Android 1.6 PackageManagerService源码分析

文件清单

framework\base\services\core\java\com\android\server\pm\PackageManagerService.java

 

PackageManagerService.rar （已经带有文字注释的文件）

 

下面截取部分介绍

 

1 PMS初始化

    public static final IPackageManager main(Context context, boolean factoryTest) {
        PackageManagerService m = new PackageManagerService(context, factoryTest);
        ServiceManager.addService("package", m);
        return m;
    }

 

2 构造函数

public PackageManagerService(Context context, boolean factoryTest) {
        EventLog.writeEvent(LOG_BOOT_PROGRESS_PMS_START,
                SystemClock.uptimeMillis());
        
        if (mSdkVersion <= 0) {
            Log.w(TAG, "**** ro.build.version.sdk not set!");
        }
        
        mContext = context;
        mFactoryTest = factoryTest;
        mNoDexOpt = "eng".equals(SystemProperties.get("ro.build.type"));
        mMetrics = new DisplayMetrics();
        mSettings = new Settings();
        mSettings.addSharedUserLP("android.uid.system",
                Process.SYSTEM_UID, ApplicationInfo.FLAG_SYSTEM);
        mSettings.addSharedUserLP("android.uid.phone",
                MULTIPLE_APPLICATION_UIDS
                        ? RADIO_UID : FIRST_APPLICATION_UID,
                ApplicationInfo.FLAG_SYSTEM);

        String separateProcesses = SystemProperties.get("debug.separate_processes");
        if (separateProcesses != null && separateProcesses.length() > 0) {
            if ("*".equals(separateProcesses)) {
                mDefParseFlags = PackageParser.PARSE_IGNORE_PROCESSES;
                mSeparateProcesses = null;
                Log.w(TAG, "Running with debug.separate_processes: * (ALL)");
            } else {
                mDefParseFlags = 0;
                mSeparateProcesses = separateProcesses.split(",");
                Log.w(TAG, "Running with debug.separate_processes: "
                        + separateProcesses);
            }
        } else {
            mDefParseFlags = 0;
            mSeparateProcesses = null;
        }
        
        Installer installer = new Installer();
        // Little hacky thing to check if installd is here, to determine
        // whether we are running on the simulator and thus need to take
        // care of building the /data file structure ourself.
        // (apparently the sim now has a working installer)
        if (installer.ping() && Process.supportsProcesses()) {
            mInstaller = installer;
        } else {
            mInstaller = null;
        }

        WindowManager wm = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
        Display d = wm.getDefaultDisplay();
        d.getMetrics(mMetrics);

        synchronized (mInstallLock) {
        synchronized (mPackages) {
            mHandlerThread.start();
            mHandler = new Handler(mHandlerThread.getLooper());
            
            // data目录
            File dataDir = Environment.getDataDirectory();
            // 目录：data/data
            mAppDataDir = new File(dataDir, "data");
            // 目录：data/app-private
            mDrmAppPrivateInstallDir = new File(dataDir, "app-private");

            if (mInstaller == null) {
                // Make sure these dirs exist, when we are running in
                // the simulator.
                // Make a wide-open directory for random misc stuff.
                File miscDir = new File(dataDir, "misc");
                miscDir.mkdirs();
                mAppDataDir.mkdirs();
                mDrmAppPrivateInstallDir.mkdirs();
            }

            // 读：system/etc/permissions/platform.xml 等xml文件
            readPermissions();

            mRestoredSettings = mSettings.readLP();
            long startTime = SystemClock.uptimeMillis();
            
            EventLog.writeEvent(LOG_BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
                    startTime);
            
            int scanMode = SCAN_MONITOR;
            if (mNoDexOpt) {
                Log.w(TAG, "Running ENG build: no pre-dexopt!");
                scanMode |= SCAN_NO_DEX; 
            }
            
            final HashSet<String> libFiles = new HashSet<String>();
            
            // 目录：system/framework
            mFrameworkDir = new File(Environment.getRootDirectory(), "framework");
            
            if (mInstaller != null) {
                /**
                 * Out of paranoia, ensure that everything in the boot class
                 * path has been dexed.
                 */
                String bootClassPath = System.getProperty("java.boot.class.path");
                if (bootClassPath != null) {
                    String[] paths = splitString(bootClassPath, ':');
                    for (int i=0; i<paths.length; i++) {
                        try {
                            if (dalvik.system.DexFile.isDexOptNeeded(paths[i])) {
                                libFiles.add(paths[i]);
                                // 执行 dexopt 命令
                                mInstaller.dexopt(paths[i], Process.SYSTEM_UID, true);
                            }
                        } catch (FileNotFoundException e) {
                            Log.w(TAG, "Boot class path not found: " + paths[i]);
                        } catch (IOException e) {
                            Log.w(TAG, "Exception reading boot class path: " + paths[i], e);
                        }
                    }
                } else {
                    Log.w(TAG, "No BOOTCLASSPATH found!");
                }
                
                /**
                 * Also ensure all external libraries have had dexopt run on them.
                 */
                if (mSharedLibraries.size() > 0) {
                    Iterator<String> libs = mSharedLibraries.values().iterator();
                    while (libs.hasNext()) {
                        String lib = libs.next();
                        try {
                            if (dalvik.system.DexFile.isDexOptNeeded(lib)) {
                                libFiles.add(lib);
                                // 执行 dexopt 命令
                                mInstaller.dexopt(lib, Process.SYSTEM_UID, true);
                            }
                        } catch (FileNotFoundException e) {
                            Log.w(TAG, "Library not found: " + lib);
                        } catch (IOException e) {
                            Log.w(TAG, "Exception reading library: " + lib, e);
                        }
                    }
                }
                
                // 目录：system/framework/framework-res.apk
                // Gross hack for now: we know this file doesn't contain any
                // code, so don't dexopt it to avoid the resulting log spew.
                libFiles.add(mFrameworkDir.getPath() + "/framework-res.apk");
                
                /**
                 * 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 = mFrameworkDir.list(); // 列出 framework目录下所有文件
                if (frameworkFiles != null && mInstaller != null) {
                    for (int i=0; i<frameworkFiles.length; i++) {
                        File libPath = new File(mFrameworkDir, frameworkFiles[i]);
                        String path = libPath.getPath();
                        // Skip the file if we alrady did it.
                        if (libFiles.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)) {
                                // 执行 dexopt命令 apk & jar
                                mInstaller.dexopt(path, Process.SYSTEM_UID, true);
                            }
                        } catch (FileNotFoundException e) {
                            Log.w(TAG, "Jar not found: " + path);
                        } catch (IOException e) {
                            Log.w(TAG, "Exception reading jar: " + path, e);
                        }
                    }
                }
            }
            
            mFrameworkInstallObserver = new AppDirObserver(
                mFrameworkDir.getPath(), OBSERVER_EVENTS, true);
            mFrameworkInstallObserver.startWatching();
            // 扫描 system/framework 目录
            scanDirLI(mFrameworkDir, PackageParser.PARSE_IS_SYSTEM,
                    scanMode | SCAN_NO_DEX);
            mSystemAppDir = new File(Environment.getRootDirectory(), "app");
            mSystemInstallObserver = new AppDirObserver(
                mSystemAppDir.getPath(), OBSERVER_EVENTS, true);
            mSystemInstallObserver.startWatching();
            // 扫描 system/app 目录
            scanDirLI(mSystemAppDir, PackageParser.PARSE_IS_SYSTEM, scanMode);
            // data/app 目录
            mAppInstallDir = new File(dataDir, "app");
            if (mInstaller == null) {
                // Make sure these dirs exist, when we are running in
                // the simulator.
                mAppInstallDir.mkdirs(); // scanDirLI() assumes this dir exists // 创建 data/app目录
            }
            // 搜索未安装完成的程序包
            //look for any incomplete package installations
            ArrayList<String> deletePkgsList = mSettings.getListOfIncompleteInstallPackages();
            //clean up list
            for(int i = 0; i < deletePkgsList.size(); i++) {
                //clean up here
                cleanupInstallFailedPackage(deletePkgsList.get(i)); // 清理安装失败的包
            }
            //delete tmp files
            deleteTempPackageFiles();
            
            EventLog.writeEvent(LOG_BOOT_PROGRESS_PMS_DATA_SCAN_START,
                    SystemClock.uptimeMillis());
            mAppInstallObserver = new AppDirObserver(
                mAppInstallDir.getPath(), OBSERVER_EVENTS, false);
            mAppInstallObserver.startWatching();
            // 扫描 data/app 目录
            scanDirLI(mAppInstallDir, 0, scanMode);

            mDrmAppInstallObserver = new AppDirObserver(
                mDrmAppPrivateInstallDir.getPath(), OBSERVER_EVENTS, false);
            mDrmAppInstallObserver.startWatching();
            // 扫描 data/app-private 目录
            scanDirLI(mDrmAppPrivateInstallDir, 0, scanMode | SCAN_FORWARD_LOCKED);

            EventLog.writeEvent(LOG_BOOT_PROGRESS_PMS_SCAN_END,
                    SystemClock.uptimeMillis());
            Log.i(TAG, "Time to scan packages: "
                    + ((SystemClock.uptimeMillis()-startTime)/1000f)
                    + " seconds");

            updatePermissionsLP();

            // 初始化后
            mSettings.writeLP();

            EventLog.writeEvent(LOG_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();
        } // synchronized (mPackages)
        } // synchronized (mInstallLock)
    }

 

2.1 readPermissions()

void readPermissions() {
        // Read permissions from .../etc/permission directory.
        File libraryDir = new File(Environment.getRootDirectory(), "etc/permissions");
        if (!libraryDir.exists() || !libraryDir.isDirectory()) {
            Log.w(TAG, "No directory " + libraryDir + ", skipping");
            return;
        }
        if (!libraryDir.canRead()) {
            Log.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")) {
                Log.i(TAG, "Non-xml file " + f + " in " + libraryDir + " directory, ignoring");
                continue;
            }
            if (!f.canRead()) {
                Log.w(TAG, "Permissions library file " + f + " cannot be read");
                continue;
            }

            readPermissionsFromXml(f);
        }
        
        // 目录：system/etc/permissions/platform.xml
        // 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);
    }

