概述
PackageManagerService是android系统核心服务之一，在Android中非常重要，主要负责的功能如下：
解析AndroidManifest.xml 主要包括AndoridManifest中节点的信息。
扫描本地文件，主要针对apk，主要是系统应用，本地安装应用等。
管理本地apk，主要包括安装和删除等。
启动过程
PKMS服务由SystemServer进行启动，在SystemServer中startBootstrapServices()启动PKMS服务，在调用startOtherServices进行dex优化，磁盘管理等功能，并让PKMS进入systemReady状态。
SystemServer.java#startBootstrapServices()
startBootstrapServices首先启动Installer服务，也就是安装器，随后判断当前的设备是否处于加密状态，如果是则只解析核心应用，接着调用PKMS的静态方法main来创建pkms对象
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)启动Installer
//阻塞等待installd完成启动，以便有机会创建具有适当权限的关键目录，如/data/user。
//我们需要在初始化其他服务之前完成此任务。
Installer installer = mSystemServiceManager.startService(Installer.class);
mActivityManagerService.setInstaller(installer);
...
// Only run "core" apps if we're encrypting the device.
//(2)获取设别是否加密(手机设置密码)，如果设备加密了，则只解析"core"应用，mOnlyCore = true，后面会频繁使用该变量进行条件判断
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)调用main方法初始化PackageManagerService。
mPackageManagerService = PackageManagerService.main(mSystemContext, installer,
mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore);
//PKMS是否是第一次启动
mFirstBoot = mPackageManagerService.isFirstBoot();
//(4)如果设备没有加密，操作它。管理A/B OTA dexopting。
if (!mOnlyCore) {
boolean disableOtaDexopt = SystemProperties.getBoolean("config.disable_otadexopt",
false);
OtaDexoptService.main(mSystemContext, mPackageManagerService);
}
...
}
startOtherServices
- 执行updatePackagesIfNeeded，完成dex优化
- 执行performFstrimIfNeeded 完成磁盘维护
- 调用systemReady 准备就绪
private void startOtherServices() {
...
if (!mOnlyCore) {
...
//(5)如果设备没有加密，执行performDexOptUpgrade，完成dex优化；
mPackageManagerService.updatePackagesIfNeeded();
}
...
//(6) 最终执行performFstrim，完成磁盘维护
mPackageManagerService.performFstrimIfNeeded();
...
//(7)PKMS准备就绪
mPackageManagerService.systemReady();
...
}
PackageManagerService.java#main()
main函数主要工作：
- 检查Package编译相关系统属性
- 调用PackageManagerService构造方法
- 启动部分应用服务于多用户场景
- 往ServiceManager中注册
package和package_native。
public static PackageManagerService main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
// (1)检查Package编译相关系统属性
PackageManagerServiceCompilerMapping.checkProperties();
//(2)调用PackageManagerService构造方法
PackageManagerService m = new PackageManagerService(context, installer,
factoryTest, onlyCore);
//(3)启用部分应用服务于多用户场景
m.enableSystemUserPackages();
//(4)往ServiceManager中注册”package”和”package_native”。
ServiceManager.addService("package", m);
final PackageManagerNative pmn = m.new PackageManagerNative();
ServiceManager.addService("package_native", pmn);
return m;
}
PKMS初始化时的核心部分为PackageManagerService()构造函数的内容，我们接下来就来分析该流程。
PKMS构造函数分析
主要有两个重要的锁(mInstallLock,mPackages)和五个阶段构成。
mPackages:用来解析内存中所有apk的package信息以及相关状态。
五个阶段：
阶段1：BOOT_PROGRESS_PMS_START
阶段2：BOOT_PROGRESS_PMS_SYSTEM_SCAN_START
阶段3：BOOT_PROGRESS_PMS_DATA_SCAN_START
阶段4：BOOT_PROGRESS_PMS_SCAN_END
阶段5：BOOT_PROGRESS_PMS_READY
PKMS服务也是通过binder进行通信，IPackageManager.aidl由工具转换后自动生成binder的服务端IPackageManager.Stub和客户端IPackageManager.Stub.Proxy。Binder服务端：PackageManagerService继承于IPackageManager.Stub
Binder客户端：ApplicationPackageManager的成员变量mPM继承于IPackageManager.Stub.Proxy;本身APM继承于PackageManager对象。
PackageManagerService.java
IPacakgeManager.Stub 是IPackageManager.aidl自动生成的，正好也说明PKMS是service端，通过Binder交互
public class PackageManagerService extends IPackageManager.Stub
implements PackageSender
PackageManagerService()构造函数
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
...
