宣告
- 前階段在專案中涉及到了Android系統定制任務，Android系統定制前提要知道Android系統是如何啟動的，
- 本文參考了一些書籍的若干章節，比如《Android進階解密-第2章-Android系統啟動》、《深入理解Android虛擬機-第8/9/10章-init行程詳解/Dalvik VM的行程系統/Dalvik VM運作流程詳解》、《深入理解Android系統-第6/7/8章-init啟動行程詳解/Zygote行程詳解/System行程詳解》等，
- 本文使用的代碼是LineageOS的cm-14.1，對應Android 7.1.2，可以參考我的另一篇博客：cm-14.1 Android系統啟動程序分析（〇）-如何下載Nexus5的LineageOS14.1(cm-14.1)系統原始碼并編譯、刷機，
- 很多代碼注釋待詳細寫
0 寫在前面的
????等本章結束，Android系統的啟動基本就結束了，因為對于用戶來說可以看到顯示屏上的Launcher界面就代表系統已經啟動完成了，Launcher在啟動程序中會請求 PackageManagerService 回傳系統中已經安裝的應用程式的資訊，并將這些資訊封裝成一個快捷圖示串列顯示在系統螢屏上，這樣用戶可以通過點擊這些快捷圖示來啟動相應的應用程式，
????Launcher 就是 Android 系統的桌面，它的作用主要有以下兩點：
- 用于啟動應用程式，
- 用于顯示和管理應用程式的快捷圖示或者其他桌面組件，
0 Launcher啟動程序
????SystemServer 行程在啟動的程序中會啟動PackageManagerService, PackageManagerService 啟動后會將系統中的預置的應用程式安裝（其中就包含Launcher應用），然后系統服務 AMS 會將 Launcher 啟動起來，
????啟動Launcher的入口為AMS的systemReady方法，它在SystemServer的startOtherServices 方告中被呼叫，其在原始碼目錄：~/LineageOS/frameworks/base/services/java/com/android/server/SystemServer.java
// We now tell the activity manager it is okay to run third party
// code. It will call back into us once it has gotten to the state
// where third party code can really run (but before it has actually
// started launching the initial applications), for us to complete our
// initialization.
mActivityManagerService.systemReady(new Runnable() {
@Override
public void run() {
Slog.i(TAG, "Making services ready");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "PhaseActivityManagerReady");
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartObservingNativeCrashes");
try {
mActivityManagerService.startObservingNativeCrashes();
} catch (Throwable e) {
reportWtf("observing native crashes", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
if (!mOnlyCore) {
Slog.i(TAG, "WebViewFactory preparation");
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "WebViewFactoryPreparation");
mWebViewUpdateService.prepareWebViewInSystemServer();
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
}
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartSystemUI");
try {
startSystemUi(context);
} catch (Throwable e) {
reportWtf("starting System UI", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "MakeNetworkScoreReady");
try {
if (networkScoreF != null) networkScoreF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Score Service ready", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "MakeNetworkManagementServiceReady");
try {
if (networkManagementF != null) networkManagementF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Managment Service ready", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "MakeNetworkStatsServiceReady");
try {
if (networkStatsF != null) networkStatsF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Stats Service ready", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "MakeNetworkPolicyServiceReady");
try {
if (networkPolicyF != null) networkPolicyF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Policy Service ready", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "MakeConnectivityServiceReady");
try {
if (connectivityF != null) connectivityF.systemReady();
} catch (Throwable e) {
reportWtf("making Connectivity Service ready", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Watchdog.getInstance().start();
// It is now okay to let the various system services start their
// third party code...
