services/core/java/com/android/server/pm/PackageInstallerService.java

/*
 * Copyright (C) 2014 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.pm;

import static org.xmlpull.v1.XmlPullParser.END_DOCUMENT;
import static org.xmlpull.v1.XmlPullParser.START_TAG;

import android.Manifest;
import android.app.ActivityManager;
import android.app.AppGlobals;
import android.app.AppOpsManager;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PackageDeleteObserver;
import android.app.PackageInstallObserver;
import android.app.admin.DevicePolicyEventLogger;
import android.app.admin.DevicePolicyManagerInternal;
import android.content.Context;
import android.content.Intent;
import android.content.IntentSender;
import android.content.IntentSender.SendIntentException;
import android.content.pm.ApplicationInfo;
import android.content.pm.IPackageInstaller;
import android.content.pm.IPackageInstallerCallback;
import android.content.pm.IPackageInstallerSession;
import android.content.pm.PackageInfo;
import android.content.pm.PackageInstaller;
import android.content.pm.PackageInstaller.SessionInfo;
import android.content.pm.PackageInstaller.SessionParams;
import android.content.pm.PackageManager;
import android.content.pm.ParceledListSlice;
import android.content.pm.VersionedPackage;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Binder;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.os.Process;
import android.os.RemoteCallbackList;
import android.os.RemoteException;
import android.os.SELinux;
import android.os.UserManager;
import android.os.storage.StorageManager;
import android.stats.devicepolicy.DevicePolicyEnums;
import android.system.ErrnoException;
import android.system.Os;
import android.text.TextUtils;
import android.text.format.DateUtils;
import android.util.ArraySet;
import android.util.AtomicFile;
import android.util.ExceptionUtils;
import android.util.Slog;
import android.util.SparseArray;
import android.util.SparseBooleanArray;
import android.util.SparseIntArray;
import android.util.Xml;

import com.android.internal.R;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.content.PackageHelper;
import com.android.internal.messages.nano.SystemMessageProto.SystemMessage;
import com.android.internal.notification.SystemNotificationChannels;
import com.android.internal.util.FastXmlSerializer;
import com.android.internal.util.ImageUtils;
import com.android.internal.util.IndentingPrintWriter;
import com.android.server.IoThread;
import com.android.server.LocalServices;
import com.android.server.pm.permission.PermissionManagerServiceInternal;

import libcore.io.IoUtils;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;

import java.io.CharArrayWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.Random;
import java.util.function.IntPredicate;

/** The service responsible for installing packages. */
public class PackageInstallerService extends IPackageInstaller.Stub implements
        PackageSessionProvider {
    private static final String TAG = "PackageInstaller";
    private static final boolean LOGD = false;

    // TODO: remove outstanding sessions when installer package goes away
    // TODO: notify listeners in other users when package has been installed there
    // TODO: purge expired sessions periodically in addition to at reboot

    /** XML constants used in {@link #mSessionsFile} */
    private static final String TAG_SESSIONS = "sessions";

    /** Automatically destroy sessions older than this */
    private static final long MAX_AGE_MILLIS = 3 * DateUtils.DAY_IN_MILLIS;
    /** Automatically destroy staged sessions that have not changed state in this time */
    private static final long MAX_TIME_SINCE_UPDATE_MILLIS = 7 * DateUtils.DAY_IN_MILLIS;
    /** Upper bound on number of active sessions for a UID */
    private static final long MAX_ACTIVE_SESSIONS = 1024;
    /** Upper bound on number of historical sessions for a UID */
    private static final long MAX_HISTORICAL_SESSIONS = 1048576;

    private final Context mContext;
    private final PackageManagerService mPm;
    private final ApexManager mApexManager;
    private final StagingManager mStagingManager;
    private final PermissionManagerServiceInternal mPermissionManager;

    private AppOpsManager mAppOps;

    private final HandlerThread mInstallThread;
    private final Handler mInstallHandler;

    private final Callbacks mCallbacks;

    private volatile boolean mOkToSendBroadcasts = false;

    /**
     * File storing persisted {@link #mSessions} metadata.
     */
    private final AtomicFile mSessionsFile;

    /**
     * Directory storing persisted {@link #mSessions} metadata which is too
     * heavy to store directly in {@link #mSessionsFile}.
     */
    private final File mSessionsDir;

    private final InternalCallback mInternalCallback = new InternalCallback();

    /**
     * Used for generating session IDs. Since this is created at boot time,
     * normal random might be predictable.
     */
    private final Random mRandom = new SecureRandom();

    /** All sessions allocated */
    @GuardedBy("mSessions")
    private final SparseBooleanArray mAllocatedSessions = new SparseBooleanArray();

    @GuardedBy("mSessions")
    private final SparseArray<PackageInstallerSession> mSessions = new SparseArray<>();

    /** Historical sessions kept around for debugging purposes */
    @GuardedBy("mSessions")
    private final List<String> mHistoricalSessions = new ArrayList<>();

    @GuardedBy("mSessions")
    private final SparseIntArray mHistoricalSessionsByInstaller = new SparseIntArray();

    /** Sessions allocated to legacy users */
    @GuardedBy("mSessions")
    private final SparseBooleanArray mLegacySessions = new SparseBooleanArray();

    private static final FilenameFilter sStageFilter = new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
            return isStageName(name);
        }
    };

    public PackageInstallerService(Context context, PackageManagerService pm, ApexManager am) {
        mContext = context;
        mPm = pm;
        mPermissionManager = LocalServices.getService(PermissionManagerServiceInternal.class);

        mInstallThread = new HandlerThread(TAG);
        mInstallThread.start();

        mInstallHandler = new Handler(mInstallThread.getLooper());

        mCallbacks = new Callbacks(mInstallThread.getLooper());

        mSessionsFile = new AtomicFile(
                new File(Environment.getDataSystemDirectory(), "install_sessions.xml"),
                "package-session");
        mSessionsDir = new File(Environment.getDataSystemDirectory(), "install_sessions");
        mSessionsDir.mkdirs();

        mApexManager = am;

        mStagingManager = new StagingManager(this, am, context);
    }

    boolean okToSendBroadcasts()  {
        return mOkToSendBroadcasts;
    }

    public void systemReady() {
        mAppOps = mContext.getSystemService(AppOpsManager.class);

        synchronized (mSessions) {
            readSessionsLocked();

            reconcileStagesLocked(StorageManager.UUID_PRIVATE_INTERNAL);

            final ArraySet<File> unclaimedIcons = newArraySet(
                    mSessionsDir.listFiles());

