First part of fix for issue #569

When moving to take into account arrayOffset, it should have been taken into account also in setReadPosition and other places. Fix it now...

src/main/java/org/jboss/netty/handler/codec/http/multipart/HttpPostBodyUtil.java

@@ -134,6 +134,8 @@ final class HttpPostBodyUtil {
         int readerIndex;
 
         int pos;
+        
+        int origPos;
 
         int limit;
 
@@ -148,7 +150,8 @@ final class HttpPostBodyUtil {
             }
             this.buffer = buffer;
             bytes = buffer.array();
-            pos = readerIndex = buffer.arrayOffset() + buffer.readerIndex();
+            readerIndex = buffer.readerIndex();
+            origPos = pos = buffer.arrayOffset() + readerIndex;
             limit = buffer.arrayOffset() + buffer.writerIndex();
         }
 
@@ -159,10 +162,19 @@ final class HttpPostBodyUtil {
         */
         void setReadPosition(int minus) {
             pos -= minus;
-            readerIndex = pos;
+            readerIndex = getReadPosition(pos);
             buffer.readerIndex(readerIndex);
         }
 
+        /**
+        *
+        * @param index raw index of the array (pos in general)
+        * @return the value equivalent of raw index to be used in readerIndex(value)
+        */
+        int getReadPosition(int index) {
+            return index - origPos + readerIndex;
+        }
+
         void clear() {
             buffer = null;
             bytes = null;