null AssetFileDescriptors support added in `ContentDataSource`

library/core/src/androidTest/java/com/google/android/exoplayer2/upstream/AndroidDataSourceConstants.java

 package com.google.android.exoplayer2.upstream;
 package com.google.android.exoplayer2.upstream;
 
 
+import android.content.ContentResolver;
+import android.net.Uri;
+
 final class AndroidDataSourceConstants {
 final class AndroidDataSourceConstants {
   static final long SAMPLE_MP4_BYTES = 101597;
   static final long SAMPLE_MP4_BYTES = 101597;
   static final String SAMPLE_MP4_PATH = "/mp4/sample.mp4";
   static final String SAMPLE_MP4_PATH = "/mp4/sample.mp4";
+  static final String TEST_DATA_PROVIDER_AUTHORITY = "exoplayer";
+  static final Uri NULL_DESCRIPTOR_URI = new Uri.Builder()
+          .scheme(ContentResolver.SCHEME_CONTENT)
+          .authority(TEST_DATA_PROVIDER_AUTHORITY)
+          .build();
 
 
   private AndroidDataSourceConstants() {}
   private AndroidDataSourceConstants() {}
 }
 }

library/core/src/androidTest/java/com/google/android/exoplayer2/upstream/ContentDataSourceTest.java

 package com.google.android.exoplayer2.upstream;
 package com.google.android.exoplayer2.upstream;
 
 
+import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Context;
 import android.net.Uri;
 import android.net.Uri;
 import android.test.InstrumentationTestCase;
 import android.test.InstrumentationTestCase;
 
 
+import static com.google.android.exoplayer2.upstream.AndroidDataSourceConstants.NULL_DESCRIPTOR_URI;
 import static com.google.android.exoplayer2.upstream.AndroidDataSourceConstants.SAMPLE_MP4_BYTES;
 import static com.google.android.exoplayer2.upstream.AndroidDataSourceConstants.SAMPLE_MP4_BYTES;
 import static com.google.android.exoplayer2.upstream.AndroidDataSourceConstants.SAMPLE_MP4_PATH;
 import static com.google.android.exoplayer2.upstream.AndroidDataSourceConstants.SAMPLE_MP4_PATH;
+import static com.google.android.exoplayer2.upstream.AndroidDataSourceConstants.TEST_DATA_PROVIDER_AUTHORITY;
 
 
 public class ContentDataSourceTest extends InstrumentationTestCase {
 public class ContentDataSourceTest extends InstrumentationTestCase {
 
 
-  public void testContentDataSource() throws Exception {
+  public void testValidContentDataSource() throws Exception {
     Context context = getInstrumentation().getContext();
     Context context = getInstrumentation().getContext();
     ContentDataSource dataSource = new ContentDataSource(context);
     ContentDataSource dataSource = new ContentDataSource(context);
-    Uri contentUri = Uri.parse("content://exoplayer" + SAMPLE_MP4_PATH);
+    Uri contentUri = new Uri.Builder()
+            .scheme(ContentResolver.SCHEME_CONTENT)
+            .authority(TEST_DATA_PROVIDER_AUTHORITY)
+            .path(SAMPLE_MP4_PATH).build();
     DataSpec dataSpec = new DataSpec(contentUri);
     DataSpec dataSpec = new DataSpec(contentUri);
     long sourceLengthBytes = dataSource.open(dataSpec);
     long sourceLengthBytes = dataSource.open(dataSpec);
 
 
     assertEquals(SAMPLE_MP4_BYTES, sourceLengthBytes);
     assertEquals(SAMPLE_MP4_BYTES, sourceLengthBytes);
   }
   }
+
+  public void testNullContentDataSource() throws Exception {
+    Context context = getInstrumentation().getContext();
+    ContentDataSource dataSource = new ContentDataSource(context);
+    DataSpec dataSpec = new DataSpec(NULL_DESCRIPTOR_URI);
+
+    try {
+      dataSource.open(dataSpec);
+      fail("Expected exception not thrown.");
+    } catch (ContentDataSource.ContentDataSourceException e) {
+      // Expected.
+    }
+  }
 }
 }

library/core/src/androidTest/java/com/google/android/exoplayer2/upstream/TestDataProvider.java

@@ -29,6 +29,10 @@ public class TestDataProvider extends ContentProvider {
   @Nullable
   @Nullable
   @Override
   @Override
   public AssetFileDescriptor openAssetFile(@NonNull final Uri uri, @NonNull final String mode) throws FileNotFoundException {
   public AssetFileDescriptor openAssetFile(@NonNull final Uri uri, @NonNull final String mode) throws FileNotFoundException {
+    if (uri.equals(AndroidDataSourceConstants.NULL_DESCRIPTOR_URI)) {
+      return null;
+    }
+
     try {
     try {
       Context context = getContext();
       Context context = getContext();
       assertNotNull(context);
       assertNotNull(context);

library/core/src/main/java/com/google/android/exoplayer2/upstream/ContentDataSource.java

@@ -22,6 +22,7 @@ import android.net.Uri;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.C;
 import java.io.EOFException;
 import java.io.EOFException;
 import java.io.FileInputStream;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStream;
 
 
@@ -71,6 +72,9 @@ public final class ContentDataSource implements DataSource {
     try {
     try {
       uri = dataSpec.uri;
       uri = dataSpec.uri;
       assetFileDescriptor = resolver.openAssetFileDescriptor(uri, "r");
       assetFileDescriptor = resolver.openAssetFileDescriptor(uri, "r");
+      if (assetFileDescriptor == null) {
+        throw new FileNotFoundException("Could not open file descriptor for: " + uri);
+      }
       inputStream = new FileInputStream(assetFileDescriptor.getFileDescriptor());
       inputStream = new FileInputStream(assetFileDescriptor.getFileDescriptor());
       long skipped = inputStream.skip(dataSpec.position);
       long skipped = inputStream.skip(dataSpec.position);
       if (skipped < dataSpec.position) {
       if (skipped < dataSpec.position) {