（）这个方法，注意这个参数“--wipe_data\n--locale=” ,此时将这个参数写入到/cache/recovery/command文件中,在以后进入recovery模式中时,要读取的参数,根据这些参数在执行
private static void bootCommand(Context context, String arg) throws IOException {
RECOVERY_DIR.mkdirs(); // In case we need it
COMMAND_FILE.delete(); // In case it's not writable
LOG_FILE.delete();

FileWriter command = new FileWriter(COMMAND_FILE);
try {
command.write(arg);
command.write("\n");
} finally {
command.close();
}

// Having written the command file, go ahead and reboot
PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
pm.reboot("recovery");

throw new IOException("Reboot failed (no permissions?)");
}
这个方法的操作大致是“写节点/cache/recovery/command”，把传递过来的字符串写进去；然后调用PowerManager进行重启操作，reboot（）；
(4)接着我们来看看PowerManager的reboot方法做了哪些操作：
public void reboot(String reason) {
try {
mService.reboot(false, reason, true);
} catch (RemoteException e) {
}
}
这个调用到了PowerManagerService.java这个类的reboot方法中了：
@Override // Binder call
public void reboot(boolean confirm, String reason, boolean wait) {
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.REBOOT, null);

final long ident = Binder.clearCallingIdentity();
try {
shutdownOrRebootInternal(false, confirm, reason, wait);
} finally {
Binder.restoreCallingIdentity(ident);
}
}
重点来看看shutdownOrRebootInternal（）这个方法，
private void shutdownOrRebootInternal(final boolean shutdown, final boolean confirm,
final String reason, boolean wait) {
if (mHandler == null || !mSystemReady) {
throw new IllegalStateException("Too early to call shutdown() or reboot()");
}

Runnable runnable = new Runnable() {
@Override
public void run() {
synchronized (this) {
if (shutdown) {
ShutdownThread.shutdown(mContext, confirm);
} else {
ShutdownThread.reboot(mContext, reason, confirm);
}
}
}
};

// ShutdownThread must run on a looper capable of displaying the UI.
Message msg = Message.obtain(mHandler, runnable);
msg.setAsynchronous(true);
mHandler.sendMessage(msg);

// PowerManager.reboot() is documented not to return so just wait for the inevitable.
if (wait) {
synchronized (runnable) {
while (true) {
try {
runnable.wait();
} catch (InterruptedException e) {
}
}
}
}
}
由于传递过来的shutdown为false，所以执行ShutdownThread.reboot(mContext, reason, confirm);reason：recevory 下面调用到ShutdownThread
(5) 这个追踪ShutdownThread.reboot()这个方法， 来窥视一下这个类：
public static void reboot(final Context context, String reason, boolean confirm) {
mReboot = true;
mRebootSafeMode = false;
mRebootReason = reason;
Log.d(TAG, "reboot");
shutdownInner(context, confirm);
}
这个里面做的操作就是给这个变量mRebootReason复制“recevory”，重点调用shutdownInner（）这个方法；
static void shutdownInner(final Context context, boolean confirm) {
// ensure that only one thread is trying to power down.
// any additional calls are just returned
synchronized (sIsStartedGuard) {
if (sIsStarted) {
Log.d(TAG, "Request to shutdown already running, returning.");
return;
}
}

Log.d(TAG, "Notifying thread to start radio shutdown");
bConfirmForAnimation = confirm;
final int longPressBehavior = context.getResources().getInteger(
com.android.internal.R.integer.config_longPressOnPowerBehavior);
final int resourceId = mRebootSafeMode
? com.android.internal.R.string.reboot_safemode_confirm
: (longPressBehavior == 2
? com.android.internal.R.string.shutdown_confirm_question
: com.android.internal.R.string.shutdown_confirm);

