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Commit a99d0217 authored by Christopher Tate's avatar Christopher Tate
Browse files

Back up the preferred home app, if any 

If the user has stated a preference about their home app, make sure we
capture that so that a system restore can return them to that preferred
situation.  It's built into the system metadata so that we can, if
necessary, fast-path configuration of that home app while the rest of
the restore operation is in flight.

Change-Id: I64dfee8f7a2a9e40f556cd19298d7b367c6aa8dc
parent 118d1134

services/backup/java/com/android/server/backup/BackupManagerService.java

+5 −1
Original line number Diff line number Diff line
@@ -4690,7 +4690,11 @@ public class BackupManagerService extends IBackupManager.Stub { 


    // ----- Restore handling -----



    private boolean signaturesMatch(Signature[] storedSigs, PackageInfo target) {

    static boolean signaturesMatch(Signature[] storedSigs, PackageInfo target) {

        if (target == null) {

            return false;

        }



        // If the target resides on the system partition, we allow it to restore

        // data from the like-named package in a restore set even if the signatures

        // do not match.  (Unlike general applications, those flashed to the system

services/backup/java/com/android/server/backup/PackageManagerBackupAgent.java

+115 −9
Original line number Diff line number Diff line
@@ -19,15 +19,19 @@ package com.android.server.backup; 
import android.app.backup.BackupAgent;

import android.app.backup.BackupDataInput;

import android.app.backup.BackupDataOutput;

import android.content.ComponentName;

import android.content.pm.ApplicationInfo;

import android.content.pm.PackageInfo;

import android.content.pm.PackageManager;

import android.content.pm.ResolveInfo;

import android.content.pm.PackageManager.NameNotFoundException;

import android.content.pm.Signature;

import android.os.Build;

import android.os.ParcelFileDescriptor;

import android.util.Slog;



import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.DataInputStream;
@@ -42,6 +46,8 @@ import java.util.HashSet; 
import java.util.List;

import java.util.Set;



import java.util.Objects;



/**

 * We back up the signatures of each package so that during a system restore,

 * we can verify that the app whose data we think we have matches the app
@@ -58,6 +64,9 @@ public class PackageManagerBackupAgent extends BackupAgent { 
    // is stored using the package name as a key)

    private static final String GLOBAL_METADATA_KEY = "@meta@";



    // key under which we store the identity of the user's chosen default home app

    private static final String DEFAULT_HOME_KEY = "@home@";



    private List<PackageInfo> mAllPackages;

    private PackageManager mPackageManager;

    // version & signature info of each app in a restore set
@@ -68,7 +77,15 @@ public class PackageManagerBackupAgent extends BackupAgent { 
    private final HashSet<String> mExisting = new HashSet<String>();

    private int mStoredSdkVersion;

    private String mStoredIncrementalVersion;

    private ComponentName mStoredHomeComponent;

    private long mStoredHomeVersion;

    private Signature[] mStoredHomeSigs;



    private boolean mHasMetadata;

    private ComponentName mRestoredHome;

    private long mRestoredHomeVersion;

    private String mRestoredHomeInstaller;

    private Signature[] mRestoredHomeSignatures;



    public class Metadata {

        public int versionCode;
@@ -136,7 +153,50 @@ public class PackageManagerBackupAgent extends BackupAgent { 
            mExisting.clear();

        }



        long homeVersion = 0;

        Signature[] homeSigs = null;

        PackageInfo homeInfo = null;

        String homeInstaller = null;

        ComponentName home = getPreferredHomeComponent();

        if (home != null) {

            try {

                homeInfo = mPackageManager.getPackageInfo(home.getPackageName(),

                        PackageManager.GET_SIGNATURES);

                homeInstaller = mPackageManager.getInstallerPackageName(home.getPackageName());

                homeVersion = homeInfo.versionCode;

                homeSigs = homeInfo.signatures;

            } catch (NameNotFoundException e) {

                Slog.w(TAG, "Can't access preferred home info");

                // proceed as though there were no preferred home set

                home = null;

            }

        }



        try {

            // We need to push a new preferred-home-app record if:

            //    1. the version of the home app has changed since our last backup;

            //    2. the home app [or absence] we now use differs from the prior state,

            // OR 3. it looks like we use the same home app + version as before, but

            //       the signatures don't match so we treat them as different apps.

            final boolean needHomeBackup = (homeVersion != mStoredHomeVersion)

                    || Objects.equals(home, mStoredHomeComponent)

                    || (home != null

                        && !BackupManagerService.signaturesMatch(mStoredHomeSigs, homeInfo));

            if (needHomeBackup) {

                if (DEBUG) {

                    Slog.i(TAG, "Home preference changed; backing up new state " + home);

                }

                if (home != null) {

                    outputBufferStream.writeUTF(home.flattenToString());

                    outputBufferStream.writeLong(homeVersion);

                    outputBufferStream.writeUTF(homeInstaller);

                    writeSignatureArray(outputBufferStream, homeSigs);

                    writeEntity(data, DEFAULT_HOME_KEY, outputBuffer.toByteArray());

                } else {

                    data.writeEntityHeader(DEFAULT_HOME_KEY, -1);

                }

            }



            /*

             * Global metadata:

             *
@@ -146,6 +206,7 @@ public class PackageManagerBackupAgent extends BackupAgent { 
             * String incremental -- the incremental release name of the OS stored in

             *                       the backup set.