            // Ignore stages and icons claimed by active sessions
            for (int i = 0; i < mSessions.size(); i++) {
                final PackageInstallerSession session = mSessions.valueAt(i);
                unclaimedIcons.remove(buildAppIconFile(session.sessionId));
            }

            // Clean up orphaned icons
            for (File icon : unclaimedIcons) {
                Slog.w(TAG, "Deleting orphan icon " + icon);
                icon.delete();
            }

            // Invalid sessions might have been marked while parsing. Re-write the database with
            // the updated information.
            writeSessionsLocked();

        }
    }

    void restoreAndApplyStagedSessionIfNeeded() {
        List<PackageInstallerSession> stagedSessionsToRestore = new ArrayList<>();
        synchronized (mSessions) {
            for (int i = 0; i < mSessions.size(); i++) {
                final PackageInstallerSession session = mSessions.valueAt(i);
                if (session.isStaged()) {
                    stagedSessionsToRestore.add(session);
                }
            }
        }
        // Don't hold mSessions lock when calling restoreSession, since it might trigger an APK
        // atomic install which needs to query sessions, which requires lock on mSessions.
        for (PackageInstallerSession session : stagedSessionsToRestore) {
            mStagingManager.restoreSession(session);
        }
        // Broadcasts are not sent while we restore sessions on boot, since no processes would be
        // ready to listen to them. From now on, we greedily assume that broadcasts requests are
        // safe to send out. The worst that can happen is that a broadcast is attempted before
        // ActivityManagerService completes its own systemReady(), in which case it will be rejected
        // with an otherwise harmless exception.
        // A more appropriate way to do this would be to wait until the correct  boot phase is
        // reached, but since we are not a SystemService we can't override onBootPhase.
        // Waiting on the BOOT_COMPLETED broadcast can take several minutes, so that's not a viable
        // way either.
        mOkToSendBroadcasts = true;
    }

    @GuardedBy("mSessions")
    private void reconcileStagesLocked(String volumeUuid) {
        final File stagingDir = getTmpSessionDir(volumeUuid);
        final ArraySet<File> unclaimedStages = newArraySet(
                stagingDir.listFiles(sStageFilter));

        // Ignore stages claimed by active sessions
        for (int i = 0; i < mSessions.size(); i++) {
            final PackageInstallerSession session = mSessions.valueAt(i);
            unclaimedStages.remove(session.stageDir);
        }

        // Clean up orphaned staging directories
        for (File stage : unclaimedStages) {
            Slog.w(TAG, "Deleting orphan stage " + stage);
            synchronized (mPm.mInstallLock) {
                mPm.removeCodePathLI(stage);
            }
        }
    }

    public void onPrivateVolumeMounted(String volumeUuid) {
        synchronized (mSessions) {
            reconcileStagesLocked(volumeUuid);
        }
    }

    public static boolean isStageName(String name) {
        final boolean isFile = name.startsWith("vmdl") && name.endsWith(".tmp");
        final boolean isContainer = name.startsWith("smdl") && name.endsWith(".tmp");
        final boolean isLegacyContainer = name.startsWith("smdl2tmp");
        return isFile || isContainer || isLegacyContainer;
    }

    @Deprecated
    public File allocateStageDirLegacy(String volumeUuid, boolean isEphemeral) throws IOException {
        synchronized (mSessions) {
            try {
                final int sessionId = allocateSessionIdLocked();
                mLegacySessions.put(sessionId, true);
                final File sessionStageDir = buildTmpSessionDir(sessionId, volumeUuid);
                prepareStageDir(sessionStageDir);
                return sessionStageDir;
            } catch (IllegalStateException e) {
                throw new IOException(e);
            }
        }
    }

    @Deprecated
    public String allocateExternalStageCidLegacy() {
        synchronized (mSessions) {
            final int sessionId = allocateSessionIdLocked();
            mLegacySessions.put(sessionId, true);
            return "smdl" + sessionId + ".tmp";
        }
    }

    @GuardedBy("mSessions")
    private void readSessionsLocked() {
        if (LOGD) Slog.v(TAG, "readSessionsLocked()");

        mSessions.clear();

        FileInputStream fis = null;
        try {
            fis = mSessionsFile.openRead();
            final XmlPullParser in = Xml.newPullParser();
            in.setInput(fis, StandardCharsets.UTF_8.name());

            int type;
            while ((type = in.next()) != END_DOCUMENT) {
                if (type == START_TAG) {
                    final String tag = in.getName();
                    if (PackageInstallerSession.TAG_SESSION.equals(tag)) {
                        final PackageInstallerSession session;
                        try {
                            session = PackageInstallerSession.readFromXml(in, mInternalCallback,
                                    mContext, mPm, mInstallThread.getLooper(), mStagingManager,
                                    mSessionsDir, this);
                        } catch (Exception e) {
                            Slog.e(TAG, "Could not read session", e);
                            continue;
                        }

