概述
PackageManagerService是android系統(tǒng)核心服務(wù)之一蒙袍，在Android中非常重要骚烧，主要負責的功能如下：
解析AndroidManifest.xml 主要包括AndoridManifest中節(jié)點的信息。
掃描本地文件夸政，主要針對apk元旬，主要是系統(tǒng)應(yīng)用，本地安裝應(yīng)用等守问。
管理本地apk匀归，主要包括安裝和刪除等。
啟動過程
PKMS服務(wù)由SystemServer進行啟動耗帕，在SystemServer中startBootstrapServices()啟動PKMS服務(wù)穆端，在調(diào)用startOtherServices進行dex優(yōu)化，磁盤管理等功能仿便，并讓PKMS進入systemReady狀態(tài)体啰。
SystemServer.java#startBootstrapServices()
startBootstrapServices首先啟動Installer服務(wù)，也就是安裝器嗽仪，隨后判斷當前的設(shè)備是否處于加密狀態(tài)荒勇，如果是則只解析核心應(yīng)用，接著調(diào)用PKMS的靜態(tài)方法main來創(chuàng)建pkms對象
private void startBootstrapServices() {
...
// Wait for installd to finish starting up so that it has a chance to
// create critical directories such as /data/user with the appropriate
// permissions. We need this to complete before we initialize other services.
//(1)啟動Installer
//阻塞等待installd完成啟動钦幔，以便有機會創(chuàng)建具有適當權(quán)限的關(guān)鍵目錄，如/data/user常柄。
//我們需要在初始化其他服務(wù)之前完成此任務(wù)鲤氢。
Installer installer = mSystemServiceManager.startService(Installer.class);
mActivityManagerService.setInstaller(installer);
...
// Only run "core" apps if we're encrypting the device.
//(2)獲取設(shè)別是否加密(手機設(shè)置密碼)，如果設(shè)備加密了西潘，則只解析"core"應(yīng)用卷玉，mOnlyCore = true，后面會頻繁使用該變量進行條件判斷
String cryptState = VoldProperties.decrypt().orElse("");
if (ENCRYPTING_STATE.equals(cryptState)) {
Slog.w(TAG, "Detected encryption in progress - only parsing core apps");
mOnlyCore = true;
} else if (ENCRYPTED_STATE.equals(cryptState)) {
Slog.w(TAG, "Device encrypted - only parsing core apps");
mOnlyCore = true;
}
//(3)調(diào)用main方法初始化PackageManagerService喷市。
mPackageManagerService = PackageManagerService.main(mSystemContext, installer,
mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore);
//PKMS是否是第一次啟動
mFirstBoot = mPackageManagerService.isFirstBoot();
//(4)如果設(shè)備沒有加密相种，操作它。管理A/B OTA dexopting品姓。
if (!mOnlyCore) {
boolean disableOtaDexopt = SystemProperties.getBoolean("config.disable_otadexopt",
false);
OtaDexoptService.main(mSystemContext, mPackageManagerService);
}
...
}
startOtherServices
- 執(zhí)行updatePackagesIfNeeded寝并，完成dex優(yōu)化
- 執(zhí)行performFstrimIfNeeded 完成磁盤維護
- 調(diào)用systemReady 準備就緒
private void startOtherServices() {
...
if (!mOnlyCore) {
...
//(5)如果設(shè)備沒有加密箫措，執(zhí)行performDexOptUpgrade，完成dex優(yōu)化衬潦；
mPackageManagerService.updatePackagesIfNeeded();
}
...
//(6) 最終執(zhí)行performFstrim斤蔓，完成磁盤維護
mPackageManagerService.performFstrimIfNeeded();
...
//(7)PKMS準備就緒
mPackageManagerService.systemReady();
...
}
PackageManagerService.java#main()
main函數(shù)主要工作：
- 檢查Package編譯相關(guān)系統(tǒng)屬性
- 調(diào)用PackageManagerService構(gòu)造方法
- 啟動部分應(yīng)用服務(wù)于多用戶場景
- 往ServiceManager中注冊
package和package_native。
public static PackageManagerService main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
// (1)檢查Package編譯相關(guān)系統(tǒng)屬性
PackageManagerServiceCompilerMapping.checkProperties();
//(2)調(diào)用PackageManagerService構(gòu)造方法
PackageManagerService m = new PackageManagerService(context, installer,
factoryTest, onlyCore);
//(3)啟用部分應(yīng)用服務(wù)于多用戶場景
m.enableSystemUserPackages();
//(4)往ServiceManager中注冊”package”和”package_native”镀岛。
ServiceManager.addService("package", m);
final PackageManagerNative pmn = m.new PackageManagerNative();
ServiceManager.addService("package_native", pmn);
return m;
}
PKMS初始化時的核心部分為PackageManagerService()構(gòu)造函數(shù)的內(nèi)容弦牡，我們接下來就來分析該流程。
PKMS構(gòu)造函數(shù)分析
主要有兩個重要的鎖(mInstallLock,mPackages)和五個階段構(gòu)成漂羊。
mPackages:用來解析內(nèi)存中所有apk的package信息以及相關(guān)狀態(tài)驾锰。
五個階段：
階段1：BOOT_PROGRESS_PMS_START
階段2：BOOT_PROGRESS_PMS_SYSTEM_SCAN_START
階段3：BOOT_PROGRESS_PMS_DATA_SCAN_START
階段4：BOOT_PROGRESS_PMS_SCAN_END
階段5：BOOT_PROGRESS_PMS_READY
PKMS服務(wù)也是通過binder進行通信，IPackageManager.aidl由工具轉(zhuǎn)換后自動生成binder的服務(wù)端IPackageManager.Stub和客戶端IPackageManager.Stub.Proxy走越。Binder服務(wù)端：PackageManagerService繼承于IPackageManager.Stub
Binder客戶端：ApplicationPackageManager的成員變量mPM繼承于IPackageManager.Stub.Proxy;本身APM繼承于PackageManager對象椭豫。
PackageManagerService.java
IPacakgeManager.Stub 是IPackageManager.aidl自動生成的，正好也說明PKMS是service端买喧，通過Binder交互
public class PackageManagerService extends IPackageManager.Stub
implements PackageSender
PackageManagerService()構(gòu)造函數(shù)
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
...
