Fix the ArrayIndexOutOfBoundsException of ByteBucketArray

The framework starts to use a preserved staging-public-group for new
attributes on the new platform. The group has a bigger bucket id whose
leading bit is 1, which causes a Java signed/unsigned number problem in
multiple byte-integer conversions.

The bucket id has four bits which has a maximum number 15(0xf). However,
when the leading bit is 1, Java will auto-cast the byte to a negative
integer and cause an ArrayIndexOutOfBoundsException.

To solve this, converting the id to an unsigned integer can help Java
treat it as a positive number.

Fixes: 197494608
Bug: 196297712
Test: robotest
Change-Id: Ie5027621df2bf134ca5c5cee60c423db47f47ca7

1 files changed, 3 insertions, 3 deletions

diff --git a/resources/src/main/java/org/robolectric/res/android/ByteBucketArray.java b/resources/src/main/java/org/robolectric/res/android/ByteBucketArray.java
index 209fb1ee8..0636e1921 100644
--- a/resources/src/main/java/org/robolectric/res/android/ByteBucketArray.java
+++ b/resources/src/main/java/org/robolectric/res/android/ByteBucketArray.java
@@ -24,7 +24,7 @@ public abstract class ByteBucketArray<T> {
     }
 
 //    byte bucketIndex = static_cast<byte>(index) >> 4;
-    byte bucketIndex = (byte) (index >> 4);
+    byte bucketIndex = (byte) (Byte.toUnsignedInt((byte) index) >> 4);
     T[] bucket = (T[]) mBuckets[bucketIndex];
     if (bucket == null) {
       return mDefault;
@@ -38,7 +38,7 @@ public abstract class ByteBucketArray<T> {
 //        (uint32_t) index, (uint32_t) size());
 
 //    uint8_t bucketIndex = static_cast<uint8_t>(index) >> 4;
-    byte bucketIndex = (byte) (((byte) index) >> 4);
+    byte bucketIndex = (byte) (Byte.toUnsignedInt((byte) index) >> 4);
     Object[] bucket = mBuckets[bucketIndex];
     if (bucket == null) {
       bucket = mBuckets[bucketIndex] = new Object[BUCKET_SIZE];
@@ -60,7 +60,7 @@ public abstract class ByteBucketArray<T> {
     }
 
 //    editItemAt(index) = value;
-    byte bucketIndex = (byte) (((byte) index) >> 4);
+    byte bucketIndex = (byte) (Byte.toUnsignedInt((byte) index) >> 4);
     Object[] bucket = mBuckets[bucketIndex];
     if (bucket == null) {
       bucket = mBuckets[bucketIndex] = new Object[BUCKET_SIZE];