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "PhaseThirdPartyAppsCanStart");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_THIRD_PARTY_APPS_CAN_START);
try {
if (locationF != null) locationF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying Location Service running", e);
}
try {
if (countryDetectorF != null) countryDetectorF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying CountryDetectorService running", e);
}
try {
if (networkTimeUpdaterF != null) networkTimeUpdaterF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying NetworkTimeService running", e);
}
try {
if (commonTimeMgmtServiceF != null) {
commonTimeMgmtServiceF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying CommonTimeManagementService running", e);
}
try {
if (atlasF != null) atlasF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying AssetAtlasService running", e);
}
try {
// TODO(BT) Pass parameter to input manager
if (inputManagerF != null) inputManagerF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying InputManagerService running", e);
}
try {
if (telephonyRegistryF != null) telephonyRegistryF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying TelephonyRegistry running", e);
}
try {
if (mediaRouterF != null) mediaRouterF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying MediaRouterService running", e);
}
try {
if (mmsServiceF != null) mmsServiceF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying MmsService running", e);
}
try {
if (networkScoreF != null) networkScoreF.systemRunning();
} catch (Throwable e) {
reportWtf("Notifying NetworkScoreService running", e);
}
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
}
});
}
下面來查看 AMS systernReady 方法做了什么，其在原始碼目錄：~/LineageOS/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
public void systemReady(final Runnable goingCallback) {
synchronized(this) {
if (mSystemReady) {
// If we're done calling all the receivers, run the next "boot phase" passed in
// by the SystemServer
if (goingCallback != null) {
goingCallback.run();
}
return;
}
mLocalDeviceIdleController
= LocalServices.getService(DeviceIdleController.LocalService.class);
// Make sure we have the current profile info, since it is needed for security checks.
mUserController.onSystemReady();
mRecentTasks.onSystemReadyLocked();
mAppOpsService.systemReady();
mSystemReady = true;
}
ArrayList<ProcessRecord> procsToKill = null;
synchronized(mPidsSelfLocked) {
for (int i=mPidsSelfLocked.size()-1; i>=0; i--) {
ProcessRecord proc = mPidsSelfLocked.valueAt(i);
if (!isAllowedWhileBooting(proc.info)){
if (procsToKill == null) {
procsToKill = new ArrayList<ProcessRecord>();
}
procsToKill.add(proc);
}
}
}
synchronized(this) {
if (procsToKill != null) {
for (int i=procsToKill.size()-1; i>=0; i--) {
ProcessRecord proc = procsToKill.get(i);
Slog.i(TAG, "Removing system update proc: " + proc);
removeProcessLocked(proc, true, false, "system update done");
}
}
// Now that we have cleaned up any update processes, we
// are ready to start launching real processes and know that
// we won't trample on them any more.
mProcessesReady = true;
}
Slog.i(TAG, "System now ready");
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_AMS_READY,
SystemClock.uptimeMillis());
synchronized(this) {
// Make sure we have no pre-ready processes sitting around.
if (mFactoryTest == FactoryTest.FACTORY_TEST_LOW_LEVEL) {
ResolveInfo ri = mContext.getPackageManager()
.resolveActivity(new Intent(Intent.ACTION_FACTORY_TEST),
STOCK_PM_FLAGS);
CharSequence errorMsg = null;
if (ri != null) {
ActivityInfo ai = ri.activityInfo;
ApplicationInfo app = ai.applicationInfo;
if ((app.flags&ApplicationInfo.FLAG_SYSTEM) != 0) {
mTopAction = Intent.ACTION_FACTORY_TEST;
mTopData = null;
mTopComponent = new ComponentName(app.packageName,
ai.name);
} else {
errorMsg = mContext.getResources().getText(
com.android.internal.R.string.factorytest_not_system);
}
} else {
errorMsg = mContext.getResources().getText(
com.android.internal.R.string.factorytest_no_action);
}
if (errorMsg != null) {
mTopAction = null;
mTopData = null;
mTopComponent = null;
Message msg = Message.obtain();
msg.what = SHOW_FACTORY_ERROR_UI_MSG;
msg.getData().putCharSequence("msg", errorMsg);
mUiHandler.sendMessage(msg);
}
}
}
retrieveSettings();
final int currentUserId;
synchronized (this) {
currentUserId = mUserController.getCurrentUserIdLocked();
readGrantedUriPermissionsLocked();
}
if (goingCallback != null) goingCallback.run();
mBatteryStatsService.noteEvent(BatteryStats.HistoryItem.EVENT_USER_RUNNING_START,
Integer.toString(currentUserId), currentUserId);
mBatteryStatsService.noteEvent(BatteryStats.HistoryItem.EVENT_USER_FOREGROUND_START,
Integer.toString(currentUserId), currentUserId);
mSystemServiceManager.startUser(currentUserId);
synchronized (this) {
// Only start up encryption-aware persistent apps; once user is
// unlocked we'll come back around and start unaware apps
startPersistentApps(PackageManager.MATCH_DIRECT_BOOT_AWARE);
// Start up initial activity.