//階段1：BOOT_PROGRESS_PMS_START
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
SystemClock.uptimeMillis());
//階段2：BOOT_PROGRESS_PMS_SYSTEM_SCAN_START
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
startTime);
...
//階段3：BOOT_PROGRESS_PMS_DATA_SCAN_START
if (!mOnlyCore) {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
SystemClock.uptimeMillis());
}
...
//階段4：BOOT_PROGRESS_PMS_SCAN_END
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
...
//階段5：BOOT_PROGRESS_PMS_READY
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
}
階段1：BOOT_PROGRESS_PMS_START
主要工作：
構(gòu)造DisplayMetrics捻悯，保存分辨率等相關(guān)信息
創(chuàng)建Installer對象 與InstallId交互
創(chuàng)建mPermissionManager對象，進行權(quán)限管理
構(gòu)造Settings類淤毛，保存安裝包信息今缚，清除路徑不存在的孤立應(yīng)用，主要涉及/data/system目錄下的packages.xml,package-backup.xml,packages.list,packages-stopped.xml,packages-stopped-backup.xml等文件低淡。
構(gòu)造PackageDexOptimizer及DexManager類姓言，處理dex優(yōu)化；
創(chuàng)建SystemConfig實例蔗蹋，獲取系統(tǒng)配置信息何荚，配置共享lib庫
創(chuàng)建PackageManager的handler線程，循環(huán)處理外部安裝相關(guān)消息猪杭。
public PackageManagerService(...) {
LockGuard.installLock(mPackages, LockGuard.INDEX_PACKAGES);
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
SystemClock.uptimeMillis());
mContext = context;
mFactoryTest = factoryTest; // 一般為false，即非工廠生產(chǎn)模式
mOnlyCore = onlyCore; //標記是否只加載核心服務(wù)
mMetrics = new DisplayMetrics(); // 分辨率配置
mInstaller = installer; //保存installer對象
// Create sub-components that provide services / data. Order here is important.
//創(chuàng)建提供服務(wù)/數(shù)據(jù)的子組件皂吮。這里的順序很重要,使用到了兩個重要的同步鎖：mInstallLock戒傻、mPackages
synchronized (mInstallLock) {
synchronized (mPackages) {
// Expose private service for system components to use.
// 公開系統(tǒng)組件使用的私有服務(wù)
// 本地服務(wù)
LocalServices.addService(
PackageManagerInternal.class, new PackageManagerInternalImpl());
// 多用戶管理服務(wù)
sUserManager = new UserManagerService(context, this,
new UserDataPreparer(mInstaller, mInstallLock, mContext, mOnlyCore), mPackages);
mComponentResolver = new ComponentResolver(sUserManager,
LocalServices.getService(PackageManagerInternal.class),
mPackages);
// 權(quán)限管理服務(wù)
mPermissionManager = PermissionManagerService.create(context,
mPackages /*externalLock*/);
mDefaultPermissionPolicy = mPermissionManager.getDefaultPermissionGrantPolicy();
//創(chuàng)建Settings對象
mSettings = new Settings(Environment.getDataDirectory(),
mPermissionManager.getPermissionSettings(), mPackages);
}
}
// 添加system, phone, log, nfc, bluetooth, shell，se口蝠，networkstack 這8種shareUserId到mSettings亚皂；
mSettings.addSharedUserLPw("android.uid.system", Process.SYSTEM_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.phone", RADIO_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.log", LOG_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.nfc", NFC_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.bluetooth", BLUETOOTH_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.shell", SHELL_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.se", SE_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.networkstack", NETWORKSTACK_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
...
// DexOpt優(yōu)化
mPackageDexOptimizer = new PackageDexOptimizer(installer, mInstallLock, context,
"*dexopt*");
mDexManager = new DexManager(mContext, this, mPackageDexOptimizer, installer, mInstallLock);
// ART虛擬機管理服務(wù)
mArtManagerService = new ArtManagerService(mContext, this, installer, mInstallLock);
mMoveCallbacks = new MoveCallbacks(FgThread.get().getLooper());
mViewCompiler = new ViewCompiler(mInstallLock, mInstaller);
// 權(quán)限變化監(jiān)聽器
mOnPermissionChangeListeners = new OnPermissionChangeListeners(
FgThread.get().getLooper());
mProtectedPackages = new ProtectedPackages(mContext);
mApexManager = new ApexManager(context);
// 獲取默認分辨率
getDefaultDisplayMetrics(context, mMetrics);
//拿到SystemConfig()的對象俱箱，其中會調(diào)用SystemConfig的readPermissions()完成權(quán)限的讀取
SystemConfig systemConfig = SystemConfig.getInstance();
synchronized (mInstallLock) {
// writer
synchronized (mPackages) {
// 啟動"PackageManager"線程，負責apk的安裝灭必、卸載
mHandlerThread = new ServiceThread(TAG,
Process.THREAD_PRIORITY_BACKGROUND, true /*allowIo*/);
mHandlerThread.start();
// 應(yīng)用handler
mHandler = new PackageHandler(mHandlerThread.getLooper());
// 進程記錄handler
mProcessLoggingHandler = new ProcessLoggingHandler();
// Watchdog監(jiān)聽ServiceThread是否超時：10分鐘
Watchdog.getInstance().addThread(mHandler, WATCHDOG_TIMEOUT);
// Instant應(yīng)用注冊
mInstantAppRegistry = new InstantAppRegistry(this);
// 共享lib庫配置
ArrayMap<String, SystemConfig.SharedLibraryEntry> libConfig
= systemConfig.getSharedLibraries();
final int builtInLibCount = libConfig.size();
for (int i = 0; i < builtInLibCount; i++) {
String name = libConfig.keyAt(i);
SystemConfig.SharedLibraryEntry entry = libConfig.valueAt(i);
addBuiltInSharedLibraryLocked(entry.filename, name);
}
...
