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Commit fe2368c3 authored by Christopher Tate's avatar Christopher Tate
Browse files

Refresh in-memory SharedPreferences instances after restore 

Existing instances don't know that the file has changed out from
under them, so they continue to return stale values from reads, and
risk overwriting restored data with stale content if writes are
performed.  We now tell the backing cache system to induce a
reload after restore (i.e. after we might have written a relevant
file out from under it).

Along the way we shook out an irregularity in the way we were
setting up the context topology of non-lifecycle instances of
the metadata-handling BackupAgent subclass, so that's fixed
now too.

Bug 12061817
Test: cts-tradefed run cts -m CtsBackupHostTestCases

Change-Id: I401fe9297235b55d8a8f041e430d122dc6e24129
parent 1bd58ef4

core/java/android/app/ContextImpl.java

+21 −0
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ import java.io.FilenameFilter; 
import java.io.IOException;

import java.io.InputStream;

import java.nio.ByteOrder;

import java.util.ArrayList;

import java.util.Objects;



class ReceiverRestrictedContext extends ContextWrapper {
@@ -417,6 +418,26 @@ class ContextImpl extends Context { 
        return packagePrefs;

    }



    @Override

    public void reloadSharedPreferences() {

        // Build the list of all per-context impls (i.e. caches) we know about

        ArrayList<SharedPreferencesImpl> spImpls = new ArrayList<>();

        synchronized (ContextImpl.class) {

            final ArrayMap<File, SharedPreferencesImpl> cache = getSharedPreferencesCacheLocked();

            for (int i = 0; i < cache.size(); i++) {

                final SharedPreferencesImpl sp = cache.valueAt(i);

                if (sp != null) {

                    spImpls.add(sp);

                }

            }

        }



        // Issue the reload outside the cache lock

        for (int i = 0; i < spImpls.size(); i++) {

            spImpls.get(i).startReloadIfChangedUnexpectedly();

        }

    }



    /**

     * Try our best to migrate all files from source to target that match

     * requested prefix.

core/java/android/app/backup/BackupAgent.java

+9 −2
Original line number Diff line number Diff line
@@ -942,6 +942,11 @@ public abstract class BackupAgent extends ContextWrapper { 
            long ident = Binder.clearCallingIdentity();



            if (DEBUG) Log.v(TAG, "doRestore() invoked");



            // Ensure that any side-effect SharedPreferences writes have landed *before*

            // we may be about to rewrite the file out from underneath

            waitForSharedPrefs();



            BackupDataInput input = new BackupDataInput(data.getFileDescriptor());

            try {

                BackupAgent.this.onRestore(input, appVersionCode, newState);
@@ -952,8 +957,8 @@ public abstract class BackupAgent extends ContextWrapper { 
                Log.d(TAG, "onRestore (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                throw ex;

            } finally {

                // Ensure that any side-effect SharedPreferences writes have landed

                waitForSharedPrefs();

                // And bring live SharedPreferences instances up to date

                reloadSharedPreferences();



                Binder.restoreCallingIdentity(ident);

                try {
@@ -1053,6 +1058,8 @@ public abstract class BackupAgent extends ContextWrapper { 
            } finally {

                // Ensure that any side-effect SharedPreferences writes have landed

                waitForSharedPrefs();

                // And bring live SharedPreferences instances up to date

                reloadSharedPreferences();



                Binder.restoreCallingIdentity(ident);

                try {

core/java/android/content/Context.java

+3 −0
Original line number Diff line number Diff line
@@ -813,6 +813,9 @@ public abstract class Context { 
     */

    public abstract boolean deleteSharedPreferences(String name);



    /** @hide */

    public abstract void reloadSharedPreferences();



    /**

     * Open a private file associated with this Context's application package

     * for reading.

core/java/android/content/ContextWrapper.java

+6 −1
Original line number Diff line number Diff line
@@ -19,7 +19,6 @@ package android.content; 
import android.annotation.SystemApi;

import android.app.IApplicationThread;

import android.app.IServiceConnection;

import android.app.Notification;

import android.content.pm.ApplicationInfo;

import android.content.pm.PackageManager;

import android.content.res.AssetManager;
@@ -173,6 +172,12 @@ public class ContextWrapper extends Context { 
        return mBase.getSharedPreferences(file, mode);

    }



    /** @hide */

    @Override

    public void reloadSharedPreferences() {

        mBase.reloadSharedPreferences();

    }



    @Override

    public boolean moveSharedPreferencesFrom(Context sourceContext, String name) {

        return mBase.moveSharedPreferencesFrom(sourceContext, name);

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

+26 −4
Original line number Diff line number Diff line
@@ -839,6 +839,29 @@ public class BackupManagerService implements BackupManagerServiceInterface { 
        return !appGetsFullBackup(pkg);

    }













    /*













     * Construct a backup agent instance for the metadata pseudopackage.  This is a













     * process-local non-lifecycle agent instance, so we manually set up the context













     * topology for it.













     */













    PackageManagerBackupAgent makeMetadataAgent() {













        PackageManagerBackupAgent pmAgent = new PackageManagerBackupAgent(mPackageManager);













        pmAgent.attach(mContext);













        pmAgent.onCreate();













        return pmAgent;













    }

























    /*













     * Same as above but with the explicit package-set configuration.













     */













    PackageManagerBackupAgent makeMetadataAgent(List<PackageInfo> packages) {













        PackageManagerBackupAgent pmAgent =













                new PackageManagerBackupAgent(mPackageManager, packages);













        pmAgent.attach(mContext);













        pmAgent.onCreate();













        return pmAgent;













    }



























    // ----- Asynchronous backup/restore handler thread -----





























    private class BackupHandler extends Handler {










@@ -2893,8 +2916,7 @@ public class BackupManagerService implements BackupManagerServiceInterface {













                    // because it's cheap and this way we guarantee that we don't get out of















                    // step even if we're selecting among various transports at run time.















                    if (mStatus == BackupTransport.TRANSPORT_OK) {













                        PackageManagerBackupAgent pmAgent = new PackageManagerBackupAgent(













                                mPackageManager);













                        PackageManagerBackupAgent pmAgent = makeMetadataAgent();















                        mStatus = invokeAgentForBackup(PACKAGE_MANAGER_SENTINEL,















                                IBackupAgent.Stub.asInterface(pmAgent.onBind()), mTransport);















                        addBackupTrace("PMBA invoke: " + mStatus);










@@ -7155,7 +7177,7 @@ if (MORE_DEBUG) Slog.v(TAG, "   + got " + nRead + "; now wanting " + (size - soF













            mObserver = observer;















            mLatchObject = latch;















            mAgent = null;













            mPackageManagerBackupAgent = new PackageManagerBackupAgent(mPackageManager);













            mPackageManagerBackupAgent = makeMetadataAgent();















            mAgentPackage = null;















            mTargetApp = null;















            mObbConnection = new FullBackupObbConnection();










@@ -8817,7 +8839,7 @@ if (MORE_DEBUG) Slog.v(TAG, "   + got " + nRead + "; now wanting " + (size - soF













                // Pull the Package Manager metadata from the restore set first















                mCurrentPackage = new PackageInfo();















                mCurrentPackage.packageName = PACKAGE_MANAGER_SENTINEL;













                mPmAgent = new PackageManagerBackupAgent(mPackageManager, null);













                mPmAgent = makeMetadataAgent(null);















                mAgent = IBackupAgent.Stub.asInterface(mPmAgent.onBind());















                if (MORE_DEBUG) {















                    Slog.v(TAG, "initiating restore for PMBA");