//阶段1：BOOT_PROGRESS_PMS_START
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
SystemClock.uptimeMillis());
//阶段2：BOOT_PROGRESS_PMS_SYSTEM_SCAN_START
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
startTime);
...
//阶段3：BOOT_PROGRESS_PMS_DATA_SCAN_START
if (!mOnlyCore) {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
SystemClock.uptimeMillis());
}
...
//阶段4：BOOT_PROGRESS_PMS_SCAN_END
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
...
//阶段5：BOOT_PROGRESS_PMS_READY
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
}
阶段1：BOOT_PROGRESS_PMS_START
主要工作：
构造DisplayMetrics，保存分辨率等相关信息
创建Installer对象 与InstallId交互
创建mPermissionManager对象，进行权限管理
构造Settings类，保存安装包信息，清除路径不存在的孤立应用，主要涉及/data/system目录下的packages.xml,package-backup.xml,packages.list,packages-stopped.xml,packages-stopped-backup.xml等文件。
构造PackageDexOptimizer及DexManager类，处理dex优化；
创建SystemConfig实例，获取系统配置信息，配置共享lib库
创建PackageManager的handler线程，循环处理外部安装相关消息。
public PackageManagerService(...) {
LockGuard.installLock(mPackages, LockGuard.INDEX_PACKAGES);
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
SystemClock.uptimeMillis());
mContext = context;
mFactoryTest = factoryTest; // 一般为false，即非工厂生产模式
mOnlyCore = onlyCore; //标记是否只加载核心服务
mMetrics = new DisplayMetrics(); // 分辨率配置
mInstaller = installer; //保存installer对象
// Create sub-components that provide services / data. Order here is important.
//创建提供服务/数据的子组件。这里的顺序很重要,使用到了两个重要的同步锁：mInstallLock、mPackages
synchronized (mInstallLock) {
synchronized (mPackages) {
// Expose private service for system components to use.
// 公开系统组件使用的私有服务
// 本地服务
LocalServices.addService(
PackageManagerInternal.class, new PackageManagerInternalImpl());
// 多用户管理服务
sUserManager = new UserManagerService(context, this,
new UserDataPreparer(mInstaller, mInstallLock, mContext, mOnlyCore), mPackages);
mComponentResolver = new ComponentResolver(sUserManager,
LocalServices.getService(PackageManagerInternal.class),
mPackages);
// 权限管理服务
mPermissionManager = PermissionManagerService.create(context,
mPackages /*externalLock*/);
mDefaultPermissionPolicy = mPermissionManager.getDefaultPermissionGrantPolicy();
//创建Settings对象
mSettings = new Settings(Environment.getDataDirectory(),
mPermissionManager.getPermissionSettings(), mPackages);
}
}
// 添加system, phone, log, nfc, bluetooth, shell，se，networkstack 这8种shareUserId到mSettings；
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优化
mPackageDexOptimizer = new PackageDexOptimizer(installer, mInstallLock, context,
"*dexopt*");
mDexManager = new DexManager(mContext, this, mPackageDexOptimizer, installer, mInstallLock);
// ART虚拟机管理服务
mArtManagerService = new ArtManagerService(mContext, this, installer, mInstallLock);
mMoveCallbacks = new MoveCallbacks(FgThread.get().getLooper());
mViewCompiler = new ViewCompiler(mInstallLock, mInstaller);
// 权限变化监听器
mOnPermissionChangeListeners = new OnPermissionChangeListeners(
FgThread.get().getLooper());
mProtectedPackages = new ProtectedPackages(mContext);
mApexManager = new ApexManager(context);
// 获取默认分辨率
getDefaultDisplayMetrics(context, mMetrics);
//拿到SystemConfig()的对象，其中会调用SystemConfig的readPermissions()完成权限的读取
SystemConfig systemConfig = SystemConfig.getInstance();
synchronized (mInstallLock) {
// writer
synchronized (mPackages) {
// 启动"PackageManager"线程，负责apk的安装、卸载
mHandlerThread = new ServiceThread(TAG,
Process.THREAD_PRIORITY_BACKGROUND, true /*allowIo*/);
mHandlerThread.start();
// 应用handler
mHandler = new PackageHandler(mHandlerThread.getLooper());
// 进程记录handler
mProcessLoggingHandler = new ProcessLoggingHandler();
// Watchdog监听ServiceThread是否超时：10分钟
Watchdog.getInstance().addThread(mHandler, WATCHDOG_TIMEOUT);
// Instant应用注册
mInstantAppRegistry = new InstantAppRegistry(this);
// 共享lib库配置
ArrayMap 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);
}
...