 

 

2.1.1 readPermissionsFromXml

 private void readPermissionsFromXml(File permFile) {        
        FileReader permReader = null;
        try {
            permReader = new FileReader(permFile);
        } catch (FileNotFoundException e) {
            Log.w(TAG, "Couldn't find or open permissions file " + permFile);
            return;
        }

        try {
            XmlPullParser parser = Xml.newPullParser();
            parser.setInput(permReader);

            XmlUtils.beginDocument(parser, "permissions");

            while (true) {
                XmlUtils.nextElement(parser);
                if (parser.getEventType() == XmlPullParser.END_DOCUMENT) {
                    break;
                }

                String name = parser.getName();
                if ("group".equals(name)) {
                    String gidStr = parser.getAttributeValue(null, "gid");
                    if (gidStr != null) {
                        int gid = Integer.parseInt(gidStr);
                        mGlobalGids = appendInt(mGlobalGids, gid);
                    } else {
                        Log.w(TAG, "<group> without gid at "
                                + parser.getPositionDescription());
                    }

                    XmlUtils.skipCurrentTag(parser);
                    continue;
                } else if ("permission".equals(name)) {
                    String perm = parser.getAttributeValue(null, "name");
                    if (perm == null) {
                        Log.w(TAG, "<permission> without name at "
                                + parser.getPositionDescription());
                        XmlUtils.skipCurrentTag(parser);
                        continue;
                    }
                    perm = perm.intern();
                    readPermission(parser, perm);
                    
                } else if ("assign-permission".equals(name)) {
                    String perm = parser.getAttributeValue(null, "name");
                    if (perm == null) {
                        Log.w(TAG, "<assign-permission> without name at "
                                + parser.getPositionDescription());
                        XmlUtils.skipCurrentTag(parser);
                        continue;
                    }
                    String uidStr = parser.getAttributeValue(null, "uid");
                    if (uidStr == null) {
                        Log.w(TAG, "<assign-permission> without uid at "
                                + parser.getPositionDescription());
                        XmlUtils.skipCurrentTag(parser);
                        continue;
                    }
                    int uid = Process.getUidForName(uidStr);
                    if (uid < 0) {
                        Log.w(TAG, "<assign-permission> with unknown uid \""
                                + uidStr + "\" at "
                                + parser.getPositionDescription());
                        XmlUtils.skipCurrentTag(parser);
                        continue;
                    }
                    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) {
                        Log.w(TAG, "<library> without name at "
                                + parser.getPositionDescription());
                    } else if (lfile == null) {
                        Log.w(TAG, "<library> without file at "
                                + parser.getPositionDescription());
                    } else {
                        Log.i(TAG, "Got library " + lname + " in " + lfile);
                        this.mSharedLibraries.put(lname, lfile);
                    }
                    XmlUtils.skipCurrentTag(parser);
                    continue;
                    
                } else {
                    XmlUtils.skipCurrentTag(parser);
                    continue;
                }

            }
        } catch (XmlPullParserException e) {
            Log.w(TAG, "Got execption parsing permissions.", e);
        } catch (IOException e) {
            Log.w(TAG, "Got execption parsing permissions.", e);
        }
    }

 

2.2 mSettings.readLP()

boolean readLP() {
            FileInputStream str = null;
            // 如果 data/system/packages-backup.xml 文件存在，则继续
            if (mBackupSettingsFilename.exists()) {
                try {
                    //文件：data/system/packages-backup.xml
                    str = new FileInputStream(mBackupSettingsFilename);
                    mReadMessages.append("Reading from backup settings file\n");
                    Log.i(TAG, "Reading from backup settings file!");
                } catch (java.io.IOException e) {
                    // We'll try for the normal settings file.
                }
            }

            // 清除 mPastSignatures 列表
            mPastSignatures.clear();

            try {
                // 如果 "data/system/packages-backup.xml" 文件不存在
                if (str == null) {
                    // 如果 data/system/packages.xml 也不存在
                    if (!mSettingsFilename.exists()) {
                        mReadMessages.append("No settings file found\n");
                        Log.i(TAG, "No current settings file!");
                        return false; // 直接返回了
                    }
                    // 如果存在，则创建 data/system/packages.xml 文件流
                    str = new FileInputStream(mSettingsFilename);
                }
                //若packages-backup.xml存在，则解析，否则 解析 packages.xml 文件
                XmlPullParser parser = Xml.newPullParser();
                parser.setInput(str, null);

                int type;
                while ((type=parser.next()) != XmlPullParser.START_TAG
                           && type != XmlPullParser.END_DOCUMENT) {
                    ;
                }

                if (type != XmlPullParser.START_TAG) {
                    mReadMessages.append("No start tag found in settings file\n");
                    Log.e(TAG, "No start tag found in package manager settings");
                    return false;
                }

                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;
                    }

                    String tagName = parser.getName();
                    // 解析 packages.xml 文件中的 "package"
                    if (tagName.equals("package")) {
                        readPackageLP(parser); //解析 package 标签
                    } else if (tagName.equals("permissions")) { //解析 permissions 标签 
                        readPermissionsLP(mPermissions, parser);
                    } else if (tagName.equals("permission-trees")) {
                        readPermissionsLP(mPermissionTrees, parser);
                    } else if (tagName.equals("shared-user")) { // 解析 shared-user 标签
                        readSharedUserLP(parser);
                    } else if (tagName.equals("preferred-packages")) {
                        readPreferredPackagesLP(parser);
                    } else if (tagName.equals("preferred-activities")) {
                        readPreferredActivitiesLP(parser);
                    } else if(tagName.equals("updated-package")) { //解析 updated-package 标签
                        readDisabledSysPackageLP(parser);
                    } else {
                        Log.w(TAG, "Unknown element under <packages>: "
                              + parser.getName());
                        XmlUtils.skipCurrentTag(parser);
                    }
                }

                str.close();

            } catch(XmlPullParserException e) {
                mReadMessages.append("Error reading: " + e.toString());
                Log.e(TAG, "Error reading package manager settings", e);

            } catch(java.io.IOException e) {
                mReadMessages.append("Error reading: " + e.toString());
                Log.e(TAG, "Error reading package manager settings", e);

            }

            int N = mPendingPackages.size();
            for (int i=0; i<N; i++) {
                final PendingPackage pp = mPendingPackages.get(i);
                Object idObj = getUserIdLP(pp.sharedId);
                if (idObj != null && idObj instanceof SharedUserSetting) {
                    PackageSetting p = getPackageLP(pp.name,
                            (SharedUserSetting)idObj, pp.codePath, pp.resourcePath,
                            pp.versionCode, pp.pkgFlags, true, true);
                    if (p == null) {
                        Log.w(TAG, "Unable to create application package for "
                                + pp.name);
                        continue;
                    }
                    p.copyFrom(pp);
                } else if (idObj != null) {
                    String msg = "Bad package setting: package " + pp.name
                            + " has shared uid " + pp.sharedId
                            + " that is not a shared uid\n";
                    mReadMessages.append(msg);
                    Log.e(TAG, msg);
                } else {
                    String msg = "Bad package setting: package " + pp.name
                            + " has shared uid " + pp.sharedId
                            + " that is not defined\n";
                    mReadMessages.append(msg);
                    Log.e(TAG, msg);
                }
            }
            mPendingPackages.clear();

            N = mPendingPreferredPackages.size();
            mPreferredPackages.clear();
            for (int i=0; i<N; i++) {
                final String name = mPendingPreferredPackages.get(i);
                final PackageSetting p = mPackages.get(name);
                if (p != null) {
                    mPreferredPackages.add(p);
                } else {
                    Log.w(TAG, "Unknown preferred package: " + name);
                }
            }
            mPendingPreferredPackages.clear();

            mReadMessages.append("Read completed successfully: "
                    + mPackages.size() + " packages, "
                    + mSharedUsers.size() + " shared uids\n");

            return true;
        }

 

 

