在分析代码之前，我们尽可能的想像一下，如果是我们来设计这个应用管理，那么它应该具有什么功能？是否是我们window下面的程序管理一样呢？我们首先分析一下它要实现的功能：
1. 程序的安装，我们都知道android的程序安装有很多个步骤，具可能的每个很小的功能也想到
- dex优化文件
- 解压apk包
- 解析AndroidMainfest .xml文件
2.程序的删除
- 把缓存文件删除
- 把解压的文件删除
- 把相关的intent等信息删除
3.信息的查询，这里的信息查询就是一个很广的定义了，应用的信息包括很多intent信息，权限，还有应用名称等信息，我们还是罗列一下
- Intent service provider receiver等信息保存
- 应用权限
- 应用名，图标，还有资源的目录：
这就是我们所能想到的，有一些功能不一定，但我们知道android PMS的功能一定比较我们想的多，而且也会比我们想像的要复杂。
我们还是通过源码的分析加深对PMS的理解，首先，我们知道android 里面系统级的服务都是可以跨进程的，所以PMS也是一定是用binder机制来实现的，而且我们都都知道系统的服务一般是开机就启动的，通常是在SystemServer.java文件里面初始化，看一下源码：
pm = PackageManagerService.main(context, installer,
factoryTest != SystemServer.FACTORY_TEST_OFF,
onlyCore);
boolean firstBoot = false;
try {
firstBoot = pm.isFirstBoot();
} catch (RemoteException e) {
}
这里只是简单的调用main方法，并没有看到所说的注册，接着看main方法:
public static final IPackageManager main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
PackageManagerService m = new PackageManagerService(context, installer,
factoryTest, onlyCore);
ServiceManager.addService("package", m);
return m;
}
终于看到addService注册服务的方法。
还有两个地方也调用了PM,简单看一下：
try {
pm.performBootDexOpt();
} catch (Throwable e) {
reportWtf("performing boot dexopt", e);
}
主要是dex应用apk
try {
pm.systemReady();
} catch (Throwable e) {
reportWtf("making Package Manager Service ready", e);
}
告诉系统已经准备好了。
我们再接着看一下PackageManagerService的构造函数，这里面有三个参数：Instanller就是安装类，factoryTest 是否是工厂模式，onlyCore值是false
由于这个函数比较长我们分几个部分来分析:
第一部分
mContext = context;
mFactoryTest = factoryTest;
mOnlyCore = onlyCore;
mNoDexOpt = "eng".equals(SystemProperties.get("ro.build.type"));
mMetrics = new DisplayMetrics();
mSettings = new Settings(context);
mVendorSettings = new VendorSettings();
mSettings.addSharedUserLPw("android.uid.system",
Process.SYSTEM_UID, ApplicationInfo.FLAG_SYSTEM);
mSettings.addSharedUserLPw("android.uid.phone", RADIO_UID, ApplicationInfo.FLAG_SYSTEM);
mSettings.addSharedUserLPw("android.uid.log", LOG_UID, ApplicationInfo.FLAG_SYSTEM);
mSettings.addSharedUserLPw("android.uid.nfc", NFC_UID, ApplicationInfo.FLAG_SYSTEM);
mSettings.addSharedUserLPw("android.uid.bluetooth", BLUETOOTH_UID, ApplicationInfo.FLAG_SYSTEM);
...............
初始化Settings类，Setting的作用是管理android 运行过程中的一些设置信息。
认识一下Setting addSharedUserLPw方法有三个参数 第一个是应用名的字符串，第二个是UID，android系统每个进程都有id号，第三 应用所属的用户组，所以addSharedUserLPw就是设置应用的进程id和所属的用户组
SharedUserSetting addSharedUserLPw(String name, int uid, int pkgFlags) {
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;
}
s = new SharedUserSetting(name, pkgFlags);
s.userId = uid;
if (addUserIdLPw(uid, s, name)) {
mSharedUsers.put(name, s);
return s;
}
return null;
}mSharedUsers就是一个根据应用名 保存SharedUser相关信息的hashMap，为什么要用HashMap来保存呢，应该是为了索引比较方便快捷的原因。先判断有没有添加，如果没有添加则先成SharedUserSetting对象，添加进去。
再看一下addUserIdLPw方法
private boolean addUserIdLPw(int uid, Object obj, Object name) {
if (uid > Process.LAST_APPLICATION_UID) {
return false;
}
if (uid >= Process.FIRST_APPLICATION_UID) {
...............
mUserIds.set(index, obj);
} else {
if (mOtherUserIds.get(uid) != null) {
PackageManagerService.reportSettingsProblem(Log.ERROR,
"Adding duplicate shared id: " + uid
+ " name=" + name);
return false;
}
mOtherUserIds.put(uid, obj);
}
return true;
}
主要是把uid保存到集合里面，如果是系统应用则添加到mOtherUserIds里面，否则添加到mUserIds里面。
SharedUserSetting类保存多个应用package的相关信息，里面还有一个PackageSignatures 因为共享id的前提是两个应用必须有
继承GrantedPermissions 说明共享Id应用具有相同的权限.
要理解这个方法的含义，我们先来理解一下，android 中多个应用程序可以运行在同一个进程里面如 camera和gallery，还有SystemUI(状态栏)是运行在system进程的。
为什么应用之间在sharedUserId呢 ？主要有两个原因：1.资源的共享，如果应用A 要想访问应用B的资源和上下文就可以通过共享Id使它们运行在同一个进程里面。
第二个：权限问题，例如：如果应用共享system进程，就可以有操作系统的权限。
我们再来看一下xml关于sharedUserId一般是怎么配置的？
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.systemui"
coreApp="true"
android:sharedUserId="android.uid.system"
android:process="system"
>
一般要指定给sharedUserId一个字符串名字。
不过从上面的函数的参数我们可以分析一下SharedUserSetting的数据结构：
1.sharedUderId名字 也就相当是进程名字。
2.UId linux 系统中每个进程都有一个整数与进程相对应也就是UID
3.package包名，多个应用要共享Id 因此必须保存一个package相关的信息。
我们接着回去PMS的构造函数的第二部分：
<span style="white-space:pre"> </span>mInstaller = installer;
..................