// 读取安装相关SELinux策略
SELinuxMMAC.readInstallPolicy();
// 返回栈加载
FallbackCategoryProvider.loadFallbacks();
//读取并解析/data/system下的XML文件
mFirstBoot = !mSettings.readLPw(sUserManager.getUsers(false));
// 清理代码路径不存在的孤立软件包
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);
}
}
// 如果不是首次启动，也不是CORE应用，则拷贝预编译的DEX文件
if (!mOnlyCore && mFirstBoot) {
requestCopyPreoptedFiles();
}
...
} // synchronized (mPackages)
}
}
readLPW()会扫描下面5个文件
/data/system/packages.xml/data/system/packages-backup.xml/data/system/packages.list/data/system/packages-stopped.xml/data/system/packages-stopped-backup.xml
文件共分为三组，简单的作用描述如下：
packages.xml：PKMS 扫描完目标文件夹后会创建该文件。当系统进行程序安装、卸载和更新等操作时，均会更新该文件。该文件保存了系统中与 package 相关的一些信息。
packages.list：描述系统中存在的所有非系统自带的 APK 的信息。当这些程序有变动时，PKMS 就会更新该文件。
packages-stopped.xml：从系统自带的设置程序中进入应用程序页面，然后在选择强制停止（ForceStop）某个应用时，系统会将该应用的相关信息记录到此文件中。也就是该文件保存系统中被用户强制停止的 Package 的信息。
这些目录的指向，都在Settings中的构造函数完成， 如下所示，得到目录后调用readLPw()进行扫描
Settings(File dataDir, PermissionSettings permission,
Object lock) {
mLock = lock;
mPermissions = permission;
mRuntimePermissionsPersistence = new RuntimePermissionPersistence(mLock);
mSystemDir = new File(dataDir, "system"); //mSystemDir指向目录"/data/system"
mSystemDir.mkdirs(); //创建 "/data/system"
//设置权限
FileUtils.setPermissions(mSystemDir.toString(),
FileUtils.S_IRWXU|FileUtils.S_IRWXG
|FileUtils.S_IROTH|FileUtils.S_IXOTH,
-1, -1);
//(1)指向目录"/data/system/packages.xml"
mSettingsFilename = new File(mSystemDir, "packages.xml");
//(2)指向目录"/data/system/packages-backup.xml"
mBackupSettingsFilename = new File(mSystemDir, "packages-backup.xml");
//(3)指向目录"/data/system/packages.list"
mPackageListFilename = new File(mSystemDir, "packages.list");
FileUtils.setPermissions(mPackageListFilename, 0640, SYSTEM_UID, PACKAGE_INFO_GID);
//(4)指向目录"/data/system/packages-stopped.xml"
mStoppedPackagesFilename = new File(mSystemDir, "packages-stopped.xml");
//(5)指向目录"/data/system/packages-stopped-backup.xml"
mBackupStoppedPackagesFilename = new File(mSystemDir, "packages-stopped-backup.xml");
}
解析上面这几个xml的文件内容，建立对应的数据结构
[Settings.java]
boolean readLPw(@NonNull List 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;
}
//根据XML的各个节点进行各种操作，例如读取权限、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;
}
创建SharedUserSetting对象并添加到Settings的成员变量mSharedUsers中，在Android系统中，多个package通过设置shareUserid属性可以运行在同一进程，共享同一个UID。
mSettings.addSharedUserLPw("android.uid.system", //字符串
Process.SYSTEM_UID, //系统进程使用的用户id，值为1000
ApplicationInfo.FLAG_SYSTEM, //标志系统 Package
ApplicationInfo.PRIVATE_FLAG_PRIVILEGED); //特权系统应用
SharedUserSetting addSharedUserLPw(String name, int uid, int pkgFlags, int pkgPrivateFlags) {
//mSharedUsers 是一个 HashMap，key 为字符串，值为 SharedUserSetting 对象
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;
}
//创建一个新的 SharedUserSetting 对象，并设置的 userId 为 uid
s = new SharedUserSetting(name, pkgFlags, pkgPrivateFlags);
s.userId = uid;
if (registerExistingAppIdLPw(uid, s, name)) {
mSharedUsers.put(name, s);//将name与s键值对添加到mSharedUsers中保存
return s;
}
return null;
}
阶段2：BOOT_PROGRESS_PMS_SYSTEM_SCAN_START
主要工作：
- 从init.rc中获取环境变量BOOTCLASSPATH和SYSTEMSERVERCLASSPATH；
- 对于旧版本升级的情况，将安装时获取权限变更为运行时申请权限
- 扫描system/vendor/product/odem/oem 等目录的priv-app ,app ,overlay包
- 清除安装时临时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) {
// 记录扫描开始时间
long startTime = SystemClock.uptimeMillis();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
startTime);
//获取环境变量，init.rc
final String bootClassPath = System.getenv("BOOTCLASSPATH");
final String systemServerClassPath = System.getenv("SYSTEMSERVERCLASSPATH");
...