                        final long age = System.currentTimeMillis() - session.createdMillis;
                        final long timeSinceUpdate =
                                System.currentTimeMillis() - session.getUpdatedMillis();
                        final boolean valid;
                        if (session.isStaged()) {
                            if (timeSinceUpdate >= MAX_TIME_SINCE_UPDATE_MILLIS
                                    && session.isStagedAndInTerminalState()) {
                                valid = false;
                            } else {
                                valid = true;
                            }
                        } else if (age >= MAX_AGE_MILLIS) {
                            Slog.w(TAG, "Abandoning old session created at "
                                        + session.createdMillis);
                            valid = false;
                        } else {
                            valid = true;
                        }

                        if (valid) {
                            mSessions.put(session.sessionId, session);
                        } else {
                            // Since this is early during boot we don't send
                            // any observer events about the session, but we
                            // keep details around for dumpsys.
                            addHistoricalSessionLocked(session);
                        }
                        mAllocatedSessions.put(session.sessionId, true);
                    }
                }
            }
        } catch (FileNotFoundException e) {
            // Missing sessions are okay, probably first boot
        } catch (IOException | XmlPullParserException e) {
            Slog.wtf(TAG, "Failed reading install sessions", e);
        } finally {
            IoUtils.closeQuietly(fis);
        }
        // After all of the sessions were loaded, they are ready to be sealed and validated
        for (int i = 0; i < mSessions.size(); ++i) {
            PackageInstallerSession session = mSessions.valueAt(i);
            session.sealAndValidateIfNecessary();
        }
    }

    @GuardedBy("mSessions")
    private void addHistoricalSessionLocked(PackageInstallerSession session) {
        CharArrayWriter writer = new CharArrayWriter();
        IndentingPrintWriter pw = new IndentingPrintWriter(writer, "    ");
        session.dump(pw);
        mHistoricalSessions.add(writer.toString());

        int installerUid = session.getInstallerUid();
        // Increment the number of sessions by this installerUid.
        mHistoricalSessionsByInstaller.put(installerUid,
                mHistoricalSessionsByInstaller.get(installerUid) + 1);
    }

    @GuardedBy("mSessions")
    private void writeSessionsLocked() {
        if (LOGD) Slog.v(TAG, "writeSessionsLocked()");

        FileOutputStream fos = null;
        try {
            fos = mSessionsFile.startWrite();

            XmlSerializer out = new FastXmlSerializer();
            out.setOutput(fos, StandardCharsets.UTF_8.name());
            out.startDocument(null, true);
            out.startTag(null, TAG_SESSIONS);
            final int size = mSessions.size();
            for (int i = 0; i < size; i++) {
                final PackageInstallerSession session = mSessions.valueAt(i);
                session.write(out, mSessionsDir);
            }
            out.endTag(null, TAG_SESSIONS);
            out.endDocument();

            mSessionsFile.finishWrite(fos);
        } catch (IOException e) {
            if (fos != null) {
                mSessionsFile.failWrite(fos);
            }
        }
    }

    private File buildAppIconFile(int sessionId) {
        return new File(mSessionsDir, "app_icon." + sessionId + ".png");
    }

    private void writeSessionsAsync() {
        IoThread.getHandler().post(new Runnable() {
            @Override
            public void run() {
                synchronized (mSessions) {
                    writeSessionsLocked();
                }
            }
        });
    }

    @Override
    public int createSession(SessionParams params, String installerPackageName, int userId) {
        try {
            return createSessionInternal(params, installerPackageName, userId);
        } catch (IOException e) {
            throw ExceptionUtils.wrap(e);
        }
    }

    private int createSessionInternal(SessionParams params, String installerPackageName, int userId)
            throws IOException {
        final int callingUid = Binder.getCallingUid();
        mPermissionManager.enforceCrossUserPermission(
                callingUid, userId, true, true, "createSession");

        if (mPm.isUserRestricted(userId, UserManager.DISALLOW_INSTALL_APPS)) {
            throw new SecurityException("User restriction prevents installing");
        }

        if ((callingUid == Process.SHELL_UID) || (callingUid == Process.ROOT_UID)) {
            params.installFlags |= PackageManager.INSTALL_FROM_ADB;

        } else {
            // Only apps with INSTALL_PACKAGES are allowed to set an installer that is not the
            // caller.
            if (mContext.checkCallingOrSelfPermission(Manifest.permission.INSTALL_PACKAGES) !=
                    PackageManager.PERMISSION_GRANTED) {
                mAppOps.checkPackage(callingUid, installerPackageName);
            }

            params.installFlags &= ~PackageManager.INSTALL_FROM_ADB;
            params.installFlags &= ~PackageManager.INSTALL_ALL_USERS;
            params.installFlags &= ~PackageManager.INSTALL_ALLOW_TEST;
            params.installFlags |= PackageManager.INSTALL_REPLACE_EXISTING;
            if ((params.installFlags & PackageManager.INSTALL_VIRTUAL_PRELOAD) != 0
                    && !mPm.isCallerVerifier(callingUid)) {
                params.installFlags &= ~PackageManager.INSTALL_VIRTUAL_PRELOAD;
            }
        }

        if (Build.IS_DEBUGGABLE || isDowngradeAllowedForCaller(callingUid)) {
            params.installFlags |= PackageManager.INSTALL_ALLOW_DOWNGRADE;
        } else {
            params.installFlags &= ~PackageManager.INSTALL_ALLOW_DOWNGRADE;
            params.installFlags &= ~PackageManager.INSTALL_REQUEST_DOWNGRADE;
        }

        if (callingUid != Process.SYSTEM_UID) {
            // Only system_server can use INSTALL_DISABLE_VERIFICATION.
            params.installFlags &= ~PackageManager.INSTALL_DISABLE_VERIFICATION;
        }

        boolean isApex = (params.installFlags & PackageManager.INSTALL_APEX) != 0;
        if (params.isStaged || isApex) {
            mContext.enforceCallingOrSelfPermission(Manifest.permission.INSTALL_PACKAGES, TAG);
        }

        if (isApex) {
            if (!mApexManager.isApexSupported()) {
                throw new IllegalArgumentException(
                    "This device doesn't support the installation of APEX files");
            }
            if (!params.isStaged) {
                throw new IllegalArgumentException(
                    "APEX files can only be installed as part of a staged session.");
            }
        }

        if (!params.isMultiPackage) {
            // Only system components can circumvent runtime permissions when installing.
            if ((params.installFlags & PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS) != 0
                    && mContext.checkCallingOrSelfPermission(Manifest.permission
                    .INSTALL_GRANT_RUNTIME_PERMISSIONS) == PackageManager.PERMISSION_DENIED) {
                throw new SecurityException("You need the "
                        + "android.permission.INSTALL_GRANT_RUNTIME_PERMISSIONS permission "
                        + "to use the PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS flag");
            }

