Fix Settings writes to a different user

Oops.  Stacked bugs:  first, the desired user handle was not properly
being passed from the call() entry point to the database operations;
then on top of that, the client-side cache management was still
looking in the local user's cache for the data, so a request to read
a different user's settings would return the local user's instead if
that key was already known to the local user's cache.

Reads and writes of a different user's settings are now uncached,
so they're relatively much slower.  They're rare, however, so this
is not something to worry about unless we encounter a real world
case where it's a significant factor.

This CL also adds a bit of cross-user settings read/write testing
to the existing provider suite.  These new tests caught both the
known wrong-user-write bug and discovered the client-side cache
bug, so yay.

Finally, the existing wholesale mutual-exclusion approach would
deadlock in certain circumstances due to the fact that the
settings database creation code might have to call out to the
Package Manager while populating the bookmark/shortcut table,
and the Package Manager would then call back into the settings
provider in the course of handling that request.  The synchronization
regime has been significantly tightened up now: now the database
code [which is known to deal with concurrency itself] is allowed
to cope with multiple parallel openers of the same db; this
allows the settings provider to avoid calling out to other parts
of the system even implicitly while its internal lock is held.

Change-Id: Ib77d445b4a2ec658cc5c210830f6977c981f87ed

Author: Christopher Tate

core/java/android/provider/Settings.java

@@ -754,22 +754,29 @@ public boolean putString(ContentResolver cr, String name, String value) {
         }
 
         public String getStringForUser(ContentResolver cr, String name, final int userHandle) {
-            long newValuesVersion = SystemProperties.getLong(mVersionSystemProperty, 0);
+            final boolean isSelf = (userHandle == UserHandle.myUserId());
+            if (isSelf) {
+                long newValuesVersion = SystemProperties.getLong(mVersionSystemProperty, 0);
 
-            synchronized (this) {
-                if (mValuesVersion != newValuesVersion) {
-                    if (LOCAL_LOGV || false) {
-                        Log.v(TAG, "invalidate [" + mUri.getLastPathSegment() + "]: current " +
-                                newValuesVersion + " != cached " + mValuesVersion);
-                    }
+                // Our own user's settings data uses a client-side cache
+                synchronized (this) {
+                    if (mValuesVersion != newValuesVersion) {
+                        if (LOCAL_LOGV || false) {
+                            Log.v(TAG, "invalidate [" + mUri.getLastPathSegment() + "]: current "
+                                    + newValuesVersion + " != cached " + mValuesVersion);
+                        }
 
-                    mValues.clear();
-                    mValuesVersion = newValuesVersion;
-                }
+                        mValues.clear();
+                        mValuesVersion = newValuesVersion;
+                    }
 
-                if (mValues.containsKey(name)) {
-                    return mValues.get(name);  // Could be null, that's OK -- negative caching
+                    if (mValues.containsKey(name)) {
+                        return mValues.get(name);  // Could be null, that's OK -- negative caching
+                    }
                 }
+            } else {
+                if (LOCAL_LOGV) Log.v(TAG, "get setting for user " + userHandle
+                        + " by user " + UserHandle.myUserId() + " so skipping cache");
             }
 
             IContentProvider cp = lazyGetProvider(cr);
@@ -788,8 +795,15 @@ public String getStringForUser(ContentResolver cr, String name, final int userHa
                     Bundle b = cp.call(mCallGetCommand, name, args);
                     if (b != null) {
                         String value = b.getPairValue();
-                        synchronized (this) {
-                            mValues.put(name, value);
+                        // Don't update our cache for reads of other users' data
+                        if (isSelf) {
+                            synchronized (this) {
+                                mValues.put(name, value);
+                            }
+                        } else {
+                            if (LOCAL_LOGV) Log.i(TAG, "call-query of user " + userHandle
+                                    + " by " + UserHandle.myUserId()
+                                    + " so not updating cache");
                         }
                         return value;
                     }

core/tests/coretests/AndroidManifest.xml

@@ -69,6 +69,10 @@
     <uses-permission android:name="com.google.android.googleapps.permission.GOOGLE_AUTH" />
     <uses-permission android:name="com.google.android.googleapps.permission.GOOGLE_AUTH.ALL_SERVICES" />
 
+    <uses-permission android:name="android.permission.MANAGE_USERS" />
+    <uses-permission android:name="android.permission.INTERACT_ACROSS_USERS" />
+    <uses-permission android:name="android.permission.INTERACT_ACROSS_USERS_FULL" />
+
     <uses-permission android:name="android.permission.RECEIVE_SMS"/>
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.READ_CONTACTS" />

core/tests/coretests/src/android/provider/SettingsProviderTest.java

@@ -19,11 +19,15 @@
 import android.content.ContentResolver;
 import android.content.ContentUris;
 import android.content.ContentValues;
+import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
+import android.content.pm.UserInfo;
 import android.database.Cursor;
 import android.net.Uri;
+import android.os.UserHandle;
+import android.os.UserManager;
 import android.provider.Settings;
 import android.test.AndroidTestCase;
 import android.test.suitebuilder.annotation.MediumTest;
@@ -197,6 +201,53 @@ public void testParseProviderList() {
                 Settings.Secure.getString(r, Settings.Secure.LOCATION_PROVIDERS_ALLOWED));
      }
 
+    private boolean findUser(UserManager um, int userHandle) {
+        for (UserInfo user : um.getUsers()) {
+            if (user.id == userHandle) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @MediumTest
+    public void testPerUserSettings() {
+        UserManager um = (UserManager) getContext().getSystemService(Context.USER_SERVICE);
+        ContentResolver r = getContext().getContentResolver();
+
+        // Make sure there's an owner
+        assertTrue(findUser(um, UserHandle.USER_OWNER));
+
+        // create a new user to use for testing
+        UserInfo user = um.createUser("TestUser1", UserInfo.FLAG_GUEST);
+        assertTrue(user != null);
+
+        try {
+            // Write some settings for that user as well as the current user
+            final String TEST_KEY = "test_setting";
+            final int SELF_VALUE = 40;
+            final int OTHER_VALUE = 27;
+
+            Settings.System.putInt(r, TEST_KEY, SELF_VALUE);
+            Settings.System.putIntForUser(r, TEST_KEY, OTHER_VALUE, user.id);
+
+            // Verify that they read back as intended
+            int myValue = Settings.System.getInt(r, TEST_KEY, 0);
+            int otherValue = Settings.System.getIntForUser(r, TEST_KEY, 0, user.id);
+            assertTrue("Running as user " + UserHandle.myUserId()
+                    + " and reading/writing as user " + user.id
+                    + ", expected to read " + SELF_VALUE + " but got " + myValue,
+                    myValue == SELF_VALUE);
+            assertTrue("Running as user " + UserHandle.myUserId()
+                    + " and reading/writing as user " + user.id
+                    + ", expected to read " + OTHER_VALUE + " but got " + otherValue,
+                    otherValue == OTHER_VALUE);
+        } finally {
+            // Tidy up
+            um.removeUser(user.id);
+        }
+    }
+
      @SmallTest
      public void testSettings() {
         assertCanBeHandled(new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS));