Android-6.0之PMS卸载APK

2019年4月12日 374次阅读 来源: 疾风-Bevis

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：

  1. 要卸载的apk的包名

  2. 卸载哪个用户中的该apk

  3. 是否删除code和Resources

  4. 当前所有用户

  5. 当前所有用户中该app的安装状态

  6. flags

  7. PackageRemovedInfo

  8. 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。

    原文作者：疾风-Bevis
    原文地址: https://blog.csdn.net/love000520/article/details/70462845
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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