// 讀取安裝相關(guān)SELinux策略
SELinuxMMAC.readInstallPolicy();
// 返回棧加載
FallbackCategoryProvider.loadFallbacks();
//讀取并解析/data/system下的XML文件
mFirstBoot = !mSettings.readLPw(sUserManager.getUsers(false));
// 清理代碼路徑不存在的孤立軟件包
final int packageSettingCount = mSettings.mPackages.size();
for (int i = packageSettingCount - 1; i >= 0; i--) {
PackageSetting ps = mSettings.mPackages.valueAt(i);
if (!isExternal(ps) && (ps.codePath == null || !ps.codePath.exists())
&& mSettings.getDisabledSystemPkgLPr(ps.name) != null) {
mSettings.mPackages.removeAt(i);
mSettings.enableSystemPackageLPw(ps.name);
}
}
// 如果不是首次啟動狞谱，也不是CORE應(yīng)用，則拷貝預(yù)編譯的DEX文件
if (!mOnlyCore && mFirstBoot) {
requestCopyPreoptedFiles();
}
...
} // synchronized (mPackages)
}
}
readLPW()會掃描下面5個文件
/data/system/packages.xml/data/system/packages-backup.xml/data/system/packages.list/data/system/packages-stopped.xml/data/system/packages-stopped-backup.xml
文件共分為三組禁漓，簡單的作用描述如下：
packages.xml：PKMS 掃描完目標文件夾后會創(chuàng)建該文件跟衅。當系統(tǒng)進行程序安裝、卸載和更新等操作時播歼，均會更新該文件伶跷。該文件保存了系統(tǒng)中與 package 相關(guān)的一些信息。
packages.list：描述系統(tǒng)中存在的所有非系統(tǒng)自帶的 APK 的信息秘狞。當這些程序有變動時叭莫，PKMS 就會更新該文件。
packages-stopped.xml：從系統(tǒng)自帶的設(shè)置程序中進入應(yīng)用程序頁面烁试，然后在選擇強制停止（ForceStop）某個應(yīng)用時雇初，系統(tǒng)會將該應(yīng)用的相關(guān)信息記錄到此文件中。也就是該文件保存系統(tǒng)中被用戶強制停止的 Package 的信息减响。
這些目錄的指向靖诗，都在Settings中的構(gòu)造函數(shù)完成， 如下所示支示，得到目錄后調(diào)用readLPw()進行掃描
Settings(File dataDir, PermissionSettings permission,
Object lock) {
mLock = lock;
mPermissions = permission;
mRuntimePermissionsPersistence = new RuntimePermissionPersistence(mLock);
mSystemDir = new File(dataDir, "system"); //mSystemDir指向目錄"/data/system"
mSystemDir.mkdirs(); //創(chuàng)建 "/data/system"
//設(shè)置權(quán)限
FileUtils.setPermissions(mSystemDir.toString(),
FileUtils.S_IRWXU|FileUtils.S_IRWXG
|FileUtils.S_IROTH|FileUtils.S_IXOTH,
-1, -1);
//(1)指向目錄"/data/system/packages.xml"
mSettingsFilename = new File(mSystemDir, "packages.xml");
//(2)指向目錄"/data/system/packages-backup.xml"
mBackupSettingsFilename = new File(mSystemDir, "packages-backup.xml");
//(3)指向目錄"/data/system/packages.list"
mPackageListFilename = new File(mSystemDir, "packages.list");
FileUtils.setPermissions(mPackageListFilename, 0640, SYSTEM_UID, PACKAGE_INFO_GID);
//(4)指向目錄"/data/system/packages-stopped.xml"
mStoppedPackagesFilename = new File(mSystemDir, "packages-stopped.xml");
//(5)指向目錄"/data/system/packages-stopped-backup.xml"
mBackupStoppedPackagesFilename = new File(mSystemDir, "packages-stopped-backup.xml");
}
解析上面這幾個xml的文件內(nèi)容刊橘，建立對應(yīng)的數(shù)據(jù)結(jié)構(gòu)
[Settings.java]
boolean readLPw(@NonNull List<UserInfo> users) {
FileInputStream str = null;
...
if (str == null) {
str = new FileInputStream(mSettingsFilename);
}
//解析"/data/system/packages.xml"
XmlPullParser parser = Xml.newPullParser();
parser.setInput(str, StandardCharsets.UTF_8.name());
int type;
while ((type = parser.next()) != XmlPullParser.START_TAG
&& type != XmlPullParser.END_DOCUMENT) {
;
}
int outerDepth = parser.getDepth();
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
//根據(jù)XML的各個節(jié)點進行各種操作，例如讀取權(quán)限颂鸿、shared-user等
String tagName = parser.getName();
if (tagName.equals("package")) {
readPackageLPw(parser);
} else if (tagName.equals("permissions")) {
mPermissions.readPermissions(parser);
} else if (tagName.equals("permission-trees")) {
mPermissions.readPermissionTrees(parser);
} else if (tagName.equals("shared-user")) {
readSharedUserLPw(parser);
}...