synchronized (mInstallLock) {
// writer
synchronized (mPackages) {
mHandlerThread.start();
mHandler = new PackageHandler(mHandlerThread.getLooper());
Watchdog.getInstance().addThread(mHandler, mHandlerThread.getName(),
WATCHDOG_TIMEOUT);
<span style="white-space:pre"> </span><span style="color:#ff0000;">//初始化应用路径 </span><span style="white-space:pre"> </span>
File dataDir = Environment.getDataDirectory();
mAppDataDir = new File(dataDir, "data");
mAppInstallDir = new File(dataDir, "app");
mAppLibInstallDir = new File(dataDir, "app-lib");
mAsecInternalPath = new File(dataDir, "app-asec").getPath();
mUserAppDataDir = new File(dataDir, "user");
mDrmAppPrivateInstallDir = new File(dataDir, "app-private");
<span style="white-space:pre"> </span> ................
<span style="color:#ff0000;">//读取权限</span>
readPermissions();
............
<span style="white-space:pre"> </span> //<span style="color:#ff0000;">保存已经dex文件路径</span>
final HashSet<String> alreadyDexOpted = new HashSet<String>();
/**
* Add everything in the in the boot class path to the
* list of process files because dexopt will have been run
* if necessary during zygote startup.
*/
String bootClassPath = System.getProperty("java.boot.class.path");
if (bootClassPath != null) {
String[] paths = splitString(bootClassPath, ':');
for (int i=0; i<paths.length; i++) {
alreadyDexOpted.add(paths[i]);
}
} else {
Slog.w(TAG, "No BOOTCLASSPATH found!");
}
boolean didDexOpt = false;
/**
* Ensure all external libraries have had dexopt run on them.
*/
if (mSharedLibraries.size() > 0) {
Iterator<SharedLibraryEntry> libs = mSharedLibraries.values().iterator();
while (libs.hasNext()) {
String lib = libs.next().path;
if (lib == null) {
continue;
}
try {<span style="color:#ff0000;">//是否需要dex,如果没有dex过的话，调用installer进行dex</span>
if (dalvik.system.DexFile.isDexOptNeeded(lib)) {
alreadyDexOpted.add(lib);
mInstaller.dexopt(lib, Process.SYSTEM_UID, true);
didDexOpt = true;
}
} catch (FileNotFoundException e) {
Slog.w(TAG, "Library not found: " + lib);
} catch (IOException e) {
Slog.w(TAG, "Cannot dexopt " + lib + "; is it an APK or JAR? "
+ e.getMessage());
}
}
}
<span style="white-space:pre"> </span><span style="color:#ff0000;">//查找 framework目录下面的 apk 文件和jar 文件进行dex</span>
File frameworkDir = new File(Environment.getRootDirectory(), "framework");
// Gross hack for now: we know this file doesn't contain any
// code, so don't dexopt it to avoid the resulting log spew.
alreadyDexOpted.add(frameworkDir.getPath() + "/framework-res.apk");
// Gross hack for now: we know this file is only part of
// the boot class path for art, so don't dexopt it to
// avoid the resulting log spew.
alreadyDexOpted.add(frameworkDir.getPath() + "/core-libart.jar");
/**
* And there are a number of commands implemented in Java, which
* we currently need to do the dexopt on so that they can be
* run from a non-root shell.
*/
String[] frameworkFiles = frameworkDir.list();
if (frameworkFiles != null) {
for (int i=0; i<frameworkFiles.length; i++) {
File libPath = new File(frameworkDir, frameworkFiles[i]);
String path = libPath.getPath();
// Skip the file if we alrady did it.
if (alreadyDexOpted.contains(path)) {
continue;
}
// Skip the file if it is not a type we want to dexopt.
if (!path.endsWith(".apk") && !path.endsWith(".jar")) {
continue;
}
try {
if (dalvik.system.DexFile.isDexOptNeeded(path)) {
mInstaller.dexopt(path, Process.SYSTEM_UID, true);
didDexOpt = true;
}
} catch (FileNotFoundException e) {
Slog.w(TAG, "Jar not found: " + path);
} catch (IOException e) {
Slog.w(TAG, "Exception reading jar: " + path, e);
}
}
}
<span style="white-space:pre"> </span><span style="color:#ff0000;">//如果刚才有dex过lib 就删除临时文件</span>
if (didDexOpt) {
File dalvikCacheDir = new File(dataDir, "dalvik-cache");
// If we had to do a dexopt of one of the previous
// things, then something on the system has changed.
// Consider this significant, and wipe away all other
// existing dexopt files to ensure we don't leave any
// dangling around.
String[] files = dalvikCacheDir.list();
if (files != null) {
for (int i=0; i<files.length; i++) {
String fn = files[i];
if (fn.startsWith("data@app@")
|| fn.startsWith("data@app-private@")) {
Slog.i(TAG, "Pruning dalvik file: " + fn);
(new File(dalvikCacheDir, fn)).delete();
}
}
}
}
<span style="white-space:pre"> </span><span style="color:#ff0000;">//注册文件监听，同时进行scan，这里比较重要</span>
// Find base frameworks (resource packages without code).
mFrameworkInstallObserver = new AppDirObserver(
frameworkDir.getPath(), OBSERVER_EVENTS, true, false);
mFrameworkInstallObserver.startWatching();
scanDirLI(frameworkDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED,
scanMode | SCAN_NO_DEX, 0);
// Collected privileged system packages.
File privilegedAppDir = new File(Environment.getRootDirectory(), "priv-app");
mPrivilegedInstallObserver = new AppDirObserver(
privilegedAppDir.getPath(), OBSERVER_EVENTS, true, true);
mPrivilegedInstallObserver.startWatching();
scanDirLI(privilegedAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED, scanMode, 0);
// Collect ordinary system packages.