mBooting = true;
// Enable home activity for system user, so that the system can always boot
if (UserManager.isSplitSystemUser()) {
ComponentName cName = new ComponentName(mContext, SystemUserHomeActivity.class);
try {
AppGlobals.getPackageManager().setComponentEnabledSetting(cName,
PackageManager.COMPONENT_ENABLED_STATE_ENABLED, 0,
UserHandle.USER_SYSTEM);
} catch (RemoteException e) {
throw e.rethrowAsRuntimeException();
}
}
startHomeActivityLocked(currentUserId, "systemReady");
try {
if (AppGlobals.getPackageManager().hasSystemUidErrors()) {
Slog.e(TAG, "UIDs on the system are inconsistent, you need to wipe your"
+ " data partition or your device will be unstable.");
mUiHandler.obtainMessage(SHOW_UID_ERROR_UI_MSG).sendToTarget();
}
} catch (RemoteException e) {
}
if (!Build.isBuildConsistent()) {
Slog.e(TAG, "Build fingerprint is not consistent, warning user");
mUiHandler.obtainMessage(SHOW_FINGERPRINT_ERROR_UI_MSG).sendToTarget();
}
long ident = Binder.clearCallingIdentity();
try {
Intent intent = new Intent(Intent.ACTION_USER_STARTED);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
| Intent.FLAG_RECEIVER_FOREGROUND);
intent.putExtra(Intent.EXTRA_USER_HANDLE, currentUserId);
broadcastIntentLocked(null, null, intent,
null, null, 0, null, null, null, AppOpsManager.OP_NONE,
null, false, false, MY_PID, Process.SYSTEM_UID,
currentUserId);
intent = new Intent(Intent.ACTION_USER_STARTING);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
intent.putExtra(Intent.EXTRA_USER_HANDLE, currentUserId);
broadcastIntentLocked(null, null, intent,
null, new IIntentReceiver.Stub() {
@Override
public void performReceive(Intent intent, int resultCode, String data,
Bundle extras, boolean ordered, boolean sticky, int sendingUser)
throws RemoteException {
}
}, 0, null, null,
new String[] {INTERACT_ACROSS_USERS}, AppOpsManager.OP_NONE,
null, true, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
} catch (Throwable t) {
Slog.wtf(TAG, "Failed sending first user broadcasts", t);
} finally {
Binder.restoreCallingIdentity(ident);
}
//呼叫了ActivityStackSupervisor的resumeFocusedStackTopActivityLocked方法；
mStackSupervisor.resumeFocusedStackTopActivityLocked();
mUserController.sendUserSwitchBroadcastsLocked(-1, currentUserId);
}
}
進入到原始碼目錄：~/LineageOS/frameworks/base/services/core/java/com/android/server/am/ActivityStackSupervisor.java
boolean resumeFocusedStackTopActivityLocked() {
return resumeFocusedStackTopActivityLocked(null, null, null);
}
boolean resumeFocusedStackTopActivityLocked(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
if (targetStack != null && isFocusedStack(targetStack)) {
//呼叫ActivityStack的resumeTopActivityUncheckedLocked方法，ActivityStack物件用來描述Activity堆疊
return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
}
final ActivityRecord r = mFocusedStack.topRunningActivityLocked();
if (r == null || r.state != RESUMED) {
mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
}
return false;
}
ActivityStack的resumeTopActivityUncheckedLocked方法在原始碼目錄：~/LineageOS/frameworks/base/services/core/java/com/android/server/am/ActivityStack.java
/**
* Ensure that the top activity in the stack is resumed.
*
* @param prev The previously resumed activity, for when in the process
* of pausing; can be null to call from elsewhere.
* @param options Activity options.
*
* @return Returns true if something is being resumed, or false if
* nothing happened.
*
* NOTE: It is not safe to call this method directly as it can cause an activity in a
* non-focused stack to be resumed.
* Use {@link ActivityStackSupervisor#resumeFocusedStackTopActivityLocked} to resume the
* right activity for the current system state.
