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Commit 57640fab authored by Ruslan Tkhakokhov's avatar Ruslan Tkhakokhov
Browse files

Remove default home app backup from @pm@ 

Currently @pm@ backs up information about the home app (launcher) chosen
as the default on the device. This data is not used anywhere on restore
(see linked bug for details).

Remove the redundant backup logic but keep the restore code to correctly
process old backups.

Bug: 123552771
Test: atest CtsBackupTestCases
      atest CtsBackupHostTestCases
      atest GtsBackupTestCases
      atest GtsBackupHostTestCases
Change-Id: Ib6c69357b2a68062c0abd1e6443f6e632070b776
parent 6eba9508

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

+4 −64
Original line number Diff line number Diff line
@@ -235,60 +235,7 @@ public class PackageManagerBackupAgent extends BackupAgent { 
            return;

        }



        long homeVersion = 0;

        ArrayList<byte[]> homeSigHashes = null;

        PackageInfo homeInfo = null;

        String homeInstaller = null;

        ComponentName home = getPreferredHomeComponent();

        if (home != null) {

        try {

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

                        PackageManager.GET_SIGNING_CERTIFICATES, mUserId);

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

                homeVersion = homeInfo.getLongVersionCode();

                SigningInfo signingInfo = homeInfo.signingInfo;

                if (signingInfo == null) {

                    Slog.e(TAG, "Home app has no signing information");

                } else {

                    // retrieve the newest sigs to back up

                    // TODO (b/73988180) use entire signing history in case of rollbacks

                    Signature[] homeInfoSignatures = signingInfo.getApkContentsSigners();

                    homeSigHashes = BackupUtils.hashSignatureArray(homeInfoSignatures);

                }

            } 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.

            PackageManagerInternal pmi = LocalServices.getService(PackageManagerInternal.class);

            final boolean needHomeBackup = (homeVersion != mStoredHomeVersion)

                    || !Objects.equals(home, mStoredHomeComponent)

                    || (home != null

                        && !BackupUtils.signaturesMatch(mStoredHomeSigHashes, homeInfo, pmi));

            if (needHomeBackup) {

                if (DEBUG) {

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

                }

                if (home != null) {

                    outputBuffer.reset();

                    outputBufferStream.writeUTF(home.flattenToString());

                    outputBufferStream.writeLong(homeVersion);

                    outputBufferStream.writeUTF(homeInstaller != null ? homeInstaller : "" );

                    writeSignatureHashArray(outputBufferStream, homeSigHashes);

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

                } else {

                    data.writeEntityHeader(DEFAULT_HOME_KEY, -1);

                }

            }



            /*

             * Global metadata:

             *
@@ -403,7 +350,7 @@ public class PackageManagerBackupAgent extends BackupAgent { 
        }



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

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

        writeStateFile(mAllPackages, newState);

    }



    private static void writeEntity(BackupDataOutput data, String key, byte[] bytes)
@@ -623,8 +570,7 @@ public class PackageManagerBackupAgent extends BackupAgent { 
    }



    // Util: write out our new backup state file

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

            long homeVersion, ArrayList<byte[]> homeSigHashes, ParcelFileDescriptor stateFile) {

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

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

        BufferedOutputStream outbuf = new BufferedOutputStream(outstream);

        DataOutputStream out = new DataOutputStream(outbuf);
@@ -635,14 +581,6 @@ public class PackageManagerBackupAgent extends BackupAgent { 
            out.writeUTF(STATE_FILE_HEADER);

            out.writeInt(STATE_FILE_VERSION);



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

            if (preferredHome != null) {

                out.writeUTF(DEFAULT_HOME_KEY);

                out.writeUTF(preferredHome.flattenToString());

                out.writeLong(homeVersion);

                writeSignatureHashArray(out, homeSigHashes);

            }



            // Conclude with the metadata block

            out.writeUTF(GLOBAL_METADATA_KEY);

            out.writeInt(Build.VERSION.SDK_INT);
@@ -789,6 +727,8 @@ public class PackageManagerBackupAgent extends BackupAgent { 
                                + Build.VERSION.INCREMENTAL + ")");

                    }

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

                    // Default home app data is no longer backed up by this agent. This code is

                    // kept to handle restore of old backups that still contain home app data.

                    String cn = inputBufferStream.readUTF();

                    mRestoredHome = ComponentName.unflattenFromString(cn);

                    mRestoredHomeVersion = inputBufferStream.readLong();