File systemAppDir = new File(Environment.getRootDirectory(), "app");
mSystemInstallObserver = new AppDirObserver(
systemAppDir.getPath(), OBSERVER_EVENTS, true, false);
mSystemInstallObserver.startWatching();
<span style="color:#ff0000;">scanDirLI</span>(systemAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanMode, 0);
// Collect all vendor packages.
File vendorAppDir = new File("/vendor/app");
mVendorInstallObserver = new AppDirObserver(
vendorAppDir.getPath(), OBSERVER_EVENTS, true, false);
mVendorInstallObserver.startWatching();
<span style="color:#ff0000;">scanDirLI</span>(vendorAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanMode, 0);
if (DEBUG_UPGRADE) Log.v(TAG, "Running installd update commands");
mInstaller.moveFiles();
// Prune any system packages that no longer exist.
final List<String> possiblyDeletedUpdatedSystemApps = new ArrayList<String>();
if (!mOnlyCore) {
Iterator<PackageSetting> psit = mSettings.mPackages.values().iterator();
while (psit.hasNext()) {
PackageSetting ps = psit.next();
/*
* If this is not a system app, it can't be a
* disable system app.
*/
if ((ps.pkgFlags & ApplicationInfo.FLAG_SYSTEM) == 0) {
continue;
}
/*
* If the package is scanned, it's not erased.
*/
final PackageParser.Package scannedPkg = mPackages.get(ps.name);
if (scannedPkg != null) {
/*
* If the system app is both scanned and in the
* disabled packages list, then it must have been
* added via OTA. Remove it from the currently
* scanned package so the previously user-installed
* application can be scanned.
*/
if (mSettings.isDisabledSystemPackageLPr(ps.name)) {
Slog.i(TAG, "Expecting better updatd system app for " + ps.name
+ "; removing system app");
removePackageLI(ps, true);
}
continue;
}
if (!mSettings.isDisabledSystemPackageLPr(ps.name)) {
psit.remove();
String msg = "System package " + ps.name
+ " no longer exists; wiping its data";
reportSettingsProblem(Log.WARN, msg);
removeDataDirsLI(ps.name);
} else {
final PackageSetting disabledPs = mSettings.getDisabledSystemPkgLPr(ps.name);
if (disabledPs.codePath == null || !disabledPs.codePath.exists()) {
possiblyDeletedUpdatedSystemApps.add(ps.name);
}
}
}
}
//look for any incomplete package installations
ArrayList<PackageSetting> deletePkgsList = mSettings.getListOfIncompleteInstallPackagesLPr();
//clean up list
for(int i = 0; i < deletePkgsList.size(); i++) {
//clean up here
cleanupInstallFailedPackage(deletePkgsList.get(i));
}
//delete tmp files
<span style="color:#ff0000;">deleteTempPackageFiles</span>();
// Remove any shared userIDs that have no associated packages
mSettings.pruneSharedUsersLPw();
if (!mOnlyCore) {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
SystemClock.uptimeMillis());
mAppInstallObserver = new AppDirObserver(
mAppInstallDir.getPath(), OBSERVER_EVENTS, false, false);
mAppInstallObserver.startWatching();
scanDirLI(mAppInstallDir, 0, scanMode, 0);
mDrmAppInstallObserver = new AppDirObserver(
mDrmAppPrivateInstallDir.getPath(), OBSERVER_EVENTS, false, false);
mDrmAppInstallObserver.startWatching();
<span style="color:#ff0000;">scanDirLI</span>(mDrmAppPrivateInstallDir, PackageParser.PARSE_FORWARD_LOCK,
scanMode, 0);
/**
* Remove disable package settings for any updated system
* apps that were removed via an OTA. If they're not a
* previously-updated app, remove them completely.
* Otherwise, just revoke their system-level permissions.
*/
for (String deletedAppName : possiblyDeletedUpdatedSystemApps) {
PackageParser.Package deletedPkg = mPackages.get(deletedAppName);
mSettings.removeDisabledSystemPackageLPw(deletedAppName);
String msg;
if (deletedPkg == null) {
msg = "Updated system package " + deletedAppName
+ " no longer exists; wiping its data";
removeDataDirsLI(deletedAppName);
} else {
msg = "Updated system app + " + deletedAppName
+ " no longer present; removing system privileges for "
+ deletedAppName;
deletedPkg.applicationInfo.flags &= ~ApplicationInfo.FLAG_SYSTEM;
PackageSetting deletedPs = mSettings.mPackages.get(deletedAppName);
deletedPs.pkgFlags &= ~ApplicationInfo.FLAG_SYSTEM;
}
reportSettingsProblem(Log.WARN, msg);
}
} else {
mAppInstallObserver = null;
mDrmAppInstallObserver = null;
}
// Now that we know all of the shared libraries, update all clients to have
// the correct library paths.
<span style="color:#ff0000;">updateAllSharedLibrariesLPw</span>();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
Slog.i(TAG, "Time to scan packages: "
+ ((SystemClock.uptimeMillis()-startTime)/1000f)
+ " seconds");
// 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.
final boolean regrantPermissions = mSettings.mInternalSdkPlatform
!= mSdkVersion;
if (regrantPermissions) Slog.i(TAG, "Platform changed from "
+ mSettings.mInternalSdkPlatform + " to " + mSdkVersion
+ "; regranting permissions for internal storage");
mSettings.mInternalSdkPlatform = mSdkVersion;
<span style="color:#ff0000;">updatePermissionsLPw</span>(null, null, UPDATE_PERMISSIONS_ALL
| (regrantPermissions
? (UPDATE_PERMISSIONS_REPLACE_PKG|UPDATE_PERMISSIONS_REPLACE_ALL)
: 0));
// If this is the first boot, and it is a normal boot, then
// we need to initialize the default preferred apps.
if (!mRestoredSettings && !onlyCore) {
mSettings.readDefaultPreferredAppsLPw(this, 0);
}
// can downgrade to reader
<span style="color:#ff0000;">mSettings.writeLPr();</span>
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
// Now after opening every single application zip, make sure they
// are all flushed. Not really needed, but keeps things nice and
// tidy.
