Merge "Fix NPE while reading leftover journals in BMS"

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

@@ -17,6 +17,7 @@
 package com.android.server.backup;
 
 import android.annotation.Nullable;
+import android.util.Slog;
 
 import java.io.BufferedInputStream;
 import java.io.DataInputStream;
@@ -36,6 +37,7 @@ import java.util.function.Consumer;
  * reboot.
  */
 public class DataChangedJournal {
+    private static final String TAG = "DataChangedJournal";
     private static final String FILE_NAME_PREFIX = "journal";
 
     /**
@@ -139,7 +141,12 @@ public class DataChangedJournal {
      */
     static ArrayList<DataChangedJournal> listJournals(File journalDirectory) {
         ArrayList<DataChangedJournal> journals = new ArrayList<>();
-        for (File file : journalDirectory.listFiles()) {
+        File[] journalFiles = journalDirectory.listFiles();
+        if (journalFiles == null) {
+            Slog.w(TAG, "Failed to read journal files");
+            return journals;
+        }
+        for (File file : journalFiles) {
             journals.add(new DataChangedJournal(file));
         }
         return journals;

services/tests/servicestests/src/com/android/server/backup/DataChangedJournalTest.java

@@ -18,6 +18,9 @@ package com.android.server.backup;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import static org.mockito.Mockito.when;
+import static org.testng.Assert.assertEquals;
+
 import android.platform.test.annotations.Presubmit;
 
 import androidx.test.filters.SmallTest;
@@ -50,6 +53,7 @@ public class DataChangedJournalTest {
     @Rule public TemporaryFolder mTemporaryFolder = new TemporaryFolder();
 
     @Mock private Consumer<String> mConsumer;
+    @Mock private File invalidFile;
 
     private File mFile;
     private DataChangedJournal mJournal;
@@ -131,4 +135,10 @@ public class DataChangedJournalTest {
     public void toString_isSameAsFileToString() throws Exception {
         assertThat(mJournal.toString()).isEqualTo(mFile.toString());
     }
+
+    public void listJournals_invalidJournalFile_returnsEmptyList() throws Exception {
+        when(invalidFile.listFiles()).thenReturn(null);
+
+        assertEquals(0, DataChangedJournal.listJournals(invalidFile).size());
+    }
 }