            // Defensively resize giant app icons
            if (params.appIcon != null) {
                final ActivityManager am = (ActivityManager) mContext.getSystemService(
                        Context.ACTIVITY_SERVICE);
                final int iconSize = am.getLauncherLargeIconSize();
                if ((params.appIcon.getWidth() > iconSize * 2)
                        || (params.appIcon.getHeight() > iconSize * 2)) {
                    params.appIcon = Bitmap.createScaledBitmap(params.appIcon, iconSize, iconSize,
                            true);
                }
            }

            switch (params.mode) {
                case SessionParams.MODE_FULL_INSTALL:
                case SessionParams.MODE_INHERIT_EXISTING:
                    break;
                default:
                    throw new IllegalArgumentException("Invalid install mode: " + params.mode);
            }

            // If caller requested explicit location, sanity check it, otherwise
            // resolve the best internal or adopted location.
            if ((params.installFlags & PackageManager.INSTALL_INTERNAL) != 0) {
                if (!PackageHelper.fitsOnInternal(mContext, params)) {
                    throw new IOException("No suitable internal storage available");
                }
            } else if ((params.installFlags & PackageManager.INSTALL_FORCE_VOLUME_UUID) != 0) {
                // For now, installs to adopted media are treated as internal from
                // an install flag point-of-view.
                params.installFlags |= PackageManager.INSTALL_INTERNAL;
            } else {
                params.installFlags |= PackageManager.INSTALL_INTERNAL;

                // Resolve best location for install, based on combination of
                // requested install flags, delta size, and manifest settings.
                final long ident = Binder.clearCallingIdentity();
                try {
                    params.volumeUuid = PackageHelper.resolveInstallVolume(mContext, params);
                } finally {
                    Binder.restoreCallingIdentity(ident);
                }
            }
        }

        final int sessionId;
        final PackageInstallerSession session;
        synchronized (mSessions) {
            // Sanity check that installer isn't going crazy
            final int activeCount = getSessionCount(mSessions, callingUid);
            if (activeCount >= MAX_ACTIVE_SESSIONS) {
                throw new IllegalStateException(
                        "Too many active sessions for UID " + callingUid);
            }
            final int historicalCount = mHistoricalSessionsByInstaller.get(callingUid);
            if (historicalCount >= MAX_HISTORICAL_SESSIONS) {
                throw new IllegalStateException(
                        "Too many historical sessions for UID " + callingUid);
            }

            sessionId = allocateSessionIdLocked();
        }

        final long createdMillis = System.currentTimeMillis();
        // We're staging to exactly one location
        File stageDir = null;
        String stageCid = null;
        if (!params.isMultiPackage) {
            if ((params.installFlags & PackageManager.INSTALL_INTERNAL) != 0) {
                stageDir = buildSessionDir(sessionId, params);
            } else {
                stageCid = buildExternalStageCid(sessionId);
            }
        }
        session = new PackageInstallerSession(mInternalCallback, mContext, mPm, this,
                mInstallThread.getLooper(), mStagingManager, sessionId, userId,
                installerPackageName, callingUid, params, createdMillis, stageDir, stageCid, false,
                false, false, null, SessionInfo.INVALID_ID, false, false, false,
                SessionInfo.STAGED_SESSION_NO_ERROR, "");

        synchronized (mSessions) {
            mSessions.put(sessionId, session);
        }
        if (params.isStaged) {
            mStagingManager.createSession(session);
        }

        if ((session.params.installFlags & PackageManager.INSTALL_DRY_RUN) == 0) {
            mCallbacks.notifySessionCreated(session.sessionId, session.userId);
        }
        writeSessionsAsync();
        return sessionId;
    }

    private boolean isDowngradeAllowedForCaller(int callingUid) {
        return callingUid == Process.SYSTEM_UID || callingUid == Process.ROOT_UID
                || callingUid == Process.SHELL_UID;
    }

    @Override
    public void updateSessionAppIcon(int sessionId, Bitmap appIcon) {
        synchronized (mSessions) {
            final PackageInstallerSession session = mSessions.get(sessionId);
            if (session == null || !isCallingUidOwner(session)) {
                throw new SecurityException("Caller has no access to session " + sessionId);
            }

            // Defensively resize giant app icons
            if (appIcon != null) {
                final ActivityManager am = (ActivityManager) mContext.getSystemService(
                        Context.ACTIVITY_SERVICE);
                final int iconSize = am.getLauncherLargeIconSize();
                if ((appIcon.getWidth() > iconSize * 2)
                        || (appIcon.getHeight() > iconSize * 2)) {
                    appIcon = Bitmap.createScaledBitmap(appIcon, iconSize, iconSize, true);
                }
            }

            session.params.appIcon = appIcon;
            session.params.appIconLastModified = -1;

            mInternalCallback.onSessionBadgingChanged(session);
        }
    }

    @Override
    public void updateSessionAppLabel(int sessionId, String appLabel) {
        synchronized (mSessions) {
            final PackageInstallerSession session = mSessions.get(sessionId);
            if (session == null || !isCallingUidOwner(session)) {
                throw new SecurityException("Caller has no access to session " + sessionId);
            }
            session.params.appLabel = appLabel;
            mInternalCallback.onSessionBadgingChanged(session);
        }
    }