2.2.1 readPackageLP

// 解析 data/system/packages.xml 文件中的 "package"标签
        private void readPackageLP(XmlPullParser parser)
                throws XmlPullParserException, IOException {
            String name = null;
            String idStr = null;
            String sharedIdStr = null;
            String codePathStr = null;
            String resourcePathStr = null;
            String systemStr = null;
            String installerPackageName = null;
            int pkgFlags = 0;
            String timeStampStr;
            long timeStamp = 0;
            PackageSettingBase packageSetting = null;
            String version = null;
            int versionCode = 0;
            try {
                // name：包名
                name = parser.getAttributeValue(null, "name");
                idStr = parser.getAttributeValue(null, "userId");
                sharedIdStr = parser.getAttributeValue(null, "sharedUserId");
                codePathStr = parser.getAttributeValue(null, "codePath");
                resourcePathStr = parser.getAttributeValue(null, "resourcePath");
                version = parser.getAttributeValue(null, "version");
                if (version != null) {
                    try {
                        versionCode = Integer.parseInt(version);
                    } catch (NumberFormatException e) {
                    }
                }
                systemStr = parser.getAttributeValue(null, "system");
                // installer的值： com.google.android.packageinstaller or com.android.vending etc.
                installerPackageName = parser.getAttributeValue(null, "installer");
                if (systemStr != null) {
                    if ("true".equals(systemStr)) {
                        pkgFlags |= ApplicationInfo.FLAG_SYSTEM;
                    }
                } else {
                    // Old settings that don't specify system...  just treat
                    // them as system, good enough.
                    pkgFlags |= ApplicationInfo.FLAG_SYSTEM;
                }
                timeStampStr = parser.getAttributeValue(null, "ts"); // 解析时间戳
                if (timeStampStr != null) {
                    try {
                        timeStamp = Long.parseLong(timeStampStr);
                    } catch (NumberFormatException e) {
                    }
                }
                if (DEBUG_SETTINGS) Log.v(TAG, "Reading package: " + name
                        + " userId=" + idStr + " sharedUserId=" + sharedIdStr);
                int userId = idStr != null ? Integer.parseInt(idStr) : 0;
                if (resourcePathStr == null) {
                    // 若没有 resourcePath 属性，则赋值为 codePath 属性的值
                    resourcePathStr = codePathStr;
                }
                if (name == null) { // 没有包名
                    reportSettingsProblem(Log.WARN,
                            "Error in package manager settings: <package> has no name at "
                            + parser.getPositionDescription());
                } else if (codePathStr == null) { // 没有 codePath 属性值
                    reportSettingsProblem(Log.WARN,
                            "Error in package manager settings: <package> has no codePath at "
                            + parser.getPositionDescription());
                } else if (userId > 0) {
                    // 有包名、有codePathStr的值，且userId大于0
                    // 根据上述解析的信息，创建 PackageSettingBase 对象
                    packageSetting = addPackageLP(name.intern(), new File(codePathStr), 
                            new File(resourcePathStr), userId, versionCode, pkgFlags);
                    if (DEBUG_SETTINGS) Log.i(TAG, "Reading package " + name
                            + ": userId=" + userId + " pkg=" + packageSetting);
                    if (packageSetting == null) {
                        reportSettingsProblem(Log.ERROR,
                                "Failure adding uid " + userId
                                + " while parsing settings at "
                                + parser.getPositionDescription());
                    } else {
                        // 设置时间戳
                        packageSetting.setTimeStamp(timeStamp, timeStampStr);
                    }
                } else if (sharedIdStr != null) { // 存在 sharedUserId 的值
                    // 将 sharedUserId 的值赋值给 userId
                    userId = sharedIdStr != null
                            ? Integer.parseInt(sharedIdStr) : 0;
                    if (userId > 0) {
                        // 存在 sharedUserId的值 ，且 sharedUserId 大于0，创建 PendingPackage 对象
                        packageSetting = new PendingPackage(name.intern(), new File(codePathStr),
                                new File(resourcePathStr), userId, versionCode, pkgFlags);
                        packageSetting.setTimeStamp(timeStamp, timeStampStr);
                        // mPendingPackages 装入的是 存在 sharedUserId 值的 package 标签
                        mPendingPackages.add((PendingPackage) packageSetting);
                        if (DEBUG_SETTINGS) Log.i(TAG, "Reading package " + name
                                + ": sharedUserId=" + userId + " pkg="
                                + packageSetting);
                    } else { // sharedUserId 小于0，报告错误
                        reportSettingsProblem(Log.WARN,
                                "Error in package manager settings: package "
                                + name + " has bad sharedId " + sharedIdStr
                                + " at " + parser.getPositionDescription());
                    }
                } else { // userId 的值不符合，报告错误
                    reportSettingsProblem(Log.WARN,
                            "Error in package manager settings: package "
                            + name + " has bad userId " + idStr + " at "
                            + parser.getPositionDescription());
                }
            } catch (NumberFormatException e) {
                reportSettingsProblem(Log.WARN,
                        "Error in package manager settings: package "
                        + name + " has bad userId " + idStr + " at "
                        + parser.getPositionDescription());
            }
            if (packageSetting != null) { // 针对存在userId 或 sharedUserId 属性的 package标签
                packageSetting.installerPackageName = installerPackageName;
                final String enabledStr = parser.getAttributeValue(null, "enabled");
                if (enabledStr != null) { // 有 enabled 属性值
                    if (enabledStr.equalsIgnoreCase("true")) {
                        packageSetting.enabled = COMPONENT_ENABLED_STATE_ENABLED;
                    } else if (enabledStr.equalsIgnoreCase("false")) {
                        packageSetting.enabled = COMPONENT_ENABLED_STATE_DISABLED;
                    } else if (enabledStr.equalsIgnoreCase("default")) {
                        packageSetting.enabled = COMPONENT_ENABLED_STATE_DEFAULT;
                    } else {
                        reportSettingsProblem(Log.WARN,
                                "Error in package manager settings: package "
                                + name + " has bad enabled value: " + idStr
                                + " at " + parser.getPositionDescription());
                    }
                } else { // 无 enabled 属性
                    packageSetting.enabled = COMPONENT_ENABLED_STATE_DEFAULT;
                }
                final String installStatusStr = parser.getAttributeValue(null, "installStatus");
                if (installStatusStr != null) { // 有 installStatus 属性值
                    if (installStatusStr.equalsIgnoreCase("false")) {
                        packageSetting.installStatus = PKG_INSTALL_INCOMPLETE;
                    } else {
                        packageSetting.installStatus = PKG_INSTALL_COMPLETE;
                    }
                }
                
                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();
                    // 解析 package 标签下 的子标签
                    if (tagName.equals("disabled-components")) { // 解析子标签  disabled-components
                        readDisabledComponentsLP(packageSetting, parser);
                    } else if (tagName.equals("enabled-components")) {
                        readEnabledComponentsLP(packageSetting, parser); // 解析子标签  enabled-components
                    } else if (tagName.equals("sigs")) { // 解析子标签 sigs
                        packageSetting.signatures.readXml(parser, mPastSignatures);
                    } else if (tagName.equals("perms")) { // 解析子标签 perms
                        // 把解析的"权限名称"装入 packageSetting.loadedPermissions 集合中
                        readGrantedPermissionsLP(parser,
                                packageSetting.loadedPermissions);
                        packageSetting.permissionsFixed = true;
                    } else { // 报告错误
                        reportSettingsProblem(Log.WARN,
                                "Unknown element under <package>: "
                                + parser.getName());
                        XmlUtils.skipCurrentTag(parser);
                    }
                }
            } else {
                XmlUtils.skipCurrentTag(parser);
            }
        }

 

 

2.2.1.1 readDisabledComponentsLP

        // 解析"data/system/package.xml"文件中的 package 标签下的子标签 "disabled-components"
        private void readDisabledComponentsLP(PackageSettingBase packageSetting,
                                                  XmlPullParser parser)
                throws IOException, XmlPullParserException {
            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 (tagName.equals("item")) { // 解析子标签"item"
                    // 获取name属性值
                    String name = parser.getAttributeValue(null, "name");
                    if (name != null) {
                        // 装入到 disabledComponents 集合中
                        packageSetting.disabledComponents.add(name.intern());
                    } else {
                        reportSettingsProblem(Log.WARN,
                                "Error in package manager settings: <disabled-components> has"
                                + " no name at " + parser.getPositionDescription());
                    }
                } else {
                    reportSettingsProblem(Log.WARN,
                            "Unknown element under <disabled-components>: "
                            + parser.getName());
                }
                XmlUtils.skipCurrentTag(parser);
            }
        }

 

2.2.1.2 readEnabledComponentsLP

        // 解析"data/system/package.xml"文件中的 package 标签下的子标签 "enabled-components"
        private void readEnabledComponentsLP(PackageSettingBase packageSetting,
                                                  XmlPullParser parser)
                throws IOException, XmlPullParserException {
            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 (tagName.equals("item")) {
                    String name = parser.getAttributeValue(null, "name");
                    if (name != null) {
                        packageSetting.enabledComponents.add(name.intern());
                    } else {
                        reportSettingsProblem(Log.WARN,
                                "Error in package manager settings: <enabled-components> has"
                                   + " no name at " + parser.getPositionDescription());
                    }
                } else {
                    reportSettingsProblem(Log.WARN,
                            "Unknown element under <enabled-components>: "
                            + parser.getName());
                }
                XmlUtils.skipCurrentTag(parser);
            }
        }

 

2.2.1.3 readGrantedPermissionsLP

        // 解析标签 "perms"的值
        private void readGrantedPermissionsLP(XmlPullParser parser,
                HashSet<String> outPerms) throws IOException, XmlPullParserException {
            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 (tagName.equals("item")) { // 解析子标签 item
                    // name：权限名称
                    String name = parser.getAttributeValue(null, "name");
                    if (name != null) {
                        // 解析"权限名称"后装入 outPerms 中
                        outPerms.add(name.intern());
                    } else {
                        reportSettingsProblem(Log.WARN,
                                "Error in package manager settings: <perms> has"
                                   + " no name at " + parser.getPositionDescription());
                    }
                } else {
                    reportSettingsProblem(Log.WARN,
                            "Unknown element under <perms>: "
                            + parser.getName());
                }
                XmlUtils.skipCurrentTag(parser);
            }
        }

 

2.2.2 readPermissionsLP

// 解析 data/system/packages.xml 文件中的  permissions 标签和 permission-trees 标签
        private void readPermissionsLP(HashMap<String, BasePermission> out,
                XmlPullParser parser)
                throws IOException, XmlPullParserException {
            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 (tagName.equals("item")) {
                    String name = parser.getAttributeValue(null, "name");
                    String sourcePackage = parser.getAttributeValue(null, "package");
                    String ptype = parser.getAttributeValue(null, "type");
                    if (name != null && sourcePackage != null) {
                        boolean dynamic = "dynamic".equals(ptype);
                        BasePermission bp = new BasePermission(name, sourcePackage,
                                dynamic
                                ? BasePermission.TYPE_DYNAMIC
                                : BasePermission.TYPE_NORMAL);
                        if (dynamic) {
                            PermissionInfo pi = new PermissionInfo();
                            pi.packageName = sourcePackage.intern();
                            pi.name = name.intern();
                            pi.icon = readInt(parser, null, "icon", 0);
                            pi.nonLocalizedLabel = parser.getAttributeValue(
                                    null, "label");
                            pi.protectionLevel = readInt(parser, null, "protection",
                                    PermissionInfo.PROTECTION_NORMAL);
                            bp.pendingInfo = pi;
                        }
                        out.put(bp.name, bp);
                    } else {
                        reportSettingsProblem(Log.WARN,
                                "Error in package manager settings: permissions has"
                                + " no name at " + parser.getPositionDescription());
                    }
                } else {
                    reportSettingsProblem(Log.WARN,
                            "Unknown element reading permissions: "
                            + parser.getName() + " at "
                            + parser.getPositionDescription());
                }
                XmlUtils.skipCurrentTag(parser);
            }
        }