}
str.close();
...
return true;
}
創(chuàng)建SharedUserSetting對象并添加到Settings的成員變量mSharedUsers中促绵，在Android系統(tǒng)中，多個package通過設(shè)置shareUserid屬性可以運行在同一進程嘴纺，共享同一個UID败晴。
mSettings.addSharedUserLPw("android.uid.system", //字符串
Process.SYSTEM_UID, //系統(tǒng)進程使用的用戶id，值為1000
ApplicationInfo.FLAG_SYSTEM, //標志系統(tǒng) Package
ApplicationInfo.PRIVATE_FLAG_PRIVILEGED); //特權(quán)系統(tǒng)應(yīng)用
SharedUserSetting addSharedUserLPw(String name, int uid, int pkgFlags, int pkgPrivateFlags) {
//mSharedUsers 是一個 HashMap颖医，key 為字符串位衩，值為 SharedUserSetting 對象
SharedUserSetting s = mSharedUsers.get(name);
if (s != null) {
if (s.userId == uid) {
return s;
}
PackageManagerService.reportSettingsProblem(Log.ERROR,
"Adding duplicate shared user, keeping first: " + name);
return null;
}
//創(chuàng)建一個新的 SharedUserSetting 對象裆蒸，并設(shè)置的 userId 為 uid
s = new SharedUserSetting(name, pkgFlags, pkgPrivateFlags);
s.userId = uid;
if (registerExistingAppIdLPw(uid, s, name)) {
mSharedUsers.put(name, s);//將name與s鍵值對添加到mSharedUsers中保存
return s;
}
return null;
}
階段2：BOOT_PROGRESS_PMS_SYSTEM_SCAN_START
主要工作：
- 從init.rc中獲取環(huán)境變量BOOTCLASSPATH和SYSTEMSERVERCLASSPATH熔萧；
- 對于舊版本升級的情況，將安裝時獲取權(quán)限變更為運行時申請權(quán)限
- 掃描system/vendor/product/odem/oem 等目錄的priv-app ,app ,overlay包
- 清除安裝時臨時文件以及其他不必要的信息。
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
synchronized (mInstallLock) {
synchronized (mPackages) {
// 記錄掃描開始時間
long startTime = SystemClock.uptimeMillis();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
startTime);
//獲取環(huán)境變量佛致，init.rc
final String bootClassPath = System.getenv("BOOTCLASSPATH");
final String systemServerClassPath = System.getenv("SYSTEMSERVERCLASSPATH");
...
// 獲取system/framework目錄
File frameworkDir = new File(Environment.getRootDirectory(), "framework");
// 獲取內(nèi)部版本
final VersionInfo ver = mSettings.getInternalVersion();
// 判斷fingerprint是否有更新
mIsUpgrade = !Build.FINGERPRINT.equals(ver.fingerprint);
...
// 對于Android M之前版本升級上來的情況贮缕，需將系統(tǒng)應(yīng)用程序權(quán)限從安裝升級到運行時
mPromoteSystemApps =
mIsUpgrade && ver.sdkVersion <= Build.VERSION_CODES.LOLLIPOP_MR1;
// 對于Android N之前版本升級上來的情況，需像首次啟動一樣處理package
mIsPreNUpgrade = mIsUpgrade && ver.sdkVersion < Build.VERSION_CODES.N;
mIsPreNMR1Upgrade = mIsUpgrade && ver.sdkVersion < Build.VERSION_CODES.N_MR1;
mIsPreQUpgrade = mIsUpgrade && ver.sdkVersion < Build.VERSION_CODES.Q;
// 在掃描之前保存預(yù)先存在的系統(tǒng)package的名稱俺榆，不希望自動為新系統(tǒng)應(yīng)用授予運行時權(quán)限
if (mPromoteSystemApps) {
Iterator<PackageSetting> pkgSettingIter = mSettings.mPackages.values().iterator();
while (pkgSettingIter.hasNext()) {
PackageSetting ps = pkgSettingIter.next();
if (isSystemApp(ps)) {
mExistingSystemPackages.add(ps.name);
}
}
}
// 準備解析package的緩存
mCacheDir = preparePackageParserCache();
// 設(shè)置flag感昼，而不在掃描安裝時更改文件路徑
int scanFlags = SCAN_BOOTING | SCAN_INITIAL;
...
//掃描以下路徑：
/vendor/overlay、/product/overlay罐脊、/product_services/overlay定嗓、/odm/overlay、/oem/overlay萍桌、/system/framework
/system/priv-app宵溅、/system/app、/vendor/priv-app上炎、/vendor/app恃逻、/odm/priv-app、/odm/app藕施、/oem/app寇损、/oem/priv-app、
/product/priv-app裳食、/product/app矛市、/product_services/priv-app、/product_services/app胞谈、/product_services/priv-app
scanDirTracedLI(new File(VENDOR_OVERLAY_DIR),...);
scanDirTracedLI(new File(PRODUCT_OVERLAY_DIR),...);
scanDirTracedLI(new File(PRODUCT_SERVICES_OVERLAY_DIR),...);
scanDirTracedLI(new File(ODM_OVERLAY_DIR),...);
scanDirTracedLI(new File(OEM_OVERLAY_DIR),...);
...