Log.d(TAG, "Notifying thread to start shutdown longPressBehavior=" + longPressBehavior);

if (confirm) {
final CloseDialogReceiver closer = new CloseDialogReceiver(context);
if (sConfirmDialog != null) {
sConfirmDialog.dismiss();
}
if (sConfirmDialog == null) {
Log.d(TAG, "PowerOff dialog doesn't exist. Create it first");
sConfirmDialog = new AlertDialog.Builder(context)
.setTitle(mRebootSafeMode
? com.android.internal.R.string.reboot_safemode_title
: com.android.internal.R.string.power_off)
.setMessage(resourceId)
.setPositiveButton(com.android.internal.R.string.yes, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
beginShutdownSequence(context);
if (sConfirmDialog != null) {
sConfirmDialog = null;
}
}
})
.setNegativeButton(com.android.internal.R.string.no, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
synchronized (sIsStartedGuard) {
sIsStarted = false;
}
if (sConfirmDialog != null) {
sConfirmDialog = null;
}
}
})
.create();
sConfirmDialog.setCancelable(false);//blocking back key
sConfirmDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
/*if (!context.getResources().getBoolean(
com.android.internal.R.bool.config_sf_slowBlur)) {
sConfirmDialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
}*/
/* To fix video+UI+blur flick issue */
sConfirmDialog.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
}

closer.dialog = sConfirmDialog;
sConfirmDialog.setOnDismissListener(closer);

if (!sConfirmDialog.isShowing()) {
sConfirmDialog.show();
}
} else {
beginShutdownSequence(context);
}
}
看beginShutdownSequence（）这个方法吧，重点调用到这个方法里面去了，来瞅瞅这个方法：
private static void beginShutdownSequence(Context context) {
synchronized (sIsStartedGuard) {
if (sIsStarted) {
Log.e(TAG, "ShutdownThread is already running, returning.");
return;
}
sIsStarted = true;
}

// start the thread that initiates shutdown
sInstance.mContext = context;
sInstance.mPowerManager = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
sInstance.mHandler = new Handler() {
};

bPlayaudio = true;
if (!bConfirmForAnimation) {
if (!sInstance.mPowerManager.isScreenOn()) {
bPlayaudio = false;
}
}

// throw up an indeterminate system dialog to indicate radio is
// shutting down.
beginAnimationTime = 0;
boolean mShutOffAnimation = false;

try {
if (mIBootAnim == null) {
mIBootAnim = MediatekClassFactory.createInstance(IBootAnimExt.class);
}
} catch (Exception e) {
e.printStackTrace();
}

int screenTurnOffTime = mIBootAnim.getScreenTurnOffTime();
mShutOffAnimation = mIBootAnim.isCustBootAnim();
Log.e(TAG, "mIBootAnim get screenTurnOffTime : " + screenTurnOffTime);

String cust = SystemProperties.get("ro.operator.optr");

if (cust != null) {
if (cust.equals("CUST")) {
mShutOffAnimation = true;
}
}

synchronized (mEnableAnimatingSync) {

if(!mEnableAnimating) {
// sInstance.mPowerManager.setBacklightBrightness(PowerManager.BRIGHTNESS_DIM);
} else {
if (mShutOffAnimation) {
Log.e(TAG, "mIBootAnim.isCustBootAnim() is true");
bootanimCust();
} else {
pd = new ProgressDialog(context);
pd.setTitle(context.getText(com.android.internal.R.string.power_off));
pd.setMessage(context.getText(com.android.internal.R.string.shutdown_progress));
pd.setIndeterminate(true);
pd.setCancelable(false);
pd.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
/* To fix video+UI+blur flick issue */
pd.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
pd.show();
}
sInstance.mHandler.postDelayed(mDelayDim, screenTurnOffTime );
}
}

// make sure we never fall asleep again
sInstance.mCpuWakeLock = null;
try {
sInstance.mCpuWakeLock = sInstance.mPowerManager.newWakeLock(
。。。 。。。
}
*********************************************************************************
这段代码有句话会影响关机动画播放不完 “sInstance.mHandler.postDelayed(mDelayDim, screenTurnOffTime ); ”
解决办法
    （1）“可以把这个screenTurnOffTime时间乘以2，这个时间看log是5000毫秒，就是5秒，乘以2就是10秒，大概就能播放完全关机动画了。”
    （2）把这句话注释掉，但是有可能会引起问题，导致恢复出厂设置的时候没有进行恢复出厂的操作。目前正在追踪此问题；
然后重点看 sInstance.start();这个方法，就走到了run（）方法里满了；
*********************************************************************************