 

 

2.2.3 readSharedUserLP

// 解析"data/system/package.xml"文件中的 shared-user 标签
        private void readSharedUserLP(XmlPullParser parser)
                throws XmlPullParserException, IOException {
            String name = null;
            String idStr = null;
            int pkgFlags = 0;
            SharedUserSetting su = null;
            try {
                name = parser.getAttributeValue(null, "name");// 解析name属性值
                idStr = parser.getAttributeValue(null, "userId");// 解析 userId 属性值
                int userId = idStr != null ? Integer.parseInt(idStr) : 0;
                if ("true".equals(parser.getAttributeValue(null, "system"))) {
                    pkgFlags |= ApplicationInfo.FLAG_SYSTEM;
                }
                if (name == null) {
                    reportSettingsProblem(Log.WARN,
                            "Error in package manager settings: <shared-user> has no name at "
                            + parser.getPositionDescription());
                } else if (userId == 0) {
                    reportSettingsProblem(Log.WARN,
                            "Error in package manager settings: shared-user "
                            + name + " has bad userId " + idStr + " at "
                            + parser.getPositionDescription());
                } else {
                    if ((su=addSharedUserLP(name.intern(), userId, pkgFlags)) == null) {
                        reportSettingsProblem(Log.ERROR,
                                "Occurred while parsing settings at "
                                + parser.getPositionDescription());
                    }
                }
            } catch (NumberFormatException e) {
                reportSettingsProblem(Log.WARN,
                        "Error in package manager settings: package "
                        + name + " has bad userId " + idStr + " at "
                        + parser.getPositionDescription());
            };

            if (su != null) {
                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 (tagName.equals("sigs")) { // 解析 sigs 子标签
                        su.signatures.readXml(parser, mPastSignatures);
                    } else if (tagName.equals("perms")) { // 解析 perms 标签
                        readGrantedPermissionsLP(parser, su.loadedPermissions);
                    } else {
                        reportSettingsProblem(Log.WARN,
                                "Unknown element under <shared-user>: "
                                + parser.getName());
                        XmlUtils.skipCurrentTag(parser);
                    }
                }

            } else {
                XmlUtils.skipCurrentTag(parser);
            }
        }

 

 

2.2.4 readDisabledSysPackageLP

// 解析 packages.xml 文件中的 updated-package 标签值 
        private void readDisabledSysPackageLP(XmlPullParser parser)
        throws XmlPullParserException, IOException {
            String name = parser.getAttributeValue(null, "name");
            String codePathStr = parser.getAttributeValue(null, "codePath");
            String resourcePathStr = parser.getAttributeValue(null, "resourcePath");
            // 如果 resourcePathStr 没有值
            if(resourcePathStr == null) {
                // 则赋值为 codePath的值
                resourcePathStr = codePathStr;
            }
            String version = parser.getAttributeValue(null, "version");
            int versionCode = 0;
            // 如果有 version 的值
            if (version != null) {
                try {
                    // 则解析version的值
                    versionCode = Integer.parseInt(version);
                } catch (NumberFormatException e) {
                }
            }
            
            int pkgFlags = 0;
            pkgFlags |= ApplicationInfo.FLAG_SYSTEM;
            // 根据上述 解析的信息，创建  PackageSetting 对象
            // name：包名
            // codePathStr：com.google.android.gms
            PackageSetting ps = new PackageSetting(name, 
                    new File(codePathStr), 
                    new File(resourcePathStr), versionCode, pkgFlags);
            String timeStampStr = parser.getAttributeValue(null, "ts");
            if (timeStampStr != null) {
                try {
                    // 如果有时间戳信息，则解析时间戳
                    long timeStamp = Long.parseLong(timeStampStr);
                    // 设置时间戳
                    ps.setTimeStamp(timeStamp, timeStampStr);
                } catch (NumberFormatException e) {
                }
            }
            // 解析 userId的值
            String idStr = parser.getAttributeValue(null, "userId");
            ps.userId = idStr != null ? Integer.parseInt(idStr) : 0; // 设置 userId
            if(ps.userId <= 0) {
                // 如果 userId 小于0,则取值于 sharedUserId 的值
                String sharedIdStr = parser.getAttributeValue(null, "sharedUserId");
                ps.userId = sharedIdStr != null ? Integer.parseInt(sharedIdStr) : 0;
            }
            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();
                // 解析 updated-package 标签内的子标签"perms"
                if (tagName.equals("perms")) {
                    // ps.grantedPermissions 内装入的是子标签"perms"中声明的"权限名称"
                    readGrantedPermissionsLP(parser,
                            ps.grantedPermissions);
                } else {
                    reportSettingsProblem(Log.WARN,
                            "Unknown element under <updated-package>: "
                            + parser.getName());
                    XmlUtils.skipCurrentTag(parser);
                }
            }
            // name:包名，根据包名转入 PackageSetting对象
            mDisabledSysPackages.put(name, ps);
        }

 

 

2.3 scanDirLI

    // 扫描：system/app目录、system/framework目录、data/app目录、data/app-private目录
    private void scanDirLI(File dir, int flags, int scanMode) {
        Log.d(TAG, "Scanning app dir " + dir);

        String[] files = dir.list();

        int i;
        for (i=0; i<files.length; i++) {
            File file = new File(dir, files[i]);
            File resFile = file;
            // Pick up the resource path from settings for fwd locked apps
            if ((scanMode & SCAN_FORWARD_LOCKED) != 0) {  // data/app-private目录 ?
                resFile = null;
            }
            // 第1个参数、第2个参数和第3个参数，大多时候同一个值
            PackageParser.Package pkg = scanPackageLI(file, file, resFile,
                    flags|PackageParser.PARSE_MUST_BE_APK, scanMode);
        }
    }

 

 

2.3.1 scanPackageLI

/*
     *  Scan a package and return the newly parsed package.
     *  Returns null in case of errors and the error code is stored in mLastScanError
     */
    private PackageParser.Package scanPackageLI(File scanFile,
            File destCodeFile, File destResourceFile, int parseFlags,
            int scanMode) {
        mLastScanError = PackageManager.INSTALL_SUCCEEDED;
        parseFlags |= mDefParseFlags;
        PackageParser pp = new PackageParser(scanFile.getPath());
        pp.setSeparateProcesses(mSeparateProcesses);
        pp.setSdkVersion(mSdkVersion, mSdkCodename);
        // 解析包，主要是解析 AndroidManifest.xml 文件
        final PackageParser.Package pkg = pp.parsePackage(scanFile,
                destCodeFile.getAbsolutePath(), mMetrics, parseFlags);
        if (pkg == null) { // 解析异常，直接返回
            mLastScanError = pp.getParseError();
            return null;
        }
        PackageSetting ps;
        PackageSetting updatedPkg;
        synchronized (mPackages) {
            ps = mSettings.peekPackageLP(pkg.packageName);
            updatedPkg = mSettings.mDisabledSysPackages.get(pkg.packageName);
        }
        ///// 首先验证APK签名信息，如果验证出现问题，则直接返回
        // Verify certificates first
        if (!collectCertificatesLI(pp, ps, pkg, scanFile, parseFlags)) {
            Log.i(TAG, "Failed verifying certificates for package:" + pkg.packageName);
            return null;
        }
        if (updatedPkg != null) {
            // An updated system app will not have the PARSE_IS_SYSTEM flag set initially
            parseFlags |= PackageParser.PARSE_IS_SYSTEM;
        }
        if ((parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0) {
            // Check for updated system applications here
            if (updatedPkg != null) {
                if ((ps != null) && (!ps.codePath.getPath().equals(scanFile.getPath()))) {
                    if (pkg.mVersionCode <= ps.versionCode) { // 版本号对比：和 mSettings 集合中搜索出来的包进行对比
                     // The system package has been updated and the code path does not match
                        // Ignore entry. Just return
                        Log.w(TAG, "Package:" + pkg.packageName +
                                " has been updated. Ignoring the one from path:"+scanFile);
                        mLastScanError = PackageManager.INSTALL_FAILED_DUPLICATE_PACKAGE;
                        return null;
                    } else {
                        // Delete the older apk pointed to by ps
                        // At this point, its safely assumed that package installation for
                        // apps in system partition will go through. If not there won't be a working
                        // version of the app
                        synchronized (mPackages) {
                            // Just remove the loaded entries from package lists.
                            mPackages.remove(ps.name);
                        }
                        // 删除资源包
                        deletePackageResourcesLI(ps.name, ps.codePathString, ps.resourcePathString);
                        mSettings.enableSystemPackageLP(ps.name);
                    }
                }
            }
        }
        // The apk is forward locked (not public) if its code and resources
        // are kept in different files.
        if (ps != null && !ps.codePath.equals(ps.resourcePath)) { // code 路径和 resourcePath 路径保存位置不同
            scanMode |= SCAN_FORWARD_LOCKED;
        }
        File resFile = destResourceFile;
        if ((scanMode & SCAN_FORWARD_LOCKED) != 0) {
            resFile = getFwdLockedResource(ps.name);
        }
        // Note that we invoke the following method only if we are about to unpack an application
        return scanPackageLI(scanFile, destCodeFile, resFile,
                pkg, parseFlags, scanMode | SCAN_UPDATE_SIGNATURE);
    }

 