*/
boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
if (mStackSupervisor.inResumeTopActivity) {
// Don't even start recursing.
return false;
}
boolean result = false;
try {
// Protect against recursion.
mStackSupervisor.inResumeTopActivity = true;
if (mService.mLockScreenShown == ActivityManagerService.LOCK_SCREEN_LEAVING) {
mService.mLockScreenShown = ActivityManagerService.LOCK_SCREEN_HIDDEN;
mService.updateSleepIfNeededLocked();
}
//呼叫resumeTopActivityInnerLocked方法
result = resumeTopActivityInnerLocked(prev, options);
} finally {
mStackSupervisor.inResumeTopActivity = false;
}
return result;
}
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
if (DEBUG_LOCKSCREEN) mService.logLockScreen("");
if (!mService.mBooting && !mService.mBooted) {
// Not ready yet!
return false;
}
ActivityRecord parent = mActivityContainer.mParentActivity;
if ((parent != null && parent.state != ActivityState.RESUMED) ||
!mActivityContainer.isAttachedLocked()) {
// Do not resume this stack if its parent is not resumed.
// TODO: If in a loop, make sure that parent stack resumeTopActivity is called 1st.
return false;
}
mStackSupervisor.cancelInitializingActivities();
// Find the first activity that is not finishing.
final ActivityRecord next = topRunningActivityLocked();
// Remember how we'll process this pause/resume situation, and ensure
// that the state is reset however we wind up proceeding.
final boolean userLeaving = mStackSupervisor.mUserLeaving;
mStackSupervisor.mUserLeaving = false;
final TaskRecord prevTask = prev != null ? prev.task : null;
if (next == null) {
// There are no more activities!
final String reason = "noMoreActivities";
final int returnTaskType = prevTask == null || !prevTask.isOverHomeStack()
? HOME_ACTIVITY_TYPE : prevTask.getTaskToReturnTo();
if (!mFullscreen && adjustFocusToNextFocusableStackLocked(returnTaskType, reason)) {
// Try to move focus to the next visible stack with a running activity if this
// stack is not covering the entire screen.
return mStackSupervisor.resumeFocusedStackTopActivityLocked(
mStackSupervisor.getFocusedStack(), prev, null);
}
// Let's just start up the Launcher...
ActivityOptions.abort(options);
if (DEBUG_STATES) Slog.d(TAG_STATES,
"resumeTopActivityLocked: No more activities go home");
if (DEBUG_STACK) mStackSupervisor.validateTopActivitiesLocked();
// Only resume home if on home display
// 呼叫ActivityStackSupervisor 的resumeHomeStackTask方法
return isOnHomeDisplay() &&
mStackSupervisor.resumeHomeStackTask(returnTaskType, prev, reason);
}
next.delayedResume = false;
......
}
呼叫ActivityStackSupervisor 的resumeHomeStackTask方法在原始碼目錄：~/LineageOS/frameworks/base/services/core/java/com/android/server/am/ActivityStackSupervisor.java
boolean resumeHomeStackTask(int homeStackTaskType, ActivityRecord prev, String reason) {
if (!mService.mBooting && !mService.mBooted) {
// Not ready yet!
return false;
}
if (homeStackTaskType == RECENTS_ACTIVITY_TYPE) {
mWindowManager.showRecentApps(false /* fromHome */);
return false;
}
if (prev != null) {
prev.task.setTaskToReturnTo(APPLICATION_ACTIVITY_TYPE);
}
mHomeStack.moveHomeStackTaskToTop(homeStackTaskType);
ActivityRecord r = getHomeActivity();
final String myReason = reason + " resumeHomeStackTask";
// Only resume home activity if isn't finishing.
