From 3f5ffa615a64a221d8d310beda6bad4fe1ac1e21 Mon Sep 17 00:00:00 2001
From: Jeongik Cha <jeongik@google.com>
Date: Tue, 24 Nov 2020 22:44:42 +0900
Subject: [PATCH] ParcelableHolder shouldn't write anything for empty case

If neither Parcel nor Parcelable exists, ParcelableHolder'd better
write nothing like NDK and C++ backend.

In the case of empty ParcelableHolder
As-is(Java):
 4 -> Size
 -1 -> Existence(empty string)

To-be(NDK, C++ now):
 0 -> Size

Test: atest CtsNdkBinderTestCases
Bug: 173682663
Change-Id: I816108fdc59170ea7408f0633295ba978f1ef9d5
---
 core/java/android/os/ParcelableHolder.java | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/core/java/android/os/ParcelableHolder.java b/core/java/android/os/ParcelableHolder.java
index 95c07b6b2451b..fb9fa109bfa30 100644
--- a/core/java/android/os/ParcelableHolder.java
+++ b/core/java/android/os/ParcelableHolder.java
@@ -170,16 +170,21 @@ public final class ParcelableHolder implements Parcelable {
 
         mParcelable = null;
 
+        int dataSize = parcel.readInt();
+        if (dataSize < 0) {
+            throw new IllegalArgumentException("dataSize from parcel is negative");
+        } else if (dataSize == 0) {
+            if (mParcel != null) {
+                mParcel.recycle();
+                mParcel = null;
+            }
+            return;
+        }
         if (mParcel == null) {
             mParcel = Parcel.obtain();
         }
         mParcel.setDataPosition(0);
         mParcel.setDataSize(0);
-
-        int dataSize = parcel.readInt();
-        if (dataSize < 0) {
-            throw new IllegalArgumentException("dataSize from parcel is negative");
-        }
         int dataStartPos = parcel.dataPosition();
 
         mParcel.appendFrom(parcel, dataStartPos, dataSize);
@@ -196,6 +201,11 @@ public final class ParcelableHolder implements Parcelable {
             return;
         }
 
+        if (mParcelable == null) {
+            parcel.writeInt(0);
+            return;
+        }
+
         int sizePos = parcel.dataPosition();
         parcel.writeInt(0);
         int dataStartPos = parcel.dataPosition();