# PackageParser.java

 2.3.1.1 parsePackage

public Package parsePackage(File sourceFile, String destFileName,
            DisplayMetrics metrics, int flags) {
        // 默认值：安装成功
        mParseError = PackageManager.INSTALL_SUCCEEDED;

        // 拿到文件路径
        mArchiveSourcePath = sourceFile.getPath();
        if (!sourceFile.isFile()) {// 过滤出目录
            Log.w(TAG, "Skipping dir: " + mArchiveSourcePath);
            mParseError = PackageManager.INSTALL_PARSE_FAILED_NOT_APK;
            return null;
        }
        // 判断是否是APK文件，如果不是apk文件，则直接返回
        if (!isPackageFilename(sourceFile.getName())
                && (flags&PARSE_MUST_BE_APK) != 0) {
            if ((flags&PARSE_IS_SYSTEM) == 0) {
                // We expect to have non-.apk files in the system dir,
                // so don't warn about them.
                Log.w(TAG, "Skipping non-package file: " + mArchiveSourcePath);
            }
            mParseError = PackageManager.INSTALL_PARSE_FAILED_NOT_APK;
            return null;
        }

        if ((flags&PARSE_CHATTY) != 0 && Config.LOGD) Log.d(
            TAG, "Scanning package: " + mArchiveSourcePath);

        XmlResourceParser parser = null;
        AssetManager assmgr = null;
        boolean assetError = true;
        try {
            assmgr = new AssetManager();
            // 将apk文件加入装入
            int cookie = assmgr.addAssetPath(mArchiveSourcePath);
            if(cookie != 0) {// 文件装入OK
                parser = assmgr.openXmlResourceParser(cookie, "AndroidManifest.xml");// 打开 AndroidManifest.xml 文件
                assetError = false;
            } else {
                Log.w(TAG, "Failed adding asset path:"+mArchiveSourcePath);
            }
        } catch (Exception e) {
            Log.w(TAG, "Unable to read AndroidManifest.xml of "
                    + mArchiveSourcePath, e);
        }
        if(assetError) { // 打开 AndroidManifest.xml 出现错误，直接返回
            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.
            Resources res = new Resources(assmgr, metrics, null);
            ////////// 解析 AndroidManifest.xml 文件
            pkg = parsePackage(res, parser, flags, errorText);
        } catch (Exception e) {
            errorException = e;
            mParseError = PackageManager.INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION;
        }


        // 解析包出错，释放资源，直接返回
        if (pkg == null) {
            if (errorException != null) {
                Log.w(TAG, mArchiveSourcePath, errorException);
            } else {
                Log.w(TAG, mArchiveSourcePath + " (at "
                        + parser.getPositionDescription()
                        + "): " + errorText[0]);
            }
            parser.close();
            assmgr.close();
            if (mParseError == PackageManager.INSTALL_SUCCEEDED) {
                mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
            }
            return null;
        }

        parser.close();
        assmgr.close();

        // 赋值 sourceDir 和 publicSourceDir
        pkg.applicationInfo.sourceDir = destFileName;
        pkg.applicationInfo.publicSourceDir = destFileName;
        pkg.mSignatures = null;

        return pkg;
    }

 

2.3.1.1.1  parsePackage

 // 解析 AndroidManifest.xml 文件
    private Package parsePackage(
        Resources res, XmlResourceParser parser, int flags, String[] outError)
        throws XmlPullParserException, IOException {
        AttributeSet attrs = parser;

        mParseInstrumentationArgs = null;
        mParseActivityArgs = null;
        mParseServiceArgs = null;
        mParseProviderArgs = null;
        
        // 从 AndroidManifest.xml 文件中解析包名
        String pkgName = parsePackageName(parser, attrs, flags, outError);
        if (pkgName == null) { // 没有拿到包名
            mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_PACKAGE_NAME;
            return null;
        }
        int type;

        // 根据 “包名” 新建 Package 对象
        final Package pkg = new Package(pkgName);
        boolean foundApp = false;
        
        TypedArray sa = res.obtainAttributes(attrs,
                com.android.internal.R.styleable.AndroidManifest);
        // 获取 versionCode 属性值
        pkg.mVersionCode = sa.getInteger(
                com.android.internal.R.styleable.AndroidManifest_versionCode, 0);
        // 获取 versionName 属性值
        pkg.mVersionName = sa.getNonResourceString(
                com.android.internal.R.styleable.AndroidManifest_versionName);
        if (pkg.mVersionName != null) {
            pkg.mVersionName = pkg.mVersionName.intern();
        }
        // 获取 sharedUserId 属性值
        String str = sa.getNonResourceString(
                com.android.internal.R.styleable.AndroidManifest_sharedUserId);
        if (str != null) {// 如果存在 sharedUserId 属性值
            String nameError = validateName(str, true);
            if (nameError != null && !"android".equals(pkgName)) {
                outError[0] = "<manifest> specifies bad sharedUserId name \""
                    + str + "\": " + nameError;
                mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_SHARED_USER_ID;
                return null;
            }
            // 将 sharedUserId 的值赋值给 Package 对象
            pkg.mSharedUserId = str.intern();
            // 获取 sharedUserLabel 属性值
            pkg.mSharedUserLabel = sa.getResourceId(
                    com.android.internal.R.styleable.AndroidManifest_sharedUserLabel, 0);
        }
        sa.recycle(); // TypedArray资源回收

        // Resource boolean are -1, so 1 means we don't know the value.
        int supportsSmallScreens = 1;
        int supportsNormalScreens = 1;
        int supportsLargeScreens = 1;
        int resizeable = 1;
        int anyDensity = 1;
        
        int outerDepth = parser.getDepth();
        while ((type=parser.next()) != parser.END_DOCUMENT
               && (type != parser.END_TAG || parser.getDepth() > outerDepth)) {
            if (type == parser.END_TAG || type == parser.TEXT) {
                continue;
            }

            String tagName = parser.getName();
            // 从 AndroidManifest.xml 文件中解析 application 标签
            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 {
                        Log.w(TAG, "<manifest> has more than one <application>");
                        XmlUtils.skipCurrentTag(parser);
                        continue;
                    }
                }

                foundApp = true;
                // 解析 application 标签
                if (!parseApplication(pkg, res, parser, attrs, flags, outError)) {
                    return null;
                }
                // 解析 permission-group 标签
            } else if (tagName.equals("permission-group")) {
                if (parsePermissionGroup(pkg, res, parser, attrs, outError) == null) {
                    return null;
                }
                // 解析 permission 标签
            } else if (tagName.equals("permission")) {
                if (parsePermission(pkg, res, parser, attrs, outError) == null) {
                    return null;
                }
                // 解析 permission-tree 标签
            } else if (tagName.equals("permission-tree")) {
                if (parsePermissionTree(pkg, res, parser, attrs, outError) == null) {
                    return null;
                }
                // 解析 uses-permission 标签
            } else if (tagName.equals("uses-permission")) {
                sa = res.obtainAttributes(attrs,
                        com.android.internal.R.styleable.AndroidManifestUsesPermission);

                String name = sa.getNonResourceString(
                        com.android.internal.R.styleable.AndroidManifestUsesPermission_name);

                sa.recycle();

                if (name != null && !pkg.requestedPermissions.contains(name)) {
                    pkg.requestedPermissions.add(name.intern());
                }

                XmlUtils.skipCurrentTag(parser);

                // 解析 uses-configuration 标签
            } else if (tagName.equals("uses-configuration")) {
                ConfigurationInfo cPref = new ConfigurationInfo();
                sa = res.obtainAttributes(attrs,
                        com.android.internal.R.styleable.AndroidManifestUsesConfiguration);
                cPref.reqTouchScreen = sa.getInt(
                        com.android.internal.R.styleable.AndroidManifestUsesConfiguration_reqTouchScreen,
                        Configuration.TOUCHSCREEN_UNDEFINED);
                cPref.reqKeyboardType = sa.getInt(
                        com.android.internal.R.styleable.AndroidManifestUsesConfiguration_reqKeyboardType,
                        Configuration.KEYBOARD_UNDEFINED);
                if (sa.getBoolean(
                        com.android.internal.R.styleable.AndroidManifestUsesConfiguration_reqHardKeyboard,
                        false)) {
                    cPref.reqInputFeatures |= ConfigurationInfo.INPUT_FEATURE_HARD_KEYBOARD;
                }
                cPref.reqNavigation = sa.getInt(
                        com.android.internal.R.styleable.AndroidManifestUsesConfiguration_reqNavigation,
                        Configuration.NAVIGATION_UNDEFINED);
                if (sa.getBoolean(
                        com.android.internal.R.styleable.AndroidManifestUsesConfiguration_reqFiveWayNav,
                        false)) {
                    cPref.reqInputFeatures |= ConfigurationInfo.INPUT_FEATURE_FIVE_WAY_NAV;
                }
                sa.recycle();
                pkg.configPreferences.add(cPref);

                XmlUtils.skipCurrentTag(parser);
                // 解析 uses-feature 标签
            } else if (tagName.equals("uses-feature")) {
                ConfigurationInfo cPref = new ConfigurationInfo();
                sa = res.obtainAttributes(attrs,
                        com.android.internal.R.styleable.AndroidManifestUsesFeature);
                cPref.reqGlEsVersion = sa.getInt(
                        com.android.internal.R.styleable.AndroidManifestUsesFeature_glEsVersion,
                        ConfigurationInfo.GL_ES_VERSION_UNDEFINED);
                sa.recycle();
                pkg.configPreferences.add(cPref);

                XmlUtils.skipCurrentTag(parser);

                // 解析 uses-sdk 标签
            } else if (tagName.equals("uses-sdk")) {
                if (mSdkVersion > 0) {
                    sa = res.obtainAttributes(attrs,
                            com.android.internal.R.styleable.AndroidManifestUsesSdk);

                    int minVers = 0;
                    String minCode = null;
                    int targetVers = 0;
                    String targetCode = null;
                    
