Android-6.0之PMS卸载APK

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本文转载于：http://www.iloveandroid.net/2016/06/20/Android_PackageManagerService-2/

前面详细介绍了如何安装一个apk，现在分析PMS卸载APK的过程。

卸载一个app,要指明卸载哪个用户中的该app。卸载的过程无非就是删除沙箱目录，删除/data/app/包名,以及删除其在PMS中的相关信息，比如从PMS中去除与该app相关的组件信息等。另外也要在清除其在相关配置文件中记录，如packages.xml。

PMS卸载一个app的api是名为deletePackageAsUser的方法，刚好和installPackageAsUser()安装apk的方法相对应。

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 public void deletePackageAsUser(String packageName, IPackageDeleteObserver observer, int userId,            int flags) {        deletePackage(packageName, new LegacyPackageDeleteObserver(observer).getBinder(), userId,                flags);    }    public void deletePackage(final String packageName,            final IPackageDeleteObserver2 observer, final int userId, final int flags) {        // 同样要检查权限，看是否有权限卸载        // 主要检查卸载发起者进程是是否有权限卸载        // 当前用户是否有权限卸载        // 以及卸载的是全部用户还是当前用户        mContext.enforceCallingOrSelfPermission(                android.Manifest.permission.DELETE_PACKAGES, null);        Preconditions.checkNotNull(packageName);        Preconditions.checkNotNull(observer);        final int uid = Binder.getCallingUid();        if (UserHandle.getUserId(uid) != userId) {            mContext.enforceCallingPermission(                    android.Manifest.permission.INTERACT_ACROSS_USERS_FULL,                    "deletePackage for user " + userId);        }        if (isUserRestricted(userId, UserManager.DISALLOW_UNINSTALL_APPS)) {            try {                observer.onPackageDeleted(packageName,                        PackageManager.DELETE_FAILED_USER_RESTRICTED, null);            } catch (RemoteException re) {            }            return;        }................................................// 在消息处理方法中执行卸载应用的操作        mHandler.post(new Runnable() {            public void run() {                mHandler.removeCallbacks(this);                // 调用这个方法进行实际的卸载的操作                final int returnCode = deletePackageX(packageName, userId, flags);                if (observer != null) {                    try {                      // 发送卸载应用的结果                        observer.onPackageDeleted(packageName, returnCode, null);                    } catch (RemoteException e) {                        Log.i(TAG, "Observer no longer exists.");                    } //end catch                } //end if            } //end run        });    }

deletePackageAsUser()方法检查调用者权限之后，post了一个消息。在消息的处理方法中继续执行卸载操作，这样就避免了Binder调用时间过长。实际的卸载过程又是通过deletePackageX()方法来完成的。

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private int deletePackageX(String packageName, int userId, int flags) {    final PackageRemovedInfo info = new PackageRemovedInfo();    final boolean res;    // 卸载哪个用户下的该app    final UserHandle removeForUser = (flags & PackageManager.DELETE_ALL_USERS) != 0            ? UserHandle.ALL : new UserHandle(userId);    // 检查userid代表的用户是否由权限卸载这个应用    if (isPackageDeviceAdmin(packageName, removeForUser.getIdentifier())) {        Slog.w(TAG, "Not removing package " + packageName + ": has active device admin");        return PackageManager.DELETE_FAILED_DEVICE_POLICY_MANAGER;    }    // 是否为所有用户都卸载这个应用    boolean removedForAllUsers = false;    boolean systemUpdate = false;    // for the uninstall-updates case and restricted profiles, remember the per-    // userhandle installed state    int[] allUsers;    boolean[] perUserInstalled;    synchronized (mPackages) {      // 获取应用在mSettings中记录的信息        PackageSetting ps = mSettings.mPackages.get(packageName);        // 获取当前哪些用户安装了该app        allUsers = sUserManager.getUserIds();        perUserInstalled = new boolean[allUsers.length];        for (int i = 0; i < allUsers.length; i++) {            perUserInstalled[i] = ps != null ? ps.getInstalled(allUsers[i]) : false;        }    }    synchronized (mInstallLock) {        if (DEBUG_REMOVE) Slog.d(TAG, "deletePackageX: pkg=" + packageName + " user=" + userId);        // 调用这个方法进行卸载操作        res = deletePackageLI(packageName, removeForUser,                true, allUsers, perUserInstalled,                flags | REMOVE_CHATTY, info, true);        systemUpdate = info.isRemovedPackageSystemUpdate;        if (res && !systemUpdate && mPackages.get(packageName) == null) {            removedForAllUsers = true;        }        if (DEBUG_REMOVE) Slog.d(TAG, "delete res: systemUpdat                                      e=" + systemUpdate                + " removedForAllUsers=" + removedForAllUsers);    }    if (res) {        info.sendBroadcast(true, systemUpdate, removedForAllUsers);      //如果卸载的应用是某个系统应用的升级包，卸载它，将导致低版本的系统应用重新使用，因此发送下面的广播通知这种变化。        if (systemUpdate) {            Bundle extras = new Bundle(1);            extras.putInt(Intent.EXTRA_UID, info.removedAppId >= 0                    ? info.removedAppId : info.uid);            extras.putBoolean(Intent.EXTRA_REPLACING, true);            sendPackageBroadcast(Intent.ACTION_PACKAGE_ADDED, packageName,                    extras, null, null, null);            sendPackageBroadcast(Intent.ACTION_PACKAGE_REPLACED, packageName,                    extras, null, null, null);            sendPackageBroadcast(Intent.ACTION_MY_PACKAGE_REPLACED, null,                    null, packageName, null, null);        }    }    // Force a gc here.    Runtime.getRuntime().gc();    // Delete the resources here after sending the broadcast to let    // other processes clean up before deleting resources.    if (info.args != null) {        synchronized (mInstallLock) {          // 调用FileInstallArgs中的该方法进行清理工作          // 保证/data/app/包名中的文件都被删除了            info.args.doPostDeleteLI(true);        }    }    return res ? PackageManager.DELETE_SUCCEEDED : PackageManager.DELETE_FAILED_INTERNAL_ERROR;}

deletePackageX()方法手机了应用在不同用户下的安装情况后，调用deletePackageLI()方法继续执行卸载删除工作。如果卸载的是某个系统应用的升级包，还要广播通知以前的低版本系统应用可以再次被使用了。

deletePackageLI方法参数：

要卸载的apk的包名
卸载哪个用户中的该apk
是否删除code和Resources
当前所有用户
当前所有用户中该app的安装状态
flags
PackageRemovedInfo
是否修改packages.xml