Runtime.getRuntime().gc();
mRequiredVerifierPackage = getRequiredVerifierLPr();
} // synchronized (mPackages)
} // synchronized (mInstallLock)
上面的代码看似很复杂，其实不复杂很多都是重复的。我们来归纳一下:
1.readPermissions 读取权限,读取system/etc/permissions/platform.xml文件。
2.dex 文件，dex各个路径下面的文件：SharedLibraries ,framework app等目录下面的文件进行dex.
3.注册文件监听，同时scan(解析)各个文件. 依次目录：framework priv-app app /vendor/app
4.做一些扫尾工作，删除临时文件，更新用户权限表，sharedUid等表。
看一下读取权限方法：
void readPermissions() {
// Read permissions from .../etc/permission directory.
File libraryDir = new File(Environment.getRootDirectory(), "etc/permissions");
if (!libraryDir.exists() || !libraryDir.isDirectory()) {
Slog.w(TAG, "No directory " + libraryDir + ", skipping");
return;
}
if (!libraryDir.canRead()) {
Slog.w(TAG, "Directory " + libraryDir + " cannot be read");
return;
}
// Iterate over the files in the directory and scan .xml files
for (File f : libraryDir.listFiles()) {
// We'll read platform.xml last
if (f.getPath().endsWith("etc/permissions/platform.xml")) {
continue;
}
if (!f.getPath().endsWith(".xml")) {
Slog.i(TAG, "Non-xml file " + f + " in " + libraryDir + " directory, ignoring");
continue;
}
if (!f.canRead()) {
Slog.w(TAG, "Permissions library file " + f + " cannot be read");
continue;
}
readPermissionsFromXml(f);
}
// Read permissions from .../etc/permissions/platform.xml last so it will take precedence
final File permFile = new File(Environment.getRootDirectory(),
"etc/permissions/platform.xml");
readPermissionsFromXml(permFile);
}
主要是遍历etc/permissions目录下面的文件查找platform.xml，然后调用readPermissionsFromXml进行解析。在看解析方法之前我们先看一下xml 的结构：
<permissions>
<!-- The following tags are associating low-level group IDs with
permission names. By specifying such a mapping, you are saying
that any application process granted the given permission will
also be running with the given group ID attached to its process,
so it can perform any filesystem (read, write, execute) operations
allowed for that group. -->
<permission name="android.permission.BLUETOOTH_ADMIN" >
<group gid="net_bt_admin" />
</permission>
<permission name="android.permission.BLUETOOTH" >
<group gid="net_bt" />
</permission>
<permission name="android.permission.BLUETOOTH_STACK" >
<group gid="net_bt_stack" />
</permission>
<span style="white-space:pre"> </span>.........
<!-- ================================================================== -->
<!-- ================================================================== -->
<!-- ================================================================== -->
<!-- The following tags are assigning high-level permissions to specific
user IDs. These are used to allow specific core system users to
perform the given operations with the higher-level framework. For
example, we give a wide variety of permissions to the shell user
since that is the user the adb shell runs under and developers and
others should have a fairly open environment in which to
interact with the system. -->
<assign-permission name="android.permission.MODIFY_AUDIO_SETTINGS" uid="media" />
<assign-permission name="android.permission.ACCESS_SURFACE_FLINGER" uid="media" />
<assign-permission name="android.permission.WAKE_LOCK" uid="media" />
<assign-permission name="android.permission.UPDATE_DEVICE_STATS" uid="media" />
<assign-permission name="android.permission.UPDATE_APP_OPS_STATS" uid="media" />
<assign-permission name="android.permission.ACCESS_SURFACE_FLINGER" uid="graphics" />
<!-- This is a list of all the libraries available for application
code to link against. -->
<library name="android.test.runner"
file="/system/framework/android.test.runner.jar" />
<library name="javax.obex"
file="/system/framework/javax.obex.jar"/>
</permissions> <permission name="android.permission.INTERNET" >
<group gid="inet" />
</permission>
将字符串的权限 也gid做对应起来，比如：你声明了android.permission.INTERNET 这个权限那就相当于你拥有用户组inet的所有权限.
<assign-permission name="android.permission.MODIFY_AUDIO_SETTINGS" uid="media" /> 将相关的权限与uid相对应起来。
<library name="android.test.runner"
file="/system/framework/android.test.runner.jar" /> 表示如果声明了android.test.runner权限就会自动加载相应的包.
再看一下readPermissionsFromXml方法：
while (true) {
XmlUtils.nextElement(parser);
if (parser.getEventType() == XmlPullParser.END_DOCUMENT) {
break;
}
String name = parser.getName();
if ("group".equals(name)) {
............
continue;
} else if ("permission".equals(name)) {
......
readPermission(parser, perm);
} else if ("assign-permission".equals(name)) {
.......