    @Override
    public void abandonSession(int sessionId) {
        synchronized (mSessions) {
            final PackageInstallerSession session = mSessions.get(sessionId);
            if (session == null || !isCallingUidOwner(session)) {
                throw new SecurityException("Caller has no access to session " + sessionId);
            }
            session.abandon();
        }
    }

    @Override
    public IPackageInstallerSession openSession(int sessionId) {
        try {
            return openSessionInternal(sessionId);
        } catch (IOException e) {
            throw ExceptionUtils.wrap(e);
        }
    }

    private IPackageInstallerSession openSessionInternal(int sessionId) throws IOException {
        synchronized (mSessions) {
            final PackageInstallerSession session = mSessions.get(sessionId);
            if (session == null || !isCallingUidOwner(session)) {
                throw new SecurityException("Caller has no access to session " + sessionId);
            }
            session.open();
            return session;
        }
    }

    @GuardedBy("mSessions")
    private int allocateSessionIdLocked() {
        int n = 0;
        int sessionId;
        do {
            sessionId = mRandom.nextInt(Integer.MAX_VALUE - 1) + 1;
            if (!mAllocatedSessions.get(sessionId, false)) {
                mAllocatedSessions.put(sessionId, true);
                return sessionId;
            }
        } while (n++ < 32);

        throw new IllegalStateException("Failed to allocate session ID");
    }

    private File getTmpSessionDir(String volumeUuid) {
        return Environment.getDataAppDirectory(volumeUuid);
    }

    private File buildTmpSessionDir(int sessionId, String volumeUuid) {
        final File sessionStagingDir = getTmpSessionDir(volumeUuid);
        return new File(sessionStagingDir, "vmdl" + sessionId + ".tmp");
    }

    private File buildSessionDir(int sessionId, SessionParams params) {
        if (params.isStaged) {
            final File sessionStagingDir = Environment.getDataStagingDirectory(params.volumeUuid);
            return new File(sessionStagingDir, "session_" + sessionId);
        }
        return buildTmpSessionDir(sessionId, params.volumeUuid);
    }

    static void prepareStageDir(File stageDir) throws IOException {
        if (stageDir.exists()) {
            throw new IOException("Session dir already exists: " + stageDir);
        }

        try {
            Os.mkdir(stageDir.getAbsolutePath(), 0775);
            Os.chmod(stageDir.getAbsolutePath(), 0775);
        } catch (ErrnoException e) {
            // This purposefully throws if directory already exists
            throw new IOException("Failed to prepare session dir: " + stageDir, e);
        }

        if (!SELinux.restorecon(stageDir)) {
            throw new IOException("Failed to restorecon session dir: " + stageDir);
        }
    }

    private String buildExternalStageCid(int sessionId) {
        return "smdl" + sessionId + ".tmp";
    }

    @Override
    public SessionInfo getSessionInfo(int sessionId) {
        synchronized (mSessions) {
            final PackageInstallerSession session = mSessions.get(sessionId);
            return session != null ? session.generateInfo() : null;
        }
    }

    @Override
    public ParceledListSlice<SessionInfo> getStagedSessions() {
        return mStagingManager.getSessions();
    }

    @Override
    public ParceledListSlice<SessionInfo> getAllSessions(int userId) {
        mPermissionManager.enforceCrossUserPermission(
                Binder.getCallingUid(), userId, true, false, "getAllSessions");

        final List<SessionInfo> result = new ArrayList<>();
        synchronized (mSessions) {
            for (int i = 0; i < mSessions.size(); i++) {
                final PackageInstallerSession session = mSessions.valueAt(i);
                if (session.userId == userId && !session.hasParentSessionId()) {
                    result.add(session.generateInfo(false));
                }
            }
        }
        return new ParceledListSlice<>(result);
    }

    @Override
    public ParceledListSlice<SessionInfo> getMySessions(String installerPackageName, int userId) {
        mPermissionManager.enforceCrossUserPermission(
                Binder.getCallingUid(), userId, true, false, "getMySessions");
        mAppOps.checkPackage(Binder.getCallingUid(), installerPackageName);

        final List<SessionInfo> result = new ArrayList<>();
        synchronized (mSessions) {
            for (int i = 0; i < mSessions.size(); i++) {
                final PackageInstallerSession session = mSessions.valueAt(i);

                SessionInfo info = session.generateInfo(false);
                if (Objects.equals(info.getInstallerPackageName(), installerPackageName)
                        && session.userId == userId && !session.hasParentSessionId()) {
                    result.add(info);
                }
            }
        }
        return new ParceledListSlice<>(result);
    }

    @Override
    public void uninstall(VersionedPackage versionedPackage, String callerPackageName, int flags,
                IntentSender statusReceiver, int userId) {
        final int callingUid = Binder.getCallingUid();
        mPermissionManager.enforceCrossUserPermission(callingUid, userId, true, true, "uninstall");
        if ((callingUid != Process.SHELL_UID) && (callingUid != Process.ROOT_UID)) {
            mAppOps.checkPackage(callingUid, callerPackageName);
        }