// 获取system/framework目录
File frameworkDir = new File(Environment.getRootDirectory(), "framework");
// 获取内部版本
final VersionInfo ver = mSettings.getInternalVersion();
// 判断fingerprint是否有更新
mIsUpgrade = !Build.FINGERPRINT.equals(ver.fingerprint);
...
// 对于Android M之前版本升级上来的情况，需将系统应用程序权限从安装升级到运行时
mPromoteSystemApps =
mIsUpgrade && ver.sdkVersion <= Build.VERSION_CODES.LOLLIPOP_MR1;
// 对于Android N之前版本升级上来的情况，需像首次启动一样处理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;
// 在扫描之前保存预先存在的系统package的名称，不希望自动为新系统应用授予运行时权限
if (mPromoteSystemApps) {
Iterator pkgSettingIter = mSettings.mPackages.values().iterator();
while (pkgSettingIter.hasNext()) {
PackageSetting ps = pkgSettingIter.next();
if (isSystemApp(ps)) {
mExistingSystemPackages.add(ps.name);
}
}
}
// 准备解析package的缓存
mCacheDir = preparePackageParserCache();
// 设置flag，而不在扫描安装时更改文件路径
int scanFlags = SCAN_BOOTING | SCAN_INITIAL;
...
//扫描以下路径：
/vendor/overlay、/product/overlay、/product_services/overlay、/odm/overlay、/oem/overlay、/system/framework
/system/priv-app、/system/app、/vendor/priv-app、/vendor/app、/odm/priv-app、/odm/app、/oem/app、/oem/priv-app、
/product/priv-app、/product/app、/product_services/priv-app、/product_services/app、/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 possiblyDeletedUpdatedSystemApps = new ArrayList<>();
final List stubSystemApps = new ArrayList<>();
// 删掉不存在的package
if (!mOnlyCore) {
final Iterator pkgIterator = mPackages.values().iterator();
while (pkgIterator.hasNext()) {
final PackageParser.Package pkg = pkgIterator.next();
if (pkg.isStub) {
stubSystemApps.add(pkg.packageName);
}
}
final Iterator psit = mSettings.mPackages.values().iterator();
while (psit.hasNext()) {
PackageSetting ps = psit.next();
// 如果不是系统应用，则不被允许disable
if ((ps.pkgFlags & ApplicationInfo.FLAG_SYSTEM) == 0) {
continue;
}
// 如果应用被扫描，则不允许被擦除
final PackageParser.Package scannedPkg = mPackages.get(ps.name);
if (scannedPkg != null) {
// 如果系统应用被扫描且存在disable应用列表中，则只能通过OTA升级添加
if (mSettings.isDisabledSystemPackageLPr(ps.name)) {
...
removePackageLI(scannedPkg, true);
mExpectingBetter.put(ps.name, ps.codePath);
}
continue;
}
...
}
}
// 删除临时文件
deleteTempPackageFiles();
// 删除没有关联应用的共享UID标识
mSettings.pruneSharedUsersLPw();
...
}
...
}
...
}
说明下:[system/app/与system/priv-app/的区别] 在system/priv-app目录主要是存放手机厂商定制的系统的系统级应用，比如phone app,settings app，systemui app等，这些应用需要系统及权限，而又不能被用户卸载掉。这个目录是在Android KitKat新增加的分区。在KitKat之前版本在系统分区的所有apks都可以使用系统权限，这个更改使手机厂商能够更好的控制捆绑软件对敏感权限的访问。手机厂商在定制一些系统软件的时候软件也会需要专门给priv-app添加selinux policy。当然应用需要获取系统权限还有其他的办法，在AndroidManifest.xml文件中添加 android:sharedUserId="android.uid.sysytem",同时给该apk添加系统签名，比如小米手机就需要给apk添加小米的系统权限。
阶段3:BOOT_PROGRESS_PMS_DATA_SCAN_START
主要工作：解析核心应用，处理data目录下的应用信息，更新，删除不必要的数据。
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());
//扫描/data/app 目录
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.
// 移除通过OTA删除的更新系统应用程序的禁用package设置
// 如果更新不再存在，则完全删除该应用。否则，撤消其系统权限
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.
*/
// 确保期望在userdata分区上显示的所有系统应用程序实际显示
// 如果从未出现过，需要回滚以恢复系统版本
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 {
//扫描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.
// 解压缩并安装任何存根系统应用程序。必须最后执行此操作以确保替换或禁用所有存根
installSystemStubPackages(stubSystemApps, scanFlags);
...
// 获取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.
// 解决受保护的action过滤器。只允许setup wizard（开机向导）为这些action设置高优先级过滤器
mSetupWizardPackage = getSetupWizardPackageName();
...
// Now that we know all of the shared libraries, update all clients to have
// the correct library paths.
// 更新客户端以确保持有正确的共享库路径
updateAllSharedLibrariesLocked(null, Collections.unmodifiableMap(mPackages));
...
// 读取并更新要保留的package的上次使用时间
mPackageUsage.read(mPackages);
mCompilerStats.read();
}
}
}
}
阶段四：BOOT_PROGRESS_PMS_SCAN_END
主要工作：
- sdk版本变更，更新权限
- OTA升级后首次启动，清除不必要的缓存数据
- 权限等默认更新后，清理相关数据
- 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.
// 如果自上次启动以来，平台SDK已改变，则需要重新授予应用程序权限以捕获出现的任何新权限
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.
// 如果这是第一次启动或来自Android M之前的版本的升级，并且它是正常启动，那需要在所有已定义的用户中初始化默认的首选应用程序
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
// 在启动期间为系统用户准备存储，因为像SettingsProvider和SystemUI这样的核心系统应用程序无法等待用户启动
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之后首次启动，并且正常启动，那需要清除代码缓存目录，但不清除应用程序配置文件
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.
//安装Android-Q前的非系统应用程序在Launcher中隐藏他们的图标
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
// 仅在权限或其它默认配置更新后清除
mExistingSystemPackages.clear();
mPromoteSystemApps = false;
...
// All the changes are done during package scanning.
// 所有变更均在扫描过程中完成
ver.databaseVersion = Settings.CURRENT_DATABASE_VERSION;
// can downgrade to reader
//降级去读取
mSettings.writeLPr();
}
}
}
阶段五：BOOT_PROGRESS_PMS_READY
主要工作有：
- 创建PackageInstallerService对
- GC回收内存
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 持有默认的权限授予和角色管理，所以这是核心系统的一个关键部分。
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).
// 阅读并更新dex文件的用法
// 在PM init结束时执行此操作，以便所有程序包都已协调其数据目录
// 此时知道了包的代码路径，因此可以验证磁盘文件并构建内部缓存
// 使用文件预计很小，因此与其他活动（例如包扫描）相比，加载和验证它应该花费相当小的时间
final Map> 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.
// 打开应用之后，及时回收处理
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.
// 上面的初始扫描在持有mPackage锁的同时对installd进行了多次调用
mInstaller.setWarnIfHeld(mPackages);
...
}
DEX优化
检查是否需要去更新Packages并进行dex优化，如果没有OTA升级，没有大版本升级，没有清除dalvik虚拟机缓存，可以去更新packages。最终调用的是Installer的dexopt进行优化
PKMS.java#updatePackagesIfNeeded()
更新packages的优先级：core app> system app > other app,调用performDexOptUpgrade()进行系统更新
public void updatePackagesIfNeeded() {
//只有system或是root用户才有权限请求 package update
enforceSystemOrRoot("Only the system can request package update");
//(1)判断有没有进行OTA升级，我们需要在OTA后重新提取。
boolean causeUpgrade = isDeviceUpgrading();
//(2)是否是第一次启动或是系统大版本升级
boolean causeFirstBoot = isFirstBoot() || mIsPreNUpgrade;
// We need to re-extract after a pruned cache, as AoT-ed files will be out of date.
//(3)判断是否有清除过dalvik虚拟机的缓存
boolean causePrunedCache = VMRuntime.didPruneDalvikCache();
//(4)如果上面的三个都没有，那么就不进行任何操作
if (!causeUpgrade && !causeFirstBoot && !causePrunedCache) {
return;
}
List pkgs;
synchronized (mPackages) {
//(5)按照package的优先级进行排序，core app >system app > other app
pkgs = PackageManagerServiceUtils.getPackagesForDexopt(mPackages.values(), this);
}
final long startTime = System.nanoTime(); //记录开始时间
//进行dex优化，
final int[] stats = performDexOptUpgrade(pkgs, mIsPreNUpgrade /* showDialog */,
causeFirstBoot ? REASON_FIRST_BOOT : REASON_BOOT,
false /* bootComplete */);
...
}
PackageManagerService.java#performDexOptUpgrade()
判断是否需要对package进行更新，如果需要那么更新会按照优先级完成dex优化，最终调用Install的dexopt进行dex优化。
private int[] performDexOptUpgrade(List pkgs, boolean showDialog,
final int compilationReason, boolean bootComplete) {
...
//循环取出packages，进行优化
for (PackageParser.Package pkg : pkgs) {
numberOfPackagesVisited++;
boolean useProfileForDexopt = false;
//第一次启动或是ota升级之后并且是系统应用才会进行odex
if ((isFirstBoot() || isDeviceUpgrading()) && isSystemApp(pkg)) {
...
}
...
//最终是调用 mInstaller.dexopt 完成优化的，installd守护进程，installer安装器和Installd通信
int primaryDexOptStaus = performDexOptTraced(new DexoptOptions(
pkg.packageName,
pkgCompilationReason,
dexoptFlags));
switch (primaryDexOptStaus) {
case PackageDexOptimizer.DEX_OPT_PERFORMED:
numberOfPackagesOptimized++; //odex优化完成的应用
break;
case PackageDexOptimizer.DEX_OPT_SKIPPED:
numberOfPackagesSkipped++; //跳过的应用
break;
case PackageDexOptimizer.DEX_OPT_FAILED:
numberOfPackagesFailed++; //失败的应用
break;
default:
Log.e(TAG, "Unexpected dexopt return code " + primaryDexOptStaus);
break;
}
}
return new int[] { numberOfPackagesOptimized, numberOfPackagesSkipped,
numberOfPackagesFailed };
}
磁盘维护
磁盘维护最终调用的是vold进行的fstrim进行清理操作
PackageManagerService.java#performFstrimIfNeeded()
主要执行磁盘清理工作，释放磁盘空间
public void performFstrimIfNeeded() {
//只有system或是root用户才有权限请求fstrim
enforceSystemOrRoot("Only the system can request fstrim");
// Before everything else, see whether we need to fstrim.
//在其他事情之前，看看我们是否需要fstrim
try {
//获取StorageManager对象
IStorageManager sm = PackageHelper.getStorageManager();
if (sm != null) {
boolean doTrim = false;
//获取执行FTRIM间隔，默认是3天，可以通过setting provider更改这个时间
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; //如果超过了三天就进行磁盘清理
Slog.w(TAG, "No disk maintenance in " + timeSinceLast
+ "; running immediately");
}
}
if (doTrim) {
final boolean dexOptDialogShown;
synchronized (mPackages) {
dexOptDialogShown = mDexOptDialogShown;
}
//如果不是第一次启动，显示一个提示框
if (!isFirstBoot() && dexOptDialogShown) {
try {
ActivityManager.getService().showBootMessage(
mContext.getResources().getString(
R.string.android_upgrading_fstrim), true);
} catch (RemoteException e) {
}
}
// 这里的sm是 StorageManagerService，发送消息H_FSTRIM给handler，然后再向vold发送fstrim命
sm.runMaintenance();
}
} else {
Slog.e(TAG, "storageManager service unavailable!");
}
} catch (RemoteException e) {
// Can't happen; StorageManagerService is local
}
}
PKMS准备就绪
PackageManagerService.java#systemReady()
systemReady主要完成默认授权和更新package的信息，通知等待pms的一些组件。
public void systemReady() {
//只有system或是root用户才有权限 声称system已经ready
enforceSystemOrRoot("Only the system can claim the system is ready");
ContentObserver co = new ContentObserver(mHandler) {
...
};
co.onChange(true); //注册一个监听
...
synchronized (mPackages) {
ArrayList removed = new ArrayList<>();
for (int i=0; i 0) {
for (int r=0; r {
updatePartnerAppInFota();
}).start();
}
大概流程就是这样，完。