                    // 解析 minSdkVersion 属性值
                    TypedValue val = sa.peekValue(
                            com.android.internal.R.styleable.AndroidManifestUsesSdk_minSdkVersion);
                    if (val != null) { // 数值和字串区别
                        if (val.type == TypedValue.TYPE_STRING && val.string != null) {
                            targetCode = minCode = val.string.toString();
                        } else {
                            // If it's not a string, it's an integer.
                            targetVers = minVers = val.data;
                        }
                    }
                    
                    // 解析 targetSdkVersion 属性
                    val = sa.peekValue(
                            com.android.internal.R.styleable.AndroidManifestUsesSdk_targetSdkVersion);
                    if (val != null) { // 数值和字串区别
                        if (val.type == TypedValue.TYPE_STRING && val.string != null) {
                            targetCode = minCode = val.string.toString();
                        } else {
                            // If it's not a string, it's an integer.
                            targetVers = val.data;
                        }
                    }
                    
                    // 解析 maxSdkVersion 属性
                    int maxVers = sa.getInt(
                            com.android.internal.R.styleable.AndroidManifestUsesSdk_maxSdkVersion,
                            mSdkVersion);

                    sa.recycle();

                    if (minCode != null) {
                        if (!minCode.equals(mSdkCodename)) {
                            if (mSdkCodename != null) {
                                outError[0] = "Requires development platform " + minCode
                                        + " (current platform is " + mSdkCodename + ")";
                            } else {
                                outError[0] = "Requires development platform " + minCode
                                        + " but this is a release platform.";
                            }
                            mParseError = PackageManager.INSTALL_FAILED_OLDER_SDK;
                            return null;
                        }
                    } else if (minVers > mSdkVersion) {
                        outError[0] = "Requires newer sdk version #" + minVers
                                + " (current version is #" + mSdkVersion + ")";
                        mParseError = PackageManager.INSTALL_FAILED_OLDER_SDK;
                        return null;
                    }
                    
                    if (targetCode != null) {
                        if (!targetCode.equals(mSdkCodename)) {
                            if (mSdkCodename != null) {
                                outError[0] = "Requires development platform " + targetCode
                                        + " (current platform is " + mSdkCodename + ")";
                            } else {
                                outError[0] = "Requires development platform " + targetCode
                                        + " but this is a release platform.";
                            }
                            mParseError = PackageManager.INSTALL_FAILED_OLDER_SDK;
                            return null;
                        }
                        // If the code matches, it definitely targets this SDK.
                        pkg.applicationInfo.targetSdkVersion
                                = android.os.Build.VERSION_CODES.CUR_DEVELOPMENT;
                    } else {
                        pkg.applicationInfo.targetSdkVersion = targetVers;
                    }
                    
                    if (maxVers < mSdkVersion) {
                        outError[0] = "Requires older sdk version #" + maxVers
                                + " (current version is #" + mSdkVersion + ")";
                        mParseError = PackageManager.INSTALL_FAILED_OLDER_SDK;
                        return null;
                    }
                }

                XmlUtils.skipCurrentTag(parser);

                // 解析 supports-screens 标签
            } else if (tagName.equals("supports-screens")) {
                sa = res.obtainAttributes(attrs,
                        com.android.internal.R.styleable.AndroidManifestSupportsScreens);

                // This is a trick to get a boolean and still able to detect
                // if a value was actually set.
                supportsSmallScreens = sa.getInteger(
                        com.android.internal.R.styleable.AndroidManifestSupportsScreens_smallScreens,
                        supportsSmallScreens);
                supportsNormalScreens = sa.getInteger(
                        com.android.internal.R.styleable.AndroidManifestSupportsScreens_normalScreens,
                        supportsNormalScreens);
                supportsLargeScreens = sa.getInteger(
                        com.android.internal.R.styleable.AndroidManifestSupportsScreens_largeScreens,
                        supportsLargeScreens);
                resizeable = sa.getInteger(
                        com.android.internal.R.styleable.AndroidManifestSupportsScreens_resizeable,
                        supportsLargeScreens);
                anyDensity = sa.getInteger(
                        com.android.internal.R.styleable.AndroidManifestSupportsScreens_anyDensity,
                        anyDensity);

                sa.recycle();
                
                XmlUtils.skipCurrentTag(parser);
                // 解析protected-broadcast 标签
            } else if (tagName.equals("protected-broadcast")) {
                sa = res.obtainAttributes(attrs,
                        com.android.internal.R.styleable.AndroidManifestProtectedBroadcast);

                String name = sa.getNonResourceString(
                        com.android.internal.R.styleable.AndroidManifestProtectedBroadcast_name);

                sa.recycle();

                if (name != null && (flags&PARSE_IS_SYSTEM) != 0) {
                    if (pkg.protectedBroadcasts == null) {
                        pkg.protectedBroadcasts = new ArrayList<String>();
                    }
                    if (!pkg.protectedBroadcasts.contains(name)) {
                        pkg.protectedBroadcasts.add(name.intern());
                    }
                }

                XmlUtils.skipCurrentTag(parser);
                // 解析 instrumentation 标签
            } else if (tagName.equals("instrumentation")) {
                if (parseInstrumentation(pkg, res, parser, attrs, outError) == null) {
                    return null;
                }
                // 解析 eat-comment 标签
            } else if (tagName.equals("eat-comment")) {
                // Just skip this tag
                XmlUtils.skipCurrentTag(parser);
                continue;
                
            } else if (RIGID_PARSER) { // 打印log信息
                outError[0] = "Bad element under <manifest>: "
                    + parser.getName();
                mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
                return null;

            } else { // 打印log信息
                Log.w(TAG, "Bad element under <manifest>: "
                      + parser.getName());
                XmlUtils.skipCurrentTag(parser);
                continue;
            }
        }

        if (!foundApp && pkg.instrumentation.size() == 0) { // 没有发现 <application> 标签 或 <instrumentation> 标签
            outError[0] = "<manifest> does not contain an <application> or <instrumentation>";
            mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_EMPTY;
        }

        final int NP = PackageParser.NEW_PERMISSIONS.length;
        for (int ip=0; ip<NP; ip++) {
            final PackageParser.NewPermissionInfo npi
                    = PackageParser.NEW_PERMISSIONS[ip];
            if (pkg.applicationInfo.targetSdkVersion >= npi.sdkVersion) {
                break;
            }
            if (!pkg.requestedPermissions.contains(npi.name)) {
                Log.i(TAG, "Impliciting adding " + npi.name + " to old pkg "
                        + pkg.packageName);
                pkg.requestedPermissions.add(npi.name);
            }
        }
        
        if (pkg.usesLibraries.size() > 0) {
            pkg.usesLibraryFiles = new String[pkg.usesLibraries.size()];
            pkg.usesLibraries.toArray(pkg.usesLibraryFiles);
        }
        
        if (supportsSmallScreens < 0 || (supportsSmallScreens > 0
                && pkg.applicationInfo.targetSdkVersion
                        >= android.os.Build.VERSION_CODES.DONUT)) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_SUPPORTS_SMALL_SCREENS;
        }
        if (supportsNormalScreens != 0) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_SUPPORTS_NORMAL_SCREENS;
        }
        if (supportsLargeScreens < 0 || (supportsLargeScreens > 0
                && pkg.applicationInfo.targetSdkVersion
                        >= android.os.Build.VERSION_CODES.DONUT)) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_SUPPORTS_LARGE_SCREENS;
        }
        if (resizeable < 0 || (resizeable > 0
                && pkg.applicationInfo.targetSdkVersion
                        >= android.os.Build.VERSION_CODES.DONUT)) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_RESIZEABLE_FOR_SCREENS;
        }
        if (anyDensity < 0 || (anyDensity > 0
                && pkg.applicationInfo.targetSdkVersion
                        >= android.os.Build.VERSION_CODES.DONUT)) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_SUPPORTS_SCREEN_DENSITIES;
        }

        return pkg;
    }

2.3.1.2 collectCertificatesLI

    private boolean collectCertificatesLI(PackageParser pp, PackageSetting ps,
            PackageParser.Package pkg, File srcFile, int parseFlags) {
        if (GET_CERTIFICATES) {
            if (ps == null || !ps.codePath.equals(srcFile)
                    || ps.getTimeStamp() != srcFile.lastModified()) {
                // 源文件已经改变，再次收集证书
                Log.i(TAG, srcFile.toString() + " changed; collecting certs");
                // 收集证书
                if (!pp.collectCertificates(pkg, parseFlags)) {
                    mLastScanError = pp.getParseError();
                    return false;
                }
            }
        }
        return true;
    }

 

 

2.3.1.3 deletePackageResourcesLI

    private void deletePackageResourcesLI(String packageName,
            String sourceDir, String publicSourceDir) {
        File sourceFile = new File(sourceDir);
        if (!sourceFile.exists()) {
            Log.w(TAG, "Package source " + sourceDir + " does not exist.");
        }
        // 删除文件
        // Delete application's code and resources
        sourceFile.delete();
        final File publicSourceFile = new File(publicSourceDir);
        if (publicSourceFile.exists()) {
            publicSourceFile.delete();
        }
        if (mInstaller != null) {
            // 通过 mInstaller 删除dex文件 
            int retCode = mInstaller.rmdex(sourceFile.toString());
            if (retCode < 0) {
                Log.w(TAG, "Couldn't remove dex file for package: "
                        + packageName + " at location " + sourceFile.toString() + ", retcode=" + retCode);
                // we don't consider this to be a failure of the core package deletion
            }
        }
    }

 

 