(6) 来看看ShutDownThread.java这个类的run（）方法；
public void run() {
checkShutdownFlow();
while (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
stMgr.saveStates(mContext);
stMgr.enterShutdown(mContext);
running();
}
if (mShutdownFlow != IPO_SHUTDOWN_FLOW) {
stMgr.enterShutdown(mContext);
running();
}
}
重点看running（）这个方法： 下面这个方法比较长，来分析一下：
public void running() {
if(sPreShutdownApi != null){
try {
sPreShutdownApi.onPowerOff();
} catch (RemoteException e) {
Log.e(TAG, "onPowerOff exception" + e.getMessage());
}
}else{
Log.w(TAG, "sPreShutdownApi is null");
}

command = SystemProperties.get("sys.ipo.pwrdncap");

BroadcastReceiver br = new BroadcastReceiver() {
@Override public void onReceive(Context context, Intent intent) {
// We don't allow apps to cancel this, so ignore the result.
actionDone();
}
};

/*
* Write a system property in case the system_server reboots before we
* get to the actual hardware restart. If that happens, we'll retry at
* the beginning of the SystemServer startup.
*/
{
String reason = (mReboot ? "1" : "0") + (mRebootReason != null ? mRebootReason : "");
SystemProperties.set(SHUTDOWN_ACTION_PROPERTY, reason);
}

/*
* If we are rebooting into safe mode, write a system property
* indicating so.
*/
if (mRebootSafeMode) {
SystemProperties.set(REBOOT_SAFEMODE_PROPERTY, "1");
}

Log.i(TAG, "Sending shutdown broadcast...");

// First send the high-level shut down broadcast.
mActionDone = false;
/// M: 2012-05-20 ALPS00286063 @{
mContext.sendBroadcast(new Intent("android.intent.action.ACTION_PRE_SHUTDOWN"));
/// @} 2012-05-20
mContext.sendOrderedBroadcastAsUser((new Intent()).setAction(Intent.ACTION_SHUTDOWN).putExtra("_mode", mShutdownFlow),
UserHandle.ALL, null, br, mHandler, 0, null, null);

final long endTime = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;
synchronized (mActionDoneSync) {
while (!mActionDone) {
long delay = endTime - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown broadcast ACTION_SHUTDOWN timed out");
if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
Log.d(TAG, "change shutdown flow from ipo to normal: ACTION_SHUTDOWN timeout");
mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
}
break;
}
try {
mActionDoneSync.wait(delay);
} catch (InterruptedException e) {
}
}
}

// Also send ACTION_SHUTDOWN_IPO in IPO shut down flow
if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
mActionDone = false;
mContext.sendOrderedBroadcast(new Intent("android.intent.action.ACTION_SHUTDOWN_IPO"), null,
br, mHandler, 0, null, null);
final long endTimeIPO = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;
synchronized (mActionDoneSync) {
while (!mActionDone) {
long delay = endTimeIPO - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown broadcast ACTION_SHUTDOWN_IPO timed out");
if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
Log.d(TAG, "change shutdown flow from ipo to normal: ACTION_SHUTDOWN_IPO timeout");
mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
}
break;
}
try {
mActionDoneSync.wait(delay);
} catch (InterruptedException e) {
}
}
}
}

if (mShutdownFlow != IPO_SHUTDOWN_FLOW) {
// power off auto test, don't modify
Log.i(TAG, "Shutting down activity manager...");

final IActivityManager am =
ActivityManagerNative.asInterface(ServiceManager.checkService("activity"));
if (am != null) {
try {
am.shutdown(MAX_BROADCAST_TIME);
} catch (RemoteException e) {
}
}
}

// power off auto test, don't modify
// Shutdown radios.
Log.i(TAG, "Shutting down radios...");
shutdownRadios(MAX_RADIO_WAIT_TIME);