             */

            outputBuffer.reset();

            if (!mExisting.contains(GLOBAL_METADATA_KEY)) {

                if (DEBUG) Slog.v(TAG, "Storing global metadata key");

                outputBufferStream.writeInt(Build.VERSION.SDK_INT);
@@ -238,7 +299,7 @@ public class PackageManagerBackupAgent extends BackupAgent { 
        }



        // Finally, write the new state blob -- just the list of all apps we handled

        writeStateFile(mAllPackages, newState);

        writeStateFile(mAllPackages, home, homeVersion, homeSigs, newState);

    }

    

    private static void writeEntity(BackupDataOutput data, String key, byte[] bytes)
@@ -286,6 +347,19 @@ public class PackageManagerBackupAgent extends BackupAgent { 
                            + " (" + mStoredIncrementalVersion + " vs "

                            + Build.VERSION.INCREMENTAL + ")");

                }

            } else if (key.equals(DEFAULT_HOME_KEY)) {

                String cn = inputBufferStream.readUTF();

                mRestoredHome = ComponentName.unflattenFromString(cn);

                mRestoredHomeVersion = inputBufferStream.readLong();

                mRestoredHomeInstaller = inputBufferStream.readUTF();

                mRestoredHomeSignatures = readSignatureArray(inputBufferStream);

                if (DEBUG) {

                    Slog.i(TAG, "   read preferred home app " + mRestoredHome

                            + " version=" + mRestoredHomeVersion

                            + " installer=" + mRestoredHomeVersion

                            + " sig=" + mRestoredHomeVersion);

                }



            } else {

                // it's a file metadata record

                int versionCode = inputBufferStream.readInt();
@@ -365,18 +439,34 @@ public class PackageManagerBackupAgent extends BackupAgent { 
        mStateVersions.clear();

        mStoredSdkVersion = 0;

        mStoredIncrementalVersion = null;

        mStoredHomeComponent = null;

        mStoredHomeVersion = 0;

        mStoredHomeSigs = null;



        // The state file is just the list of app names we have stored signatures for

        // with the exception of the metadata block, to which is also appended the

        // version numbers corresponding with the last time we wrote this PM block.

        // If they mismatch the current system, we'll re-store the metadata key.

        FileInputStream instream = new FileInputStream(stateFile.getFileDescriptor());

        DataInputStream in = new DataInputStream(instream);

        BufferedInputStream inbuffer = new BufferedInputStream(instream);

        DataInputStream in = new DataInputStream(inbuffer);



        int bufSize = 256;

        byte[] buf = new byte[bufSize];

        try {

            String pkg = in.readUTF();



            // First comes the preferred home app data, if any, headed by the DEFAULT_HOME_KEY tag

            if (pkg.equals(DEFAULT_HOME_KEY)) {

                // flattened component name, version, signature of the home app

                mStoredHomeComponent = ComponentName.unflattenFromString(in.readUTF());

                mStoredHomeVersion = in.readLong();

                mStoredHomeSigs = readSignatureArray(in);



                pkg = in.readUTF(); // set up for the next block of state

            } else {

                // else no preferred home app on the ancestral device - fall through to the rest

            }



            // After (possible) home app data comes the global metadata block

            if (pkg.equals(GLOBAL_METADATA_KEY)) {

                mStoredSdkVersion = in.readInt();

                mStoredIncrementalVersion = in.readUTF();
@@ -386,7 +476,7 @@ public class PackageManagerBackupAgent extends BackupAgent { 
                return;

            }



            // The global metadata was first; now read all the apps

            // The global metadata was last; now read all the apps

            while (true) {

                pkg = in.readUTF();

                int versionCode = in.readInt();
@@ -401,13 +491,28 @@ public class PackageManagerBackupAgent extends BackupAgent { 
        }

    }



    private ComponentName getPreferredHomeComponent() {

        return mPackageManager.getHomeActivities(new ArrayList<ResolveInfo>());

    }



    // Util: write out our new backup state file

    private void writeStateFile(List<PackageInfo> pkgs, ParcelFileDescriptor stateFile) {

    private void writeStateFile(List<PackageInfo> pkgs, ComponentName preferredHome,

            long homeVersion, Signature[] homeSignatures, ParcelFileDescriptor stateFile) {

        FileOutputStream outstream = new FileOutputStream(stateFile.getFileDescriptor());

        DataOutputStream out = new DataOutputStream(outstream);

        BufferedOutputStream outbuf = new BufferedOutputStream(outstream);

        DataOutputStream out = new DataOutputStream(outbuf);



        // by the time we get here we know we've done all our backing up

        try {

            // by the time we get here we know we've stored the global metadata record

            // If we remembered a preferred home app, record that

            if (preferredHome != null) {

                out.writeUTF(DEFAULT_HOME_KEY);

                out.writeUTF(preferredHome.flattenToString());

                out.writeLong(homeVersion);

                writeSignatureArray(out, homeSignatures);

            }



            // Conclude with the metadata block

            out.writeUTF(GLOBAL_METADATA_KEY);

            out.writeInt(Build.VERSION.SDK_INT);

            out.writeUTF(Build.VERSION.INCREMENTAL);
@@ -417,9 +522,10 @@ public class PackageManagerBackupAgent extends BackupAgent { 
                out.writeUTF(pkg.packageName);

                out.writeInt(pkg.versionCode);

            }



            out.flush();

        } catch (IOException e) {

            Slog.e(TAG, "Unable to write package manager state file!");

            return;

        }

    }

}