/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License
 */

package com.android.server.am;

import static android.Manifest.permission.INTERACT_ACROSS_USERS;
import static android.Manifest.permission.INTERACT_ACROSS_USERS_FULL;
import static android.app.ActivityManager.USER_OP_ERROR_IS_SYSTEM;
import static android.app.ActivityManager.USER_OP_ERROR_RELATED_USERS_CANNOT_STOP;
import static android.app.ActivityManager.USER_OP_IS_CURRENT;
import static android.app.ActivityManager.USER_OP_SUCCESS;
import static android.content.Context.KEYGUARD_SERVICE;
import static android.os.Process.SYSTEM_UID;

import static com.android.server.am.ActivityManagerDebugConfig.DEBUG_MU;
import static com.android.server.am.ActivityManagerDebugConfig.TAG_AM;
import static com.android.server.am.ActivityManagerDebugConfig.TAG_WITH_CLASS_NAME;
import static com.android.server.am.ActivityManagerService.ALLOW_FULL_ONLY;
import static com.android.server.am.ActivityManagerService.ALLOW_NON_FULL;
import static com.android.server.am.ActivityManagerService.ALLOW_NON_FULL_IN_PROFILE;
import static com.android.server.am.ActivityManagerService.MY_PID;
import static com.android.server.am.ActivityManagerService.REPORT_USER_SWITCH_COMPLETE_MSG;
import static com.android.server.am.ActivityManagerService.REPORT_USER_SWITCH_MSG;
import static com.android.server.am.ActivityManagerService.SYSTEM_USER_CURRENT_MSG;
import static com.android.server.am.ActivityManagerService.SYSTEM_USER_START_MSG;
import static com.android.server.am.ActivityManagerService.SYSTEM_USER_UNLOCK_MSG;
import static com.android.server.am.ActivityManagerService.USER_SWITCH_TIMEOUT_MSG;
import static com.android.server.am.UserState.STATE_BOOTING;
import static com.android.server.am.UserState.STATE_RUNNING_LOCKED;
import static com.android.server.am.UserState.STATE_RUNNING_UNLOCKED;
import static com.android.server.am.UserState.STATE_RUNNING_UNLOCKING;

import android.annotation.NonNull;
import android.annotation.UserIdInt;
import android.app.ActivityManager;
import android.app.AppOpsManager;
import android.app.Dialog;
import android.app.IStopUserCallback;
import android.app.IUserSwitchObserver;
import android.app.KeyguardManager;
import android.content.Context;
import android.content.IIntentReceiver;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.UserInfo;
import android.os.BatteryStats;
import android.os.Binder;
import android.os.Build;
import android.os.Bundle;
import android.os.Debug;
import android.os.Handler;
import android.os.IBinder;
import android.os.IProgressListener;
import android.os.IRemoteCallback;
import android.os.IUserManager;
import android.os.Process;
import android.os.RemoteCallbackList;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
import android.os.UserHandle;
import android.os.UserManager;
import android.os.UserManagerInternal;
import android.os.storage.IMountService;
import android.os.storage.StorageManager;
import android.util.ArraySet;
import android.util.IntArray;
import android.util.Pair;
import android.util.Slog;
import android.util.SparseArray;
import android.util.SparseIntArray;

import com.android.internal.R;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.logging.MetricsLogger;
import com.android.internal.util.ArrayUtils;
import com.android.internal.util.Preconditions;
import com.android.internal.widget.LockPatternUtils;
import com.android.server.LocalServices;
import com.android.server.pm.UserManagerService;

import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Helper class for {@link ActivityManagerService} responsible for multi-user functionality.
 */
final class UserController {
    private static final String TAG = TAG_WITH_CLASS_NAME ? "UserController" : TAG_AM;

    // Maximum number of users we allow to be running at a time.
    static final int MAX_RUNNING_USERS = 3;

    // Amount of time we wait for observers to handle a user switch before
    // giving up on them and unfreezing the screen.
    static final int USER_SWITCH_TIMEOUT = 2 * 1000;

    private final ActivityManagerService mService;
    private final Handler mHandler;

    // Holds the current foreground user's id
    private int mCurrentUserId = UserHandle.USER_SYSTEM;
    // Holds the target user's id during a user switch
    private int mTargetUserId = UserHandle.USER_NULL;

    /**
     * Which users have been started, so are allowed to run code.
     */
    @GuardedBy("mService")
    private final SparseArray<UserState> mStartedUsers = new SparseArray<>();

    /**
     * LRU list of history of current users.  Most recently current is at the end.
     */
    private final ArrayList<Integer> mUserLru = new ArrayList<>();

    /**
     * Constant array of the users that are currently started.
     */
    private int[] mStartedUserArray = new int[] { 0 };

    // If there are multiple profiles for the current user, their ids are here
    // Currently only the primary user can have managed profiles
    private int[] mCurrentProfileIds = new int[] {};

    /**
     * Mapping from each known user ID to the profile group ID it is associated with.
     */
    private final SparseIntArray mUserProfileGroupIdsSelfLocked = new SparseIntArray();

    /**
     * Registered observers of the user switching mechanics.
     */
    private final RemoteCallbackList<IUserSwitchObserver> mUserSwitchObservers
            = new RemoteCallbackList<>();

    /**
     * Currently active user switch callbacks.
     */
    private volatile ArraySet<String> mCurWaitingUserSwitchCallbacks;

    private volatile UserManagerService mUserManager;

    private final LockPatternUtils mLockPatternUtils;

    private UserManagerInternal mUserManagerInternal;

    UserController(ActivityManagerService service) {
        mService = service;
        mHandler = mService.mHandler;
        // User 0 is the first and only user that runs at boot.
        final UserState uss = new UserState(UserHandle.SYSTEM);
        mStartedUsers.put(UserHandle.USER_SYSTEM, uss);
        mUserLru.add(UserHandle.USER_SYSTEM);
        mLockPatternUtils = new LockPatternUtils(mService.mContext);
        updateStartedUserArrayLocked();
    }

    void finishUserSwitch(UserState uss) {
        synchronized (mService) {
            finishUserBoot(uss);

            startProfilesLocked();
            stopRunningUsersLocked(MAX_RUNNING_USERS);
        }
    }

    void stopRunningUsersLocked(int maxRunningUsers) {
        int num = mUserLru.size();
        int i = 0;
        while (num > maxRunningUsers && i < mUserLru.size()) {
            Integer oldUserId = mUserLru.get(i);
            UserState oldUss = mStartedUsers.get(oldUserId);
            if (oldUss == null) {
                // Shouldn't happen, but be sane if it does.
                mUserLru.remove(i);
                num--;
                continue;
            }
            if (oldUss.state == UserState.STATE_STOPPING
                    || oldUss.state == UserState.STATE_SHUTDOWN) {
                // This user is already stopping, doesn't count.
                num--;
                i++;
                continue;
            }
            if (oldUserId == UserHandle.USER_SYSTEM || oldUserId == mCurrentUserId) {
                // Owner/System user and current user can't be stopped. We count it as running
                // when it is not a pure system user.
                if (UserInfo.isSystemOnly(oldUserId)) {
                    num--;
                }
                i++;
                continue;
            }
            // This is a user to be stopped.
            if (stopUsersLocked(oldUserId, false, null) != USER_OP_SUCCESS) {
                num--;
            }
            num--;
            i++;
        }
    }

    private void finishUserBoot(UserState uss) {
        finishUserBoot(uss, null);
    }

    private void finishUserBoot(UserState uss, IIntentReceiver resultTo) {
        final int userId = uss.mHandle.getIdentifier();