// power off auto test, don't modify
Log.i(TAG, "Shutting down MountService...");
if ( (mShutdownFlow == IPO_SHUTDOWN_FLOW) && (command.equals("1")||command.equals("3")) ) {
Log.i(TAG, "bypass MountService!");
} else {
// Shutdown MountService to ensure media is in a safe state
IMountShutdownObserver observer = new IMountShutdownObserver.Stub() {
public void onShutDownComplete(int statusCode) throws RemoteException {
Log.w(TAG, "Result code " + statusCode + " from MountService.shutdown");
if (statusCode < 0) {
mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
}
actionDone();
}
};



// Set initial variables and time out time.
mActionDone = false;
final long endShutTime = SystemClock.elapsedRealtime() + MAX_SHUTDOWN_WAIT_TIME;
synchronized (mActionDoneSync) {
try {
final IMountService mount = IMountService.Stub.asInterface(
ServiceManager.checkService("mount"));
if (mount != null) {
mount.shutdown(observer);
} else {
Log.w(TAG, "MountService unavailable for shutdown");
}
} catch (Exception e) {
Log.e(TAG, "Exception during MountService shutdown", e);
}
while (!mActionDone) {
long delay = endShutTime - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown wait timed out");
if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
Log.d(TAG, "change shutdown flow from ipo to normal: MountService");
mShutdownFlow = NORMAL_SHUTDOWN_FLOW;
}
break;
}
try {
mActionDoneSync.wait(delay);
} catch (InterruptedException e) {
}
}
}
}

// power off auto test, don't modify
//mountSerivce ���
Log.i(TAG, "MountService shut done...");
// [MTK] fix shutdown animation timing issue
//==================================================================
try {
SystemProperties.set("service.shutanim.running","1");
Log.i(TAG, "set service.shutanim.running to 1");

} catch (Exception ex) {
Log.e(TAG, "Failed to set 'service.shutanim.running' = 1).");
}
//==================================================================

if (mShutdownFlow == IPO_SHUTDOWN_FLOW) {
if (SHUTDOWN_VIBRATE_MS > 0) {
// vibrate before shutting down
Vibrator vibrator = new SystemVibrator();
try {
vibrator.vibrate(SHUTDOWN_VIBRATE_MS);
} catch (Exception e) {
// Failure to vibrate shouldn't interrupt shutdown. Just log it.
Log.w(TAG, "Failed to vibrate during shutdown.", e);
}

// vibrator is asynchronous so we need to wait to avoid shutting down too soon.
try {
Thread.sleep(SHUTDOWN_VIBRATE_MS);
} catch (InterruptedException unused) {
}
}

// Shutdown power
// power off auto test, don't modify
Log.i(TAG, "Performing ipo low-level shutdown...");

delayForPlayAnimation();

if (sInstance.mScreenWakeLock != null && sInstance.mScreenWakeLock.isHeld()) {
sInstance.mScreenWakeLock.release();
sInstance.mScreenWakeLock = null;
}

sInstance.mHandler.removeCallbacks(mDelayDim);
stMgr.shutdown(mContext);
stMgr.finishShutdown(mContext);

//To void previous UI flick caused by shutdown animation stopping before BKL turning off
if (pd != null) {
pd.dismiss();
pd = null;
} else if (beginAnimationTime > 0) {
try {
SystemProperties.set("service.bootanim.exit","1");
Log.i(TAG, "set 'service.bootanim.exit' = 1).");
} catch (Exception ex) {
Log.e(TAG, "Failed to set 'service.bootanim.exit' = 1).");
}
//SystemProperties.set("ctl.stop","bootanim");
}

synchronized (sIsStartedGuard) {
sIsStarted = false;
}

sInstance.mPowerManager.setBacklightBrightnessOff(false);
sInstance.mCpuWakeLock.acquire(2000);