2.3.1.4 scanPackageLI

private PackageParser.Package scanPackageLI(
        File scanFile, File destCodeFile, File destResourceFile,
        PackageParser.Package pkg, int parseFlags, int scanMode) {

        mScanningPath = scanFile;
        if (pkg == null) { // pkg传入的是null，直接返回
            mLastScanError = PackageManager.INSTALL_PARSE_FAILED_BAD_PACKAGE_NAME;
            return null;
        }

        final String pkgName = pkg.applicationInfo.packageName;
        if ((parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_SYSTEM;
        }

        if (pkgName.equals("android")) { // android包
            synchronized (mPackages) {
                if (mAndroidApplication != null) { // 已经解析过了，不再解析
                    Log.w(TAG, "*************************************************");
                    Log.w(TAG, "Core android package being redefined.  Skipping.");
                    Log.w(TAG, " file=" + mScanningPath);
                    Log.w(TAG, "*************************************************");
                    mLastScanError = PackageManager.INSTALL_FAILED_DUPLICATE_PACKAGE;
                    return null;
                }
    
                // 第一次解析
                // Set up information for our fall-back user intent resolution
                // activity.
                mPlatformPackage = pkg; // 保存平台包信息
                pkg.mVersionCode = mSdkVersion;
                mAndroidApplication = pkg.applicationInfo;
                //### ResolverActivity 这个activity 赋值的地方
                mResolveActivity.applicationInfo = mAndroidApplication;
                mResolveActivity.name = ResolverActivity.class.getName();
                mResolveActivity.packageName = mAndroidApplication.packageName;
                mResolveActivity.processName = mAndroidApplication.processName;
                mResolveActivity.launchMode = ActivityInfo.LAUNCH_MULTIPLE;
                mResolveActivity.flags = ActivityInfo.FLAG_EXCLUDE_FROM_RECENTS;
                mResolveActivity.theme = com.android.internal.R.style.Theme_Dialog_Alert;
                mResolveActivity.exported = true;
                mResolveActivity.enabled = true;
                mResolveInfo.activityInfo = mResolveActivity;
                mResolveInfo.priority = 0;
                mResolveInfo.preferredOrder = 0;
                mResolveInfo.match = 0;
                // 构建 ResolverActivity 这个activity的ComponentName
                mResolveComponentName = new ComponentName(
                        mAndroidApplication.packageName, mResolveActivity.name);
            }
        }

        if ((parseFlags&PackageParser.PARSE_CHATTY) != 0 && Config.LOGD) Log.d(
                TAG, "Scanning package " + pkgName);
        if (mPackages.containsKey(pkgName) || mSharedLibraries.containsKey(pkgName)) {
            Log.w(TAG, "*************************************************");
            Log.w(TAG, "Application package " + pkgName
                    + " already installed.  Skipping duplicate.");
            Log.w(TAG, "*************************************************");
            mLastScanError = PackageManager.INSTALL_FAILED_DUPLICATE_PACKAGE;
            return null;
        }

        SharedUserSetting suid = null;
        PackageSetting pkgSetting = null;
        
        boolean removeExisting = false;
        
        synchronized (mPackages) {
            // Check all shared libraries and map to their actual file path.
            if (pkg.usesLibraryFiles != null) {
                for (int i=0; i<pkg.usesLibraryFiles.length; i++) {
                    String file = mSharedLibraries.get(pkg.usesLibraryFiles[i]);
                    if (file == null) {
                        Log.e(TAG, "Package " + pkg.packageName
                                + " requires unavailable shared library "
                                + pkg.usesLibraryFiles[i] + "; ignoring!");
                        mLastScanError = PackageManager.INSTALL_FAILED_MISSING_SHARED_LIBRARY;
                        return null;
                    }
                    pkg.usesLibraryFiles[i] = file;
                }
            }
            
            if (pkg.mSharedUserId != null) {
                suid = mSettings.getSharedUserLP(pkg.mSharedUserId,
                        pkg.applicationInfo.flags, true);
                if (suid == null) {
                    Log.w(TAG, "Creating application package " + pkgName
                            + " for shared user failed");
                    mLastScanError = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
                    return null;
                }
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0 && Config.LOGD) {
                    Log.d(TAG, "Shared UserID " + pkg.mSharedUserId + " (uid="
                            + suid.userId + "): packages=" + suid.packages);
                }
            }

            // Just create the setting, don't add it yet. For already existing packages
            // the PkgSetting exists already and doesn't have to be created.
            pkgSetting = mSettings.getPackageLP(pkg, suid, destCodeFile,
                            destResourceFile, pkg.applicationInfo.flags, true, false);
            if (pkgSetting == null) {
                Log.w(TAG, "Creating application package " + pkgName + " failed");
                mLastScanError = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
                return null;
            }
            if(mSettings.mDisabledSysPackages.get(pkg.packageName) != null) {
                pkg.applicationInfo.flags |= ApplicationInfo.FLAG_UPDATED_SYSTEM_APP;
            }
        
            pkg.applicationInfo.uid = pkgSetting.userId;
            pkg.mExtras = pkgSetting;
    
            // 校验签名
            if (!verifySignaturesLP(pkgSetting, pkg, parseFlags, 
                    (scanMode&SCAN_UPDATE_SIGNATURE) != 0)) {
                if ((parseFlags&PackageParser.PARSE_IS_SYSTEM) == 0) {
                    mLastScanError = PackageManager.INSTALL_FAILED_UPDATE_INCOMPATIBLE;
                    return null;
                }
                // The signature has changed, but this package is in the system
                // image...  let's recover!
                pkgSetting.signatures.mSignatures = pkg.mSignatures;
                // However...  if this package is part of a shared user, but it
                // doesn't match the signature of the shared user, let's fail.
                // What this means is that you can't change the signatures
                // associated with an overall shared user, which doesn't seem all
                // that unreasonable.
                if (pkgSetting.sharedUser != null) {
                    if (!pkgSetting.sharedUser.signatures.mergeSignatures(
                            pkg.mSignatures, false)) {
                        mLastScanError = PackageManager.INSTALL_PARSE_FAILED_INCONSISTENT_CERTIFICATES;
                        return null;
                    }
                }
                removeExisting = true;
            }
            
            // Verify that this new package doesn't have any content providers
            // that conflict with existing packages.  Only do this if the
            // package isn't already installed, since we don't want to break
            // things that are installed.
            if ((scanMode&SCAN_NEW_INSTALL) != 0) { // 检查 content provider 避免冲突
                int N = pkg.providers.size();
                int i;
                for (i=0; i<N; i++) {
                    PackageParser.Provider p = pkg.providers.get(i);
                    String names[] = p.info.authority.split(";");
                    for (int j = 0; j < names.length; j++) {
                        if (mProviders.containsKey(names[j])) {
                            PackageParser.Provider other = mProviders.get(names[j]);
                            Log.w(TAG, "Can't install because provider name " + names[j] +
                                    " (in package " + pkg.applicationInfo.packageName +
                                    ") is already used by "
                                    + ((other != null && other.component != null)
                                            ? other.component.getPackageName() : "?"));
                            mLastScanError = PackageManager.INSTALL_FAILED_CONFLICTING_PROVIDER;
                            return null;
                        }
                    }
                }
            }
        }

        if (removeExisting) {
            if (mInstaller != null) {
                int ret = mInstaller.remove(pkgName);
                if (ret != 0) {
                    String msg = "System package " + pkg.packageName
                            + " could not have data directory erased after signature change.";
                    reportSettingsProblem(Log.WARN, msg);
                    mLastScanError = PackageManager.INSTALL_FAILED_REPLACE_COULDNT_DELETE;
                    return null;
                }
            }
            Log.w(TAG, "System package " + pkg.packageName
                    + " signature changed: existing data removed.");
            mLastScanError = PackageManager.INSTALL_SUCCEEDED;
        }
        
        // 文件时间戳比对
        long scanFileTime = scanFile.lastModified();
        final boolean forceDex = (scanMode&SCAN_FORCE_DEX) != 0;
        final boolean scanFileNewer = forceDex || scanFileTime != pkgSetting.getTimeStamp();
        pkg.applicationInfo.processName = fixProcessName(
                pkg.applicationInfo.packageName,
                pkg.applicationInfo.processName,
                pkg.applicationInfo.uid);
        pkg.applicationInfo.publicSourceDir = destResourceFile.toString();

        File dataPath;
        if (mPlatformPackage == pkg) { // 平台包，包名 “android”
            // The system package is special.
            dataPath = new File (Environment.getDataDirectory(), "system");// "系统包"是特殊的，路径：data/system
            pkg.applicationInfo.dataDir = dataPath.getPath(); // 路径：data/system 目录
        } else { // 普通包
            // This is a normal package, need to make its data directory.
            dataPath = new File(mAppDataDir, pkgName);// 普通应用数据目录：data/data/"包名"
            if (dataPath.exists()) {
                mOutPermissions[1] = 0;
                FileUtils.getPermissions(dataPath.getPath(), mOutPermissions);
                if (mOutPermissions[1] == pkg.applicationInfo.uid
                        || !Process.supportsProcesses()) {
                    pkg.applicationInfo.dataDir = dataPath.getPath(); // data/data/"包名"
                } else {
                    boolean recovered = false;
                    if ((parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0) { // 如果是system app
                        // If this is a system app, we can at least delete its
                        // current data so the application will still work.
                        if (mInstaller != null) {
                            int ret = mInstaller.remove(pkgName); // 删除旧数据
                            if(ret >= 0) {
                                // Old data gone!
                                String msg = "System package " + pkg.packageName
                                        + " has changed from uid: "
                                        + mOutPermissions[1] + " to "
                                        + pkg.applicationInfo.uid + "; old data erased";
                                reportSettingsProblem(Log.WARN, msg);
                                recovered = true;
                                