        Slog.d(TAG, "Finishing user boot " + userId);
        synchronized (mService) {
            // Bail if we ended up with a stale user
            if (mStartedUsers.get(userId) != uss) return;

            // We always walk through all the user lifecycle states to send
            // consistent developer events. We step into RUNNING_LOCKED here,
            // but we might immediately step into RUNNING below if the user
            // storage is already unlocked.
            if (uss.setState(STATE_BOOTING, STATE_RUNNING_LOCKED)) {
                getUserManagerInternal().setUserState(userId, uss.state);

                int uptimeSeconds = (int)(SystemClock.elapsedRealtime() / 1000);
                MetricsLogger.histogram(mService.mContext, "framework_locked_boot_completed",
                    uptimeSeconds);

                Intent intent = new Intent(Intent.ACTION_LOCKED_BOOT_COMPLETED, null);
                intent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
                intent.addFlags(Intent.FLAG_RECEIVER_NO_ABORT
                        | Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
                mService.broadcastIntentLocked(null, null, intent, null, resultTo, 0, null, null,
                        new String[] { android.Manifest.permission.RECEIVE_BOOT_COMPLETED },
                        AppOpsManager.OP_NONE, null, true, false, MY_PID, SYSTEM_UID, userId);
            }

            // We need to delay unlocking managed profiles until the parent user
            // is also unlocked.
            if (getUserManager().isManagedProfile(userId)) {
                final UserInfo parent = getUserManager().getProfileParent(userId);
                if (parent != null
                        && isUserRunningLocked(parent.id, ActivityManager.FLAG_AND_UNLOCKED)) {
                    Slog.d(TAG, "User " + userId + " (parent " + parent.id
                            + "): attempting unlock because parent is unlocked");
                    maybeUnlockUser(userId);
                } else {
                    String parentId = (parent == null) ? "<null>" : String.valueOf(parent.id);
                    Slog.d(TAG, "User " + userId + " (parent " + parentId
                            + "): delaying unlock because parent is locked");
                }
            } else {
                maybeUnlockUser(userId);
            }
        }
    }

    /**
     * Step from {@link UserState#STATE_RUNNING_LOCKED} to
     * {@link UserState#STATE_RUNNING_UNLOCKING}.
     */
    private void finishUserUnlocking(final UserState uss) {
        final int userId = uss.mHandle.getIdentifier();
        synchronized (mService) {
            // Bail if we ended up with a stale user
            if (mStartedUsers.get(uss.mHandle.getIdentifier()) != uss) return;

            // Only keep marching forward if user is actually unlocked
            if (!StorageManager.isUserKeyUnlocked(userId)) return;

            if (uss.setState(STATE_RUNNING_LOCKED, STATE_RUNNING_UNLOCKING)) {
                getUserManagerInternal().setUserState(userId, uss.state);
                uss.mUnlockProgress.start();

                // Prepare app storage before we go any further
                uss.mUnlockProgress.setProgress(5,
                        mService.mContext.getString(R.string.android_start_title));
                mUserManager.onBeforeUnlockUser(userId);
                uss.mUnlockProgress.setProgress(20);

                // Dispatch unlocked to system services; when fully dispatched,
                // that calls through to the next "unlocked" phase
                mHandler.obtainMessage(SYSTEM_USER_UNLOCK_MSG, userId, 0, uss)
                        .sendToTarget();
            }
        }
    }

    /**
     * Step from {@link UserState#STATE_RUNNING_UNLOCKING} to
     * {@link UserState#STATE_RUNNING_UNLOCKED}.
     */
    void finishUserUnlocked(final UserState uss) {
        final int userId = uss.mHandle.getIdentifier();
        synchronized (mService) {
            // Bail if we ended up with a stale user
            if (mStartedUsers.get(uss.mHandle.getIdentifier()) != uss) return;

            // Only keep marching forward if user is actually unlocked
            if (!StorageManager.isUserKeyUnlocked(userId)) return;

            if (uss.setState(STATE_RUNNING_UNLOCKING, STATE_RUNNING_UNLOCKED)) {
                getUserManagerInternal().setUserState(userId, uss.state);
                uss.mUnlockProgress.finish();

                // Dispatch unlocked to external apps
                final Intent unlockedIntent = new Intent(Intent.ACTION_USER_UNLOCKED);
                unlockedIntent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
                unlockedIntent.addFlags(
                        Intent.FLAG_RECEIVER_REGISTERED_ONLY | Intent.FLAG_RECEIVER_FOREGROUND);
                mService.broadcastIntentLocked(null, null, unlockedIntent, null, null, 0, null,
                        null, null, AppOpsManager.OP_NONE, null, false, false, MY_PID, SYSTEM_UID,
                        userId);

                if (getUserInfo(userId).isManagedProfile()) {
                    UserInfo parent = getUserManager().getProfileParent(userId);
                    if (parent != null) {
                        final Intent profileUnlockedIntent = new Intent(
                                Intent.ACTION_MANAGED_PROFILE_UNLOCKED);
                        profileUnlockedIntent.putExtra(Intent.EXTRA_USER, UserHandle.of(userId));
                        profileUnlockedIntent.addFlags(
                                Intent.FLAG_RECEIVER_REGISTERED_ONLY
                                | Intent.FLAG_RECEIVER_FOREGROUND);
                        mService.broadcastIntentLocked(null, null, profileUnlockedIntent,
                                null, null, 0, null, null, null, AppOpsManager.OP_NONE,
                                null, false, false, MY_PID, SYSTEM_UID,
                                parent.id);
                    }
                }

                // Send PRE_BOOT broadcasts if user fingerprint changed; we
                // purposefully block sending BOOT_COMPLETED until after all
                // PRE_BOOT receivers are finished to avoid ANR'ing apps
                final UserInfo info = getUserInfo(userId);
                if (!Objects.equals(info.lastLoggedInFingerprint, Build.FINGERPRINT)) {
                    new PreBootBroadcaster(mService, userId, null) {
                        @Override
                        public void onFinished() {
                            finishUserUnlockedCompleted(uss);
                        }
                    }.sendNext();
                } else {
                    finishUserUnlockedCompleted(uss);
                }
            }
        }
    }

    private void finishUserUnlockedCompleted(UserState uss) {
        final int userId = uss.mHandle.getIdentifier();
        synchronized (mService) {
            // Bail if we ended up with a stale user
            if (mStartedUsers.get(uss.mHandle.getIdentifier()) != uss) return;
            final UserInfo userInfo = getUserInfo(userId);
            if (userInfo == null) {
                return;
            }

            // Only keep marching forward if user is actually unlocked
            if (!StorageManager.isUserKeyUnlocked(userId)) return;

            // Remember that we logged in
            mUserManager.onUserLoggedIn(userId);

            if (!userInfo.isInitialized()) {
                if (userId != UserHandle.USER_SYSTEM) {
                    Slog.d(TAG, "Initializing user #" + userId);
                    Intent intent = new Intent(Intent.ACTION_USER_INITIALIZE);
                    intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
                    mService.broadcastIntentLocked(null, null, intent, null,
                            new IIntentReceiver.Stub() {
                                @Override
                                public void performReceive(Intent intent, int resultCode,
                                        String data, Bundle extras, boolean ordered,
                                        boolean sticky, int sendingUser) {
                                    // Note: performReceive is called with mService lock held
                                    getUserManager().makeInitialized(userInfo.id);
                                }
                            }, 0, null, null, null, AppOpsManager.OP_NONE,
                            null, true, false, MY_PID, SYSTEM_UID, userId);
                }
            }