final List<String> possiblyDeletedUpdatedSystemApps = new ArrayList<>();
final List<String> stubSystemApps = new ArrayList<>();
// 刪掉不存在的package
if (!mOnlyCore) {
final Iterator<PackageParser.Package> pkgIterator = mPackages.values().iterator();
while (pkgIterator.hasNext()) {
final PackageParser.Package pkg = pkgIterator.next();
if (pkg.isStub) {
stubSystemApps.add(pkg.packageName);
}
}
final Iterator<PackageSetting> psit = mSettings.mPackages.values().iterator();
while (psit.hasNext()) {
PackageSetting ps = psit.next();
// 如果不是系統(tǒng)應(yīng)用尘盼，則不被允許disable
if ((ps.pkgFlags & ApplicationInfo.FLAG_SYSTEM) == 0) {
continue;
}
// 如果應(yīng)用被掃描，則不允許被擦除
final PackageParser.Package scannedPkg = mPackages.get(ps.name);
if (scannedPkg != null) {
// 如果系統(tǒng)應(yīng)用被掃描且存在disable應(yīng)用列表中烦绳，則只能通過OTA升級添加
if (mSettings.isDisabledSystemPackageLPr(ps.name)) {
...
removePackageLI(scannedPkg, true);
mExpectingBetter.put(ps.name, ps.codePath);
}
continue;
}
...
}
}
// 刪除臨時文件
deleteTempPackageFiles();
// 刪除沒有關(guān)聯(lián)應(yīng)用的共享UID標識
mSettings.pruneSharedUsersLPw();
...
}
...
}
...
}
說明下:[system/app/與system/priv-app/的區(qū)別] 在system/priv-app目錄主要是存放手機廠商定制的系統(tǒng)的系統(tǒng)級應(yīng)用卿捎，比如phone app,settings app，systemui app等径密，這些應(yīng)用需要系統(tǒng)及權(quán)限午阵，而又不能被用戶卸載掉。這個目錄是在Android KitKat新增加的分區(qū)享扔。在KitKat之前版本在系統(tǒng)分區(qū)的所有apks都可以使用系統(tǒng)權(quán)限底桂，這個更改使手機廠商能夠更好的控制捆綁軟件對敏感權(quán)限的訪問。手機廠商在定制一些系統(tǒng)軟件的時候軟件也會需要專門給priv-app添加selinux policy惧眠。當然應(yīng)用需要獲取系統(tǒng)權(quán)限還有其他的辦法籽懦，在AndroidManifest.xml文件中添加 android:sharedUserId="android.uid.sysytem",同時給該apk添加系統(tǒng)簽名，比如小米手機就需要給apk添加小米的系統(tǒng)權(quán)限氛魁。
階段3:BOOT_PROGRESS_PMS_DATA_SCAN_START
主要工作：解析核心應(yīng)用暮顺，處理data目錄下的應(yīng)用信息，更新捶码，刪除不必要的數(shù)據(jù)惫恼。
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
synchronized (mInstallLock) {
synchronized (mPackages) {
...
if (!mOnlyCore) {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
SystemClock.uptimeMillis());
//掃描/data/app 目錄
scanDirTracedLI(sAppInstallDir, 0, scanFlags | SCAN_REQUIRE_KNOWN, 0);
...
// Remove disable package settings for updated system apps that were
// removed via an OTA. If the update is no longer present, remove the
// app completely. Otherwise, revoke their system privileges.
// 移除通過OTA刪除的更新系統(tǒng)應(yīng)用程序的禁用package設(shè)置
// 如果更新不再存在档押，則完全刪除該應(yīng)用祈纯。否則，撤消其系統(tǒng)權(quán)限
for (int i = possiblyDeletedUpdatedSystemApps.size() - 1; i >= 0; --i) {
final String packageName = possiblyDeletedUpdatedSystemApps.get(i);
final PackageParser.Package pkg = mPackages.get(packageName);
final String msg;
// remove from the disabled system list; do this first so any future
// scans of this package are performed without this state
mSettings.removeDisabledSystemPackageLPw(packageName);
...
}
/* Make sure all system apps that we expected to appear on the userdata partition actually showed up. If they never
appeared, crawl back and revive the system version.
*/
// 確保期望在userdata分區(qū)上顯示的所有系統(tǒng)應(yīng)用程序?qū)嶋H顯示
// 如果從未出現(xiàn)過腕窥，需要回滾以恢復(fù)系統(tǒng)版本
for (int i = 0; i < mExpectingBetter.size(); i++) {
final String packageName = mExpectingBetter.keyAt(i);
if (!mPackages.containsKey(packageName)) {
final File scanFile = mExpectingBetter.valueAt(i);
...
mSettings.enableSystemPackageLPw(packageName);
try {
//掃描APK
scanPackageTracedLI(scanFile, reparseFlags, rescanFlags, 0, null);
} catch (PackageManagerException e) {
Slog.e(TAG, "Failed to parse original system package: "
+ e.getMessage());
}
}
}
// Uncompress and install any stubbed system applications.
// This must be done last to ensure all stubs are replaced or disabled.
// 解壓縮并安裝任何存根系統(tǒng)應(yīng)用程序掀淘。必須最后執(zhí)行此操作以確保替換或禁用所有存根
installSystemStubPackages(stubSystemApps, scanFlags);
...
// 獲取storage manager包名
mStorageManagerPackage = getStorageManagerPackageName();
// Resolve protected action filters. Only the setup wizard is allowed to
// have a high priority filter for these actions.
// 解決受保護的action過濾器革娄。只允許setup wizard（開機向?qū)В檫@些action設(shè)置高優(yōu)先級過濾器
mSetupWizardPackage = getSetupWizardPackageName();
...
// Now that we know all of the shared libraries, update all clients to have
// the correct library paths.
// 更新客戶端以確保持有正確的共享庫路徑
updateAllSharedLibrariesLocked(null, Collections.unmodifiableMap(mPackages));
...