synchronized (mShutdownThreadSync) {
try {
mShutdownThreadSync.wait();
} catch (InterruptedException e) {
}
}
} else {
rebootOrShutdown(mReboot, mRebootReason);
}
}
这个方法做了一些列的操作，会关闭一些操作，如：
a.  shutdownRadios(MAX_RADIO_WAIT_TIME);
b. mount.shutdown(observer);
c. stMgr.shutdown(mContext);
重点看  rebootOrShutdown(mReboot, mRebootReason);这个方法；准备重启的方法；
(7) 来看看rebootOrShutdown（）这个方法：
public static void rebootOrShutdown(boolean reboot, String reason) {
if (reboot) {
Log.i(TAG, "Rebooting, reason: " + reason);
if ( (reason != null) && reason.equals("recovery") ) {
delayForPlayAnimation();
}
try {
PowerManagerService.lowLevelReboot(reason);
} catch (Exception e) {
Log.e(TAG, "Reboot failed, will attempt shutdown instead", e);
}
} else if (SHUTDOWN_VIBRATE_MS > 0) {
// vibrate before shutting down
Vibrator vibrator = new SystemVibrator();
try {
vibrator.vibrate(SHUTDOWN_VIBRATE_MS);
} catch (Exception e) {
// Failure to vibrate shouldn't interrupt shutdown. Just log it.
Log.w(TAG, "Failed to vibrate during shutdown.", e);
}

// vibrator is asynchronous so we need to wait to avoid shutting down too soon.
try {
Thread.sleep(SHUTDOWN_VIBRATE_MS);
} catch (InterruptedException unused) {
}
}

delayForPlayAnimation();
// Shutdown power
// power off auto test, don't modify
Log.i(TAG, "Performing low-level shutdown...");
//PowerManagerService.lowLevelShutdown();
//add your func: HDMI off
//add for MFR
try {
if (ImHDMI == null)
ImHDMI=MediatekClassFactory.createInstance(IHDMINative.class);
} catch (Exception e) {
e.printStackTrace();
}
ImHDMI.hdmiPowerEnable(false);
try {
if (mTvOut == null)
mTvOut =MediatekClassFactory.createInstance(ITVOUTNative.class);
} catch (Exception e) {
e.printStackTrace();
}

mTvOut.tvoutPowerEnable(false);
//add your func: HDMI off
//unmout data/cache partitions while performing shutdown

SystemProperties.set("ctl.start", "shutdown");

/* sleep for a long time, prevent start another service */
try {
Thread.currentThread().sleep(Integer.MAX_VALUE);
} catch ( Exception e) {
Log.e(TAG, "Shutdown rebootOrShutdown Thread.currentThread().sleep exception!");
}
}
关机震动也在这个方法里面；这个方法重点看PowerManagerService.lowLevelReboot(reason);  
Log.i(TAG, "Rebooting, reason: " + reason);这句log也很重要，可以有助于我们分析代码；
(8)下面来看看PowerManagerServices.java这个类的lowLevelReboot（）这个方法：
public static void lowLevelReboot(String reason) throws IOException {
SystemProperties.set("ctl.start", "pre-recovery");
}
到此,设备执行完回复出厂设置的关机阶段,然后重启进入recovery模式
设备启动时,此处ctl.start设备启动参数,将设备启动到recovery模式中.

在init.rc启动的服务中,识别到启动的是recovery模式,启动recovery模式,在recovery中,进入recovery流程
* FACTORY RESET
* 1. user selects "factory reset"
* 2. main system writes "--wipe_data" to /cache/recovery/command
* 3. main system reboots into recovery
* 4. get_args() writes BCB with "boot-recovery" and "--wipe_data"
* -- after this, rebooting will restart the erase --
* 5. erase_volume() reformats /data
* 6. erase_volume() reformats /cache
* 7. finish_recovery() erases BCB
* -- after this, rebooting will restart the main system --
* 8. main() calls reboot() to boot main system
http://blog.csdn.net/yicao821/article/details/7109393
下面是recovery流程分析,主函数在文件中:
bootable/recovery/recovery.c 
int main(int argc, char **argv)
...
ui_init(); //初始化ui
get_args(&argc, &argv);
...
void ui_init(void)
{
gr_init();
ev_init();
...
pthread_create(&t, NULL, progress_thread, NULL);
pthread_create(&t, NULL, input_thread, NULL);
}
函数get_args会读取/cache/recovery/command文件,并根据命令字段进行相应的操作
因为进行恢复出厂设置的时候在/cache/recovery/command的内容为 --wipe-data , 所以会擦出data和cache分区:
erase_root("DATA"); erase_root("CACHE");
擦出后,系统重启,然后进入正常的开机流程.