            Slog.d(TAG, "Sending BOOT_COMPLETE user #" + userId);
            int uptimeSeconds = (int)(SystemClock.elapsedRealtime() / 1000);
            MetricsLogger.histogram(mService.mContext, "framework_boot_completed", uptimeSeconds);
            final Intent bootIntent = new Intent(Intent.ACTION_BOOT_COMPLETED, null);
            bootIntent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
            bootIntent.addFlags(Intent.FLAG_RECEIVER_NO_ABORT
                    | Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND);
            mService.broadcastIntentLocked(null, null, bootIntent, null, null, 0, null, null,
                    new String[] { android.Manifest.permission.RECEIVE_BOOT_COMPLETED },
                    AppOpsManager.OP_NONE, null, true, false, MY_PID, SYSTEM_UID, userId);
        }
    }

    int stopUser(final int userId, final boolean force, final IStopUserCallback callback) {
        if (mService.checkCallingPermission(INTERACT_ACROSS_USERS_FULL)
                != PackageManager.PERMISSION_GRANTED) {
            String msg = "Permission Denial: switchUser() from pid="
                    + Binder.getCallingPid()
                    + ", uid=" + Binder.getCallingUid()
                    + " requires " + INTERACT_ACROSS_USERS_FULL;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }
        if (userId < 0 || userId == UserHandle.USER_SYSTEM) {
            throw new IllegalArgumentException("Can't stop system user " + userId);
        }
        mService.enforceShellRestriction(UserManager.DISALLOW_DEBUGGING_FEATURES,
                userId);
        synchronized (mService) {
            return stopUsersLocked(userId, force, callback);
        }
    }

    /**
     * Stops the user along with its related users. The method calls
     * {@link #getUsersToStopLocked(int)} to determine the list of users that should be stopped.
     */
    private int stopUsersLocked(final int userId, boolean force, final IStopUserCallback callback) {
        if (userId == UserHandle.USER_SYSTEM) {
            return USER_OP_ERROR_IS_SYSTEM;
        }
        if (isCurrentUserLocked(userId)) {
            return USER_OP_IS_CURRENT;
        }
        int[] usersToStop = getUsersToStopLocked(userId);
        // If one of related users is system or current, no related users should be stopped
        for (int i = 0; i < usersToStop.length; i++) {
            int relatedUserId = usersToStop[i];
            if ((UserHandle.USER_SYSTEM == relatedUserId) || isCurrentUserLocked(relatedUserId)) {
                if (DEBUG_MU) Slog.i(TAG, "stopUsersLocked cannot stop related user "
                        + relatedUserId);
                // We still need to stop the requested user if it's a force stop.
                if (force) {
                    Slog.i(TAG,
                            "Force stop user " + userId + ". Related users will not be stopped");
                    stopSingleUserLocked(userId, callback);
                    return USER_OP_SUCCESS;
                }
                return USER_OP_ERROR_RELATED_USERS_CANNOT_STOP;
            }
        }
        if (DEBUG_MU) Slog.i(TAG, "stopUsersLocked usersToStop=" + Arrays.toString(usersToStop));
        for (int userIdToStop : usersToStop) {
            stopSingleUserLocked(userIdToStop, userIdToStop == userId ? callback : null);
        }
        return USER_OP_SUCCESS;
    }

    private void stopSingleUserLocked(final int userId, final IStopUserCallback callback) {
        if (DEBUG_MU) Slog.i(TAG, "stopSingleUserLocked userId=" + userId);
        final UserState uss = mStartedUsers.get(userId);
        if (uss == null) {
            // User is not started, nothing to do...  but we do need to
            // callback if requested.
            if (callback != null) {
                mHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            callback.userStopped(userId);
                        } catch (RemoteException e) {
                        }
                    }
                });
            }
            return;
        }

        if (callback != null) {
            uss.mStopCallbacks.add(callback);
        }

        if (uss.state != UserState.STATE_STOPPING
                && uss.state != UserState.STATE_SHUTDOWN) {
            uss.setState(UserState.STATE_STOPPING);
            getUserManagerInternal().setUserState(userId, uss.state);
            updateStartedUserArrayLocked();

            long ident = Binder.clearCallingIdentity();
            try {
                // We are going to broadcast ACTION_USER_STOPPING and then
                // once that is done send a final ACTION_SHUTDOWN and then
                // stop the user.
                final Intent stoppingIntent = new Intent(Intent.ACTION_USER_STOPPING);
                stoppingIntent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
                stoppingIntent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
                stoppingIntent.putExtra(Intent.EXTRA_SHUTDOWN_USERSPACE_ONLY, true);
                // This is the result receiver for the initial stopping broadcast.
                final IIntentReceiver stoppingReceiver = new IIntentReceiver.Stub() {
                    @Override
                    public void performReceive(Intent intent, int resultCode, String data,
                            Bundle extras, boolean ordered, boolean sticky, int sendingUser) {
                        mHandler.post(new Runnable() {
                            @Override
                            public void run() {
                                finishUserStopping(userId, uss);
                            }
                        });
                    }
                };
                // Clear broadcast queue for the user to avoid delivering stale broadcasts
                mService.clearBroadcastQueueForUserLocked(userId);
                // Kick things off.
                mService.broadcastIntentLocked(null, null, stoppingIntent,
                        null, stoppingReceiver, 0, null, null,
                        new String[]{INTERACT_ACROSS_USERS}, AppOpsManager.OP_NONE,
                        null, true, false, MY_PID, SYSTEM_UID, UserHandle.USER_ALL);
            } finally {
                Binder.restoreCallingIdentity(ident);
            }
        }
    }

    void finishUserStopping(final int userId, final UserState uss) {
        // On to the next.
        final Intent shutdownIntent = new Intent(Intent.ACTION_SHUTDOWN);
        // This is the result receiver for the final shutdown broadcast.
        final IIntentReceiver shutdownReceiver = new IIntentReceiver.Stub() {
            @Override
            public void performReceive(Intent intent, int resultCode, String data,
                    Bundle extras, boolean ordered, boolean sticky, int sendingUser) {
                mHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        finishUserStopped(uss);
                    }
                });
            }
        };

        synchronized (mService) {
            if (uss.state != UserState.STATE_STOPPING) {
                // Whoops, we are being started back up.  Abort, abort!
                return;
            }
            uss.setState(UserState.STATE_SHUTDOWN);
        }
        getUserManagerInternal().setUserState(userId, uss.state);

        mService.mBatteryStatsService.noteEvent(
                BatteryStats.HistoryItem.EVENT_USER_RUNNING_FINISH,
                Integer.toString(userId), userId);
        mService.mSystemServiceManager.stopUser(userId);

        synchronized (mService) {
            mService.broadcastIntentLocked(null, null, shutdownIntent,
                    null, shutdownReceiver, 0, null, null, null,
                    AppOpsManager.OP_NONE,
                    null, true, false, MY_PID, SYSTEM_UID, userId);
        }
    }

    void finishUserStopped(UserState uss) {
        final int userId = uss.mHandle.getIdentifier();
        boolean stopped;
        ArrayList<IStopUserCallback> callbacks;
        synchronized (mService) {
            callbacks = new ArrayList<>(uss.mStopCallbacks);
            if (mStartedUsers.get(userId) != uss) {
                stopped = false;
            } else if (uss.state != UserState.STATE_SHUTDOWN) {
                stopped = false;
            } else {
                stopped = true;
                // User can no longer run.
                mStartedUsers.remove(userId);
                getUserManagerInternal().removeUserState(userId);
                mUserLru.remove(Integer.valueOf(userId));
                updateStartedUserArrayLocked();

                mService.onUserStoppedLocked(userId);
                // Clean up all state and processes associated with the user.
                // Kill all the processes for the user.
                forceStopUserLocked(userId, "finish user");
            }
        }

        for (int i = 0; i < callbacks.size(); i++) {
            try {
                if (stopped) callbacks.get(i).userStopped(userId);
                else callbacks.get(i).userStopAborted(userId);
            } catch (RemoteException e) {
            }
        }

        if (stopped) {
            mService.mSystemServiceManager.cleanupUser(userId);
            synchronized (mService) {
                mService.mStackSupervisor.removeUserLocked(userId);
            }
            // Remove the user if it is ephemeral.
            if (getUserInfo(userId).isEphemeral()) {
                mUserManager.removeUser(userId);
            }
        }
    }