// 讀取并更新要保留的package的上次使用時間
mPackageUsage.read(mPackages);
mCompilerStats.read();
}
}
}
}
階段四：BOOT_PROGRESS_PMS_SCAN_END
主要工作：
- sdk版本變更拦惋，更新權(quán)限
- OTA升級后首次啟動安寺，清除不必要的緩存數(shù)據(jù)
- 權(quán)限等默認更新后挑庶，清理相關(guān)數(shù)據(jù)
- 更新package.xml
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
synchronized (mInstallLock) {
synchronized (mPackages) {
...
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
// If the platform SDK has changed since the last time we booted,
// we need to re-grant app permission to catch any new ones that
// appear. This is really a hack, and means that apps can in some
// cases get permissions that the user didn't initially explicitly
// allow... it would be nice to have some better way to handle
// this situation.
// 如果自上次啟動以來迎捺，平臺SDK已改變凳枝，則需要重新授予應(yīng)用程序權(quán)限以捕獲出現(xiàn)的任何新權(quán)限
final boolean sdkUpdated = (ver.sdkVersion != mSdkVersion);
mPermissionManager.updateAllPermissions(
StorageManager.UUID_PRIVATE_INTERNAL, sdkUpdated, mPackages.values(),
mPermissionCallback);
...
// If this is the first boot or an update from pre-M, and it is a normal
// boot, then we need to initialize the default preferred apps across
// all defined users.
// 如果這是第一次啟動或來自Android M之前的版本的升級岖瑰，并且它是正常啟動，那需要在所有已定義的用戶中初始化默認的首選應(yīng)用程序
if (!onlyCore && (mPromoteSystemApps || mFirstBoot)) {
for (UserInfo user : sUserManager.getUsers(true)) {
mSettings.applyDefaultPreferredAppsLPw(user.id);
primeDomainVerificationsLPw(user.id);
}
}
// Prepare storage for system user really early during boot,
// since core system apps like SettingsProvider and SystemUI
// can't wait for user to start
// 在啟動期間為系統(tǒng)用戶準備存儲率挣，因為像SettingsProvider和SystemUI這樣的核心系統(tǒng)應(yīng)用程序無法等待用戶啟動
final int storageFlags;
if (StorageManager.isFileEncryptedNativeOrEmulated()) {
storageFlags = StorageManager.FLAG_STORAGE_DE;
} else {
storageFlags = StorageManager.FLAG_STORAGE_DE | StorageManager.FLAG_STORAGE_CE;
}
...
// If this is first boot after an OTA, and a normal boot, then
// we need to clear code cache directories.
// Note that we do *not* clear the application profiles. These remain valid
// across OTAs and are used to drive profile verification (post OTA) and
// profile compilation (without waiting to collect a fresh set of profiles).
// 如果是在OTA之后首次啟動娃圆，并且正常啟動蛾茉，那需要清除代碼緩存目錄谦炬，但不清除應(yīng)用程序配置文件
if (mIsUpgrade && !onlyCore) {
Slog.i(TAG, "Build fingerprint changed; clearing code caches");
for (int i = 0; i < mSettings.mPackages.size(); i++) {
final PackageSetting ps = mSettings.mPackages.valueAt(i);
if (Objects.equals(StorageManager.UUID_PRIVATE_INTERNAL, ps.volumeUuid)) {
// No apps are running this early, so no need to freeze
clearAppDataLIF(ps.pkg, UserHandle.USER_ALL,
FLAG_STORAGE_DE | FLAG_STORAGE_CE | FLAG_STORAGE_EXTERNAL
| Installer.FLAG_CLEAR_CODE_CACHE_ONLY);
}
}
ver.fingerprint = Build.FINGERPRINT;
}
// Grandfather existing (installed before Q) non-system apps to hide
// their icons in launcher.
//安裝Android-Q前的非系統(tǒng)應(yīng)用程序在Launcher中隱藏他們的圖標
if (!onlyCore && mIsPreQUpgrade) {
Slog.i(TAG, "Whitelisting all existing apps to hide their icons");
int size = mSettings.mPackages.size();
for (int i = 0; i < size; i++) {
final PackageSetting ps = mSettings.mPackages.valueAt(i);
if ((ps.pkgFlags & ApplicationInfo.FLAG_SYSTEM) != 0) {
continue;
}
ps.disableComponentLPw(PackageManager.APP_DETAILS_ACTIVITY_CLASS_NAME,
UserHandle.USER_SYSTEM);
}
}
// clear only after permissions and other defaults have been updated
// 僅在權(quán)限或其它默認配置更新后清除
mExistingSystemPackages.clear();
mPromoteSystemApps = false;
...
// All the changes are done during package scanning.
// 所有變更均在掃描過程中完成
ver.databaseVersion = Settings.CURRENT_DATABASE_VERSION;
// can downgrade to reader
//降級去讀取
mSettings.writeLPr();
}
}
}
階段五：BOOT_PROGRESS_PMS_READY
主要工作有：
- 創(chuàng)建PackageInstallerService對
- GC回收內(nèi)存
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
synchronized (mInstallLock) {
synchronized (mPackages) {
...
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
...
// PermissionController hosts default permission granting and role management, so it's a critical part of the core system.
//PermissionController 持有默認的權(quán)限授予和角色管理，所以這是核心系統(tǒng)的一個關(guān)鍵部分叫搁。
mRequiredPermissionControllerPackage = getRequiredPermissionControllerLPr();
...
updateInstantAppInstallerLocked(null);
// Read and update the usage of dex files.
// Do this at the end of PM init so that all the packages have their data directory reconciled.