        // Check whether the caller is device owner or affiliated profile owner, in which case we do
        // it silently.
        DevicePolicyManagerInternal dpmi =
                LocalServices.getService(DevicePolicyManagerInternal.class);
        final boolean canSilentlyInstallPackage =
                dpmi != null && dpmi.canSilentlyInstallPackage(callerPackageName, callingUid);

        final PackageDeleteObserverAdapter adapter = new PackageDeleteObserverAdapter(mContext,
                statusReceiver, versionedPackage.getPackageName(),
                canSilentlyInstallPackage, userId);
        if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DELETE_PACKAGES)
                    == PackageManager.PERMISSION_GRANTED) {
            // Sweet, call straight through!
            mPm.deletePackageVersioned(versionedPackage, adapter.getBinder(), userId, flags);
        } else if (canSilentlyInstallPackage) {
            // Allow the device owner and affiliated profile owner to silently delete packages
            // Need to clear the calling identity to get DELETE_PACKAGES permission
            long ident = Binder.clearCallingIdentity();
            try {
                mPm.deletePackageVersioned(versionedPackage, adapter.getBinder(), userId, flags);
            } finally {
                Binder.restoreCallingIdentity(ident);
            }
            DevicePolicyEventLogger
                    .createEvent(DevicePolicyEnums.UNINSTALL_PACKAGE)
                    .setAdmin(callerPackageName)
                    .write();
        } else {
            ApplicationInfo appInfo = mPm.getApplicationInfo(callerPackageName, 0, userId);
            if (appInfo.targetSdkVersion >= Build.VERSION_CODES.P) {
                mContext.enforceCallingOrSelfPermission(Manifest.permission.REQUEST_DELETE_PACKAGES,
                        null);
            }

            // Take a short detour to confirm with user
            final Intent intent = new Intent(Intent.ACTION_UNINSTALL_PACKAGE);
            intent.setData(Uri.fromParts("package", versionedPackage.getPackageName(), null));
            intent.putExtra(PackageInstaller.EXTRA_CALLBACK, adapter.getBinder().asBinder());
            adapter.onUserActionRequired(intent);
        }
    }

    @Override
    public void installExistingPackage(String packageName, int installFlags, int installReason,
            IntentSender statusReceiver, int userId, List<String> whiteListedPermissions) {
        mPm.installExistingPackageAsUser(packageName, userId, installFlags, installReason,
                whiteListedPermissions, statusReceiver);
    }

    @Override
    public void setPermissionsResult(int sessionId, boolean accepted) {
        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.INSTALL_PACKAGES, TAG);

        synchronized (mSessions) {
            PackageInstallerSession session = mSessions.get(sessionId);
            if (session != null) {
                session.setPermissionsResult(accepted);
            }
        }
    }

    @Override
    public void registerCallback(IPackageInstallerCallback callback, int userId) {
        mPermissionManager.enforceCrossUserPermission(
                Binder.getCallingUid(), userId, true, false, "registerCallback");
        registerCallback(callback, eventUserId -> userId == eventUserId);
    }

    /**
     * Assume permissions already checked and caller's identity cleared
     */
    public void registerCallback(IPackageInstallerCallback callback, IntPredicate userCheck) {
        mCallbacks.register(callback, userCheck);
    }

    @Override
    public void unregisterCallback(IPackageInstallerCallback callback) {
        mCallbacks.unregister(callback);
    }

    @Override
    public PackageInstallerSession getSession(int sessionId) {
        synchronized (mSessions) {
            return mSessions.get(sessionId);
        }
    }

    private static int getSessionCount(SparseArray<PackageInstallerSession> sessions,
            int installerUid) {
        int count = 0;
        final int size = sessions.size();
        for (int i = 0; i < size; i++) {
            final PackageInstallerSession session = sessions.valueAt(i);
            if (session.getInstallerUid() == installerUid) {
                count++;
            }
        }
        return count;
    }

    private boolean isCallingUidOwner(PackageInstallerSession session) {
        final int callingUid = Binder.getCallingUid();
        if (callingUid == Process.ROOT_UID) {
            return true;
        } else {
            return (session != null) && (callingUid == session.getInstallerUid());
        }
    }

    static class PackageDeleteObserverAdapter extends PackageDeleteObserver {
        private final Context mContext;
        private final IntentSender mTarget;
        private final String mPackageName;
        private final Notification mNotification;

        public PackageDeleteObserverAdapter(Context context, IntentSender target,
                String packageName, boolean showNotification, int userId) {
            mContext = context;
            mTarget = target;
            mPackageName = packageName;
            if (showNotification) {
                mNotification = buildSuccessNotification(mContext,
                        mContext.getResources().getString(R.string.package_deleted_device_owner),
                        packageName,
                        userId);
            } else {
                mNotification = null;
            }
        }

        @Override
        public void onUserActionRequired(Intent intent) {
            if (mTarget == null) {
                return;
            }
            final Intent fillIn = new Intent();
            fillIn.putExtra(PackageInstaller.EXTRA_PACKAGE_NAME, mPackageName);
            fillIn.putExtra(PackageInstaller.EXTRA_STATUS,
                    PackageInstaller.STATUS_PENDING_USER_ACTION);
            fillIn.putExtra(Intent.EXTRA_INTENT, intent);
            try {
                mTarget.sendIntent(mContext, 0, fillIn, null, null);
            } catch (SendIntentException ignored) {
            }
        }

        @Override
        public void onPackageDeleted(String basePackageName, int returnCode, String msg) {
            if (PackageManager.DELETE_SUCCEEDED == returnCode && mNotification != null) {
                NotificationManager notificationManager = (NotificationManager)
                        mContext.getSystemService(Context.NOTIFICATION_SERVICE);
                notificationManager.notify(basePackageName,
                        SystemMessage.NOTE_PACKAGE_STATE,
                        mNotification);
            }
            if (mTarget == null) {
                return;
            }
            final Intent fillIn = new Intent();
            fillIn.putExtra(PackageInstaller.EXTRA_PACKAGE_NAME, mPackageName);
            fillIn.putExtra(PackageInstaller.EXTRA_STATUS,
                    PackageManager.deleteStatusToPublicStatus(returnCode));
            fillIn.putExtra(PackageInstaller.EXTRA_STATUS_MESSAGE,
                    PackageManager.deleteStatusToString(returnCode, msg));
            fillIn.putExtra(PackageInstaller.EXTRA_LEGACY_STATUS, returnCode);
            try {
                mTarget.sendIntent(mContext, 0, fillIn, null, null);
            } catch (SendIntentException ignored) {
            }
        }
    }

    static class PackageInstallObserverAdapter extends PackageInstallObserver {
        private final Context mContext;
        private final IntentSender mTarget;
        private final int mSessionId;
        private final boolean mShowNotification;
        private final int mUserId;

        public PackageInstallObserverAdapter(Context context, IntentSender target, int sessionId,
                boolean showNotification, int userId) {
            mContext = context;
            mTarget = target;
            mSessionId = sessionId;
            mShowNotification = showNotification;
            mUserId = userId;
        }