    /**
     * Determines the list of users that should be stopped together with the specified
     * {@code userId}. The returned list includes {@code userId}.
     */
    private @NonNull int[] getUsersToStopLocked(int userId) {
        int startedUsersSize = mStartedUsers.size();
        IntArray userIds = new IntArray();
        userIds.add(userId);
        synchronized (mUserProfileGroupIdsSelfLocked) {
            int userGroupId = mUserProfileGroupIdsSelfLocked.get(userId,
                    UserInfo.NO_PROFILE_GROUP_ID);
            for (int i = 0; i < startedUsersSize; i++) {
                UserState uss = mStartedUsers.valueAt(i);
                int startedUserId = uss.mHandle.getIdentifier();
                // Skip unrelated users (profileGroupId mismatch)
                int startedUserGroupId = mUserProfileGroupIdsSelfLocked.get(startedUserId,
                        UserInfo.NO_PROFILE_GROUP_ID);
                boolean sameGroup = (userGroupId != UserInfo.NO_PROFILE_GROUP_ID)
                        && (userGroupId == startedUserGroupId);
                // userId has already been added
                boolean sameUserId = startedUserId == userId;
                if (!sameGroup || sameUserId) {
                    continue;
                }
                userIds.add(startedUserId);
            }
        }
        return userIds.toArray();
    }

    private void forceStopUserLocked(int userId, String reason) {
        mService.forceStopPackageLocked(null, -1, false, false, true, false, false,
                userId, reason);
        Intent intent = new Intent(Intent.ACTION_USER_STOPPED);
        intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
                | Intent.FLAG_RECEIVER_FOREGROUND);
        intent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
        mService.broadcastIntentLocked(null, null, intent,
                null, null, 0, null, null, null, AppOpsManager.OP_NONE,
                null, false, false, MY_PID, SYSTEM_UID, UserHandle.USER_ALL);
    }

    /**
     * Stops the guest or ephemeral user if it has gone to the background.
     */
    private void stopGuestOrEphemeralUserIfBackground() {
        synchronized (mService) {
            final int num = mUserLru.size();
            for (int i = 0; i < num; i++) {
                Integer oldUserId = mUserLru.get(i);
                UserState oldUss = mStartedUsers.get(oldUserId);
                if (oldUserId == UserHandle.USER_SYSTEM || oldUserId == mCurrentUserId
                        || oldUss.state == UserState.STATE_STOPPING
                        || oldUss.state == UserState.STATE_SHUTDOWN) {
                    continue;
                }
                UserInfo userInfo = getUserInfo(oldUserId);
                if (userInfo.isEphemeral()) {
                    LocalServices.getService(UserManagerInternal.class)
                            .onEphemeralUserStop(oldUserId);
                }
                if (userInfo.isGuest() || userInfo.isEphemeral()) {
                    // This is a user to be stopped.
                    stopUsersLocked(oldUserId, true, null);
                    break;
                }
            }
        }
    }

    void startProfilesLocked() {
        if (DEBUG_MU) Slog.i(TAG, "startProfilesLocked");
        List<UserInfo> profiles = getUserManager().getProfiles(
                mCurrentUserId, false /* enabledOnly */);
        List<UserInfo> profilesToStart = new ArrayList<>(profiles.size());
        for (UserInfo user : profiles) {
            if ((user.flags & UserInfo.FLAG_INITIALIZED) == UserInfo.FLAG_INITIALIZED
                    && user.id != mCurrentUserId && !user.isQuietModeEnabled()) {
                profilesToStart.add(user);
            }
        }
        final int profilesToStartSize = profilesToStart.size();
        int i = 0;
        for (; i < profilesToStartSize && i < (MAX_RUNNING_USERS - 1); ++i) {
            startUser(profilesToStart.get(i).id, /* foreground= */ false);
        }
        if (i < profilesToStartSize) {
            Slog.w(TAG, "More profiles than MAX_RUNNING_USERS");
        }
    }

    private UserManagerService getUserManager() {
        UserManagerService userManager = mUserManager;
        if (userManager == null) {
            IBinder b = ServiceManager.getService(Context.USER_SERVICE);
            userManager = mUserManager = (UserManagerService) IUserManager.Stub.asInterface(b);
        }
        return userManager;
    }

    private IMountService getMountService() {
        return IMountService.Stub.asInterface(ServiceManager.getService("mount"));
    }

    /**
     * Start user, if its not already running.
     * <p>The user will be brought to the foreground, if {@code foreground} parameter is set.
     * When starting the user, multiple intents will be broadcast in the following order:</p>
     * <ul>
     *     <li>{@link Intent#ACTION_USER_STARTED} - sent to registered receivers of the new user
     *     <li>{@link Intent#ACTION_USER_BACKGROUND} - sent to registered receivers of the outgoing
     *     user and all profiles of this user. Sent only if {@code foreground} parameter is true
     *     <li>{@link Intent#ACTION_USER_FOREGROUND} - sent to registered receivers of the new
     *     user and all profiles of this user. Sent only if {@code foreground} parameter is true
     *     <li>{@link Intent#ACTION_USER_SWITCHED} - sent to registered receivers of the new user.
     *     Sent only if {@code foreground} parameter is true
     *     <li>{@link Intent#ACTION_USER_STARTING} - ordered broadcast sent to registered receivers
     *     of the new fg user
     *     <li>{@link Intent#ACTION_LOCKED_BOOT_COMPLETED} - ordered broadcast sent to receivers of
     *     the new user
     *     <li>{@link Intent#ACTION_USER_UNLOCKED} - sent to registered receivers of the new user
     *     <li>{@link Intent#ACTION_PRE_BOOT_COMPLETED} - ordered broadcast sent to receivers of the
     *     new user. Sent only when the user is booting after a system update.
     *     <li>{@link Intent#ACTION_USER_INITIALIZE} - ordered broadcast sent to receivers of the
     *     new user. Sent only the first time a user is starting.
     *     <li>{@link Intent#ACTION_BOOT_COMPLETED} - ordered broadcast sent to receivers of the new
     *     user. Indicates that the user has finished booting.
     * </ul>
     *
     * @param userId ID of the user to start
     * @param foreground true if user should be brought to the foreground
     * @return true if the user has been successfully started
     */
    boolean startUser(final int userId, final boolean foreground) {
        if (mService.checkCallingPermission(INTERACT_ACROSS_USERS_FULL)
                != PackageManager.PERMISSION_GRANTED) {
            String msg = "Permission Denial: switchUser() from pid="
                    + Binder.getCallingPid()
                    + ", uid=" + Binder.getCallingUid()
                    + " requires " + INTERACT_ACROSS_USERS_FULL;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }

        Slog.i(TAG, "Starting userid:" + userId + " fg:" + foreground);

        final long ident = Binder.clearCallingIdentity();
        try {
            synchronized (mService) {
                final int oldUserId = mCurrentUserId;
                if (oldUserId == userId) {
                    return true;
                }

                mService.mStackSupervisor.setLockTaskModeLocked(null,
                        ActivityManager.LOCK_TASK_MODE_NONE, "startUser", false);

                final UserInfo userInfo = getUserInfo(userId);
                if (userInfo == null) {
                    Slog.w(TAG, "No user info for user #" + userId);
                    return false;
                }
                if (foreground && userInfo.isManagedProfile()) {
                    Slog.w(TAG, "Cannot switch to User #" + userId + ": not a full user");
                    return false;
                }

                if (foreground) {
                    mService.mWindowManager.startFreezingScreen(
                            R.anim.screen_user_exit, R.anim.screen_user_enter);
                }

                boolean needStart = false;

                // If the user we are switching to is not currently started, then
                // we need to start it now.
                if (mStartedUsers.get(userId) == null) {
                    UserState userState = new UserState(UserHandle.of(userId));
                    mStartedUsers.put(userId, userState);
                    getUserManagerInternal().setUserState(userId, userState.state);
                    updateStartedUserArrayLocked();
                    needStart = true;
                }

                final UserState uss = mStartedUsers.get(userId);
                final Integer userIdInt = userId;
                mUserLru.remove(userIdInt);
                mUserLru.add(userIdInt);

                if (foreground) {
                    mCurrentUserId = userId;
                    mService.updateUserConfigurationLocked();
                    mTargetUserId = UserHandle.USER_NULL; // reset, mCurrentUserId has caught up
                    updateCurrentProfileIdsLocked();
                    mService.mWindowManager.setCurrentUser(userId, mCurrentProfileIds);
                    // Once the internal notion of the active user has switched, we lock the device
                    // with the option to show the user switcher on the keyguard.
                    mService.mWindowManager.lockNow(null);
                } else {
                    final Integer currentUserIdInt = mCurrentUserId;
                    updateCurrentProfileIdsLocked();
                    mService.mWindowManager.setCurrentProfileIds(mCurrentProfileIds);
                    mUserLru.remove(currentUserIdInt);
                    mUserLru.add(currentUserIdInt);
                }

                // Make sure user is in the started state.  If it is currently
                // stopping, we need to knock that off.
                if (uss.state == UserState.STATE_STOPPING) {
                    // If we are stopping, we haven't sent ACTION_SHUTDOWN,
                    // so we can just fairly silently bring the user back from
                    // the almost-dead.
                    uss.setState(uss.lastState);
                    getUserManagerInternal().setUserState(userId, uss.state);
                    updateStartedUserArrayLocked();
                    needStart = true;
                } else if (uss.state == UserState.STATE_SHUTDOWN) {
                    // This means ACTION_SHUTDOWN has been sent, so we will
                    // need to treat this as a new boot of the user.
                    uss.setState(UserState.STATE_BOOTING);
                    getUserManagerInternal().setUserState(userId, uss.state);
                    updateStartedUserArrayLocked();
                    needStart = true;
                }

                if (uss.state == UserState.STATE_BOOTING) {
                    // Give user manager a chance to propagate user restrictions
                    // to other services and prepare app storage
                    getUserManager().onBeforeStartUser(userId);

                    // Booting up a new user, need to tell system services about it.
                    // Note that this is on the same handler as scheduling of broadcasts,
                    // which is important because it needs to go first.
                    mHandler.sendMessage(mHandler.obtainMessage(SYSTEM_USER_START_MSG, userId, 0));
                }

                if (foreground) {
                    mHandler.sendMessage(mHandler.obtainMessage(SYSTEM_USER_CURRENT_MSG, userId,
                            oldUserId));
                    mHandler.removeMessages(REPORT_USER_SWITCH_MSG);
                    mHandler.removeMessages(USER_SWITCH_TIMEOUT_MSG);
                    mHandler.sendMessage(mHandler.obtainMessage(REPORT_USER_SWITCH_MSG,
                            oldUserId, userId, uss));
                    mHandler.sendMessageDelayed(mHandler.obtainMessage(USER_SWITCH_TIMEOUT_MSG,
                            oldUserId, userId, uss), USER_SWITCH_TIMEOUT);
                }

                if (needStart) {
                    // Send USER_STARTED broadcast
                    Intent intent = new Intent(Intent.ACTION_USER_STARTED);
                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
                            | Intent.FLAG_RECEIVER_FOREGROUND);
                    intent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
                    mService.broadcastIntentLocked(null, null, intent,
                            null, null, 0, null, null, null, AppOpsManager.OP_NONE,
                            null, false, false, MY_PID, SYSTEM_UID, userId);
                }

                if (foreground) {
                    moveUserToForegroundLocked(uss, oldUserId, userId);
                } else {
                    mService.mUserController.finishUserBoot(uss);
                }

                if (needStart) {
                    Intent intent = new Intent(Intent.ACTION_USER_STARTING);
                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
                    intent.putExtra(Intent.EXTRA_USER_HANDLE, userId);
                    mService.broadcastIntentLocked(null, null, intent,
                            null, new IIntentReceiver.Stub() {
                                @Override
                                public void performReceive(Intent intent, int resultCode,
                                        String data, Bundle extras, boolean ordered, boolean sticky,
                                        int sendingUser) throws RemoteException {
                                }
                            }, 0, null, null,
                            new String[] {INTERACT_ACROSS_USERS}, AppOpsManager.OP_NONE,
                            null, true, false, MY_PID, SYSTEM_UID, UserHandle.USER_ALL);
                }
            }
        } finally {
            Binder.restoreCallingIdentity(ident);
        }

        return true;
    }

    /**
     * Start user, if its not already running, and bring it to foreground.
     */
    boolean startUserInForeground(final int userId, Dialog dlg) {
        boolean result = startUser(userId, /* foreground */ true);
        dlg.dismiss();
        return result;
    }

    boolean unlockUser(final int userId, byte[] token, byte[] secret, IProgressListener listener) {
        if (mService.checkCallingPermission(INTERACT_ACROSS_USERS_FULL)
                != PackageManager.PERMISSION_GRANTED) {
            String msg = "Permission Denial: unlockUser() from pid="
                    + Binder.getCallingPid()
                    + ", uid=" + Binder.getCallingUid()
                    + " requires " + INTERACT_ACROSS_USERS_FULL;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }

        final long binderToken = Binder.clearCallingIdentity();
        try {
            return unlockUserCleared(userId, token, secret, listener);
        } finally {
            Binder.restoreCallingIdentity(binderToken);
        }
    }

    /**
     * Attempt to unlock user without a credential token. This typically
     * succeeds when the device doesn't have credential-encrypted storage, or
     * when the the credential-encrypted storage isn't tied to a user-provided
     * PIN or pattern.
     */
    boolean maybeUnlockUser(final int userId) {
        // Try unlocking storage using empty token
        return unlockUserCleared(userId, null, null, null);
    }

    private static void notifyFinished(int userId, IProgressListener listener) {
        if (listener == null) return;
        try {
            listener.onFinished(userId, null);
        } catch (RemoteException ignored) {
        }
    }

    boolean unlockUserCleared(final int userId, byte[] token, byte[] secret,
            IProgressListener listener) {
        synchronized (mService) {
            // TODO Move this block outside of synchronized if it causes lock contention
            if (!StorageManager.isUserKeyUnlocked(userId)) {
                final UserInfo userInfo = getUserInfo(userId);
                final IMountService mountService = getMountService();
                try {
                    // We always want to unlock user storage, even user is not started yet
                    mountService.unlockUserKey(userId, userInfo.serialNumber, token, secret);
                } catch (RemoteException | RuntimeException e) {
                    Slog.w(TAG, "Failed to unlock: " + e.getMessage());
                }
            }
            // Bail if user isn't actually running, otherwise register the given
            // listener to watch for unlock progress
            final UserState uss = mStartedUsers.get(userId);
            if (uss == null) {
                notifyFinished(userId, listener);
                return false;
            } else {
                uss.mUnlockProgress.addListener(listener);
            }

            finishUserUnlocking(uss);