// At this point we know the code paths of the packages, so we can validate
// the disk file and build the internal cache.
// The usage file is expected to be small so loading and verifying it should take a fairly small time compare to the other activities (e.g. package scanning).
// 閱讀并更新dex文件的用法
// 在PM init結(jié)束時執(zhí)行此操作渴逻，以便所有程序包都已協(xié)調(diào)其數(shù)據(jù)目錄
// 此時知道了包的代碼路徑惨奕，因此可以驗證磁盤文件并構(gòu)建內(nèi)部緩存
// 使用文件預(yù)計很小梨撞，因此與其他活動（例如包掃描）相比，加載和驗證它應(yīng)該花費相當小的時間
final Map<Integer, List<PackageInfo>> userPackages = new HashMap<>();
for (int userId : userIds) {
userPackages.put(userId, getInstalledPackages(/*flags*/ 0, userId).getList());
}
mDexManager.load(userPackages);
if (mIsUpgrade) {
MetricsLogger.histogram(null, "ota_package_manager_init_time",
(int) (SystemClock.uptimeMillis() - startTime));
}
}
}
...
// Now after opening every single application zip, make sure they are all flushed. Not really needed, but keeps things nice and tidy.
// 打開應(yīng)用之后，及時回收處理
Runtime.getRuntime().gc();
// The initial scanning above does many calls into installd while
// holding the mPackages lock, but we're mostly interested in yelling
// once we have a booted system.
// 上面的初始掃描在持有mPackage鎖的同時對installd進行了多次調(diào)用
mInstaller.setWarnIfHeld(mPackages);
...
}
DEX優(yōu)化
檢查是否需要去更新Packages并進行dex優(yōu)化嗜侮，如果沒有OTA升級啥容，沒有大版本升級咪惠，沒有清除dalvik虛擬機緩存，可以去更新packages覆醇。最終調(diào)用的是Installer的dexopt進行優(yōu)化
PKMS.java#updatePackagesIfNeeded()
更新packages的優(yōu)先級：core app> system app > other app,調(diào)用performDexOptUpgrade()進行系統(tǒng)更新
public void updatePackagesIfNeeded() {
//只有system或是root用戶才有權(quán)限請求 package update
enforceSystemOrRoot("Only the system can request package update");
//(1)判斷有沒有進行OTA升級永脓，我們需要在OTA后重新提取常摧。
boolean causeUpgrade = isDeviceUpgrading();
//(2)是否是第一次啟動或是系統(tǒng)大版本升級
boolean causeFirstBoot = isFirstBoot() || mIsPreNUpgrade;
// We need to re-extract after a pruned cache, as AoT-ed files will be out of date.
//(3)判斷是否有清除過dalvik虛擬機的緩存
boolean causePrunedCache = VMRuntime.didPruneDalvikCache();
//(4)如果上面的三個都沒有落午，那么就不進行任何操作
if (!causeUpgrade && !causeFirstBoot && !causePrunedCache) {
return;
}
List<PackageParser.Package> pkgs;
synchronized (mPackages) {
//(5)按照package的優(yōu)先級進行排序，core app >system app > other app
pkgs = PackageManagerServiceUtils.getPackagesForDexopt(mPackages.values(), this);
}
final long startTime = System.nanoTime(); //記錄開始時間
//進行dex優(yōu)化界拦，
final int[] stats = performDexOptUpgrade(pkgs, mIsPreNUpgrade /* showDialog */,
causeFirstBoot ? REASON_FIRST_BOOT : REASON_BOOT,
false /* bootComplete */);
...
}
PackageManagerService.java#performDexOptUpgrade()
判斷是否需要對package進行更新享甸，如果需要那么更新會按照優(yōu)先級完成dex優(yōu)化枪萄，最終調(diào)用Install的dexopt進行dex優(yōu)化猫妙。
private int[] performDexOptUpgrade(List<PackageParser.Package> pkgs, boolean showDialog,
final int compilationReason, boolean bootComplete) {
...
//循環(huán)取出packages割坠，進行優(yōu)化
for (PackageParser.Package pkg : pkgs) {
numberOfPackagesVisited++;
boolean useProfileForDexopt = false;
//第一次啟動或是ota升級之后并且是系統(tǒng)應(yīng)用才會進行odex
if ((isFirstBoot() || isDeviceUpgrading()) && isSystemApp(pkg)) {
...
}
...
//最終是調(diào)用 mInstaller.dexopt 完成優(yōu)化的彼哼，installd守護進程敢朱，installer安裝器和Installd通信
int primaryDexOptStaus = performDexOptTraced(new DexoptOptions(
pkg.packageName,
pkgCompilationReason,
dexoptFlags));
switch (primaryDexOptStaus) {
case PackageDexOptimizer.DEX_OPT_PERFORMED:
numberOfPackagesOptimized++; //odex優(yōu)化完成的應(yīng)用
break;
case PackageDexOptimizer.DEX_OPT_SKIPPED:
numberOfPackagesSkipped++; //跳過的應(yīng)用
break;
case PackageDexOptimizer.DEX_OPT_FAILED:
numberOfPackagesFailed++; //失敗的應(yīng)用
break;
default:
Log.e(TAG, "Unexpected dexopt return code " + primaryDexOptStaus);
break;
}
}
return new int[] { numberOfPackagesOptimized, numberOfPackagesSkipped,
numberOfPackagesFailed };
}
磁盤維護
磁盤維護最終調(diào)用的是vold進行的fstrim進行清理操作
PackageManagerService.java#performFstrimIfNeeded()
主要執(zhí)行磁盤清理工作拴签，釋放磁盤空間
public void performFstrimIfNeeded() {
//只有system或是root用戶才有權(quán)限請求fstrim
enforceSystemOrRoot("Only the system can request fstrim");
// Before everything else, see whether we need to fstrim.
//在其他事情之前蚓哩，看看我們是否需要fstrim
try {
//獲取StorageManager對象
IStorageManager sm = PackageHelper.getStorageManager();
if (sm != null) {
boolean doTrim = false;
//獲取執(zhí)行FTRIM間隔，默認是3天喜颁，可以通過setting provider更改這個時間
long interval = android.provider.Settings.Global.getLong(
mContext.getContentResolver(),
android.provider.Settings.Global.FSTRIM_MANDATORY_INTERVAL,
DEFAULT_MANDATORY_FSTRIM_INTERVAL);
if (interval > 0) {
final long timeSinceLast = System.currentTimeMillis() - sm.lastMaintenance();
if (timeSinceLast > interval) {
doTrim = true; //如果超過了三天就進行磁盤清理
Slog.w(TAG, "No disk maintenance in " + timeSinceLast
+ "; running immediately");
}
}
if (doTrim) {
final boolean dexOptDialogShown;
synchronized (mPackages) {
dexOptDialogShown = mDexOptDialogShown;
}
//如果不是第一次啟動半开，顯示一個提示框
if (!isFirstBoot() && dexOptDialogShown) {
try {
ActivityManager.getService().showBootMessage(
mContext.getResources().getString(
R.string.android_upgrading_fstrim), true);
} catch (RemoteException e) {
}
}
// 這里的sm是 StorageManagerService寂拆，發(fā)送消息H_FSTRIM給handler漓库，然后再向vold發(fā)送fstrim命
sm.runMaintenance();
}
} else {
Slog.e(TAG, "storageManager service unavailable!");
}
} catch (RemoteException e) {
// Can't happen; StorageManagerService is local
}
}
PKMS準備就緒
PackageManagerService.java#systemReady()
systemReady主要完成默認授權(quán)和更新package的信息渺蒿，通知等待pms的一些組件彪薛。
public void systemReady() {
//只有system或是root用戶才有權(quán)限 聲稱system已經(jīng)ready
enforceSystemOrRoot("Only the system can claim the system is ready");
ContentObserver co = new ContentObserver(mHandler) {
...
};
co.onChange(true); //注冊一個監(jiān)聽
...
synchronized (mPackages) {
ArrayList<PreferredActivity> removed = new ArrayList<>();
for (int i=0; i<mSettings.mPreferredActivities.size(); i++) {
PreferredIntentResolver pir = mSettings.mPreferredActivities.valueAt(i);
removed.clear();
for (PreferredActivity pa : pir.filterSet()) {
if (!mComponentResolver.isActivityDefined(pa.mPref.mComponent)) {
removed.add(pa);
}
}//移除不存在的先前用戶設(shè)置保存的優(yōu)先選擇的activity組件
if (removed.size() > 0) {
for (int r=0; r<removed.size(); r++) {
PreferredActivity pa = removed.get(r);
Slog.w(TAG, "Removing dangling preferred activity: "
+ pa.mPref.mComponent);
pir.removeFilter(pa);
}
mSettings.writePackageRestrictionsLPr(
mSettings.mPreferredActivities.keyAt(i)); //寫入到文件中
}
}
for (int userId : UserManagerService.getInstance().getUserIds()) {
if (!mSettings.areDefaultRuntimePermissionsGrantedLPr(userId)) {
grantPermissionsUserIds = ArrayUtils.appendInt(
grantPermissionsUserIds, userId);
}
}
}
sUserManager.systemReady(); //多用戶服務(wù) systemReady
//升級所有已獲取的默認權(quán)限
for (int userId : grantPermissionsUserIds) {
mDefaultPermissionPolicy.grantDefaultPermissions(userId); //默認授權(quán)操作
}
...
// Now that we've scanned all packages, and granted any default
// permissions, ensure permissions are updated. Beware of dragons if you
// try optimizing this.
synchronized (mPackages) {
mPermissionManager.updateAllPermissions(
StorageManager.UUID_PRIVATE_INTERNAL, false, mPackages.values(),
mPermissionCallback); //更新權(quán)限信息
...
});
}
//注意隨時間變化的外部存儲設(shè)備
final StorageManager storage = mContext.getSystemService(StorageManager.class);
storage.registerListener(mStorageListener);
mInstallerService.systemReady();
mApexManager.systemReady();
mPackageDexOptimizer.systemReady();
...
// Now that we're mostly running, clean up stale users and apps
//清除過期的userid和app
sUserManager.reconcileUsers(StorageManager.UUID_PRIVATE_INTERNAL);
reconcileApps(StorageManager.UUID_PRIVATE_INTERNAL);
mPermissionManager.systemReady();
if (mInstantAppResolverConnection != null) {
mContext.registerReceiver(new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
mInstantAppResolverConnection.optimisticBind();
mContext.unregisterReceiver(this);
}
}, new IntentFilter(Intent.ACTION_BOOT_COMPLETED));
}
if (!isFirstBoot()) {
Slog.i(TAG, "enablePackageStoppedPolicy");
synchronized (mPackages) {
PackageManagerServiceUtilsZTE.enablePackageStoppedPolicy(mPackages.values(), this);
}
}
mModuleInfoProvider.systemReady();
// Installer service might attempt to install some packages that have been staged for
// installation on reboot. Make sure this is the last component to be call since the
// installation might require other components to be ready.
mInstallerService.restoreAndApplyStagedSessionIfNeeded();
//update partner app
new Thread(() -> {
updatePartnerAppInFota();
}).start();
}
大概流程就是這樣，完彼妻。
