Add more error checking to xml restore

Bad files and OS updates can cause the restore to throw an NPE.
Rather than bring down the server process over this, just delete
the persistent file and keep going.

Fixes bug 15219594.

Change-Id: Id9cd39988ff93a26def036a05c46209364f2a4c0

services/core/java/com/android/server/am/ActivityRecord.java

@@ -1154,13 +1154,15 @@ final class ActivityRecord {
         }
 
         if (intent == null) {
-            Slog.e(TAG, "restoreActivity error intent=" + intent);
-            return null;
+            throw new XmlPullParserException("restoreActivity error intent=" + intent);
         }
 
         final ActivityManagerService service = stackSupervisor.mService;
         final ActivityInfo aInfo = stackSupervisor.resolveActivity(intent, resolvedType, 0, null,
                 null, userId);
+        if (aInfo == null) {
+            throw new XmlPullParserException("restoreActivity resolver error.");
+        }
         final ActivityRecord r = new ActivityRecord(service, /*caller*/null, launchedFromUid,
                 launchedFromPackage, intent, resolvedType, aInfo, service.getConfiguration(),
                 null, null, 0, componentSpecified, stackSupervisor, null, null);

services/core/java/com/android/server/am/TaskPersister.java

@@ -155,6 +155,7 @@ public class TaskPersister {
             File taskFile = recentFiles[taskNdx];
             if (DEBUG) Slog.d(TAG, "restoreTasksLocked: taskFile=" + taskFile.getName());
             BufferedReader reader = null;
+            boolean deleteFile = false;
             try {
                 reader = new BufferedReader(new FileReader(taskFile));
                 final XmlPullParser in = Xml.newPullParser();
@@ -183,10 +184,9 @@ public class TaskPersister {
                     }
                     XmlUtils.skipCurrentTag(in);
                 }
-            } catch (IOException e) {
-                Slog.e(TAG, "Unable to parse " + taskFile + ". Error " + e);
-            } catch (XmlPullParserException e) {
-                Slog.e(TAG, "Unable to parse " + taskFile + ". Error " + e);
+            } catch (Exception e) {
+                Slog.wtf(TAG, "Unable to parse " + taskFile + ". Error " + e);
+                deleteFile = true;
             } finally {
                 if (reader != null) {
                     try {
@@ -194,6 +194,9 @@ public class TaskPersister {
                     } catch (IOException e) {
                     }
                 }
+                if (!DEBUG && deleteFile) {
+                    taskFile.delete();
+                }
             }
         }
 
@@ -220,7 +223,7 @@ public class TaskPersister {
         return new ArrayList<TaskRecord>(Arrays.asList(tasksArray));
     }
 
-    private void removeObsoleteFiles(ArraySet<Integer> persistentTaskIds, File[] files) {
+    private static void removeObsoleteFiles(ArraySet<Integer> persistentTaskIds, File[] files) {
         for (int fileNdx = 0; fileNdx < files.length; ++fileNdx) {
             File file = files[fileNdx];
             String filename = file.getName();
@@ -285,8 +288,7 @@ public class TaskPersister {
                 synchronized(mService) {
                     final ArrayList<TaskRecord> tasks = mService.mRecentTasks;
                     persistentTaskIds.clear();
-                    int taskNdx;
-                    for (taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
+                    for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
                         task = tasks.get(taskNdx);
                         if (DEBUG) Slog.d(TAG, "LazyTaskWriter: task=" + task + " persistable=" +
                                 task.isPersistable + " needsPersisting=" + task.needsPersisting);