            // We just unlocked a user, so let's now attempt to unlock any
            // managed profiles under that user.
            for (int i = 0; i < mStartedUsers.size(); i++) {
                final int testUserId = mStartedUsers.keyAt(i);
                final UserInfo parent = getUserManager().getProfileParent(testUserId);
                if (parent != null && parent.id == userId && testUserId != userId) {
                    Slog.d(TAG, "User " + testUserId + " (parent " + parent.id
                            + "): attempting unlock because parent was just unlocked");
                    maybeUnlockUser(testUserId);
                }
            }
        }

        return true;
    }

    void showUserSwitchDialog(Pair<UserInfo, UserInfo> fromToUserPair) {
        // The dialog will show and then initiate the user switch by calling startUserInForeground
        Dialog d = new UserSwitchingDialog(mService, mService.mContext, fromToUserPair.first,
                fromToUserPair.second, true /* above system */);
        d.show();
    }

    void dispatchForegroundProfileChanged(int userId) {
        final int observerCount = mUserSwitchObservers.beginBroadcast();
        for (int i = 0; i < observerCount; i++) {
            try {
                mUserSwitchObservers.getBroadcastItem(i).onForegroundProfileSwitch(userId);
            } catch (RemoteException e) {
                // Ignore
            }
        }
        mUserSwitchObservers.finishBroadcast();
    }

    /** Called on handler thread */
    void dispatchUserSwitchComplete(int userId) {
        final int observerCount = mUserSwitchObservers.beginBroadcast();
        for (int i = 0; i < observerCount; i++) {
            try {
                mUserSwitchObservers.getBroadcastItem(i).onUserSwitchComplete(userId);
            } catch (RemoteException e) {
            }
        }
        mUserSwitchObservers.finishBroadcast();
    }

    private void stopBackgroundUsersIfEnforced(int oldUserId) {
        // Never stop system user
        if (oldUserId == UserHandle.USER_SYSTEM) {
            return;
        }
        // For now, only check for user restriction. Additional checks can be added here
        boolean disallowRunInBg = hasUserRestriction(UserManager.DISALLOW_RUN_IN_BACKGROUND,
                oldUserId);
        if (!disallowRunInBg) {
            return;
        }
        synchronized (mService) {
            if (DEBUG_MU) Slog.i(TAG, "stopBackgroundUsersIfEnforced stopping " + oldUserId
                    + " and related users");
            stopUsersLocked(oldUserId, false, null);
        }
    }

    void timeoutUserSwitch(UserState uss, int oldUserId, int newUserId) {
        synchronized (mService) {
            Slog.wtf(TAG, "User switch timeout: from " + oldUserId + " to " + newUserId
                    + ". Observers that didn't send results: " + mCurWaitingUserSwitchCallbacks);
            sendContinueUserSwitchLocked(uss, oldUserId, newUserId);
        }
    }

    void dispatchUserSwitch(final UserState uss, final int oldUserId, final int newUserId) {
        Slog.d(TAG, "Dispatch onUserSwitching oldUser #" + oldUserId + " newUser #" + newUserId);
        final int observerCount = mUserSwitchObservers.beginBroadcast();
        if (observerCount > 0) {
            final ArraySet<String> curWaitingUserSwitchCallbacks = new ArraySet<>();
            synchronized (mService) {
                uss.switching = true;
                mCurWaitingUserSwitchCallbacks = curWaitingUserSwitchCallbacks;
            }
            final AtomicInteger waitingCallbacksCount = new AtomicInteger(observerCount);
            for (int i = 0; i < observerCount; i++) {
                try {
                    // Prepend with unique prefix to guarantee that keys are unique
                    final String name = "#" + i + " " + mUserSwitchObservers.getBroadcastCookie(i);
                    synchronized (mService) {
                        curWaitingUserSwitchCallbacks.add(name);
                    }
                    final IRemoteCallback callback = new IRemoteCallback.Stub() {
                        @Override
                        public void sendResult(Bundle data) throws RemoteException {
                            synchronized (mService) {
                                // Early return if this session is no longer valid
                                if (curWaitingUserSwitchCallbacks
                                        != mCurWaitingUserSwitchCallbacks) {
                                    return;
                                }
                                curWaitingUserSwitchCallbacks.remove(name);
                                // Continue switching if all callbacks have been notified
                                if (waitingCallbacksCount.decrementAndGet() == 0) {
                                    sendContinueUserSwitchLocked(uss, oldUserId, newUserId);
                                }
                            }
                        }
                    };
                    mUserSwitchObservers.getBroadcastItem(i).onUserSwitching(newUserId, callback);
                } catch (RemoteException e) {
                }
            }
        } else {
            synchronized (mService) {
                sendContinueUserSwitchLocked(uss, oldUserId, newUserId);
            }
        }
        mUserSwitchObservers.finishBroadcast();
    }

    void sendContinueUserSwitchLocked(UserState uss, int oldUserId, int newUserId) {
        mCurWaitingUserSwitchCallbacks = null;
        mHandler.removeMessages(USER_SWITCH_TIMEOUT_MSG);
        mHandler.sendMessage(mHandler.obtainMessage(ActivityManagerService.CONTINUE_USER_SWITCH_MSG,
                oldUserId, newUserId, uss));
    }

    void continueUserSwitch(UserState uss, int oldUserId, int newUserId) {
        Slog.d(TAG, "Continue user switch oldUser #" + oldUserId + ", newUser #" + newUserId);
        synchronized (mService) {
            mService.mWindowManager.stopFreezingScreen();
        }
        uss.switching = false;
        mHandler.removeMessages(REPORT_USER_SWITCH_COMPLETE_MSG);
        mHandler.sendMessage(mHandler.obtainMessage(REPORT_USER_SWITCH_COMPLETE_MSG,
                newUserId, 0));
        stopGuestOrEphemeralUserIfBackground();
        stopBackgroundUsersIfEnforced(oldUserId);
    }

    void moveUserToForegroundLocked(UserState uss, int oldUserId, int newUserId) {
        boolean homeInFront = mService.mStackSupervisor.switchUserLocked(newUserId, uss);
        if (homeInFront) {
            mService.startHomeActivityLocked(newUserId, "moveUserToForeground");
        } else {
            mService.mStackSupervisor.resumeFocusedStackTopActivityLocked();
        }
        EventLogTags.writeAmSwitchUser(newUserId);
        sendUserSwitchBroadcastsLocked(oldUserId, newUserId);
    }

