mojo: Fixing array serialization for java bindings.

The num_bytes header for an array must contain the real size of the
array, not the 8 bytes aligned one.

R=ppi@chromium.org

Review URL: https://codereview.chromium.org/519673002

Cr-Commit-Position: refs/heads/master@{#292656}

mojo/public/java/bindings/src/org/chromium/mojo/bindings/BindingsHelper.java

@@ -58,6 +58,13 @@ public class BindingsHelper {
         return (arrayNullability & ELEMENT_NULLABLE) > 0;
     }
 
+    /**
+     * Align |size| on {@link BindingsHelper#ALIGNMENT}.
+     */
+    public static long align(long size) {
+        return (size + ALIGNMENT - 1) & ~(ALIGNMENT - 1);
+    }
+
     /**
      * Compute the size in bytes of the given string encoded as utf8.
      */

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Decoder.java

@@ -66,6 +66,9 @@ public class Decoder {
         }
 
         public void claimMemory(long start, long end) {
+            if (start % BindingsHelper.ALIGNMENT != 0) {
+                throw new DeserializationException("Incorrect starting alignment: " + start + ".");
+            }
             if (start < mMinNextMemory) {
                 throw new DeserializationException("Trying to access memory out of order.");
             }
@@ -75,10 +78,7 @@ public class Decoder {
             if (end > mMaxMemory) {
                 throw new DeserializationException("Trying to access out of range memory.");
             }
-            if (start % BindingsHelper.ALIGNMENT != 0 || end % BindingsHelper.ALIGNMENT != 0) {
-                throw new DeserializationException("Incorrect alignment.");
-            }
-            mMinNextMemory = end;
+            mMinNextMemory = BindingsHelper.align(end);
         }
     }
 
@@ -111,17 +111,17 @@ public class Decoder {
         mMessage.buffer.order(ByteOrder.nativeOrder());
         mBaseOffset = baseOffset;
         mValidator = validator;
-        // Claim the memory for the header.
-        mValidator.claimMemory(mBaseOffset, mBaseOffset + DataHeader.HEADER_SIZE);
     }
 
     /**
      * Deserializes a {@link DataHeader} at the given offset.
      */
     public DataHeader readDataHeader() {
+        // Claim the memory for the header.
+        mValidator.claimMemory(mBaseOffset, mBaseOffset + DataHeader.HEADER_SIZE);
         int size = readInt(DataHeader.SIZE_OFFSET);
         int numFields = readInt(DataHeader.NUM_FIELDS_OFFSET);
-        // The memory for the header has already been claimed.
+        // Claim the remaining memory.
         mValidator.claimMemory(mBaseOffset + DataHeader.HEADER_SIZE, mBaseOffset + size);
         DataHeader res = new DataHeader(size, numFields);
         return res;

mojo/public/java/bindings/src/org/chromium/mojo/bindings/Encoder.java

@@ -148,7 +148,7 @@ public class Encoder {
      * (resizing the buffer if required).
      */
     public void encode(DataHeader s) {
-        mEncoderState.claimMemory(s.size);
+        mEncoderState.claimMemory(BindingsHelper.align(s.size));
         encode(s.size, DataHeader.SIZE_OFFSET);
         encode(s.numFields, DataHeader.NUM_FIELDS_OFFSET);
     }
@@ -438,7 +438,7 @@ public class Encoder {
     private Encoder encoderForArrayByTotalSize(int byteSize, int length, int offset) {
         encodePointerToNextUnclaimedData(offset);
         return getEncoderAtDataOffset(
-                new DataHeader(DataHeader.HEADER_SIZE + BindingsHelper.align(byteSize), length));
+                new DataHeader(DataHeader.HEADER_SIZE + byteSize, length));
     }
 
     private void encodeByteArray(byte[] bytes, int length, int offset) {