        @Override
        public void onUserActionRequired(Intent intent) {
            final Intent fillIn = new Intent();
            fillIn.putExtra(PackageInstaller.EXTRA_SESSION_ID, mSessionId);
            fillIn.putExtra(PackageInstaller.EXTRA_STATUS,
                    PackageInstaller.STATUS_PENDING_USER_ACTION);
            fillIn.putExtra(Intent.EXTRA_INTENT, intent);
            try {
                mTarget.sendIntent(mContext, 0, fillIn, null, null);
            } catch (SendIntentException ignored) {
            }
        }

        @Override
        public void onPackageInstalled(String basePackageName, int returnCode, String msg,
                Bundle extras) {
            if (PackageManager.INSTALL_SUCCEEDED == returnCode && mShowNotification) {
                boolean update = (extras != null) && extras.getBoolean(Intent.EXTRA_REPLACING);
                Notification notification = buildSuccessNotification(mContext,
                        mContext.getResources()
                                .getString(update ? R.string.package_updated_device_owner :
                                        R.string.package_installed_device_owner),
                        basePackageName,
                        mUserId);
                if (notification != null) {
                    NotificationManager notificationManager = (NotificationManager)
                            mContext.getSystemService(Context.NOTIFICATION_SERVICE);
                    notificationManager.notify(basePackageName,
                            SystemMessage.NOTE_PACKAGE_STATE,
                            notification);
                }
            }
            final Intent fillIn = new Intent();
            fillIn.putExtra(PackageInstaller.EXTRA_PACKAGE_NAME, basePackageName);
            fillIn.putExtra(PackageInstaller.EXTRA_SESSION_ID, mSessionId);
            fillIn.putExtra(PackageInstaller.EXTRA_STATUS,
                    PackageManager.installStatusToPublicStatus(returnCode));
            fillIn.putExtra(PackageInstaller.EXTRA_STATUS_MESSAGE,
                    PackageManager.installStatusToString(returnCode, msg));
            fillIn.putExtra(PackageInstaller.EXTRA_LEGACY_STATUS, returnCode);
            if (extras != null) {
                final String existing = extras.getString(
                        PackageManager.EXTRA_FAILURE_EXISTING_PACKAGE);
                if (!TextUtils.isEmpty(existing)) {
                    fillIn.putExtra(PackageInstaller.EXTRA_OTHER_PACKAGE_NAME, existing);
                }
            }
            try {
                mTarget.sendIntent(mContext, 0, fillIn, null, null);
            } catch (SendIntentException ignored) {
            }
        }
    }

    /**
     * Build a notification for package installation / deletion by device owners that is shown if
     * the operation succeeds.
     */
    private static Notification buildSuccessNotification(Context context, String contentText,
            String basePackageName, int userId) {
        PackageInfo packageInfo = null;
        try {
            packageInfo = AppGlobals.getPackageManager().getPackageInfo(
                    basePackageName, PackageManager.MATCH_STATIC_SHARED_LIBRARIES, userId);
        } catch (RemoteException ignored) {
        }
        if (packageInfo == null || packageInfo.applicationInfo == null) {
            Slog.w(TAG, "Notification not built for package: " + basePackageName);
            return null;
        }
        PackageManager pm = context.getPackageManager();
        Bitmap packageIcon = ImageUtils.buildScaledBitmap(
                packageInfo.applicationInfo.loadIcon(pm),
                context.getResources().getDimensionPixelSize(
                        android.R.dimen.notification_large_icon_width),
                context.getResources().getDimensionPixelSize(
                        android.R.dimen.notification_large_icon_height));
        CharSequence packageLabel = packageInfo.applicationInfo.loadLabel(pm);
        return new Notification.Builder(context, SystemNotificationChannels.DEVICE_ADMIN)
                .setSmallIcon(R.drawable.ic_check_circle_24px)
                .setColor(context.getResources().getColor(
                        R.color.system_notification_accent_color))
                .setContentTitle(packageLabel)
                .setContentText(contentText)
                .setStyle(new Notification.BigTextStyle().bigText(contentText))
                .setLargeIcon(packageIcon)
                .build();
    }

    public static <E> ArraySet<E> newArraySet(E... elements) {
        final ArraySet<E> set = new ArraySet<E>();
        if (elements != null) {
            set.ensureCapacity(elements.length);
            Collections.addAll(set, elements);
        }
        return set;
    }

    private static class Callbacks extends Handler {
        private static final int MSG_SESSION_CREATED = 1;
        private static final int MSG_SESSION_BADGING_CHANGED = 2;
        private static final int MSG_SESSION_ACTIVE_CHANGED = 3;
        private static final int MSG_SESSION_PROGRESS_CHANGED = 4;
        private static final int MSG_SESSION_FINISHED = 5;

        private final RemoteCallbackList<IPackageInstallerCallback>
                mCallbacks = new RemoteCallbackList<>();

        public Callbacks(Looper looper) {
            super(looper);
        }

        public void register(IPackageInstallerCallback callback, IntPredicate userCheck) {
            mCallbacks.register(callback, userCheck);
        }

        public void unregister(IPackageInstallerCallback callback) {
            mCallbacks.unregister(callback);
        }