perm = perm.intern();
HashSet<String> perms = mSystemPermissions.get(uid);
if (perms == null) {
perms = new HashSet<String>();
mSystemPermissions.put(uid, perms);
}
perms.add(perm);
XmlUtils.skipCurrentTag(parser);
} else if ("library".equals(name)) {
String lname = parser.getAttributeValue(null, "name");
String lfile = parser.getAttributeValue(null, "file");
if (lname == null) {
Slog.w(TAG, "<library> without name at "
+ parser.getPositionDescription());
} else if (lfile == null) {
Slog.w(TAG, "<library> without file at "
+ parser.getPositionDescription());
} else {
//Log.i(TAG, "Got library " + lname + " in " + lfile);
mSharedLibraries.put(lname, new SharedLibraryEntry(lfile, null));
}
XmlUtils.skipCurrentTag(parser);
continue;
} else if ("feature".equals(name)) {
String fname = parser.getAttributeValue(null, "name");
if (fname == null) {
Slog.w(TAG, "<feature> without name at "
+ parser.getPositionDescription());
} else {
//Log.i(TAG, "Got feature " + fname);
FeatureInfo fi = new FeatureInfo();
fi.name = fname;
mAvailableFeatures.put(fname, fi);
}
XmlUtils.skipCurrentTag(parser);
continue;
} else {
XmlUtils.skipCurrentTag(parser);
continue;
}
}
如果遇到assign-permission ,则添加到mSystemPermissions 里面保存 key 值 为 uid
如果是 library ,则添加到mSharedLibraries HashMap中保存 key值为权限名
如果是feature 则添加到mAvailableFeatures HashMap中保存，key值name
如果是permission 情况却不一样，还要调用readPermission再解析：
void readPermission(XmlPullParser parser, String name)
throws IOException, XmlPullParserException {
name = name.intern();
BasePermission bp = mSettings.mPermissions.get(name);
if (bp == null) {
bp = new BasePermission(name, null, BasePermission.TYPE_BUILTIN);
mSettings.mPermissions.put(name, bp);
}
int outerDepth = parser.getDepth();
int type;
while ((type=parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG
|| parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG
|| type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if ("group".equals(tagName)) {
String gidStr = parser.getAttributeValue(null, "gid");
if (gidStr != null) {
int gid = Process.getGidForName(gidStr);
bp.gids = appendInt(bp.gids, gid);
} else {
Slog.w(TAG, "<group> without gid at "
+ parser.getPositionDescription());
}
}
XmlUtils.skipCurrentTag(parser);
}
}
这里出现了一新的变量mSettings.mPermissions 我们先来看一下它是什么东西来的？
mPermissions 是用来保存用户权限的，在PMS之前已经初始化，主要是通过解析system目录下面的packages.xml，如果是第一次开机是不会有这个文件。这里我们可以认为mPermissions里面的数据是空的。所以会生成新的BasePermission对象，再添加到mPermissions里面去，再解析读取gid 添加到
BasePermission对象里面的 gids。
到这里，readPermissions 读取权限的过程已经分析完成了。
接着看dex过程，整个过程相对比较简单,这里不再分析，其实它的功能都是通过 installer去实现，后面我们再分析installer的dex 过程。
分析一下AppDirObserver;这里监听app目录文件的添加，删除等操作，如果是有文件添加进里，发现没有解析过的文件就会调用扫描过程，同时会更新权限等操作，删除则是相反。
我们还是重点分析一下scanDirLI整个过程：
private void scanDirLI(File dir, int flags, int scanMode, long currentTime) {
String[] files = dir.list();
if (files == null) {
Log.d(TAG, "No files in app dir " + dir);
return;
}
if (DEBUG_PACKAGE_SCANNING) {
Log.d(TAG, "Scanning app dir " + dir + " scanMode=" + scanMode
+ " flags=0x" + Integer.toHexString(flags));
}
int i;
for (i=0; i<files.length; i++) {
File file = new File(dir, files[i]);
if (!isPackageFilename(files[i])) {
// Ignore entries which are not apk's
continue;
}
PackageParser.Package pkg = scanPackageLI(file,
flags|PackageParser.PARSE_MUST_BE_APK, scanMode, currentTime, null);
// Don't mess around with apps in system partition.
if (pkg == null && (flags & PackageParser.PARSE_IS_SYSTEM) == 0 &&
mLastScanError == PackageManager.INSTALL_FAILED_INVALID_APK) {
// Delete the apk
Slog.w(TAG, "Cleaning up failed install of " + file);
file.delete();
}
}
}
遍历目录下面的所有apk 文件调用scanPackageLI进行扫描:
private PackageParser.Package scanPackageLI(File scanFile,
int parseFlags, int scanMode, long currentTime, UserHandle user) {
..............// <span style="color:#ff0000;">解析器</span>
final PackageParser.Package pkg = pp.parsePackage(scanFile,
scanPath, mMetrics, parseFlags);
if (pkg == null) {
mLastScanError = pp.getParseError();
return null;
}
PackageSetting ps = null;
PackageSetting updatedPkg;
// reader
......./<span style="color:#ff6666;">/省略部分为应用升级处理部分. </span>
if (updatedPkg != null) {
// An updated system app will not have the PARSE_IS_SYSTEM flag set
// initially
parseFlags |= PackageParser.PARSE_IS_SYSTEM;
}
// Verify certificates against what was last scanned
if (!collectCertificatesLI(pp, ps, pkg, scanFile, parseFlags)) {
Slog.w(TAG, "Failed verifying certificates for package:" + pkg.packageName);
return null;
}
/*
* A new system app appeared, but we already had a non-system one of the
* same name installed earlier.
*/
boolean shouldHideSystemApp = false;
if (updatedPkg == null && ps != null
&& (parseFlags & PackageParser.PARSE_IS_SYSTEM_DIR) != 0 && !isSystemApp(ps)) {
/*
* Check to make sure the signatures match first. If they don't,
* wipe the installed application and its data.
*/
if (compareSignatures(ps.signatures.mSignatures, pkg.mSignatures)
!= PackageManager.SIGNATURE_MATCH) {
if (DEBUG_INSTALL) Slog.d(TAG, "Signature mismatch!");
deletePackageLI(pkg.packageName, null, true, null, null, 0, null, false);
ps = null;
} else {
/*
* If the newly-added system app is an older version than the
* already installed version, hide it. It will be scanned later
* and re-added like an update.
*/
if (pkg.mVersionCode < ps.versionCode) {
shouldHideSystemApp = true;
} else {
/*
* The newly found system app is a newer version that the
* one previously installed. Simply remove the
* already-installed application and replace it with our own
* while keeping the application data.
*/
Slog.w(TAG, "Package " + ps.name + " at " + scanFile + "reverting from "
+ ps.codePathString + ": new version " + pkg.mVersionCode
+ " better than installed " + ps.versionCode);
InstallArgs args = createInstallArgs(packageFlagsToInstallFlags(ps),
ps.codePathString, ps.resourcePathString, ps.nativeLibraryPathString);
synchronized (mInstallLock) {
args.cleanUpResourcesLI();
}
}
}
}
// The apk is forward locked (not public) if its code and resources
// are kept in different files. (except for app in either system or
// vendor path).