                                // 重新安装
                                // And now re-install the app.
                                ret = mInstaller.install(pkgName, pkg.applicationInfo.uid,
                                        pkg.applicationInfo.uid);
                                if (ret == -1) {
                                    // Ack should not happen!
                                    msg = "System package " + 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;
                        }
                    }
                    if (!recovered) {
                        pkg.applicationInfo.dataDir = "/mismatched_uid/settings_"
                            + pkg.applicationInfo.uid + "/fs_"
                            + mOutPermissions[1];
                        String msg = "Package " + pkg.packageName
                                + " has mismatched uid: "
                                + mOutPermissions[1] + " on disk, "
                                + pkg.applicationInfo.uid + " in settings";
                        synchronized (mPackages) {
                            if (!mReportedUidError) {
                                mReportedUidError = true;
                                msg = msg + "; read messages:\n"
                                        + mSettings.getReadMessagesLP();
                            }
                            reportSettingsProblem(Log.ERROR, msg);
                        }
                    }
                }
                pkg.applicationInfo.dataDir = dataPath.getPath();
            } else {
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0 && Config.LOGV)
                    Log.v(TAG, "Want this data dir: " + dataPath);
                // 调用 installer 去执行真正的安装
                //invoke installer to do the actual installation
                if (mInstaller != null) {
                    int ret = mInstaller.install(pkgName, pkg.applicationInfo.uid,
                            pkg.applicationInfo.uid);
                    if(ret < 0) { // 安装失败，直接返回
                        // Error from installer
                        mLastScanError = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
                        return null;
                    }
                } else {
                    dataPath.mkdirs(); // 创建数据目录
                    if (dataPath.exists()) {
                        // 对数据目录设置权限
                        FileUtils.setPermissions(
                            dataPath.toString(),
                            FileUtils.S_IRWXU|FileUtils.S_IRWXG|FileUtils.S_IXOTH,
                            pkg.applicationInfo.uid, pkg.applicationInfo.uid);
                    }
                }
                if (dataPath.exists()) { // 目录创建成功，直接赋值
                    pkg.applicationInfo.dataDir = dataPath.getPath();
                } else {
                    Log.w(TAG, "Unable to create data directory: " + dataPath);
                    pkg.applicationInfo.dataDir = null;
                }
            }
        }

        // 如果不是system app，执行共享库安装和dex优化
        // Perform shared library installation and dex validation and
        // optimization, if this is not a system app.
        if (mInstaller != null) {
            String path = scanFile.getPath();
            if (scanFileNewer) {
                Log.i(TAG, path + " changed; unpacking"); // 解包
                int err = cachePackageSharedLibsLI(pkg, dataPath, scanFile);
                if (err != PackageManager.INSTALL_SUCCEEDED) {
                    mLastScanError = err;
                    return null;
                }
            }

            pkg.mForwardLocked = (scanMode&SCAN_FORWARD_LOCKED) != 0;
            pkg.mScanPath = path;
            
            if ((scanMode&SCAN_NO_DEX) == 0) {
                // 执行dex优化
                if (performDexOptLI(pkg, forceDex) == DEX_OPT_FAILED) {
                    mLastScanError = PackageManager.INSTALL_FAILED_DEXOPT;
                    return null;
                }
            }
        }
        
        // 工厂测试权限
        if (mFactoryTest && pkg.requestedPermissions.contains(
                android.Manifest.permission.FACTORY_TEST)) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_FACTORY_TEST;
        }

        // We don't expect installation to fail beyond this point,
        if ((scanMode&SCAN_MONITOR) != 0) {
            pkg.mPath = destCodeFile.getAbsolutePath();
            mAppDirs.put(pkg.mPath, pkg);
        }

        // Request the ActivityManager to kill the process(only for existing packages)
        // so that we do not end up in a confused state while the user is still using the older
        // version of the application while the new one gets installed.
        IActivityManager am = ActivityManagerNative.getDefault();
        if ((am != null) && ((parseFlags & PackageManager.INSTALL_REPLACE_EXISTING ) != 0)) {
            try {
                // 杀进程
                am.killApplicationWithUid(pkg.applicationInfo.packageName,
                        pkg.applicationInfo.uid);
            } catch (RemoteException e) {
            }
        }
        synchronized (mPackages) {
            // 添加到mSettings
            // Add the new setting to mSettings
            mSettings.insertPackageSettingLP(pkgSetting, pkg, destCodeFile, destResourceFile);
            // Add the new setting to mPackages
            // 添加到mPackages
            mPackages.put(pkg.applicationInfo.packageName, pkg);
            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);
                mProvidersByComponent.put(new ComponentName(p.info.packageName,
                        p.info.name), p);
                p.syncable = p.info.isSyncable;
                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 (!mProviders.containsKey(names[j])) {
                        mProviders.put(names[j], p);
                        if (p.info.authority == null) {
                            p.info.authority = names[j];
                        } else {
                            p.info.authority = p.info.authority + ";" + names[j];
                        }
                        if ((parseFlags&PackageParser.PARSE_CHATTY) != 0 && Config.LOGD)
                            Log.d(TAG, "Registered content provider: " + names[j] +
                            ", className = " + p.info.name +
                            ", isSyncable = " + p.info.isSyncable);
                    } else {
                        PackageParser.Provider other = mProviders.get(names[j]);
                        Log.w(TAG, "Skipping provider name " + names[j] +
                              " (in package " + pkg.applicationInfo.packageName +
                              "): name already used by "
                              + ((other != null && other.component != null)
                                      ? other.component.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 (Config.LOGD) Log.d(TAG, "  Providers: " + r);
            }
    
            N = pkg.services.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Service s = pkg.services.get(i);
                s.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        s.info.processName, pkg.applicationInfo.uid);
                mServices.addService(s);
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(s.info.name);
                }
            }
            if (r != null) {
                if (Config.LOGD) Log.d(TAG, "  Services: " + r);
            }
    
            N = pkg.receivers.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.receivers.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        a.info.processName, pkg.applicationInfo.uid);
                mReceivers.addActivity(a, "receiver");
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(a.info.name);
                }
            }
            if (r != null) {
                if (Config.LOGD) Log.d(TAG, "  Receivers: " + r);
            }
    
            N = pkg.activities.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.activities.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        a.info.processName, pkg.applicationInfo.uid);
                mActivities.addActivity(a, "activity");
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(a.info.name);
                }
            }
            if (r != null) {
                if (Config.LOGD) Log.d(TAG, "  Activities: " + r);
            }
    
            N = pkg.permissionGroups.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.PermissionGroup pg = pkg.permissionGroups.get(i);
                PackageParser.PermissionGroup cur = mPermissionGroups.get(pg.info.name);
                if (cur == null) {
                    mPermissionGroups.put(pg.info.name, pg);
                    if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                        if (r == null) {
                            r = new StringBuilder(256);
                        } else {
                            r.append(' ');
                        }
                        r.append(pg.info.name);
                    }
                } else {
                    Log.w(TAG, "Permission group " + pg.info.name + " from package "
                            + pg.info.packageName + " ignored: original from "
                            + cur.info.packageName);
                    if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                        if (r == null) {
                            r = new StringBuilder(256);
                        } else {
                            r.append(' ');
                        }
                        r.append("DUP:");
                        r.append(pg.info.name);
                    }
                }
            }
            if (r != null) {
                if (Config.LOGD) Log.d(TAG, "  Permission Groups: " + r);
            }
    
            N = pkg.permissions.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Permission p = pkg.permissions.get(i);
                HashMap<String, BasePermission> permissionMap =
                        p.tree ? mSettings.mPermissionTrees
                        : mSettings.mPermissions;
                p.group = mPermissionGroups.get(p.info.group);
                if (p.info.group == null || p.group != null) {
                    BasePermission bp = permissionMap.get(p.info.name);
                    if (bp == null) {
                        bp = new BasePermission(p.info.name, p.info.packageName,
                                BasePermission.TYPE_NORMAL);
                        permissionMap.put(p.info.name, bp);
                    }
                    if (bp.perm == null) {
                        if (bp.sourcePackage == null
                                || bp.sourcePackage.equals(p.info.packageName)) {
                            BasePermission tree = findPermissionTreeLP(p.info.name);
                            if (tree == null
                                    || tree.sourcePackage.equals(p.info.packageName)) {
                                bp.perm = p;
                                bp.uid = pkg.applicationInfo.uid;
                                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                                    if (r == null) {
                                        r = new StringBuilder(256);
                                    } else {
                                        r.append(' ');
                                    }
                                    r.append(p.info.name);
                                }
                            } else {
                                Log.w(TAG, "Permission " + p.info.name + " from package "
                                        + p.info.packageName + " ignored: base tree "
                                        + tree.name + " is from package "
                                        + tree.sourcePackage);
                            }
                        } else {
                            Log.w(TAG, "Permission " + p.info.name + " from package "
                                    + p.info.packageName + " ignored: original from "
                                    + bp.sourcePackage);
                        }
                    } else if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                        if (r == null) {
                            r = new StringBuilder(256);
                        } else {
                            r.append(' ');
                        }
                        r.append("DUP:");
                        r.append(p.info.name);
                    }
                } else {
                    Log.w(TAG, "Permission " + p.info.name + " from package "
                            + p.info.packageName + " ignored: no group "
                            + p.group);
                }
            }
            if (r != null) {
                if (Config.LOGD) Log.d(TAG, "  Permissions: " + r);
            }
    
            N = pkg.instrumentation.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Instrumentation a = pkg.instrumentation.get(i);
                a.info.packageName = pkg.applicationInfo.packageName;
                a.info.sourceDir = pkg.applicationInfo.sourceDir;
                a.info.publicSourceDir = pkg.applicationInfo.publicSourceDir;
                a.info.dataDir = pkg.applicationInfo.dataDir;
                mInstrumentation.put(a.component, a);
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(a.info.name);
                }
            }
            if (r != null) {
                if (Config.LOGD) Log.d(TAG, "  Instrumentation: " + r);
            }
    
            if (pkg.protectedBroadcasts != null) {
                N = pkg.protectedBroadcasts.size();
                for (i=0; i<N; i++) {
                    mProtectedBroadcasts.add(pkg.protectedBroadcasts.get(i));
                }
            }
            
            pkgSetting.setTimeStamp(scanFileTime);
        }
        
        return pkg;
    }