    void sendUserSwitchBroadcastsLocked(int oldUserId, int newUserId) {
        long ident = Binder.clearCallingIdentity();
        try {
            Intent intent;
            if (oldUserId >= 0) {
                // Send USER_BACKGROUND broadcast to all profiles of the outgoing user
                List<UserInfo> profiles = getUserManager().getProfiles(oldUserId, false);
                int count = profiles.size();
                for (int i = 0; i < count; i++) {
                    int profileUserId = profiles.get(i).id;
                    intent = new Intent(Intent.ACTION_USER_BACKGROUND);
                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
                            | Intent.FLAG_RECEIVER_FOREGROUND);
                    intent.putExtra(Intent.EXTRA_USER_HANDLE, profileUserId);
                    mService.broadcastIntentLocked(null, null, intent,
                            null, null, 0, null, null, null, AppOpsManager.OP_NONE,
                            null, false, false, MY_PID, SYSTEM_UID, profileUserId);
                }
            }
            if (newUserId >= 0) {
                // Send USER_FOREGROUND broadcast to all profiles of the incoming user
                List<UserInfo> profiles = getUserManager().getProfiles(newUserId, false);
                int count = profiles.size();
                for (int i = 0; i < count; i++) {
                    int profileUserId = profiles.get(i).id;
                    intent = new Intent(Intent.ACTION_USER_FOREGROUND);
                    intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
                            | Intent.FLAG_RECEIVER_FOREGROUND);
                    intent.putExtra(Intent.EXTRA_USER_HANDLE, profileUserId);
                    mService.broadcastIntentLocked(null, null, intent,
                            null, null, 0, null, null, null, AppOpsManager.OP_NONE,
                            null, false, false, MY_PID, SYSTEM_UID, profileUserId);
                }
                intent = new Intent(Intent.ACTION_USER_SWITCHED);
                intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
                        | Intent.FLAG_RECEIVER_FOREGROUND);
                intent.putExtra(Intent.EXTRA_USER_HANDLE, newUserId);
                mService.broadcastIntentLocked(null, null, intent,
                        null, null, 0, null, null,
                        new String[] {android.Manifest.permission.MANAGE_USERS},
                        AppOpsManager.OP_NONE, null, false, false, MY_PID, SYSTEM_UID,
                        UserHandle.USER_ALL);
            }
        } finally {
            Binder.restoreCallingIdentity(ident);
        }
    }


    int handleIncomingUser(int callingPid, int callingUid, int userId, boolean allowAll,
            int allowMode, String name, String callerPackage) {
        final int callingUserId = UserHandle.getUserId(callingUid);
        if (callingUserId == userId) {
            return userId;
        }

        // Note that we may be accessing mCurrentUserId outside of a lock...
        // shouldn't be a big deal, if this is being called outside
        // of a locked context there is intrinsically a race with
        // the value the caller will receive and someone else changing it.
        // We assume that USER_CURRENT_OR_SELF will use the current user; later
        // we will switch to the calling user if access to the current user fails.
        int targetUserId = unsafeConvertIncomingUserLocked(userId);

        if (callingUid != 0 && callingUid != SYSTEM_UID) {
            final boolean allow;
            if (mService.checkComponentPermission(INTERACT_ACROSS_USERS_FULL, callingPid,
                    callingUid, -1, true) == PackageManager.PERMISSION_GRANTED) {
                // If the caller has this permission, they always pass go.  And collect $200.
                allow = true;
            } else if (allowMode == ALLOW_FULL_ONLY) {
                // We require full access, sucks to be you.
                allow = false;
            } else if (mService.checkComponentPermission(INTERACT_ACROSS_USERS, callingPid,
                    callingUid, -1, true) != PackageManager.PERMISSION_GRANTED) {
                // If the caller does not have either permission, they are always doomed.
                allow = false;
            } else if (allowMode == ALLOW_NON_FULL) {
                // We are blanket allowing non-full access, you lucky caller!
                allow = true;
            } else if (allowMode == ALLOW_NON_FULL_IN_PROFILE) {
                // We may or may not allow this depending on whether the two users are
                // in the same profile.
                allow = isSameProfileGroup(callingUserId, targetUserId);
            } else {
                throw new IllegalArgumentException("Unknown mode: " + allowMode);
            }
            if (!allow) {
                if (userId == UserHandle.USER_CURRENT_OR_SELF) {
                    // In this case, they would like to just execute as their
                    // owner user instead of failing.
                    targetUserId = callingUserId;
                } else {
                    StringBuilder builder = new StringBuilder(128);
                    builder.append("Permission Denial: ");
                    builder.append(name);
                    if (callerPackage != null) {
                        builder.append(" from ");
                        builder.append(callerPackage);
                    }
                    builder.append(" asks to run as user ");
                    builder.append(userId);
                    builder.append(" but is calling from user ");
                    builder.append(UserHandle.getUserId(callingUid));
                    builder.append("; this requires ");
                    builder.append(INTERACT_ACROSS_USERS_FULL);
                    if (allowMode != ALLOW_FULL_ONLY) {
                        builder.append(" or ");
                        builder.append(INTERACT_ACROSS_USERS);
                    }
                    String msg = builder.toString();
                    Slog.w(TAG, msg);
                    throw new SecurityException(msg);
                }
            }
        }
        if (!allowAll && targetUserId < 0) {
            throw new IllegalArgumentException(
                    "Call does not support special user #" + targetUserId);
        }
        // Check shell permission
        if (callingUid == Process.SHELL_UID && targetUserId >= UserHandle.USER_SYSTEM) {
            if (hasUserRestriction(UserManager.DISALLOW_DEBUGGING_FEATURES, targetUserId)) {
                throw new SecurityException("Shell does not have permission to access user "
                        + targetUserId + "\n " + Debug.getCallers(3));
            }
        }
        return targetUserId;
    }

    int unsafeConvertIncomingUserLocked(int userId) {
        return (userId == UserHandle.USER_CURRENT || userId == UserHandle.USER_CURRENT_OR_SELF)
                ? getCurrentUserIdLocked(): userId;
    }

    void registerUserSwitchObserver(IUserSwitchObserver observer, String name) {
        Preconditions.checkNotNull(name, "Observer name cannot be null");
        if (mService.checkCallingPermission(INTERACT_ACROSS_USERS_FULL)
                != PackageManager.PERMISSION_GRANTED) {
            final String msg = "Permission Denial: registerUserSwitchObserver() from pid="
                    + Binder.getCallingPid()
                    + ", uid=" + Binder.getCallingUid()
                    + " requires " + INTERACT_ACROSS_USERS_FULL;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }
        mUserSwitchObservers.register(observer, name);
    }

    void unregisterUserSwitchObserver(IUserSwitchObserver observer) {
        mUserSwitchObservers.unregister(observer);
    }

    UserState getStartedUserStateLocked(int userId) {
        return mStartedUsers.get(userId);
    }

    boolean hasStartedUserState(int userId) {
        return mStartedUsers.get(userId) != null;
    }

    private void updateStartedUserArrayLocked() {
        int num = 0;
        for (int i = 0; i < mStartedUsers.size(); i++) {
            UserState uss = mStartedUsers.valueAt(i);
            // This list does not include stopping users.
            if (uss.state != UserState.STATE_STOPPING
                    && uss.state != UserState.STATE_SHUTDOWN) {
                num++;
            }
        }
        mStartedUserArray = new int[num];
        num = 0;
        for (int i = 0; i < mStartedUsers.size(); i++) {
            UserState uss = mStartedUsers.valueAt(i);
            if (uss.state != UserState.STATE_STOPPING
                    && uss.state != UserState.STATE_SHUTDOWN) {
                mStartedUserArray[num++] = mStartedUsers.keyAt(i);
            }
        }
    }

    void sendBootCompletedLocked(IIntentReceiver resultTo) {
        for (int i = 0; i < mStartedUsers.size(); i++) {
            UserState uss = mStartedUsers.valueAt(i);
            finishUserBoot(uss, resultTo);
        }
    }

    void onSystemReady() {
        updateCurrentProfileIdsLocked();
    }

    /**
     * Refreshes the list of users related to the current user when either a
     * user switch happens or when a new related user is started in the
     * background.
     */
    private void updateCurrentProfileIdsLocked() {
        final List<UserInfo> profiles = getUserManager().getProfiles(mCurrentUserId,
                false /* enabledOnly */);
        int[] currentProfileIds = new int[profiles.size()]; // profiles will not be null
        for (int i = 0; i < currentProfileIds.length; i++) {
            currentProfileIds[i] = profiles.get(i).id;
        }
        mCurrentProfileIds = currentProfileIds;

        synchronized (mUserProfileGroupIdsSelfLocked) {
            mUserProfileGroupIdsSelfLocked.clear();
            final List<UserInfo> users = getUserManager().getUsers(false);
            for (int i = 0; i < users.size(); i++) {
                UserInfo user = users.get(i);
                if (user.profileGroupId != UserInfo.NO_PROFILE_GROUP_ID) {
                    mUserProfileGroupIdsSelfLocked.put(user.id, user.profileGroupId);
                }
            }
        }
    }

    int[] getStartedUserArrayLocked() {
        return mStartedUserArray;
    }

    boolean isUserStoppingOrShuttingDownLocked(int userId) {
        UserState state = getStartedUserStateLocked(userId);
        if (state == null) {
            return false;
        }
        return state.state == UserState.STATE_STOPPING
                || state.state == UserState.STATE_SHUTDOWN;
    }

    boolean isUserRunningLocked(int userId, int flags) {
        UserState state = getStartedUserStateLocked(userId);
        if (state == null) {
            return false;
        }
        if ((flags & ActivityManager.FLAG_OR_STOPPED) != 0) {
            return true;
        }
        if ((flags & ActivityManager.FLAG_AND_LOCKED) != 0) {
            switch (state.state) {
                case UserState.STATE_BOOTING:
                case UserState.STATE_RUNNING_LOCKED:
                    return true;
                default:
                    return false;
            }
        }
        if ((flags & ActivityManager.FLAG_AND_UNLOCKING_OR_UNLOCKED) != 0) {
            switch (state.state) {
                case UserState.STATE_RUNNING_UNLOCKING:
                case UserState.STATE_RUNNING_UNLOCKED:
                    return true;
                default:
                    return false;
            }
        }
        if ((flags & ActivityManager.FLAG_AND_UNLOCKED) != 0) {
            switch (state.state) {
                case UserState.STATE_RUNNING_UNLOCKED:
                    return true;
                default:
                    return false;
            }
        }

        // One way or another, we're running!
        return true;
    }

    UserInfo getCurrentUser() {
        if ((mService.checkCallingPermission(INTERACT_ACROSS_USERS)
                != PackageManager.PERMISSION_GRANTED) && (
                mService.checkCallingPermission(INTERACT_ACROSS_USERS_FULL)
                        != PackageManager.PERMISSION_GRANTED)) {
            String msg = "Permission Denial: getCurrentUser() from pid="
                    + Binder.getCallingPid()
                    + ", uid=" + Binder.getCallingUid()
                    + " requires " + INTERACT_ACROSS_USERS;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }
        synchronized (mService) {
            return getCurrentUserLocked();
        }
    }

    UserInfo getCurrentUserLocked() {
        int userId = mTargetUserId != UserHandle.USER_NULL ? mTargetUserId : mCurrentUserId;
        return getUserInfo(userId);
    }

    int getCurrentOrTargetUserIdLocked() {
        return mTargetUserId != UserHandle.USER_NULL ? mTargetUserId : mCurrentUserId;
    }

    int getCurrentUserIdLocked() {
        return mCurrentUserId;
    }

    private boolean isCurrentUserLocked(int userId) {
        return userId == getCurrentOrTargetUserIdLocked();
    }

    int setTargetUserIdLocked(int targetUserId) {
        return mTargetUserId = targetUserId;
    }

    int[] getUsers() {
        UserManagerService ums = getUserManager();
        return ums != null ? ums.getUserIds() : new int[] { 0 };
    }

    UserInfo getUserInfo(int userId) {
        return getUserManager().getUserInfo(userId);
    }

    int[] getUserIds() {
        return getUserManager().getUserIds();
    }

    boolean exists(int userId) {
        return getUserManager().exists(userId);
    }

    boolean hasUserRestriction(String restriction, int userId) {
        return getUserManager().hasUserRestriction(restriction, userId);
    }

    Set<Integer> getProfileIds(int userId) {
        Set<Integer> userIds = new HashSet<>();
        final List<UserInfo> profiles = getUserManager().getProfiles(userId,
                false /* enabledOnly */);
        for (UserInfo user : profiles) {
            userIds.add(user.id);
        }
        return userIds;
    }

    boolean isSameProfileGroup(int callingUserId, int targetUserId) {
        synchronized (mUserProfileGroupIdsSelfLocked) {
            int callingProfile = mUserProfileGroupIdsSelfLocked.get(callingUserId,
                    UserInfo.NO_PROFILE_GROUP_ID);
            int targetProfile = mUserProfileGroupIdsSelfLocked.get(targetUserId,
                    UserInfo.NO_PROFILE_GROUP_ID);
            return callingProfile != UserInfo.NO_PROFILE_GROUP_ID
                    && callingProfile == targetProfile;
        }
    }

    boolean isCurrentProfileLocked(int userId) {
        return ArrayUtils.contains(mCurrentProfileIds, userId);
    }

    int[] getCurrentProfileIdsLocked() {
        return mCurrentProfileIds;
    }

    /**
     * Returns whether the given user requires credential entry at this time. This is used to
     * intercept activity launches for work apps when the Work Challenge is present.
     */
    boolean shouldConfirmCredentials(int userId) {
        synchronized (mService) {
            if (mStartedUsers.get(userId) == null) {
                return false;
            }
        }
        if (!mLockPatternUtils.isSeparateProfileChallengeEnabled(userId)) {
            return false;
        }
        final KeyguardManager km = (KeyguardManager) mService.mContext
                .getSystemService(KEYGUARD_SERVICE);
        return km.isDeviceLocked(userId) && km.isDeviceSecure(userId);
    }

    boolean isLockScreenDisabled(@UserIdInt int userId) {
        return mLockPatternUtils.isLockScreenDisabled(userId);
    }

    private UserManagerInternal getUserManagerInternal() {
        if (mUserManagerInternal == null) {
            mUserManagerInternal = LocalServices.getService(UserManagerInternal.class);
        }
        return mUserManagerInternal;
    }

    void dump(PrintWriter pw, boolean dumpAll) {
        pw.println("  mStartedUsers:");
        for (int i = 0; i < mStartedUsers.size(); i++) {
            UserState uss = mStartedUsers.valueAt(i);
            pw.print("    User #"); pw.print(uss.mHandle.getIdentifier());
            pw.print(": "); uss.dump("", pw);
        }
        pw.print("  mStartedUserArray: [");
        for (int i = 0; i < mStartedUserArray.length; i++) {
            if (i > 0) pw.print(", ");
            pw.print(mStartedUserArray[i]);
        }
        pw.println("]");
        pw.print("  mUserLru: [");
        for (int i = 0; i < mUserLru.size(); i++) {
            if (i > 0) pw.print(", ");
            pw.print(mUserLru.get(i));
        }
        pw.println("]");
        if (dumpAll) {
            pw.print("  mStartedUserArray: "); pw.println(Arrays.toString(mStartedUserArray));
        }
        synchronized (mUserProfileGroupIdsSelfLocked) {
            if (mUserProfileGroupIdsSelfLocked.size() > 0) {
                pw.println("  mUserProfileGroupIds:");
                for (int i=0; i<mUserProfileGroupIdsSelfLocked.size(); i++) {
                    pw.print("    User #");
                    pw.print(mUserProfileGroupIdsSelfLocked.keyAt(i));
                    pw.print(" -> profile #");
                    pw.println(mUserProfileGroupIdsSelfLocked.valueAt(i));
                }
            }
        }
    }
}