Only restore the bits for wallpapers that aren't built in.
diff --git a/services/java/com/android/server/JournaledFile.java b/services/java/com/android/server/JournaledFile.java
new file mode 100644
index 0000000..3d1f52d
--- /dev/null
+++ b/services/java/com/android/server/JournaledFile.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2009 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;
+
+import java.io.File;
+import java.io.IOException;
+
+public class JournaledFile {
+ File mReal;
+ File mTemp;
+ boolean mWriting;
+
+ public JournaledFile(File real, File temp) {
+ mReal = real;
+ mTemp = temp;
+ }
+
+ /** Returns the file for you to read.
+ * @more
+ * Prefers the real file. If it doesn't exist, uses the temp one, and then copies
+ * it to the real one. If there is both a real file and a temp one, assumes that the
+ * temp one isn't fully written and deletes it.
+ */
+ public File chooseForRead() {
+ File result;
+ if (mReal.exists()) {
+ result = mReal;
+ if (mTemp.exists()) {
+ mTemp.delete();
+ }
+ } else if (mTemp.exists()) {
+ result = mTemp;
+ mTemp.renameTo(mReal);
+ } else {
+ return mReal;
+ }
+ return result;
+ }
+
+ /**
+ * Returns a file for you to write.
+ * @more
+ * If a write is already happening, throws. In other words, you must provide your
+ * own locking.
+ * <p>
+ * Call {@link #commit} to commit the changes, or {@link #rollback} to forget the changes.
+ */
+ public File chooseForWrite() {
+ if (mWriting) {
+ throw new IllegalStateException("uncommitted write already in progress");
+ }
+ if (!mReal.exists()) {
+ // If the real one doesn't exist, it's either because this is the first time
+ // or because something went wrong while copying them. In this case, we can't
+ // trust anything that's in temp. In order to have the chooseForRead code not
+ // use the temporary one until it's fully written, create an empty file
+ // for real, which will we'll shortly delete.
+ try {
+ mReal.createNewFile();
+ } catch (IOException e) {
+ // Ignore
+ }
+ }
+
+ if (mTemp.exists()) {
+ mTemp.delete();
+ }
+ mWriting = true;
+ return mTemp;
+ }
+
+ /**
+ * Commit changes.
+ */
+ public void commit() {
+ if (!mWriting) {
+ throw new IllegalStateException("no file to commit");
+ }
+ mWriting = false;
+ mTemp.renameTo(mReal);
+ }
+
+ /**
+ * Roll back changes.
+ */
+ public void rollback() {
+ if (!mWriting) {
+ throw new IllegalStateException("no file to roll back");
+ }
+ mWriting = false;
+ mTemp.delete();
+ }
+}