if (r != null && !r.finishing) {
mService.setFocusedActivityLocked(r, myReason);
return resumeFocusedStackTopActivityLocked(mHomeStack, prev, null);
}
// 呼叫AMS的startHomeActivityLocked方法
return mService.startHomeActivityLocked(mCurrentUser, myReason);
}
AMS的startHomeActivityLocked方法,在原始碼目錄：~/LineageOS/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
boolean startHomeActivityLocked(int userId, String reason) {
// 判斷工廠模式和mTopAction 的值，符合要求就繼續執行下去，mFactoryTest 代表系統的運行模式，系統的運行模式分為 種，分別是非工廠模式、
// 低級工廠模式和高級工廠模式， mTopAction 則用來描述第 個被啟動 Activity組件的 Action ，它的默認值為
// Intent.ACTION_MAIN 因此注釋 處的代碼的意思就是mFactoryTest FactoryTest.FACTORY_TEST LOW_LEVEL （低級工廠模式）
// 并且mTopAction 等于 null 時，直接回傳 false
if (mFactoryTest == FactoryTest.FACTORY_TEST_LOW_LEVEL
&& mTopAction == null) {
// We are running in factory test mode, but unable to find
// the factory test app, so just sit around displaying the
// error message and don't try to start anything.
return false;
}
// 創建Launcher啟動所需的Intent
Intent intent = getHomeIntent();
ActivityInfo aInfo = resolveActivityInfo(intent, STOCK_PM_FLAGS, userId);
if (aInfo != null) {
intent.setComponent(new ComponentName(aInfo.applicationInfo.packageName, aInfo.name));
// Don't do this if the home app is currently being
// instrumented.
aInfo = new ActivityInfo(aInfo);
aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId);
ProcessRecord app = getProcessRecordLocked(aInfo.processName,
aInfo.applicationInfo.uid, true);
// 假設系統的運行模式不是低級 廠模式，判斷符合 Action Intent.ACTION_MAIN 、Category為 Intent.CATEGORY_HOME 的應用程式是否已 啟動，如果沒啟動則呼叫mActivityStarter.startHomeActivityLocked(intent, aInfo, reason);啟動該應用程式，
// 這個被啟動的應用程式就是Launcher，Launcher的AndroidManifest 檔案中的 intent-filter匹配了Action為Intent.ACTION_MAIN，Category為Intent.CATEGORY_HOME
if (app == null || app.instrumentationClass == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
mActivityStarter.startHomeActivityLocked(intent, aInfo, reason);
}
} else {
Slog.wtf(TAG, "No home screen found for " + intent, new Throwable());
}
return true;
}
// mTopAction的值為 Intent.ACTION_MAIN ，并且如果系統運行模式不是低級工廠模式，則將 intent的Category 設定為 Intent.CATEGORY_HOME 后回傳 Intent ，再回到 AMS的startHomeActivityLocked方法
Intent getHomeIntent() {
Intent intent = new Intent(mTopAction, mTopData != null ? Uri.parse(mTopData) : null);
intent.setComponent(mTopComponent);
intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) {
intent.addCategory(Intent.CATEGORY_HOME);
}
return intent;
}
ActivityStarter的startHomeActivityLocked方法在原始碼目錄：~/LineageOS/frameworks/base/services/core/java/com/android/server/am/ActivityStarter.java
void startHomeActivityLocked(Intent intent, ActivityInfo aInfo, String reason) {
// 將Launcher放入HomeStack中，HomeStack是在ActivityStackSupervisor中定義的用于存盤Launcher的變數，再呼叫startActivityLocked方法來啟動 Launcher，然后啟動Launcher的Activity了...
mSupervisor.moveHomeStackTaskToTop(HOME_ACTIVITY_TYPE, reason);
startActivityLocked(null /*caller*/, intent, null /*ephemeralIntent*/,
null /*resolvedType*/, aInfo, null /*rInfo*/, null /*voiceSession*/,
null /*voiceInteractor*/, null /*resultTo*/, null /*resultWho*/,
0 /*requestCode*/, 0 /*callingPid*/, 0 /*callingUid*/, null /*callingPackage*/,
0 /*realCallingPid*/, 0 /*realCallingUid*/, 0 /*startFlags*/, null /*options*/,
false /*ignoreTargetSecurity*/, false /*componentSpecified*/, null /*outActivity*/,
null /*container*/, null /*inTask*/);
if (mSupervisor.inResumeTopActivity) {
// If we are in resume section already, home activity will be initialized, but not
// resumed (to avoid recursive resume) and will stay that way until something pokes it
// again. We need to schedule another resume.
mSupervisor.scheduleResumeTopActivities();
}
}
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