        @Override
        public void handleMessage(Message msg) {
            final int userId = msg.arg2;
            final int n = mCallbacks.beginBroadcast();
            for (int i = 0; i < n; i++) {
                final IPackageInstallerCallback callback = mCallbacks.getBroadcastItem(i);
                final IntPredicate userCheck = (IntPredicate) mCallbacks.getBroadcastCookie(i);
                if (userCheck.test(userId)) {
                    try {
                        invokeCallback(callback, msg);
                    } catch (RemoteException ignored) {
                    }
                }
            }
            mCallbacks.finishBroadcast();
        }

        private void invokeCallback(IPackageInstallerCallback callback, Message msg)
                throws RemoteException {
            final int sessionId = msg.arg1;
            switch (msg.what) {
                case MSG_SESSION_CREATED:
                    callback.onSessionCreated(sessionId);
                    break;
                case MSG_SESSION_BADGING_CHANGED:
                    callback.onSessionBadgingChanged(sessionId);
                    break;
                case MSG_SESSION_ACTIVE_CHANGED:
                    callback.onSessionActiveChanged(sessionId, (boolean) msg.obj);
                    break;
                case MSG_SESSION_PROGRESS_CHANGED:
                    callback.onSessionProgressChanged(sessionId, (float) msg.obj);
                    break;
                case MSG_SESSION_FINISHED:
                    callback.onSessionFinished(sessionId, (boolean) msg.obj);
                    break;
            }
        }

        private void notifySessionCreated(int sessionId, int userId) {
            obtainMessage(MSG_SESSION_CREATED, sessionId, userId).sendToTarget();
        }

        private void notifySessionBadgingChanged(int sessionId, int userId) {
            obtainMessage(MSG_SESSION_BADGING_CHANGED, sessionId, userId).sendToTarget();
        }

        private void notifySessionActiveChanged(int sessionId, int userId, boolean active) {
            obtainMessage(MSG_SESSION_ACTIVE_CHANGED, sessionId, userId, active).sendToTarget();
        }

        private void notifySessionProgressChanged(int sessionId, int userId, float progress) {
            obtainMessage(MSG_SESSION_PROGRESS_CHANGED, sessionId, userId, progress).sendToTarget();
        }

        public void notifySessionFinished(int sessionId, int userId, boolean success) {
            obtainMessage(MSG_SESSION_FINISHED, sessionId, userId, success).sendToTarget();
        }
    }

    void dump(IndentingPrintWriter pw) {
        synchronized (mSessions) {
            pw.println("Active install sessions:");
            pw.increaseIndent();
            int N = mSessions.size();
            for (int i = 0; i < N; i++) {
                final PackageInstallerSession session = mSessions.valueAt(i);
                session.dump(pw);
                pw.println();
            }
            pw.println();
            pw.decreaseIndent();

            pw.println("Historical install sessions:");
            pw.increaseIndent();
            N = mHistoricalSessions.size();
            for (int i = 0; i < N; i++) {
                pw.print(mHistoricalSessions.get(i));
                pw.println();
            }
            pw.println();
            pw.decreaseIndent();

            pw.println("Legacy install sessions:");
            pw.increaseIndent();
            pw.println(mLegacySessions.toString());
            pw.decreaseIndent();
        }
    }

    class InternalCallback {
        public void onSessionBadgingChanged(PackageInstallerSession session) {
            if ((session.params.installFlags & PackageManager.INSTALL_DRY_RUN) == 0) {
                mCallbacks.notifySessionBadgingChanged(session.sessionId, session.userId);
            }

            writeSessionsAsync();
        }

        public void onSessionActiveChanged(PackageInstallerSession session, boolean active) {
            if ((session.params.installFlags & PackageManager.INSTALL_DRY_RUN) == 0) {
                mCallbacks.notifySessionActiveChanged(session.sessionId, session.userId,
                        active);
            }
        }

        public void onSessionProgressChanged(PackageInstallerSession session, float progress) {
            if ((session.params.installFlags & PackageManager.INSTALL_DRY_RUN) == 0) {
                mCallbacks.notifySessionProgressChanged(session.sessionId, session.userId,
                        progress);
            }
        }

        public void onStagedSessionChanged(PackageInstallerSession session) {
            session.markUpdated();
            writeSessionsAsync();
            if (mOkToSendBroadcasts) {
                mPm.sendSessionUpdatedBroadcast(session.generateInfo(false),
                        session.userId);
            }
        }

        public void onSessionFinished(final PackageInstallerSession session, boolean success) {
            if ((session.params.installFlags & PackageManager.INSTALL_DRY_RUN) == 0) {
                mCallbacks.notifySessionFinished(session.sessionId, session.userId, success);
            }

            mInstallHandler.post(new Runnable() {
                @Override
                public void run() {
                    if (session.isStaged()) {
                        if (!success) {
                            mStagingManager.abortSession(session);
                        }
                    }
                    synchronized (mSessions) {
                        if (!session.isStaged() || !success) {
                            mSessions.remove(session.sessionId);
                        }
                        addHistoricalSessionLocked(session);

                        final File appIconFile = buildAppIconFile(session.sessionId);
                        if (appIconFile.exists()) {
                            appIconFile.delete();
                        }

                        writeSessionsLocked();
                    }
                }
            });
        }

        public void onSessionPrepared(PackageInstallerSession session) {
            // We prepared the destination to write into; we want to persist
            // this, but it's not critical enough to block for.
            writeSessionsAsync();
        }

        public void onSessionSealedBlocking(PackageInstallerSession session) {
            // It's very important that we block until we've recorded the
            // session as being sealed, since we never want to allow mutation
            // after sealing.
            synchronized (mSessions) {
                writeSessionsLocked();
            }
        }
    }
}