// TODO grab this value from PackageSettings
if ((parseFlags & PackageParser.PARSE_IS_SYSTEM_DIR) == 0) {
if (ps != null && !ps.codePath.equals(ps.resourcePath)) {
parseFlags |= PackageParser.PARSE_FORWARD_LOCK;
}
}
String codePath = null;
String resPath = null;
if ((parseFlags & PackageParser.PARSE_FORWARD_LOCK) != 0) {
if (ps != null && ps.resourcePathString != null) {
resPath = ps.resourcePathString;
} else {
// Should not happen at all. Just log an error.
Slog.e(TAG, "Resource path not set for pkg : " + pkg.packageName);
}
} else {
resPath = pkg.mScanPath;
}
codePath = pkg.mScanPath;
// Set application objects path explicitly.
setApplicationInfoPaths(pkg, codePath, resPath);
// Note that we invoke the following method only if we are about to unpack an application
PackageParser.Package scannedPkg = scanPackageLI(pkg, parseFlags, scanMode
| SCAN_UPDATE_SIGNATURE, currentTime, user);
/*
* If the system app should be overridden by a previously installed
* data, hide the system app now and let the /data/app scan pick it up
* again.
*/
if (shouldHideSystemApp) {
synchronized (mPackages) {
/*
* We have to grant systems permissions before we hide, because
* grantPermissions will assume the package update is trying to
* expand its permissions.
*/
grantPermissionsLPw(pkg, true);
mSettings.disableSystemPackageLPw(pkg.packageName);
}
}
return scannedPkg;
}
主要有三个部分构成：
1. 构造解析器，解析文件.
2. 应用升级部分的处理.
3. 构建应用的相关信息。
解析AndroidManifest文件
public Package parsePackage(File sourceFile, String destCodePath,
DisplayMetrics metrics, int flags) {
..............
XmlResourceParser parser = null;
AssetManager assmgr = null;
Resources res = null;
boolean assetError = true;
try {
assmgr = new AssetManager();
int cookie = assmgr.addAssetPath(mArchiveSourcePath);
if (cookie != 0) {
res = new Resources(assmgr, metrics, null);
assmgr.setConfiguration(0, 0, null, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
Build.VERSION.RESOURCES_SDK_INT);
parser = assmgr.openXmlResourceParser(cookie, ANDROID_MANIFEST_FILENAME);
assetError = false;
} else {
Slog.w(TAG, "Failed adding asset path:"+mArchiveSourcePath);
}
} catch (Exception e) {
Slog.w(TAG, "Unable to read AndroidManifest.xml of "
+ mArchiveSourcePath, e);
}
if (assetError) {
if (assmgr != null) assmgr.close();
mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_MANIFEST;
return null;
}
String[] errorText = new String[1];
Package pkg = null;
Exception errorException = null;
try {
// XXXX todo: need to figure out correct configuration.
pkg = parsePackage(res, parser, flags, errorText);
} catch (Exception e) {
errorException = e;
mParseError = PackageManager.INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION;
}
<span style="white-space:pre"> </span>................
return pkg;
}
使用AssetManager读取apk里面的AndroidManifest文件并进行解析，真正的解析过程是在parsePackage方法，这个方法比较长，不过代码不难读懂。
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals("application")) {
if (foundApp) {
if (RIGID_PARSER) {
outError[0] = "<manifest> has more than one <application>";
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return null;
} else {
Slog.w(TAG, "<manifest> has more than one <application>");
XmlUtils.skipCurrentTag(parser);
continue;
}
}
foundApp = true;
if (!parseApplication(pkg, res, parser, attrs, flags, outError)) {
return null;
}
} else if (tagName.equals("keys")) {
if (!parseKeys(pkg, res, parser, attrs, outError)) {
return null;
}
} else if (tagName.equals("permission-group")) {
if (parsePermissionGroup(pkg, flags, res, parser, attrs, outError) == null) {
return null;
}
} else if (tagName.equals("permission")) {
if (parsePermission(pkg, res, parser, attrs, outError) == null) {
return null;
}
} else if (tagName.equals("permission-tree")) {
if (parsePermissionTree(pkg, res, parser, attrs, outError) == null) {
return null;
}
} else if (tagName.equals("uses-permission")) {
if (!parseUsesPermission(pkg, res, parser, attrs, outError)) {
return null;
} ..................
这里只是解析一些配置项，如permission 等，我们重点看一下解析activity 等四大组件的相关信息parseApplication：
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > innerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals("activity")) {
Activity a = parseActivity(owner, res, parser, attrs, flags, outError, false,
hardwareAccelerated);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.activities.add(a);
} else if (tagName.equals("receiver")) {
Activity a = parseActivity(owner, res, parser, attrs, flags, outError, true, false);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.receivers.add(a);
}.................
return true;
}
主要是解析生成activity 对象 parseActivity(owner, res, parser, attrs, flags, outError, true, false) 这里的activity和系统里面四大组件的activtiy不是同一个。
这里有一张类图表示各个类的继承关系。parseActivity只是生成activity对象，并且对activity的属性进行赋值而已。其他三个组件的过程很相似这里就不再分析了，细心就会发现这些数据的父类都是IntentFilter ，为什么是IntentFilter呢？这里思考一下就可以猜到，为了方便查找，特别是activityManagerService调用 pms查询intent的信息的时候。
应用升级部分的处理
通过与保存在Settings里面的信息作一个对比，如果发现应用升级，就会进行安装，同时更新相关信息，这里不做分析 。。
构建完整的应用信息
再一次解析apk ，以此来构建系统中真正的应用，具体来看一下scanPackageLI方法;这个方法也是比较长的，不过总结来说不是很难分析，只是有耐心去看就可以了。
第一：如果是系统的apk（frameworkd-res.apk）就会做一些特殊的处理;
if (pkg.packageName.equals("android")) {
synchronized (mPackages) {
if (mAndroidApplication != null) {
Slog.w(TAG, "*************************************************");
Slog.w(TAG, "Core android package being redefined. Skipping.");
Slog.w(TAG, " file=" + mScanningPath);
Slog.w(TAG, "*************************************************");
mLastScanError = PackageManager.INSTALL_FAILED_DUPLICATE_PACKAGE;
return null;
}
// Set up information for our fall-back user intent resolution activity.