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/* * This method handles package deletion in general */private boolean deletePackageLI(String packageName, UserHandle user,        boolean deleteCodeAndResources, int[] allUserHandles, boolean[] perUserInstalled,        int flags, PackageRemovedInfo outInfo,        boolean writeSettings) {    if (packageName == null) {        Slog.w(TAG, "Attempt to delete null packageName.");        return false;    }    if (DEBUG_REMOVE) Slog.d(TAG, "deletePackageLI: " + packageName + " user " + user);    PackageSetting ps;    boolean dataOnly = false;    int removeUser = -1;    int appId = -1;    synchronized (mPackages) {        ps = mSettings.mPackages.get(packageName);        if (ps == null) {            Slog.w(TAG, "Package named '" + packageName + "' doesn't exist.");            return false;        }        if ((!isSystemApp(ps) || (flags&PackageManager.DELETE_SYSTEM_APP) != 0) && user != null                && user.getIdentifier() != UserHandle.USER_ALL) {            // 设置要卸载的该app的用户状态，修改该app在该用户中的相关信息，标记为卸载，另外要删除在该用户中的沙箱中的数据            if (DEBUG_REMOVE) Slog.d(TAG, "Only deleting for single user");            final int userId = user.getIdentifier();            ps.setUserState(userId,                    COMPONENT_ENABLED_STATE_DEFAULT,                    false, //installed                    true,  //stopped                    true,  //notLaunched                    false, //hidden                    null, null, null,                    false, // blockUninstall                    ps.readUserState(userId).domainVerificationStatus, 0);            if (!isSystemApp(ps)) {              // 该app被其他用户也安装了，那么就不能删除该app在/data/app/下面的东西了              // 只能删除对应用用户自己的沙箱目录                if (ps.isAnyInstalled(sUserManager.getUserIds())) {                    if (DEBUG_REMOVE) Slog.d(TAG, "Still installed by other users");                    removeUser = user.getIdentifier();                    appId = ps.appId;                    // 修改/data/users/<userid>/package-restrictions.xml                    // 将上述信息记录其中                    scheduleWritePackageRestrictionsLocked(removeUser);                } else {                  //只有一个用户安装的时候，要设置其userState中的installed为true                  // 前面将其设置为了false                    if (DEBUG_REMOVE) Slog.d(TAG, "Not installed by other users, full delete");                    ps.setInstalled(true, user.getIdentifier());                }            } else {                if (DEBUG_REMOVE) Slog.d(TAG, "Deleting system app");                removeUser = user.getIdentifier();                appId = ps.appId;                scheduleWritePackageRestrictionsLocked(removeUser);            }        }    }    // 紧紧处理的是一个用户    // 因为 USER_ALL = -1    if (removeUser >= 0) {        // From above, we determined that we are deleting this only        // for a single user.  Continue the work here.        if (DEBUG_REMOVE) Slog.d(TAG, "Updating install state for user: " + removeUser);        if (outInfo != null) {            outInfo.removedPackage = packageName;            outInfo.removedAppId = appId;            outInfo.removedUsers = new int[] {removeUser};        }        // 删除该用户中的该app的沙箱目录        mInstaller.clearUserData(ps.volumeUuid, packageName, removeUser);        removeKeystoreDataIfNeeded(removeUser, appId);        // 发送START_CLEANING_PACKAGE消息        // 处理该消息时调用startCleaningPackages()        // 该方法中会发送“android.content.pm.CLEAN_EXTERNAL_STORAGE”的intent        // com.android.defcontainer.DefaultContainerService会处理它        schedulePackageCleaning(packageName, removeUser, false);        synchronized (mPackages) {            if (clearPackagePreferredActivitiesLPw(packageName, removeUser)) {                //处理UserHandle.USER_ALL这个情况                scheduleWritePackageRestrictionsLocked(removeUser);            }            resetUserChangesToRuntimePermissionsAndFlagsLPw(ps, removeUser);        }        return true;    }    ..............................    // 处理 USER_ALL    // 也就是卸载所有用户中的该app    boolean ret = false;    if (isSystemApp(ps)) {        if (DEBUG_REMOVE) Slog.d(TAG, "Removing system package:" + ps.name);        ret = deleteSystemPackageLI(ps, allUserHandles, perUserInstalled,                flags, outInfo, writeSettings);    } else {        if (DEBUG_REMOVE) Slog.d(TAG, "Removing non-system package:" + ps.name);        // 除了删除沙箱目录，/data/app/包名等文件外，还要删除其在PMS中的的数据结构，比如注册的组件等        // 这是由其内部的removePackageLI()方法完成的        killApplication(packageName, ps.appId, "uninstall pkg");        ret = deleteInstalledPackageLI(ps, deleteCodeAndResources, flags,                allUserHandles, perUserInstalled,                outInfo, writeSettings);    }    return ret;    .......

所谓的卸载apk就是这些内容了，删除文件以及其在PMS中的相关数据结构。

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