Add to/from disk stable format

This change adds a utility to convert persistable bundles to and from
disk-stable byte arrays.

Test: atest FrameworksVcnTests:PersistableBundleUtilsTest
Change-Id: Ifafb7081ec6a34ce3ab8e2aa502d46411405cb6d

services/core/java/com/android/server/vcn/util/PersistableBundleUtils.java

@@ -23,6 +23,8 @@ import android.os.PersistableBundle;
 
 import com.android.internal.util.HexDump;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
@@ -295,6 +297,30 @@ public class PersistableBundleUtils {
         return result;
     }
 
+    /**
+     * Converts a PersistableBundle into a disk-stable byte array format
+     *
+     * @param bundle the PersistableBundle to be converted to a disk-stable format
+     * @return the byte array representation of the PersistableBundle
+     */
+    @Nullable
+    public static byte[] toDiskStableBytes(@NonNull PersistableBundle bundle) throws IOException {
+        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        bundle.writeToStream(outputStream);
+        return outputStream.toByteArray();
+    }
+
+    /**
+     * Converts from a disk-stable byte array format to a PersistableBundle
+     *
+     * @param bytes the disk-stable byte array
+     * @return the PersistableBundle parsed from this byte array.
+     */
+    public static PersistableBundle fromDiskStableBytes(@NonNull byte[] bytes) throws IOException {
+        final ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes);
+        return PersistableBundle.readFromStream(inputStream);
+    }
+
     /**
      * Ensures safe reading and writing of {@link PersistableBundle}s to and from disk.
      *

tests/vcn/java/com/android/server/vcn/util/PersistableBundleUtilsTest.java

@@ -267,6 +267,15 @@ public class PersistableBundleUtilsTest {
         assertTrue(PersistableBundleUtils.isEqual(testBundle, minimized));
     }
 
+    @Test
+    public void testToFromDiskStableBytes() throws Exception {
+        final PersistableBundle testBundle = getTestBundle();
+        final PersistableBundle result =
+                PersistableBundleUtils.fromDiskStableBytes(
+                        PersistableBundleUtils.toDiskStableBytes(testBundle));
+        assertTrue(PersistableBundleUtils.isEqual(testBundle, result));
+    }
+
     @Test
     public void testEquality_identical() throws Exception {
         final PersistableBundle left = getTestBundle();