mPlatformPackage = pkg;
pkg.mVersionCode = mSdkVersion;
mAndroidApplication = pkg.applicationInfo;
if (!mResolverReplaced) {
mResolveActivity.applicationInfo = mAndroidApplication;
mResolveActivity.name = ResolverActivity.class.getName();
mResolveActivity.packageName = mAndroidApplication.packageName;
mResolveActivity.processName = "system:ui";
mResolveActivity.launchMode = ActivityInfo.LAUNCH_MULTIPLE;
mResolveActivity.flags = ActivityInfo.FLAG_EXCLUDE_FROM_RECENTS;
mResolveActivity.theme = com.android.internal.R.style.Theme_Holo_Dialog_Alert;
mResolveActivity.exported = true;
mResolveActivity.enabled = true;
mResolveInfo.activityInfo = mResolveActivity;
mResolveInfo.priority = 0;
mResolveInfo.preferredOrder = 0;
mResolveInfo.match = 0;
mResolveComponentName = new ComponentName(
mAndroidApplication.packageName, mResolveActivity.name);
}
}
}主要处理共用并且常用的activity 如：ChooserActivity 和ShutdownActivity
第二部分：主要处理uses-lib和sharedUid 以及verifySignatures 这里比较简单不做分析。
第三部分：创建data/data/应用名目录
final String pkgName = pkg.packageName;
final long scanFileTime = scanFile.lastModified();
final boolean forceDex = (scanMode&SCAN_FORCE_DEX) != 0;
pkg.applicationInfo.processName = fixProcessName(
pkg.applicationInfo.packageName,
pkg.applicationInfo.processName,
pkg.applicationInfo.uid);
File dataPath;
if (mPlatformPackage == pkg) {
// The system package is special.
dataPath = new File (Environment.getDataDirectory(), "system");
pkg.applicationInfo.dataDir = dataPath.getPath();
} else {
// This is a normal package, need to make its data directory.
dataPath = getDataPathForPackage(pkg.packageName, 0);
boolean uidError = false;
if (dataPath.exists()) {
int currentUid = 0;
try {
StructStat stat = Libcore.os.stat(dataPath.getPath());
currentUid = stat.st_uid;
} catch (ErrnoException e) {
Slog.e(TAG, "Couldn't stat path " + dataPath.getPath(), e);
}
// If we have mismatched owners for the data path, we have a problem.
if (currentUid != pkg.applicationInfo.uid) {
boolean recovered = false;
if (currentUid == 0) {
// The directory somehow became owned by root. Wow.
// This is probably because the system was stopped while
// installd was in the middle of messing with its libs
// directory. Ask installd to fix that.
int ret = mInstaller.fixUid(pkgName, pkg.applicationInfo.uid,
pkg.applicationInfo.uid);
if (ret >= 0) {
recovered = true;
String msg = "Package " + pkg.packageName
+ " unexpectedly changed to uid 0; recovered to " +
+ pkg.applicationInfo.uid;
reportSettingsProblem(Log.WARN, msg);
}
}
if (!recovered && ((parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0
|| (scanMode&SCAN_BOOTING) != 0)) {
// If this is a system app, we can at least delete its
// current data so the application will still work.
int ret = removeDataDirsLI(pkgName);
if (ret >= 0) {
// TODO: Kill the processes first
// Old data gone!
String prefix = (parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0
? "System package " : "Third party package ";
String msg = prefix + pkg.packageName
+ " has changed from uid: "
+ currentUid + " to "
+ pkg.applicationInfo.uid + "; old data erased";
reportSettingsProblem(Log.WARN, msg);
recovered = true;
// And now re-install the app.
ret = createDataDirsLI(pkgName, pkg.applicationInfo.uid,
pkg.applicationInfo.seinfo);
if (ret == -1) {
// Ack should not happen!
msg = prefix + pkg.packageName
+ " could not have data directory re-created after delete.";
reportSettingsProblem(Log.WARN, msg);
mLastScanError = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
return null;
}
}
if (!recovered) {
mHasSystemUidErrors = true;
}
} else if (!recovered) {
// If we allow this install to proceed, we will be broken.
// Abort, abort!
mLastScanError = PackageManager.INSTALL_FAILED_UID_CHANGED;
return null;
}
if (!recovered) {
pkg.applicationInfo.dataDir = "/mismatched_uid/settings_"
+ pkg.applicationInfo.uid + "/fs_"
+ currentUid;
pkg.applicationInfo.nativeLibraryDir = pkg.applicationInfo.dataDir;
String msg = "Package " + pkg.packageName
+ " has mismatched uid: "
+ currentUid + " on disk, "
+ pkg.applicationInfo.uid + " in settings";
// writer
synchronized (mPackages) {
mSettings.mReadMessages.append(msg);
mSettings.mReadMessages.append('\n');
uidError = true;
if (!pkgSetting.uidError) {
reportSettingsProblem(Log.ERROR, msg);
}
}
}
}
pkg.applicationInfo.dataDir = dataPath.getPath();
} else {
if (DEBUG_PACKAGE_SCANNING) {
if ((parseFlags & PackageParser.PARSE_CHATTY) != 0)
Log.v(TAG, "Want this data dir: " + dataPath);
}
//invoke installer to do the actual installation
int ret = createDataDirsLI(pkgName, pkg.applicationInfo.uid,
pkg.applicationInfo.seinfo);
if (ret < 0) {
// Error from installer
mLastScanError = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
return null;
}
if (dataPath.exists()) {
pkg.applicationInfo.dataDir = dataPath.getPath();
} else {
Slog.w(TAG, "Unable to create data directory: " + dataPath);
pkg.applicationInfo.dataDir = null;
}
}
第四，动态库的相关操作，复制，解压动态库，建立链接。
if (pkg.applicationInfo.nativeLibraryDir != null) {
try {
File nativeLibraryDir = new File(pkg.applicationInfo.nativeLibraryDir);
final String dataPathString = dataPath.getCanonicalPath();
if (isSystemApp(pkg) && !isUpdatedSystemApp(pkg)) {
/*
* Upgrading from a previous version of the OS sometimes
* leaves native libraries in the /data/data/<app>/lib
* directory for system apps even when they shouldn't be.
* Recent changes in the JNI library search path
* necessitates we remove those to match previous behavior.
*/
if (NativeLibraryHelper.removeNativeBinariesFromDirLI(nativeLibraryDir)) {
Log.i(TAG, "removed obsolete native libraries for system package "
+ path);
}
} else {
if (!isForwardLocked(pkg) && !isExternal(pkg)) {
/*
* Update native library dir if it starts with
* /data/data
*/
if (nativeLibraryDir.getPath().startsWith(dataPathString)) {
setInternalAppNativeLibraryPath(pkg, pkgSetting);
nativeLibraryDir = new File(pkg.applicationInfo.nativeLibraryDir);
}
try {
if (copyNativeLibrariesForInternalApp(scanFile, nativeLibraryDir) != PackageManager.INSTALL_SUCCEEDED) {
Slog.e(TAG, "Unable to copy native libraries");
mLastScanError = PackageManager.INSTALL_FAILED_INTERNAL_ERROR;
return null;
}
} catch (IOException e) {
Slog.e(TAG, "Unable to copy native libraries", e);
mLastScanError = PackageManager.INSTALL_FAILED_INTERNAL_ERROR;
return null;
}
}
if (DEBUG_INSTALL) Slog.i(TAG, "Linking native library dir for " + path);
final int[] userIds = sUserManager.getUserIds();
synchronized (mInstallLock) {
for (int userId : userIds) {
if (mInstaller.linkNativeLibraryDirectory(pkg.packageName,
pkg.applicationInfo.nativeLibraryDir, userId) < 0) {
Slog.w(TAG, "Failed linking native library dir (user=" + userId
+ ")");
mLastScanError = PackageManager.INSTALL_FAILED_INTERNAL_ERROR;
return null;
}
}
}
}
} catch (IOException ioe) {
Slog.e(TAG, "Unable to get canonical file " + ioe.toString());
}
}..................第五. 把四大组件相关信息复制到pms中
.....................
int N = pkg.providers.size();
StringBuilder r = null;
int i;
for (i=0; i<N; i++) {
PackageParser.Provider p = pkg.providers.get(i);
p.info.processName = fixProcessName(pkg.applicationInfo.processName,
p.info.processName, pkg.applicationInfo.uid);
mProviders.addProvider(p);
p.syncable = p.info.isSyncable;
if (p.info.authority != null) {
String names[] = p.info.authority.split(";");
p.info.authority = null;
for (int j = 0; j < names.length; j++) {
if (j == 1 && p.syncable) {
// We only want the first authority for a provider to possibly be
// syncable, so if we already added this provider using a different
// authority clear the syncable flag. We copy the provider before
// changing it because the mProviders object contains a reference
// to a provider that we don't want to change.
// Only do this for the second authority since the resulting provider
// object can be the same for all future authorities for this provider.
p = new PackageParser.Provider(p);
p.syncable = false;
}
if (!mProvidersByAuthority.containsKey(names[j])) {
mProvidersByAuthority.put(names[j], p);
if (p.info.authority == null) {
p.info.authority = names[j];
} else {
p.info.authority = p.info.authority + ";" + names[j];
}
if (DEBUG_PACKAGE_SCANNING) {
if ((parseFlags & PackageParser.PARSE_CHATTY) != 0)
Log.d(TAG, "Registered content provider: " + names[j]
+ ", className = " + p.info.name + ", isSyncable = "
+ p.info.isSyncable);
}
} else {
PackageParser.Provider other = mProvidersByAuthority.get(names[j]);
Slog.w(TAG, "Skipping provider name " + names[j] +
" (in package " + pkg.applicationInfo.packageName +
"): name already used by "
+ ((other != null && other.getComponentName() != null)
? other.getComponentName().getPackageName() : "?"));
}
}
}
if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
if (r == null) {
r = new StringBuilder(256);
} else {
r.append(' ');
}
r.append(p.info.name);
}
}
if (r != null) {
if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, " Providers: " + r);
}
............................
到这里总算分析完整个扫描过程，我们先来总结一下：整个扫描的过程都是构建Package 类，从开始的解析xml 文件，到后来的安装，还有信息的转换。都离不开Package类，这里也有大量的对象创建和赋值的过程。
再次回到pms的构造函数里面去，我们上面只是讲解了app目录下面的apk的扫描安装过程，还有几他几个目录也是一样的过程，这里不再分析。
最后，pms还有一些收尾的工作，具体来看一下：
<span style="white-space:pre"> </span>updateAllSharedLibrariesLPw();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
Slog.i(TAG, "Time to scan packages: "
+ ((SystemClock.uptimeMillis()-startTime)/1000f)
+ " seconds");
// 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.
final boolean regrantPermissions = mSettings.mInternalSdkPlatform
!= mSdkVersion;
if (regrantPermissions) Slog.i(TAG, "Platform changed from "
+ mSettings.mInternalSdkPlatform + " to " + mSdkVersion
+ "; regranting permissions for internal storage");
mSettings.mInternalSdkPlatform = mSdkVersion;
updatePermissionsLPw(null, null, UPDATE_PERMISSIONS_ALL
| (regrantPermissions
? (UPDATE_PERMISSIONS_REPLACE_PKG|UPDATE_PERMISSIONS_REPLACE_ALL)
: 0));
// If this is the first boot, and it is a normal boot, then
// we need to initialize the default preferred apps.
if (!mRestoredSettings && !onlyCore) {
mSettings.readDefaultPreferredAppsLPw(this, 0);
}
// can downgrade to reader
mSettings.writeLPr();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
// Now after opening every single application zip, make sure they
// are all flushed. Not really needed, but keeps things nice and
// tidy.
Runtime.getRuntime().gc();更新共享库：updateAllSharedLibrariesLPw
更新权限:updatePermissionsLPw
把相关信息保存：mSettings.writeLPr() 主要 package.xml package.list 等文件。
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